Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: BulletVI on August 16, 2010, 10:30:37 AM
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Now for a while in the game i have always thought that the merlin engine hasn't reached its potential. And i believed that it was due to its RPM out put in the game.
I mean i never thought that at full wep the engine only achieved 2750 rpm's so i have for a couple of months now been trying to see if i am wrong or correct.
Now im sorry but allot of my info i have found is from wikipeadia and we know that their info is either vague or not updated fast enough. But the spec's they give make for some interesting reading on the subject.
Here's a couple of links to what i have found :)
http://en.wikipedia.org/wiki/Rolls-Royce_Merlin
http://spitfiresite.com/2010/04/the-development-of-rolls-royce-merlin-engine.html
Now as you can see it says for the very first Merlin engine it produced 1030bhp at 3000 rpm at a given height.
Now in the game i dont see the merlin in the Spit or mustang ,Lancaster or the Mossi able to go to 3000rpm even on full wep :)
Now i ask if anyone can help with further research you are welcome to help it shall be greatly appreciated.
Now i dont expect that if we are proved right that it has to be sorted right away. But if we are right can we have it sorted by the next update :)
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Can't go at higher RPM because of the propeller is so large that its tips are not designed to have a tangential velocity greater than the speed of sound or some other aerodynamic constraint. The smaller the prop, the faster is can rotate. Why do you think very small turbine engines spin at 80,000rpm and large jumbo airliners have them spin at around 12500RPM (3,000RPM for main fan)? And remember, the propeller RPM is not the same as engine RPM because there is a gear box between the prop and engine. Although modern propellers can be designed to rotate faster and quieter, they still have a limit not dependent on the engine max RPM.
But this is just one of many other reasons I'm sure others will pull out.
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That is true Lepape2 but if the merlin engine is capable of 3000 rpm and in game we only get say around 2750 rpm with full wep on surely we all can do more research on this as what i have posted probably wont change or spur hitech in to action. If more and in depth research is done then maybe just maybe we can get it right.
As hitech has said he strive's to make Ace's the most realistic Combat Sim to date. And we as Paying customer's should help him to achieve that no matter what :)
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As hitech has said he strive's to make Ace's the most realistic Combat Sim to date. And we as Paying customer's should help him to achieve that no matter what :)
How many times has this sentence been refuted countless times because some guy thinks the makers have a simulator that does not reflex reality while they have been on it for 2 decades or more? At this point in the game development, you have to trust its features because so much has already been discussed that its unlikely that you can find something wrong by just looking at wikipedia charts...
Wikipedia is only worthy for knowledge with mathematical data and not statistical or historical data, although the numbers are right most of the time.
Make sure you are comparing the correct aircraft type/model as well with the game.
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Bullet:
Very interesting. According to Jane's....the Spit IX's engine was more HP but the Spit VIII and Spit XVI had the same engines but were manufactured by different companies. From this chart it would appear to me that in-game Seafire is grossly underpowered vs. the HP it claims to have had. Understanding the power to weight ratio because it was a carrier launched and landed a/c it's obviously going to be heavier.
Main article: List of Rolls-Royce Merlin variants
This is a summary list of representative Merlin variants. Engines of the same power output were typically assigned different model numbers based on supercharger or propeller gear ratios, differences in cooling system or carburettors, engine block construction, or arrangement of engine controls.[67] All but the Merlin 131 and 134 engines were "right-hand tractor", i.e. the propeller rotated to the right when viewed from the rear.
Data from Bridgman (Jane's)[68] unless otherwise noted:
Merlin II or III
1,030 hp (775 kW) at 3,000 rpm at 5,500 ft (1,680 m) using + 6 psi boost (41 kPa gauge; or an absolute pressure of 144 kPa or 1.41 atm); Merlin III fitted with "universal" propeller shaft able to mount either de Havilland or Rotol propellers,[69]
1,310 hp (977 kW) at 3,000 rpm at 9,000 ft (2,700 m) with 100 octane fuel and +12 psi boost (83 kPa gauge; or an absolute pressure of 184 kPa or 1.82 atm) (Merlin III);[43] both used in the Boulton Paul Defiant, Hurricane Mk.I, Spitfire Mk.I fighters, and Fairey Battle light bomber.[70]
Merlin X
1,130 hp (840 kW) at 3,000 rpm at 5,250 ft (1,525 m); used in Halifax Mk.I, Wellington Mk.II, and Whitley Mk.V bombers.
Preserved Merlin XX at the Royal Air Force MuseumMerlin XII
1,150 hp (860 kW); fitted with Coffman engine starter; first version to use 70/30% water/glycol coolant rather than 100% glycol. Fitted to Spitfire Mk. II.[69]
Merlin XX
1,480 hp (1,105 kW) at 3,000 rpm at 6,000 ft (1,830 m); used in Beaufighter Mk.II and Hurricane Mk.II fighters, Halifax Mk.II and Lancaster Mk.I bombers.
Merlin 32
1,645 hp (1,230 kW) at 3,000 rpm at 2,500 ft (760 m); used mainly in Fleet Air Arm aircraft; used in Barracuda Mk.II torpedo bomber and Seafire IIc. Also Hawker Hurricane Mk V and Spitfire P.R Mk XIII.[69] and
Merlin 45
1,515 hp (1,130 kW) at 3,000 rpm at 11,000 ft (3,353 m); used in Spitfire Mk.V, PR.Mk.IV and PR.Mk.VII, Seafire Ib and IIc.
Merlin 47
1,415 hp (1,055 kW) at 3,000 rpm at 14,000 ft (4,270 m); high-altitude version used in Spitfire H.F Mk VI. Adapted with a Marshall compressor (often called a "blower") to pressurise the cockpit.
Merlin 50.M
1,585 hp (1,182 kW) at 3,000 rpm at 3,800 ft (1,160 m); low-altitude version with supercharger impeller "cropped" to 9.5 inches (240 mm) in diameter. Permitted boost was +18 psi (125 kPa gauge; or an absolute pressure of 225 kPa or 2.2 atm) instead of +16 psi (110 kPa gauge; or an absolute pressure of 210 kPa or 2.08 atm) on a normal Merlin 50 engine. A "negative-g" carburettor was fitted.[71][72]
Merlin 61
1,565 hp (1,170 kW) at 3,000 rpm at 12,250 ft (3,740 m)
1,390 hp (1,035 kW) at 3,000 rpm at 23,500 ft (7,170 m); fitted with a new two-speed two-stage supercharger providing increased power at medium to high altitudes; used in Spitfire F. Mk IX, and P.R.Mk XI.[73] First British production variant to incorporate two-piece cylinder blocks designed by Rolls-Royce for Packard Merlin.[74]
Merlin 66
1,720 hp (1,283 kW) at 5,750 ft (1,752 m) using +18 psi boost (124 kPa gauge; or an absolute pressure of 225 kPa or 1.2 atm); low-altitude version of Merlin 61. Fitted with a Bendix-Stromberg anti-g carburettor;[75] used in Spitfire L.F Mk VIII and L.F Mk IX.[71]
Merlin 76/77
1,233 hp (920 kW); used in the Westland Welkin high-altitude fighter and some later Spitfire and Mosquito variants. Fitted with a two-speed, two-stage supercharger and a Bendix-Stromberg carburettor. The odd-numbered mark drove a blower for pressurising the cockpit.
Merlin 130/131
2,060 hp (1,536 kW); redesigned "slimline" versions for the de Havilland Hornet. Engine modified to decrease frontal area to a minimum and was the first Merlin series to use down-draught induction systems. Coolant pump moved from the bottom of the engine to the starboard side. Two-speed, two-stage supercharger and S.U. injection carburettor. Maximum boost was 25 psi (170 kPa gauge; or an absolute pressure of 270 kPa or 2.7 atm). The Merlin 131 had an additional idler gear in the reduction gear casing allowing "reverse" (left-hand tractor) rotation. The Merlin 130 was fitted in the starboard nacelle, Merlin 131 in the port nacelle on production Hornets.[76]
Merlin 133/134
2,030 hp (1,514 kW); derated variants of 130/131 used in Sea Hornet F. Mk. 20, N.F. Mk. 21 and P.R. Mk. 22. Maximum boost was lowered to +18 psi gauge (230 kPa or 2.2 atm absolute).
Merlin 266
The prefix "2" indicates engines built by Packard, otherwise as Merlin 66, optimised for low-altitude operation. Fitted to the Spitfire Mk. XVI.[71]
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How many times has this sentence been refuted countless times because some guy thinks the makers have a simulator that does not reflex reality while they have been on it for 2 decades or more? At this point in the game development, you have to trust its features because so much has already been discussed that its unlikely that you can find something wrong by just looking at wikipedia charts...
Wikipedia is only worthy for knowledge with mathematical data and not statistical or historical data, although the numbers are right most of the time.
Make sure you are comparing the correct aircraft type/model as well with the game.
Agreed. The performance data may appear in Wikipedia articles but the source data can be verified easily from trusted sources...such as Jane's. I trust Jane's because Lloyd's of London trusts Jane's and Lloyd's is the biggest BOOKIE in the history of modern society. That being said, I am unsure of what you mean by statistical and historical data...isn't the sim modeled from mathematical data? I would think statistical and historical data are irrelevent for sim purposes...the a/c's performance envelope is developed based on its mathematical performance specs (knowing full well that those are numbers that are technically historical right?) and then the pilots fly them as best they can.
Changeup
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As in my first post i said that this is early finding's i am constantly searching for more data from various source's hell even if i have to call in a few favours to get the info i shall do it. As i also said at present the in game programing for the merlin engine wont be changed on this alone but some data doesnt addup. like
The Merling puts out 3000 rpm maximum and in game with full wep on we dont reach that. That is my point. Now i hear you say whats a few hundred rpm's. But in combat that make's a difference between out diving a 109 to catching it in a dive.
Now if proven that say the merlin puts out 2750 rpm at full power and with wep it then puts out 3000 rpm then hey good. Or even if hitech come's in and says oops sorry minor default in the animation of the rpm gauge it should show 3000rpm then cool topic over with. :)
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Oh for Pete's sake.
Even the wikipedia source link - as cruddy a source as wikipedia is - mentions the aircrew reduction gearing, although it doesn't give any details as to what the gearing would have been in the various implementations.
Crankcase
Two aluminium-alloy castings joined together on the horizontal centreline. The upper portion bears the wheelcase, supercharger and accessories; and carries the cylinder blocks, crankshaft main bearings (split mild-steel shells lined with lead bronze alloy), and part of the housing for the airscrew reduction gear. The lower half forms an oil sump and carries the oil pumps and filters.
Why do you think they refer to it as a reduction gear?
The RPM's that you are monitoring in the game are for the propeller - which depending upon specific aircraft design may or may not vary from the engine RPM's considerably, depending upon at what RPM's the engine used developed peak power and which design trade-offs were deemed most important with respect to the propeller.
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WEP increases power not RPM. We have 3000 RPM in AH.
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(http://i234.photobucket.com/albums/ee181/goldeagle2111/popcorn.gif)
(http://smileys.on-my-web.com/repository/Drinks/drinking-50.gif)
Great seats...
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You sure according to sources the rpm gauge shows engine rpm from the flywheel of the engine not propelar rpm as engine rpm is easyer to measure. and accurate. Wep does increase power but upon increase of power you receive an increase of rpm's :)
Please if you only just want to needle the topic please stay out of it thankyou :)
Please read
http://www.k5083.mistral.co.uk/TECHDATA.HTM
http://www.luftfahrtmuseum.com/htmi/itf/rrmr724.htm
( Heck even if the engine can only last for a certain time at full rpm then fine let us do the damage to it :) )
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This is a doc with sources and original 1938 - 1945 documents. I don't know that it matters but its damn cool. BTW, I have flown the Spit I and I can't remember it performing like this in-game that is for sure.
http://www.spitfireperformance.com/spit1vrs109e.html
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This is a doc with sources and original 1938 - 1945 documents. I don't know that it matters but its damn cool. BTW, I have flown the Spit I and I can't remember it performing like this in-game that is for sure.
http://www.spitfireperformance.com/spit1vrs109e.html
That was a nice and interesting read changeup :salute :) :aok
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This might help (Have Java turned off so don't know if there actually IS a calculator, but the text does seem accurate when put into forumlas
Is a prop speed/length to RPM calculator.
http://www.pponk.com/HTML%20PAGES/propcalc.html
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This might help (Have Java turned off so don't know if there actually IS a calculator, but the text does seem accurate when put into forumlas
Is a prop speed/length to RPM calculator.
http://www.pponk.com/HTML%20PAGES/propcalc.html
there is a calculator there thanks i shall give it a go :)
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The power outputs of AHs merlins are correct (you can tell from the climbrate and level speed charts.) Apart from the Lanc's merlins which are denied their WEP setting for some reason (while other buffs fly around with permawep ...)
The rpm gauge shows engine rpm, not prop rpm.
The rpm gauge does indeed need a little tweak, mine shows 2900-2950 on WEP. just moving the needle position wont however make any difference to the performance.
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The power outputs of AHs merlins are correct (you can tell from the climbrate and level speed charts.) Apart from the Lanc's merlins which are denied their WEP setting for some reason (while other buffs fly around with permawep ...)
The rpm gauge shows engine rpm, not prop rpm.
The rpm gauge does indeed need a little tweak, mine shows 2900-2950 on WEP. just moving the needle position wont however make any difference to the performance.
That is another fact i was willing to accept that the needle animation may be needing re calibrated to show 3000 rpm as if it is that then it will stop any other player who may be new or not seen this or previous posts reposting about it. That as i say i also considered what this was what was wrong :)
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Post which aircraft model has an incorrect gauge reading in the bug forum and it will be adjusted.
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Post which aircraft model has an incorrect gauge reading in the bug forum and it will be adjusted.
At the moment it is all variants of the Spitfire. ( And maybe the P51 and Lancaster )
But in saying that it may be incorrect reading or it may be that the engine model need's tweaking as well only hitech and co can say what it is.
All i ask is for them to say ok we shall look into it. And i don't mind having to wait a few weeks for them to look at it and sort it as they are bound to be busy :)
But as well by reading a link that was posted by Changeup it sounds like you got 3000 rpm from full throttle with extra from the wep when used :) ????
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Lets see...
Huge glaring rookie error on HTC's part that has been missed by 1,000's of players for the past 10 years.
or...
Bullet read something, didn't understand it or became confused over some basic principal, and then made yet another post on a topic he doesn't even have a basic grasp of and trying to tell HTC they are wrong.
Think i'm gonna go w/ the latter.
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Lets see...
Huge glaring rookie error on HTC's part that has been missed by 1,000's of players for the past 10 years.
or...
Bullet read something, didn't understand it or became confused over some basic principal, and then made yet another post on a topic he doesn't even have a basic grasp of and trying to tell HTC they are wrong.
Think i'm gonna go w/ the latter.
:rofl :lol Ditto...
(http://i234.photobucket.com/albums/ee181/goldeagle2111/popcorn.gif)
(http://smileys.on-my-web.com/repository/Drinks/drinking-50.gif)
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Lets see...
Huge glaring rookie error on HTC's part that has been missed by 1,000's of players for the past 10 years.
or...
Bullet read something, didn't understand it or became confused over some basic principal, and then made yet another post on a topic he doesn't even have a basic grasp of and trying to tell HTC they are wrong.
Think i'm gonna go w/ the latter.
It could just be a simple animation fault in the rpm gauge and no-one has noticed or even thought about it till now :)
OH and WMLute
I shall be the first to admit it but in the real world i know and understand engines and flight dynamic's. But to take it and put it in-to virtual Sim's like ace's with coading or however it is done i don't have a clue. Now if i have just picked up a simple animation fault that no-one has cough-ten on to then it will be a simple fix that hitech and co can do in moment's ( i think ). But if through the past 10 year's of updates and the programming of these new update's do you not think that it may be simple or even possible for the team to have a couple of number's in the coading the wrong way round ( its bound to happen :) ) or as i said it could be just the rpm gauge needing a fix to show 3000 rpm's. this i believe is the most likley fault is the animation on the rpm gauge. But we wont know till the team at hitech takes a look at it wont we so please keep quiet if you dont have anything or dont want to be apart of this topic.
Thankyou BulletVI
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It could just be a simple animation fault in the rpm gauge and no-one has noticed or even thought about it till now :)
OH and WMLute
I shall be the first to admit it but in the real world i know and understand engines and flight dynamic's. But to take it and put it in-to virtual Sim's like ace's with coading or however it is done i don't have a clue. Now if i have just picked up a simple animation fault that no-one has cough-ten on to then it will be a simple fix that hitech and co can do in moment's ( i think ). But if through the past 10 year's of updates and the programming of these new update's do you not think that it may be simple or even possible for the team to have a couple of number's in the coading the wrong way round ( its bound to happen :) ) or as i said it could be just the rpm gauge needing a fix to show 3000 rpm's. this i believe is the most likley fault is the animation on the rpm gauge. But we wont know till the team at hitech takes a look at it wont we so please keep quiet if you dont have anything or dont want to be apart of this topic.
Thankyou BulletVI
I get just a sliver from 3000 rpm. Close enough for me. Maybe its just you and your un-calibrated slider?
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I get just a sliver from 3000 rpm. Close enough for me. Maybe its just you and your un-calibrated slider?
I have looked in to that since the point of the gauge animation was wrong and i recalibrated my stick and throttle but my rpm gauge still only goes to 2750 rpm at full throttle :)
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I have looked in to that since the point of the gauge animation was wrong and i recalibrated my stick and throttle but my rpm gauge still only goes to 2750 rpm at full throttle :)
Are you using wep?
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Bullet you need to cite a specific aircraft and document your data. You can't assume that all aircraft with Merlins have the same max RPM.
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It's not that the RPM is miscalibrated, it's that the center around which it pivots is just ever so slightly off (too high) so that when it's at 3000 RPM the needle is "too high" and thus really points at something less than 3000 RPM.
You can tell this is the case because it says right there on the E6B "3000 RPM" for WEP.
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That is true Lepape2 but if the merlin engine is capable of 3000 rpm and in game we only get say around 2750 rpm with full wep on surely we all can do more research on this as what i have posted probably wont change or spur hitech in to action. If more and in depth research is done then maybe just maybe we can get it right.
As hitech has said he strive's to make Ace's the most realistic Combat Sim to date. And we as Paying customer's should help him to achieve that no matter what :)
Awesome on the Engine being rated at 3000rpm, but Prop's are rated as well.
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Bullet when you takeoff at sea level in a P51 and you use full throttle does the gauge NOT read 3000?
EDIT: If you cant there is something wrong with your setup.
Try this.
Take off at full power and then when its safe to do so lower the RPM to 2700 and jockey the trottle to maintain 46" MP. As you climb through about 9600 feet you will notice you have to move the throttle up to hold 46" MP and the RPM remains at 2700. At this point if you move the RPM back to 3000 you will see 61" MP again. During the climb there will come a point (if memory serves its 14300 feet) where you can no longer hold 46" MP. MP will continue to drop until 16300 feet where the efficiency of the supercharger kicks in and MP climbs again until at 17300 feet you can once again hold 46" MP steady (or push it to 61" by increasing RPM to 3000). The maximum cruise alt is 24600 feet where you can hold 2500 RPM and 43" MP above that MP will drop and above 25000 feet MP can no longer hold at 61" even at 3000 RPM.
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Bullet when you takeoff at sea level in a P51 and you use full throttle does the gauge NOT read 3000?
EDIT: If you cant there is something wrong with your setup.
Try this.
Take off at full power and then when its safe to do so lower the RPM to 2700 and jockey the trottle to maintain 46" MP. As you climb through about 9600 feet you will notice you have to move the throttle up to hold 46" MP and the RPM remains at 2700. At this point if you move the RPM back to 3000 you will see 61" MP again. During the climb there will come a point (if memory serves its 14300 feet) where you can no longer hold 46" MP. MP will continue to drop until 16300 feet where the efficiency of the supercharger kicks in and MP climbs again until at 17300 feet you can once again hold 46" MP steady (or push it to 61" by increasing RPM to 3000). The maximum cruise alt is 24600 feet where you can hold 2500 RPM and 43" MP above that MP will drop and above 25000 feet MP can no longer hold at 61" even at 3000 RPM.
I know of the different throttle settings and the fact at different altitudes i need to either reduce or increase throttle to maintain a certain rpm.
But there is now a clincher that of what i read from a statement from a Spitfire pilot.
It has been copied and pasted in the next post :)
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http://www.spitfireperformance.com/spit1vrs109e.html
Ok from the above link read what P/O David Crook has said in his first paragraph.its about a 1/4 of the way down the page :)
Now to me that sounds like he throttled up to 3000 rpm then initiated his push past to gain wep. ????
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not hunting around to find that, why dont you just quote it?
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Bullet you should have realized by now that the RPM control is pitch control of the propeller. Lower RPM is broader pitch and higher RPM is thinner pitch or in other words when you decrease RPM to minimum you are in effect feathering the prop. When the engine can no longer produce a certain minimum of power it cannot maintain the propeller at higher RPMs. This is why at certain extreme altitudes the engine must be left at FT and only the engine RPM controls managed for maximum endurance or even left at highest RPM attainable for that altitude just to remain flying.
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not hunting around to find that, why dont you just quote it?
i couldnt copy and paste it but here you are :)
A quote from P/O David Cook
" It was obviously a matter of moments only before we where in the thick of it. I turned my trigger onto Fire, Increased the engine revs to, 3000 rpm by slipping the constant speed control fully forward. And pulled the plug, i.e. Pushed the small handle on the throttle quadrant that cuts out the automatic boost thus allowing one to use emergency power. "
Now to me that says he increased rpm's to 3000 then used wep to gain more power. Not what we have in game throttle up to 2750 rpms say and use wep and now have 3000 rpms ???? i dont know how you shall interpret this quote but you are free to do so in any way :)
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The constant speed control is a propeller control not an engine control.
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The constant speed control is a propeller control not an engine control.
yes he had his throttle at max and his constant speed control at full as well to reach 3000rpm then wep to give more power thus more power more engine revs ok. so with wep on what would his revs be ? well that depends on hw much extra boost was supplied to the engine. If its plus 2 boost the the engine is now doing say 3250 rpm's ?????
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No 3000 RPM. If you take any Merlin airplane up in AH (as far as I know) the RPM control is designed to deliver 3000 RPM whenever the engine is in WEP. Of course I dont know anything about Spitfires but I would bet that IRL if you moved to emergency boost without also setting the RPM correctly that it would not be as effective in combat. I dont believe that RPM would go above 3000 without wrecking the propeller.
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yes he dialled in 3000rpm and broke the wire on the boost. just like in AH, except we have one button which does both.
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i couldnt copy and paste it but here you are :)
A quote from P/O David Cook
" It was obviously a matter of moments only before we where in the thick of it. I turned my trigger onto Fire, Increased the engine revs to, 3000 rpm by slipping the constant speed control fully forward. And pulled the plug, i.e. Pushed the small handle on the throttle quadrant that cuts out the automatic boost thus allowing one to use emergency power. "
Now to me that says he increased rpm's to 3000 then used wep to gain more power. Not what we have in game throttle up to 2750 rpms say and use wep and now have 3000 rpms ???? i dont know how you shall interpret this quote but you are free to do so in any way :)
No bullet, why is this so hard to understand? It clearly states that he got the engine to run at 3000 rpm by increasing the prop rpm AND initiating boost. Stop twirling words in a manner to support your pointless argument.
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Well there as we all know umpteen ways of looking at it and interpreting this story but to me it sounds like you can take the merlin engine up to 3000 rpms and use your wep for 5 minutes as any longer will cause engine damage. Oh and i was reading abit about prop rpms as well if the engine is at 3000rpm depending on the reduction gearbox setup the prop can be doing 9000rpms :) that i read in my collection of Air-plane the world encyclopaedia of aircraft from 1914 - 1999. :)
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Amazing how the airframes engineer genius couldn't copy and paste the text...
P/O David Crook, with No. 609 Squadron at Middle Wallop, published an interesting account in his book of his most successful day of the Battle of Britain, 30 September 1940:
It was now obviously a matter of moments only before we were in the thick of it. I turned my trigger on to 'Fire', increased the engine revs. to 3000 r.p.m. by slipping the constant speed control fully forward, and 'pulled the plug', i.e. pushed the small handle on the throttle quadrant that cuts out the automatic boost control thus allowing one to use emergency power.
A few seconds later, about six Me. 109s flew across right in front of us. I don't think they saw us till too late as we were coming out of the sun. Michael was leading Blue Section and I was leading Green, and immediately we swung our sections round and turned on to the tails of the enemy. They saw us - too late - and tried to escape by diving.
We all went down after them in one glorious rush and I saw Michael, who was about a hundred yards ahead of me, open fire at the last Messerschmidt in the enemy line. A few seconds later, this machine more or less fell to pieces in mid-air - some very nice shooting on Michael's part. I distinctly remember him saying on the R.T., 'That's got you, you bastard,' though he never recollects it!
The victim that I had selected for myself was about 500 yards ahead of me, and still diving hard at very high speed. God, what a dive that was! I came down on full throttle from 27,000 feet to 1,000 feet in a matter of seconds, and the speed rose with incredible swiftness - 400 m.p.h., 500, 550, 600 m.p.h. I never reached this speed before and probably never shall again. I have a dim recollection of the sea coming up towards me at an incredible rate and also feeling an awful pain in my ears, though I was not really conscious of this in the heat of the moment. I pulled out of the dive as gently as I could, but the strain was terrific and there was a sort of black mist in front of my eyes, though I did not quite 'black out'.
The Messerschmidt was now just ahead of me. I came up behind him and gave him a terrific burst of fire at very close range. The effect of a Spitfire's eight guns has to be seen to be believed. Hundreds of bullets poured into him and he rocked violently, then turned over on his back, burst into flames and dived straight down into the sea a few miles off Swanage. The pilot made no attempt to get out and was obviously dead. I watched him hit the water in a great cloud of white foam, and then turned round to see what else was going on.
A few of our Spitfires were chasing Messerschmidts all over the place and obviously a very nice little massacre was in progress, as a few seconds later I saw another Hun go into the sea. I then saw another Me. 109 going back to France as hard as he could and I chased him, caught him fairly easily, and put a good burst into him. He swerved slightly, his cockpit covering broke off the machine and flew just past my head and he then dived steeply.
I waited to see him hit the water, but he was only shamming, as he flattened out again just above the sea, and continued full speed for home, though his machine was now smoking and obviously badly hit.
For the first time in this war, I felt a certain pity for this German pilot and reluctant to finish him off. From the moment I saw him, he had no chance of escape as my Spitfire was so much faster than his Messerschmidt, and the last few moments must have been absolute hell for him. I could almost feel his desperation as he made this last attempt to get away.
But if I let him go, he would come back to England another day and possibly shoot down some of our pilots. In the few seconds during which all this was happening, I did not consciously make these reflections; my blood was up anyway and I was very excited, but distinctly remember feeling rather reluctant.
However, I caught him up again and made no mistake this time. I fired all my remaining ammunition at very close range, and he crashed into the sea, going at a terrific speed, and disappeared immediately. I circled round the spot, but there was no trace of anything. 71
It's a real shame Bullet doesn't read with better comprehension...that entire page is about the Spit I with a constant speed propeller compared to the Bf-109Es in 1940.
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yup sorry google chrome is weird on copy and paste from copyrighted pages and sutch :) But hey if you are 2 Dumb to understand me then i am not the Dumb one you are. all i am saying if in game we get 3000rpm with the wep on then to me that sounds wrong from what i have read it sounds like we can get 3000 rpm before we use wep and wep is that lovely little extra boost we get for diving on our target or for the escape :)
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Bullet... end of story here... the RPM gauge in AH is prop RPM. You can prove it to yourself easily. Takeoff in your favorite airplane (probably the Spit XVI) and climb to 10k or so. Leave the airplane in auto-climb (in case you want to get back to auto-climb its ALT-X) and once you get to the target altitude shut the engine off. After the nose settles you will be back at your climb speed but you will be nose down gliding. Now pull the RPM back with either your RPM axis ir with the minus key "-" from the keypad. You will notice that your nose will raise a little relative to the horizon. Now if RPM was related to the engine how does it effect trim attitude? Simple! Its prop RPM! It has nothing to do with the engines manifold pressure.
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um no - the cockpit gauge shows the engine speed in rpm, the AH "rpm control" controls the prop speed (via its pitch.)
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um no - the cockpit gauge shows the engine speed in rpm, the AH "rpm control" controls the prop speed (via its pitch.)
Check again.
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um no - the cockpit gauge shows the engine speed in rpm, the AH "rpm control" controls the prop speed (via its pitch.)
Correct.
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Correct.
Quote from: BulletVI on June 20, 2010, 01:39:02 PM
But HiTech i think there may be 1 factor that has been left out in the game. and that's drag.
You know i was right in a way about this quote Masherbrum :)
The game certainty aint a DRAG ( by that i mean boering :lol )
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Quote from: BulletVI on June 20, 2010, 01:39:02 PM
But HiTech i think there may be 1 factor that has been left out in the game. and that's drag.
You know i was right in a way about this quote Masherbrum :)
The game certainty aint a DRAG ( by that i mean boering :lol )
Shades accounts are fun to poke with a stick from time to time.
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I just tested it offline. The RPM gauge will still hold a reading with the engine off. Changing the RPM via prop control will drop the RPM reading on the gauge. That seems to indicate the RPM gauge is reading prop RPM and not engine RPM.
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I just tested it offline. The RPM gauge will still hold a reading with the engine off. Changing the RPM via prop control will drop the RPM reading on the gauge. That seems to indicate the RPM gauge is reading prop RPM and not engine RPM.
I have noticed that if your throttle slider is set to change RPM 1 that happens its like you cant stop the prop from spinning at say 2000 rpm but if tou set it to change THROTTLE 1 then when you idle the engine both the engine and prop idle. :)
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Check again.
Its an engine speed indicator...Whats so hard to understand about this concept? Change the pitch of the prop you change the load on the engine.
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I just tested it offline. The RPM gauge will still hold a reading with the engine off. Changing the RPM via prop control will drop the RPM reading on the gauge. That seems to indicate the RPM gauge is reading prop RPM and not engine RPM.
No, no it's indeed reading engine RPM. How this is related to the propeller is that blade pitch changes the amount of power required to turn the propeller which affects how fast the crankshaft of the engine actually spins. In a windmilling case the crankshaft continues to spin thanks to oncoming air creating a load on the propeller which spins it. The engine RPM will vary with variation of the amount of blade pitch because different relative angles of attack on the prop means different thrust and drag produced by the prop and thus the amount of load it actually takes to spin the prop.
In other words RPM setting on a constant speed prop is defining how fast the engine crankshaft can spin by varying the amount of power required to spin the propeller connected to it through adjustment of propeller blade pitch.
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Its an engine speed indicator...Whats so hard to understand about this concept? Change the pitch of the prop you change the load on the engine.
yes you do at that.
All though an earlier flight sim i used to play years back on the rpm gauge you had 2 needles one was white with red stripes and that was prop rpm the other a white needle and that was engine rpm. i dont know if the real Spits had that set up but hey i dont think the game was true facual based :)
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Get into a Spit XVI and look closely at the RPM gauge and you will see that it goes to 12000 RPM. The reason it doesnt go that high in AH is because Hitech decided it would not be fun to have to work the engine controls and that is proven every time anyone has a question like this (or mistaken idea). If you were at 15k IRL and dived upon a con at 6k without pulling your prop RPM back the propeller would overrun and be useless. So in the game it is limited to 3000 RPM (slightly less in the Spit XVI for some reason) depending on manufacturer I guess.
Someone said something about the speed of sound and the size of the Mustang prop but thats inaccurate also. The F4U and P47 props are of much larger diameter and dont have that problem either. None of these airplanes and none of their props ever got near the speed of sound. If they had gotten near the speed of sound then the props would have been destroyed long before the airframes (tip speed on the P-51 is something like 380 mph at 3000 RPM).
jamdive: why does it read RPM with the engine off? Its not reading engine RPMs.
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yes you do at that.
All though an earlier flight sim i used to play years back on the rpm gauge you had 2 needles one was white with red stripes and that was prop rpm the other a white needle and that was engine rpm. i dont know if the real Spits had that set up but hey i dont think the game was true facual based :)
Its an engine speed indicator.
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And yet another fact that stoped the prop tips going near the speed of sound was the reduction gear box between the prop and the engine and another control system that was controlled by the engine oil that adjusted the props angle if you over speed the prop in a dive but that system i believe was only invented in mid 1944 :)
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Its an engine speed indicator.
I know but that is what an earlier game i used to play had so it was easy to tell and such :)
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And yet another fact that stoped the prop tips going near the speed of sound was the reduction gear box between the prop and the engine and another control system that was controlled by the engine oil that adjusted the props angle if you over speed the prop in a dive but that system i believe was only invented in mid 1944 :)
Its a friggin governor.....You being some airframes/powerplant engineer should understand this basic concept.
P/S. stop arguing and go learn something.
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jamdive... while I agree it should be a tachometer it does not act like a tachometer when it still reads RPMS with the engine off. In the P-51 it was a tachometer but in AH it acts as though it is reading prop RPM. Thats just what the evidence shows.
Now if you can show me that an engine like a Merlin will still rotate once it is turned off and therefore give an indication on an RPM gauge then I might side with you but until then I must conclude the RPM gauge is measuring prop RPM.
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Chalenge, you skipped my post above. The RPM gauge is reading engine RPM. A windmilling propeller continues to spin the crankshaft of the engine.
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jamdive... while I agree it should be a tachometer it does not act like a tachometer when it still reads RPMS with the engine off. In the P-51 it was a tachometer but in AH it acts as though it is reading prop RPM. Thats just what the evidence shows.
Now if you can show me that an engine like a Merlin will still rotate once it is turned off and therefore give an indication on an RPM gauge then I might side with you but until then I must conclude the RPM gauge is measuring prop RPM.
What do you mean by "when the engine is turned off" ? If the prop is spinning so is the engine, and that gauge in cockpit comes off the engine camshaft. I still don't get the confusion.
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If you dive the Spit 14 you can get 4500 RPM.
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Its a friggin governor.....You being some airframes/powerplant engineer should understand this basic concept.
P/S. stop arguing and go learn something.
Ahem i was tought it to be called a reduction gearbox as to spin the prop at a 3-1 ratio from the engine rpm hence the engine idles at 1000 rpm the prop is doing 3000 rpm at the outer edge. :)
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Ahem i was tought it to be called a reduction gearbox as to spin the prop at a 3-1 ratio from the engine rpm hence the engine idles at 1000 rpm the prop is doing 3000 rpm at the outer edge. :)
What does that have to do with changing the engine RPM? Here you go again with more wishy washy rhetoric. Please stay on one subject and not change your conversation objective every time somebody points out the errors in your logic.
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Ahem i was tought it to be called a reduction gearbox as to spin the prop at a 3-1 ratio from the engine rpm hence the engine idles at 1000 rpm the prop is doing 3000 rpm at the outer edge. :)
That not would be a reduction. :x I take it you failed math miserably. RPM is rpm not matter if is 1 foot or 10ft from the center of rotation.
The Merlin 66 had a 0.477 reduction ratio. An engine turning 3000rpm, the prop would turning at 1431rpm.
Chalenge, please see Item 37, Engine-speed indicator drive.
(http://www.airpages.ru/draw/merlin25.gif)
http://www.airpages.ru/eng/draw/merlin25.shtml
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Ahem i was tought it to be called a reduction gearbox as to spin the prop at a 3-1 ratio from the engine rpm hence the engine idles at 1000 rpm the prop is doing 3000 rpm at the outer edge. :)
Hmmm BulletVI, what you're describing wouldn't be gear reduction but gear addition :) (as Milo has pointed out). It's called reduction for a reason. Think about it for a second. Here's the equation for propeller tip speed:
Vtip = pi * rotational_speed * propeller_diameter
For a 10ft 9in prop like that on the Spitfire at 3000 rpm tip speed would be 1151 mph. At sea level the propeller tip would be rotating at mach 1.51. At little fast don't you think ;)? With a 2:1 gear reduction that brings it to a manageable 1500 rpm which equals 576mph (mach .76 at sea level).
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OOpps yup correct i was basing it on an example from the head not paper oopps
I was thinking of for example a 100 tooth cog rotating at 1000 rpm now to get 2000 rpm you needed a 50 tooth cog connected to the 100 tooth cog which in turn would spin at 2000 rpm as its smaller it has to go twice as fast as the 100 tooth cog to travel the same distance ( bugger )
Slip up on my part was i forgot that prop diameter was bigger than the engine fly wheel. but from the above picture it shows a small output shaft from the engine thus it needs to an encrease in gear ratio not reduction ( bummer Rookie mistake Sorry ) :)
Blast it i could stab myself for that one :(
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Now back to the main topic here guys
Hitech now is the rpm gauge animation out of alinement Or is it an error of some other sort In the rpm gauge of the Spit 1 , 8, 9.
Please look into it
Thankyou BulletVI :)
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Hmmm BulletVI, what you're describing wouldn't be gear reduction but gear addition :) (as Milo has pointed out). It's called reduction for a reason. Think about it for a second. Here's the equation for propeller tip speed:
Vtip = pi * rotational_speed * propeller_diameter
For a 10ft 9in prop like that on the Spitfire at 3000 rpm tip speed would be 1151 mph. At sea level the propeller tip would be rotating at mach 1.51. At little fast don't you think ;)? With a 2:1 gear reduction that brings it to a manageable 1500 rpm which equals 576mph (mach .76 at sea level).
You are a Saint ... Why you even bother to try and educate this kid is beyond me ... and what you have explained to him is way beyond his grasp.
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Im still at a loss to understand why the Spitfire gauge reads up to 12000 RPM. I mean there is no way a Merlin of any description ever hit those revs.
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Im still at a loss to understand why the Spitfire gauge reads up to 12000 RPM. I mean there is no way a Merlin of any description ever hit those revs.
I owned a car that had a speedometer that went to 140 ... it could barely break 100 mph going downhill with a tail wind and in the slip stream of a 45' tractor trailer truck.
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I owned a car that had a speedometer that went to 140 ... it could barely break 100 mph going downhill with a tail wind and in the slip stream of a 45' tractor trailer truck.
http://www.youtube.com/watch?v=EbVKWCpNFhY (http://www.youtube.com/watch?v=EbVKWCpNFhY) :devil
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Bullet learn what wep is in AH, your saying your getting a max of 2750 I.E. you have never pushed the "p" i.e. wep button when at full throttle to get 3000 rpm and max manifold pressure.Or are you complaining about 1 pixel width adjustment?
Also just like before start learning instead of stating complete bolder dash. And go get a refund on that "degree" of yours.
RPM is engine rpm.
Engine rpm and prop rpm are the same thing except for a gear ratio.
RPM lever does not change the pitch on the props , it only changes a preset on a governor. The governor changes pitch via opening an oil valve to increase or decrease pitch to maintain a constant rpm.
The RPM will only vary from preset if the prop has hit mechanical stops at min or max pitch.
some multi engine planes can adjust to about 90 degees and hence feather/stop the props. Single engines planes normally do not have a need for this like multi's.
HiTech
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You are a Saint ... Why you even bother to try and educate this kid is beyond me ... and what you have explained to him is way beyond his grasp.
LOL Slapshot. My secret is I don't read everything he posts :D.
Tango
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http://www.youtube.com/watch?v=EbVKWCpNFhY (http://www.youtube.com/watch?v=EbVKWCpNFhY) :devil
LOL, that was exactly what I was thinking. "It's one louder."
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Also just like before start learning instead of stating complete bolder dash.
He is "learning on the run" ... he finds some little tid bit ... makes what he considers an intelligent post and then everybody else does the work educating him on why he is wrong ... he then picks up a little tid bit from that and the cycle continues.
What amazed me is that after all his various post, people still bite the lure and continue to try and educate the kid when he really doesn't want to learn ... he loves stirrin' the pot and all the attention he gets.
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http://www.youtube.com/watch?v=EbVKWCpNFhY (http://www.youtube.com/watch?v=EbVKWCpNFhY) :devil
:rofl
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LOL, that was exactly what I was thinking. "It's one louder."
Wango Tango!!!!!
:rofl
I miss both you and Slappy in the Arenas these days. I hope the family is doing well for both of you. :rock
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RPM lever does not change the pitch on the props , it only changes a preset on a governor. The governor changes pitch via opening an oil valve to increase or decrease pitch to maintain a constant rpm.
The RPM will only vary from preset if the prop has hit mechanical stops at min or max pitch.
So if you dive a P-51 with RPM set to 3000 the pitch may go to a coarse setting in the dive and still maintain 3000? See my gut is telling me you would have to pull throttle and RPM back. IRL would engine management be very different from the way AH is or not?
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So if you dive a P-51 with RPM set to 3000 the pitch may go to a coarse setting in the dive and still maintain 3000? See my gut is telling me you would have to pull throttle and RPM back. IRL would engine management be very different from the way AH is or not?
its exactly the same IRL. thats how constant speed props work.
heres a great article from a real world website explaining in more detail:
http://www.avweb.com/news/pelican/182082-1.html
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Also just like before start learning instead of stating complete bolder dash. And go get a refund on that "degree" of yours.
HiTech
Would that be the degree in Aerodumbnamics? :rofl
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Like many here have said, the RPM indicator will be mechanically linked to the engine, or somewhere in the gearbox or even an accessory for that matter; their amounts are proportionally dependent on each other. Its all about what numbers are engraved on the RPM instrument to indicate the RPM range that interests you the most. How do you care if the engine revs at 10,000,000RPM when all you need to know is prop RPM which maxes out at 5RPM? (Just an extreme example)
Looked at turbo prop engines? This one is "special". Instead of showing manifold pressure and RPM, it shows the turbine/compressor RPM on one instrument and another one indicates the prop RPM. The turbine RPM is shown in percentage of true RPM while the prop RPM is... ah crap, I just realized the prop in most cases is linked to a freewheeling turbine and does not spin at the same speed the turbine does. I will confuse our student to the point of auto destruction here. Forget it, I give up this is pointless.
(http://home.online.no/~eikarlse/wessex/img00016.jpg)
By the way, at what school and what year did you get your degree in such a complex domain in which you seem to be lacking even the slightest amount of comprehension?
I'm not wasting brain cells on this tread anymore.
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jamdive: why does it read RPM with the engine off? Its not reading engine RPMs.
The engine and the Propeller are mechanically linked through the reduction gear. As such they will always change speed together and in the proportion of the reduction ratio. There is no clutch or fluid coupling that disconnects them. So shutting off the engine will not instantly produce an engine RPM of zero, and as such this test is not proof of which speed is being read by the guage. :salute
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Ok then close the thread
I was just what i thought was pointing out something that may be wrong but as usual nobody listens as your old dogs in here arnt willing to accept new players pointing out possible faults that need adjusting as far as im concerned you lot are just a bunch of ditty old men who don't like it when faults or possible faults are pointed out. You would all rather just Slander other people to protect your favourite toy. It seems that when an old dog points it out and posts with very little explanation you all jump so why don't you all just take a run and jump and wait for the next new player to bully and take the mikey of. As for i now couldnt care less if this game went tits up as i believe that in reality you are all a bunch of retards and fat old men with little willys who sit at a desk all day and do nothing but get fatter and wait around to needle some one.
Good Bye
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Ok then close the thread
I was just what i thought was pointing out something that may be wrong but as usual nobody listens as your old dogs in here arnt willing to accept new players pointing out possible faults that need adjusting as far as im concerned you lot are just a bunch of ditty old men who don't like it when faults or possible faults are pointed out. You would all rather just Slander other people to protect your favourite toy. It seems that when an old dog points it out and posts with very little explanation you all jump so why don't you all just take a run and jump and wait for the next new player to bully and take the mikey of. As for i now couldnt care less if this game went tits up as i believe that in reality you are all a bunch of retards and fat old men with little willys who sit at a desk all day and do nothing but get fatter and wait around to needle some one.
Good Bye
"Well.........bye"
(http://i25.photobucket.com/albums/c62/Masherbrum/curlybill.jpg)
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its exactly the same IRL. thats how constant speed props work.
That cant be kvuo because I have read IRL in WWII pilots had to worry about props running away which we dont.
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That cant be kvuo because I have read IRL in WWII pilots had to worry about props running away which we dont.
It does work like kvuo says in real life.
Props running away (different from "overspeeding") are a result of a failure of the governor which causes the blade pitch to go flat (low pitch) while the engine is still running. The low pitch results in low loading on the propeller which then lets the engine crankshaft spin like crazy because there's not very much loading from the propeller to resist the engine and more than likely leads to all sorts of nice bits of metal and stuff coming loose if you don't shutoff the engine :).
Flakbait and I discussed this and some examples a couple of years ago:
http://bbs.hitechcreations.com/smf/index.php/topic,202353.msg2383945.html#msg2383945
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That cant be kvuo because I have read IRL in WWII pilots had to worry about props running away which we dont.
Props only run away when they drive the engine (and the engine is not operating) and not the other way around. When the prop drives the engine (also known as negative torque), there's no governor imposed limit to the rpm it will reach so the engine tears itself apart when the prop causes the engine to exceed the rpm for which it is rated. Also, there is no oil governing the prop and so it does whatever it wants to with respect to pitch, based on the type of prop you have.
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Okay I guess. The reports I read made it sound as if steep dives pushed more air past the propeller forcing it to rev beyond limits and wreck the gearing. If the only thing to worry about is failed governors then I can see why its not in the game like that but if steep dives do in fact cause this sort of problem I would like to see that in the game just to make things a little bit tougher. :D
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Ok then close the thread
I was just what i thought was pointing out something that may be wrong but as usual nobody listens as your old dogs in here arnt willing to accept new players pointing out possible faults that need adjusting as far as im concerned you lot are just a bunch of ditty old men who don't like it when faults or possible faults are pointed out. You would all rather just Slander other people to protect your favourite toy. It seems that when an old dog points it out and posts with very little explanation you all jump so why don't you all just take a run and jump and wait for the next new player to bully and take the mikey of. As for i now couldnt care less if this game went tits up as i believe that in reality you are all a bunch of retards and fat old men with little willys who sit at a desk all day and do nothing but get fatter and wait around to needle some one.
Good Bye
It's not the fact that you "point" something out ... it's the way you point it out. You make a statement with minimal research and when people (who know what the hell they are talking about) point out the flaws in your statement, you refuse to believe them ... twist it in some other direction rather than say ... "geesh, your right, I didn't really didn't do all my homework on the subject ... thanks for enlightening me".
You say your an "Airframes Engineer" and with that we are all to stop in awe and not question you ? Personally, I doubt very strongly you are an "Airframes Engineer". Any "engineer" who would bring problem resolutions to the table in the manner in which you post on this BBS would not last very long in that profession. Your arguments are completely illogical, lacking in substance, and mostly emotional ... not the signs of a professional engineer.
Want to see how to correctly "point something out" and get results ? ... read this thread and most importantly, the very first post.
Baumer's ... "Gun sight image size analysis" ... http://bbs.hitechcreations.com/smf/index.php/topic,292017.0.html
This guy did all his homework before "pointing out" what he perceived to be a flaw. Presented it with practical examples along with the math/data to back it up. You could tell immediately that he did quite a bit of work and research before starting that thread. That immediately garnered him some respect ... regardless if he was right or wrong. So, with that, and some ongoing constructive discussions, HiTech acknowledged the error and guess what ... he fixed the problem almost immediately.
You want something changed ? ... then bring the "meat and potatoes" to the table.
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Okay I guess. The reports I read made it sound as if steep dives pushed more air past the propeller forcing it to rev beyond limits and wreck the gearing. If the only thing to worry about is failed governors then I can see why its not in the game like that but if steep dives do in fact cause this sort of problem I would like to see that in the game just to make things a little bit tougher. :D
Yes this can definitely happen in a dive as well as you've described. I could quibble with EDO about terminology of runaway props vs. overspeeding props, but no matter in either case the prop and crankshaft are spinning too fast that it wrecks the engine. For a propeller with a working governor you can conceptually overspeed the prop in a dive. This occurs though when blade pitch can longer be increased because it has hit the mechanical stops e.g. the oil piston driving the pitch is at it's maximum.
Before it reaches the mechanical stops however the governor will continue to adjust to keep RPM constant. As the airplane increases in velocity, the loading on the propeller lessens due to a lower relative blade aoa thanks to the increasing forward velocity. Lower blade aoa means lower torque loading on the propeller therefore it spins faster. This increases RPM on the crankshaft which changes the centrifugal force on the fly weights in the governor which causes the governor to pump more oil to increase blade pitch to increase the propeller loading. More loading on the propeller makes it harder for the engine to turn the prop thus slowing the RPM back down to the desired setting. That's what John Deakin's article that kvuo pointed out talks about.
Here's a schematic of the Hamilton Standard Hydromatic that many of our airplanes in AH used in real life and how it addresses the overspeeding I was describing in the paragraph above.
(http://thetongsweb.net/images/OVERSPEED_2.jpg)
There is some increase in forward velocity however where we reach the mechanical stops. When this happens the governor can't increase the pitch of the propeller anymore to adjust for the lower propeller loading. Since the power loading keeps decreasing in this case with increasing velocity the prop and the crankshaft spins faster and faster. At some point the engine can't handle it any more and blows chunks :). As to modelling this, I have no idea if AH has an RPM limit on planes before the engine fails. Bear in mind though that in this particular case you can easily avoid ovespeeding the propeller by simply closing the throttle.
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Ahem what type of merlin engine is in the MkVIII Spit in game as from reading this web page i hope its the Spitfire LF VIII
With the merlin 66 engine capable of
1720bhp @ 5750 feet
1595bhp @ 1600 feet
It sounds powerful SLURP :) :t :devil
http://www.spitfireperformance.com/spitfire-VIII.html
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....and to think someone said "Goodbye" in this thread and is still posting.
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....and to think someone said "Goodbye" in this thread and is still posting.
I was angry and have now vented it :)
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Ahem what type of merlin engine is in the MkVIII Spit in game as from reading this web page i hope its the Spitfire LF VIII
it is indeed a 66 in our LF VIII :)
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There is some increase in forward velocity however where we reach the mechanical stops. When this happens the governor can't increase the pitch of the propeller anymore to adjust for the lower propeller loading. Since the power loading keeps decreasing in this case with increasing velocity the prop and the crankshaft spins faster and faster. At some point the engine can't handle it any more and blows chunks :). As to modelling this, I have no idea if AH has an RPM limit on planes before the engine fails. Bear in mind though that in this particular case you can easily avoid ovespeeding the propeller by simply closing the throttle.
Yes but the point is there are quite a few that dont so if Hitech returns to this thread...
+1 Please invoke the governor of dweebs for us all! :D
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You know what would really hurt people and thats if the wep wouldnt automatically cut out after 4 minute's. I mean imagine it all the wep dweebs suddenly go clonk clank pur pur pur stop :lol
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There is some increase in forward velocity however where we reach the mechanical stops. When this happens the governor can't increase the pitch of the propeller anymore to adjust for the lower propeller loading. Since the power loading keeps decreasing in this case with increasing velocity the prop and the crankshaft spins faster and faster. At some point the engine can't handle it any more and blows chunks :). As to modelling this, I have no idea if AH has an RPM limit on planes before the engine fails. Bear in mind though that in this particular case you can easily avoid ovespeeding the propeller by simply closing the throttle.
I've never lunched an engine in AH by over speeding in WW2 planes, but have done it in the WW1 planes.
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Yes this can definitely happen in a dive as well as you've described. I could quibble with EDO about terminology of runaway props vs. overspeeding props, but no matter in either case the prop and crankshaft are spinning too fast that it wrecks the engine. For a propeller with a working governor you can conceptually overspeed the prop in a dive. This occurs though when blade pitch can longer be increased because it has hit the mechanical stops e.g. the oil piston driving the pitch is at it's maximum.
Yes, what you say is fact. No disputing that. I believe (but I may be incorrect) that in real aircraft such as those modeled in AH, the dive speed (Vne?) is partially determined by the prop loads/forces and airframe loads/forces (not including compressability). We do not have such an airspeed restriction on the airplanes in AH, save the fact that some aircraft will experience structural failure when the airspeed gets too high (usually in a dive and without pulling G). In oher words, there is no Pilot's Operating Handbook for the aircraft in AH telling us what airspeed restrictions and such.... That's too much info for the game dynamic.
Regarding the overspeeding propelllor/runaway propellor... I don't follow but suffice to say that in my understanding of a constant speed prop, an overspeed only results in governor flyweights raising the oil valve due to the increased centrifugal force on said flyweights (provided the prop is in the constant speed range). As you've said, it is a temporary condition that results in blade angle increase and more load on the engine, slowing the rpm back to where it's been set to. Runaway prop is, in my minds eye, a propeller that cannot be feathered after an engine is shut down (multiengined aircraft) and consequently the torque and rpm's get to the point where the reduction gearcase bolts yield under the shear forces and there goes your prop/reduction gearcase off into the wild blue...not to mention what it does to the rest of the engine.
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WW1 has fixed pitch props, that's why. The more airflow pushes the engine past its limit, vs. adjusting pitch to keep the spin rate constant. Hence "constant speed" propellor....
P.S. AH has over-speeding sort of built in. I've noticed many times in many different planes an inability to reduce RPM at certain speeds, until the airspeed has slowed enough that it takes effect.
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Regarding the overspeeding propelllor/runaway propellor... I don't follow but ........Runaway prop is, in my minds eye, a propeller that cannot be feathered after an engine is shut down (multiengined aircraft) and consequently the torque and rpm's get to the point where the reduction gearcase bolts yield under the shear forces and there goes your prop/reduction gearcase off into the wild blue...not to mention what it does to the rest of the engine.
Usually the context I see runaway props described is when the governor fails with the engine still running vs. how you described engine shut off and prop windmilling. For instance here's the procedure out of the P-51D manual: (mentions the POH overspeed rpm's)
(http://thetongsweb.net/images/p51runaway.jpg)
But I've also seen "runaway prop" used in other ways too. Anyway just ignore my mumbling about the meaning of the terms :). Totally unimportant! It's holdover from my work- infact today we were debating the precise definition of the meaning of "facility" vs. "plant" as information objects. Is a facility a plant or a plant a facility? Is a plant always a facility, but not all facilities plants?? etc. etc. :cry
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You know what would really hurt people and thats if the wep wouldnt automatically cut out after 4 minute's. I mean imagine it all the wep dweebs suddenly go clonk clank pur pur pur stop :lol
What is a WEP dweeb ?
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It's holdover from my work- infact today we were debating the precise definition of the meaning of "facility" vs. "plant" as information objects. Is a facility a plant or a plant a facility? Is a plant always a facility, but not all facilities plants?? etc. etc. :cry
UGH ... a plant cannot be a facility ... a plant in something that grows in the ground !!! ... bunch of dummies !!! ... :D
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And here I was thinking that aircraft engines worked on magic and dreams :D
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And here I was thinking that aircraft engines worked on magic and dreams :D
I've always assumed they worked on magic smoke just like modern electronics. Ever let the magic smoke out of your computer or surround receiver? Stopped working didn't it? :)
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I've always assumed they worked on magic smoke just like modern electronics. Ever let the magic smoke out of your computer or surround receiver? Stopped working didn't it? :)
:rofl ... now that's funny !!!
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I've always assumed they worked on magic smoke just like modern electronics. Ever let the magic smoke out of your computer or surround receiver? Stopped working didn't it? :)
I just assumed it was British-Leyland cars that ran on magic smoke too, frequently they seem to become overfull and need to leak some out.
:)
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IIRC a common failure in B17s was that if the governor broke up the blades would go against fine pitch stop in governor and the propeller would severely overspeed and eventually detach itself from the engine and there was nothing you could do about it.
http://www.daveswarbirds.com/b-17/wings.htm
-C+
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What is a WEP dweeb ?
They are the ones who use it even after its cut out :)
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See Rule #4
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Thanks for the education gentlemen. This thread was highly informative.
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See Rule #4
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See Rule #4
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whaaa...
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Calling it.
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should I throw up the signal guys?
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should I throw up the signal guys?
Go for it. I hear INcomINg.
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See Rule #4
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Runaway prop is, in my minds eye, a propeller that cannot be feathered after an engine is shut down
Not really related to feathering, but if you're unable to feather you get the same end result.
In the B-17 or B-24 the procedure if you have a runaway prop is to first attempt to reduce RPM by using the prop control, if that doesn't work you retard the throttle. If still overspeeding you push the feathering button in until RPM returns to normal level then pop the button out -- repeat until you either secure the engine or land. Once had to do that in the B-24. PITA.
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Theres a feathering button on the B24? I dont think mine is equipped with one! :devil
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I dont think mine is equipped with one! :devil
I would hope not, it should have four of them. <G>