Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: F4UDOA on January 30, 2001, 09:12:00 AM
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Been doing a little reading into WEP in different A/C. Apparently there is a couple of discrepancies with the tech specs.
In AH the F6F-5 has 5 minutes of WEP.
Actual available WEP in the F6F-5 was 15minutes. Check this PDF for verification.
http://214th.com/ww2/ (http://214th.com/ww2/)
Also the F4U-1D has 5 minutes of WEP in AH.
Actual data has it at 8.5 minutes of water injection.
(http://www.geocities.com/slakergmb/1a324170.jpg)
If anyone has similar documents for the P-47, P-51 and P-38 please post a link or email them to me. From the P-38L pilots manual it looks as if there is 5 minutes of WEP but a more detailed document would be better.
Just as a reference the P-47 water is probably way off.
here is the available water and duration in AH and real life. (Gallons from AHT)
F4U-1D
Gallons=90
Duration=8.5minutes
Aces High duration=5min.
F6F-5
Gallons=119
Duration=15minutes
Aces high duration=5min
P-47D-25
Gallons=248!!!
Duration=N/A
Aces High=5min<==probably wrong
Note: The FW190A8 does have a full 10minutes of WEP.
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Nic data F4UDOA; you're doing a really fine job. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Turn your attention to the LW aircraft, please (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif).
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Baron Claus "StSanta" Von Ribbentroppen
9./JG 54 "Grünherz"
(http://store4.yimg.com/I/demotivators_1619_3845234)
"I don't necessarily agree with everything I think." - A. Eldritch
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Originally posted by StSanta:
Turn your attention to the LW aircraft, please (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif).
Santa, with all due respect, not an ounce of pity falls on those who claim something is porked, but has no data to back it up.
Do the research yourself, you'll not only learn something, but may actually break the mold of special interest whine associated with it.
<S> F4UDOA, great stuff, now where is Pyro's/HT's reply?
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StSanta,
I did look at the FW190A-8. Funny thing I noticed was this.
The FW190F-8 had a third fuel tank in addition to the two in an A-8. This third tank could be filled with GM-1(nitrous Oxide) instead of fuel for better performance. I guess this is the reason for the recent out cry for the F-8 in AH.
We should call that post "Secret Agenda of the Luftwabbles" (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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There should be a WEP multiplier just like the fuel multiplier. For some planes to have a WEP time as long as their fuel time is ridiculous.
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F4DOA... you are da man. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
With water injection, could you run it consistently intil it ran out, or would the engine overheat first or have other problems?
Now as for the Jug, .... oh yeah bring me more WEP. The Jug WEP seems really weak compared to how it was back in WB in the old days. Do you have any speed specs for the Jug in Mil. vs. WEP?
------------------
Lephturn - Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com (http://www.flyingpigs.com)
"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"
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well in AH u never run out of wep ability really, just cool down and u got wep again.
but in RL theyy had limited wep, once they
run out of water, meth, o what ever they used, they had no wep left except for over 100% power setting.
we need 2 stage wep in AH, 1st stage is just using higher then 100% power setting, 2nd stage would be using the water injection or meth....ect
Whels
Originally posted by F4UDOA:
StSanta,
I did look at the FW190A-8. Funny thing I noticed was this.
The FW190F-8 had a third fuel tank in addition to the two in an A-8. This third tank could be filled with GM-1(nitrous Oxide) instead of fuel for better performance. I guess this is the reason for the recent out cry for the F-8 in AH.
We should call that post "Secret Agenda of the Luftwabbles" (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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F4UDOA, AFAIK, all 190A8 had this extra tank able to contain enough methanol/water mix for 40 mins of boost usage in periods of no more than 10 mins with resting periods of 5 mins. Suppose these numbers are also applicable to petrol injection system or GM-1.
So, if the F4U has a water tank for 8 mins of WEP, 190A8 has one for 40 mins.
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Lephturn,
Most Jug data I have is from AHT. I just can't find much data for Army Air corps birds like you can for Navy birds. It's very strange considering how much more there has been written about the AAF than the Navy/Marines. The actual documents are much harder to come by. In any case the Jug seems to suffer more from the lack of boost than other PW-2800 birds. On the other hand it also gets more out of it when it has it to use. The P-47 seems to gain almost 25% climb gain with WEP than Military power as compared to the F4U and F6F that gain only about 10%. However it is obvious based on the amount of water in the P-47 that the designers were aware of this gain.
Also keep in mind that the water injection on American birds was not the same as the German GM-1 which was nitrous oxide. The water was designed purely to cool cylinder head temperatures when operating at higher manifold pressures and higher temperatures. The American answer to that would have been to simply run at a higher octane mix alla 115/130 fuel. The Brits also did this.
Whels1,
I am embarrassed to say I did not know this. I thought when you ran out you were out. I didn't think there was a cool down period built into to the FM. I will check this out.
Later
F4UDOA
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Mandoble,
I stand corrected<S>.
I misread one sentence that changed what I was reading. The tank was 25.3 gallons according to Smithsonian institute press.
Further
empty weight 6,750lbs
Loaded weight 10,725lbs
Horsepower=1,730
Armament
Fuselage- 2 13mm MG 131 machines guns
Wings- 2 20mill MG 151 cannon
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F4u- yes I think whats modeled is the engine's specification of how long they were supposed to be run at that setting. So IRL the P-47 had tons of coolant in the tank the engine was specified to only be run at 5 minutes per use. (and I am sure the pilots cared about THAT in combat!)
Pyro posted a page about the engine in the F4U I believe, in a thread on engine weardown where people were asking engines to "break" if left at 100% a whole flight. The book listed that the engine was "rated" to be run only 5 minutes at the WEP setting to prevent premature wear. I think these are the settings he used for these things.
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F4UDOA
"Also keep in mind that the water injection on American birds was not the same as the German GM-1 which was nitrous oxide. The water was designed purely to cool cylinder head temperatures when operating at higher manifold pressures and higher temperatures. The American answer to that would have been to simply run at a higher octane mix alla 115/130 fuel. The Brits also did this."
You confused the heck outta me with that paragraph.
Water injection on allied planes = German MW30/MW50
Used to prevent detonation at high boost.
GM-1, HA-HA, Goerings brew: Nitrous Oxide. Supplys Oxygen for high altitude operation.
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Chisel,
I'm not saying that they are the same thing. I am saying that when looking for higher performance at alt the Americans took a different route than the Germans. I am very familiar with the use of water to cool and prevent premature detonation, therefore allowing higher manifold pressures. Increasing the octane rating in the fuel does effectively the same thing(not detonating prematurely at lower pressure).
Nitrous is another story. I am not as familiar with it's application.
As far as combat range I would suggest looking harder at the chart listed above states under the combat section of the range chart. Combat 20minutes at 15,000ft. 8.5 minutes WEP, 11.5 minutes Mil. power and descend. I belive these are a series of actions that are quite literal giving you the max combat range with variance listed below for faster cruise time.
Sorrow,
The P-47 had a ton of water for cooling at higher temperatures/manifold pressure. I didn't list the limit on consecutive use because I don't see it. But if you think WW2 fighters and there pilots did not exceed the limits for premature wear you are mistaken. I have a book on fighter design that clearly states that air cooled engines specifically were operated beyond what for a liquid cooled engine would be acceptable.
In fact Charles Lindbergh flew combat missions in the south pacific showing pilots how to run there engines very lean/hot to maximize range. Mainly because they were "built to take it".
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The FW190F-8 had a third fuel tank in addition to the two in an A-8. This third tank could be filled with GM-1(nitrous Oxide) instead of fuel for better performance. I guess this is the reason for the recent out cry for the F-8 in AH.
If you look carefully enough you would see that AH A-8 already has three fuel tanks unlike A-5 which has two.
The extra tank (EXT) is used as fuel tank in AH. It could have been filled with MW 50 (methanol 50% / water 50%) liquid but since MW 50 was not fitted to most A-8's it was used as fuel tank.
GM 1 system contains high pressure liquid nitrous oxygen and you cannot store it in normal fuel tank like EXT in A-8! It was stored in small spherical high pressure tanks or normal cylindrical high pressure tanks.
F-8 used emergency fuel injection to obtain extra power at altitudes below 1000 m (3280 ft) by injecting normal fuel to supercharger inlet, cooling piston heads and cylinders and causing same effect as MW 50.
We should call that post "Secret Agenda of the Luftwabbles"
No you should not if you don't know what you are talking about...
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jochen Gefechtsverband Kowalewski
Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.
Sieg oder bolsevismus!
[This message has been edited by Jochen (edited 01-31-2001).]
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Jochen,
I have already said that the GM-1 tank was available in the A8 as well. The tank was 25.3 gallons. So I guess I do know know what I'm talking about.
Try reading the thread before criticizing.
[This message has been edited by F4UDOA (edited 01-31-2001).]
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earlier R2800's used different heads and bearings and the corsair was designed before the Hellcat. The Hog was designed to run 10 minutes (topped off with water) which seemed safe. The "c" series engines were better for cooling even though there had been no problems with the earlier engines. later Hogs use the c series.
The Jug was suppossed to run 12-15 minutes. It was turbo supercharged and so probly used a higher rate pump for the water. Jugs often came home with dry water tanks.
All PW R2800's consumed water and fuel depending on engine condition/tune. It was a simple adjustment to "up" the boost in the PW. I suspect that the 19 year old hot rodders in the field did this quite often.
lazs
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I have already said that the GM-1 tank was available in the A8 as well. The tank was 25.3 gallons. So I guess I do know know what I'm talking about.
Yes, there was possibility to put GM 1 system to A-8 but it required HIGH PRESSURE gas bottles, not a simple fuel tank as you suggest. I would like to see you trying to force high pressure liquid nitrous oxygen to a ordinary thin walled fuel tank.
109's that had GM 1 had to use cylindrical high pressure bottles located on left wing root to contain the gas, why not 190?
There is a myth that A-8 can have either GM 1 liquid, MW 50 liquid or fuel in EXT tank. GM 1 part is roadkille. GM 1 required HIGH PRESSURE gas bottles and that EXT tank is not a high perssure gas bottle.
I'm still not convinced you know what you are talking about.
Try reading the thread before criticizing.
If you try not to jump into conclusions without knowing the facts. (ie. F-8 having GM 1 boost, must be lufwaffe conspiracy to get one)
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jochen Gefechtsverband Kowalewski
Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.
Sieg oder bolsevismus!
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Of course GM 1 used nitrous oxide, not nitrous oxygen as I stated but english is not my native language.
But I am still very sure that EXT tank in A-8 was not capable of storing GM 1 liquid.
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jochen Gefechtsverband Kowalewski
Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.
Sieg oder bolsevismus!
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Just checked two Nowarra's books and they mentioned that Ta 152H carried GM 1 pressure bottles and A-8 EXT tank could be replaced by smaller tank capable holding GM 1 nitrous oxide.
I think case is closed on this one.
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jochen Gefechtsverband Kowalewski
Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.
Sieg oder bolsevismus!
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Jochen,
I am reading this directly from a book from the Smithsonian press called "FW190 Workhorse of the Luftwaffa" which details a FW190-F8 and has a note on the bottom about the third tank being available on A-7 and A-8 models as well expressly for carrying GM-1.
It was a 25.3 gallon tank. No other mention of the tanks condition(pressurized or unpressurized) is mentioned. Although being only a 25 gallon tank I don't imagine that it would have served much use as a standard fuel tank being so small.
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25 gallons is an enormous amount of Nitrous Oxide...would prolly excede the fuel capacity easily depending on what pressure is used.
Racing NO2, in 1 Gallon bottles last for a duration of 3 hours at 10lb shots, to give you an idea.
- Bess
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Here's another thought on the water injection. Wouldn't it also increase charge density and mass flow rate through the engine. Also water in the right amount could act as an oxidizer during combustion couldn't it? Isn't there something similar used on jet aircraft? On the nitros, the only way I've ever seen it stored was in a pressurized bottle. I always assumed it was so in the planes. 25 gal, as Jigster said, is a lot of nitros. I think a 600cid+ engine turning 8000rpm in a dragster will use about 2/3 the amount of nitros as a 1600cid 4000rpm. With that ruff estimate and Jigsters estimate a 25 gal nitros tank will give around 100 hrs of boost time. I'm just ruffing these calculations DON'T PANIC if you think I'm wrong just tell me why. I'm getting so sick of people on here freaking out if you make a SWAG and it's wrong. It's a guess.
PS Jigster = Jeg's maybe? (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
[This message has been edited by Jimdandy (edited 01-31-2001).]
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Nitrous oxide is used to raise the engines critical altitude. Nothing to do with its use in Dragsters. To my knowlege Fuel systems werent setup to add the extra fuel on the deck.
From Janes: Ta152b (Db603) injected at 13.2 lbs/min.
Edit; The germans also experimented with pure O2 but I figure it was consided a little too dangerous to haul that much Compressed O2 around (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
[This message has been edited by chisel (edited 01-31-2001).]
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Nitrous Oxide does a few things -- namely, when on the compression stroke, when N02 raises above 570 degrees, the molecules break up releasing oxygen. As the NO2 breaks down, it boils to a much lower temperature within the chamber, dropping charge temp way down, providing a more dense air/fuel mixture for more efficent burning. The boiling effect of the NO2 also creates a "steam"-like effect that delievers more power by dampining the effect of the extra fuel burn, yet increases cyclinder pressure creating more power and torque.
GM-1 will work it's best a high altitude where the oxygen can be put to use -- but, don't be fooled into thinking nitrous Oxide doesn't have much effect at lower altitudes. When compared to MW50, GM-1 provides massive power gains (or restoration if you will) at altitude, yet on the deck the MW50 works better for overboosting. But the NO2 does reduce engine temp quite a bit so the super charger works more efficently, but the steam (expansion on vaporization) effect and combustion buffer of menathol/water allows for more power and higher boost.
the GM-1 (or Nitrous Oxide in general) however, does not reduce engine life to any great extent regardless of application because of the tremendous cooling effect.
- Bess
Btw Jim, I have '79 Bronco with a 1 Gallon NOS, 10,000RPM brand. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Cool Bronco Jigster.
I do think that nitrous and MW will hurt an engine that hasn't got the proper low end (connection rods, bearings, and main bearings) and oiling system. Take a look at my post "Perk engine for the Spit." The Miss Budwiser was able to get 4,000hp out of a RR Griffon. One of the main things they had to improve was the oiling system. Back then (WWII) they didn't have as much knowledge on oiling systems as we have today. Also the quality of the oil they used wasn't as good. It tended to brake down under thermal stresses faster. It is possible that the original designs for these engines never were intended to support that kind of loading. They may not have had time to retool for a new block that would fit the size of main bearings needed for prolonged high rpm and boost. An example in the automotive world is the Pontiac's. They designed the Pontiac bearings to wide to handle rpm's greater than about 5,500. The oil pump couldn't keep up the volume needed to cover that much area at higher rpm. On top of that Pontiac used cast rods. On top of that their lifter galley was weak. Under high rpm the block would flex enough to crack the lifter galley. That's why they made the SD 455. It fixed all of those problems plus added better flowing heads. These are the factors involved in the short duration of use I bet. The piston speed comes into play here. For the old flat head engine with cast rods and dipper cranks you didn't want the piston speed to be greater than 2500ft/min. To find the piston speed (PS) use this formula:
PS= stroke (in inches) X rpm/6. (This will give you PS in ft/min)
I wouldn't be surprised that the piston speed of all of these engines was close to that. I wouldn't be surprised that the were trying to limit the period of time the engine ran at piston speeds higher than 2500ft/min. This would also reduce stress on the oiling system. When ever you increase cylinder pressure the stresses on the rods, crank and bearings go up. On top of that you increasing the rpm. One more thing might be the ability for the top end (cam, push rods, rocker arm) to handle the higher rpm. In a modern "stock" engine the piston speed can safely reach 3500ft/min. Look at what they do to a racing engine to get it to handle higher than stock loads(I'm sure you know). They add 4 bolt mains, steel or aluminum rods, better bearings, Steel crank, cross drill the crank for 360 degree oiling. All of those things were being learned back then.
PS For those that don't know. Steel cranks are added because they aren't as brittle as cast iron. Steel is more flexible. Steel and aluminum rods will absorb more the impact of combustion with out transferring it to the crankshaft. Aluminum is also light so the energy needed to move it is less. The problem is the aluminum rods aren't as durable. That's one of the reasons you see the top fuel cars tearing into there engines ever couple races to change rods. If they don't they get an expensive ride. Even with those precautions they still have them come apart without notice.
[This message has been edited by Jimdandy (edited 01-31-2001).]
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I am reading this directly from a book from the Smithsonian press called "FW190 Workhorse of the Luftwaffa" which details a FW190-F8 and has a note on the bottom about the third tank being available on A-7 and A-8 models as well expressly for carrying GM-1.
I did read details from two Nowarra's book about Fw 190 and he said that normal A-8 and F-8 EXT tank could carry MW 50 or normal fuel or be REPLACED by smaller GM 1 bottle system.
It was a 25.3 gallon tank. No other mention of the tanks condition(pressurized or unpressurized) is mentioned. Although being only a 25 gallon tank I don't imagine that it would have served much use as a standard fuel tank being so small.
If it carries nitrous oxide it definitely needs to be a high pressure bottle. How much would 25.3 gallon bottle weight if it was made out of high strenght steel to be able to stand the pressure exceeding 1000 PSI? It would weight a lot!
If you have flown AH A-8 you would know that EXT tank is very small and it empties very fast, it is a small one. But it is an internal tank and sometiems made drag inducing external drop tank unneccessary.
Nitrous oxide for dragsters or aenesthetic purposes are stored in high pressure bottles and I am sure it would have been stored in same way in Fw 190, not in a thin walled fuel tank.
Common sense says that you cannot use same tank for storing fuel and high pressure liquid gas.
I say that EXT tank in Fw 190 cannot store nitrous oxide for GM 1. Only few test 190's were equipped with GM 1 and they most propably used similar high pressure bottles as 109's. F-8 definitely did not use GM 1 because GM 1 is intented as high altitude boost and F-8 was a low altitude ground attack plane.
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jochen Gefechtsverband Kowalewski
Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.
Sieg oder bolsevismus!
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Oh, the P47 carried 30 gallons of water. F6 was 16 gallons. Hog was 10 1/2 gallons.
lazs
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Damn I'm good some times. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif) niklas posted some very good info on the Bf190F4 that seems to conferm my assumtion about piston speed being the critical factor in the WEP time.
Bf109F DB601E:
Stroke = 6.3in
Cruising speed = 2300rpm
WEP = 2700rpm
Useing the formula above:
Cruising speed PS = 2415 ft/min
WEP PS = 2835 ft/min
I looks like they are limiting the time the engine runs at piston velocities over 2500 ft/min. I'm assuming that Cruising speed is less than Military. If so I wouldn't be suprised that Military is 2380rpm = PS of 2500 ft/min.
PS If you look at my post on Perk engine for the Spit you will see that the RR Griffon was running a maximum piston speed of just over 3000 ft/min. This shows me that the Griffon was a more modern engine than the DB601E. The piston speed of the Griffon is closer to the modern standard of 3500 ft/min max.
[This message has been edited by Jimdandy (edited 02-06-2001).]
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PS If you look at my post on Perk engine for the Spit you will see that the RR Griffon was running a maximum piston speed of just over 3000 ft/min. This shows me that the Griffon was a more modern engine than the DB601E. The piston speed of the Griffon is closer to the modern standard of 3500 ft/min max.
[This message has been edited by Jimdandy (edited 02-06-2001).][/B]
Jumo213: 3250 RPM (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
Don´t forget that RR engines were always much closer to the limit of stress than german engines. I.E the german analyzed a Merlin X or XX engine and came to the conclusion that it offered a safety factor of ~1,6. The early JumoA had a safety factor of ~2,4 (crankshaft or other mechanical components, i don´t have the report at home). That means the merlin engines didn´t offer a possiblity to increase power with water-injection, because they were already running very close at the structural limit. That was different for the german engines.
GM-1 is N2O not NO2 afaik
niklas
[This message has been edited by niklas (edited 02-07-2001).]
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It is not true to say that Rolls Royce engines could not be tuned to produce higher power, as the 'Miss Bud' example demonstrates extreme tuning.
It is also well-documented that Merlin and Griffon engines were both modified to run 150 octane fuel at manifold pressures of up to 25lb, as compared to the standard 18lb on 100 octane fuel. This is directly analagous to the use of water- or methanol/water-injection.
However that the Merlin and Griffon were both far more highly tuned than their German counterparts is undeniable. One only has to compare their specific outputs to see that.
[This message has been edited by Bombjack (edited 02-07-2001).]
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Two things to think about:
1. Shouldn't our fuel multiplier affect our WEP times?
2. If we don't "burn" water when using WEP, I'm carrying around a bunch of extra weight in my Jug! If I'm out of WEP, It would be nice if I got rid of a few hundred pounds of water too. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif) (What's H2O? 9 Lbs/ Gallon?)
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Lephturn - Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com (http://www.flyingpigs.com)
"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"
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Ever seen a 6 inch piston which was damaged because continuous overheat thus followed by detonating?
Its not a pretty sight (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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Originally posted by Bombjack:
It is not true to say that Rolls Royce engines could not be tuned to produce higher power, as the 'Miss Bud' example demonstrates extreme tuning.
It is also well-documented that Merlin and Griffon engines were both modified to run 150 octane fuel at manifold pressures of up to 25lb, as compared to the standard 18lb on 100 octane fuel. This is directly analagous to the use of water- or methanol/water-injection.
However that the Merlin and Griffon were both far more highly tuned than their German counterparts is undeniable. One only has to compare their specific outputs to see that.
[This message has been edited by Bombjack (edited 02-07-2001).]
The question is not only whether you can tune the engine, but also how long you can run it with that overboost. Mechanical components are often designed for a certain lifetime. If your car-engine is designed for 500.000miles, than it would be a little bit heavier (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif).
I.e the world record engine of the me209 in the 30ies: A db601 engine without manifold pressure limiter. It put out ~2500-3000hp, but this only for ~5 minutes, afterwards it was destroyed (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
niklas
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Lephturn,
I don't know how we would do a fuel multipier vs WEP time ratio.
Consider this. A P-47 has roughly twice the range of a Me-109, say 8 hours vrs 4 hours (Just a guess). If the Jug has 20 minutes of total WEP vrs 10 minutes for the 109 then the multiplier will reduce all fuel burn times at the same rate.
Imagine that the fuel multiplier is *16.
P-47 fuel duration
8 hours / 16 = .5 or 1/2 hour of total flight time on internal fuel.
WEP=.20 / 16 = 1.2 minutes(not very much fun time)
Me109 Fuel duration
4 hours / 16 =.25 or 15 minutes
WEP time= .1 / 16 = .6 minutes(about 40 seconds)
To reduce the WEP at a similer rate wouldn't leave you with enough for a single encounter. Unless of course a different multipier is used for WEP. But regardless of what number is used it will reduce an already short period of time to a small blip almost not worth having.
The one irregularity in the current system is the WEP time of the FW190A8. It has 10 minutes of time (Don't know if it is consecutive time) compared to other birds, P-47, F4U, and F6F which all had capacity for more than 5 minutes as well as a much longer range on internal fuel. I think the only solution would be to either make all WEP times historically accurate or reduce WEP evenly across the board at a equal rate.
BTW, all of my previous comparisons were theoretical times, not historic. So turn of your flame throwers.
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The question is not only whether you can tune the engine, but also how long you can run it with that overboost. Mechanical components are often designed for a certain lifetime. If your car-engine is designed for 500.000miles, than it would be a little bit heavier .
I.e the world record engine of the me209 in the 30ies: A db601 engine without manifold pressure limiter. It put out ~2500-3000hp, but this only for ~5 minutes, afterwards it was destroyed (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Very good point <Salute>
The 150-octane Spits that variously chased V1s and low-level 190 fighter-bombers were indeed noted for having higher servicing requirements (in the case of the XIV, considerably higher), but these requirements were not so strenuous that the RAF didn't field several squadrons of such planes for their specialist purposes.
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Yep, I see your point F4UDOA.
I think it might be better to just leave the WEP times at realistic levels, regardless.
However, I would like to be able to lose the 300 lbs of water I'm carrying around in my Jug. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif) It would be pretty much a waste of HT's time I'm sure.
Just give me "Lucky" as a perk plane. <G>
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Lephturn - Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com (http://www.flyingpigs.com)
"A pig is a jolly companion, Boar, sow, barrow, or gilt --
A pig is a pal, who'll boost your morale, Though mountains may topple and tilt.
When they've blackballed, bamboozled, and burned you, When they've turned on you, Tory and Whig,
Though you may be thrown over by Tabby and Rover, You'll never go wrong with a pig, a pig,
You'll never go wrong with a pig!" -- Thomas Pynchon, "Gravity's Rainbow"
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Originally posted by Staga:
Ever seen a 6 inch piston which was damaged because continuous overheat thus followed by detonating?
Its not a pretty sight (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
Yes it's so cool. I've taken apart some really cool blown engines both gas and diesel. I think the diesels come apart with the best distruction. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif) I had a connecting rod out of a GM Detroit diesel locomotive that I used as a door stop for a long time. It had thrown that rod and it was all twisted. It was cool. There was this big hole in the side of the block you could almost walk thru. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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Originally posted by niklas:
Jumo213: 3250 RPM (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
Don´t forget that RR engines were always much closer to the limit of stress than german engines. I.E the german analyzed a Merlin X or XX engine and came to the conclusion that it offered a safety factor of ~1,6. The early JumoA had a safety factor of ~2,4 (crankshaft or other mechanical components, i don´t have the report at home). That means the merlin engines didn´t offer a possiblity to increase power with water-injection, because they were already running very close at the structural limit. That was different for the german engines.
GM-1 is N2O not NO2 afaik
niklas
[This message has been edited by niklas (edited 02-07-2001).]
Good point niklas. I had assumed that the RR engineers had designed a stronger engine. Actually what they were doing was running it closer to the limit. As for the Miss Bud engine you have to look at the trouble they went to to get it to push that kind of horse power. The fuel was top fuel dragster fuel. It wasn't expected to run as long. The Miss Bud enigine can be looked at as the design limit. It couldn't be used in combat as anything more than an Me 163 type of a plane. Fly up shoot and land before the engine blows. But it would be cool to see what it would do in a Spit. Man I loved hearing those RR's out on the river. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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The Merlin was modified to run on 150 octane at 25 lb boost
It was also tested safely at 30 lb boost (2200hp) and endurance tested at 36lb boost and water injection, which produced 2780hp
Merlins were tested for 100 hours continuous at 18lb boost (ie wep for normal Spit IXs)
[This message has been edited by Nashwan (edited 02-07-2001).]
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Jimdandy,
Do you have the stroke information on the PW-R2800??
I have never seen the cruise speeds defined that way. Engineering is a wonderful thing. There is an answer for things that you didn't even know that there was a question.
Thanks
F4UDOA
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In short:
In the original Fw190A-7 bis A-9 Fleugzeug-Handbuch it says:
Ab Baureihe A-8 kann hinter Spant 8 entweder ein GM-1-Behaelter (85 Liter Inhalt) oder ein Zusatzkraftstoffbehaelter (115 Liter Inhalt) eingebaut werden.
danish
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Originally posted by F4UDOA:
Jimdandy,
Do you have the stroke information on the PW-R2800??...
F4UDOA
No sorry F4UDOA I don't. I got the figures for the 109 off of niklas's post and I just happend to find the Griffon info on a web search.
PS You know I think someone posted that about a month ago. I'll see if I can find it.
[This message has been edited by Jimdandy (edited 02-07-2001).]
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F4UDOA Here's some GREAT info on the R2800 plus cool photo's of an F4U restoration:
http://www.bootstrapaircraft.com/r2800-18.htm (http://www.bootstrapaircraft.com/r2800-18.htm)
It say's it has a 6.0" stroke and in the final version turned 2,800 rpm. Thus the piston speed was 2800 ft/min. They give some very good information on the modification that were made to the engine to make the final version. As I said above, there are many things that can limit the WEP time. Piston speed is one of the most critical but there are others. This document has some very good info in it on what limited the horse power of the R2800 in it's different versions.
PS Oops the first link wont take you to the F4U restoration but this will:
http://www.bootstrapaircraft.com (http://www.bootstrapaircraft.com)
[This message has been edited by Jimdandy (edited 02-07-2001).]
[This message has been edited by Jimdandy (edited 02-07-2001).]
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JimDandy,
You mentioned the piston speed being 2800 FPM if the RPM was 2800. How is this possible? If the stroke is 6" and the RPM's are 2800 shouldn't I multply those two numbers??
I am trying to go by your previous post to figure out what the calculation for piston speed is.
BTW, from the pilots manual of the F4U-1 PW-R2800-8W B series.
Combat RPM 2700
Military RPM 2700
Normal (max continuous) RPM 2550
Max cruise RPM 2150
Thanks
F4UDOA
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Originally posted by F4UDOA:
JimDandy,
You mentioned the piston speed being 2800 FPM if the RPM was 2800. How is this possible? If the stroke is 6" and the RPM's are 2800 shouldn't I multiply those two numbers??
I am trying to go by your previous post to figure out what the calculation for piston speed is.
BTW, from the pilots manual of the F4U-1 PW-R2800-8W B series.
Combat RPM 2700
Military RPM 2700
Normal (max continuous) RPM 2550
Max cruise RPM 2150
Thanks
F4UDOA
Here's what it looks like:
(2,800 X 6)/6 = 2800. The 6's cancel out because you multiply and divide by 6.
Looking at the 109 again:
(2,700 X 6.3)/6 = 2835.
Just a coincidence the R2800 has a 6in stroke so the rpm will always be the piston speed in ft/min. Notice that the max continuous is kept almost right at 2500 ft/min for the R2800. It was a common rule of thumb in the engineering world at the time to limit the piston speed to 2500 ft/min. It was the same for automobile engines too. It was a limitation base mostly on the materials they were using for the connecting rod and crank which was generally cast iron. Cast iron is brittle and wont stand for a lot of cyclic loading. Modern castings are much more flexible and will handle 3500 ft/min easy. There were other things as I have mentioned that were also limiting factors to the rpm but the connecting rod and crank were the biggest. The figure of 2500ft/min and 3500ft/min are for continuous use. The casting technics and design and type of cast iron used are better today. For a forged steel crank and rods your piston speeds can be as high (continuous) as 4,000 ft/min. A really all out racing engines can hit piston speeds as high as 6,000 ft/min for a few seconds. Even those R2800 could have run piston speeds of 3500 ft/min for a few seconds I imagine.
Here's a comparison to a car engine:
Chevy 350cid - Stroke = 3.48 in
3.48 X 4,800/6 = 2,784 ft/min. 4,800 rpm was a conservative redline that was common on most Chevy's that reflected the peek horse power and hydraulic valves more than the engines ability to rev. The Z28 350 had a redline of 5,200 rpm which gives:
3.48 X 5,200/6 = 3016 ft/min. That's is for continuos use. That means you can get in your 74' Z28 and run it at 5,200 rpm all day long. I can vouch for a least 1 hour at 4,800-5,500 rpm in a stock 1979 Z28. The valves did start to float at 5,500 rpm. So I think those figures are correct. Of course you better have fresh oil and coolant, no leaks, etc. before you can do that. That's still conservative. Work backward from 3,500 ft/min:
3,500 = 3.48 X RPM/6, RPM = 6,034 rpm. That is the actual continuos use rpm of a 350 Chevy. I don't think your average factory engine with hydraulic lifters would do that all day long. I think with HIGH quality control and solid valve lifters the design would handle it. The limiting factor as I said above can reflect other things like the lifters. Hydraulic lifters tend to pump up and float the valves at high rpm. Now for an all out road racing 350 for a 24 hour race with solid or roller lifters:
4,000 = 3.48 X RPM/6, RPM = 6,890 rpm. That's not uncommon at all for a long distance racing engine to run that all day long. As a matter of fact that's a bit conservative.
An ALL OUT drag engine with roller lifters and aluminum rods:
6,000 = 3.48 X RPM/6 = 10,344 rpm! And you guessed it, that is a bit conservative too. That's not for continuous use though. That's a sprint for 5 seconds down the strip.
PS If you didn't already know what valve float is it's when the lifter that rides on the cam is thrown off the face of the cam holding the valve open into the combustion cycle causing back fire and even valve to piston contact. At high rpm the inertia of the valve train will throw the valve lifter off the cam. Stock automotive engines generally have hydraulic valve lifters that cause the effect to occur at lower rpm's. Hydraulic valve lifters are designed to take up the clearance in the valve train using the engines oil pressure. As the rpm's increase the hydraulic lifters over fill with oil and lift the valve off the seat. Racing engines run solid lifters that require periodic adjustment. Some stock engine are this way. Usually they are in older cars. Anyone that has had a old VW can tell you about adjusting valves. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif) Any way, high performance engines run solid lifters or solid/roller tipped lifters normally. They also run very high valve spring pressure to keep the lifter from flying off the cam at high rpm.
[This message has been edited by Jimdandy (edited 02-08-2001).]
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Dude,
You are full of good information.
Every once in while someone post something really bright and informative. I usually save the post as a text file in my documents collection. Usually it's Wells, Andy Bush or Badboy. I certainly will save this one. It fills in a lot of gaps for me.
I always wondered why more PW-R2800 aren't used at Reno and tuned for higher HP. The RR engines are putting out 4,000HP these days so I figured a PW should be able to do at least as much. It seems to me that they would have to rebuild one from scratch if it were to be raced all out. Very expensive I guess.
Has the liquid cooled technology surpassed the Air cooled by that much? Is anybody still doing research into improving large displacement Air cooled engines? I'd like to see what a R2800 could do if it were built completely of forged parts. Why is it so easy to modify a liquid cooled RR anyway?? They seem more fragile to begin with.
Thanks
F4UDOA
[This message has been edited by F4UDOA (edited 02-08-2001).]
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Originally posted by F4UDOA:
Dude,
You are full of good information...
Thanks
F4UDOA
Your welcome. I can see that one of the advantages of getting older and doing the different things I've done is acquiring a lot of varied information. I got a lot more engine info if you ever need it and I know LOT'S of motor heads. I was a diesel mechanic and went on to get my BS in Mechanical Engineering. Hot rods and engines are my 1st love. Planes are second and steam locomotives hold a strange sacred spot in my hart. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif) I didn't want to beat you up with a to much stuff. I hope I didn't bore you to much. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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Solid roller lifters make a big difference for the V8's. Even still, the first point of failure in most high performance V8's in terms of high RPM is the valve train.
Back when I was racing an oval track pro-stock, we had a V8 with solid roller lifters and a pretty high-tech valve train. We ran it at 7,200 RPM. And that was run for hours per race, 100-300 laps of a 1/4-1/2 mile ovals. We'd re-build it once about 1/2 way through the year, but that's it.
Most of the race engines that "throw a rod", do so when the valve train fails and drops a lifter onto a piston. It was pretty rare to see one go from bearing failure, and that was normally from oiling system problems or poor assembly conditions.
Forumula 1 engines are up to like 14 or 16 THOUSAND RPM. Wow. I don't even thing some of those use a "cam shaft". I think they are using electronic valve trains in them. Scary!
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Lephturn - Aces High Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com (http://www.flyingpigs.com)
Check out Lephturn's Aerodrome! (http://users.andara.com/~sconrad/)
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Originally posted by Lephturn:
...Even still, the first point of failure in most high performance V8's in terms of high RPM is the valve train...
Yes your right. The piston speed formula is actually a rule of thumb and not an engineering law. It really takes into account a lot of things. It's an easy way to explain a basic limitation of engine rpm without going to deep into valve train dynamics. It's like saying that if I get a steel crank and rods and the valve train to match I can turn 10,000rpm but with a cast crank and rods I can have the best valve train in the world and never turn more than 6,000rpm. As a I said above in the end the biggest reason you don't see Pontiac (50's-70's) engines out there tearing up the track like Chevy's is a weak valve train. Actually a weak block in the lifter galley area. You can over come the oiling problems in the Pontiac's but the block design limits you in the end unless you get an SD455. So the block design can also be a big factor. When you buy a races prepped short block there is a lot of over building already in it. It was all of the mistakes of the past that got it there. So all you have to worry about as a racer is how much money do you have to make power with this block. That is directly related to the cam and valve train and cylinder heads. Of course if your doing all your own machine work you have to look at everything.
[This message has been edited by Jimdandy (edited 02-08-2001).]
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As for LW a/c which could use MW-50 water-methanol injection such as the 109G-6 & G-10 (just 2 mention 2 109's) & the Fw 190A-5 & A-8 (just 2 name 2), a maximum period of 10 mins of boost could be used at any one time, and a period of 5 mins had to elapse before boost could be applied again.Generally, MW-50 tank sizes allowd for up to 30-40mins (I have differing accounts)of boost.That's 3-4 periods of 10mins each with a minimum of 5 mins between .
Jochen, I understand that a large number of 190A-8's used their EXT tank for MW-50 instead of avgas.The oft-quoted A-8 max TAS of 408 mph takes into account MW-50 boost.Having looked at the AH performance chart for the A-8, it is obvious that EXT is used for fuel only (if I fly the 190 it is normally the A-5, so I had not even noticed).
One of the main differences between the A-7 & A-8 was the rear fuselage tank that could be used for either fuel or MW-50, and the snall disparity in max TAS between the 2 is based purely on the A-8 using MW-50.Without MW-50, there would be almost no difference between the 2.
Should AH's 190A-8 be modelled with the EXT tank using MW-50 instead of fuel?I think we should be given the choice.A significant number of A-8's used the EXT tank for MW-50.I have read different opinions from different historians, but when you consider that most A-8's used an external drop-tank, and that the EXT tank was relatively small, it makes sense that many units would have preferred to use it for MW-50 rather than avgas.
After all, the bloated A-8 often needed as much of a performance boost as possible, and as most A-8's carried a DT, what makes more sense - using the EXT tank for a small amount of extra fuel, or use MW-50 to get a performance boost? If the rear tank is already there and is going to be used, there is an equal weight penalty in using either fuel or MW-50 in the EXT tank.
That being the case, I think we should have the hangar option of using fuel or MW-50 in the A-8's EXT tank.As for the A-5, I understand both the A-4 & A-5 both used MW-50 exclusively in their rear tank.
For those who don't know how MW-50 worked, here is an explanation of how it worked in the 109 models from the G-6 to the K-4.This info can be also used when referring to the Fw 190 :
The water-methanol mixture was injected into the supercharger below the powerplant's rated altitude, acting as an anti-detonant. Boost pressure from the supercharger was utilised to apply pressure to the 25 Imp. Gal MW-50 tank, forcing the mixture along a small pipe to an injection nozzle in the eye of the supercharger.The flow of MW-50 mixture was controlled by a solenoid valve activated by an automatic throttle switch & a master switch in the cockpit, and a 4% increase in power could be obtained, even at constant boost pressure.In the DB605AM powerplant used in the G-6 & G-14, fuel was consumed at 106 Imp. gal. per hour at take-off , but when using MW-50 with higher boost pressure , fuel consumption climbed to 141 Imp. gal. per hour. So extended use of MW-50 reduced range considerably, as well as having disastrous effects on the engine's spark-plugs, but this was generally regarded as a relatively small price to pay in return for increased performance - in the G-6's & G-14's using the DB 605AM, MW-50 boosted take-off power from 1,475 hp to 1,800 hp.
As a final note, the RLM realised that MW-50 boosting was not as efficient as improved supercharging (though improved supercharging AND MW-50 could be most beneficial), and as a result, emphasis was put on building a DB 605 powerplant with increased supercharging, which resulted in the DB 605AS engine being produced which was essentially a DB 605A using the DB 603's larger supercharger.The DB 605D was, to be simplistic, an enhanced version of the DB 605AS, utilising the same larger blower from the DB 603 with some ofther enhancements.
[This message has been edited by C_R_Caldwell (edited 02-09-2001).]
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Worth noting is that we have very reduced range in the MA, and the wep thingy might be a gameplay issue.
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Baron Claus "StSanta" Von Ribbentroppen
9./JG 54 "Grünherz"
"If you're not living on the edge, you're taking up space"
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Good info C_R_Caldwell thx.
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F4U, I would imagine one reason you do not see too many hot rod radial engine planes at reno with a R-2800 is cause they seem to put R-3350 or R-4360s in them. I do not know very much about this race plane stuff, but as a general rule, bigger is usually better.
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Ab Baureihe A-8 kann hinter Spant 8 entweder ein GM-1-Behaelter (85 Liter Inhalt) oder ein Zusatzkraftstoffbehaelter (115 Liter Inhalt) eingebaut werden.
Which means in english something like?
I think it says that either 85 l of GM 1 could be stored or 115 l of MW 50 boost liquid (or fuel)
Since the volumes are different it means that GM 1 stuff was not stored in ordinary MW 50 or fuel tank.
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jochen Gefechtsverband Kowalewski
Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.
Sieg oder bolsevismus!
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Right Jochen ;=)
danish
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As stated above the reason they limit the WEP bursts to an average of 5 minute intervals on these planes is the engine design. The inability for the internal parts of the engine to stand the higher cyclic loading for long periods of time. I don't know what they did to prep the rods in these engines. I'm guessing that they didn't polish and shot peen these rods in them because of the demands of mass production. There are a number of things that could be done to the internal components of these engines to increase there WEP times that just may not have been practical in mass production. Billet crankshafts, billet blocks, heads, rods, pistons. Sodium cooled valves, compression holes drilled from the top of the piston into the back of the compression ring groove to increase the seal of the compression ring. All of those things and more. All of those things would add a lot of machining time and material cost to the engines. They may have used some of the things I listed above on some of these engines. Generally the parts were castings and forgings I imagine with the least prep time passable.
PS I forgot a very important thing that limited the rpm ranges along with the materials used for the crank and rods. Back then they didn't have computer controlled machine tools so making a cam profile that was capable of supporting high rpm use was very hard. The acceleration and deceleration ramps and clearance ramps weren't as well profiled on those cams. For example if you were making a 1967 427cid ZL-1 Corvette engine today you would probably be able to get 30 more horse power out of the engine and have it be more "streetable" than the 1967 engine just do to better cam profiling because of computerized manufacturing.
[This message has been edited by Jimdandy (edited 02-12-2001).]