Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Crumpp on October 12, 2004, 08:48:57 PM
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Anybody know the nuts and bolts of exactly how a high Max CL affects performance. I know Max CL determines the envelope edge so I assume a high Max CL will mean good high-speed maneuverability and ability to carry a heavier useful load.
Any comments or anything to add?
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I know it effects instantanious turn performance although it is not the only factor. Wingloading is the other half of that equation I believe.
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Thanks F4UDOA.
I got a report from Focke-Wulf Bremen and it list's the FW-190 Max CL.
It's title is "Drag Data for Aircraft" and lists not only the Drag Polars but all kinds of aeronautical data. Even has the prop efficiency calculations for all the props mounted on the FW-190.
Right now the FW-190's high speed manuverability is primarily a function of it's drag in AH. Doing drag calculations based on the data in this document the FW-190 has less drag throughout a very large portion of the flight envelope than the Spitfire Mk IX.
I suspect the FW-190's high speed manuverability was more of a function of it's Max CL.
Crumpp
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CL=Coefficiency of lift, right?
I have somewhere a big thick book about the principles of flight. I'll take a dip into it and post if I find something useful.
Regards.
Angus
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Crummp,
What does it list as the clmax? Does it list stall speeds power on/off?
Sounds like some great stuff. Any chance of scanning and posting the doc?
Also does it have a flight envelope chart or EM diagram? I have never seen one for the 190.
Sorry about all the questions, sounds like good stuff.
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Sounds like some great stuff. Any chance of scanning and posting the doc?
It turned out to be a very hard document to get my hands on and it cost me a nice chunk of change. Not so sure I just want to give it out just yet. You can bet it will be in my book.
I did send Pyro a copy of the data sheet but I think he might need some help translating some of it. I had native German speakers pulling their hair out with some of the terminology and notations.
I will promise you F4UDOA, you will get a copy of it to post on your sight. You have shared way too much data not to get one.
Hope you understand. BTW I will be making some trips to various archives if I come across any interesting Corsair data I will grab it for you.
Also does it have a flight envelope chart or EM diagram?
No but it does have all the information needed to construct one.
CL=Coefficiency of lift, right?
Yes. The Max CL represents the maximum amount of lift a wing can produce AFAIK.
Anybody know the Max CL for the Spitfire, P51, 109, or other A/C to compare?
Crumpp
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I will promise you F4UDOA, you will get a copy of it to post on your sight. You have shared way too much data not to get one.
Hope you understand. BTW I will be making some trips to various archives if I come across any interesting Corsair data I will grab it for you.
Outstanding!!
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Originally posted by Crumpp
It turned out to be a very hard document to get my hands on and it cost me a nice chunk of change.
Crumpp
Who sells this data? Somehow I imagined these types of war records would be part of some government archive..
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Ok, I'm far from an expert and I'm greatly simplfying things to laymans terms, so true aeronautical engineers please correct me.
CLmax as was said is the maximum lift coefficent. Typically the higher the CLmax, the more lift your wing produces (per area) and the the higher the maximum angle of attack (AoA) you can pull in a manuever (lets call it a turn). I *think* its more applicable to sustained manuevers, not instantaneous.
So generally, if two planes have the same sized wing and the same wingloading, the one with the higher CLmax would be more manueverable. But nothing is without cost.
In general, to get a wing with a higher CLmax, you must have a thicker wing. Which means you have more drag, and a lower speed (all other things held equal).
This is all very simplified, but you get the idea.
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Thanks Vermillion!
I thought it had something to do with turning ability.
I understand the Spitfire Mk IX had a MAX CL of 1.3. Can anyone confirm this?
Crumpp
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I understand you are completely biased to 190's, and thus a book you write about them will not be an accurate resource to quote or base opinions on. Its like that isigrim guy writing a book on 109's.
Just from what i have seen, i wish you the best of luck writing it though.
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I understand you are completely biased to 190's, and thus a book you write about them will not be an accurate resource to quote or base opinions on. Its like that isigrim guy writing a book on 109's.
You don't even know me Furball. How can you say I am biased?
Crumpp
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I have read what you have posted on here before, and it seems to me that you are that way. Seems you are almost selective in the information you give out to highlight your point.
I often read the more technical posts, i find it fascinating reading about how the real aircraft performed, even though i am unable to comment or really add to the posts myself.
as i said: -
Originally posted by Furball
Just from what i have seen, i wish you the best of luck writing it though.
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the way I understand it,
the CL_{max} is the maximum lift coeff, obtained when the wing is at the critical AoA. Actually, this is how you define the stall angle.
as said above, this only sets the lift per surface area of the wing - I'm sure you know the formula. Having higher CL_{max} will allow using smaller wing for the same lift produced. The number usually quoted for it is the weighted average for the entire wing so you can just multiply (use the entire-wing lift formula) instead of integrating, when it's a non-uniform wing.
In terms of preformance, this sets the maximum lift (F) of the wing at a given speed and therefor the maximum attainable G load: G=F/m
Higher CL_{max} can be achived by wing profile design or by means of obtaining higher critical AoA - it does not nececerily mean a thicker wing, but it does 'usually' mean a dragier wing (per area).
Bozon
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CL max is multi functional, and tops out at a given speed for a certain design as far as I can see.
My bedtime book for tonight will be a book a got from a pilot friend of mine, "Principles of flight"
I will be back with some simple lines tomorrow.
Regards
Angus
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I have read what you have posted on here before, and it seems to me that you are that way. Seems you are almost selective in the information you give out to highlight your point.
That is extremely general and frankly It's quite tough to dispute your opinion based on your assumptions. There are no real facts or specifics to dispute. Oh well sorry you feel that way.
Let me explain some things:
1. I have set some fires in motion (unintentionally) for sure. Some really good data did comes out. I am always polite but not the most internet savy guy. It has amazed me the number of things people take out of context or attach emotions too, which frankly, simply are not there.
2. I will question when I don't think it's right.
Thank you Bozon for the explaination. How does a high Max CL benefit a fighter?
Looking forward to your graphs Angus.
Crumpp
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Keep up the good work Crumpp! :aok
-C+
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Thank you Bozon for the explaination. How does a high Max CL benefit a fighter?
max CL by it self doesn't mean much. What matters more is how much lift can the wing generate at the given speed. This will set the maximum G that can be pulled (if not capped by structure of pilot limitations). This means instantanious rate of turn.
What matters is the entire wing, not just CL. Perhaps the thing to compare between planes is not wing-loading but "max lift-loading": CL*S/m ?
Bozon
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Crummp,
I think the answer to your question is yes.
However high Clmax is more of a byproduct of performance than a cause or indicator.
Example all my numbers are from the P-38 flight manual BTW.
The P-38L has extremely high wingloading. 17,000lbs/327sqft=52
However at 17,000lbs it stalls power off at 100mph in the clean condition.
It has a high Clmax which can be calculated this way.
Weight * 391=> airdensity at sea level / Speed ^2 * Wing area
or
17,000lbs * 391 / 100MPH^2 * 327Sqft
6647000 / 3270000
= CLmax =2.03 <==That is really high!
The long wingspan and high aspect ratio increase the Clmax while keeping Cdi(induced drag) low therebye reducing stall speed.
The P-38 does have an odd distinction of having a higher stall power on than off. This has been explained to me as a byproduct of the prop rotation but I do not unstand it enough to explain it.
If you know the FW190's stall speed (power off) you can calculate the Clmax very easily plugging in the speed, weight and wing area.
Most WW2 fighters are between 1.4 and 1.6.
Your number of 1.3 for the 190 is probably from wind tunnel test with no propellor installed. The F4U Clmax with no prop is 1.28 approx but increases to 1.49 with the prop idling.
Also a good trick to come up with 3G, 4G etc stall speeds is to multiply the 1G stall speed by the square of the G force.
For instance if the 1G stall is 100MPHthen to get the 3G stall speed multply the square route of 3 which is 1.73 by 100MPH and you get 173MPH 3Gstall. This is a rough number but you get the idea. This is why stall speeds are so important and why Clmax is important. This is only instanious turning. Sustained is more a function of thrust to weight.
Now remember Clmax remains the same regardless of weight. So if the P-38 weight is reduced then the stall speed is also reduced but the Clmax is constant.
So you can take that Clmax calculation and figure out the stall at any given weight. From there you can figure out the 3G stall at any given weight and then make your own EM diagram.
Of course remember I have learned these calculations on these and other boards so my numbers are very primitive compared to what HTC is doing.
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My bad on the P-38 Clmax. I didn't check the CAS chart.
If the P-38 is indicating 106MPH you are really flying at 120MPH so there is a minimum 14MPH adjustment. It gets worse as you go slower.
So try this
17,000MPH * 391 / 114MPH^2 * 327sqft
6647000 / 4249692
Clmax = 1.56
That is more in line with everyone else.
Note: Always check airspeed indicator error IE. CAS chart
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So the P38's is 1.56
The Spitfires is 1.3
Max CL has to be combined with wingload
Your number of 1.3 for the 190 is probably from wind tunnel test with no propellor installed. The F4U Clmax with no prop is 1.28 approx but increases to 1.49 with the prop idling.
The 1.3 is the Spitfires. The NACA tested it and found a Max CL of 1.1. The RAE tested it and found 1.3, AFAIK.
What matters is the entire wing, not just CL. Perhaps the thing to compare between planes is not wing-loading but "max lift-loading": CL*S/m ?
Thanks Bozon. Was it you who was doing the EM diagrams for some of the fighters?
Crumpp
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sorry crumpp, but no. I'm no aeronotics engineer so such stuff will be too much of an effort for lazy me...
btw, I wrote the lift load upside down, should have been m/(maxCl*S).
Bozon
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What book and when? I am a new member and this is my first time to drop in this forum so please enlighten me!
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Do you have a source for the higher power on stall speed of the P-38? I have a pilot manual for the plane and it does not mention this phenomenon. Do you have speed figs for power on stall speeds? Is the effect similar clean vs. landing condition? Sounds honestly speaking a bit odd.
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Bozon,
What is the "M" stand for in your lift load equation?
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pasoleati,
My source of that data is a book which is actually the record of the 1944 Fighter Conferance held by the Navy. The Book/Transcript is called "Report of Joint Fighter Conferance" NAS Patuxent River MD 16-23 Oct 1944. It is easily found and purchased and full of information.
The stall speeds themselves I rely on the manuals for because the stalls in the book are in a range with no weight, condition or power listed. However the one thing that stands our about the P-38 stall is that it is higher power on than off. I though it was a misprint at first but a guy who used to be on these boards explained to me that it was really a function of the propwash on the P-38. The guy goes by "Wells". He is one of the creators of the online simms Target Korea and Target Rabaul.
In anycase get the book. It is one of the best sources of data I have found and lets you know what the actual fighters pilots thought in 1944.
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I have the book in my shelf. I really have to check the figures. I do agree that the book is essential reading for serious fanatics!
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[Since you are a Corsair man, do you have any info whether installing outerwing slats were considered for curing the bad stalling characteristics? BTW, Corwin Meyer made some interesting comments on the subject in his pilot report of the Corsair is Flight Journal´s F4U special issue!
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I have never been a fan of the outer wing slats such as the ones on the 109 or La-7. They seem to have caused more of a problem than anything else during combat maneuevers. The F4U had a spoiler on the starboard wing to give it more of a symetrical stall but it lowered the overall Clmax of the A/C. This fix was implemented after the first 800 F4U's built and continued throughout the production so apparently it was deemed a sucess by Vought.
The stall of the F4U is somewhat subjective. It was harsh for a Navy A/C of the time but when compared to it land based contemporaries it was considered gentle in that respect.
Corkey Meyer has been writing the same artical for 20 years. It is just a shame that Boone Guyton is no longer around to give the Vought perspective. Some of his points are very valid. He doesn't really get into performance comparisons very much. Just where Vought could have done better. I would luv to talk to that guy about the F6F and F4U.
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Originally posted by Furball
I understand you are completely biased to 190's, and thus a book you write about them will not be an accurate resource to quote or base opinions on. Its like that isigrim guy writing a book on 109's.
You`d be surprised.
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Surprized?
Naaaaa :D
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Well, the problems caused by slats seem to be overrated. As far as the 109 goes, the Finnish AF test report has no mention of any difficulties caused by slats. As for the La-7, Eric Brown who is one often quoted source for that slat problem in the 109 flew also an La-7, yet found no adverse effects caused by slats. And I have never read that the slats were any problem in the SB2C. And no one has ever complained about Me 262´s slats.
Though many land based a/c had bad accelerated stall, in landing condition the Corsair seems to be the worst of major American fighters. This I conclude from Dean´s book.
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m is mass.
I was suggesting that comparing the wing load - mass over wing area (m/S) may be less meanningful than (m/(S*CL)).
The logic is that if you slap two barn doors to a plane, they are going to be less effective than two proper wings of the same area.
If you want even better, you can use effective area, instead of real area.
Bozon
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Bozon,
What is the benifit of Lift loading compared to span loading? Is that the same thing?
pasoleati,
Most of the information I have read on the problems with slats have been accounts of 109's having them open at bad times during dogfights causing them momentarily loose control (for lack of a better term) in a dogfight. Clearly the technology existed at the time but the Germans and the Russians seemed to prefer them on their fighters where the Brits and Americans did not.
As far as the F4U stall when compared to the P-51D, F6F-5 and P-47D by a Modern group of military test pilots in 1989 the F4U stall was described as having "adaquate stall warning and docile behaivior at the stall". The worst of the bunch was the P-51D. Indeed the F4U had a bad stall by 1943 carrier standards but it also had the best performance.
AHT numbers to a large degree are based on the numbers from the Fighter conferance. Especially the stall data. Mr.Dean is the guy who was responsable for having that report published.
I wish I had the Elgin AFB reports as well. Some of the Elgin report is in Boone Guytons book.
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Hi F4UDOA,
>I have never been a fan of the outer wing slats such as the ones on the 109 or La-7. They seem to have caused more of a problem than anything else during combat maneuevers.
Actually, the disadvantages have been painted larger than life by a number of books.
Originally, the Me 109's slats were designed to be locked while the flaps were retracted, and to be released at about 10° flap deflection. They wouldn't have "interfered" with combat flight at all. In 1936, Messerschmitt conducted an extensive (and, at 2 million Reichsmark, epensive :-) series of test flights for evaluating the effects of free slats, and found them to be favourable through the entire flight envelope. As a result of these tests, the locking mechanism was deleted from the Messerschmitt's slats.
>It was harsh for a Navy A/C of the time but when compared to it land based contemporaries it was considered gentle in that respect.
Well, the land based aircraft didn't have to be put down on a boat, so that's double-edged praise ;-)
Regards,
Henning (HoHun)
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m is mass.
I was suggesting that comparing the wing load - mass over wing area (m/S) may be less meanningful than (m/(S*CL)).
The logic is that if you slap two barn doors to a plane, they are going to be less effective than two proper wings of the same area.
If you want even better, you can use effective area, instead of real area.
Interesting. Might do up a little excel spread sheet to compare different planes.
Crumpp
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Many experienced 109 Pilots (Such as Rall) did not favour the Slats. Reason: They could clonk out and affect balance shortly during delicate moments, such as setting the enemy up for a shot.
British test pilots did not particularly favour them (flying captured 109's) except in the landing procedure.
I belive that some expert pilots though, such as Marseille, did learn the slats to the end, and benefit for it.
All a question of choice.
BTW, some LW pilots are told to have their slats fixed as shut.
(field mod)
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Many experienced 109 Pilots (Such as Rall) did not favour the Slats.
True.
I have also heard from several 109 pilots that "The real manuvering did not begin until the slats deployed".
Crumpp
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Hi Angus,
>Many experienced 109 Pilots (Such as Rall) did not favour the Slats. Reason: They could clonk out and affect balance shortly during delicate moments, such as setting the enemy up for a shot.
Well, where's Rall's quote? Who are the "many"? Not that I don't believe you, but I've seen books printing generalizations where they shouldn't have, and I guess this particular Rall quote might be just one URL away :-)
I've not yet found a believable explanation why the slats should negatively "affect balance" at any time.
In a gunnery pass, they could deploy when you tighten up your turn, but that's one bang, and that was it.
Any "delicate" gunnery pass would have to take place at a fairly constant Cl, there'd be one transition at best, either slats going out or slats retracting.
Regards,
Henning (HoHun)
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Rall's quote is actually from a TV inteview. A friend of mine has that on a VHS.
I must confess, I sometimes throw out some strings from memory only, but only when I am fairly safe it is correct.
Now, since I met Rall and spent a day with him, there may have been something he said there also. Anyway, there is something sitting in the back of my head as this:
"The slots would not always deploy equally, thus yawing the aircraft for a moment, that was quite strong enough to throw you off your gunsight"
(My wording)
Anyway, I will check out and see what I can find out more.
Might be some days though.
BTW, the basic slats on the 109 were a British design, - Handley-Page
(Again from memory)
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"The slots would not always deploy equally, thus yawing the aircraft for a moment, that was quite strong enough to throw you off your gunsight"
I have heard that as well. I understood though, it only occurred in an uncoordinated turn.
Crumpp
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Hi Angus,
>I must confess, I sometimes throw out some strings from memory only, but only when I am fairly safe it is correct.
I actually think you're correct, since I seem to remember something like that as well :-) Still, it would be nice to have the actual quote.
Here are a couple of quotes regarding slats:
http://www.virtualpilots.fi/hist/109myths/#slats
>BTW, the basic slats on the 109 were a British design, - Handley-Page
>(Again from memory)
Correct again :-)
They were invented at Handley-Page by the German engineer Gustav Lachmann who held a patent for slatted wings in Germany, which had been the reason for his recruitement. Lachmann actually stayed with Handley-Page, who were closely cooperating with Messerschmitt during the test flights I mentioned. (Lachmann seems to have been an aircraft designer with Handley-Page at that time - I've seen him mentioned as creator of the Handley-Page Hampden.)
Regards,
Henning (HoHun)
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The HP patent dates from WWI or just after. A German engineer came up with the same idea at about the same time and obtained a patent in Germany. The two cross licensed and these slats were quite popular on European designs in the early 1920s.
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Originally posted by HoHun
Hi Angus,
>BTW, the basic slats on the 109 were a British design, - Handley-Page
Henning (HoHun)
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Originally posted by F4UDOA
Most of the information I have read on the problems with slats have been accounts of 109's having them open at bad times during dogfights causing them momentarily loose control (for lack of a better term) in a dogfight. Clearly the technology existed at the time but the Germans and the Russians seemed to prefer them on their fighters where the Brits and Americans did not.
Most of such information is based on the single RAE report on that 109E the french had captured after it belly landed, had a bent fusalage, and then passed over to the Brits who seen the thing for the first time and didn`t like the slats they never seen before on the fighters they trained with. I don`t know if they had trouble with the particular, damaged and badly maintained aircraft, but it can`t be ruled out.
What is appearant though, that the same problems was not felt on the 109G, which would mean it`d be hardly a problem on the similiar F and K:
"One interesting feature is the leading edge slats. When these deploy at low speeds or in a turn, a 'clunk' can be heard and felt, but there is no disturbance to the aircraft about any axis. I understand that the Bf109E rolled violently as the slats deployed, and I am curious to know the difference to the Gustav that caused this."
Besides, the slats open only if one of the wings begin to stall. On an aircraft with no slats, when this happens the wing will drop and the firing solution is gone to hell; on aircraft with slats the slats will open, restore the airflow over the wing, and instead of a violent roll, there may be some disturbance - or no disturbance at all, as the qoute shows. Another good thing about slats is that they enable the pilot to fire very high deflection shots - normal wings simply can`t support so high AoA that is required for those !
As for why the Soviet/German designs employed it, and US/UK ones not, it`s fairly simple, all the latter relied on wing mounted guns, not having an fighter engine I can think of that would enable them to mount fuselage weapons, being normal Vee ones, with rear mounted compressors.. and so the wing guns took the space away in the leading edge required for slats. And BTW, if the slats would be bad, they wouldn`t be on 95% of the modern Mach 2 jet fighters today...
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Ooff, from memory again.
The slats sometimes had the habit of opening up when hit by rough at high speed. (On the 6 of an enemy plane it was often a tad rough)
The high deflection shots are worth looking into, - most kills were made at very low deflection.
Now, a pilot who definately benefitted from the slats to get him into a good position was Marseille, - while one of the finest deflection shooter of them all, Rall, did not prefer the slats in combat.
Todays fighter jet slats are deployed how?
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Well, IMHO it seems that would have been enough span left outboard the wing guns to fit slats.
F4UDOA, could you perhaps supply me a copy of the entire SETP eval report of those 4 fighters? I have seen quotes of it, but not the entire one.
If you can, contact me at paso.leati@@reppu.net (del one @)
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Originally posted by pasoleati
Well, IMHO it seems that would have been enough span left outboard the wing guns to fit slats.
Do you mean like this?
(http://dspace.dial.pipex.com/town/avenue/vy75/planes/la-5.gif)
The early P-51s had cowl mounted mgs.
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The slats sometimes had the habit of opening up when hit by rough at high speed.
Interesting. Made me think of the propwash thread.
Crumpp
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Originally posted by Angus
Ooff, from memory again.
The slats sometimes had the habit of opening up when hit by rough at high speed. (On the 6 of an enemy plane it was often a tad rough).
[/B]
IIRC Eric Brown commented this. But then again, propwash that caused it throws around any plane a bit, so again not really related to the installation of slats.
The high deflection shots are worth looking into, - most kills were made at very low deflection.).
[/B]
Most fighters didnt have slats in WW2. ,)
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Well, Izzy? (I rather suspect so), Some of the most common fighters of WW2 (109, lala) Did have slats.
Some of the 109''s pilots chose to shut those though.
In AH, they work marvelously, if it is a good representation of the real life, I'd like them.
BTW, they don't seem to be so common on light aircraft today. Why comes? Too expensive?
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Well, it is indeed due to costs that these lightplanes are simple blasphemy to real enthusiasts!
BTW, it might be worth adding that Frederick Handley-Page (or the company, don´t recall) got some aviation safety prize for these slats before the war. This was mentioned in Putnam´s marvellous "Handly-Page Aircraft" book.
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Hi Angus,
>The slats sometimes had the habit of opening up when hit by rough at high speed. (On the 6 of an enemy plane it was often a tad rough)
For all planes, slats or not :-)
In fact, if it became really rough, the slats were beneficial because they could prevent flick stalls. Douglas Bader during the Battle of Britain once climbed up to the six of a Heinkel bomber he was trying to intercept - only to spin out immediately when the wake hit him. Asymmetrically deploying slats would have prevented the spin, even if the fighter might have been thrown around.
>Todays fighter jet slats are deployed how?
I believe slats have been mostly replaced by drooping leading edges from the F-16 on. However, Handley-Page slats were used on the Me 262, F-86, A-4 and F-4 (for example), so they remained principally unchanged for decades.
I'd speculate that the change to different principles (if I'm right there, I'm no jet expert) might be connected to the introduction of computerized flight controls systems with the F-16 generation of, jets where a higher degree of control by the FCS might have been desirable.
Regards,
Henning (HoHun)
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Hi Angus,
>BTW, they don't seem to be so common on light aircraft today. Why comes? Too expensive?
Roger that. Moving parts, always a major cost driver.
It's often said that the 1930s' Bf 108 is still technologically on par with the typical Cessnas, Pipers and Robins that are around today, but I suspect that if you compare prices, you'll find that the beautiful Bf 108 was several times as expensive then these :-)
Many aircraft are using fixed slats instead of the automatic ones, including some modern STOL aircraft.
Regards,
Henning (HoHun)
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I've seen a 108 flying actually.
A purring beauty ;)
Oh, this:
"Asymmetrically deploying slats would have prevented the spin, even if the fighter might have been thrown around. "
That was the problem I belive, at least on the 109.
The slats did not deploy that way. You could have one of them clonking in and out for instance, - i.e. in a turn.
One very beautiful aircraft is a WW2 era Dornier, just can't remember the model.
Well, it's a 6 person (or so) tail dragging upper wing aircraft, probably an army liasion plane or that sort of stuff.
It has a somewhat powerful engine I belive, and quite some wingspan (It's quite a bit bigger than a Cessna 172 for instance)
It has front mounted fixed slats.
The Stalling speed is 27 knots as far as I remember.
Very short takeoff roll as well.
I'll se if I can find a pic-link for it ;)
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Ahh,look here.
Nice one.
Resides in Iceland BTW.
(http://www.islandia.is/aeroweb/islenski_flugvefurinn/mulakot/pages/mul01_1493m-14_tflds_png.htm)
if link does not show picture, press here:
http://www.islandia.is/aeroweb/islenski_flugvefurinn/mulakot/pages/mul01_1493m-14_tflds_png.htm
Don't know why....
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Hi Angus,
>>"Asymmetrically deploying slats would have prevented the spin, even if the fighter might have been thrown around. "
>That was the problem I belive, at least on the 109.
That was not a problem, it was a solution :-) Asymmetrically deploying slats restored symmetrical lift. No slats, asymmetrical lift, you roll or flick.
>You could have one of them clonking in and out for instance, - i.e. in a turn.
At a certain Cl, they were either in or out. Pump the stick, and they come in and out. Stick pumping is not good for you aim anyway :-)
>One very beautiful aircraft is a WW2 era Dornier, just can't remember the model.
You had me puzzled with this one :-) It's actually a post-war aircraft, the first to see production in Germany after WW2.
Some of these are still flying, they are very good STOL aircraft indeed. The real jaw-dropper is the Storch, of course, it's not really flying but ridiculing gravity :-)
Regards,
Henning (HoHun)
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Originally posted by Angus
Well, Izzy? (I rather suspect so), Some of the most common fighters of WW2 (109, lala) Did have slats.
Hmm, what I can think of is the 109 (plus all other Mtts)and the Lavochkin 3/5/7 . Thats indeed a nice number produced, but still uncommon if you look at all fighters produced in WW2. Yaks, P-series, Spits/Hurris and so on.. cant think of a jap. fighter that had them neither. On the second though, Junkers liked the idea, too, using his own patented trailing edge slats.
Some of the 109''s pilots chose to shut those though.[/B]
I find that rather hard to believe, for one I havent seen any actual proof of that, its much more like an urban myth like many regarding the 109. I guess the only time a 109 had its slats locked was probably when they were damaged and there werent time to fix them before flight etc.
BTW, they don't seem to be so common on light aircraft today. Why comes? Too expensive? [/B]
Maybe. But then I think they are not neccesary. Ad1, light hobby aircraft have generous wing area and lift, and are usually shoulder-winged types (which comes with great stability). Plus slats only help at high AoA, ie. hard turns a fighter is likely to perform, but I doubt any sensible, or at least not insanily rich man would pull 6-7 Gs with a Cessna that isnt designed for such loads in the first place.
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Do any of the modern aerobatic a/c have slats?
Any WW2 era trainers have slats?
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Slats do help on slower aircraft and nicely at landing or slow speed handling. They were popular in the 30's.
As I have showed also, slats are good on "bushplanes" as well.
I think they were definately no kind of genious invention for high speed and high G maneuvers, bur rather as a stall-aid.
If German aces did not prefer those in combat (and I did see Rall say that actually, so there goes the urban myth), that would support that. I will find something more there, gimme a bit of time.
There are many allied planes that could have had them, after all, they were not a novelty.
A P38 with slats? Hurricane? Spitty, if you skip the outboard mg's.(some pilots had that done as field mod).
Didn't some jap planes have slats?
Anyway, why did the US go for the combat flap instead? And Japs?
Were they silly or what?
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Hi Angus,
>Slats do help on slower aircraft and nicely at landing or slow speed handling.
Messerschmitt shelled out 2 million Reichmarks to investigate whether he should keep the original locking mechanism that restricted the use of the slats to landing and slow flight, deciding that the way to go was to allow them free operation, and you wipe away this decision (based on countless test flights) with one push of a button? :-)
Don't try to deceive yourself, Angus. The Me 262, F-86 and F-4 are no slow "bushplanes", but a hell of a lot faster than the Me 109, and Handley-Page slats worked great for them.
>Were they silly or what?
The slats are an inherent part of the wing design, you don't just slap them on as an afterthought. The Spitfire for example didn't use slats, but relied on wing-twist (washout) to retain aileron control at high angles of attack. The Me 109 on the other hand had a "straight" wing, no washout at all, which is quite efficient but calls for some other device retain full aileron control at high angle-of-attack.
If they fit your design philosophy, the Handley-Page slats are excellent, but they don't fit it every case.
Regards,
Henning (HoHun)
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Scratching my head here:confused:
Ok, so Willy modded the original Handly Page mechanism so that the slats would deploy relevantly to stall condition at any speed, not just the slow speeds. Am I understanding right?
So, they still worked at slow speeds right, just no particular upper limit?
So,providing I understand you correctly, it comes to this:
"Don't try to deceive yourself, Angus. The Me 262, F-86 and F-4 are no slow "bushplanes", but a hell of a lot faster than the Me 109, and Handley-Page slats worked great for them. "
So you're saying that both the F86 and the F4 had the Messerchmitt mod rather than the original?
Eager to learn, always, and not immune to mistakes, so sorry if I misunderstand.:o
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AFAIK the slats open at a certain AOA, regardless the speed.
A couple of interesting links about the subject :)
http://109lair.hobbyvista.com/techref/systems/control/slats/slats.htm
http://simhq.com/_air/air_002b.html
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Hi Angus,
>Scratching my head here:confused:
Sorry, I guess that's my fault! I'll try to be more accurate now :-)
>Ok, so Willy modded the original Handly Page mechanism so that the slats would deploy relevantly to stall condition at any speed, not just the slow speeds. Am I understanding right?
The original mechanism were free-moving slats. The initial Me 109 design had an additional locking mechanism that did not allow the slats to come out of the wing unless 10° or more of flaps were deployed. This had nothing to do with the flap design, but it was old-fashioned mechanics.
(As I read about the SM79 having a similar mechanism, that might have been common practice then.)
In 1936, Messerschmitt considered the option of leaving the slats free throughout the entire flight envelope. That was apparently not common practice, at least not for high-performance planes, as intensive research was required. Gustav Lachmann of Handley-Page's contributed, obviously tackling the problem of high speed flight for the first time, too.
(Lachmann suggested a pneumatic emergency retraction for the slats in case they should induce an irrecoverable spin. Only during the trials it became clear that they actually made spins less likely and helped with recovery.)
>So, they still worked at slow speeds right, just no particular upper limit?
No, just no mechanical downlock anymore. The slats are not triggered by speed, even though it's often presented that way in books and on the internet. They are triggered by the airstream dependend on angle-of-attack (you could also say dependend on lift coefficient, because AOA and Cl are connected), so they'll come out at high speed in a high-G turn just the same as at slow speed in 1 G flight.
>So you're saying that both the F86 and the F4 had the Messerchmitt mod rather than the original?
Well, Messerschmitt didn't actually change the slats, he merely was the first (as it looks) to use them on a high-speed aircraft. As far as I know, the F-86 and the F-4 had the same type of slat as the Me 109, which basically was what Lachmann invented at Handley-Page in 1919.
>Eager to learn, always, and not immune to mistakes, so sorry if I misunderstand.:o
Probably I mis-explained :-) Sorry for that!
Regards,
Henning (HoHun)
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FYI, the first F4s did not have the slats and in Vietnam skies it was evident that F4 could not rely entirely on its missiles but had to "mix it" with enemy fighters. Violent high speed maneuvers tended to cause "departures" which were not always recoverable so computer controlled slats were installed. The top speed dropped though, but the effect on handling was considered so big that it became a default configuration in F4.
-C+
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Ok.
So what Willy did was to remove the flap-related mechanism (lock) and allow again the free movement of the slats.
My friend is on the hunt for Rall's slat quote, - he has it on video tape. I'll post it as soon as I get it.
Regards.
Angus