First Aircraft to Use a Symmetrical Airfoil

[Jane-DoH]

What were the first airplanes in the world ever to use a symmetrical airfoil cross-section?

[barit1]

Don't know the answer, but here's a starting place (http://www.public.iastate.edu/~akmitra/aero361/design_web/airfoil_usage.htm). :)

[bearfoil]

I am guessing. I would think that prior to the Wrights, early manufacturers would have used a flat surface as an airfoil. By definition symmetrical, but only due to lack of test or inspiration perhaps. Technically, Lilienthal employed flexible canvas wings?? Also technically symmetrical. The Rogallo comes to mind, I owned a Manta, it certainly was symmetrically airfoiled. For all his fame, Bernoulli predated all wings, his data was applied, and linked to fluid research.

The first Boomerang was perhaps flat, to be updated by a bright hunter in the outback

Some old guys may remember the 'Thermic50', or the junior 'Ringmaster' ?

bear

[PBL]

Looking through the list referenced by barit1, I would suggest:

Air-breathing Powered: Heinkel He 280, 1941 (flew unpowered 1940).

Jet-powered: Heinkel He 176, 1939.

Sailplane: Bowlus Senior Albatross, 1932.

Better info, anyone?

PBL

[barit1]

Not on the list, but Vultee's model 51 and derivatives (V.54, BT-13 (http://en.wikipedia.org/wiki/Vultee_BT-13_Valiant), BT-15 etc.) had a symmetrical airfoil - probably NACA 0015. The V.51 first flew in March 1939 per Wikipedia.

And (I'm speculating here) the earlier Vultee SE transports (V-1A (http://en.wikipedia.org/wiki/Vultee_V-1)...) likely also used the same airfoil.

EDIT: While the Vultees are not listed, the Universal Products XBT-16 shows a "NACA 0018-64 mod" root airfoil. Inasmuch as the XBT-16 was a BT-13 modified to use major components made of molded plywood vs aluminum, I'd expect the other Vultees used the same airfoil.

[diesel addict]

I an fairly sure the B-17 used NACA0015....

[ChristiaanJ]

I am guessing. I would think that prior to the Wrights, early manufacturers would have used a flat surface as an airfoil.Eksplain?
Airfoils well before the Wrights were already cambered... the whole notion of camber as against flat-plate was understood already.

What were the first airplanes in the world ever to use a symmetrical airfoil cross-section?Interesting question.... what made you ask it?
I'll have to pull out my textbooks (from 45 years back) to check, but my memory is that just about any asymmetric airfoil is more efficient, and that about the only use for symmetric airfoils was on aerobatic-type aircraft, that spent half their flying time upside-down anyway.
(BTW, Jane, my question is meant seriously, since this is TechLog, not JB.)

CJ

[barit1]

The B-17 started out as Boeing's model 299, and it used NACA 0018. Its commercial derivative, the 307, likewise.

Also using 0018, Boeing's much larger XB-15, as well as the flying boat 314 which borrowed the XB-15's wing. The XB-15 was probably the earliest of the lot.

[diesel addict]

B17 used NACA 0018 (Root) NACA 0010 (Tip) ergo NACA 0015 somewhere along the semi-span....

agreed about the XB-15.

[bearfoil]

ChristiaanJ

Of course there was camber before the Wright's, but I was trying to suggest symmetricals?? Canvas is an airfoil, and simply because its shape in flight is "cambered", so is its 'under panel', hence the symmetrical requirement for the question?? A solid plane doesn't warp or curve in flight, for purpose of discussion, so it is a flying symmetrical?? No? F-104? I have gazed down the hard points at the tip at the "S" curve. For purposes of discussion, even though it "curves" it is very close to "symmetrical" as it is so very thin in section. This opinion wants a little leeway. Do you still have that nifty pic of the wing??

bear

[Turbine D]

Jane-DoH

I have no idea for sure, but here is a clue:
Gehard Fieseler in the early 1930's in Germany.
Fieseler became a leading light in European aerobatics; the aerobatic judging system he devised was the first to use coefficients of difficulty and was adopted internationally. He became the highest-paid airshow pilot in Europe, which allowed him to buy a small glider factory at Kassel. One of the first aircraft he produced was his special aerobatic machine, the Tiger, which introduced the first symmetrical airfoil (or wing section), now an essential feature of aerobatic machines.
He later went on to start a business that built FW190's during the war.

Turbine D

[Brian Abraham]

Fieseler Tiger used the NACA M-12 aerofoil, which is not symmetrical, rather more like the Clark Y.

http://www.worldofkrauss.com/foils/draw/56.png?axes=true&chord=5

[Jane-DoH]

ChristiaanJ,

Interesting question.... what made you ask it?

Mostly it had to do with the P-51 Mustang, which if I recall, had a symmetrical airfoil. I was just wondering what the first plane to make use of a symmetrical foil was.

[Brian Abraham]

The P-51 used the NACA 45-100 which was supposed to be a laminar airfoil but never achieved that status due to manufacturing tolerances. Was not a symmetrical airfoil.

From a NASA report
One of the major emphases of the documentary record is the experience of the North American P-51 Mustang, one of history’s most remarkable airplanes and the first aircraft to employ a NACA laminar-flow airfoil. More than any other case study, the Mustang’s performance in the war demonstrates how the NACA’s laminar-flow airfoils proved to be a success, despite also being a failure. The record of this magnificent fighter plane confirmed expectations of appreciable improvements in speed and range as a result of the low-drag design, but practical experience with this and other aircraft using advanced NACA sections in the 1940s also showed that the airfoil did not perform as spectacularly in flight as in the laboratory. Manufacturing tolerances were off far enough, and maintenance of wing surfaces in the field were careless enough, that some significant points of aerodynamic similarity between the operational airfoil and the accurate, highly polished, and smooth test model were lost. Because the percentage drag effect of even minor wing surface roughness (e.g., dirt, dead bugs, and the dusty footprints of airplane crewmen) increased as airfoils became more efficient, laminar flow could be maintained in actual flight operation only in a very small region near the leading edge of the wing.

Still, the Mustang’s airfoil section turned into an excellent wing. Ironically, this development was due to its high-speed performance rather than its low-drag. In “one of those rare instances in the history of technology in which a system becomes a success because it unexpectedly excels at something for which it was not originally designed,” a decade of dedicated airfoil research by the NACA resulted, not in what Eastman Jacobs and his colleagues were after, but in something else, almost as good.27 Not only were the NACA’s 6-series laminar-flow airfoils used with great success on the Mustang, they were also to be employed on just about every other high-speed airplane that came after it, up to the time that sophisticated computer-aided design took over and started customizing advanced airfoil shapes in the 1980s.

[Jane-DoH]

Brian Abraham,

I assume the P-51's wing worked well because of it's transsonic characteristics (the crest moved far aft and so forth)?

[PBL]

I assume the P-51's wing worked well because of it's transsonic characteristics (the crest moved far aft and so forth)?

What do you mean by "crest"?

PBL

[bearfoil]

Yes, what is crest as relates to this wing?? A crest is otherwise known as a "ridge", danged if I can imagine a crest or ridge helping this wing behave.

PBL....I rather liked the wind tunnel example.

[barit1]

Jane-DoH uses the term "crest" I think to describe the point of maximum thickness of the airfoil. In the P-51's case the max is at 45% chord - unusually aft for that day, when most airfoils had max thickness at 25 or 30% chord. And there was a distinct inflection at the 45% point so the thickness decreased rapidly as the air flowed aft.

I've been searching for a profile drawing of the NACA 45-100 to illustrate this - not successfully so far.

[Jane-DoH]

PBL,

I meant the thickest part of the wing. I actually thought that area was formally called the crest...


barit,

In the P-51's case the max is at 45% chord - unusually aft for that day, when most airfoils had max thickness at 25 or 30% chord. And there was a distinct inflection at the 45% point so the thickness decreased rapidly as the air flowed aft.

So the only reason these characteristics were incorporated into the wing was to produce laminar flow, or were these characteristics also implemented to reduce wave drag?

[barit1]

Completely tangential to this technical conversation:

I find it most interesting that the NACA research on early laminar-flow airfoils
found its first implementation in an aircraft designed for the export market. The British were visiting US manufacturers, and as the story goes, they asked NAA to become a second source for the Curtiss Kittyhawk. NAA countered with their own design, the NA-73, incorporating US taxpayer-funded research, and won the British contract.

Glad it all worked out in the end, but did NAA or the British ever compensate the US government for that research? There are modern examples of US manufacturers doing so when government-funded projects are reborn in the civil market (GE paid a royalty on CF6's for their TF39-based content, for example).

(Maybe this is Jet Blast material...)

[bearfoil]

barit1

Interesting point. The P-51 was initially supplied to the British as the APACHE, with an Allison engine. Carbureted and non turbo, it was a failure. The a/c was re-engined with the Spit's Merlin, (eventually made under license by Packard) then fitted with its Belly tank, and there you have it.

Sharing the specs and patents was less than important when the B-17s couldn't reach Berlin w/o losing escort (fighter range issues). The Mustang arguably ended the European War. It certainly gave Hitler's laundress some repellent work, eh??

[barit1]

Yeah, but the Brits called their first batch the Mustang Mk I not Apache. The Apache was the US dive-bomber A-36 version (which was a political animal, apparently, funded from a different wallet...).

The Mustang name stuck for all other versions and customers. :ok:

[Brian Abraham]

P-51D root

http://www.ae.illinois.edu/m-selig/ads/afplots/p51droot.gif

Tip

http://www.ae.illinois.edu/m-selig/ads/afplots/p51dtip.gif

The cusp on an aerofoil (not all have them) refers to an aerofoil where the trailing edge is reflexed down forming a concave profile on the lower surface at the trailing edge. Typical of super critical aerofoils as here.

http://www.aerospaceweb.org/question/airfoils/supercritical/whitcomb.gif

[PBL]

barit and Jane,

It wasn't so obvious to me what ["crest"] meant, because I could think of two plausible meanings. One was point of maximum thickness; the other was point of maximum upwards deviation from chord.

Of course my suggestions are also ambiguous, because of where the "point" might be located - on the surface, or on the chord (which is normally taken to be the axis of coordinates).

I asked by aerodynamics guru, who said he understood it as meaning the highest point on the upper surface of the wing, and pointed me to Shevell, (his edition p193; my, first, edition, p188, first page of Chapter 12), where it is defined as the "point on the airfoil upper surface to which the freestream is tangent".

So, yes, it seems to be a common term, but it means the second of my proposed definitions, not the first!

PBL

[Jane-DoH]

barit1,

I find it most interesting that the NACA research on early laminar-flow airfoils found its first implementation in an aircraft designed for the export market.

Yeah, it is unusual. Regardless, the P-51 ended up one as the USAAF's best fighters. Fast, nimble, and possessed sufficient range to escort strategic bombers to and from their targets.

The British were visiting US manufacturers, and as the story goes, they asked NAA to become a second source for the Curtiss Kittyhawk. NAA countered with their own design, the NA-73, incorporating US taxpayer-funded research, and won the British contract.

They did if I recall, buy the plans for the Curtiss P-40 though. I don't know if any of the P-51 was derived from the P-40, though I suppose there are some superficial resemblances.


bearfoil,

Interesting point. The P-51 was initially supplied to the British as the APACHE, with an Allison engine.

Yeah, the V-1710

Carbureted and non turbo, it was a failure.

Why was the USAAC/USAAF so averse at first to using turbochargers? They work better than superchargers, and the technology existed since at least 1918.


Brian Abraham,

The cusp on an aerofoil (not all have them) refers to an aerofoil where the trailing edge is reflexed down forming a concave profile on the lower surface at the trailing edge. Typical of super critical aerofoils as here.

Yeah, the instant I saw the cross section I noticed the parallels. A supercritical foil is flatter on the top, a little blunter in the front, with the trailing edge drooped, and the cusp on the bottom side.

I assume with the shape of the foil being what it was, they weren't just trying to produce laminar flow over the wing, but to also weaken shockwave formation at high speeds (That or they just got lucky with the latter...)


PBL,

Thanks for saying what "crest" means. I'd not heard that term before.

I actually thought that was a common aerospace engineering term.

It wasn't so obvious to me what it meant, because I could think of two plausible meanings. One was point of maximum thickness; the other was point of maximum upwards deviation from chord. You will appreciate the two are not necessarily the same, in particular for convex-concave airfoils, although I guess they mostly are for biconvex airfoils - and of course for symmetrical ones!

I suppose when I said it I was thinking of the point of maximum upwards deviation from chord as well as the thickest point on the wing. I didn't actually give it as much thought (the fact that the two are not necessarily the same) as I probably should have.

[bearfoil]

Jane-DoH

I think at first, North American wasn't into the "Spirit" of the fight.

Superchargers were of course in service. The Lockheed "Lightning" or P-38, had turbocharging, each unit was aft of the Engine mounted on the Boom. The engines were contra rotating (There was a Left, and a Right, problematic in the field). This a/c was developed pre War, by Kelly Johnson, one of his first masterpieces. So turbo was not on the Apache, but one will have to admit the P-51 iterated into one beauty.

The wing is essentially symmetrical. The Angels are in the details.

cheers

bear

[PBL]

barit and Jane,

It seems I just munged my original note, but it doesn't matter.


It wasn't so obvious to me what ["crest"] meant, because I could think of two plausible meanings. One was point of maximum thickness; the other was point of maximum upwards deviation from chord.

Of course these suggestions are also ambiguous, because of where the "point" might be located - on the surface, or on the chord (which is normally taken to be the axis of coordinates).

I asked my aerodynamics guru, who said he understood "crest" as meaning the highest point on the upper surface of the wing, and pointed me to Shevell, (his edition p193; my, first, edition, p188, first page of Chapter 12), where it is defined as the "point on the airfoil upper surface to which the freestream is tangent".

So, yes, it seems to be a common term, but it means the second of my proposed definitions, not the first!

PBL

[HazelNuts39]

it is defined as the "point on the airfoil upper surface to which the freestream is tangent".
So, yes, it seems to be a common term, but it means the second of my proposed definitions, not the first!Not exactly. Shevell's depends on the angle of attack. Thinking of the airfoil as such, I think your (and your aerodynamics guru's) definition is better than Shevell's.

regards,
HN39

[PBL]

Not exactly. Shevell's depends on the angle of attack.

Good point! I'd missed that.

The aerodynamic significance of the crest, according to Shevell, is debated: "largely an empirical matter". One idea is that, in the transonic regime, supersonic flow forward of the crest does not contribute much to drag, whereas supersonic flow behind it would contribute a lot to drag, because of the "resulting low pressures (suction) on the aft-facing surface". Another possible explanation is that the crest represents the minimum distance between airfoil upper surface and (undisturbed) free stream, and if Mach > 1 at this point the "flow will accelerate in the diverging channel behind the crest, [leading] to a high supersonic velocity, a strong suction and a strong shock".

This suggests that the AoA-dependent definition of "crest" is aerodynamically significant in the transonic regime. Whereas I don't see at present that my second definition has much aerodynamic meaning at all - but I am willing to be educated!

PBL

[cwatters]

Does this count? Circa 1923..

Autogyro-C4 | Aircraft | (http://www.fiddlersgreen.net/models/aircraft/Cierva-C4-autogyro.html)

"The rotor blades were of Eiffel 101 symmetrical section 28 in wide"

[cwatters]

1929..

Albatros L 79 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Albatros_L_79)

1926..
Google Books also finds an edition of Flight from 1926 that appears to refer to a monoplane with a symetrical section and full span flaps tested at Farnborough...but only snippet vew prevents me being sure and identifying which aircraft.. Page 613..

Flight International - Google Books (http://books.google.co.uk/books?ei=ZxEnTZTqJZODhQfVps3RAg&ct=result&id=XqHoAAAAMAAJ&dq=racing+aircraft+symmetrical+section&q=symmetrical)

[barit1]

Jane-DoH:
Why was the USAAC/USAAF so averse at first to using turbochargers? They work better than superchargers, and the technology existed since at least 1918.


The Army Air Corps was NOT averse to turbos. Republic, Lockheed, and Curtiss all built prototypes using Army-specified turbos, and the P-47 and P-38 (both with innovative layouts) won production contracts. Likewise the B-17 and B-24.

Had NAA proposed the Mustang first to the US Army, it likely would have had a turbo just to win the contract; but the British were first to the table, and (at that time) they had little use for the turbo. The British even bought "P-38s" (Lockheed 322) hobbled by lack of turbosupercharging.

In fact, the Army flight-tested a LaPere bipe with a GE-turbosupercharged Liberty engine in 1919, setting a new altitude record in the process. In 1936 they had Lockheed build the XC-35 research aircraft with turbos and a pressurized fuselage - the first aircraft to used the monocoque skin as a pressure vessel.

New question: What was the first aircraft to use supercritical airfoil AND turbosupercharged engine(s)?

[Brian Abraham]

My apologies for introducing cusps into the conversation when I should have been researching crest.

New question: What was the first aircraft to use supercritical airfoil AND turbosupercharged engine(s)?

You sure you don't mean laminar airfoil and turbocharging barit? I know the answer to that one.

[BobM2]

The Army Air Corps was NOT averse to turbos. Republic, Lockheed, and Curtiss all built prototypes using Army-specified turbos, and the P-47 and P-38 (both with innovative layouts) won production contracts. Likewise the B-17 and B-24.
You are absolutely right barit & don't forget the Bell XP-39 that had excellent performance with a turbo, but so equipped had no room left for guns & ammo. The AAC were so enamored of turbos that they refused to let Allison spend any money to develop two-speed or two-stage superchargers for their V-1710. All high altitude applications would be turbo-charged. When no one except Republic, with their huge P-47, was able to develop a successful single-engine turbo fighter, the US was left with P-39, P-40, P-51A that were dogs at altitude.

Of course, the pre-war AAC bomber boys thought their high-flying formations of B-17's & B-24's didn't need fighter escort. They paid the price in Europe with greater losses than the Marines in the S. Pacific.

[ChristiaanJ]

As a non-engine freak, can I ask a rapid question?
"What's the difference between a supercharger and a turbocharger?"
As I understand it, a "supercharger" is a compressor driven from an auxiliary gearbox on the engine shaft, while a "turbocharger" or "turbosupercharger" is a compressor driven from a turbine in the engine exhaust, both feeding the compresed air back into the engine inlet manifold.
Right or wrong?

[Iron Duck]

The wing is essentially symmetrical. The Angels are in the details.

Slightly tangentially, I've read that the Comet 1 had a symmetrical aerofoil. Why would a jet transport require that? It seems to have been the cause of its ground stall.

[bearfoil]

ChristiaanJ

Hi. To me, a supercharger is a device used to increase gas pressure in the combustion chamber, any device. Turbocharger, or Turbosupercharger are self explanatory. A purely mechanical device, driven by sapping some of the available energy from the crankshaft, is a Blower.

A nifty combination is the Turbo compound system, used in something of reverse fashion. The Exhaust turns a turbine that drives an intake turbine, and excess energy is replaced via a geared shaft at the crankshaft, making theoretical use of "all" the tapped energy, and increasing dramatically the net Power available to drive a Propellor. It was used on the Corn Cob engine, the four row seven cylinder per bank on the Connie. The exhaust from the exit to the airstream of the system would turn the tip of the exhaust White. It was quite dramatic and prompted more than one passenger to inquire, "Is that normal?".

Iron Duck I want to say that the Bell X-1 wing was symmetrical.? The body had a purpose built shape of a .45 caliber bullet, the designers agreed that that projectile went super, and I think that is a true story.

[BobM2]

As a non-engine freak, can I ask a rapid question?
"What's the difference between a supercharger and a turbocharger?"
As I understand it, a "supercharger" is a compressor driven from an auxiliary gearbox on the engine shaft, while a "turbocharger" or "turbosupercharger" is a compressor driven from a turbine in the engine exhaust, both feeding the compresed air back into the engine inlet manifold.
You are correct ChristiaanJ. Supercharger is mechanically driven, turbocharger is exaust driven. Turbocharger is more efficient since it does not take power from the crankshaft.

[barit1]

BA asks me -You sure you don't mean laminar airfoil and turbocharging barit? I know the answer to that one.

Well, OK, I misspoke.

And offhand, I DON'T know the answer.

bearfoil:

You have a couple different engines/systems confused.

A "baseline" supercharger is a centrifugal compressor, gear-driven from the crankshaft, at perhaps 10:1 drive speed.

A turbosupercharger uses exhaust gases to turn a turbine and thus a centrifugal compressor. It's mechanically separate from the engine, and has been used on many installations including the P&W Wasp Major R-4360 "corncob". But that was NOT the Connie engine.

The Super Connie (and DC-7) used the unique Wright Turbo Compound engine, with exhaust-driven power recovery turbines (3 of them, each fed from six cylinders) geared into the crankshaft to send more "free" horsepower to the engine, gear-driven supercharger, and prop.

[Mechta]

The advantage of the turbocharger is that its speed is determined by the density of the air it is compressing, to some extent independently of the engine rpm. This means as you fly higher, and the incoming air is less dense, it will rotate faster until the air exiting the compressor is at approximately the pressure it would be at a lower altitude.

The crankshaft driven supercharger on the other hand will run at the same speed regardless of altitude (for a given engine rpm) so its effectiveness reduces with altitude. The most efficient way round this would be a variable speed drive to the supercharger, so it speeds up with altitude. Some Merlins had a two speed supercharger as a way of partially overcoming this. An less efficient method is to dump some of the output of the compressor at low altitude, and close the dump valve as altitude increases.

[Iron Duck]

Bearfoil

I want to say that the Bell X-1 wing was symmetrical.? The body had a purpose built shape of a .45 caliber bullet, the designers agreed that that projectile went super, and I think that is a true story.

I'm sure you're right; I recall reading a similar story. However, to the best of my knowledge the DH Comet 1 was not designed ever to go intentionally supersonic, but I believe had a symmetrical aerofoil, although I have no idea whether it was also laminar. Does anyone know why, especially as it was quickly exposed as a major liability?

[bearfoil]

Iron Duck

deHavilland had some brilliant wins, and some misses too. Was it the swallow that took Geoffrey? I don't check anything I write, first of all, I think anyone can go wikigoogle and then write here, but why? Also, there are so many pedants and wiseacres here, I always find out what's what, and sometimes I throw in some goof, to tease. Bad Bear.

The Comet was star crossed, A beautiful expression of the Art, except the tail. It was some butt ugly tail feather, imo.

cheers bear

[Iron Duck]

Bearfoil

The Comet was star crossed, A beautiful expression of the Art, except the tail. It was some butt ugly tail feather, imo.

Sure, but at the risk of sounding like a cracked record, why did it have a symmetrical aerofoil, if it did?

[BobM2]

You've got that a little backward Mechta. The turbocharger output is controlled by a WASTEGATE, a variable valve in the exhaust pipe ahead of the turbo that directs exhaust gas either through the turbo or bypass to atmosphere. At low altitude, where little boost is needed, the wastegate is mostly open, bypassing the turbo. As altitude increases, the wastegate gradually closes to direct more flow through the turbo & therefore increase its rpm & output up to the rpm limit of the turbocharger. Properly sized & controlled, the turbo can maintain sea level manifold pressure to any altitude.

The mechanical supercharger does loose with altitude & to overcome this, two speed & later two-stage (one blowing into another) supercharging were employed in later model Mustangs, Spitfires, etc to maintain power above thirty thousand feet.

Boosting air pressure, whether by mechanical or turbo, leads to greatly increased intake air temperature, which is not conducive to high power output. To counter this, complex intercooler & even aftercooler heat exchangers were employed in the intake downstream of the supercharger to reduce intake air temp & prevent detonation. Very high octane fuels had to be developed to work in these highly boosted engines at high altitude.

All of this development, done some 70 years ago during the emergency of a world war, is now beginning to show up in autos, where a tiny 2 liter four cylinder turbocharged & intercooled engine can produce the 300 horsepower of yesterdays V8 at a fraction of the fuel consumption.

[Jane-DoH]

bearfoil,

The Lockheed "Lightning" or P-38, had turbocharging, each unit was aft of the Engine mounted on the Boom.

I know the P-38 had turbos, which had to do with the high-altitude requirement. Regardless, the USAAC didn't seem to believe that high altitude performance was very important in fighter-aircraft until around the time of WW2.

The engines were contra rotating (There was a Left, and a Right, problematic in the field).

I didn't know that the P-38 had that feature, though I knew the Allison V-1710 was designed with the ability to turn the crankshaft clockwise or counter-clockwise

This a/c was developed pre War, by Kelly Johnson, one of his first masterpieces.

Yup, it was developed in 1938 as an interceptor. Truthfully the aircraft was technically a heavy-fighter/interceptor. At the time the Army felt that fighters should only be single engined and have no larger than 500 pounds of weapons; Two USAAC Lieutenants, Gordon Saville and Benjamin Kelsey decided to call the aircraft an interceptor to bypass the requirements. They wanted 1,000 pounds of bombs, and up to two engines.


barit1,

The Army Air Corps was NOT averse to turbos. Republic, Lockheed, and Curtiss all built prototypes using Army-specified turbos, and the P-47 and P-38 (both with innovative layouts) won production contracts. Likewise the B-17 and B-24.

Well, the mid to late 1930's, they started using turbochargers on bombers, but they largely felt that most fighters didn't need high-altitude capability; the P-38, P-47, (and technically the P-51) featured turbochargers because they were classified as interceptors (which was simply used to get around inflexible Army Air Corps requirements concerning fighters); once WWII was underway, turbocharged designs became more common.

In fact, the Army flight-tested a LaPere bipe with a GE-turbosupercharged Liberty engine in 1919, setting a new altitude record in the process.

Actually, that was in 1918. I'm not sure why it took them until the mid 1930's before they started using them in aircraft though, regardless, the Army seemed to only see their use as being important in bombers and transports which were designed to fly at high-altitudes; they didn't feel high-altitudes were important in a fighter.


Brian Abraham,

You sure you don't mean laminar airfoil and turbocharging barit? I know the answer to that one.

Probably the P-51...


BobM2,

Of course, the pre-war AAC bomber boys thought their high-flying formations of B-17's & B-24's didn't need fighter escort.

Actually, not every air-power advocate felt that way

* General Giulio Douhet did, especially by the time he wrote "Command of the Air".
* General Billy Mitchell did not, and stated that fighter escort was essential to a strategic bombing campaign
* The Bomber Mafia consisted of a number of people who held a variety of views
- Some were inspired by large gun-bristling bombers similar to the Caproni Ca.5. There were some who felt that they could simply fend for themselves provided they were fitted with loads of turrets and heavily armored and basically "the bomber would always get through".
- Most actually felt that maneuverable fighters were inherently useful (though the exact degree this was felt varied). Regardless, they failed to think up a design that would meet the range requirements while still retaining sufficient agility (and possibly dealing with various Army requirements for fighters), and as a result, they gave up on the idea of using fighters and went with the idea of building large, heavy, gun-bristling bombers instead.

They paid the price in Europe with greater losses than the Marines in the S. Pacific.

I don't know the exact numbers, but if I recall, they were routinely losing 20% of their bombers. Most people don't really think of this, but while modern-day bombers have a crew of 2 to 4; back then bombers had crews of 10 (all the turret operators). When a bomber went down, you could lose up to 10 people.


Mechta,

The advantage of the turbocharger is that its speed is determined by the density of the air it is compressing, to some extent independently of the engine rpm. This means as you fly higher, and the incoming air is less dense, it will rotate faster until the air exiting the compressor is at approximately the pressure it would be at a lower altitude.

Was the rotational velocity of the turbocharger supersonic on designs of that era?

[Turbine D]

Jane-DoH

Perhaps this might help, an old reprinted article from 1943 from the folks that made the most in the USA at that time. In the old days they called them Turbosuperchargers, later, shortened to turbochargers. :ok:

The turbine blades (called buckets in those days) were made from Vitallium, an alloy of 60% cobalt, 20% chromium, 5% molybdenum, and a few other elements. The alloy was invented for use in dentistry and artificial joints, because of its light weight (at that time, not today) and resistance to corrosion. It was used for components of turbochargers because of its thermal resistance. Vitallium was developed by Albert W. Merrick for the Austenal Laboratories in 1932.

The Turbosupercharger and the Airplane Power Plant (http://rwebs.net/avhistory/opsman/geturbo/geturbo.htm)

Turbine D

[BobM2]

I'm not sure why it took them until the mid 1930's before they started using them in aircraft though, regardless, the Army seemed to only see their use as being important in bombers and transports which were designed to fly at high-altitudes; they didn't feel high-altitudes were important in a fighter.
Actually the AAC had a few turbocharged aircraft in the '20s but...the early turbos were expensive & not too reliable. Funds were short in the '30s & manufacturing & materials available were not up to the challenge of producing a reliable device that had to live at 20,000 rpm in an environment of 1,600f in the exhaust stream. The AAC remained committed however & succeded in producing tens of thousands of very successful turboed aircraft in the '40s. So far as I know, no other country, allied or axis, produced even one.


Well, the mid to late 1930's, they started using turbochargers on bombers, but they largely felt that most fighters didn't need high-altitude capability; the P-38, P-47, (and technically the P-51) featured turbochargers because they were classified as interceptors (which was simply used to get around inflexible Army Air Corps requirements concerning fighters)


Once again, funds were short. The B-17 in 1935 was light years ahead but Congress would not fund it. They bought hundreds of the useless but much cheaper B-18. When the AAC bomber boys did later secure funding for a few dozen YB-17s, they impressed Congress with mass long range flights to S. America, intercepting the Italian liner Rex 700 mi out to sea & similar stunts to show the American people that they could defend the US at long range unaided with their "Flying Fortress". That was all America cared about at that time. This strategy enabled the bomber boys to get the meager funding available at the expense of the fighters. Offensive single engine single seat fighters were apparently not part of the equation as none were envisioned to have the range or endurance to even participate. Attempts were made to produce a viable single engine turboed fighter (YP-37, XP-39) but once again, the technology was not up to making it compact, reliable, & simple enough.

Other thoughts:

No P-51 either Allison or Merlin ever had turbocharging

Billy Mitchell, the most forward-thinking General in army aviation, was canned by the "old guard" ground officers in the mid '20s, so had no influence on events of the '30s.

No turbo operates supersonically.

Turbine D has provided a great link.

[Jane-DoH]

BobM2,

Actually the AAC had a few turbocharged aircraft in the '20s but...the early turbos were expensive & not too reliable.

What aircraft were those?

So far as I know, no other country, allied or axis, produced even one.

I was under the impression that the Germans and British were ahead of us when it came to turbocharger development in fighters.

Offensive single engine single seat fighters were apparently not part of the equation

They weren't part of the equation because they couldn't think of a design that would meet the range-requirements to escort the bombers as well as maintain maneuverability, maybe funding might have been an issue too, but the Bomber Mafia did see value in fighters if they could have achieved the range to escort the bombers.

No P-51 either Allison or Merlin ever had turbocharging

Really, I was always under the impression that the Merlin version did... if you're right, you learn something new every day

Billy Mitchell, the most forward-thinking General in army aviation, was canned by the "old guard" ground officers in the mid '20s, so had no influence on events of the '30s.

That I know, still he was a big proponent of using fighter escorts. He also was a big advocate of developing turbochargers, reliable gunsights, and aerial-torpedoes.

Fascinating to think of what would have happened had he succeeded

No turbo operates supersonically.

Just to be clear we're talking about the same thing, you mean a supersonic tip velocity due to rotational speed right?

[Brian Abraham]

The only allied aircraft to use turbocharging (off the top of the head) during WWII were the the P-38, P-47, B-17 and B-24. The P-51 did not use turbocharging. The P-38 was a flop in the European theatre, the turbocharging being part of the problem. The 8th Air Force, being so dissatisfied with the aircraft, gave Rolls Royce a 38 to be fitted fitted with Merlins as a test to over come the short falls, but a stop was put to the exercise by Washington, presumably for political/industrial reasons ie leaving Allison without work. The 8th in any event got rid of the 38.

The Comet used a NACA 63A116 at the root and a NACA 63A112 at the tip. Hence not symmetrical, I'd be interested in any reference that says otherwise.

barit, re the turbocharging and laminar flow I put up the B-24. The Davis airfoil was adopted by Consolidated because of its advanced properties, but at the time they were not aware that those properties came because of its laminar flow. The P-51 generally takes the prize as the first laminar, but that may be qualified by being the first purpose designed laminar. Bit like Yeager being the first to crack the barrier, not really, George Welch in the F-86 beat him to it by two weeks. The difference was Welch did it in a dive whereas Yeager did it in level flight. Again politics were heavily involved in the claim that Yeager was first.

[Iron Duck]

The Comet used a NACA 63A116 at the root and a NACA 63A112 at the tip. Hence not symmetrical, I'd be interested in any reference that says otherwise.

Ah. I'm sure I remember reading in accounts of the Comet's history that it at first had a symmetrical aerofoil. Must be the early onset Alzheimer's. I also remember reading that the leading edge profile was modified to overcome the ground stall problem. Would that be considered to have altered the aerofoil's definition, and therefore, name?

[barit1]

Brian Abraham:

The Davis airfoil was adopted by Consolidated because of its advanced properties, but at the time they were not aware that those properties came because of its laminar flow.

Fascinating. Laminar flow via serendipity.

30s race pilot and designer Ben Howard observed a racing Monocoupe (http://en.wikipedia.org/wiki/Monocoupe_110_Special) (from the wrong end, as he tells it) and deduced the reason for its efficiency and success - and capitalized on that observation when he built his hugely successful DGA-6 (http://en.wikipedia.org/wiki/Howard_DGA-6).

Monocoupe, in the meantime proved Howard right and themselves wrong by diverging from their winning formula; their earlier design success was pure serendipity (no disturbances in the downwash from the wing upper surface).

[bearfoil]

Brian

One rarely hears that story. I have been privileged to meet and speak with the General. Obviously, he takes no pleasure in discussing even Welch's grape juice, let alone the X86.

One believes The AAC could have found a more likable first M guy. Yeager is a caricature of himself, arrogant, dismissive and uncomfortable to be around. It is pretty cool to watch him take off in his friend Bart's Husky each Saturday morning, but really, not too many people like to be around him. He is in better mettle when he is paid to be nice. (He demands money to meet people). Then again, our encounter was free, perhaps that is why he was such an a*****e.

bear

[galaxy flyer]

Barit1 & Brian

If you read your Fate is the Hunter, you will find all were not happy with the Davis wing. Gann reports it couldn't "carry enough ice to chill a highball" which was a problem for C-87 ops. It was a good airfoil for high altitude bombing and the like, though.

Bear--that is his unfortunate reputation within the AF. I thought his book for outrageous bollocks-self-referential to an extreme.

GF

[mike-wsm]

Some faster airplanes had symmetrical wings, I'd guess the F-104 was one. Not sure about FD2, Bristol 188, Bristol 221. And aren't helicopter blades symmetrical?

edit - interesting to use barit1's list and search for 'biconvex', that finds quite a few more symmetricals
.
AerMacchi MC.72 - Schneider Trophy racing seaplane (1931)
AerMacchi M.67- Schneider Trophy racing seaplane (1929)
AIDC Ching-Kuo IDF - Indigenous Defence Fighter (1989)
Albert A-10 - Possibly (1926-33)
Breda 19 - Biplane Fighter (1928)
Bristol 188 - Stainless Steel twin (1982)
Canadair CL-201 CF-104
Canadair CL-90 CF-104
Focke Wulf A43 Falke - Light utility Monoplane (1932)
Handley Page HP.115 - High sweep delta (1961)
Helewan HA-300 - Egyptian fighter (1964)
Leduc O.21 - French ramjet (1947)
Lockheed 246 F-104 - (1954)
Lockheed XQ-5 - M4.3 drone (1951)
Lockheed X-27 Lancer - not flown
Lockheed X-7 - ramjet flying testbed (1951)
Miles Gillette Falcon - modified M3B (1946)
Miles M.52 - supersonic research aircraft (not flown)
Nord CT.41 PQM-56A - M3.1 target drone (1959)
Renard R.31 - Belgian parasol monoplane (1932)
Republic AN/USD-4 - not known, possibly drone
.
The Albert TE-1 dates from 1926 and the Albert A-20 is from 1933 so presumably the Albert A-10 is from the same era. The Breda 19 is contemporary and the Aermacchi Schneider Trophy planes a little later. Possibly other Schneider Trophy planes may also have symmetrical airfoils.
.
Our neighbour who was an eminent Bristol Engines man bought a car for his wife and occasionally drove it to work with a broad grin on his face. It was a little green Hillman Imp with the Bristol registration WHY188.
.

[Brian Abraham]

you will find all were not happy with the Davis wingThere was a lot not to like about the B-24 if you read what many of the crews had to say about it, leaking fuel tanks, inability to accept battle damage, general flying qualities among them.

Iron Duck, the aerofoil was modified later with a leading edge droop following the accidents, but the base aerofoil was still asymmetrical.

[barit1]

I had an instructor who flew B-24's. He had little good to say about it, except that it delivered the goods.

[bearfoil]

mike wsm

The F-104 is an odd duck. When looking down the wing tip, Tank removed, the wing shows a definite symmetry top/bottom. the deal is, it is shaped like a noodle. It is "S" shaped, a cuff-like (droop) leading edge, an up swoop, a down, then straight at the TE.

I have not researched this, I more or less think Kelly Johnson did no wrong. No one I know calls it a fighter, it is an interceptor, very big difference. Up Kill Down.

[mike-wsm]

bearfoil

Interesting shape, can you post a sketch? Or email to me and I'll post. When I was a kid our silhouette models of deltas had s-shape wing for stability.

[Jane-DoH]

Brian Abraham

The Davis airfoil was adopted by Consolidated because of its advanced properties, but at the time they were not aware that those properties came because of its laminar flow.

Just to be clear, Consolidated didn't know, or did David R. Davis not know?


barit1

30s race pilot and designer Ben Howard observed a racing Monocoupe (from the wrong end, as he tells it) and deduced the reason for its efficiency and success - and capitalized on that observation when he built his hugely successful DGA-6

You mean he produced an airfoil similar to the p-51 (with the crest further aft than usual)?


bearfoil

The F-104 is an odd duck. When looking down the wing tip, Tank removed, the wing shows a definite symmetry top/bottom. the deal is, it is shaped like a noodle. It is "S" shaped, a cuff-like (droop) leading edge, an up swoop, a down, then straight at the TE.

Can you post a picture?

[barit1]

You mean he produced an airfoil similar to the p-51 (with the crest further aft than usual)?

No, it was more elementary. The Monocoupe used a high wing with the upper surface continuous with a flat upper surface of the aft fuselage, and no antennae or other obstructions in this high-velocity flow field. The DGA-6 simply duplicated this principle - albeit in a larger, higher-powered aircraft with a different airfoil.

The Howard DGA-6 was the only purpose-built racer to evolve into a successful series of commercial designs.

[mike-wsm]

BobM2
"No P-51 either Allison or Merlin ever had turbocharging"
Jane-DoH
"Really, I was always under the impression that the Merlin version did... if you're right, you learn something new every day"

Bob is right. The Merlin was supercharged, not turbocharged. And no, I'm not going to explain the difference. Go and look it up. Or have a good look at this pic.

http://www.flightglobal.com/airspace/media/aeroenginespistoncutaways/images/5685/rolls-royce-merlin-supercharger-cutaway.jpg

[Jane-DoH]

mike-wsm

Bob is right. The Merlin was supercharged, not turbocharged.

So they managed to retain good performance by using a dual-staged supercharger with twin-speeds?

And no, I'm not going to explain the difference. Go and look it up. Or have a good look at this pic.

I do know the difference between a turbocharger and a supercharger....

[mike-wsm]

So they managed to retain good performance by using a dual-staged supercharger with twin-speeds?

Read the book.

[Jane-DoH]

mike-msm

What book are you even talking about?

[bearfoil]

JaneDoH

How could you not know "JANES, all the world's aircraft"

[ChristiaanJ]

Jane-DoH,

I would think Mike was referring to "Not Much of an Engineer" by Stanley Hooker... which has most of the story.

CJ

[mike-wsm]

The F-104 is an odd duck. When looking down the wing tip, Tank removed, the wing shows a definite symmetry top/bottom. the deal is, it is shaped like a noodle. It is "S" shaped, a cuff-like (droop) leading edge, an up swoop, a down, then straight at the TE.

All thanks to ChristiaanJ for some pics of F-104 wingtips with ancilliary hardware removed. I've cropped and enhanced a bit but the geometry is as original photo.
.
http://mjr.org.uk/pprune-025.jpg
.
http://mjr.org.uk/pprune-026.jpg
.

[Turbine D]

JaneDoH

There are some great sources of information for questions you have posed regarding the Rolls Royce Merlin. Just "Google" Merlin engine and this is what you get, Page 1:

Rolls-Royce Merlin Engine - Great Britain (http://www.aviation-history.com/engines/merlin.htm)

Rolls-Royce Merlin - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Rolls-Royce_Merlin)

Regards,

Turbine D

[bearfoil]

mike-wsm

Yo, dassit. One can see a very supercritical aspect, and obviously, not symmetrical. You can also understand why when I was ten, and a Starfighter pilot told me the wing was carved from billet, I believed him. Thin to win. Now, can we discuss the "anhedral"?

bear

[PBL]

Let me put in my vote for this as a fine thread. I am learning a bunch of stuff, all of which I don't really have the time to look up, but which I am glad I now know. For example, that the Merlin had dual superchargers and how they were configured; the exact shape of an F104 wing; the list of airfoils on the U.Ill WWW site (which apparently one of my guys knows about because he designs airfoils for X-Plane as a hobby); the name of a book which contains details of Merlins; the names of lots of airplanes with symmetrical airfoils, a feature of which I was not aware they had (I had thought symmetrics were for aerobatics, for all the usual reasons). (I even sent a note off to Boeing about the XB-15, which was acknowledged but remains unanswered. It's hard to believe that Boeing doesn't have a company historian.) In particular, many thanks to Jane for originating the thread and asking all the questions that the rest of us would like to ask but don't get around to.

PBL

[HazelNuts39]

It's hard to believe that Boeing doesn't have a company historian.The Boeing Company is mainly interested in 'Shareholder Value'. I believe there is an association of (ex)Boeing employees interested in history, which also keeps a small museum going, with some support from the Company. Unfortunately I don't know if they can be reached on the WWW.

[Brian Abraham]

One can see a very supercritical aspectNot supercritical Bear.
the Merlin had dual superchargersThe Merlin came in a variety of versions.

Single stage, one speed
Single stage, two speed
Two stage, two speed

[barit1]

Pratt & Whitney had an informal historian for many years (50s-90s), Harvey Lippincott (http://articles.courant.com/1997-01-01/news/9701010303_1_aviation-museums-mr-lippincott-aviation-industry). GE had a cadre of men who had worked on the first GE I-A engine, the Jet Pioneers Associaton (http://massmoments.org/moment.cfm?mid=117). I'm sure the tin-knockers have similar adjunct functions.

I've found that the retirees and informal archivists manage to present a more honest and balanced picture, than do the ones subject to current corporate whims.

[bearfoil]

Brian

Are you sure? I figured the chord was "flat on top" to escape the need for area ruling.
Was the wing thin enough to produce little Waist drag? The fuselage is rather 'unassuming' in section?? Also, the "inverted planform" of the wings, added to anhedral, made the a/c very "manouverable" ('unstable'). This I believed to be the Deal with the Devil that killed so many Germans. IE, a natural tendency to the Roll, requiring little if any draggy aileron input. The 104 could ill afford to kill any of its lift just to turn.

[mike-wsm]

It's hard to believe that Boeing doesn't have a company historian.

I had this problem with Bell when researching for a book many decades ago. They kept sending printed cards telling me to "contact my local library". This was a bit pointless, a library in the uk wouldn't know a lot about Bell designs. After a bit of though I wrote to their local library in Buffalo. The result was soooo surprising, a kind letter from the librarian with a whole stack of reference material and past company newsletters for the era I was interested in. She also said she had looked up the then President in the phone book and gave me his address. I wrote to him, explained what my interest and he went back into work, he still had an office there, and dug out all sorts of research material and photos. He converted a gap in the book into a really interesting section. So keep trying, in particular Seattle Public Library (http://www.spl.lib.wa.us/) and the local Museum of Flight (http://www.museumofflight.org/main-campus), they may have volunteers who will be happy to look through their archives and make copies for you.

[HazelNuts39]

mike-wsm;

thanks for the link to The Museum of Flight, which I was referring to because remembering a visit some years ago when it was still in the Red Barn. (Look it up in 'About the Museum', History).

regards,
HN39

[Annex14]

bearfoil

quote:
This I believed to be the Deal with the Devil that killed so many Germans. IE, a natural tendency to the Roll, requiring little if any draggy aileron input.

Hi Bear, please allow for a small addition. The "Deal with the Devil" was not that much the wing but the additions made to the original VMC interceptor desighn. It added about 2000 lbs to the weight without adequate improvements to engine performance. Some critics called the plane later " the egglayingsheepwoolbreedingmilkpig". Fact is it was very fast, stable weapons platform in normal flight envelope. The mentioned instability came in play on slow speed envelopes. During approach - app.speed 185kts - the plane became very soft through all axis. A frequent problem was "open nozzle", I only remember one attempt of landing in these condition that didn´t end in bail out.

Though I was civil, I worked a while dep. and app. control for a F-104 base. Later, when I held a "Red Card" for 8 years, because of other activities in my carreer, I applied for and was approved a low level mission on a TF 104. I must admit, even after more than 30 years still a milestone in my aviation life.
Jo

[BobM2]

So they managed to retain good performance by using a dual-staged supercharger with twin-speeds?

As I recall, the 2-stage 60 series Merlin was introduced in the Mk 9 Spitfire. This was necessary in 1941 to counter the threat of the new FW-190 which completely outperformed the Mk-5 Spit with its single-stage Merlin.

It should be noted that the first 2-stage supercharger was on the P & W R-1830 in the F4F-3 Wildcat. Unlike the AAC, the US Navy didn't pursue turbochargers or V12 engines ("we'll buy liquid-cooled aircraft engines when we convert to air-cooled submarine engines"). Ironically, the Navy found their lower altitude pacific war didn't require the two-stage blowers & later FM Wildcats (built by GM) used single stage Wright 1820's. They were lighter, cheaper, simpler & developed more sea level power to get the FM Wildcats off the short decks of escort carriers.

[Brian Abraham]

Brian

Are you sure?

Certainly am Bear. The supercritical airfoil was invented by NASA scientist Richard T. Whitcomb during the 1960's, and was first tested on a modified F-8 in 1971. Is designed for high subsonic and transonic, not supersonic, performance. It's use is confined to airliners, business jets and transports (C-17).

[Jane-DoH]

mike-wsm

All thanks to ChristiaanJ for some pics of F-104 wingtips with ancilliary hardware removed. I've cropped and enhanced a bit but the geometry is as original photo.

That looks very supercritical in nature, especially in the second picture you can see a definite inverse camber and due to the particular curvature, it looks like it would do very well supersonic. It would appear that the small curvature to the top was to compensate for the inverse camber on the bottom.


bearfoil

Now, can we discuss the "anhedral"?

Sure, as I understand it was added to deal with the size of the T-tail and something called a "wing-on-rudder" effect which, as I understand it was either a form of dutch-roll, or a tendency for rudder-application to roll the airplane. Adding some anhedral would fix the problem.

Interestingly, I have speculated that the anhedral could have also had an additional benefit (whether realized or an unintended consequence) of producing some kind of compression-lift effect. My reasoning was based on the fact that a wing with no sweep would have a shockwave along the whole leading-edge, and with it a pressure gain on any convex portion of the top and bottom of the wing; if you canted the wing down 10-degrees you'd have more pressure confined to the bottom.

This had to do with a curiosity of mine as to how the aircraft still retained a good degree of agility when supersonic. Straight wings experience large shifts in the center of pressure when transitioning from subsonic to supersonic speeds, which often results in high trim-drag. My guess is that the high-thrust available, the large tail, and the fact that the overall drag of the plane was low got around that. Still, L/D ratios drop when supersonic which affects sustained-agility. To some degree, ram-compression helps drive up thrust at supersonic speeds, but I figured the anhedral actually helped drive up the L/D ratio when supersonic and produced an overall better L/D ratio allowing improved sustained maneuvering performance.

Regardless, with the inverse-camber of the wing, it's L/D ratio would be good at supersonic speeds because inverse-camber works well when supersonic, and if the anhedral did actually produce a compression-lift effect by confining the pressure gain on the bottom that would explain a lot.


PBL

Let me put in my vote for this as a fine thread. I am learning a bunch of stuff, all of which I don't really have the time to look up, but which I am glad I now know.

I'm glad we're all of help

I even sent a note off to Boeing about the XB-15

The XB-15 had a symmetrical airfoil?


Brian Abraham

Not supercritical Bear.

True enough. It does have an inverse camber though


bearfoil

Are you sure? I figured the chord was "flat on top" to escape the need for area ruling.

I thought the F-104's fuselage shape did incorporate some area-ruling to it


BobM2

It should be noted that the first 2-stage supercharger was on the P & W R-1830 in the F4F-3 Wildcat. Unlike the AAC, the US Navy didn't pursue turbochargers

I'm surprised they didn't pursue turbochargers earlier. If I recall the F6F and F4U had them though...

[Brian Abraham]

I'm surprised they didn't pursue turbochargers earlier. If I recall the F6F and F4U had them though...No they didn't.

[Jane-DoH]

Brian Abraham

No they didn't.

So they used superchargers?

[Brian Abraham]

Jane, please do a modicum of research before clogging up these pages with nonsense questions.

[Jane-DoH]

Brian Abraham

Jane, please do a modicum of research before clogging up these pages with nonsense questions.

I remember in a google search awhile back a mention of a turbocharger was mentioned in regards to the F6F; I assumed the F4U would have one too as they were both designed around the same engine and both exhibited high performance. As an interesting note, if you did a wikipedia search you would find that the XF6F-2 did indeed have a turbocharger, but it was dropped in favor of a twin-speed supercharger.

(Regardless, I probably should have read the article about the F6F more carefully awhile back)

[Jane-DoH]

What was the first aircraft to have the crest moved further back than the typical 20% to 30% chord? Was the P-51 the first?

[gavinparish]

First aircraft to have a symmetrical airfoil?.... Easy, a paper plane.

[Jane-DoH]

gavinparish

LOL! I guess I can't really argue with that :rolleyes:

[DERG]

Robyn...a really good area of research is why WNGLETS have become used in many of the new designs. There is plenty of interest there and lots of puzzles as to just what makes the aircraft fly better. Don't you agree?

Regards

[Jane-DoH]

DERG

They're supposed to reduce vortex formation on the wing-tip, which also reduces drag. I assume this would have some effect on the downwash which is affected by the wingtip vortices...

[mike-wsm]

http://www.mh-aerotools.de/airfoils/images/winglt11.gif

[HazelNuts39]

mike-wsm;
Nice picture! I think that the leading edge feathers also act as slats in low-speed flight. I always find it fascinating to watch the tail in action, as it combines the functions of horizontal and vertical tail surfaces on an airplane.

regards,
HN39

[DERG]

They say a dog is worth 10 men when hunting. An eagle must be worth 100. Then there is the whole U.S. military icon stuff. "when diplomacy fails" etc...:ok: