Me-109S featuring blown flaps

[AeroFranz]

I searched the forum and found no mention of this...
There is an article written by Jon Guttman and originally published in the May 1999 issue of Aviation History about the history of the -109. There is a very brief mention of a blown flap system with no further explanation.

"The Me-109S would have featured blown flaps to improve its low-speed handling characteristics. "
you can find the full article here:
http://www.historynet.com/messerschmitt-me-109.htm

I am very curious because that would have represented one of the oldest applications of boundary layer control (at least that i am aware of). Does anyone have more information on this (or better yet a picture!)? Thanks!

 

[zuid99]

According to Nowarra's "Die Deutsche Luftrustung" the Me-109S was an attempt to improve the slow flying characteristics of the 109. A prototype was constructed/converted. Nowarra gives the designation of the prototype as V-24. Further development was allocated to Caudron Renault in France but nothing more came of it.

I seem to remember seeing a drawing of the system somewhere a long time ago but coudn't find it yesterday evening. I will look again tomorrow and post it of I find it.

Tom

 

[swampyankee]

I searched the forum and found no mention of this...
There is an article written by Jon Guttman and originally published in the May 1999 issue of Aviation History about the history of the -109. There is a very brief mention of a blown flap system with no further explanation.

"The Me-109S would have featured blown flaps to improve its low-speed handling characteristics. "
you can find the full article here:
http://www.historynet.com/messerschmitt-me-109.htm

I am very curious because that would have represented one of the oldest applications of boundary layer control (at least that i am aware of). Does anyone have more information on this (or better yet a picture!)? Thanks!

No; the Lachman-Handley Page slats were boundary layer control devices, as are slotted flaps. NACA's "laminar flow" airfoils, like the 1 and 6 series, are shaped to control boundary layers. If you restricting your discussion to active boundary layer systems, like suction or blowing, I've not found any earlier attempts for a system actually applied to an aircraft, except the aircraft that used devices like rapidly spinning cylinders as a boundary layer control device (they worked, but were not practical for service).

 

[sienar]

Excellent post newsdeskfan!
I believe there are some Messerschmitt patents related to boundary layer control that may be illuminating.

 

[swampyankee]

I searched the forum and found no mention of this...
There is an article written by Jon Guttman and originally published in the May 1999 issue of Aviation History about the history of the -109. There is a very brief mention of a blown flap system with no further explanation.

"The Me-109S would have featured blown flaps to improve its low-speed handling characteristics. "
you can find the full article here:
http://www.historynet.com/messerschmitt-me-109.htm

I am very curious because that would have represented one of the oldest applications of boundary layer control (at least that i am aware of). Does anyone have more information on this (or better yet a picture!)? Thanks!

No; the Lachman-Handley Page slats were boundary layer control devices, as are slotted flaps. NACA's "laminar flow" airfoils, like the 1 and 6 series, are shaped to control boundary layers. If you restricting your discussion to active boundary layer systems, like suction or blowing, I've not found any earlier attempts for a system actually applied to an aircraft, except the aircraft that used devices like rapidly spinning cylinders as a boundary layer control device (they worked, but were not practical for service).

I'm sure you're right. But the Me 109S is definitely a much neglected area of study. Apparently it was intended for carrier use and was based on the 109G-6. Both conventional and tricycle undercarriage arrangements were looked at - but goodness knows how the tricycle arrangement would've worked with that air scoop. Maximum speed was, gulp, 250mph!

I can't think of any piston-engined service, vs experimental, aircraft that used blown flaps, probably because piston-engined aircraft had, pretty universally, wing loadings that were too low to make the complexity of blown flaps worthwhile: it would make much more sense to use full-span trailing edge flaps, such as double-slotted Fowlers (these were used before WW2, first on the Italian M-32 [https://books.google.com/books?id=GzVIBAAAQBAJ&pg=PA367&lpg=PA367&dq=first+use+of+double-slotted+fowler&source=bl&ots=OR7L0kbHIk&sig=Bes_NgTkWfZgFU3PAl76eqEhj70&hl=en&sa=X&ved=0CDMQ6AEwA2oVChMI3OacuJuOxwIVgf-ACh0H4gcn#v=onepage&q=first%20use%20of%20double-slotted%20fowler&f=false], later on the A-26)

 

[AeroFranz]

I believe some of the earlier (active) BLC experiments were conducted in Germany and involved liaison-type aircraft testbeds fitted with fuselage mounted compressors providing blowing or sucking on the wing flaps. I don't have my books right now, but that's what i recall. These experiments were reprised in England post-war, and there are technical papers and flightglobal articles documenting this.


Here's a good summary in a flight archive article from 1954

 

[sienar]

http://worldwide.espacenet.com/publicationDetails/biblio?DB=EPODOC&II=119&ND=3&adjacent=true&locale=en_EP&FT=D&date=19400402&CC=GB&NR=519623A&KC=A
Much earlier then the S project. Willy Messerschmitt later (~1943) mentioned the importance of boundary layer control in attaining decent landing speed for supersonic aircraft.

 

[sienar]

DVL testing of blown flap for messerschmitt, dated December 1943

Its noted that the wing structure required near no modification, with the air being forced into the area aft of the spar.

 

[r16]

latest issue of Aviation History (?) mentions an Arado-232(?) with hydrogen peroxide power source for flap blowing but no details . Only refers that Germans had no industrial scheme to produce stuff in operational amounts . So , am ı to assume that powered a turbine ?

also mentioned by post #5...

 

[sgeorges4]

what was the fuselage who going to be used for this variant?

 

[Jemiba]

The drawing posted by Sienar suggests an E-version wing, and a Bf 109E would have been a
plausible choice for a pure experimental type, too, as already out of date in 1943, I think.

 

[newsdeskdan]

what was the fuselage who going to be used for this variant?

G-6

 

[iverson]

Forgive me if I'm missing something obvious. But, without more evidence, I'm skeptical that there was ever going to be a Bf109S with blown flaps.

First, the photo shows what looks like a pure test-bench configuration. The flap is full span, with no aileron for roll control. A large, static, probably electrically driven compressor supplies air through a bulky duct. Perhaps an operational fighter engine's compressor could provide enough air at takeoff. But the ducting and control doors would be bulky and, I'd expect heavy, even if they did not interfere with boost at altitude.

Second, what was the operational requirement? The Bf109's low-speed handling may not have been ideal. But, in 1943, it had been in service for six or so years. So surely handling was good enough for wartime?

My guess would be that this work was either the pure, blue-sky research that wartime Germany seems to have been so ready to indulge in or theoretical research connected with future jet aircraft and future high-thrust jet engines. The Bf109E wing just happened to be available and structurally convenient.

 

[newsdeskdan]

Forgive me if I'm missing something obvious. But, without more evidence, I'm skeptical that there was ever going to be a Bf109S with blown flaps.

First, the photo shows what looks like a pure test-bench configuration. The flap is full span, with no aileron for roll control. A large, static, probably electrically driven compressor supplies air through a bulky duct. Perhaps an operational fighter engine's compressor could provide enough air at takeoff. But the ducting and control doors would be bulky and, I'd expect heavy, even if they did not interfere with boost at altitude.

Second, what was the operational requirement? The Bf109's low-speed handling may not have been ideal. But, in 1943, it had been in service for six or so years. So surely handling was good enough for wartime?

My guess would be that this work was either the pure, blue-sky research that wartime Germany seems to have been so ready to indulge in or theoretical research connected with future jet aircraft and future high-thrust jet engines. The Bf109E wing just happened to be available and structurally convenient.

 

[iverson]

Please explain. I only see the string "Me109S" in a French document that does not refer to surface blowing.

 

[newsdeskdan]

Please explain. I only see the string "Me109S" in a French document that does not refer to surface blowing.

Trust me - the Me 109 S was a real project. It involved an Me 109 modified to provide air discharge over the wing in front of the ailerons and flaps in order to obtain a smooth air flow at low speeds. Two versions were projected, the main difference being the provision of a conventional or tricycle type of undercarriage (although exactly how the latter would work is unclear, since the nosewheel would need to retract into the space occupied by the intake for the air discharge system. No doubt a huge redesign would have been in order following on from the initial experimental version).
The point was to allow the Me 109 to operate from the deck of an aircraft carrier.

 

[iverson]

Your explanation makes a bit more sense.

But what provided the air? Supercharger bleed air? If so, do you have any idea of how was this was to be controlled/managed? how it was expected to affect engine output? what it weighed?

I'm also curious about the dates. My understanding was that carrier development stopped early in 1943. Was Me109S development carried on due to bureaucratic inertia or for another reason?

 

[iverson]

Also, how does the Me109S relate to the Me155 carrier project? The new wing and landing gear of the Me155 would seem to be a better solution to carrier-compatibility issues than surface blowing and a tricycle landing gear.

 

[newsdeskdan]

Your explanation makes a bit more sense.

But what provided the air? Supercharger bleed air? If so, do you have any idea of how was this was to be controlled/managed? how it was expected to affect engine output? what it weighed?

I'm also curious about the dates. My understanding was that carrier development stopped early in 1943. Was Me109S development carried on due to bureaucratic inertia or for another reason?

Air entered the scoop below the fuselage and was accelerated along a duct by a fan driven from the rear of the engine. The duct was divided into three, one leading along each mainplane and one exiting beneath the fuselage. The amount of air entering each could be controlled with valves. The ducts meant the Me 109 S couldn't use the normal coolant radiators so an evaporative cooling system was used. This meant fitting a 44 gallon coolant tank behind the pilot, which messed up the aircraft's c.g. so the fuselage had to be lengthened. The air ducts also prevented the undercarriage from retracting properly, and this problem seems never to have been satisfactorily rectified - as least as far as the French subcontractors knew.
Date-wise, the work carried on in France until the Liberation, after which point there doesn't seem to have been any further work done on it in Germany either. Why did it carry on so long? I don't know. I just know that it did.

 

[newsdeskdan]

Also, how does the Me109S relate to the Me155 carrier project? The new wing and landing gear of the Me155 would seem to be a better solution to carrier-compatibility issues than surface blowing and a tricycle landing gear.

As I've mentioned elsewhere, the carrier version of the Me 155 was dropped quite early on - probably at around the same time that work on the Me 109 S began circa autumn 1942. Why was the Me 155 carrier version dropped but the Me 109 S carried on for two more years? Again, I don't know. It's a research project in progress...

NB. Looking again at what Caudron says versus what the Messerschmitt evidence says, Caudron's estimate of having worked on the project for "nearly two years" might actually mean early 1943. The German evidence suggests things got started at Caudron in April '43. This would definitely place the beginning of the Me 109 S after the cancellation of the Me 155 carrier version.

 

[iverson]

Thanks! Any idea what the under-fuselage duct was for?

 

[newsdeskdan]

Thanks! Any idea what the under-fuselage duct was for?

It's not clear. For venting air you didn't want to go into the wings? Weights-wise, and I realise this doesn't tally with the real-life weights of the G-6, Caudron gives the Me 109 S's empty weight as 2216kg, the minimum take-off weight as 2397kg and the maximum take-off weight as 2675kg.

 

[sgeorges4]

For the trycicle type undercarriage,maybe something like the V23?

 

[sgeorges4]

also,do you have any drawing of the fuselage of this project or not?

 

[sienar]

The drawing posted by Sienar suggests an E-version wing, and a Bf 109E would have been a
plausible choice for a pure experimental type, too, as already out of date in 1943, I think.

The date on the DVL report I posted is from December of 1943, so presumably the work was done in the second half of that year. As the experiment was concerned with finding out the slot size and the effect of duct smoothness, using an E wing probably wasnt a big issue. And note that the slot ends before the end of the wingtip, at the approximate end point of the F and on series wing.

Why did it carry on so long? I don't know. I just know that it did.

Willy Messerschmitt discussed the use of blown control surfaces to obtain decent landing speeds in high speed aircraft at least as early as 1941/2. This idea for the same purpose is also mentioned by quite a few engineers in interrogation just after the war.

Perhaps the purpose of the S was two fold; a carrier aircraft that would also get some test data on blown flaps in a high wing loading aircraft. Or maybe the carrier aspect was just a flat out cover story for the french.

 

[dan_inbox]

Perhaps the purpose of the S was two fold; a carrier aircraft that would also get some test data on blown flaps in a high wing loading aircraft. Or maybe the carrier aspect was just a flat out cover story for the french.

The carrier aspect was most real with the "Flugzeugträger A" Graf Zeppelin under completion, at least until December 1942. That CV needed fighters.
After Hitler's volte-face about surface ships, then yes it was no longer the reason for further studies on the 109S.

 

[TomcatViP]

"Intrados" implies that the slots where situated under the wing. This would be pointless for the bliwn flap application as known today.

"Avion soufflé" means however "blown plane".
So two set of remarks (actually three):
-1. I doubt that a major issue such as a research on high lift device and blown flaps would have been left to a minor contractor in an occupied country
-2: Me 109G cooling flaps already introduced blown air to activate the no boundery layer, reduce drag and improve cooling
-3: given that project was part of a research to improve take-off and landing, given to my point 1, this drawing probably more reflect a minor side of this such as... Blowing compressed air under the wing to clear/screen (from) mud/sand on rough airfield. Remember the Russian campaign.

 

[newsdeskdan]

"Intrados" implies that the slots where situated under the wing. This would be pointless for the bliwn flap application as known today.

"Avion soufflé" means however "blown plane".
So two set of remarks (actually three):
-1. I doubt that a major issue such as a research on high lift device and blown flaps would have been left to a minor contractor in an occupied country
-2: Me 109G cooling flaps already introduced blown air to activate the no boundery layer, reduce drag and improve cooling
-3: given that project was part of a research to improve take-off and landing, given to my point 1, this drawing probably more reflect a minor side of this such as... Blowing compressed air under the wing to clear/screen (from) mud/sand on rough airfield. Remember the Russian campaign.

Caudron was only building the wing (with slots for blowing air over the wing) and modifying the G-6 fuselage. The modifications to the engine were being carried out by Daimler-Benz at Stuttgart, the 9000rpm fan system was being made by Zahnraderfabrik of Augsburg (as a sub-contractor of DB), the blower system was being built by the AVA at Gottingen and the electrical system required to operate it was being designed by VDM at Frankfurt. Messerschmitt itself was coordinating the project (and seems to have built mock-ups of it). So Caudron was only really doing what Messerschmitt regarded as 'the easy bit'.
Exactly what the point of creating the Me 109 S was is unclear. The 'S' itself is described as being 'purely experimental' and both Caudron itself and the British surmised that the system was 'probably' going to be used for short take-offs on carriers. But whether the system, assuming it was successfully tested, would actually have ended up being fitted to an Me 109, G-6 or otherwise, is also unclear.
The Messerschmitt report I have on it, 'Lagerbericht Me 109 Ausblaseversuchstrager (Stand vom 14.2.44)' goes through the technicalities and the progress being made by each firm but doesn't mention what it was all actually for.

 

[TomcatViP]

I am only commenting the drawing in French posted by Newsdeskdan, not the entire 109S archives you mention.

But please note:

"Intrados" implies that the slots where situated under the wing. This would be pointless for the blown flap application as known today.

 

[newsdeskdan]

I am only commenting the drawing in French posted by Newsdeskdan, not the entire 109S archives you mention.

But please note:

"Intrados" implies that the slots where situated under the wing. This would be pointless for the blown flap application as known today.

Okay, I've worked this out. The drawing refers to the openings in the underside of the wing where the undercarriage would have retracted, had it not been fixed and non-retractable, rather than the positioning of the air-blowing slots. The 'S' was to be fitted with removable panels so that the openings necessary for a retractable undercarriage could be simulated as required during testing. And the panel that could be removed to access the air channel. The slots appears to have vented into the gap between the wing trailing edge and the flaps/ailerons.

 

[sgeorges4]

Any idea of what this system would look?

 

[TomcatViP]

Yes but mind that according also to the two view diagram posted on pg1 of the wing (109 early wing), again the slots are depicted underside, turning the thing into a quite strange Lifting enhancing device.

 

[sienar]

Yes but mind that according also to the two view diagram posted on pg1 of the wing (109 early wing), again the slots are depicted underside, turning the thing into a quite strange Lifting enhancing device.

The drawing is upside down because that is how it was mounted when testing was being performed. The slot is on the top injecting air over the flap.

 

[Temistocle]

Maybe the forerunner of the 109S project were the two "suction aircraft" AF-1 and AF-2, developed at AVA Gottingen between 1932 and 1943. They comprised a small internal fan to shortening the take-off distance; the second aircraft was a modified Fieseler Storch.
The following paper is the 1950 NACA english translation of a German report dated July 1943, with a lot of information about the two aircraft.
You can see the same pictures in a better format in the following link, a russian translation of the article appeared on Luftfahrt International N.6 (11/12 1974):

AF-2

BTW, the results of these tests were taken by some "researchers" as evidence of the engines developed for the Luftwaffe UFOs...

 

[Temistocle]

I just found there is another thread about the Fieseler boundary layer test aircraft, sorry...
BTW, there is another 1956 document about the "wing-lift augmentation methods" here:

Wing-Lift Augmentation Methods for the Improvement of Low-Speed Performance of High-Speed Aircraft

There is a small paragraph about german WW2 projects, also with a reference to a Bf 109 testbed ("two blowers imbedded in the wings driven by extension shafts from main engine").