Question about Flaps Deployed at High Speeds..

[Toad]

That's part of the problem with this airplane stuff. To every generalization, there's an exception.

Some of the newer Boeings have a "blow up" feature from the last notch of flaps to the next to last if you overspeed at full flaps.

[whgates3]

ja, the modern airliner solution seems probably a bit advanced for AH planes, except maybe the 262 (which most modern airliners seen to be based around)

[F4UDOA]

Part of the problem with the flap modelling question is that it is a bottomless topic. There are many variables in how the flaps worked at all in AH that are not modelled.

For instance.

The F6F had electric flaps. As far as I know they were only two position either half or full deflection with is not modeled here and they were also much slower to extend and retract than hydrolic flaps. But they were in fact real "Blow up" flaps as modelled in AH.

The F4U had 5 position hydrolic flaps but were also "blow up" flaps which would redeploy after speed was lost. Also it had an "overload release mechanism" which would protect against use at excess speeds. In addition there was a "combat flap" setting of 20 degrees which could be used up to 200knots.

So basically there are many pieces of the flap puzzle to solve before you can address one feature.

[F4UDOA]

Just checked my F6F flight manual.

1. They were electronically controlled but actuated by 4 hydrolic pumps.

2. They were 2 postion flaps. Full up or full down.

3. The manual states they were low drag flaps whatever that means.

4. This is what I mean by bottomless subject(and I don't mean with no pants on). The F6F had blow flaps that independant of the Hydraulics and would push the flaps up from 50 degrees at 93knots to 15degrees at 150knots. This feature could not be controlled from the cockpit!! Aslo the flaps cannot be extended at speeds in excess of 170knots.

[leeburt]

460 mph sounds very high as a limit to me.  I cannot recall a real world aircraft that I've flown that has a flap speed anywhere near that high....speed/dive brakes maybe, but not flaps.  In my experience the purpose of flaps are to enhance low speed handling characteristics, and to reduce angle of attack (high nose up) at low speeds (approach to landing).  There's not much logic to their functioning for this purpose at such hig speeds.  

What I relate here applies to general aviation, corporate jet and commercial aircraft types, and not to war birds per se.  But, I cannot envision why they would have incorporated flaps that operate at such high speed into their design either.  Can anybody point out a real world design in which 460 mph flaps (Vfe = 460 kts) exist?
 
Navy49

[J_A_B]

Hey F4UDOA, is that manual from an F6F-3 or an F6F-5?

Also, how did the flaps work?   I'm not too familiar with the interior of the F6F.    I know that, in the P-38 for example, the flap lever only had 3 positions--up, "maneuver" and down--but regardless of that fact you could set the flaps at any setting in between that as well.   OTOH, with a plane like the Spitfire all you could do was up ro duwn since the switch was basically a toggle switch.  

J_A_B

[funkedup]

Originally posted by Toad
That's part of the problem with this airplane stuff. To every generalization, there's an exception.

Some of the newer Boeings have a "blow up" feature from the last notch of flaps to the next to last if you overspeed at full flaps.

That would almost certainly have to be a function of the control system, not a feature of the anti-backdriving mechanism.  I.e. it measures airspeed and commands the flaps up one notch if you overspeed.

Although I'm sure some nerd somewhere could design a load sensitive mechanism that overrides the anti-backdriving only at full flaps position.

[Kweassa]

It'd be helpful if HiTech could give us his opinion.

 I'm not demanding an explanation or an answer here! I don't even have the slightest idea whether AH should change or not!

 I'm just wondering what HiTech feels about this issue. I'm wondering if there's a helpful answer to how he feels about the flap deployment speeds and variables like his explanation on the combat trims which were very helpful and reasonable.

 Despite all the helpful explanations, I'm still very confused and the picture is very unclear how the flaps might react when deployed over suggested limits...  

[F4UDOA]

JAB,

Believe it or not that manual is for both the F6F-3 and F6F-5. It list different restrictions for both varients.

The up/down flap lever is exactly as you describe it in the Spit. Simply a toggle switch. However it does state (maybe like the P-38) that the flaps can be in any variation of settings as they blow up from 50 degrees. You just can't set them that way from the cockpit. I have a P-38 manual as well, I will have to compare the two.

The F4U on the other hand had a 5 position flap lever.

In the 1944 Joint Fighter Conferance book the pilots had some very interesting conversations on flap types including blow up flaps and their use. That book gives you the best idea of what the feelings of the time were about everything from flaps, guns, gun sights, dive flaps etc. They pulled no punches.

I have manual for the

F6F-3/5
F4U-1
P-38F-L
P-47N
P-63

I will compare all of there flap types.

FYI, not to change the subject but our flaps still do not provide enough lift. This can be verified very quickly by checking full flap stalls on the digital readout in the film viewer. They aren't even close.

[dtango]

F4UDOA - what do expect the lift to be?

Tango, XO
412th FS Braunco Mustangs

[J_A_B]

As a slight sidenote to this thread's original intent, perhaps you could scan the pages relating to the F6F flap operation and E-mail it to HTC?  

HTC seems to have info which syggests the F6F had miltu-position flaps...not only does the AH F6F have such flaps, but as you might recall the WarBirds one did too.  If they're mistaken, it's up to us to prove it  

J_A_B

[Toad]

Funk, I probably have the books in the attic but it's abit to esoteric for a stick monkey's interest.  

[funkedup]

Same here on the interest part.  

[dtango]

BTW Kweassa - Andy Bush wrote a nice article on flaps on SimHQ that sheds some more light on it all.  More stuff covered there than the questions asked here but good stuff at any rate.

SimHQ Flaps Article

Tango, XO
412th FS Braunco Mustangs

[crowbaby]

Dug through various documents to find some info about the flaps on our various planes

From eric Schillings notes on the P-40:

8. Wing Flaps - The wing flaps are operated hydraulically by either the hand pump or an electrically operated pump. The selector handle is located on the port side of the cockpit beside the pilot's seat and moves fore and after; - forward for "Down" and after for "Up" and neutral for "Off". The hand operated hydraulic pump (see para. 7) may be worked back and forth to raise or lower the flaps after the up or down position has been selected on the handle. The flaps may be operated manually in order that partial setting may be obtained more easily. With aid loads on the flaps they will close automatically as soon as the selector switch is moved to the "Up" position.

[ES: our flap control lever had a push button on the end which had to be depressed in order to move the flap handle out of the neutral position. When placed in the up position, the little finger was used to turn on the electric hydraulic pump. The same switch was used to acctuate the hydraulic pump both for the Flaps and Gear.]

NOTE: - Flap selector lever cannot be set to "Up" position until undercarriage lever has been returned to neutral. [ES: We did not have this type of flap control.]

Below:from the Mustang handbook (Export P51 for UK):