Author Topic: Question about Flaps Deployed at High Speeds.. (Read 2345 times)

crowbaby · « **Reply #30 on:** January 04, 2003, 08:02:37 AM »

Sorry, can't figure adding more than one pic at a time.
This is cut and pasted from the Hurricane manual:

crowbaby · « **Reply #31 on:** January 04, 2003, 08:04:25 AM »

This is typical of all Spitfire manuals that i have:

crowbaby · « **Reply #32 on:** January 04, 2003, 08:09:11 AM »

This is from the Typhoon manual.

The Tempest says the same, except:
max speed with flaps down is 160mph, and 210mph at 20 degrees flaps
Changes of trim -
Flaps up: Initially nose down, finally nose up
Flaps down: Nose down (During the first 20 degrees of flap movement the change of trim is marked)

crowbaby · « **Reply #33 on:** January 04, 2003, 08:14:32 AM »

And our Mosquito Mk VI

crowbaby · « **Reply #34 on:** January 04, 2003, 08:22:08 AM »

More info on the Mosquito, it occurs to me that this is at least as relevant as the actual flap settings. If anyone's interested i can dig out max flap speeds, etc. for the others, and look for flap settings and limits on other planes, but i don't want to clutter up this topic unless there's a demand?

ramzey · « **Reply #35 on:** January 04, 2003, 08:39:39 AM »

im sure most of u know that place, but to reminde u all:)

http://www.zenoswarbirdvideos.com/main.html

F4UDOA · « **Reply #36 on:** January 04, 2003, 01:17:44 PM »

Dtango,

If you check the P-38, P-51B/D, F6F and F4U full flap stall speeds at the loading used in the manual you will find that they are all off. Some of them are off with no flap set so it may not be just the flaps that are set wrong.

I tested this at one point although I do not have the results in front of me using the digital speed read out I found the stalls were significantly further off with flaps than without.

For instance in the F6F and F4U manuals they list the stall speeds at the weights of 11,250LBS for the F6F and 11,300LBS for the F4U engine on at idle as reccomended in the manual. I take the fuel load that leaves me with the weight as close as possible and hold the nose level until stall. You can choose not to hold the nose steady but it will only adjust the stall by a few MPH and I am not talking about a few MPH.

The Flight manual stall for the F6F is approx. 74MPH in the clean condition!!! The AH F6F cannot fly even close to that slow speed. In the full flaps position from the manual stall speed is listed at 50Knots however the CAS correction table adds about 6.5knots to the speed with 80Knots indicated so I'm guessing that the full flaps stall is around 65MPH. Without flaps the CAS correction chart actually reflects a slower speed than indicated!

The F4U is also subject to the same. Power on stall 11,300lbs should be 84knots in the clean condition or 97MPH and full flap stall is at 66 knots or 76MPH which is about 15MPH slower than AH allows. The CAS correction chart acctually shows a reduction in speed at stall in both conditions of about 2 to 3 Knots.

This explains to a great degree why it is so hard to get a F4U off the carrier deck. The stall is simply too high for liftoff.

The P-38 manual shows a power off stall clean of 100MPH and full flaps at 76MPH. The CAS correction chart does bring those numbers up showing a correct speed of 100MPH when 83MPH is indicated in the clean condition and 89MPH with full flaps. So stall is harder to calculate.

The P-51D 9,000LBS shows stalls of 101MPH and 94MPH respectively power off. These numbers would come down about 5MPH with power. Again I think they are just to high.

Anyway I know AH can't expect to be perfect but sometimes I think parity is the goal and not accuracy.

F4UDOA · « **Reply #37 on:** January 04, 2003, 01:36:43 PM »

JAB,

I have known about the F6F flap situation for quite some time. The reason I haven't said anything is this.

It is allot easier to get an A/C porked in here than to get one fixed. For instance the F6F should stall about 76MPH with no flaps. So if I complain about both which one do you think will get fixed first? I don't wan't to be the guy who "porked" the F6F.

For all of the posting I have done on the F4U I have never really had anything fixed. The F4U-1D is different than it was but HTC made the C hog heavier, modeled the -1D with drag from external stores regardless of loadout that slows it about 10MPH and the F4U-4 still climbs about 400FPM to slow all with data I have provided. They ignore the positive and change the negative. And the funny thing is that I think the C-Hog data is wrong. I think it should be much lighter than it is and I have data to prove it.

So what have I really done except run my mouth and pork the A/C I'm trying to fix.

So I'm going to relax on this until I can get 5 minutes to talk to HT or Pyro. I whish they hadn't killed that Q&A forum so fast.

dtango · « **Reply #38 on:** January 05, 2003, 12:00:08 AM »

F4UDOA:

I have clean CLmax for the F6F-5 listed at 1.41. Using this figure at ~11,300 lbs weight stall speed should be ~96-97MPH.

If I run the calcs backwards using a stall speed of 74MPH I get a CLmax of a whopping 2.41.

Flight testing in AH taking the F6F-5 with 25% fuel which gives me a ~11,300 lbs of weight I seem to get a stall at ~97MPH. CLmax calculations give me about 1.40 which seems to be in line with the CLmax figures quoted for the F6F-5.

Tango, XO
412th FS Braunco Mustangs

Toad · « **Reply #39 on:** January 05, 2003, 12:11:22 AM »

OK, Tango.. 'fess up. This stuff is a bit more than a hobby with you isn't it?

dtango · « **Reply #40 on:** January 05, 2003, 12:36:27 AM »

LOL Toad

. What was it that you said? Something about being a bit too esoteric??

Hey, I need something to do in between the times my 2 year old gets up every 5-10 min trying to find a way to avoid bedtime when it's time for him to go to bed!

Tango, XO
412th FS Braunco Mustangs

Toad · « **Reply #41 on:** January 05, 2003, 12:43:38 AM »

Somehow I get the feeling you are intimately familiar with Bernoulli and Ernst Mach and all the rest of those guys.

I bet you even know what Keuffel and Esser made.

dtango · « **Reply #42 on:** January 05, 2003, 12:56:30 AM »

LOL! Bernoulli and Mach - yeah I think those guys are more like the crowd funked hangs out with

.

Keuffel & Esser! LOL! Now that is truly "classic"! Them things were before my time thank God! Of course I always envied the guys and gals that got to use Mathcad for calculus! Man, what happened to old fashioned pencil and paper slaving away to integrate something???

Tango, XO
412th FS Braunco Mustangs

Badboy · « **Reply #43 on:** January 05, 2003, 06:33:28 PM »

Quote

Originally posted by dtango
Hey, I need something to do in between the times my 2 year old gets up every 5-10 min trying to find a way to avoid bedtime when it's time for him to go to bed!

Hey, that's exactly how I got my callsign

Badboy

dtango · « **Reply #44 on:** January 05, 2003, 10:14:23 PM »

Hehe Badboy - I'm confused though! So were you the parent trying to put the youngster to bed or were you the youngster trying to avoid bedtime? Or were you the parent that was paying your youngster to avoid bedtime as an excuse to stay up later!

Tango, XO
412th FS Braunco Mustangs