F4U divebrakes

Re: Just trying to be helpful

Originally posted by Moggy C

I think it might have been sorted out, but I lost the will to live yesterday and left the thread.

Moggy

Still leaves me with the intriguing question as to the symptoms of a stalled pair of wings in a vertical dive.

How about a flat spin? OK, sorry for that. Again, AOA is the key. If you can get the wing cord pointed about 20 degrees or so from your flight path the wing will stall. It doesn’t matter if you’re going straight up or straight down, and it doesn’t matter how fast you’re going.

I can think of several airshow accidents (and you can too) where the pilots “mushed” in from a loop or split S. This is a classic accelerated stall, it just happens to be one traveling towards mother earth.

Looking forward to having that little “chat” next month you promised me.

Cheers,

Steve

The Question was asked did Corsairs have Dive Brakes, I answered no they used their Gear for dive brakes when they were dropping munnitions. This lead to the point were we are now.

As for the Flight Sim. we have one at work that can be program with up to 100 differant types of aircraft(got to love the Military and their toys) so I ask the tech to put in three different ypes of Corsairs the -3,-4 and the AM-1.

Lets say the stall quilatys are verry differant for each and for the -4 are sneaky at best.

Yes the best place to learn and practice stalls are with a certified CFI.

Just trying to be helpful

Somebody asked about the use of the gear as divebrakes on the F4 Corsair. (Fact, supported by the placarding on one of the models)

This was then confused by somebody mentioning stalling whilst delivering ordnance in level flight.

We then had a brief treatise on aerodynamics

I think it might have been sorted out, but I lost the will to live yesterday and left the thread.

Moggy

Still leaves me with the intriguing question as to the symptoms of a stalled pair of wings in a vertical dive.

I’ve read this thread six times and I have absolutely no idea what you guys are talking about. Before you get some student pilot killed let’s remember some facts…

1. You can stall at any speed and any attitude (including going straight down in a vertical dive).

2. Stall speed is a constant variable, because stalls are all about AOA; the angle of attack of the wing relative to it’s path through the air. Pull or push hard enough to point the nose (AOA) away from the direction you’re going, and you will stall. Also, if you’re above maneuvering speed you could over G load and pull the wings off before you stall.

Don’t learn (or relearn) this on the web or from a flight simulator. Get with a qualified CFI and make sure you have a proper understanding of aerodynamics. Go practice accelerated stalls with an instructor (In the L-39 we do them at over 250 kts, 60 degree bank and 4-5 g’s) Knowing this is important. Understanding it will save your life.

BTW, I’ve a very nice chart from the US Navy’s NATOPS Flight Manual left over from my T-28 days that shows the relationship of beginning altitude, airspeed, dive angle and g to recovery altitude. Simple. The faster and steeper you go, the more altitude and g you need to recover. Pull too much? See #2 above.

Now, how did we get hear? Something about gear and stalling speed?

Bingo , Thats it exactly.

I tryed this out tonight on a Flight Sim. at work,six times I ended up with a particle to complete wing stall. All times I ended up Dead.

This is what he explain to me. They would over fly the target get ground troop location call in to GC officer. then they would back off the Man pressure, enter into a shallow dive(mined you they are comming from 2000AGL) at 1500 they would dump the gear allowing them to maintain a consent airspeed without induced wing fluttering. This was done with about 350 to 375 indicated Air.

At the bottom of the dive when they reach 600-550 AGL they would let go of the munnitions and start a hard pull up and turing away from the target, if they did’nt have the gear hanging the Corsair has a nasty habit of mid-wing stall

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I think you are trying to say they had to use the gear to maintain a airspeed between 350 & 375. However if they exceded that airspeed in a hard pull up it would result in a acellerated stall that would progress from the wing root to the tip.

Can’t argue with any of that, but none of it proves that lowering a Corsair undercarriage reduces its stalling speed.

Moggy

I can agree with that! It has nothing to do with stall speed. Just a greater angle of desent without a increase in airspeed.

Talked with a local Corsair pilot here in Denver yesterday at the Wings over the Rockies museum, he flew early birdcage models, dash 4 and 4B’s, and the -5…he liked the Corsair a lot, never had trouble getting it aboard a carrier at all…..I asked him if he’d heard of a Corsair chopping the tail off of a Japanese ‘Sally’ recon plane, he said he did’nt need to hear about it, one of the guys in his squadron chopped the tail off a Twin Beech by accident and still landed the Corsair (the three guys in the Beech were’nt so lucky, they died….the pilot of the Corsair was inspecting the landing gear of the Beech when he got too close and chopped the tail off).
The guy’s name was Don Welsh, a nice gentleman…and he extended his invitation to any Brits who should stop by to see the “Battle of Britain” display at the museum, a very interesting set up as I can testify to it first hand…very well done.

Mark

Hi Guys,

I talked with a Corsair pilot friend of mine who flew closs air during WWII.

This is what he explain to me. They would over fly the target get ground troop location call in to GC officer. then they would back off the Man pressure, enter into a shallow dive(mined you they are comming from 2000AGL) at 1500 they would dump the gear allowing them to maintain a consent airspeed without induced wing fluttering. This was done with about 350 to 375 indicated Air.

At the bottom of the dive when they reach 600-550 AGL they would let go of the munnitions and start a hard pull up and turing away from the target, if they did’nt have the gear hanging the Corsair has a nasty habit of mid-wing stall.

One of the things they decided to try was to install wing stall strips to reduce wing flutter it was marginally sucessfull. It depend on munnitions and angle of attack.

I know this does’nt explain alot, but it helps some what. Also I asked him about Dive Brakes in Corsairs and he told me that they never had them he flew ever type including the AM-1 in Korea and F4U-7s. Their was some attempts in the field to make dive brakes in the lower fusl. area but because of the Corsairs speed they just ripped them apart.

CM didn’t literally say “lowering the undercarriage reduced the stall speed”.

I suspect what happened in that case was the pilots knew how an aircraft would slow down with the UC lowered, as they landed them every flight (with luck ;)). So they were a lot less likely to slow down too much and stall, because they knew how it would handle, the required power settings etc.

Originally posted by Eddie
The funny old thing is that I don’t think anyone ever said it did. Just that it allows you to fly a steeper approach.

Originally posted by crazymainer
Corsair pilots were slowing down to much causing a stall coundition when they drop their tanks. Some pilot came up with the idea of lets try it with the Gear down..

The funny old thing is that I don’t think anyone ever said it did. Just that it allows you to fly a steeper approach.

Can’t argue with any of that, but none of it proves that lowering a Corsair undercarriage reduces its stalling speed.

Moggy

you kind of know what everything does but need to know how it all relates together. When you slip you push a side of the aircraft into the slipstream producnig more drag than lift. This allows you to make a steeper approach without increasing airspeed. I have got to go but as a pilot you really need to reread the chapters on Aerodynamics. and the different types of drag. When I was a CFI I would have to constantly have to reread the manual

Stalls are about angle of attack, not airspeed. When the wing reaches a certain angle of attack, it will stall regardless of the airspeed (it’s possible to stall at 400mph).

If you keep the wing at zero AoA in a dive (it’s possible), the wing won’t stall.

Originally posted by Wrenchbender
Ok, Think about this?

Q, Why do we use Flaps? Why not just slip it in?

Speak for yourself. I slip it in, my PA22 not having flaps

Flaps slow the aircraft down and lower the stall speed in varying degrees depending on the design of those flaps and the amount applied. Pulling a lever is easier than learning to fly properly

As above, they can produce varying quantities of both

[quote] Q, Will using flap allows us to make a steeper or shallower approach? [/QUOTE]

Steeper

Your point is?

Moggy

Correct Mike J. As the Flight manual states a wing can stall at any airspeed at any attitude! Like a accelerated stall.

Ok, Think about this?

Q, Why do we use Flaps? Why not just slip it in?

Q, What is the advantage?

Q, Can Flaps produce more drag than lift?

Q, Will using flap allows us to make a steeper or shallower approach?

Originally posted by Wrenchbender No I’ll stick with my answer. Better get your aviation handbook and read it again. Don’t you have Flight reviews in England? Reread the chapter on flaps and dive brakes. [/B]

Yes, they are both definitely in my books. One adds lift and drag. The other just adds drag. Hence one has an effect on the stalling speed and one doesn’t.

Moggy

WB: You sure you wouldn’t like to reconsider? I’m assuming by ‘angle of dangle’ you mean ‘angle of attack’

The only way you can reduce the stalling speed is by adding lift / reducing weight.

How exactly does adding drag by lowering the gear achieve this. It would seem to me that all the added drag would do is make you reach the (unchanged) stalling speed more quickly.

Am I being particularly dense here?

Remember Lift / Weight / Thrust / Drag?

CM: If by ‘everything’ you start to include flaps, then your argument starts to make sense as these would increase the available lift and enable you to fly more slowly. But the u/c adds no lift, so would be superfluous in this case.

Anyway divebrakes are specifically used to stop an aircraft speeding up in a dive. Here the gear would perform that function, but this has nothing at all to do with stall speed and stalling.

Moggy
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No I’ll stick with my answer. Better get your aviation handbook and read it again. Don’t you have Flight reviews in England? Reread the chapter on flaps and dive brakes.