Flaps deployment

I was talking to 2 different P-51 pilots recently about the P-51s flaps. I described how they work in DCS. IE: if your going to fast, the flaps wont deploy past the safe speed. I was told by both flat out that this is not accurate. They stated that the P-51 will deploy flaps at any speed and its up for the pilot to keep from breaking the plane or exceeding the limit. What gives on this? Im not expecting a performance gain, but it seems odd that in a game like DCS you'd have such an artificial limiter. In addition, this makes the 109 flaps seem rather odd to me. For one, in direct contradiction to the manual, I can open my flaps fully at ANY speed. Yesterday I was doing it at 440mph, then diving from 20,000ft to the deck at over 400mph and pulling out leaving the flaps at full extension and nothing detrimental happened. I find two things odd about this. Firstly, it seems like there should be some kind of detrimental effect from deploying max flaps at nearly 3 times max flap limit. Second, I find it kind of hard to believe that someone could hand wheel out those flaps at that degree at that speed.....when at least according to DCS, a plane with a 1000+psi system cant.

Sorry if this seems like a two plane problem. Wasn't sure where to put it.

Great find and a funny one at that. :P What about 190?

Great find and a funny one at that. :P What about 190?

not tested but Id imagine the same.

They stated that the P-51 will deploy flaps at any speed and its up for the pilot to keep from breaking the plane or exceeding the limit.

That is very true.

In reality, if you break the flap not only can the asymmetrical lift kill you, it is a very expensive repair.

If you are flying for pay, you are unemployed at that point....

So how often do you think pilot ignore flap deployment speeds?

Right, they do not. So what is more realistic?

Realistically forcing you to behave like a real pilot or having a bunch completely unrealistic behavior in the sim?

Hydraulic actuated flaps, if they designed properly, will stop if the hinge moment is greater than the actuator force. It's very common for hydraulic actuator, sometimes the whole velocity vs force curve is listed (generally it's a kind of parabola) or two numbers listed for free moving velocity and for stopping force.

 

So you can try to deploy flaps at high speed... if one payed attention to the flaps they would see that at high speed the flaps are depolyed only partly, even if the selector is in 45 position.

I have discusses this issue at great length with multiple P-51 pilots. The flaps on the P-51 WILL deploy at speeds over the allowed amount. If this were changed I dont envision some advantage, but rather that pilots would have to pay attention and have more discipline to not break something.

That is very true.

 

In reality, if you break the flap not only can the asymmetrical lift kill you, it is a very expensive repair.

 

If you are flying for pay, you are unemployed at that point....

 

So how often do you think pilot ignore flap deployment speeds?

 

Right, they do not. So what is more realistic?

 

Realistically forcing you to behave like a real pilot or having a bunch completely unrealistic behavior in the sim?

Well then, I guess all planes should just be ai controlled so as to prevent any non-procedural mistakes. Such brilliance....:doh:

So these P-51 pilots have deployed their flaps at speeds over the allowed amounts before?

That would appear to be obvious.

A direct quote:

"The flaps will come out based in HYD pressure and flap handle position. Nothing else. Put the flap handle at the third notch at 450 MPH and you risk structural damage. There is no built in limit other than the pilot."

I will give a name for this pilot as soon as I have contacted him and have permission to give it.

And Another:

part of my original question:but in sims the P-51s flaps refuse to come out farther than the amount allowed for a given speed even if I put the flaps controls down to the bottom. If this is indeed accurate behavior, is it limited because some kind of safety is preventing it, or because there is insufficient hydraulic pressure to make it happen?

(in response to a question I had about the plane)XXXXX: The real 51 flaps come out "RIGHT NOW!!!!!!" Your game, and I emphasize GAME, having nothing to do with 1400 lbs PSI in REAL life, has nothing to do with reality. No! Nothing in your GAME as described is accurate!

Starkey So they come out at any speed? Even if over prescribed limit? That is very interesting.

XXXX: Yes! And you may break them if deployed to fast!

So the answer is no he hasnt. if I understand what Yo-Yo is saying is that depending on the speed and forces involved, your handle might be in full down position, but the forces wouldnt allow them to move completely to full down... there is no physical stops, just the system isnt strong enough to open against the forces against it...

 

Remember, Yo-Yo has P-51 pilots in his phone book as well, its possible this has come up before...

Ill spell it out. Either he has done it himself, or someone who taught him to fly did it. I dont know. But you have obviously made up you mind in favor of your benefactors so......:music_whistling:

Your pilot friend sounds quite angry too...

He was not.

He was not angry. And Im not certain why that needed commented on.

Anyone got the time to actually work out the forces involved at various airspeeds to deploy flaps vs force available to do so?

Can't argue with physics ;)

The pilot has given permission to quote his name. Chris Fahey.

He also gave me this to say:

"They will go down over limit, with 1200 lbs of pressure or so, and to much over limits and you will damage the flaps, or structure. There is no blow up in the Mustang, or limit other than position of the flap handle and the pilots brain."

Additionally: He states these pilot can confirm this as well: John Muszala, Scooter Yoak, Rich Palmer will all confirm this.

Did you ask him if he did it?

He states: No. I've never over sped the flaps in the 51. I don't want to fix them. but I've flown, built, serviced, overhauled the Hyd actuators to know.

s a side note, I find it hard to believe a pilot would try something like this (Maybe back during WWII, but not these days), if the possibility for damaging the plane is at risk, so no, its not obvious to me that anyone you talked to has tried this...

Right Sithspawn!!

If you overspeed the flaps in the real world, at a minimum the mechanics will remove the flaps and do a dye penetrant inspection of the hinges and attachment points for damage.

Yo-Yo is right, some flap designs will help the pilot if he makes a mistake or hits a gusting situation that causes overspeed. Even those systems do not prevent tracks, hinges, supports, and even flap surfaces from getting bent all the time.

Many systems have no protection and folks have died as a result of flap failure.

23 August 2000; Gulf Air A320-200; Near Manama, Bahrain: The aircraft was making at least a second attempt to land at the Bahrain International Airport after a flight from Cairo when the aircraft crashed into the sea about three miles (4.8 km) from the airport. The aircraft was executing a missed approach and descended into the sea shortly after the crew received warnings associated with a flap overspeed condition. All eight crew members and 135 passengers were killed.

An overspeed inspection must be performed anytime the airplane has exceeded one or both of the following:

- Airplane overspeed exceeding placard speed limits of flaps.

- Airplane overspeed exceeding design speeds.

http://www.inetefb.com/Documentation/Cirrus/AMM/pdf/5-50.pdf

To know what? That they will open no matter the speed? How can he know that if he hasnt tried it, when it makes more sense that if there is more force acting against them, than what is used to open them, they will probably stop?

He states: The slip stream or air load won't keep the flaps from going out. Though if you are at 500 and go flaps 50 or full, they may just we'll break, bend, break the actuating Rod etc before they get all the way out.