Basic Flaps

[Ack-Ack]

Originally posted by Krusty
Note: This is for those with auto-takeoff enabled only, it does this for all bombers (maybe even all planes?) when you use auto take-off. You need to manually retract at some time, as it leaves them down permanently (for some reason).

That's only because the speed of the plane is still below the thresh hold for the auto-retracting flaps to kick in.  


ack-ack

[Ack-Ack]

Originally posted by McDeath
At the risk of being flamed

I agree with Krusty. He is correct.

edit: afaik, yes it's just the heavy bombers that that start with flaps down

A-20 starts with one notch of flaps deployed and it's not a heavy bomber...


ack-ack

[Krusty]

Ack-Ack, the climb speed for auto takeoff is around 130 mph or somewhere under 150... It won't ever reach the speed where the flaps auto-retract by themselves, as long as you're in auto takeoff. Thus, you need to manually retract them.

[McDeath]

Never flew the A-20, hence the afaik.

[Ack-Ack]

Originally posted by Krusty
Ack-Ack, the climb speed for auto takeoff is around 130 mph or somewhere under 150... It won't ever reach the speed where the flaps auto-retract by themselves, as long as you're in auto takeoff. Thus, you need to manually retract them.

I didn't say it wasn't, I just stated the reason why you need to manually retract them.  


ack-ack

[Benny Moore]

Originally posted by Blooz
Don't use them for takeoff?  Terrible advice.  Takeoffs and landings are the time you want to use flaps.  The heavier you are at takeoff the more flap you should drop to compensate.

Originally posted by Benny Moore
Real pilots only use flaps on takeoff if the runway is short or they must clear an obstacle.

I've never used flaps on takeoff, except when trying to launch a heavy Corsair from a carrier.  Why?  As I said in my previous post, it's quite inefficient.  What's more, that's what they taught me in ground school, and that's how my flight instructor had me do it.  Ask any real pilot who isn't a carrier pilot, and he'll tell you no flaps.

[Blooz]

I guess there would be a difference between an RV8 and a fully loaded P47.

Just because you can take off without flaps doesn't mean it's right.

I'm just trying to help the new guys get off the ground and telling them not to use their flaps is just wrong.

[Benny Moore]

How many times do I have to say it?  Real pilots only do it if the runway's too short or they have to clear an obstacle.  If you find taking off difficult, by all means use flaps.  But don't complain to me when you find yourself being left in the propwash of people like me who, like real pilots, don't ordinarily use them.  And you will be left in the propwash.  Flaps are energy inefficient, period.  And yes, I learned how to take off just fine without flaps, both in reality and in simulators.

And Krusty's right, no one should be taking a loaded ship while trying to learn.  They don't teach people to fly in fully loaded airplanes.  I've had my say, now the new guy can take my advice or leave it.  I really don't care.

[Traveler]

Originally posted by Blooz
I guess there would be a difference between an RV8 and a fully loaded P47.

Just because you can take off without flaps doesn't mean it's right.

I'm just trying to help the new guys get off the ground and telling them not to use their flaps is just wrong.

All of the runways in AH were extended at some point.  There is enough runway to get any aircraft up without flaps.  If departing mid field  you may need to do a short field take off which would involve flaps.   Without a flight manual to give you recommended flap settings for the aircraft, it appears any fighter Aircraft in AH  that the first notch of flaps provides the most benefit of adding lift without adding a great deal of drag,  (that appears to be a sore spot with the aircraft data models).

As for flaps for landing.  Most of the arenas with no-wind, full flaps would be the best approach, however,   If you are two miles from the end of the run way and low and slow, putting in two more notches of flaps should be the last thing you are thinking about.  

 The sole purpose of flaps on an aircraft that is landing is to allow the pilot to increase the angel of decent, without increasing his airspeed.

One more time. The sole purpose of flaps on an aircraft that is landing is to allow the pilot to increase the angel of decent, without increasing his airspeed.  

In other words, push the stick forward to decend without speeding up.  How many notices of flaps that requires to maintain the desired approach speed is dependent on the altitude that needs to be reduced and the distance remaining between the aircraft approaching and the touch down point on the runway and the speed of the wind over the runway.

The Flight manual for the P38J recommends that for Takeoff from a flat dry hard surface of 2500 feet or greater with zero wind across the runway.  That 0% of flaps be used.  this allows for better engine cooling.  Also another part of the aircraft model that is poor in AH.

[Blooz]

I'm not interested in your exploits.

Cessna's rarely take off with tons of bombs, rockets and fuel.

I'm trying to give the new guys a leg up on how to use their flaps to stay out of the trees and water.

To tell them not to use their flaps is not good info.

[BaldEagl]

Edited from aerospaceweb.org:

Following is the lift equation where L= lift force, p = air density, Vsq = aircraft velocity squared, Sref = wing area and CL = Coefficient of lift:

L= ½ p Vsq Sref CL

Of interest to us in this case are the variables
•   L = lift
•   V = velocity
•   C L = lift coefficient
Flaps are mounted on the wings and deflect downwards to generate additional lift. We see this effect in the lift equation through the lift coefficient--as the angle of flap deflection increases, the value of C L increases and the lift increases (assuming all other variables are constant). The amount of lift a plane needs at any given time is directly related to its weight at that time so it is understandable that you might expect the flaps to be set at a greater angle of deflection when the plane is heavier and fully loaded with fuel at takeoff than when most of that fuel is gone and the plane is much lighter at landing.
However, the above discussion assumes that all the other variables are constant at takeoff and landing, and this is not the case. The key parameter we also need to consider is the aircraft's speed. Most aircraft takeoff at a speed that is about 20% to 30% faster than the landing speed. Since the lift varies linearly with the lift coefficient but with the square of the velocity, the velocity has a much greater impact on the lift equation. As a result, we need more flap deflection at landing than at takeoff to compensate for the reduced speed even though the aircraft is lighter. In fact, the primary purpose for adding flaps to aircraft wings in the first place was to reduce landing speeds and give pilots more margin for error in this most critical stage of flight.

----------------------------------------------------------------------------------------------

Please note from the above “the velocity has a much greater impact on the lift equation”.  The exceptions to this would be in situations where sufficient velocity cannot be gained due to factors such as length of airfield or abnormal take-off weight, in which case adding flaps (i.e. coefficient of lift) would allow for take-off at lower speeds.

[Yarbles]

Originally posted by Krusty
When you're still learning (and I assume you are, by this question),

So you know everything right.

[Yarbles]

Sorry Krusty I couldn't resist that, but I think there is a valid point there somewhere.

Here is my question though.

I thought that the surface area on top of a wing is greater by virtue of the shape and therefore the air flow is faster over  the top of the wing and the air pressure is therefore reduced. Lower pressure on top of the wing ='s lift.

Do flaps infact when lowered below fully up increase this lift further but at the expense of increasing drag?

Is that what flaps are all about in which case I can understand why a plane would turn in a shorter radius with flaps lowered so to speak.

I think when new to flying properly grasping the principles or to put it another way the forces involved could be helpfull. Intuitively I see lowerered flaps as increasing the speed of air under the wing and reducing lift. I get this idea from the ailerons which dip on the wing that is dipping and rise on the wing that is rising. Can someone confirm that this is not what is going on.

I would appreciate a first principles explanation if anyone has the time.

[Benny Moore]

First of all, none of us are a really good source.  Check out the Federal Aviation Administration on Google; they should have very good information.  I commend you on your research.  A lot of folks come in here without any prior knowledge of flight, and demand to know why they aren't doing well.  Feel free to stop by the free multiplayer server Blue Sky: Maximum Realism.  You're more than welcome.

[Krusty]

Originally posted by Yarbles
Sorry Krusty I couldn't resist that,

Please do. I get enough sociopathic watermelon from 3 specific people on the forums as it is. They follow me around and reply to whatever I say with crap like that. I don't know if you're just joking or if I should make that "4" now...


EDIT: I just noticed something in your reply. I posted my original reply with all intent to be helpful. Was it not received as so?