ok given a plane trimmed for straight and level flight, what would be the expected result of applying 1/4"deflection of flaps?

I have so far recieved to differant responses and reasons

1. would go nose up because of the increase oflift

2. would go nose down because of drag and increase of undercamber of the airfoil


and would the same effect be expected if the deflection was increased to 1/2"

It depends on the plane. Some planes will remain fairly level, and some planes will balloon up a little bit and climb when you apply the flaps. It can also depend on other things such as the speed of the plane when you apply the flaps as well. However, it's is extremely unlikely to nose down the plane. To understand this you have to understand the aerodynamic effect of flaps, and what they do when deployed. The curvature of the top of a wing causes lift as air flows over the curve (very simplistic explanation, but you get the idea). When flaps are dropped it has the effect  of extending the back of the wing and increasing the surface of the curvature on the top of the wing. Because of this the wing can produce the same amount, or more lift at any given airspeed. This will allow the plane to continue flying at slower speeds, which can allow it to land at slower speeds (one of the two times flaps are used). The other time flaps are used is on takeoff. The effect of the flaps increased the lift on the wing which allows it to get off the ground quicker, especially when it's heavier at takeoff. This effect is why most (but not all) planes usually balloon up when you apply flaps. When you drop the flaps the wings is now producing more lift at the same speed, which caused it to rise up.

Ken

As stated by RCKen generally true but have also seen opposite occur. Besides 1/4 inch deflection is almost negligable. Easy to find out just take it up, reduce throttle to idle and give it a try. Nothing that you can't correct will happen. once determined you can then mix some corection in elevator, when flaps are deployed. If desired.

Thanks RCKen, that would have been my guess, although i have as noted above ,have a few state the reverse,
Being a retread so to speak , been out of RC since 98 ( 2m gliders ) and out of powered RC since 76 i did have to relearn a lot, especially coming back from Gliders ( but this helped)was able to solo out after 4 flights with an instructor, The Plane in question is the T-34 ePTS wth Wing Droops, Flaps where set up to be operational. Now the instructor never bothered with the flaps so i have learned this plane with Flaps up. and generally fly @approx 1/2 throttle.

Just practicing straight and level flight in and out of the pattern right now, which was when i first tried dropping the flaps.

Now thePlane i purchesed from another club member so all the settings where progrmmed into the DX-7 ahead of me.The Nose downattitude i have observedfrom this plane is due tothe programming ( i assume ) as it isset to a value of 80 down with full faps but was set to 23 up at half flaps.
Howeverishould also note it was initialy tail heavywhenI trimmed i out.

I have began altering the settingsas i become more comfortablewith it ( only around 4 flights on my own so far ).

There is one other major Item to keep in mind. Flaps also increase drag as much as they do lift. 10 to 15 degrees of flap seem to produce the best lift to drag coefficient. The higher degrees of flap used the higher the drag, the lower the increase of lift. the use of full Flaps is to help in landing your plane at a steeper angle of attack with out gaining air speed. For an example say you had a very tall tree at the end of your runway. With out flaps at the steeper angle of attack needed to land you would over shoot or end up in the grass at the other end of the runway. With Full Flaps deployed while coming in for the landing at the same high angle of attack needed to land on the runway can be accomplished by the drag caused by the flaps and little to no increase in air speed.
jerrysu29 Call Sign Wild Man

ok well thanks Jerry , Ted & Ken , some great answers there, headed out shortly here, so i will put it about 2 crashes high, and deploy flaps again. Based on the above posts, for the initial setting i have removed the Elevator mix value for the first setting(the up mix ) and reduced the down elev value for full flaps by 3/4's ( dn 15 ).

should be nice to see how slow this thing does land / fly. supposed to be way slow with full flaps.

by the time i get used to all this, it will be time to remove the droops lol.

BTW anyone have any experience with the ePTS stuff, the last thing they recommend is removing the droops, but dont really say when.. ie full flaps to half flaps when your comfortable with take off's, No flaps about the time your ready to land and solo. but they never talk about the droops. Just a case of when ever you feel comfortable? or Know how to avoid or recognize approching stall etc.....

One more caveat about flaps:

Do not retract flaps to normal flying position until the model reaches the speed that will sustain flight with no flaps.
If not, the model will just drop because it is flying too slowly for no-flaps conditions.

Flaps increase the chamber of the wings and their pitch down tendency, as well as the down flow that leaves the trailing edge.
The angle at which that down flow strikes the horizontal tail will determine if the model will pitch up or down when flaps are deployed.

Regarding the droops:

Their function is to eliminate tip stalls, which will be followed by a sudden and unwelcome roll.
Especially for tapered wings, the stall tends to start at the tips.
That may be desirable for a model that needs to be agile in roll, but not for a trainer.

The concept behind the removable droops is progressive training and agility.
It is up to your confidence to decide when they can be removed.