Flaps question.

[Rod B.]

Can flaps be used to advantage alone, for slowing flight speed, without the support of ailerons?

Secondly, just how much pitch-up is produced when flaps are deployed without compensating elevator mixing? Is it unmanageable?

Thanks,
Rod B.

[Ollie]

Ninety degree flaps will produce similar flight characteristics to aproximately 60 degree flaps and roughly 15 degree aileron crow except the crow will require a lot less elevator compensation. Flaps alone can work almost as well as crow in slowing the model but, require extreme elevator compensation.

If you deploy the flaps very slowly you may be able to keep pitch trim by manual elevator compensation but it will require practise to do it well. I think very few pilots would be able to elevator compensate for sudden 90 degree flap deployment without a serious stall. Try it out at a safe altitude (at least 100 feet) and form your own opinion. Be sure your elevator is capable of plenty of throw. Hi rates come in handy for this.

[BMatthews]

Yes

My Bird of Time works just fine as do many other REF models that I've seen fly.

Pitch up depends to a large degree on the flying speed. At higher speeds it's a lot and needs some down elevator to avoid pitching up into a stall. But at low speeds I've found on the two models that I used flaps on that if you let the speed bleed down to the trim speed then.... surprise, surprise... the model actually trims back to level flight but at a MUCH lower airspeed. But it's a pain to manage.

Do you need elevator compensation mixed in? It depends on whether you're flying contests or not. For sport flying I'd say it would be easy to get away without it. I flew my BoT in contests with no compensation before I got a mixing TX and managed. But then I'm in no danger of winning trophies either.... :D

For sport flying I'd say you can do without it and just learn to lean on the elevator. The best method then becomes to practice at altitude to smoothly extend the flaps and compensate the elevator and, MORE IMPORTANTLY, learn to bring the flaps back up WHILE YOU EASE OFF THE DOWN STICK. Failure to do this last bit will have obvious consequences during landings as you can well imagine.

[Jack Hyde]

Some fliers have been using less aileron rise in their crow mix lately to increase the effectiveness of roll control on landing. I have used flaps with the ailerons neutral and it works - no out of control feeling.
It is possible to use flaps without elevator mix but it isn't much fun. If you don't apply down elevator by moving the stick the plane will almost certainly stall just where you don't want it. You can try it at 100' and see how you like it. I have accidently switched off the EL mix and landed ok but didn't like it.

[R. Carver]

Originally posted by Jack Hyde
Some fliers have been using less aileron rise in their crow mix lately to increase the effectiveness of roll control on landing. I have used flaps with the ailerons neutral and it works - no out of control feeling.


Most of the contest fliers around here don't use ANY up aileron! Interesting how trends vary from one part of the country to another :)

Ditto what Jack said about elevator compensation...you can do it manually, but it ain't fun!

[Rifleman]

First time on this forum guys so forgive me if I sound like I am behind.........all this talk of flaps has me full of lift, but its not really a drag....okok OK ..corny.....I flew a Sagitta 900 with a slight kit bash....went for the central dihedral only and put aside any poly except for the last rib bay....I used a piece of trailing egde stock in between two ribs to turn up the tips only a little....then for the balance of the trailing edge I divided it 50-50 and made 25% chord flaps and ailerons.......flaps had 90 deg of motion and ailerons were 3:1 differential, moving upwards around 35-40 deg....this is just to let you know about the flap effect on the config I was flying.....when deploying flap incrementally at high speed, there was a pronounced increase in lift which had to be flown out on the transmitter as well as a mix I had in, to compensate with down elevator. Once the speed stabilized, I could find myself in a 45-60 deg dive without building too much speed once I had full flap. This should go without saying, as there are many flight regimes to deal with and the most critical of all is one where you have an excess of energy to bleed off.....if you want to lose height, I think its always a good idea to get rid of speed first if you are making an approach, then once stabilized you can do what you need, to make a run at the tape for bonus. I never had a huge bother in flying my stab to contain my attitude when bringing in flap, after all, thats why we all fly R/C, ...so we can fly it ! Lets not forget this and rely on the radio to do things for us that we can learn to deal with for ourselves.......
I also had a regular Sagitta at the same time and both were very enjoyable but in different ways.....RES has its day and full four servo wing has its day too, just depends on how you feel like flying at any given time........I flew with the COGG in case any of you wondered where I did my time.