Any experience with Spoiled flaps?

[No Step]

Hi all, anyone have experience with spoiled flaps? I don't know what they are really called,.... it's what I call them. I remember seeing them on a fun flier years ago, but have not seen them since.

I'm looking to install them on a Sig LT-25 to give me rediculously steep decents to landing. We have trees real close to the threashold of our runway and I want to come in high and drop fast to landing. I have flaps installed now but so far, not really getting the results I want (I only have a few landings on the flap mod., so maybe I need to play with the setup more. I'm thinking it's the thick flat bottom airfoil fighting the steep decent. I have flaps on two other models that give fantastic smooth, steep decents (but again they are much thinner airfoils). Maybe I need to crank in even more down elev. mix.

Anyway, I remembered this setup and was wondering if anyone has input as to how effective they are? or are they too effective. They look like they'd drop you outta the sky like a rock. Thanks

Fred
https://home.comcast.net/~guilfoyle72/

[Sparky Paul]

Dan Garrabrant has a Senior Kadet with that style of flap.
I've flown it, it doesn't do anything weird.

[No Step]

Do you happen to remember if it provided a steep decent?

Next time I go flying, I'm going to attach a ply plate to my flaps and give it a try.

[biber]

On the H 206 'Hornet' fullsize glider that kind of flaps allow a very steep approach and even seem to lower the stallspeed a bit.

biber

[rebell]

I fly a constant cord symmetrical wing plane with flaperons 20% of the cord, full length. I decent very steep and lower the flaps to 55 degrees down. Its like ABS brakes on a car. Close to the ground I level out and pull up the flaps as the speed will then drop to below stall speed if not careful. It works real good and is a lot of fun. Be careful as you loose aileron control with flaperons fully down. I mixed in a lot of rudder together with ailerons with flaps down.

[Sparky Paul]

They do does steepen the approach.
And you need a bit of power to keep the speed up.

[No Step]

Thanks all for your replies.

[INewton]

I stay away from flaperons entirely because of all the unintended consequences. That is, they do something good, but always do something else that's very bad.

But the spoiled-flap or even better slat flaps where there's airflow over and under the spoiled-flap (like on airliners) are great for those planes (like hotliners) with symmetric wings and moderate wing loading that just keep floating and floating and floating.

As slat flaps are applied, the stall speed keeps coming down and down with nicely increasing drag. And all that without worry of tip stalls since the angle of attack of the entire wing is lowered! These flaps, however, can not be used for for takeoffs because of the excessive drag when applied.

[Prop Spinner]

I agree. You really need to know how to fly before using flaperons. :D

It is a matter if employing and extracting it at the right time. You need to know exactly what your plane is doing at all times. You cannot employ and forget about them. Use it correctly, and it is a joy. ;)

[INewton]

I agree. You really need to know how to fly before using flaperons. :D

It is a matter if employing and extracting it at the right time. You need to know exactly what your plane is doing at all times. You cannot employ and forget about them. Use it correctly, and it is a joy. ;)

There is one type of plane that I actually do use flaperons on, and that's on my 3D tail tappers. The flaperon is needed for elevators!

[avianaut]

I used to fly a World Models Super Stunts. It's a floater too, and picks up good speed on steep approaches. I modified it to have half span flaps, and tried using the flaps in the normal way, not very effective. So I tried using the flaps as spoilers, and as spoilerons, both ways not effective. Next I mixed flaps and ailerons to give a crow setting, better but still not good for steep, slow approaches.

The solution? Before reaching the threshold and at idle I pull up gently untill I can see and feel the stall, then relax the elevator just enough to stop porpoising. The plane enters a steep and very slow descent on the point of a stall and can be steered using rudder only, not ailerons. Just before contact a slight increase of throttle to grease it in, stops in just a few lengths of the plane. Easier to master than it sounds and I could spot land it on call, great technique for small, tight fields.

Just don't try it on a tip-staller!

Cheers.

[Sparky Paul]

Yes, it's rudder-rudder-rudder in slow flight!
Stay off those ailerons! :)

[Jimmbbo]

Anyway, I remembered this setup and was wondering if anyone has input as to how effective they are? or are they too effective. They look like they'd drop you outta the sky like a rock. Thanks

Fred

Fred,

Hmm... Effectively this is a dive brake vs a flap and spoiler, because the flow over the flap will be separated at the spoiler leading edge for almost any deflection, making the flap ineffective for increasing lift... Reckon it will surely work to control descent angle, sorta like an SBD dive bombing the Hiryu ;)

Getting the proper spoiler chord length is gonna be the challenge... might set up your installation to be able to vary the chord of the spoiler side of the rig (maybe make a box in the wing that allows you to make different portions of the "lid" fixed to the wing or part of the spoiler. Interested to see what you come up with.

Cheers!

Jim

[No Step]

I ended up giving standard flaps one more try. This time I just mixed in way more down elevator. It drops in for a nice steep approach. Now, I like landing this plane in our tight landing strip. And even more fun watching guys without flaps try to "make the runway" :).