Although Ican't presently find it, I'm almost certain that I've seen a picture of one of the old classics with a combination flap/spoiler arrangement (one of Hanno's, I suspect). I'm presently building an ultrasport, and am putting flaps on it, and have the crazy idea of combining a spoiler function with the flaps. Basically thinking about using something like 1/32 ply laminated to the dorsal surface of the flap and extending something like 1/2 to 2/3's of the flap cord forward of the flap, and recessing it into the TE. Thinking I could use CF veil or 0.5 oz glass on the underside of the spoiler portion if needed for rigidity. Has anyone tried this? Any ideas on the effect on handling characteristics? I suppose I could get the same effect by simply programming a bit of up reflex into the ailerons to mix with the flaps, but for some reason this idea appeals to me.

Bob

i think it was the MK Magic?

Acutally it was the curare, the initial one. Later versions of the curare had blade spoilers, and the flap/speed brake was upgraded to a coupled "snap-flap".

Can't say I've flown a plane with it.

actually i meant a Cosmos.

http://www.trentonrcflyers.com/patte...0Ranc68RCU.jpg

I haven't seen any other classic that had this early Hanno flap/spoiler combo. As Rendegade points out, by the time Hanno switched to the Magic from the Curare, the configuration had changed. Matt, used separate flap/spoliers on his Arrow as we know.

David, I don't think any of the Japanese designs used this. The Cosmos in the picture simply has separated ailerons and flaps - similar to scale models. This was probably done to keep the ailerons out of the prop wash while keeping the flaps to what was considered needed.

David.

Both Super Sicroly and Curare use the combined flap/spoiler, both MAN and RCM&E plans illustrate the concept. I fly both models, Hanno says there was no trim change when actuating the flaps, both of mine go nose up, controlled by simply closing the throttle a bit more. Landings without are quick, landing with allows you to drag the model in pretty slowly so if it's windy you don't ned them, if it's a bit calm it certainly helps. I haven't used them in flight (spins) as I can't think that fast (which switch was it?) but they work really nicely in the circuit. Construction is balsa and ply, no cf or glass needed as they aren't very big, and there is little aerodynamic load on them. Standard JR 517 servo is more than enough power to get them down, even at full speed, but watch the nose-up trim!
Evan, WB #12.

Evan, 

Thanks, that's exactly the kind of info I was looking for.  How do they compare to a flap equipped plane?  I'm hoping a bit better (quicker) slowing with a bit less ballooning.  Do you still benefit from some increased lift like with flaps alone, or does the spoiler portion negate that?  I don't have the old plans to look at.  How does the spoiler portion chord compare with the actual flap chord in terms of width?  The nose up trim change surprises me a bit, as I would have expected to still see some nose down as with flaps alone.  The minimal servo requirement doesn't surprise me as I would think the spoiler portion would act something like a balancer for the flap, not to mention the rather short length of the assembly.

Thanks, 
Bob 

Funnily enough, all my flap equipped models (low wing) go nose up with flap application, different from my (limited) full size experience. I have heard of this anomaly before, possibly due to the much more rearward balances we use, compared to full size. As for the 'less ballooning' you are looking for, with the nose up trim, if the airspeed is even a bit high, the model will climb. If you leave it alone it will slow and simply fly at the new attitude, and depending on throttle setting (speed) will continue to climb, or descend depending on the initial condition. This assumes no elevator/trim input. You could mix a little elevator trim with flap operation to assist if you like, I don't as it is usefull to simply control height with throttle and leave the model to fly at the speed set by neutral trim, they do fly pretty slowly with flap down and one does not want to provoke anything nasty close to the ground... Note, you do not get 'increased lift' with any wing augmentation device, you just change the speed or attitude you get the lift. As for the spoiler/flap relationship, the Sicroly has 25% spoiler, Curare about 20%, projecting forward of the pivot and the wing sheeting recessed to fit the spoiler to match the wing section. Hope this helps.
Evan, WB #12.

We seem to have had mixed experiences.  I've only put flaps on about 3 models, and the 2 I strongly remember were a Telemaster and a CG Super Chipmunk.  The Tele was fairly neutral until the flaps were fully deployed, and then exhibited a bit of nose down.  The SC exhibited a strong nose down trim change.  I almost exclusively used these at idle power, and am not certain what they would have done with more power applied.  The SC was trimmed towards the forward range on the CG, and I suppose that may explain the difference.

I can see how this would be the case with a nose up trim change.  I probably wasn't very clear about what I meant by ballooning.  Basically, I was referring to the perceived ground effect bubble and some model's reluctance to land with flaps deployed (until the speed starts getting so slow that some really annoying things start to become significant considerations).

Agreed.  I just used "increased lift" as a convention, as most folks I talk to use that term when a model is able to continue flying at either a higher alpha or slower speed than otherwise able to unaugmented. 

Bob

OK, then. Both my models, once speed stabilised, can be landed as usual, although now little throttle movement is needed to affect height change on approach. No percieved 'ballooning/ground effect' has been detected, and I fly these when other models can't (ie windy!). Both need a determined 'round out' just before the mains touch, and you can keep the nosewheel off the ground for quite a bit of the roll out. It almost feels that the model is slightly more 'stable' flaps down than up, on approach anyway. 'Go-arounds' are really simple, more power and the nose up pitch means the model simply climbs away of its own accord, and you just do another circuit. You should see the judges eyes when you roll up with either to a pattern comp, you don't see 'wheels up' much these days, and when they see wheels and flaps down in the circuit, 10 points, easy!
Evan.

I had a couple of MK Arrows with flap /spoilers. they had slots in the wings under the spoilers. Can't remember whether I added them or they were on the plans. Worrked great however. I scratched a couple of Dirty Birdy's with them too. Worked great there too. I remember having a very short field and they made landing these speed demons easy.

Do you  mean a recessed area in the dorsal aspect of the wing in front of the flap, or are you talking about a slot for a ladder-style spoiler?  I'd like to see a pic in any case if you have one handy.

The easiest way to explain them is to picture just laying a flat sheet on top of the flap which extended forward of the hinge line about 1 inch as I recall. This was relieved into the wing to make it flush. When the flap went down, the part forward of the hinge line raised up. Under this part I made a vent as large and smooth as possible so air could flow down thru it into the lower face of the flap. I don't think flow was very good but they sure slowed the plane down and kept it from floating. As I recall I had to use some throttle and a warbird style glide slope on landing instead of just coasting in. I did try various lengths of spoiler but anything over about an inch did not improve it.

One good example was an event as a club contest called loop and land. At the go signal you had to run out about 10 feet, start the plane, take off, do 1 loop, and land and stay on a short runway. If you had flaps and retracts as I did, you had to cycle them while flying. The record was about 30 seconds. I practiced on a parking lot for weeks trying to beat this. On the day of the contest I let it all hang out and got the gear back down inches from the runway...29 sec. Without the spoiler/ flap it was not possible with a pattern plane of the day.

I don't know why these were not very popular other than it was a lot of work to add them and keep the weight down. I guess I was not much of a pattern flyer then or now.

Maybe these will help.

Not quite but they probably served the same function and probably could be deployed independently.

haha I finally remembered where these flap/spoilers came from. Try model airplane news plans for a twin pattern .40 by Dick Sarpolous called the Big Apple. His earlier similar twin was the Magnum 80. I built a number of these twins and still have plans for both of them somewhere. Great fliers. 2 of mine had K&B 6.5 pylon motors with 60 carbs and perry pumps and tuned pipes retracts. Very fast. The last one had K&B 7.5 ducted fan motors. It was just unreal with a load of nitro.....when I could get both motors running together.

bentwings,

When I read your story I see in mind this picture, is that correct?
I think for this flap the (over)centered position of the servo is important so the flap is closed but there is no "torque" on the servo.

Cees

That's it exactly. cool. I'm sure there is a force balancing factor here too. Even a big top of the line servo back them was maybe 45 oz. I don't think these flap/spoilers took much force to move as I used to play with them in the air at full speed even on the twins. They were really necessary as the plane is very clean doesn't slow down very fast. Just make sure the spoiler part is well attached. If it ever came loose while landing......well just hope somebody got a good video. haha I had to edit this after I looked at the drawing again. The spoiler air actually goes in front of the interior trailing edge because of construction of the wing. The idea is correct however.

The Big Apple is my favorite twin. It's very easy to build and with todays carbon fiber you could add a little and run .60's on it. Not very expensive to build either. It's great flyer. Very fast and stable. I had many flights with one motor out and never had a problem. The hardest part of running the 7.5 fan motors was setting them rich enough on the ground so they wouldn't go too lean in the air when they came up on the pipes yet they had to have enough power to get off the ground. They had a lot of rpm available and they would really unload in the air. It was usually a pair of plugs a flight and the props were pretty close to the ground so even the slightest bump and it would be a pair of props too. I often just chopped the throttle just before touch down. I was a lot younger then and heavily involved with pro drag racing so it wasn't unusual to toss a lot of parts away. Money didn't mean much back then. A buck for a plug and another for a prop. Big deal. I often would buy 30 plugs and 30 props at a time. The LHS would usually give me a deal. We would pour more nitro on the ground in a weekend than I used in a month with the model airplanes. A single loaded racecar piston cost more than a 7.5. We could burn all 8 several times on a heavy weekend so toasting a 7.5 wasn't a big deal. It was more like how soon could I get new ones. We were definitely not very "green" back then......more like pitch black head to foot, the only thing green around us was money. It was really something to be young and get paid a lot for having fun running all over the country with a big hot rod. Today, I sure wish I would have packed away some of the loot. haha There will never be times like that again so it's a good memory.

After I get moved I'm going to dig out the plans for the Big Apple and look into building a pair. Definitely will have 60's maybe even 90's. I'd even consider electric if the weight could be kept down. You could clean up the nacelles even more. It would have to be capable of at least 120 mph however. Probably paint it like a warbird since that's what I do now. Have to have flap/spoilers, retracts, improved landing gear, gear doors, maybe a speed brake like an F-9-F or F-18. Modern warbirds always have lots of laundry" hanging out while landing.

Sorry for the long wind. Guess you can tell I like these twins.

I appreciate the replies.  The pics of the Big Apple's flap/spoiler combination is what I had in mind, although I didn't realize that the wing was slotted to redirect airflow from the spoiler.  That is the direction I am planning on going, since I plan on using the torque tubes for the flaps.  I'm uncertain if I will slot the wing, or just hope that the spill and induced drag from the spoiler will be adequate for effect without the wing slots.  I would assume that you would want to build a sealed chamber in the wing if you were using the slots.  Slots and a chamber go a little beyond what I was planning on for a KISS build on the US.

Bob

Bob,

It is whatever you want, and I think a flap without a slot will do.
I did make a picture of the way you can make it easy when you want a slot, and maybe this is also the way the drawing of the Big Apple does show us.
Make the TE spar of the wing (near the TE of the flap) of light balsa but massive, you can cut out the slot later if you want.(See the blue part of the picture.)
You do not have to make the slot over the whole flap LE, see the picture. I show one section of the flap, there are 4 I see, one small three normal.
With the torque link you still can make an overcentered position of the linking to keep the flap closed without any torque on the servo axle.
I think lowest position of the torquelink and hinge in the TE of the wing is the best, to keep the distance between TE wing and LE flap, bottomside, as small as possible in closed position.
Just to make my story complete.

Success Cees

That's nice Tarus. I think today I'd go with the slots (sealed internally) as I originally did. Then as test I'd cover the slots top and bottom with tape and try it. You would have a positive answer. I like that. I don't don't like second guessing. I like the self locking feature too.

Did I miss something in terms of a mechanical self-locking feature, or do the exposed slots on the wing bottom draw a vacuum that helps keep the spoiler closed (via the occluded upper wing slots) along with the airflow over the larger flap surface helping hold the smaller spoiler closed?  Lack of a positive lock and the possibility of the spoiler edge catching airflow and trying to fight the servo was one concern I have.  I can see how the spoilers pictured on the Curare would self-close, but I'm asking about the combined unit as seen on the Big Apple.

TIA

Bob

I was refering to the way Tarus shows the servo linkage.

Bob, you write

Did I miss something in terms of a mechanical self-locking feature

I think the over pressure on bottom of the wing and sucking pressure on top will give you no trouble in normal flight position, so probably that will be a natural self locking feature I think.
It seems to be a little bit undefined because you still can have some leak from “over” to “under” pressure.

But.

First; you want a certain closed position and the adjustment of that is possible with an (over)centered position of the linkage of the flaps to the servo’s. See the picture 1.
In closed position the leverage on the servo is zero and the adjustment not critical. You even can pré-adjust some force to keep the flap closed and reduce the leak with soft sealing.

Second I think this kind of linkage give a more linear effect of the brakes to dosing. I compare these kind of flaps with the characteristic of butterfly valves, so very effective/sensitive in nearly “closed” position, especially with the slots, but nearly not in more “open” position. The linkage gives a sort of "exponential"

Last and for me most important point (double security!).

Whenever your plane turns over in inverted position and for example makes an inverted loop, nearly any green force (see picture2) that did want to close the flap becomes a red force trying to open one of them, that’s the moment Murphy probably will catch you by opening one of them a little and in an inverted dive maybe more. Will the yaw be the same as an engine quit? I do not know but like to play the safe game.
Even with a servo failure in closed position the result can be the flap will not open by the aerodynamic forces, for that a little (2 degrees) over centered position will be better than centered!

Cees