I am putting a MaxJet F35 together and deciding how to wire it. Since servo reversers are not in my plans I will almost certainly use 6 channels, although the reversers are potentially irrelevant.

Here is my question. Which control system is more efficient? I have also had the thought that I could flip a switch and turn the ailerons into flaps while maintaining elevon control on the tail.

This is uncharted territory for me. Any help is happily accepted.

Radio gear, 6 ch OrangeRx dsm2 rx and a DX7

Tim

I have the same plane. I have yet to close it up. I'm only using 4chs. I put my build as a blog under my hangar. I haven't worked on it in a few weeks now. I was waiting on batts. which are in. Now, I just have to solder the batt. connections and test, then close the plane, get the CG right and fly and trim. That should be by the end of Feb. since it is also now tax season.

Keep up the post, I'll be watching.

It is rarely a good idea to use ailerons as flaps (unless they are used in conjunction with separate flaps and the ailerons have less flap movement). The reason is when you happen to get near the stall and try and pick up a low wing, the aileron will stall dropping the wing further. Stalling the outer portion before the inner section of wing gives less warning of impending stall. On the other hand if you use flaps and flaperons it can work well as long as the main flaps extend further than the ailerons (creates a washout effect). Many full size aircraft have used this feature to good effect.
Cheers

Here is the link to the build thread at our Club site. http://badiusownersclub.com/forum2/i...ic=270.new#new It looks to be a solid plane so far. The instructions are less than exciting.

Tim

To keep things simple for this smaller EDF, Y the Ailerons and have the tail planes as Stabilators or Pitch only by Y off the elevator channel (one servo has to be reversed).

Tailerons: You could get a SM2 mixer or Vtail mixer ( http://www.dionysusdesign.com/produc...roducts_id/174 ) and Y off the aileron channel to the mixer and connect the Elevator channel to the other side of the mixer to drive the two tail servos as Tailerons Ptich and Roll.
With the other side of the Aileron Channel Y'd you can drive the ailerons.
If you want to get creative, Select Flapperon as wing type, which will make the aileron channel and the Flap channel to drive your Ailerons/Flapperons.
Still with the External mixer, have the elevator on one side and use on the other side... I don't remember if the DX7 allows you to slave channels from the initial setup. If it does slave the Aileron to the Gear channel. If the DX7 cant slave then just mix the Ail to the Gear channel and connect the gear channel to the other side of the mixer.
In this setup you have both Ailerons on the wings, Flapperons, can mix Elevator to flap for tighter turns, while also having the tailerons also helping with your roll rate since the tailerons are both Roll and Pitch.
When you extend the flapperons, the tailerons still have sufficient roll control.

Just make certain you setup your taileron servo linkage so that the linkage is in the inner most hole of the servo arm and on the outside or one in on the horn. This will make it much less twitchy and allow you full travel of the servo for the range required in the tailerons.

If you setup flapperons, you must have tailerons otherwise you will not have enough roll control from the flapperons alone.

Flapperons or flaps are fine and they Do Not cause a stall; the pilot does.
Flapperons have more area and create more lift and drag. In most aircraft it also adds a pitch moment that needs to be compensated by both Pitch and thrust. Because many RC jet pilots do not use a Stabilized approach that they were originally supposed to have learned (see AV Web http://www.avweb.com/news/leadingedg..._199047-1.html) turns into the bad habit of trying to glide in like they are the space shuttle. What catches them is with flapperons, the aircraft slows down very quick because they are not approaching under controlled power. Especially if you get gusty headwinds that suddenly slows the ground speed futher, but th airspeed then is increased causing the model to climb and then the gust stops. This leads to the pilot either then trying to power on or they pitch up and down to contol the altitude and it drops because of insufficient airspeed. They then declear that it was the flapperons that caused the stall. That's just pilot error.

Maxt. Thebenefits of washout are clear. Any aircraft with drooping airlerons (flaperons) will have undesirable tip stall tendencies unless the inner potion of wing maintains a higher angle of attack than the outer portion. Pilot error is common and passing blame is too but poor design will make life impossible for even the most experienced pilots.Cheers

You are mixing up you dynamics. Washout is as you describe and is used mainly to reduce high speed tip stall. As an aircraft does a hard pitch the root stalls first quickly followed by the tips. With additional wash tip stall is delayed. A flap also used with subsonic speed manoeuvers also are deployed to camber the wing and delay stall.
But washout is not applied in all cases where as flapperons often are like of the F/A-18 or F/A-18 E/F that doesn't have washout but lands with flapperons. They land on Carriers requiring a high stall tolerence as they seek the shortest landing and agressive glide slope. They can be stalled as any aircraft can be but this isn't due to the fact that they use flapperons; it because they are being stalled unknowingly or intentionally.

In fact all a flap is doing is just cambering the air foil. A camber air foil doesn't stall because its cambered.

So you are mixing two different techniques used for different purposes to exclude the other. Washout by twisting the wing on EDFs at this Reynolds is not recommended as it can induce other issues. What works better is a thicker foil at the tip to achieve a similar washout effect.

No MaxT.
Washout is not for high speed stall. It is for any stall (high or low speed). The idea is to allow the ailerons to function when the stall is impending (some of the wing stalled).

The F-18 is a perfect example of what I'm talking about. The aircraft has flaps and ailerons. Don't forget it also has a complex flight computer insuring the pilot doesn't lose control at lower speeds. The flaps extend and so do the ailerons but you will notice the ailerons have less deflection than the flaps when needed (impending stall (high or low speed).
If a wing begins to stall at the root it is much easier to recognize and correct before control is lost. Whereas if it stall first at the tip and aileron, control is lost before the early warning signs of stall occur.
Here are some photos to enjoy...
<a href="http://www.airliners.net/photo/USA-Marines/McDonnell-Douglas-F-A-18B/0779174/">http://www.airliners.net/photo/USA-M...A-18B/0779174/
</a><a href="http://www.airliners.net/photo/USA-Navy/Boeing-F-A-18F-Super/1154247/L/">http://www.airliners.net/photo/USA-N...per/1154247/L/
</a><a href="http://www.airliners.net/photo/Switzerland-Air/McDonnell-Douglas-F-A-18C/0821477/L/">http://www.airliners.net/photo/Switz...18C/0821477/L/
</a>http://www.airliners.net/photo/Switz...8a2d0eeb974b10

4strips not sure what the pics are illustrating. This is a non washed wing with flapperons deployed and what an aileron moving slightly. Watch any video approaches and you'll see the tailerons kick in most of the roll corrections as I originally pointed out.

Maybe this is where we are mixing the thinking. I'm saying flapperons do not cause a stall but I think you are trying to show concern of maintaining roll control via the ailerons discussing wash etc. Note I originally said not to reduce roll authority with flapperons unless he adds tailerons.

For the F35A like the SU-27 family, they have large flapperons where the tailerons maintain much of the attitude controls.
http://www.youtube.com/watch?v=tIXS9...embedded#at=49
I've done the same for both my Freewing and Laxiang F-35 and it flies a much more stable approach with the flapperons.

No need to pick at word since I said, "as you describe" and "mainly". An aircraft of this designed isn't flown into a controlled stall at slow speed and if they do, the controls change to ailerons becoming spoilers and the tailerons are greatly loaded. For an aircraft like the CF-415 that has flapperons, but never see great speed ranges, neither wash or tailerons are needed. But where modern fighters experience high pitching moments (look it up), is more so at velocity. Wash helps both the pitching moment and aileron control, where the later if lost is loaded to the taileron as mentioned before. Thus my mainly comment.

The OP will be fine with flapperons as many have demonstrated, as long as he maintains his roll control via the tailerons.

Actually, the Su-27 family uses full-time flaperons and tailerons.

I've got video of an Su-27 going through the pre-flight control check and you can see the ailerons and tailerons operating in concert with each other. I'll post it a little later tonight.

I set up my Su-27IB to use both and other than reducing the throws a little, the model flew the same as it does with tailerons only or with ailerons/stabilators.

Dan

Here's a link to the video I was talking about that shows the Su-27 pre-flight control check.

See: [link=http://SavageLight.com/video/Su-27Elevons.mpg]Su-27 Controls[/link]

Hi Dan. Yes they do but thats a ground check sequence. Try and find a video with the flapperons moving at all during the landing. You'll see the tailerons move much more than the flapperons do even with their one wheel rolled attitude landings. http://www.youtube.com/watch?v=ez34sKSye3Q http://www.youtube.com/watch?v=55c4o...eature=related
In flight they both move controlled by the FCS but again if you observe many of the manoeuvers, depending on the velocity the tailerons move a lot more than the ailerons do even for roll input.

I don't know if you looked at the continuation of my conversation with Kevin but re Elevators and tailerons one question I finally asked was why do stab/elevators make such poor roll surfaces on models. He pointed out the concern of that the taileron can better manage the aircrafts AoA. I'm still trying to formulate the actuals but with the Pitch surface much closer to AC and CG proportionally place between about the NP, the force requirement is reduced but the drag is less and the ability for it not to be blanked by the wing since it has a wider range out of the wings flow is additional reasons beyond sonic for using Tailerons.

When this is incorporated with the use of flaps/flapperons where more pitch and roll authority is required with less drag in a turbulate config the taileron is the easier but both can work if the aircraft is like an F-4 where it has dedicated roll devices and thus only requires pitch.

This OP is asking about the F35 which like the SU 27 Fam uses tailerons and depending on the speed and manoeuver, uses aileron roll or uses taileron roll. During the landings though, the roll again is loaded to the tailerons.

I would expect to see smaller movement of the flaperons when they are lowered for landing. My model did the same thing. It's done to reduce adverse yaw.

American Naval fighters such as the F-18 something similar. When the flaps and ailerons are lowered for landing, roll control is transferred to the tailerons.

Unlike American fighters though, the Flankers only reduce the aileron throw. If you watch the end of the video I posted, you can see that the Flanker has the flaperons drooped, and while the control throw is reduced a little, it still does mix flaperons and tailerons for roll control.

I'll take a look at my Flanker video library. I think I've seen footage that shows the flaperons and tailerons working together during high-speed airshow-type maneuvers.

Yes, I read the thread. That's just it. There is no hard and fast rule concerning roll control on the tail. It all depends on the airplane in question.

I've built and flown several different Su-27 models. Two with taileron controls (stab/elevator & stabilator), One with ailerons/stabilators that was also could be changed to fly with and flaperons/tailerons. My brother's Flanker had full-time ailerons and stabilators. They all flew the same. Roll control was effective (without excessive taileron throws) regardless of the control configuration.

My brother Daren built a small model of an Airbus Beluga and tried to use taileron control and it was completely ineffective in the roll axis.

On the Flanker family of aircraft taileron controls alone are effective because the tail span is equal to the span of the ailerons. On the Beluga, the tail area is enough to stabilize the pitch axis, but too small for the roll axis.

You can't use tailerons on the F-4 because of the extreme anhedral. When you deflect both surfaces to roll, it acts like an inverted V-tail and yaws instead. And, you have to limit the flap travel on Flankers, etc. because of the turbulence washing over the horizontal tail.

Like I said, on the Flanker family of airplanes the mixing is full-time, unlike American fighters which transfer roll control between the ailerons/flaperons and the tailerons depending on the flap position.

Here's a couple of pics I found online that show the Flanker mixing flaperon and taileron controls with both the flaps down and up.

Totally agree. I incorrectly implied that the flapperons are fixed. They are not. This is also true of the programming on a model. The flapperon when deployed will still move slightly with roll input but since they are near their max deflection, they move much less in comparison to the Tailerons. There are a few rough landings of the SU's where as it bounces on one wheel and then the other you can see the flapperons move either by the stick or FCS. Other times you can see these one wheel landings and they add a snap roll correction with the taileron moving quite a bit, but the flapperon movement is not apparant.
I took this to be and FCS setting depending on the pilots choosing. I'll ask my relatives again what the setting are.

For the F-35 its hard to tell which is favoured since there is so little clear footage. But they are using all the surfaces in many of the test rolls, air braking and landing configs. Just not sure which is the dominent but from some footage it appears to be similar little movement in the ailerons and more roll correction in the tailerons.

I've found them not to be the same for say a Cobra. I had a hard time getting a stab/elevator to cobra well. Tailerons or stabilators, there was no issue.

Those pics are the in flight config where the FCS is reading airflow and engages the LE Flaps and the flapperons to reduce the stall point but are still being used as roll along with the tailerons. Its when its on its final landing where you see a notable reduction in movement from the flapperons. So if you read back they do work together, its on final that most of this is loaded to the tailerons. I'm trying to find one of the footages that show this, where like I said you had a strong taileron movement with what appeared to be none from the flapperons. The ratio is handled by the FCS either way or at least that's what my inlaws advised.

No need to continue the search. We are in agreement here.

It's my belief that the Russian and American fighter FCS are programmed differently. Whereas the American fighters will drastically reduce or remove completely the roll control from the ailerons and transfer it to the tailerons when the flaps/ailerons are drooped, the Russians merely reduce the flaperon throw to minimize adverse yaw with the flaperons and taileron roll control operating full-time.

Americans use finesse and the Russians use brute force to accomplish the same thing.