Greetings:

I just received the latest copy of Model Airplane News (yes, I've been flying R/C airplanes about a decade longer than I've been flying real ones--I actually started my writing career in R/C magazines), and saw that two companies are marketing models of Patty's 2001 Extra (and if you look closely at the pictures, one even has a blond in the cockpit).

Anyway, this got me thinking about a question I've had for a long time. In R/C, the aerobatic folks really do some mind-bending things with these models. They've become very inventive with manipulating traditional control surface movements to increase maneuverability. For example, to increase pitch performance, they mix in some down aileron with up elevator movement to increase pitch performance (for tighten loops, etc.).

My question is does any full scale aerobatics aircraft have these kinds of abilities. I would think that with traditional cable or rod linkages it'd be difficult if not impossible to do things like that, but then again, I've learned that I should never underestimate the inventiveness of determined people.

The other issue I can think of is with tighter loops, etc., it would increase the G load on a real pilot (not an issue with models), and you guys are on the edge already, so such changes may not be desirable anyway. But to recall some of my research about air combat over the years, isn't it true that humans can take higher G's for short periods of time? I believe I've also read that the effects of G on humans are cumulative, so that just adds to the complexity of it all. Interesting stuff.

Thanks for any insights!

Ben

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• RE: R/C control surfaces vs. the real thing,DHamblin, 12:21z, 05-15-02
  • RE: R/C control surfaces vs. the re...,Ben Chiu, 19:57z, 05-15-02
• RE: R/C control surfaces vs. the real t...,AlanParkinson, 00:07z, 05-17-02
  • RE: R/C control surfaces vs. the real t...,DHamblin, 13:39z, 05-17-02
  • RE: R/C control surfaces vs. the re...,Ben Chiu, 18:06z, 05-17-02
    • RE: R/C control surfaces vs. the re...,AlanParkinson, 01:00z, 05-18-02
      • Fly by wire stability and control,Ben Chiu, 05:53z, 05-19-02
• RE: R/C control surfaces vs. the real thing,ChipB727, 23:33z, 05-19-02
  • RE: R/C control surfaces vs. the real thing,DHamblin, 15:18z, 05-20-02
    • RE: R/C control surfaces vs. the real thing,ChipB727, 16:40z, 05-20-02
      • RE: R/C control surfaces vs. the real thing,p51mstg, 16:23z, 12-13-02
        • RE: R/C control surfaces vs. the real thing,DHamblin, 19:30z, 12-13-02
          • RE: R/C control surfaces vs. the real thing,djpacro, 23:34z, 12-13-02
            • RE: R/C control surfaces vs. the re...,Ben_Chiu, 19:12z, 12-14-02
        • RE: R/C control surfaces vs. the re...,Ben_Chiu, 23:30z, 12-13-02
          • RE: R/C control surfaces vs. the re...,DHamblin, 14:04z, 12-14-02
            • RE: R/C control surfaces vs. the re...,Ben_Chiu, 19:12z, 12-14-02
              • RE: R/C control surfaces vs. the re...,DHamblin, 19:38z, 12-14-02
                • RE: R/C control surfaces vs. the re...,TorqueRoller, 01:24z, 12-15-02
                  • RE: R/C control surfaces vs. the re...,DHamblin, 19:46z, 12-15-02
                  • RE: R/C control surfaces vs. the re...,Ben_Chiu, 02:38z, 12-16-02

Dave Hamblin
(formerly DaveH on old site!)

Some of the wilder RC planes have more control throw than typical full scale (yes, I also fly RC and full scale) plus the very high power to weight ratio allows some very interesting results. They also have a more aft CG than you would likely find in a full scale plane, though I know some top end pilots have a more rearward CG than the certified planes do (This puts them in the Experimental category ).

Wayne Handleys Turbo Raven was the closest I saw to this type of ability. I haven't seen the turbo Sukhoi yet, but it too may be in that category.

Greetings Dave:

> Some of the wilder RC planes have more control throw than typical full
> scale (yes, I also fly RC and full scale) plus the very high power to
> weight ratio allows some very interesting results.

Ah, yes, I forgot about that. The hovering airplanes with their noses pointed straight up is wild. (Very scary too!) I have an Hirobo Shuttle, so I'm used to R/C helo's at close quarters, but the hovering airplanes scare me.

> Wayne Handleys Turbo Raven was the closest I saw to this type of
> ability. I haven't seen the turbo Sukhoi yet, but it too may be in that
> category.

Thanks for the info. I'll do a search for them and see what I can find out.

Ben

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Hi Ben,

I've a vague feeling that the Alpha aerobatic plane built as a research project by the Cranfield College of Aeronautics here in the UK may have had that sort of cross-coupled controls. That was presumably entirely mechanical, but their crowning glory was the electronic system installed in a BAe Hawk fighter, which enables the aircraft to accurately simulate any aircraft from a small and lively jet fighter, to an Airbus or 747. Stick forces, stability, and even aircraft weight and response rates can all be dialed in at will.

Alan

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Dave Hamblin
(formerly DaveH on old site!)

Thats does bring up another possibility RC models have that the current full scale aerobats don't, the ability with the current high-end computer radios to couple controls to each other (flaps to elevators, rudder to aileron, elevator to ailerons etc) plus the ability to control the servos response to the stick (linear, expotential etc) does allow the model to be able to do things the full scale ones currently cannot.

Greetings Alan:

> I've a vague feeling that the Alpha aerobatic plane built as a research
> project by the Cranfield College of Aeronautics here in the UK may have
> had that sort of cross-coupled controls.

I've done a search on this and can't find anything about it on the net. Will keep looking tho.

> That was presumably entirely
> mechanical, but their crowning glory was the electronic system installed
> in a BAe Hawk fighter, which enables the aircraft to accurately simulate
> any aircraft from a small and lively jet fighter, to an Airbus or 747.

Gee, a fighter that flies like a 747... now I'm no fighter pilot, but I'm thinking that would be a bad thing.

> Stick forces, stability, and even aircraft weight and response rates can
> all be dialed in at will.

Very interesting, a real aircraft simulator!

Ben

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Hi Ben,

> I've done a search on this and can't find anything about it on the net.

My memory is more than a bit vague on this, and I can't find the info I had recently. I had the name wrong, its the A1:
http://www.eureka.findlay.co.uk/archive_features/Arch_Automotive/plane/plane.htm

> Gee, a fighter that flies like a 747... now I'm no fighter pilot, but
> I'm thinking that would be a bad thing.

Well, that all depends on "Why".

It's not to make a fighter fly like a 747 in combat, but to have a single aircraft which can be used to train test-pilots to handle anything an aircraft manufacturer might throw at them.

You want a Concorde today, sir? Sure, it takes off and lands at that very characteristic nose high attitude, at the correct speed of 180 (or whatever the figure is) , accelerates at the right rate, ... Likewise for almost every aircraft whose flight envelope is contained within that of the basic Hawk's characteristics.

> Very interesting, a real aircraft simulator!

Puts a new slant on "as real as it gets"

http://www.cranfieldaerospace.com/applications/hawk.htm

Alan

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Greetings Alan:

Thanks for the links. Very, very interesting stuff. Now if they can make a fighter "feel" like a 172, I might be your man!

Ben

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I knew some day this question would pop up. I often pondered the same issue. At one time I was researching ways to decreasing stall speed by drooping the ailerons making a flapperon set-up with a screw-drive trim actuator. It would help with landing speeds making it a little easier to squeak one on. But I could never get the nerve up to try it on an acro plane. To be quite honest I thought people would think I was crazy. But who knows! As Dave says that's what experimental category is for. Not really sure how the spades would react to this. I have drooped and raised the trailing edges to help with pitch reducing the amount of trim tab needed for level cruise flight. Anyhow Great Topic let's get some ideas brewing. I'm gonna start digging for those drawings.
Blue Skies,
Chip Bonner

Dave Hamblin
(formerly DaveH on old site!)

On the RC side, the hi end radios have either 2 or in some cases three control rate switches. Set on hi rate, you can have 45-50 degrees or more travel which allows some great 3D maneuvers. How ever, its way too reactive for normal flight or landings. Thats where the multiple rates come in. Switch to a lower rate for normal flight and landings, hi rate for the wild stuff.

Another option is expotential (hope I spelled that right) where you tailor the controls reaction to stick movement. This is what I use mostly. The control reacts slower to the initial movement (allowing normal control) but will progressively move further to the stick movement so you can have a lot of throw for aerobatics.

I would think a full scale would also need some type of rate control so it wouldn't be a heart stopper to take off and land (or do a cross country).

Chip, what are the throws on say an Extra 300 on the elevator and ailerons??

The 300 Aileron travels are @ +/- 35 degrees. The Elevator is @ +/- 28 Degrees. in full acro dress. We have explored in the neighborhood of 40 degrees. The limiting factor is the spade arm/plate wanting to touch the bottom of the wing. The feel depends on the speed naturally. But i have heard of 400 degrees a sec @ 200 kts is possible in a 300S. When I say full acro dress I mean all gap's sealed, P-strips in place for better centering, everything hitting the red lines, etc..... My Flapperon idea would only allow @ 10 degrees of trailing edge down travel due to the travel limits for full deflection maneuvering.

Dave, what kind of r/c radio has that kind of capability? I'm still a beginner in the r/c world - I need to put both horizontal and vertical stabilizers back on my LT40 after an engine failure on my last flight of the year this fall... NGAA (Not Good At All). Something I try to avoid in my C182....

Did we decide that "normal" control throws for r/c planes range somewhere in the 45-50 degree area and for a "full-sized" version are in the 35 degree area?

Also, I'd suspect that the size of control surfaces is different, even for scale models. Can anyone shed some light on this?

I realize I've been out of "the loop" for a looooong time - lots of changes to AerobaticSource.com, and it will take me a while to get "up to speed"......

I use a JR 8103 computer radio. It allows me to program control throws (its best to get it close mechanically), mix channels (aileron to rudder, elevator, flaps etc), dual rates (hi/lo), and expotential. Expotential is cool because you program how the surface reacys to the stick movement. It also hold 8 models in memory. Once trimme din, you can store the trim positions and then set the trim controls to neutral (for each model).

For example, on my 1/4 "Patty" Extra, I have a lot of throw in rudder, elevator, and ailerons. With linear reaction, the plane would be very touchy and sensitive (ie: hard to fly). With expotential I can have small movements of the surfaces with "normal" movements of the stick, and it moves more as I go to the limits. Its hard to explain but around neutral the surfaces don't move much as the stick does, but as you move the stick farther the expotential ends up that at full stick movement you have total travel.

Makes tumbles and the like easy, while making the plane easier to control while just flying.

I must also mention that you don't necessarily just want to put in all the travel you can in an RC plane. The size of the surfaces, CG location etc enter in. Go to far too quick and you may have a model that is difficult (or impossible) to control.

I generally start with the manufacturers recommendations and experiment from there. On high rates, my RC Extra has a lot more throw than recommended (with lots of expotential), but I have a low rate setting with less throw and expotential for landings.

Dave Hamblin
(formerly DaveH on old site!)

The Australian Airtourer aerobatic/trainer from the '60's had interconnected flaps/ailerons. Travel was limited so no advantage over a normal control system.

A KZ-8 modified by Wagner back in the 60's had interconnection between the elevator and flap. He went on to develop the Acrostar which also connected the ailerons to the flaps and elevator. Apparently it worked well. Eric Muller flew it in the 70's and early 80's.

Gordon Price's Ultimate 10-100 had flap/elevator interconnection as did at least one modified Yak 55.

The Cranfield aeroplane had, when first built, a conventional control system (still has as far as I know).

I've always pushed aileron travel as far as I could, as mentioned by some-one else there's usually a geometry limitation before the aerodynamics gives up.

Regards,
Dave Pilkington

Greetings Dave:

> A KZ-8 modified by Wagner back in the 60's had interconnection between
> the elevator and flap. He went on to develop the Acrostar which also
> connected the ailerons to the flaps and elevator. Apparently it worked
> well. Eric Muller flew it in the 70's and early 80's.

Very interesting. Any idea why he stopped flying it?

> Gordon Price's Ultimate 10-100 had flap/elevator interconnection as did
> at least one modified Yak 55.

I wonder if the net gain was negligible in comparison to the added weight/complexity. It'd be interesting to know what happened.

> The Cranfield aeroplane had, when first built, a conventional control
> system (still has as far as I know).
>
> I've always pushed aileron travel as far as I could, as mentioned by
> some-one else there's usually a geometry limitation before the
> aerodynamics gives up.

Thanks for the information, Dave!

Ben

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Greetings Bob:

> Did we decide that "normal" control throws for r/c planes range
> somewhere in the 45-50 degree area and for a "full-sized" version are in
> the 35 degree area?
>
> Also, I'd suspect that the size of control surfaces is different, even
> for scale models. Can anyone shed some light on this?

Aerodynamic "scale effect" (at least for cars, I suspect it's the same for model aircraft) generally produces results that are lower than their full size counterparts (air molecules remain the same size although the surface areas are smaller) under the same conditions. In addition, most RC aircraft are way overpowered, and built lighter (lighter wing loadings) than compared to their full size versions, so it kind of throws everything out of kilter.

In the end, regarding control throws, there's a minimum (the minimum to produce enough control to fly safely), and there's a maximum (where the control surfaces bind, the servo limit, or the control surface produces undesired effects). Where you set them in between these two extremes becomes a matter of personal preference on how far you want to move the sticks to get the desired performance. Although I don't fly scale much any more, I like to set my aircraft to be very twitchy so I don't have to move my thumbs very much to fly (getting lazy in my old age I guess <g>), but it also affords me greater performance if I need/want it without flipping switches on my radio.

To contrast this, most beginners would be better served by using shorter throws in an effort to reduce sensitivity and over-controlling tendencies, PIO's (Pilot Induced Oscillations.), etc..

As Dave mentioned, the best place to start is with the manufacturer's recommendations and make adjustments up and down from there.

HTH.

Ben

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If you have money to burn, you could add either a gyro system to your plane on one or more axis (which damps any uncommanded motion, but won't fly the plane for you), or add one of the new auto-pilots that would recover the plane to level flight.

Lots of ways to spend money!

Take it a step at a time. I once had to watch my new Skybolt RC bipe spin into the trees on its first flight because I had a too far aft CG, spun real good; just wouldn't stop!

Dave Hamblin
(formerly DaveH on old site!)

Greetings Dave:

> If you have money to burn, you could add either a gyro system to your
> plane on one or more axis (which damps any uncommanded motion, but won't
> fly the plane for you), or add one of the new auto-pilots that would
> recover the plane to level flight.

I have a R/C heli and while I would probably never attempt to fly it without a gyro, I would think that for a new fixed wing pilot, one might be better off with a more stable aircraft (trainer) than developing bad habits by using a gyro from the start. I suppose if one always flew with a gyro afterwards, it might not be such a bad thing, but I think you might become dependant on an R/C pro to test fly your airplanes for you for first flights (they all need adjustments--more so with a gyro installed).

I've never tried one of the autopilots, but I think one of those, newbie or not, may save you a lot of money in the long run.

> Lots of ways to spend money!

Yep! The funny thing is R/C can cost as much as flying the real things!

> Take it a step at a time. I once had to watch my new Skybolt RC bipe
> spin into the trees on its first flight because I had a too far aft CG,
> spun real good; just wouldn't stop!

But it must have been a real exciting few minutes!
I've seen my share of re-kitting airplanes too. I don't know many hobbies that can produce that kind of adrenaline rush without putting your life on the line.

Happy Holidays!

Ben

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At one club I belonged to, one of the competitors for the RC Tournoment of Champions (TOC) was practiceing there with a 44% scale Ultimate bipe with a 4 cylinder engine. This ting was way too cool. Cost was supposedly over $10,000.

After a couple practice flights, while finishing up his third, he did a knife edge down the runway, after rolling wings level he began (compared to earlier ones) an easy pull up when the left lower wing departed, soon followed by the upper. The plane spun in on the end of the field quite spectacularly. When he flew, we all stopped so he had the field to himself. After the thud, it was dead silence for a few seconds when my youngest son said somewhat loudly "Daddy, he crashed!" I said "hush son, I think he's about to cry anyway..."

I've never used a gyron on a plane, but I think on the rudder it might help some people with tail draggers; I've been told they keep them fairly straight on takeoff/landing roll.

Now if the weather will give me a break so I can get up in the C150.....

Dave Hamblin
(formerly DaveH on old site!)

With bigger control surfaces and more throw you can do more wild manuevers for both fullscale and R/c. Take a look at kirby chambliss's flight http://www.chamblissaerobatics.com/media/kirby2.wmv and you can see that bigger control surfaces deffinatly help with flying and Jurgis Kairys flying the sukhoi 31 http://www55.tok2.com/home/oh1ninja/motegi2k2/27_YURGIS_05_inverted_cobra.mpg Also r/c airplanes do things that seem to defy the limits. But the cost alot as Dave mentioned.. i recently just purchesed a 40% Edge 540 for $6,000. There is a picture of me hovering my plane. I dont use gyro's mainly because you really dont need them, and also its cheating for flying.

Plus I am not aware of any insurance for RC planes, so if you put it in you eat the cost.

At least we have insurance on the C150

Dave Hamblin
(formerly DaveH on old site!)

Greetings Torque:

> With bigger control surfaces and more throw you can do more wild
> manuevers for both fullscale and R/c. Take a look at kirby chambliss's
> flight http://www.chamblissaerobatics.com/media/kirby2.wmv and you can
> see that bigger control surfaces deffinatly help with flying and Jurgis
> Kairys flying the sukhoi 31

OMG!! I've never seen anything like that before (at least non-RC). That's absolutely fantastic!

> Also r/c airplanes do things that seem to defy the limits. But the cost
> alot as Dave mentioned.. i recently just purchesed a 40% Edge 540 for
> $6,000. There is a picture of me hovering my plane. I dont use gyro's
> mainly because you really dont need them, and also its cheating for
> flying.

Great looking airplane and fabulous shot. Thanks!

Ben

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