supafly

My Feedback: (4)

Are there any constant speed props available for RC aircraft? Any with feathering capability? I've kicked the idea around of building a scale twin, but id like prop and mixture controls just like the real thing...

Flying freak

Would be extremly expensive and would have to basicly be a heli head typa set up, remeber that the more you put in these big projects the more that can fail,

Steven

Flying freak

also if youd want the airspeed to be a constant and the pitch change automaticly youd need some sorte of peto tube setup maybe running to a turbine ecu to be able to contorle the pitch?

Scar

My Feedback: (3)

Check out the electric forums. There is a variable pitch prop available for electrics that includes pitch reversal - they can hover nose-down. Not designed for fuel engines.

Mixture control linkages were supplied by Du-Bro and Sullivan at one time, but as I recall they dropped them due to no demand.

Regarding scale twins, I question whether additional complexity is what you really want. Seems like everyone else wants the twin engine operation simplified, not made more complex. Thus there are a couple of twin engine monitoring systems available. If your system requires an adjustment, you won't know until you hear it a couple seconds later at the pilot station. By then, it's a little late to react.

Good luck,
Dave Olson

supafly

My Feedback: (4)

It's actually the prop that is a constant speed, not the airspeed... The full scale props use a governor and oil pressure to adjust the pitch and maintain the rpm....

JohnBuckner

My Feedback: (1)

There are some varible (manually controllable) props used in electrics but no Constant Speed props as such and typically used on full scale aircraft. That would require engine govenors to alter pitch as loads increase or decrease on the propellor such as climb and descent. Actually if it was avaliable it would buy you nothing with our aircraft never in extended climbs or descents.

Mixture control actually is avaliable on just a few engines such as my rear exhaust Rossi used in a vintage type pattern plane. Agine this is almost perfectly useless with the minor exceptions of certain type venues such as above or a situation I have run into in my XC flights in the past and that is the enrichment of the mixture due to changing elevation along the route of 3000 feet and of course that is predicated by the route choice.

If you want to do a multi, great it is educational, a challange and fun. But first make sure you are proficient in single engine airplanes first and your first twin should not be a scale type but something more appropriate of which there are more choice out there now than ever or kit bash a simple twin which is my favored suggestion to folks who want to get into multi's.

The addition of both the above features to a scale multi is virtually useless in most cases and actually could be detrimental due to the overfocusing on such things when there are more important considerations.

John

supafly

My Feedback: (4)

I am more than proficient in single engine aircraft (as far as RC goes) and even had a twinstar a few years ago. I fly full size multi's and am used to the procedures associated with flying them... I'm just looking for something that is more challenging and complex than just retractable gear and flaps... I guess the mixture control would be pretty much useless because the pressure change associated with climbing from the surface to maybe a max of 500ft AGL is minimal... (merely 0.5in/hg)

JohnBuckner

My Feedback: (1)

Not only is a controllable mixture totally useless it also will cause engine stoppages whill trying to screw around in flight. No sir better to go to the trouble of learning proper multi engine tuning methods before you takeoff in every case.

Any kind of controllable and or feathering prop is not only useless in our applications but also will cause a crash most likely if you try feathering in flight upon an engine loss while you are screwing around with it. All for virtually no benefit. the majority of our multis will maintain flight on one engine if and this is a big if the proper procedures are used.

I have taught litterly hundreds of full scale add on's and a somewhat lesser number of RC multi flyer to maintain control and flight on one, not just shut the other engine off and land and as you well know timely and proper imputs must be made but don,t think for a minute that you full scale training will help when the time comes to do something in a few seconds. The problem is in full scale its easy, yaw direction is obvious and the time honored 'Dead Foot - Dead Engine' is just not going to work for you.

Another point full scalers get tied up with it is counter rotating (inward counter rotating, not outward counter rotating like the P-38) It does buy you a slightly lower VMC with the critical Left out as you were taught in ground school but the differance is not hugh and very few modern engines are conviently converted to run CR. This in itself causes folks to get hung up on some old engine that did conviently allow this but also for other reasons are not really engines I would care to use in twin.


John

supafly

My Feedback: (4)

I know that a constant speed and/or featherable prop would serve no real practical benefit, neither does any other scale add-on (scale rivets, rigging wires, struts etc.). The point of scale flying is to make it look real and simulate real operations with the aircraft... I once came in behind a twin that declared an emergency and had a feathered prop. Aside from how serious the situation was, I couldn't help but be amazed at seeing the aircraft land with one prop completely stopped.

JohnBuckner

My Feedback: (1)

Left propellor removed:

http://video.google.com/videoplay?do...06427302&hl=en

TFF

I believe that turbo prop model engine has a constant speed prop but I think it sells for $10 grand. I think you would need a geared engine so you can have some prop efficiency because a prop tuning 10000 rpm would be hard to control accurately, and the governor would be pretty big to work so there would be a lot of weight. The prop would be pretty hefty too, to be strong enough not to destruct. There has been controlled props in pattern but they were never strong to be safe, but today you could mimic it with the heli throttle collective mix in your radio. Back in the 80's the Russian control line scale team had home made featherable props; dont know how they worked.

GRANT ED

You could adapt a heli head as a constant speed prop and use an electronic governor in place of a mechanical one. This would be very difficult as you would need to custom make many bits. If you want something a bit more complex then how about a 4 engined B-17 [8D]

Flypaper 2

Built one for a Quadra 50 quite a few yrs ago. Worked fine on the test bench but never got around to trying it in a plane. Still out in the garage on the engine somewhere.