CAN ANYONE SETTLE THE CASE OF LH AND RH TURNING PROPS ON A TWIN FOR ME?

Hi Dan
If you turn the prop to the top, it should turn away from the fuselage to start and run. That is easer for me to keep straight than left motor should turn right hand. Hope this makes sense.

Dan, what is the question?

On full-scale, props rotate in opposite directions to counteract P-factor and torque yaw.

- George

GEORGE
IS IT NECESSARY TO HAVE COUNTERROTATING PROPS FOR TWIN ENGINE RC PLANES?
I HAVE HEARD BOTH SIDES AND A TRYING TO GET INFO
BEST
DAN

Dan I have a twin with counter rotating props and a twin with regular motor. The only difference is on take off you don't have that tork pull and in a big loop it is easer to keep the wing level with counter rotating motors.
A tail dragger twin would be happer with counter rotating motors. But either way it is not that big of a deal. If I was going to build a big Misquetio over 100 WS I would try to go with Counter rotating motors. The bigger prop the more tork.

RICH
WHAT'S A LOOP????????
I'M JUST HAVING A HARD TIME GOING STRAIGHT
THANKS
FOR YOUR INPUT
LOOKING FOR A ROYAL P-38
TRADE
BEST

Necessary, absolutely not. My TF DC-3 had two wankels, both turning in conventional direction with no issues. Also, I have seen Ziroli (1/8 scale) DC-3's and one 13' w/s B-17 (four engines) with props going in same direction.

Having said that, in larger birds with larger, higher torque gas engines, counter-rotating props would make it easier on the rudder during taking off or acceleration/climb.

You may also hear about the OEI (one engine inoperative) advantage of engine torque counteracting asymmetric thrust if you have props turning inward (opposite of what Rich describes above). For example, if right engine quits, and left engine is turning inward (conventional rotation), this left engine's torque produces left yaw (as with all normal single engine models) that counteracts the right yaw developed by the engine thrust being on the left side of the plane.

Again, when you use the word necessary, I have to say it's not based on experience.

- George

OK
NOW I HAVE A COUNTER ROTATING CONVERSION KIT COMING IN FOR ONE OF MY UPCOMING PROJECTS
IF I HAVE A 2 CYCLE WHY IS THAT NECESARRY?I MEAN A 2 CYCLE WILL TURN IN EITHER DIRECTION (AS WE ALL KNOW)
WHAT AM I MISSING?
ARE THER THREE BLADED COUNTER ROTATING GRAUPNER PROPS AVAILABLE

Dan:
One man got it right.

My number two twin will take off and fly with only the left engine running. I have not managed a take-off with the right only. This airplane has both engines with conventional rotation.

Number three twin, with counter rotating engines, can be flown with either engine running.

I also prefer three bladed props. Left hand (Pusher) three blade props are extremely rare on the ground, so far I've found none suitable for my planes.

Counter props on your twin,
. With one dead the air's not so thin.

Bill.

PS: Being specific, the right engine, as viewed from the pilot's seat, is the one that has to turn "Backwards." wr

THIS IS GETTING VERY INTERESTING SO NOW LET ME LOOK AT THE MOUNTAIN FROM THE OTHER SIDE
SAY I HAVE A FORD TRIMOTOR CENTER ENGINE 90 WING ENGINES FREE WHEELING WITH 6 PITCH
THE SIMPLICITY OF A SINGLE AND THE AUTOROTATION OF SLOW AND SHORT LANDINGS?
THIS WAS TOLD TO ME AND IT MAKES SENSE
ANY TAKERS ON THIS SITUATION?

Dan:

Ford, Fokker, Junkers, Ansaldo-Balila, whatever, it doesn't matter.

One running engine in the center with dumies outboard, you have, and are flying, a single engined plane, with all the advantages and disadvantages that pertain. And it would fly better if you left the props off the dummies - less drag.

One engine and two dummies?
. Should be buried with the mummies.

Bill.

Dan:
I'll jump in here. William Robinson is exactly right Look at the diameter of an auto-gyro. It's effectively the wing of the aircraft. It produces lift with the drag being used to effectively turn it. If you have all three props on the same axis, the powered prop in the center will produce thrust while the outer free rotating props will only produce drag. Effectively they will act as brakes. There is no auto-gyroscopic effect.

John

BILL AND JOHN
MY TERMINOLOGY WAS WRONG..WHAT I MEANT WAS THE CONCEPT WILL GIVE YOU A SLOW APPROACH AIRCRAFT MUCH LIKE SPEED BRAKES
NOT AUTOGYROATION
IF YOU WANT A SLOW PLANE AND LIKE TO FLOAT WITH ALL THE ADVANTAGES OF FLAPS AND OR SPEED BRAKES WOULD SEEM THIS WOULD BE THE TICKET
RIGHT?

Dan:

Nope. It's not the ticket.

Low wing loading is the ticket, if you want a floater. And there is no other ticket, except a true autogyro or helicopter. Low wing loading is a lot easier.

Eight feet in the air, you balloon;
. "Too soon!" the instructor yells, "Too soon!"

Bill.

Adding drag and slowing the aircraft does not make the aircraft handle well at slow speeds. Flaps, for instance, have the side-effect of added drag, but it's real purpose is to change wing chord to give better lift coefficient (i.e., lower stall speed). Free spinning props only give you drag, nothing for better lift.

- George

WELL BACK TO THE DRAWING BOARD
THANKS GUYS
WHAT AWORLD OF KNOWLEDGE IN THIS FORUM

one thing to remember is that elevator controls speed trotle controls altitude.if you want to slow down add up elevtortill almost at full stall and land that wayalot different than flying it onto the runway.

ALMOST FULL STALL........THAT'S THE SECRET

Dan, is your CAP LOCK stuck?

THAT'S THE ONLY WAY I CAN MAKE THIS WORK

ACTUALLY THIS DRIVES MY WIFE CRAZY SO I DO IT ALL THE TIME

I am trying to change the rotation of a 25 cc converted

weedeater engine. engine rotates counter-clockwise,

we are trying to make it rotate clockwise.

please advise.


Mike

Mike:

If it's a rotary valve, pretty much forget it. If it's a reed valve, or a "Three port" (piston controlled intake) it's simple. You don't have to do anything with them. The mechanical parts don't care which way they turn. Only problem is ignition timing. And that's not hard.

If you plan to use the flywheel magneto, check the coil position relative to TDC and the magnets, cut a new keyway in the flywheel to offset the magnets an equal amount on the opposite side of the coil at TDC. You're finished.

The exception here is the "Fuji ATM." For that to work you have to turn the magneto core around also - it uses the air gap on the core extension to get its "Automatic" timing advance. But this is only with the Fuji engines.

If using an electronic ignition system do the same flywheel trick with the pickup on the crankshaft.

Some of the spring starters can be reversed also, making the cconversion look like a "Factory" job.

Counter-rotating engines are the top.
. But where do you find a backwards prop?

Bill.

PS: If your engine has a rotary valve, some are easy, some are a pain. Come back with particulars, or any questions. wr

Backwards props an easy ringer
call your pals at factory Zinger

Flying2Bill:

That rhyme is strong, fellow.
. You're the new Longfellow!

Bill.

PS: Are you planning to update Hiawatha? Haw!