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-   -   Engine Thrust Angles (https://www.rcuniverse.com/forum/aerodynamics-76/68019-engine-thrust-angles.html)

budcop 03-04-2002 12:19 AM

Engine Thrust Angles
I am completing a Waco cabin type bi plane, before I mount the new G-62 I wanted to check and see if I need to put right thrust and or down thrust in the mounting, the plans reflect no angles , down or right, Is it possible that the engine should be set zero / zero? .......Bud

GSNut 03-25-2002 02:59 PM

Engine Thrust Angles
IMHO...2deg. right and 2deg down never hurt any bipe! Of course the entire aircraft is dependent on degrees of this or that. Upper wing is 0 degrees and the lower wing is 1+, or is it the other way around. Is the stab along for the ride at 0 degrees or is it set to 1+ ?

Also check to make sure that you have a couple of degrees toe-in on your wheels along with the right and down thrust. With all this you should end up with a great handling Biplane.

It all depends on what the designer had in mind when it came to stability and ground handling.

Best of Luck with the New Bird!

budcop 03-28-2002 09:27 PM

Thanks for the info, the incidence listed on the plans is 0 top, 0 bottom, and +1 on the h-stab, also shows no right thrust or down thrust on the plans!!!!Bud..

GSNut 03-29-2002 02:31 PM

Engine Thrust Angles
Understanding forces that influence flight of your aircraft is really not witchcraft.

Consider it as leverage as in:

Your C/G as the pivot point and your horzontal stabs +1 degree multiplied by the tail moment as a lever. The varible is the speed of the air moving over the h. stab. causing....slight changes in the attatude of the entire (pitch angle) aircraft.

As your aircraft speed increases the positive force on the stab will lift the tail and roll your 0 degree set wings to actually go to a negitive figure and dampen some of the lift generated by the high lift airfoil of the wings on this aircraft. As can be expected the reverse is also true when your airspeed drops so does the tail. Thus causing your wings to roll into a more positive angle and create more lift. You must realize that all this is not a great amount of movement and is well dampened and almost inperceptive in actual flight.

It is a very well and popular thought out force arrangement for this type aircraft.

Possibly the G62 is a bit more engine than the designer had in mind. But, considering the reliability of the G62 and you can fly the aircraft in a most scale like manner possibly at 1/2 throttle. (Hint= I use the larger fuel tank with my G62's! I.E. 24oz or larger.)

I would seriously consider setting your engine to the 2 deg. down and 2 deg. right, this to negate the tourqe reaction on take offs. The effect of this mainly would lessen the corrective rudder needed on the takeoff roll.

I hope this helps and "The Best Of Luck" with your new bird.

Let Me Know How it Goes, as I am considering building one also. I checked one out at the local
hobby shop and was quoted a very nice price.

budcop 03-29-2002 09:56 PM

Engine Thrust Angles
Hi GSN, this is a strange aircraft, it is the Waco HKS-7, wingspan is 101" top wing and 87" on the bottom, It came from Norm Rosenstock plans through Vintage r/c, I think 1984, now that I am just about ready to test fly, I get worried about everything!, I will put a couple of washers behind the engine to give it some angled thrust before I go....thanks for the help...Bud..

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