Im setting up an original Kwik Fli from the 60's and need to know what throws to use on ailerons and elevator. Thanks




Scott R

Scott, thats really nice!!! I emailed jeff as I pm you no reference to control throws. Jeff said he would get back to me on it. will post as soon as I get them. I'm sure somebody here can help you out. Pete

Very sharp looking Scott!!! I happen to have a copy of the MAN construction article and guess what, there's no mention of control throws in the article. Go figure.

FB

That is one very attractive model. Congratulations! <G>


Ed Cregger

Thanks everybody!! Maiden flight today with sucess, Very fast and tons of power with the GMS 61. Pretty good adrenaline rush too!! Some small issues: It felt like I had two much control throws and CG to far foward but not sure, just got get those dialed in and I think im there. Any help would be great. Thanks, Scott R

Congrats on the maiden! Glad that it went well! What a great way to end the year!

FB

Scott congrats on the first flight, I looked @ the Plans and the CG shows 4-1/16 in. from the leading edge of the wing. it does not show a foward or aft. limit also show the wing with 1/16 in. positive incident. I still have not heard from jeff on the control throws. hope this helps.

happy new year!, Pete

Just finished striping and lettering, really dressed it up!!

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A somewhat forward CG with lots of control throw was the style way back when. We used to max out the controls and run the balance point back far enough to just snap roll and spin. As the years progressed, the balance point moved rearward and the control throws were reduced somewhat.

In those times, we did not fly with the balance point so far rearward. Why? Because you never knew exactly where your servos were going to find neutral. The forward balance point desensitized the model to minor errors around neutral.


Ed Cregger


Corrected spelling

Ed, thanks for this valuable background information. It's as interesting for me as several others before. Somewhat reliving my youth when I couldn't afford it, I built the Kwik-Fli in a simulator. There I can duplicate your statements and also the usual setup values given on plans.

Scott, you have a very nice model, with the original paint scheme even enhanced. Considering the nose landing gear and the canopy, it must be a Graupner version so it should be at least early 70s.

As to the control throws: There are recommendations for the ailerons. The RC MODELER article says: Total aileron deflection is only about 5/8". The German plan version says about 16 mm, what's just the same and converts to about 11 degrees. I'd recommend to set 11 degrees up and 10% differential.

Rudder deflection is limited to 30 degrees by the elevator cutout, and I'd set both rudder and elevator to 30 degrees. You'll need all rudder effect you can get (after all the Mark III had that bigger rudder), and 30 degrees elevator won't cause a stall inadvertently, but you'd even need it for spinning and snapping.

Of course a more back c/g helps also. The plans show it exactly 4" behind the leading edge, what gives a rather big 13.5% static margin (proving Ed's remark). By the way, that matches the decent decalage recommended in the plan. RCM says wing leading edge 3/32" higher than trailing edge, the German plan says 1.5 to 2 mm. That converts to 0.3 to 0.4 or even 0.5 degrees incidence/decalage.

Under today's circumstances (see Ed's remark), I'd set the c/g to even 5 1/8" (well, carefully in steps) giving a more pleasant 3.5% static margin. The model will barely stand on it's main wheels (what was recommended in this forum for other pattern models). Incidence/decalage should be reduced to 0.1 to 0.2 degrees to make the model pretty neutrally stable both upright and inverted. With the stock trim it's stable only upright and needs substantial elevator inverted.

Maybe you'd have to somewhat close the throttle of your powerful engine to notice that.

I have it balanced at 2-5/8" from L. E. with batt and receiver as far back as I can get without adding weight.

Scott R.

You may want to move the battery further back so you can get the CG to at least 30%. I hate having the battery behind the radio gear for obvious reasons but it looks like your only solution. That GMS engine must be darn heavy.

GMS 61 is 26oz with Muffler

My O.S. 60F-SR from the 1970s weighs only 20.8 oz with muffler, that would be more adequate. Your engine's muffler looks rather big, maybe it is the heavy thing and could be replaced.