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Scale RCM 1/3 Scale Champ Build

TonyHallo

TonyHallo

150cc
Made new engine standoffs from 5/8" steel round bar, each one is 2 ounces heavier than the aluminum version. Added 12 ounces of shot to the cowl and made two 8 ounce pucks from epoxy and shot formed in a 4 ounce applesauce container. I save the containers as my grandsons eat the applesauce, think I got 6 on Friday. They are really handy and the epoxy pops out after it cures..
I went back and checked the CG calculator. I had assumed a standard stabilizer efficiency originally, when I put in low efficiency the margin drops to 2%. This is what the calculator states "Choose Low Stabilizer Efficiency if the stab is close to the wing's wake
or behind a fat fuselage in disturbed flow"
Tomorrow I'll check the CG again.
IMG_1480.JPG
 
Snoopy1

Snoopy1

640cc Uber Pimp
Tony do me a favour. I know there are complicated methods of calculating CG which includes the fuselage and stabilizer . There are several different approaches and some that just do not work. Can you just do a standard 25% Mack of the wing and measure to The CG that you have calculated and tell me the difference. Just interested to see the outcome.
Or even the difference between the CG percentage that you used and the calculate that same percentage for the wing and see what the difference is.
 
TonyHallo

TonyHallo

150cc
The cord is 20" so 25% is 5". With the added weight the cg is 5 3/4" or 28.7%. I've flown tail heavy planes where when rolled inverted the plane climbed at a 45 degree angle and pushing down elevator to land, still had control. Of course this was an aerobatic plane with airfoil stabilizer. This was something different, I had no control laterally but didn't notice any lack of pitch control, very odd.
 
M

MarkY

Guest
Tony, just a few suggestions. Have seen you fly and chances are you have already done my suggestions, but here they are anyway;-) I have a few hours in a full scale Champ. It is a "Rudder" airplane. Adverse yaw can be quite active. Have you set up differential aileron travel? Also lead your rolls with some rudder. Making a turn with a high angle of attack will exacerbate the adverse yaw. Notice at 45 seconds on the video. Adverse yaw will make you feel as though the ailerons are backwards. Your take off and landing were GREAT.

The landing gear looks like it works as well as the full scale. Nice and smooth. The most enjoyable (To me) aspects of the Champ is the smooth landing gear and being able to see over the cowl while taxiing negating the need to S turn.

Beautiful plane.

Mark

[QUOTE="TonyHallo, This was something different, I had no control laterally but didn't notice any lack of pitch control, very odd.[/QUOTE]
 
Last edited:
M

MarkY

Guest
Here is a short video of the Champ I learned to fly with. No, I had nothing to do with flying on skis as I was out of the club for several years before this was filmed. It is still flying and is parked at Mt. Pleasant/Scottdale (International) Airport.


You may notice in a couple of scene the pilot needed to put in a little more rudder after initiating a turn. Love the sound of the mighty 65HP Continental. I believe that it now has an 85HP Continental with a starter.

Mark
 
Snoopy1

Snoopy1

640cc Uber Pimp
TonyHallo said:
The cord is 20" so 25% is 5". With the added weight the cg is 5 3/4" or 28.7%. I've flown tail heavy planes where when rolled inverted the plane climbed at a 45 degree angle and pushing down elevator to land, still had control. Of course this was an aerobatic plane with airfoil stabilizer. This was something different, I had no control laterally but didn't notice any lack of pitch control, very odd.
Click to expand...
That is strange looking at the video does not represent the CG numbers. Something else is going on and I have no suggestions.
 
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