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Sky9pilot
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Re: First catajet build
Reply #8 - Jan 3rd, 2017 at 4:20pm
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I've had pretty good success with the Japanese Ohka and the Lockheed F-94C Starfire.  I have some posted on HPA here will need to post them on S&T also: Click Here

There are several others as well in that category.
Tom
  

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Charac-52
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Re: First catajet build
Reply #7 - Jan 3rd, 2017 at 2:18pm
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You are so right Tom, when I got home I cleared the work bench for the next build, not sure what it will be yet.
Steve
  
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Sky9pilot
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Re: First catajet build
Reply #6 - Jan 3rd, 2017 at 11:17am
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Looks like you are making great progress.  Sounds like a good start on the flights.  Be careful CLG's are highly addictive! You'll find yourself constantly thinking of the next CLG and when you go flying you'll totally be wrapped up in the CLG's!
Tom
  

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: First catajet build
Reply #5 - Jan 3rd, 2017 at 8:12am
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Managed to get the Scorpion in the air today and the results were encouraging. Weather overcast with a light breeze and intermittent gusts, in other words not ideal.
Best results when launching into wind at an angle of approx. 30 degrees and a half pull on the cat. at the top of the climb she would level out and make a wide left turn.
If the launch angle was to steep and/or to much pull on the cat. she would stall and spiral onto the groumd.
Best flight time was 8.69 seconds with a second best time of 8.29 seconds, average times about 4-6 seconds.
On her last flight she hit the park railings and snapped off the port side stabiliser.
  
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Charac-52
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Re: First catajet build
Reply #4 - Jan 2nd, 2017 at 8:07am
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The pods do look warped on the photo but I did take care to align them to the fuselage, however, because this is my first attempt at a catajet I have decided to remove them, it will be one less factor if the plane proves difficult to trim (if it flys at all)
With any luck I should get it in the air tomorrow.
  
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staubkorb
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Re: First catajet build
Reply #3 - Jan 2nd, 2017 at 4:34am
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Check out my reply (click HERE).

From the photo of the finished model, it appears like the pods might be warped (could be lens distortion).  Those things work like huge forward rudders.
  

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Sky9pilot
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Re: First catajet build
Reply #2 - Jan 1st, 2017 at 6:52pm
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Nice job on your first try.  Refine your CG with glide trials when you can before catapult launch.  In trimming you might want to use Gurney flaps (usually short strips of 1/32"sq or 1/16" sq) placed at the trailing edge of your stab or ailerons for trimming.  These can be added to or trimmed shorter for less/more effect.  Some fellas will warp the stab to achieve this but I found that the Gurney flap works easier and doesn't change with flights. 
(Gurney flaps comes from Dan Gurney's NASCAR design on the top of his race cars to help recover when his car was bumped or lost traction and spun out.  A flap on the top of the car would pop up as the air raced backwards over the top of the car!!)  JFYI
Tom
  

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Charac-52
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Re: First catajet build
Reply #1 - Jan 1st, 2017 at 8:09am
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Some detailing added.
  
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Charac-52
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First catajet build
Jan 1st, 2017 at 4:55am
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Here is my first build, a Northrop F-89 Scorpion, wing span is 8 inches with an overall length of 8 1/2 inches.
Weight is 10.1 grams and requires 1.7 grams on the nose to attain balance 1/3rd back from the leading edge.
I have made some attempt at sanding an aerofoil section.
The plan called for a laminated fus. but 1/8th balsa was all I had hence the ugly looking launch peg.
I'm sure I have made mistakes with this build but I wanted to get something in the air and learn from that.
  
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