- Joined
- Jan 27, 2009
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I had done a 2.6" version of the BSG Viper that flew quite well by using an oversized wing painted black to hide all but the scale viper wing outline. I had thought of doing an upscale but was not convinced that I could get it to come out at a reasonable weight. However, working on my X-15 full fuse using BT-101 I played around with openrocket looking at masses and locations/length and figured if I used a MDRM 4" nose cone I could probably get something around 27 ounces less motor that would work with just minor nose weight, something around 1 ounce only. With the longer nose cone profile I trimmed the body tube back to keep the overall length the same proportion as my smaller version.
I worked up the dimensions using 1.54 scale factor for the tube diameter ratio and it came out to be. 43" length, 4" diameter, 37.75" wingspan, 31.8 ounces ready to fly with F-25/26 29mm motors to around 450', or with 1/2 ounce added nose weight I could fly on G-38 or G-40 motors at 33.2 oz rtf to 600' or so. I did spend a lot of time belt sanding down and then smoothing the nose cone becuase the outer diameter was too large at the rear with the thinner bt-101 tube. Then I had to cut the top and cut a foam filler plate for the front.
For the wings/tail I used 9mm depron for stiffness with a small spar in the vertical stab and two 1/8" spars in the wing. I'll work my way up with the motors to make sure I'm not pushing the speed too fast to cause flutter. I normally try to keep my boost speeds below 120fps but these are simulating at 150, 170 and 200fps. The span of the wing is well supported and pretty stiff.
I did insert some stiffener foam vertical plates in each bottom half of the side boosters to help on landing to support them.
Here she is balanced and ready to go, just waiting on motors and the decals from stickershock.
I worked up the dimensions using 1.54 scale factor for the tube diameter ratio and it came out to be. 43" length, 4" diameter, 37.75" wingspan, 31.8 ounces ready to fly with F-25/26 29mm motors to around 450', or with 1/2 ounce added nose weight I could fly on G-38 or G-40 motors at 33.2 oz rtf to 600' or so. I did spend a lot of time belt sanding down and then smoothing the nose cone becuase the outer diameter was too large at the rear with the thinner bt-101 tube. Then I had to cut the top and cut a foam filler plate for the front.
For the wings/tail I used 9mm depron for stiffness with a small spar in the vertical stab and two 1/8" spars in the wing. I'll work my way up with the motors to make sure I'm not pushing the speed too fast to cause flutter. I normally try to keep my boost speeds below 120fps but these are simulating at 150, 170 and 200fps. The span of the wing is well supported and pretty stiff.
I did insert some stiffener foam vertical plates in each bottom half of the side boosters to help on landing to support them.
Here she is balanced and ready to go, just waiting on motors and the decals from stickershock.
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