Dave,

I think I added some tools for you to use on the discs I made for you. One of them is a program for making tube marking guides by entering the diameter of the BT and the number of fins. If you can't find it, try this link.....

http://www.42nd-dimension.com/rocketry/templates.html

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Don
NAR 53455
"Carpe Diem"

Thanks Don, but I've already tried that. I get an error that says, "Template is too large for selected paper." I even tried using legal paper, same results.

Edit: Also tried using landscape paper orientation with both letter and legal paper, same results

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Dave
Fire is the leading cause of fire.
Was once SAM#0132

Well Dave......here's how I used to do things when I didn't have a template or guide. And I didn't use geometry because I had to think too hard. Piece of string wrapped around the body tube and marked where they come together (circumference). Measured and laid out on paper. Then divide by the number of fins. This gives you a line edge for your guide plus the dimensions for your fin placement. Just need a parrallel line and right angles to complete your template. By math....C=d*pi. Again, find circumference and divide by the number of fins for placement along the circumference. For a 4" diameter BT, the circumference would be about 12.57" (that's why it wouldn't work on 8.5X11 paper). For three fins, they would be seperated by about 4.19" and four fins would be seperated by about 3.14".

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Don
NAR 53455
"Carpe Diem"

I've been working on this on and off for almost 4 years. I chickened out and surface mounted the fins versus going TTW, but t has some serious epoxy fillets..don't matter much though she'll probably never fly.

Anyway, finally painted her yesterday--now I just need some decals.

I give you the "Der Kolossal Red Max"..........

Attached Thumbnails

 

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Dave
Fire is the leading cause of fire.
Was once SAM#0132

Probably never fly... why?

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NAR # 115523
Once upon a better day... SAM #0076
My site: http://rocketry.gonnerman.org

Because he forgot the motor mount.....

Just kidding. That looks great Dave. Well worth the four years. Now just design some decals and get Gordy to make them.

I've got an 8' rail we can launch it with if you've got some rail buttons. I've got some somewhere for my plastic conversion but haven't been able to locate them yet.

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Don
NAR 53455
"Carpe Diem"

I guess I'll fly it someday, it's just condsiderably larger than what I'm used to. It weighs over 2 pounds empty.



Nah, it's got plenty of motor mounts - 3X29mm, and a launch lug, rail buttons may be a better option though.

Decals are another story, it'd take a ream of decal paper....

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Dave
Fire is the leading cause of fire.
Was once SAM#0132

Three F motors should get it going good. It wouldn't need high power, just mid power.

If you want decals for a 4" diameter rocket, vinyl is the better way to go.

http://www.stickershock23.com/Der_Red_Max.html

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SAM # 0011

The aggregate of three F's, though mid-power motors, might put it into the HPR realm. I'd have to look at Doug Sam's handy-dandy graphic to be sure though.

For AeroTech RMS, a G71R (max liftoff mass of 2135.124 grams) or a G76G (max liftoff mass of 2564.162 grams) should do the trick. It won't fly high, but should be safe AND impressive.

For AeroTech SU, a G80T would work (max liftoff mass of 1966.163 grams).

I would sim those 3 motors and see how they do.

The liftoff mass is per my calcs. YMMV.

Greg

I too was thinking about it being HPR. A full F is 80Ns. Using the nominal woosh factor for APCP (~specific impulse) of 2Ns per gram, then a full F would be 40g of propellant. So three of them is getting close to the max limit of 125g. If the motors use any of the milder compositions, then it could well be over 125g. OTOH, many F motors are well shy of the max impulse, so, even if they use one of the milder formulas, they may still be under 125g. Gotta look at the mfgr spec sheets or TMT/NAR cert docs to be sure.

What should be of greatest concern is getting three APCP motors lit at the same time. It's a whole lot harder than lighting three BP motors. My two attempts at siimultaneously lighting composite motors weren't very good. I got one of two Road Runner F's lit for an airstart with no ill effects. But the 2 of 4 G's that lit on my upscale Ranger left the rocket retired on its maiden flight

I haven't really mastered this yet, so I can't offer a lot of advice. But ignitors with bridge wires were suggested to me.

I've wondered about but haven't tried effecting the Cesaroni style ignition using an e-match to ignite a stationary BP pellet at the top of the motor. Not sure the kosherity of doing it that way

Doug

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YORF member #11