I failed.....fin alignment suggestions welcome / Thank you! # 2190.....old guy

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grady678

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My pathetic attempt at building a Leviathan for my 4 yr. old daughter turned into a knee jerk corkscrew flight on a G40. Nonetheless, launched vertical in 15mph winds/ landed safely with surprisingly no damage. Flight was far worse than I'm describing....just don't want to go into embarrassing details.

Any suggestions for 'a quick and easy' (98percent or better) 90 degree fin alignment? Yes, pre slotted airframe.

Yep, gotta earn that L2 status back. THANKS!!!!





Richard

#2190 TRA (L2.....Circa 2000)
 
Lets see em. There could be other factors that caused your bad flight,for example a wimpy launch pad. DAMHIK
 
Your alignment on the roots might be fine, but many of us had issues with warped fins out of the package. A warped fin will act like a wing, and start the rocket spinning at a pretty fair rate of RPM.
 
One fin is warped but knew this ahead of time. Main concern is getting each fin perpendicular to tube.....not one fin lined up properly. My old rockets were 7' to 18' and fins were 12" to 20"s so alignment was quite easy on a floor template. The smaller stuff has me stumped. How are you guys aligning your fins 90 degrees to airframe........assuming the fin is 100% axis aligned.

Heavy duty launch pad (handles about 25 pound rockets) with no rod whip. I cannot believe what people charge for what they call Gun Turret pads.....are you kidding. Built mine for $8 and I might even post photos if anyone is interested.

Big Blue Launch 2.jpg
 
grady678 said:
One fin is warped but knew this ahead of time. Main concern is getting each fin perpendicular to tube.....not one fin lined up properly. My old rockets were 7' to 18' and fins were 12" to 20"s so alignment was quite easy on a floor template. The smaller stuff has me stumped. How are you guys aligning your fins 90 degrees to airframe........assuming the fin is 100% axis aligned.

Heavy duty launch pad (handles about 25 pound rockets) with no rod whip. I cannot believe what people charge for what they call Gun Turret pads.....are you kidding. Built mine for $8 and I might even post photos if anyone is interested.
Click to expand...

I wanted to get this kit, but if it has issues with warped fins why bother? I heard people who built the Mega Der Red Max and had similar issues with the fins not aligning or warping.
 
make sure that you de-select the print option of "to fit" or "scale to" and select "actual size" - that might be it but neat site, thanks
 
1) Try stepping down a notch to reduce propellant weight-this could be a Cp/CG problem (coning)
2) Check to see if the airfoil on each fin is symmetric. I'm surprised at how many folk don't even break the edge.
3) Be sure your red cap came off holding the ignitor in-this may have caused thrust vectoring off axis. Examine the nozzle to see if there was even ablation in the throat.
 
Thanks for all replies.......kind of thought people were using jigs but might try the quick and easy cardboard template first. I'll throw up a thread tomorrow or weekend to show how anyone can build an $8 to $10 launch pad/rod/platform to handle 30 pound rockets...... for RODs only .....not RAIL option. 15 minute build time. Nothing new.....just backyard engineering.

TRA 2190
Richard
 
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