36" Long Fin Alignment Task...

[Johnnie]

I am two for two on getting excellent feedback for this project, so now I am going 3-for-3:

I have a set of 1/4" plywood fins (strakes), 36" long, that I need to mount to a 5.5" airframe. They need to be mounted directly in-line with the booster fins, and run true the full length.

There is very little warpage in the strake, but there is enough so that I will have to 'babysit' the epoxy ensuring the strakes remain true, aligned and without warp.

Now in most builds, I would mount these fins using 5-minute epoxy, but because of the length of the mounting surface area (36") I feel I would run out time before I could get everything in line set for cure.

1st pic is of the typical warpage I have to deal with...

2nd pic show the strake as mounted rear...

pic is a front shot...

I would sure love to have some tips and tricks for this challenge...

Thank you,

Johnnie

View attachment SA_TRF 31.JPG

View attachment SA_TRF 32.JPG

View attachment SA_TRF 33.JPG

 

[kandsrockets]

Use a piece of alum. angle iron 48" long. Clamp it to the rear fin and then put your forward fin against the angle iron and clamp.

 

[Johnnie]

Use a piece of alum. angle iron 48" long. Clamp it to the rear fin and then put your forward fin against the angle iron and clamp.

Great idea Scott. I have a .75" X 36" piece of angle that I have used to mark fins for many years, That I believe might just work. I will hit Lowes today and see if they might have a longer piece (48"), with longers legs, say 1" to 2" legs.

Johnnie

 

[tater1337]

another trick

shave a 2x4 down to half* the thickness of your tube, lay your fins on it and hold the fins down with weights, then lay your tube next to it and glue one side. estes did this with one of their kits, had a fin with a root edge the whole length of the rocket.

*actually half the thickness of your tube, then shave off half the thickness of your fin

 

[Johnnie]

Thanks for the tip Tater1337, it seems I remember gluing my fins on to my SR71 BlackBird a few years back using similar, and obviously scaled down, method.

As it has turned out, I purchsed a 48" long X 1" wide piece of Angle, 1/16" thick for $4.88 @ Rocket (Home) Depot, and it has worked out just great. It has taken the better part of 8-hours to get three of the 36" stakes mounted, and this evening I will mount the last one, and the 4 smaller 12" tips. I am hoping to have a nice semi-dry fit pic posted at the rockets original thread later this evening.

Johnnie

 

[talkin Monkey]

Johnie,

Hope this helps. Kinda like krcontruction but with screws instead clamps.Pic may be too big to upload here. If it fails send me a PM with your e-mail and try it that way.

Scott

EDIT: I don't know where this picture went. But it didn't kick it back as too big. ??? Area 51 time.