Cast resin Nike Fins?

I searched and looked over dozens of Nike-related posts on this forum and the web but I have not found any references to anyone having made cast resin Nike Smoke fins. Specifically, I have an old, partial Centuri Nike Smoke kit I am building (1/10 scale) and would like to know if anyone has heard of any resin fins for this kit being produced?

Thanks -

Buzz "Great to be back in Texas" McDermott

I don't know if this will help at all, but just in case.

Scale Data:

https://www.rocketryforum.com/showthread.php?8174-scale-Nike-Smoke-Fin-Dimensions

3D printing:

https://www.shapeways.com/model/1315152/fin-unit-t-35-nike-smoke-for-18-mm-motors.html?materialId=62

Greg

L3Excalibur said:

I searched and looked over dozens of Nike-related posts on this forum and the web but I have not found any references to anyone having made cast resin Nike Smoke fins. Specifically, I have an old, partial Centuri Nike Smoke kit I am building (1/10 scale) and would like to know if anyone has heard of any resin fins for this kit being produced?

Thanks -

Buzz "Great to be back in Texas" McDermott

Click to expand...

Buzz:
Can't say as I have ever heard of anyone outside a kit manufacturer ever producing cast resin Nike Fins.
That said: I've been building Nike Smokes and other Nike Based Sounding rockets in a number of Scales for many years.
Ages ago I had an opportunity to closely examine several full size Nike fin units. I've been building my Nike fins more or less the same way ever since. They are either single or double tapers 1/8" bent alum skins welded to either a center Z stiffener or two stiffeners. The fin unit is then welded to a base attachment plate that bolts to the Nike Motor casing.

For many years I've produced this same fin form with Heavy card Stock, 14ply Sho-Card or 3/64" to 1/32" light plywood with excellent results. My smallest Nike Smoke is minimum diameter Micro-Maxx motor tube T2+ (.281") OD. and the largest Nike based model I've made was BT-80 (2.6") diameter.
These fabricated fins are Light weight and very strong. I've even used the same process with .020" Sanded Polycarbonate to produce Lighted fins for my (Phantom Nike-Apache) I'm sure you can do the same with very little trouble.
Below are a few photos that may help.

+1 on what Micro said...I love built-up fins for sounding rocket models. The Terrier fin shown has flown multiple times on F impulse.

here is the method I used to make my Nike Smoke fins to replace the solid balsa fins in my Centuri kit....

I want to thank you all for the great ideas. I have started on a fin set using David's paper-with-balsa core method. I am using basswood instead of balsa, though.

Buzz

+3 for the built-up method. I wanted toughness so I went with 1/64" plywood for the skins. These are 1/8 scale.

Thin ply is always my first choice for Nike-style fins. If you are careful, you can score the underside with the back of a slightly dull exacto blade and add a sharp crease. Better to score after removing material from the leading and trailing edges (to make sharp scale edges) to avoid possibly breaking at the score line during sanding/rougher handling.

rocketguy101 said:

+1 on what Micro said...I love built-up fins for sounding rocket models. The Terrier fin shown has flown multiple times on F impulse.

Click to expand...

David, have you (or Josh) got any info on the size of the bolts that were used to secure the fins to the motor? I've perused that Atlantic Research 12pg document (which also shows a rather unusual (to me) 4 or 5 bolt pattern (running longitudinally) on the double wedge design - most I've seen (or measured) were the two 3 bolt plates (on each side - aligned with the skin surfaces)). I'm aware of the 5 bolt, longitudinal pattern on the modified double wedge (Nike-Smoke) - just never seen nor encountered that on the double wedge pattern. It would appear the bolts are something like 1/2" dia (shaft, not head) - but that is just, "That looks about...." kind of analysis. I would assume that these would be an 'off-the-shelf' part. A little CAD work with the 10" length of the mounting plate looks pretty good with 1/2" bolts on 2" centers down each side of the fin (and about 3.25" from one side to the other).

Any info on these bolts??

Thanks in advance,

-- john.

I'm assuming you're talking about page 9 of the brochure PDF and the Heavy Duty Diamond Fin (screenshot below). I can't say for sure for that particular design, but I know that the five-bolt pattern of the Modified Diamond fins of the Javelin are spaced 2.88 apart across the fin, 2" longitudinally, and are 1/2-20 bolts (3/4" dia x 1/2" head), all on a 10.0 x 4.31 mounting plate. The H.D.D.Fin page shows a 4.25" wide plate, so if you used the Javelin spacing for bolts, it should be pretty close.



I'm thinking that the reason for a four instead of five-bolt pattern is due to the diamond root chord shape interfering with a five-bolt layout.

jcato said:

David, have you (or Josh) got any info on the size of the bolts that were used to secure the fins to the motor?
-- john.

Click to expand...

John I don't have that data, I went back through a long email trail with Josh discussing the Nike He has more information than I do...

rocketguy101 said:

John I don't have that data, I went back through a long email trail with Josh discussing the Nike He has more information than I do...

Click to expand...

Thanks, David.

-- john.

Meatball 1 said:

I'm assuming you're talking about page 9 of the brochure PDF and the Heavy Duty Diamond Fin (screenshot below). I can't say for sure for that particular design, but I know that the five-bolt pattern of the Modified Diamond fins of the Javelin are spaced 2.88 apart across the fin, 2" longitudinally, and are 1/2-20 bolts (3/4" dia x 1/2" head), all on a 10.0 x 4.31 mounting plate. The H.D.D.Fin page shows a 4.25" wide plate, so if you used the Javelin spacing for bolts, it should be pretty close.

Click to expand...

I may have put too much emphasis on that 'non-standard' design - as I was mainly interested in the more normal anchorages (5 bolt, 2x3 bolt (page 3)) - just trying to determine the bolt diameters - which you have provided - thanks. I went back and looked at the AR document and what I was seeing was that square mounting on the bottom of page 5 and on page 8 - but, neither actually shows any bolts (or holes), just the plate.

Meatball 1 said:

I'm thinking that the reason for a four instead of five-bolt pattern is due to the diamond root chord shape interfering with a five-bolt layout.

Click to expand...

That would be my thinking, as well.

Thanks again, Josh.

-- john.

Just to make sure people follow what we're talking about, here's the ARC Nike Fin Brochure.

The 16151 version of the Standard fin is the angled plate version (p2-5 are all related). You can see decent photos here. A quickie import/scale in TurboCAD based on the upper fin half in one of those photos gives me about 3/8" head dia. for those fin bolts (1/4" thread dia.) and a rectangular hole in the shroud about 11.0" long. So that's half the size of the Javelin bolts.

Page 5 corresponds to the angled mounting plates on page 3 (12 bolts -- possibly 1/4" nominal size per photo measurement).
Pages 10 and 11 are the 10-bolt layout of the Javelin (definitely 1/2" nominal size--actually, there's an eccentric nut for setting fin incidence in the lower right bolt position when looking at the vehicle in vertical orientation--not sure if it would be used in other fins or not).
Page 8 corresponds to the 8-bolt photo on page 9 (possibly 1/2" size like the Javelin fin bolts per mounting plate similarity).