BlackJack's 54mm LDRS project, true diamond air foiled fins. Space Cowboy!

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After cutting the G-10 to shape with a hack saw....yep a vice and hack saw, I put a couple drops of CA between the 3, glued the set all together & sanded them to exact shape to match. Good whack with a mallet to separate & was good to go.



Measured 1/2 from leading and trailing edge for the new bevel. Masked off & ready to sand on bevel. No fancy jigs, been doing it long enough I can eyeball it pretty good.

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Used a shop table belt sander to bevel fins by eye. I have also just clamped a regular belt sander upside down in a vice and done it that way too.

Blackened the leading and trailing edges so I could gauge how I was doing as I went.

The fin in the middle is what it looked like before the sanding, 2 outside ones are done. They came out as expected after taking removing the excess material.

I'll wrap a motor with wax-paper, shove it in the airframe to have something solid to mount the fins to when they get glued in the slots.

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blackjack2564 said:
Got one of the new spiral wound G-12 NC's for it too.

The new spiral Von Karmen is 2inches longer and 10ounces heavier than the molded version, but weight is not that much of an issue. It should weigh around 11lbs ready to fly.
(/QUOTE)

How kewl are the new NC's? Tell me tell
me tell me tell me!
 
How kewl are the new NC's? Tell me tell
me tell me tell me!

Here ya go first look.

Mine is the white one. Spiral wound and dyed white G-12. Why? I don't know. Probably made from the tow in the vat already dyed for something else. I've seen white,green,black & grey. [grey are the ones for the scale Amraam 3.5]

They will come in 38 54 98 and 6inch. Then eventually I think all other sizes in-between from you know who.... Wildman.
The BlackHawk 38mm kits are now shipping with black ones.

54mm version in standard raw green G-12 38mm's are all gone so no pic.
They come with matching coupler for tube size. Inside just as smooth as the out. They are spun over mandrels, then turned on a lathe grinder to tolerance. They are all a bit longer for their size. The 4in is 22in. vs 20 due to bottom 2inches are same as tube to engage the coupler. They DO fit perfectly into airframes and are just as strong as G-12 tubes!

Got me thinking, hmmm....... Yep it fit the case perfectly. hmmmmmmmm

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Back to the build [98]

Slots prepped by filing small V notches for more glue bite

Same for fins.

Then sanded with 60 floor machine paper and gouged up for T-T.

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Wax paper applied to 98mm motor case. Tucked over top edge and taped inside. No room on out or it would not fit.

Slipped in airframe so the fins have solid backing when I glue. Epoxy won't stick to the wax paper. I had to use a small section. I tried wrapping motor but it was to much and would not fit airframe .

JB Weld applied to slots, you can see where it's oozing out through the V's I filed to help lock in the fins. The slots were such a tight fit I wanted some extra bite.

By using a 500 watt work light for heat, I accelerated the cure to 2 hr. instead of the 15-20 that JB usually requires, enabling me to set all 3 in a day.

Fin set on , sanded, gouged & ready for next step: fillets

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New trick/tip I just figured out today. By coating edge of my fillet tool with magic marker, then rubbing it in the V-groove, it left the line I need to run my masking tape.

Requires several passes & re-coating the tool but more accurate than laying tool in groove & marking with pencil. Faster too!

Using the thick black Pro line high temp epoxy for fillets. They are 6% [radius] of the fin root approx. .75in [12in root] These will be foundation for the Kevlar overlay.

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Whatcha bringin to NERRF Jim?

I'm actually gonna fly something this time (electronics will be the FIRST thing I pack)
 
New trick/tip I just figured out today. By coating edge of my fillet tool with magic marker, then rubbing it in the V-groove, it left the line I need to run my masking tape.

Requires several passes & re-coating the tool but more accurate than laying tool in groove & marking with pencil. Faster too!...

Great idea!
 
After taping to the lines did the fillets with Pro-Line High Temp. Same stuff comes with Mongoose's.

These are big fillets, each took 34 grams of epoxy.


Removed tape 15min. into cure and place under heat lamp to expedite.

Did all 3 in day & sanded the shape in readiness for the T-T.

Had a CJ moment wondering about how strong they were.....so I laid the fincan on the floor and stood on it. Then being a little brave, stood right on the top fin and bounced a bit.

They are still on, passing the 205lb bounce test!

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I was going to use Kevlar for the first part of my T-T, but the stuff I had was really heavy weave, almost like burlap! After trying numerous methods to cut it, gave up and just went with 6oz.glass.

Took a break & watched Tony's [T-fish] video again, then began the task of making templates for cutting the glass & marking the fins. This took way more time than the actual glassing. If you ever decide to try this, make sure you watch Tony's video in the sticky at the top of high power. It really helped me speed up the process, thanks by the way Tony! I pretty much did it that way to the letter. No point in fooling with success.

Fit the overlays and marked for position.

Once I cut them all out and was ready, weighed out my epoxy and applied my 3 layers of T-T. Pretty much as in the video, 3 overlays 1/3 ,2/3, full. They should stay on after all this!

Don't have peel ply, but I'm pretty good at glassing, so I just brushed it on lightly, worked it in , cut the excess and stuck it under the heat for the night. 1 set down, 2 to go.

All went quickly and without a hitch, especially for my first time at one this size.

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The heat lamp I use [500 watt Halogen shop light] really gets it hot quick & speeds up the cure. I'll leave on for several hours.

Off to Bong later today for some fun launching rockets!

Hope to get my 54mm Av-bay parts back soon, so I can resume building & testing that beauty.

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Whatcha bringin to NERRF Jim?

I'm actually gonna fly something this time (electronics will be the FIRST thing I pack)

Hey Joel!

Long time no see, went to dinner with Robert and Gloria at Red Glare had a blast.

Looking forward to catching up with you at NERFF.

Hopefully I'll have at least on of these to test fly on something small by that time. Want to do a run with my new Raven before I ramp it up at LDRS. Have yet to break 20. These should do the trick!

I'll bring my good ole standby's along... the 3in chopped and dropped Wildman, BlackHawk 38 and some 4inch something.

See ya there!
 
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CJ, Nice project; looking forward to seeing it fly!

See you at the Bong tomorrow!

-Eric-
 
Well by Av-bay bulkhead were finished today. Eric made a couple of pieces of art! [The 54mm rocket]

The ejection charge holders are machined hex heads on the ends to make tightening them a breeze.

They replace the wingnuts. Just screw the holders on the tie rod ends and kill 2 birds with one stone. They hold 1.5 grams of BP.

Can't wait to give these babies a whirl.

On the 98mm making good headway. Finished the T to T and brushed on a couple coats of epoxy to even things out.

Some wet sanding with 400 and the fins and glass transitioning on the airframes are smooth as a babies butt. Halfway to NERFF and will post some more pics when I get back. Sure wish I could test fly these there.

On the 98 I only have 5 inches left after sticking the motor in the fincan [54inches long] so some creative thinking remains to get everything in.

Thinking about recessing the altimeters into the front 5in of Av-coupler and using the back 6 to hold apogee cordage.

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On the 98 I only have 5 inches left after sticking the motor in the fincan [54inches long] so some creative thinking remains to get everything in.

Thinking about recessing the altimeters into the front 5in of Av-coupler and using the back 6 to hold apogee cordage.
The N800 is 41" long, 42" including the protruding part of the closure. You have plenty of room. If you're planning on a 6GXL then it's 50" with the forward closure and it's a N1000 and another 4000 N-s :smile:
 
Yes, how and the exact process I will have to let Eric explain as he made them for me.


Any more info on the G10 machining process? From what I've found after a bit of googling is a 30K RPM spindle and polycrystalline diamond tooling. Eric? Curious minds want to know :)
 
Any more info on the G10 machining process? From what I've found after a bit of googling is a 30K RPM spindle and polycrystalline diamond tooling. Eric? Curious minds want to know :)

That's spot on for the opitimum set up. My equipment has to be more versatile than that. Much is sacrificed to get those high rpm's, the machine become a specialty type of thing. Loss of tourque at bottom end means loss of heavy cutting ability. Plus you have spindle brgs to replace every 2yrs at 30k rpm. I don't have room for that niche.

I'm running 10K with Polished carbide under an air Gun for this. It works well but you guessed it, Messy! PCD tooling is on the way, but that has more to do with tool life.;)

Hope this helps.

Eric Foster
 
I'm running 10K with Polished carbide under an air Gun for this. It works well but you guessed it, Messy! PCD tooling is on the way, but that has more to do with tool life.;)

Hope this helps.

Yes, but a few more questions. Is the air for cooling? What sort of system do you use to deal with dust? Does the carbide tooling have a coating or is it bare carbide?
 
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Last week was the first test flight. Flew on a EX I-85 longburn. 26lbs of thrust for 7.5 seconds in an Aerotech 38mm 720 case. Altitude of 4868ft.

Everything went as planned. Good stability. Weighed 5lbs on the pad.

I was able to achieve almost zero drag from my Av-bay attachment points & Recovery. Pics of that later.

As a side note my flight was approved for LDRS !
Still awaiting approval of the N-800 flight.

Off to mix the N beast tomorrow at Tom B's. I'll take some pics for the inquiring minds.


So far so good! This baby is really gonna cook. Now to decide what & how to paint or polish the exterior.

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