Loc Onyx a good candidate for TTW fins?

[CQBArms]

Anyone build it with TTW? Any fin modifications needed?

 

[RevKeith]

I built mine with TTW fins. Traced original fins on 1/8 inch ply and added the tabs that go through the body tube. All that's left is to cut the slots in the body tube. Make sure you check the CG/CP with the added weight to the rear of the rocket.

 

[bsexton]

Didn't really see much need for the recommended motors.

 

[RandyM]

I wish I had with mine. Came down in a parking lot on the first flight and broke off a fin. It was easily repaired, but TTW would have held up better.

 

[Stymye]

I think It's a good candidate, I built mine that way but flying on a sod field It probably didn't need it.

 

[Fore Check]

I don't think it needs it if you use the proper amounts of the proper adhesive (HINT HINT HINT: Ditch that smelly epoxy and use wood glue where it should be used.)

The design of the rocket (amount of available space in the body tube compartment) does not lend itself to using much more than a 29/180 casing, and the reloads for it won't push an Onyx past mach (so no worries on the up part)

Further, if built correctly with good fillets, a rocket of this weight should be able to come in without a parachute attached and survive unless it lands on a parking lot or road or rock. Normal landing field, I'd expect survival. Again, this is because of the strengths of the building materials and if they are attached with the PROPER adhesive.

 

[astrowolf67]

I've reuilt my Onyx three times now. On the last rebuild, I cut new fins with ttw tabs. Since I couldn't get inside to do internal fillets, I drilled holes and poured in some foam. The last time I flew it, a high speed deployment caused the body and nose to slam together pretty hard. The nose hit right at a fin body joint, and the fin held up great. I can't say the same for the body though.

I'd recommend ttw on the Onyx. I took care with mine, making sure all the glassine was removed from the joint area, used the epoxy rivet method, and even a bit larger chute. All it took, was one good solid landing on a fin to rip one off.

 

[Art Upton]

The Old Time 80s method was to drill holes into the body tube along the fin glue joint mark.

Sand off all the glassine on the joints, then use yellow wood glue and glue the fins on the root. The glue will form rivits into the tube.

Then use good fin to body fillets with the yellow glue.

On kraft tube to wood, yellow glue works better then expoxy.

 

[2muchstuff]

Originally posted by Fore Check
Further, if built correctly with good fillets, a rocket of this weight should be able to come in without a parachute attached and survive unless it lands on a parking lot or road or rock. Normal landing field, I'd expect survival. Again, this is because of the strengths of the building materials and if they are attached with the PROPER adhesive.

Fore Check - have you flown an Onyx? If so, how did you build it?

I quit flying my Onyx. I know how to build kits, use wood glue, and make a mean fillet. But on nearly every single flight, I suffered *de-lamination* of the paper tube. The fins stayed on the the tube just fine, but the tube itself de-laminated. There's no easy way to fix that - I can't just glue the fin back on because it never broke off. The surface mount fins and fillet are still intact and stuck to the surface layers of the paper. (I did lightly sand the surface of the tube to rough it up a bit.)

I've never tried the idea of 'glue rivets' - drilling through the body tube before gluing the fins on. That might help. But the real answer is TTW fins. There's no reason not to use them - other than the added weight of the fin tab.

I even tried using an oversized chute, but the wind speed was just enough that the sideways motion of the rocket when it hit the ground was enough to damage it.

The Onyx has taught me to never build a rocket like that again without TTW. I'm not sure what the breakpoint is between surface mount and TTW, but for me, the Onyx is on the other side of that point.

As always, your mileage may vary.


tms.

 

[Fore Check]

Originally posted by 2muchstuff
Fore Check - have you flown an Onyx? If so, how did you build it?

Sorry fory your luck with your Onyx.

My Onyx has 3 flights on it: a G33-7J, an F52-8T, and a G79W-10.

All three flights have been picture perfect (well, the delay on the G79W flight seemed a little long, but no damage or zippers.)

I used a lime-green 24" ripstop chute from Thrustline Aerospace on all 3 flights.


I can still beat the fins on a table like I was using the rocket as a hammer or mallet and have no loosening, no delamination, nothing. Solid, solid rocket.


I built it as per the instructions, simply using wood glue for the fin attachment. I did not drill any rivets or anything spectacular. I just sanded the glassine off of the body tube at the fin root and fillet area using 80 grit sandpaper. For the fillets, I poured in the yellow glue and let it dry. Took nearly 2 days for them to cure because I laid it in so thick. They're not the prettiest fillets (aesthetically) but they sure do work. But I don't mind, you can't tell in this launch pic on that G33-7J.

 

[Art Upton]

Originally posted by 2muchstuff
.......
I quit flying my Onyx. I know how to build kits, use wood glue, and make a mean fillet. But on nearly every single flight, I suffered *de-lamination* of the paper tube. ..

Hi 2much,

My onyx floated away in the 90s with probably less then 5 flights on it.

BUT I have an NCR big brute I built with the drill tube rivits method in '88. This is the old one with surface mount fins, ACE nose cone etc.

It has about 30 flights on it, and was the rocket I flew for my Tripoli confirmation in '89 with an H motor.

I have had one fin come off on that rocket due to an issue on landing in a parking lot, and it glued right back on like a jig saw puzzel, torn parts to torn parts. Even the paint went back in place with no repainting nessary.

I last flew it this year at Michigan International Speedway on a F26FJ and a G79W.

But I will add, TTW is a better construction method.

I like it best however when I can get the tabs to the motor mount between the centering rings,

Like on the Weasel

 

[Stymye]

Originally posted by bsexton
Didn't really see much need for the recommended motors.

Bsexton,
Sweet job on that !.. I really like the decals too, are they Vinyl or waterslide mabey?

Here's mine that I built to demo Roadrunner motors with.
It has yet to take to the sky but I built it TTW for longevity as a motor demo rocket.(the RR G80 packs quite a punch!)

 

[Rocketmaniac]

My Onyx "CK" was built stock as far as the fins were concerned. It has about 6 or 7 flights on it with no problems. I've been flying it on G77R-Ms lately. No signs yet that the stock fins will be a problem. (and normally I over build rockets and make them too heavy)

 

[bsexton]

Originally posted by stymye
Bsexton,
Sweet job on that !.. I really like the decals too, are they Vinyl or waterslide mabey?

Thanks - the decals are vinyl and were made by Dave Rose from Graphix & Stuff.