Difuminar: 9400 feet and Mach 1.6 on a CTI G150

[TRFfan]

Those are some small fins! The rocket looks good so far,
When do you plan to launch this? When you do, make sure to post some pics & some vids if you can!!
Thanks,

I plan to launch in September. The nose cone is going to be weighted with 35 grams of tungsten so it should be stable

 

[blackjack2564]

UPDATE; Recieved body tube and fins from carolina composites. I roughed up the body tube a bit to help the fins get a better grip of the surface. I still have to get the proline 4500 (its out of stock right now) and syringes. If i can get someone to redesign my fin guides i can have them tacked on to the body tube soon.

View attachment 316015

You can use JB Weld for fillets. It will be fine on this. You could have saved yourself all that money & hassle, if you got your guides from CC. I think he charges 20.00 for a set. Since he made the tube and fins....guides would be a perfect fit. [ so is his 6 -1 cone]

I would guess around 45 degrees.

The bevel is close to 10 degrees.


Good luck on your flight.

 

[TRFfan]

You can use JB Weld for fillets. It will be fine on this. You could have saved yourself all that money & hassle, if you got your guides from CC. I think he charges 20.00 for a set. Since he made the tube and fins....guides would be a perfect fit. [ so is his 6 -1 cone]









The bevel is close to 10 degrees.


Good luck on your flight.

I was thinking like this.

View attachment 316106

I didnt know he had guides.

And yeah i will try JB weld.

 

[neil_w]

Those are some small fins! The rocket looks good so far,
When do you plan to launch this? When you do, make sure to post some pics & some vids if you can!!
Thanks,

Gonna be hard to catch that on camera, seems likely to teleport outta there. Should be interesting!

 

[TRFfan]

Yeah according to OR the max acceleration is 854 m/s.

 

[TRFfan]

Ok, now that you can edit posts again, i updated the introduction.

 

[TRFfan]

Fin guide shipped. Should be here in a few weeks. In the meantime I'll try to get the JB weld and 5 minute epoxy next time im in town.

 

[boatgeek]

You've probably looked at this already, but you might get a higher altitude off of the G65 longburn motor. It's a hair more N-s and you'll lose less to drag from high speed. Of course, if you want altitude plus a couple of Machs, then the G150 makes a lot of sense.

 

[TRFfan]

You've probably looked at this already, but you might get a higher altitude off of the G65 longburn motor. It's a hair more N-s and you'll lose less to drag from high speed. Of course, if you want altitude plus a couple of Machs, then the G150 makes a lot of sense.

From the original post;

Out of the Pro24 6 grain motors the G150 was picked to be the propulsion system for this rocket. Most other motors in the Pro24 6G case offered less impulse than the G150 except for the G117 and G65. The G65 offered a longer burn time as well as more impulse but the offset core produces stability issues and weathercocking....................

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[boatgeek]

From the original post; [/RIGHT]

Derp. Reading comprehension fail. Fair point about the offset core.

 

[EeebeeE]

Out of the Pro24 6 grain motors the G150 was picked to be the propulsion system for this rocket. Most other motors in the Pro24 6G case offered less impulse than the G150 except for the G117 and G65. The G65 offered a longer burn time as well as more impulse but the offset core produces stability issues and weathercocking. The G117 has a longer burn time and just 1 less newton/sec of impulse than the G150 but the G150 has more ISP and less weight and so produces better performance.

Why not the G-65? same total NS, but a longer burn rate puts this at a higher altitude and the roughly same speed when your motor burns out.

 

[TRFfan]

https://www.rocketryforum.com/showt...-Mach-1-6-on-a-CTI-G150&p=1683711#post1683711

 

[EeebeeE]

Why not the G-65? same total NS, but a longer burn rate puts this at a higher altitude and the roughly same speed when your motor burns out.

Never mind...answered earlier. Although to prevent weather cocking you could go off a 10' rail instead of 8'.

 

[Nytrunner]

I was thinking like this.

View attachment 316106

I didnt know he had guides.

And yeah i will try JB weld.

Unless I'm missing something, That doesn't look like 45 degrees.

 

[Incongruent]

I think he meant 4.5

 

[TRFfan]

Unless I'm missing something, That doesn't look like 45 degrees.

Sorry, i didnt draw that correctly.

 

[TRFfan]

Fin guide came in today.

 

[TRFfan]

I will get some pics up later.

 

[TRFfan]

Ok, i tacked the fins on with CA but the rocket slipped from my hands and now the tip of one fin is chipped a little. What should i do?

View attachment 316700View attachment 316701View attachment 316702

 

[TRFfan]

Also planning to get this for fillets.

https://www.homedepot.com/p/J-B-Weld-Weld-8265-s/100189012

 

[dhbarr]

Sand 'em all even. If dropping from the hand chipped it, the air-at-speed or landing would have done the same.

 

[TRFfan]

So just chip all the fins?

 

[tim cubbedge]

So just chip all the fins?

Sand the other fins so they are the same as the chipped fin. You can probably clean up the chipped fin with some sand paper too.

 

[TRFfan]

Sand the other fins so they are the same as the chipped fin. You can probably clean up the chipped fin with some sand paper too.

oh ok. Ill try it tomarrow.

 

[rocketgeek101]

Ok, i tacked the fins on with CA but the rocket slipped from my hands and now the tip of one fin is chipped a little. What should i do?

View attachment 316700View attachment 316701View attachment 316702

I would just round off all the tips with some sandpaper. It's looking good!

 

[retortec]

Did you prep the fins and tube surface for your adhesive? The root of the fin is usually attached with adhesives similar to your fillets. A good bond at the root lends to a much stronger fin attachment. Areas where adhesives are used are masked off and roughed up with sand paper. Fin installation instructions for the Blackhawk on the Wildman website are very good.

 

[TRFfan]

Did you prep the fins and tube surface for your adhesive? The root of the fin is usually attached with adhesives similar to your fillets. A good bond at the root lends to a much stronger fin attachment. Areas where adhesives are used are masked off and roughed up with sand paper. Fin installation instructions for the Blackhawk on the Wildman website are very good.

Yeah, i did rough it up the body tube a little. The fins were tacked on with CA. Anyway, i sanded the tips of the fins so that they would all be equal. Here are pics of all the sides and a mockup (this isnt the nosecone i will be using).

View attachment 316707View attachment 316708View attachment 316709View attachment 316710View attachment 316711

 

[tim cubbedge]

Dang man! You used more than a little CA to tack those on! Probably would be best to tack on with JB Weld. Like retortec said, you need to rough up the fins and airframe where ever you are applying your fillets. I'd definately clean up that CA!

 

[TRFfan]

Dang man! You used more than a little CA to tack those on! Probably would be best to tack on with JB Weld. Like retortec said, you need to rough up the fins and airframe where ever you are applying your fillets. I'd definately clean up that CA!

Ok i snapped them off.

 

[retortec]

Take your time! You have invested a lot of time on a good design. You invested a bunch of money in great parts. Why not maximize you investment with good assembly techniques. A great assembly can yield unexpected performance. All your research and enthusiasm proves finishing it off great is well within your capabilities.