3" min dia rocket

I saw one of the new long burn Aerotec's motors a couple of weeks ago,
75mm M650, and was able to order one. So now I need to build something special for it. The plan is to make a 3" rocket the same way I did my 54mm min dia rocket https://www.rocketryforum.com/showthread.php?t=23810
I'm strating on the first of 2 tube layups today. I'm going with 5 wraps of 5.7 oz carbon. The rocket should be about 64" long when done. If there is any step, that was not clear, in the 54mm build thread that you want to see or know more about let me know.

Tony

Just off the top of my head I'd say beating your 29K is likely. Especially with that minimum of a diameter, and that long of a burn.
Nice CF work on the 54mm......
Will look forward to the pics on the 75mm.....both build and flight!

This sounds like a neat project, and it should go incredibly high

What's the expected altitude? 25k or so?


(it is only a baby M after all...)

Come on Cjl, baby M? It will get much more alt then the M1315 in a 75mm rocket and the M1315 is what, one grain less then the largest 75mm motor?

I think this will be awesome! Where did they demo it? I saw the 98mm one... I was thinking about using one of these in my competitor 4 kit...

Might wait a while though because I do eventually (could be a LONNNGGG time, or maybe just a year... could build it alongside my arliss bird for XPRS 2008) plan on doing the same thing, a 3" rocket for the M650... Wont be super high performance but anything this small will get some serious alt... Gonna play it safe and simple and probably just use a performance rocketry 3" CWFG airframe (covulate wound fiberglass airframe) with some 1/8" G10 fins that are tip-tiped with 2 layers of CF... I thought about making CF tubes but this would be easier and having a glass airframe is nice because then I can put the tracker in the bay as well...

Cant wait to see this thing... Gonna fly at LDRS (thats a little soon tho, doubt it), or maybe XPRS?

I think Ill be at both of those, would love to see it up close and meet you...

Tony,
I have not seen you fly a commercial motor in years! Looking forward to watching this one.

Geoff

I was able to do both body tubes yesterday. Both of them are 5 layers of Carbon fiber.
ID 2.967
OD 3.116
Wall .064

23.25" long
173 g Carbon fiber
177 g Epoxy
15.053 g per inch

26" long
183 g Carbon Fiber
209 g epoxy
15.076 per inch

Tony

So you now have 49 1/4" of BT that weighs only 1 lb. 10 ozs.!!
eeeeexcellent! (rubbing hands together)
Good start Tony.......:rock:
Any sims on the total empty weight?

-Chris

Not sure how high it's going to go yet. I "dial in" rocksim as I go. I saw the 98mm long burn at Dairy Aire and the 75mm M650 at Mudrock. I had heard they were working on the 75mm long burns and I liked what I saw. It's been almost 3 years since I've flown a commercial motor. I'll be flying this rocket at XPRS this year. And you can put radio trackers in all carbon rockets. You just won't have a signal until apogee. And if you don't get a signal at apogee then things didn't go as planned and a shovel will be more useful then a tracker. I hope to start turning the nose cone plug tomorrow. I'm using the same '100k' design like on the 54. Attached is a photo of the body parts.
Tony

The reason my transmitter wouldnt work is that its a GPS unit so it needs a constant flow of RF and also it cant be put in the chute bay, has to go with the electronics. So again it wouldnt get the signal at apogee...

Awesome, what day do you expect to fly it at XPRS? Ill be flying my competitor 4 at XPRS, probably on a J on saturday then a big sparky L sunday. My dad will also be going for his L3. I will have to see how I like the looks of the M650 but I may burn one in October... I am looking into some faster loads though, would like to push it supersonic and I think both the sparky L and the M650 will be a bit under mach...

Jordan. I was not thinking in terms of GPS..you got me there. I'll fly on Friday if the weather is "right".

Tony

I see, well I dont know if Ill be there all of friday but maybe Ill catch the flight... I am pretty sure there will be a few M altitude attemps soon, that 98mm one could put a 4" rocket REALLLLY high up there I would think...

The Aerotech M750W is a 91% M compared to the CTI M795 which is a 98.9% M. Which one do you think guys might use to set a new record? Now with 75mm long burn motors we can see if a smaller diameter has a shot at it. Greg Fannin did have the M record at 33,713 using an AMW M2500 motor. The current M record is 35,300 with the CTI M795. It will be interesting to see if you can finesse a 75 mm 'baby' M long burn higher.
Tony

Ahh I didnt know that CTI load was a bit more impulse.. But I saw Gregs launch pics and that was pretty amazing! But that M is a good bit larger then the M650W... Perhaps if aerotech made a moon burn load for the 75/7680 case you'd have a shot.

Here's some photos of making the nose cone blank

The diagram with measurements every inch

Starting with a chunk of mahogany

Turned down in steps

Sanded out

first coat of primer


Do these photos bug anyone or do you guys like them?
Tony

I like them. I prefer the embedded photos over attached photos any day.

Nose cone looks nice Tony!

It looks like you used autocad to do the nosecone dimensions. Is that true?

How did you come up with those dimensions for the nose cone?

jraice said:

Come on Cjl, baby M? It will get much more alt then the M1315 in a 75mm rocket and the M1315 is what, one grain less then the largest 75mm motor?

Click to expand...

It's 5,964Ns. That's only a 16.5% M. That counts as a baby M IMO...

True but my point is considering its a 75mm minimum diameter rocket, that it is a fairly large (not baby) 75mm motor... But I am looking forward to see what really can be done with a 3" rocket and a baby M as well

It looks like you used autocad to do the nosecone dimensions. Is that true?

How did you come up with those dimensions for the nose cone?

Click to expand...

We don't need another war on TRF. So heres the subject change... again.

nevermind...

Ian, A fellow rocket buddy of mine has a custom wood shop. Hence the Mahagony for the blank. It turns fast and finishs up nicely. As for the design..It came from the group project "To100K". A couple of the guys did some research as the the best nose cone design for what we were doing. O-give and conical did not far to well. Anyway they came up with the design and my wood shop buddy prints up the full size drawings for me. I don't know what 'cad program' he uses. He did give me an old copy he had, but I have not had time to play with it yet.
Tony

Tfish said:

The Aerotech M750W is a 91% M compared to the CTI M795 which is a 98.9% M. Which one do you think guys might use to set a new record? Now with 75mm long burn motors we can see if a smaller diameter has a shot at it. Greg Fannin did have the M record at 33,713 using an AMW M2500 motor. The current M record is 35,300 with the CTI M795. It will be interesting to see if you can finesse a 75 mm 'baby' M long burn higher.
Tony

Click to expand...

The AT M750W is a 76% M, vs. the 97% M795 from CTI. And the Isp is much lower than CTI's (~180 vs ~210). The M750 also weighs more at liftoff, but less after burnout.

Tony:

Did you sand down all the steps to a radius by hand? Or was there a gouge and tool rest setup in between the step turning and sanding?

Very neat work....

-Chris

Darkhelmet. Thanks for the correction!

Chris. I have a metal late so there not much free handing going on. Once I turn the steps into it, I then go back and set the compound rest to a couple of degrees and knock the tops off the 'steps'. I then use 60 grit by hand to smooth it all down. then some 220 grit and then a few coats of primer fill any imperfections. From here I make the mold similar to John Cokers method https://www.jcrocket.com/nike-asp.shtml 2/3rds way down page.
Tony

Ahhh! Ok...I agree it's much easier to turn the controls on the compound than it is to wittle it by hand.
John Coker's building techniques have always amazed me. Have yet to make a NC in this fashion, but now you definitely got me wondering. Got some popular size nosecones coming up and that might be just the ticket. Thanks.

Good luck and keep the pics coming
-Chris

Chris, I have bought regular plastic nose cones and made molds from them. Just something to think about. I did layup half the nose cone mold yeaterday. I will post some photos later.
Tony

So how exactly is the cone made, I am sure you will be posting pictures... Is that wood the mold? Or do you use that to make the mold?

And after making the mold, what do you put inside of it to make the cone release and have a smooth surface?

I believe your 54mm bird had a CF cone made similarly? It looked very cool!

Jordan, "That wood" is the blank used to make the mold.
Below is the blank in the board getting ready to get glassed. Any space between the blank and the board needs to be filled with clay. It then gets waxed and then a coat of the TAP plastics PVA mold release. The PVA dries quick and forms a water soluble film.



shows the space between the blank and the board filled with clay. Then waxed and a coat of PVA aaplied.

Shows the first half of the mold with 10 layers of 6oz glass. The edges are not wetted out becasue the mold edges will be cut later.

The first half popped off the board. Now I need to glass the exposed half now.

Tony

Wow!.......Have I been living in the dark ages.
And to think that I've been turning and glassing (and hollowing out) Balsa nosecones all these years! Sheesh! So as to make the hollowing out part more simple, I started turning foam on a center post. It was somewhat easier to hollow out, but still tedious and time consuming.
Seeing how I have a bunch of 3" nosecones I have to make, I just can't think a better way of doing this.
So....I have some poplar I am going to glue and clamp up to turn the nose out of, however I noticed that you used Mahogany. Was there any particular reason why or was that what was just on the shelf at the time? I would imagine that any hardwood would be ok, but then it only takes a moment to ask.
Thanks again.....
-Chris