18mm Carbon Fiber screamer- The Crow 18

Got the bottom half of the mold finished, it's curing now. I think I should be able to lay up the first cone tomorrow. The boring stuff is almost over and almost time for the rocket to take shape. The only real issue I have at this point is I'm almost out of lightweight glass. Not sure if I am going to have enough for the cone. I may make a trip to Hobby Town tomorrow to pick some more up.

I had just enough glass to make one cone. The first cone is curing in the mold. I'll pop it out in the morning and see how it turned out. The small diameter is definitely harder to work on than a cone in a larger size. I think it will turn out fine, at least I hope. Since the cone has such a high aspect ratio the tip is very long and skinny. To help protect it from breaking off on landing I finely chopped some carbon fiber and mixed it up with epoxy then filled the tip up before starting the lay up. Pictures some time tomorrow.

So the nose cone is in the mold out in my truck curing on the dash board in the sun. The Raka seems to be taking a little longer in the colder temps that the West I used for the mold did. The sun should speed that up some. Last night I ordered a Perfectflite Firefly altimeter that I hope will fit along with the Telemini and its battery. If not then I will make a small sled for the Firelfy to fly solo when I fly smaller motors like C6s when tracking wont be needed. I am hoping I can pull the cone from the mold in about another hour. I'll post a picture when I do.

The cone came out pretty much perfect at least on the top side. The epoxy is still a little bit too soft for me to attempt to pull the cone out. I like to separate the mold halves before the epoxy is fully cured just in case anything were to be stuck. So far I'm very happy with it.

It is out and trimmed most of the flashing off. I'm really happy with how nice it turned out. I was expecting some voids due to the tight radius. I am a little worried that my RAKA epoxy may have gone bad. I weighed it out so I'm sure it wasn't a ratio error. It is still soft. One thing, it is significantly thinner than all other cones I have made, to keep the weight down. So im wondering if maybe its just the fact that it is not as strong and when combined with the fact that it hasn't even been 24 hours yet it seems extra soft. usually I pull them out the next morning and they feel stiffer than this... We'll see. It is very light weight, which is good for this build. My sims with estimates comes in over optimal but only penalizes me a few feet. If this one cures up nice, it will be well under my estimated weight for this part.

The cone weighs 7 grams. Much lighter than I was estimating. It's now been around 27 hours and the epoxy is still pretty soft... What do you guys think? Bad epoxy or longer cure time due to colder weather? If it isn't more cured by the time I get home from work tomorrow, I think I'll go ahead and make another one. This time I'll use my West, since the mold has cured very nicely.

I say put some heat on it and see if that makes it any better.

maxvelocity said:

The cone weighs 7 grams. Much lighter than I was estimating. It's now been around 27 hours and the epoxy is still pretty soft... What do you guys think? Bad epoxy or longer cure time due to colder weather? If it isn't more cured by the time I get home from work tomorrow, I think I'll go ahead and make another one. This time I'll use my West, since the mold has cured very nicely.

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Slow cure epoxies do especially poorly in terms of cure time when used in extremely thin layers. I agree with Max up there, hit it with some more heat and give it another day or so. 90-100*F should be plenty.

Ok, so a couple days later and this thing is curing just very slowly. I think by 7 days it should be fine. It's not just the cone itself, which is thin, its also the leftover epoxy in the container I mixed it in. They are both slowly curing. I'm thinking it has just reached the end of it's life. There is only a tiny bit left in the bottoms of the containers and I have had it for at least four years. To top it off the bottle are clear so I'm thinking it is just expired. Either way I need new epoxy so I will get some ordered. I hope it is hardened enough when I get home today that I can start working with it, trim the shoulder and test fit it. Tonight I will cut the fins out and tack them on. Then fillets sometime in the next couple days. I also need to cut the payload section from the length of tube I have.

Got the fins cut out and tacked on using my new Ultimate Fin jig for the first time. Works great and I was able to do all three at the same time using the leftover West from my nose cone. I ended up making another nosecone using the little bit of west I have left. The off color wont matter here since I will be painting the nosecone anyways. It is already more set after around 2 hours than the RAKA was set in two days. I put the RAKA cone under a shop light which I used to dry the mold release and it seems to have hardened some more. However, I am still a little worried about how thin it is so this one I made almost twice as thick. The new cone should be cured enough to pop out in the morning. I received a shipping notice on my Firefly this afternoon. Looking forward to getting it and finding a space in my av bay for it. I shaved the corners off the terminal block on my Telemini and it now fits nicely into the coupler, which is a good thing because I was worried about having a long enough payload. I think I will put a screw switch on top of the bulkhead which will be epoxied inside the bottom of the coupler for arming the Telemini, then the Telemini, the battery and then the Firefly. As of right now, without having the Firefly in my hands, I think everything should fit. Tomorrow evening I'll get at least a couple sets of fillets done if not all three sets. I should be on track to have this rocket all built and painted for flying at our next launch in February.

Yes, these jigs are very nice. Too bad they are no longer available. No more eyeballing and holding the fin til the epoxy sets up. I measured this morning and they are all right on. I did have to do a little shimming on one of the fin plates. It was leaning by about .010-.020" in the height of the plate. Folded a piece of paper and put it under the short side and that fixed it right up.

The second cone is out and I am much happier with this one. It has already cured more than the other one and with the added thickness it just feels better. Little extra weight, but oh well it still isn't heavy. There is quite a bit of fiber in the flashing near the tip so I wasn't able to easily trim it without tweaking the tip too much. Ill wait until it is harder.

Got all the fillets done. Came out nicely. The booster weighs 15 grams with fillets, pretty happy with that.

Did a little pre superbowl work on the Crow 18. The new nosecone is now cured enough for sanding. Last night with some leftover rocketpoxy from the fillets, I cut out and filled in some little voids (black spots in pic) in the cone. I sanded the seam out, sanded those spots down smooth and sanded the shoulder to a nice snug fit. Then mocked up the rocket to she how she looks, with the casing and a penny for scale. I'm getting pretty excited about flying this one! Looks like my Firefly will be here tomorrow so this week I'll be able to figure how the av-bay will work out. Now time for some jalapeno cheddar bacon wrapped hot dogs and beer.

My Perfectflite Firefly came in today. What an awesome little altimeter, especially for the price! Very tiny. For this current payload configuration, I don't think I can fit both the Telemini and the Firefly, it's just a little too short. I also ordered a AltiUno SMT this morning, and that also will not fit in with the Telemini in this configuration. So, as soon as I get some more epoxy I am going to do a longer version with a payload long enough to accommodate the Telemini, for tracking and deployment, and either the AltiUno or Firefly. This version can use any of the three, one at a time which would leave me without tracking on the two so I will be limited to C motors. Which will still be cool. I want to fly the composite D motors with the AltiUno for pyro and the Telemini doing the tracking. So I'll get to that a little later.

Can anyone tell me how much black powder there is in Estes motors? I'm thinking about half that amount will be plenty for my charges. Now just to figure out a tiny dependable charge holder...

Why not just use the Telemini?

patelldp said:

Why not just use the Telemini?

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Just for fun. I've ended up putting a lot of hours into this tiny project so i figured why not have a little fun with it. I have been wanting a tiny simple single apogee deploy altimeter anyways for other projects, and since it will fit in this size tube there's no better time. I have actually never used the Telemini for deployment, no real reason just look at it as a tiny tracker with telemetry. i will be using it on this one for deployment duties though, hopefully this month if everything goes right.

Last night I made a bulkplate for the coupler and drilled a hole for the e match to run through and another where the Kevlar cord will run through. Then I tacked it in place with 5 min and ran a tiny fillet with JB weld. I also trimmed the coupler to length and will use the rem as a shock cord anchor and thrust ring for Estes or any other motor without a built in thrust ring. This evening I coated the coupler in a thin layer of 5 min just to build up the OD so it fits snug in the booster. The top of the coupler (1/2") will be epoxied into the payload. To center up the tubes on the coupler I will tape the tubes to an aluminum angle for alignment while the epoxy cures. Then I will have a perfect fit up for nice smooth tube transitions. Going to shoot the nosecone and hopefully the portion of the fincan I will paint with high build tomorrow. Then I will just be waiting on my .050" Kevlar to arrive and I'll be able to finish the build.

Got a couple packages in the mail, chute from eRockets and Kevlar cord from 3 Dogs, very fast shipping from both. Tomorrow after work I'll epoxy the cord to my anchor and then epoxy that in the booster. I now have everything. You might notice I didn't do any primering... I was too busy this weekend so I'll do the painting this coming weekend and let it cure for next Saturday's flight.

I have been watching this for a bit, very cool!

You need to see if anyone around you has an old Aerotech F55T. Jim Urrata flew a minimum diameter 18mm rocket on one of these in 2004 in Cobleskill, NY. This was before small electronics, so it was just a rocket, a motor, and a streamer. Somehow he found it, complete with slightly bubbled paint. It was so hard to follow!

It was Estes paper tubing, a balsa cone, and thin G10 fins.

Picture 052 by Jim06911, on Flickr

That's nuts that he found it! I guess with a long enough streamer it shouldn't be too hard to spot if you scan the area. Our fields usually aren't very friendly to small rockets with alfalfa, deep furrows, corn or tall weeds trackers are pretty necessary with small rockets going out of sight. Even with the tracker, I'm a little worried about being able to spot this tiny 9" chute.

And yes, I need to find an old 18mm F. Either that or hope CTI comes out with a Pro18 line... That would be awesome!

Here is the harness and anchor/thrust ring before epoxying it inside the airframe. I Got that done tonight and also worked on getting the electronics to fit. Spent 3 hours getting everything to fit in the payload. It still just barely fits and takes a little work to get it all the way in. Once it's in everything is great and I can access the switch without to much issue. Whenever I build another version of this I will make sure and leave a lot more room so it isn't such a pain.

Following this build with bated breath Got to say it is totally cool LP rocketry at its most extreme. Arrrr

Today I got the tower for this rocket built. I also painted the nosecone neon orange. I had wanted to do a little orange on the fins to and then lay a nice clear coat over the whole thing but I just ran out of time. After tomorrow I will focus on getting a nice paint job on it. It will fly tomorrow as long as the skies clear. Last month the fog never lifter so we had to fly very low and slow only. After the last couple weeks being sunny 70+ and perfectly clear, these last couple days have been very foggy throughout most of the day, of course... So we will see. At the very least it will fly on a C6.

Couple more pictures before tomorrow's flight. Hope I can find it!!

She looks great!
Best of luck with the first flight!

Well it flew today. 2927 ft, 604 MPH and 26 g's. Not quite as high as I was hoping for but still good. It turned a little out of the tower, so I probably lost a little there. Recovered it about a 1/4-3/8 mile away. I was hoping the Kevlar cord being so bunched up would take the place of wadding or nomex but it didn't completely block the charge so the tips of the chute melted a little and stuck together so I had a hard landing which popped a component off the Telemini. Other than that overall a nice little flight!

What was the motor?

That is really cool. Way to push the envelope in the other direction!

How did the Telemini perform with regard to the telemetry?