What did you do rocket wise today?

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Five

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I got my Arch Blast from DG&A today. This is the first rocket I’ve purchased from them. So upon opening it I see the airframe doesn’t have through the wall fins. I have to cut out slots myself. I started my first slot and it doesn’t look pretty.
I have my doubts but we will see how it looks when I’m finished.
I knew I should have bought a Loc or madcow.
I pulled it off!!!👍😁👍
It’s completed 3” diameter. 59” tall. 38mm motor mount. I put a 36” chute instead of the stock 30”….its miller time.
 

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teepot

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A couple of things. It looks great. How much does it weigh? And I use a reinforced cut off wheel on my Dremel to cut fin slots. It's quick and easy. Usually nice straight cuts.
I pulled it off!!!👍😁👍
It’s completed 3” diameter. 59” tall. 38mm motor mount. I put a 36” chute instead of the stock 30”….its miller time.
 

teepot

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Todays activities included fixing some mistakes I made when I was first started building. I was ignorant. I didn't know what I didn't know. Now I know some more. The 60th rocket I built was a 4" V2. [ I was averaging 2 to 3 rockets a week back then]. When I built it I didn't have a grasp on CP. I figured just balance the rocket in the middle and it would be ok. Well that leads to heavy rockets. The 43" tall V2 weighed 85 ounces. So today I took the nose cone off and replaced it with new one. Added a threaded rod and eye nut and 5 ounces of BB's and epoxy and rebalanced it. Now it weighs 55 ounces. There are other rockets that need looked at too. I also started to put the finishing touches on one of the current projects. It will be finished tomorrow.
 

Antares JS

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More reloadable woes today. Even liberally applying Vaseline in the spots I was instructed to do so, the liner tube assembly wouldn’t go in to the point it needed to reach. Hammering it in further than flush with the end damaged the grain, and so did my attempts to push it out. I don’t know if this was because I damaged the casing in my attempts to get the last load out, or if the reload was incompatible with my manufactured-under-license hardware (a Monster Motors Reusable Rocket Hardware RMS 18/40, yes /40 and not /20) or if the age of all this stuff simply made it go out of manufacturing tolerances. Regardless, the end result was disappointing. I just threw everything away.

I’ve got plenty of expendable types to try in my Estes Phantom, so I won’t be flying a reloadable in it anytime soon. But you can bet that when I do, it’ll be with a brand-new, genuine AeroTech casing and a fresh reload, not a bunch of junk that’s been sitting in my garage for 10 or 15 years.
Per Aerotech, you can peel layers of paper off your liner if it fits in the case too tightly. I had to do this with 18/20 reloads myself. Little buggers fit pretty tightly.
 

smstachwick

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Per Aerotech, you can peel layers of paper off your liner if it fits in the case too tightly. I had to do this with 18/20 reloads myself. Little buggers fit pretty tightly.
Thank you! Good to know. I imagine it can be tricky to maintain tolerances in this size, I’m glad there’s some room for adjustment.
 

Five

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A couple of things. It looks great. How much does it weigh? And I use a reinforced cut off wheel on my Dremel to cut fin slots. It's quick and easy. Usually nice straight cuts.
I used a exacto knife. It took some time and patience and after a boat load of epoxy its nice and solid. Haven’t weighed it though.
 

Five

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A couple of things. It looks great. How much does it weigh? And I use a reinforced cut off wheel on my Dremel to cut fin slots. It's quick and easy. Usually nice straight cuts.
3.6 LB
 

cfoster3448

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Almost finished - still waiting on the balsa transition (hopefully be here tomorrow). I just fitted the paper transition I made onto the rocket and gave it a coat of paint. Will still need to cut the BT-55 (upper tube) to it's designated length (13.5") and when the balsa transition arrives, paint it and replace the paper transition that's currently on it. I've got the decals printed and ready to apply. This has been a really fun scratch/upscale build and one of my favorite rockets of all (my) time in rocketry and the kits I have purchased 15-20 years ago.
Aerobee_300_maxi.jpg
 

rharshberger

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Trying our a new nose cone recovery harness... thoughts?

Well, the weak link is the swivel by a significant amount (its 2/3 the breaking strength of the next weakest part and half of the one after that) the kevlar and eye nut have breaking strengths of 3 to 5 times their WLL's, not sure if the swivel is a breaking strength or a WLL. I would drill the end of the bolt the eye nut threads onto for a safety wire to ensure it doesn't have any chance of spinning off.
 

H. Craig Miller

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Good thought on the safety wire… As far as the week link, this is 4” fiberglass and the only thing on the swivel is a 5 lb nose cone… I could go to 1212 lbs on the swivel. The 1/4” tubular Kevlar was a matter of convenience… the fids won’t go through a smaller diameter. I believe the eye nut and swivel are rated at WLL, the Kevlar is breaking strength.
 
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rharshberger

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Good thought on the safety wire… As far as the week link, this is 4” fiberglass and the only thing on the swivel is a 5 lb nose cone… I could go to 1212 lbs on the swivel. The 1/4” tubular Kevlar was a matter of convenience… the fids won’t go through a smaller diameter. I believe the eye nut and swivel are rated at WLL, the Kevlar is breaking strength.
In that case the weak link is the kevlar, but given it will only be connected to the nosecone it should be okay. Even a 100G event will only produce a shock load of 500lbs (based on the NC being 5lbs), and all of your components are rated well above that.
 

Lee

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Well, the weak link is the swivel by a significant amount (its 2/3 the breaking strength of the next weakest part and half of the one after that) the kevlar and eye nut have breaking strengths of 3 to 5 times their WLL's, not sure if the swivel is a breaking strength or a WLL. I would drill the end of the bolt the eye nut threads onto for a safety wire to ensure it doesn't have any chance of spinning off.
I’m a novice when it comes to rocketry but I am also a 60 year salt water fishing veteran. During that time I’ve seen some large fish (some 100 lbs +) break rods or lines but have never seen a swivel failure. So I am doubting the swivel is your weak link.
 

rharshberger

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I’m a novice when it comes to rocketry but I am also a 60 year salt water fishing veteran. During that time I’ve seen some large fish (some 100 lbs +) break rods or lines but have never seen a swivel failure. So I am doubting the swivel is your weak link.
Check out the later post, the OP said that 992lbs was the Working Load Limit and that the Kevlars breaking strength was 2000lbs, therefore a conservative breaking strength for the swivel is 2976 lbs, the eye nut is even higher than the swivel, so the kevlar now becomes the weakest link as it is rated as breaking strength not Working Load Limit which is typically 1/3 to 1/5 the breaking strength so the kevlars WLL would be between 400 and 650ish lbs. I deal with weakest link analysis in my job every day between being a truck driver and a Load Securement Instructor as well as being trained in basic crane and rigging.
 

Cape Byron

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Did a little work on the new five fin tentatively named Munun Wambad, "the Big Wombat".

Hand cut TTW fins from 2 mm Hoop Pine ply.

DSCF8936 (FILEminimizer).JPG


Then a basic get together of parts to make sure they would fit in our standard kit box (they do).

DSCF8937 (FILEminimizer).JPG


Our first 24 mm proto. I'm so expectant excited.
 

jqavins

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(I imagine) it's good for heavy rockets and low altitude flights. I599 for a shakedown, then a CTI L585 to really put it up there!
 

mjremijan

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Baby Bertha build. Painted Elmer's wood filler onto the fins and set them up to dry. Never done this before so it'll be interesting to see how it turns out. After sanding the 1st coat, is it typical to do another coat?
 

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jqavins

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Baby Bertha build. Painted Elmer's wood filler onto the fins and set them up to dry. Never done this before so it'll be interesting to see how it turns out. After sanding the 1st coat, is it typical to do another coat?
Sand, then repeat if necessary.
 

neil_w

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Baby Bertha build. Painted Elmer's wood filler onto the fins and set them up to dry. Never done this before so it'll be interesting to see how it turns out. After sanding the 1st coat, is it typical to do another coat?
A common (but not the only!) approach would be to apply filler/primer after the CWF, sand most of it off, and then touch up remaining bits as necessary. *Usually* you would not need to immediately apply a second coat of CWF unless (a) you oversand it, exposing too much bare wood, or (b) there are some really obvious problems of some kind.
 
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