2.2 tomach min dim

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The_Quacken

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Hey all,
so recentley due to my weakness for buying new kits I picked up a 2.2 inch tomach from wildman rockets at NSL west. starting this build I assumed it would be a relatively simple project but as with everything it creeps up on you. after my experience with the 29 minimum diameter blackhawk I had on motor deploy which I instantly sent to the great flying field in the sky I knew I wanted to be a lot more careful. ofc by the time id ended up on McMaster I was already doomed😜
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(my soon to be new rocket next to my dearly missed old minimum diameter)

54 is a nice size due to price of engines as well as being able to fit tracking gear being well balanced. after plenty of time spent in openrocket making a way more complicated internal design than probably necessary i came up with the internal design.
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For the nose bay I made a custom setup using the wildman threaded aluminum nose piece as a nut to hold the all-thread into the nose bay. the tracker and battery location will be figured out once everything is built. i've been told a lot to keep metal away from tracking so to get the absolute best possible results out of the eggfinder I have I was planning on using nylon all-thread as its not too expensive and seems strong enough.
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the e bay is pretty standard. im only planning on using a single quantum altimeter for deployment due to space constraints but otherwise nothing special. the motor retention however is where I had the most design trouble. I wanted to be able to switch between any 54 motor and to do so quickly at the field. the solution I came up with is a set of 6 threaded rods of different preset lengths ( unfortunately the 6xl cases don't fit well) and a bulk plate that I could take out to thread the rod into. this bulkhead with the correct length of rod would then be butted up against a glued in retaining ring and Id use thumb press rivets to retain it in place. then the motor could be screwed in. this solution seems to work the best and provides good repair ability and flexibility while at the same time should be plenty of positive retention.
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I know I probably explained it badly but basically the green would be removable and pinned in place via push rivets and magenta would be permanently glued to the motor tube. the dotted line item represents the threaded rod that would go into the motor and the grey is the motor in this case showing a full 54/2800 case.

hopefully when I start putting everything together it'll work out as its a very tight fit. as it stands I have about three inches of space for my drogue which is not much (see photo below) but all things considered it should work ok.
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this is mostly it for planning anyways. as for altitude open rocket says 21,500 on an L1090 but rasaero says 24,200 so ill say i'm aiming for 23,000. no clue where Ill find the waiver for that with NCR's fire restriction lol but hopefully the rains will let me fly this one day to its full height. ive been a little hesitant to start with all this complicated planning but i have gotten some work done on the E bay.
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gluing the sled in


overall a very slow start to the build. that said shout out to Jesse from modelrocketguy.com for helping me feed my rocket building problem and being super helpful. more to come soon hopefully
 
image.jpgHard to understate how tight this will be with a full 54/2800 case. The light space is the entire area for motor retention plus drogue recovery. Man this makes me miss my 4” rockets lol
 
how much overlap is truly required for the coupler to be safe? I know the rule of thumb is 1 cal but realistically is it so much less safe to have it at .75 cal of overlap? realistically anything i can do to move weight forward and provide room is a win as long as its safe. any opinions?
 
I did head-end dual deploy on mine. Didn't have a lot of room to spare, but enough. I had sized it to take the CTI 6GXL motors in the aft section.

Australian Rocketry site is currently down so I can't show you anything. The rocket was launched on another flight, by accident, before I had the ground station booted ☹.
 
I did head-end dual deploy on mine. Didn't have a lot of room to spare, but enough. I had sized it to take the CTI 6GXL motors in the aft section.

Australian Rocketry site is currently down so I can't show you anything. The rocket was launched on another flight, by accident, before I had the ground station booted ☹.
thanks for the info! Maybe I’ll look into shifting the components so it could one day fit an engine like the k370 or maybe some of the big cases from Loki. Alternative sine the booster is basically a bit of coupler a tube and fins it’s also possible to make swapable boosters down the road. Maybe a Loki 54/4000 case??
 
after a lot of messing around i found I can fit 6xl cases by extending the back of the rocket an inch.... maybe. it still needs to be stable ofc and im cutting the margins sorta short by doing that if I keep the fins where they are. basically my thinking was to use a 1" fiberglass or possibly aluminum spacer on the back of the larger cases. alternatively I just permanently glue on an extra inch to the back of the tube. not sure how that will hold up without a coupler. if i fiberglass the fins I could also externally reinforce a joint like that.
 
If you don’t need the whole av bay you could recess the drogue end to give you more room for recovery gear.
 
View attachment 583959Hard to understate how tight this will be with a full 54/2800 case. The light space is the entire area for motor retention plus drogue recovery. Man this makes me miss my 4” rockets lol
On a 54 MD to 23k, I would skip a drogue and leave enough space for motor retention and some kevlar cord
 
On a 54 MD to 23k, I would skip a drogue and leave enough space for motor retention and some kevlar cord
I’ve always been nervous about drogueless and it seems like it would fall very fast. I’ve had a few flights zipper quite badly. I’d want to find some way to minimize the stress from the main opening. Maybe a deployment bag or similar I’ll look into it
 
Used ca to glue on the extension, broke it cause I did a bad job, and have now re done it image.jpgB3FEAB83-F479-4108-9ECB-55ADFD88CF72.jpeg
The old join vs the the new join drying with a big aluminum ball on top)

This should allow me to fly almost anything except the 54/4000 ofc.
As for my dreams of flying the 54/4000 I came up with a rocket from messing around with this one in open rocket that rasaero says could go to 48k 🤩😁
But that’s a project for a more experienced and richer me lmao
 
I’ve always been nervous about drogueless and it seems like it would fall very fast. I’ve had a few flights zipper quite badly. I’d want to find some way to minimize the stress from the main opening. Maybe a deployment bag or similar I’ll look into it
I doubt the shock of the main opening would cause a zipper. Unless you have a ton of noseweight the assembly should be falling flat. A rocket of this size probably descends around 90fps drogueless.
 
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I doubt the shock of the main opening would cause a zipper. Unless you have a ton of noseweight the assembly should be falling flat. A rocket of this probably descends around 90fps drogueless.
Ok that seems like a pretty reasonable speed. The nose shouldn’t be terribly heavy, just a 2s 750 lipo and a tracker + payload and e bay stuff. Probably not heavier than the motor tube
 
I found this weave that I think I’m going to do a layup with. It’s a carbon Kevlar and it’s really thick so I’ll probably do only one layer. I would love to say I have a good reason but I just think it’ll look very coolC44E50B9-334E-41E7-84EF-A008A525EDD7.jpeg
 
Now onto the most fun process! Hand shaping bevels!!! Especially when I’m actually trying to get them semi precise
 
Fun beveling
 

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So probably a poor decision but I tried to glue one of the fins on
 

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All the fins have been glued and now for a short hiatus while I’m at a different house. I don’t think the fins are on straight despite my best efforts but it is what it is
 
well, ive changed it to be head end deploy. basically i could squeeze 1-3 thousand feet out of every motor this way so I thought it was worth it. additionally i think im going to build a tower as well. its not gonna be super performance but the thought of cutting 6k of its potential maximum altitude hurts my soul
 
ok im finally done messing with the design heres the openrocket
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I find the side by side of this with the first iteration to be very funny

the nose is going to have a parachute + cupped streamer as a drogue. The motor retention has shifted to friction as there is no deployment charge that will be pressing on the casing. the av bay is going to be held in by 12 push rivets which should absolutley be able to handle the deployment forces as they each have at least 75 lbs sheer (some sources say closer to 120 depending) which gives me well over 1k lbs.

the 54 nosecone actually has an obscene amount of space so this all should fit somewhat easily even if packing will be a nightmare. definitley will need ground testing to make sure it all works. i plan rn to have a floating charge as neat the tip as possible which should guarantee everything is pushed out of the nc cause im not sure I trust the inertia of the nose cone to get the job done.

hopefully it should be ready to go and scream on some L's. i want to fly this at balls so hopefully its ready and tested by then.
 
During another sleepless night I learned to make soft shackles out of standard 12 strand Kevlar. I’m pretty confident this will not be a failure point. Splices are stupid strong and this is technically 4 strands of Kevlar so it’s theoretically 4 times as strong but practically it’s more like 2-3x strength386CFD52-CB23-4E93-ADAC-F1D375D7A521.jpeg
 
All the fins have been glued and now for a short hiatus while I’m at a different house. I don’t think the fins are on straight despite my best efforts but it is what it is
Sorry to rain on your parade, but minimum diameter vehicles really need the fins square and true to the airframe to prevent coning. How far off are they?
 
Sorry to rain on your parade, but minimum diameter vehicles really need the fins square and true to the airframe to prevent coning. How far off are they?
I mean… a little? My brain is saying they’re off but it’s really not by a lot I don’t think. I’m very much considering trying to re do them but I don’t want to very much for obvious reasons (lazy) but at the same time dont want to shred or cone

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the fin that was bothering me broke off lol so i fixed it an fillets are applied. all the parts should be on order and this thing should be ready to fly soon. i think the only thing im missing is some hardware parts to attach things like recovery
 
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