V2 for my L3

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
All charges will be controlled by a pair of RRC3 altimeters. I know the thinking about using two different types/brands of altimeters, but I would rather go with the altimeters I have experience and comfort with. To me there is more of a chance that I will mess up with a new altimeter than the altimeter will mess up on it's own.

The best way to describe how the altimeters will be supported is with a picture:



The altimeters are mounted to Missileworks 3D printed sleds (54 mm variety), and will be therefore supported by 2 rods. They will be held in place by lock nuts above and below on a single side of the sled, so that the threaded rod they are on can be screwed into the T-nuts in the aft CR once the bulkhead is installed (makes more sense when I get to the pics). This setup allows the altimeter, ematches, and charges to be completely prepared outside the rocket and the entire assembly loaded together.

The inner tube of the bay is a spare piece of 4.1" Magnaframe left over from my L2 build, Arapahoe-J (soon to earn a name change with a K-flight). The aft CR has 4 holes that do not go all the way through, into these was epoxied (5 min) 10-24 T-nuts. These will accept the threaded rod holding the altimeters. These do not have to pass all the way through as they will not be carrying the bulk of the load upon ejection, that will be handled by 2 pieces of 1/4-20 all thread. The roughed up magnaframe was then epoxied into the CR with Aeropoxy, a square was used to ensure that it was, well, square. The next day an Aeropoxy fillet was put on the joint.



Before gluing the assembly into the rocket a test fit was in order, with and without altimeters. Note: I will either be mounting the magnetic switches differently in the finished rocket, or I will use rotary switches. Haven't decided, but the clearances are fine for either of these solutions.



The all thread that the altimeters are mounted on have been turned into long bolts by the application of some red threadlock to the cap nuts that top them off. Note: every "permanent hardware attachment has some red threadlock in it.
 
Last edited:
With a good fit for everything confirmed it was time to epoxy the electronics bay in place. The aft CR needed to be 5 1/4" from the aft end of the bt. To accomplish this I went back to the scrap bin and cut a spacer from some pergola construction leftovers. The bay was epoxied in place with Aeropoxy, again thickened with milled fiberglass so it stayed where I wanted it.



Once that dried I had to come up with a way to do the "internal fillet" as my hand was not fitting in there. I always keep a look out every year on lab cleanup day, and scoop up any expired or unwanted lab supplies that may be of use. Turns out an "expired" 5 mL pipet aluminum taped to a 30 mL syringe of a type no one in the lab likes works perfectly for injecting this fillet. An "aft fillet" was also applied, but that was pretty easy as it didn't require any tools other than a plastic spoon, so no pics.



To better support the upper bulkhead a 1" thick ring of 7.5" phenolic was cut and notched to allow it to fit inside the bt. This was then epoxied in with some more fiberglass/Aeropoxy mix. The bulkhead was used to push this into place to ensure it was at the correct height all the way around.



With that, the body tube is nearly complete. Rail button attachment and a bunch of holes to accomidate altimeter breathing, pressure relief and shear pins are all that remains.
 
Last edited:
Thanks for the good words. It has been going remarkably smoothly thus far, but this is just the warmup to get me ready for the business end of this beasty.

Another reason not to leave Texas: you get to see Chris' fine work in person. :) Whenever we do get to launch again ! :rolleyes:

Problem is we may need to leave TX to launch again. I have launched slightly more N*s in OK this year than in TX.
 
Time for another update from the natatorium lobby.

I took an evening and setup all the soldering stuff and finished off the master bulkhead. All of my electronics bays are wired the same way with female JST connectors and the wires soldered directly to terminal blocks and potted in epoxy within the bulkhead. This protects the weakest point (my soldering) and buried all the exposed conducting bits in epoxy which should help prevent unfortunate shorts. I think the key to doing this is checking for conductivity and shorts at every step. Once the epoxy has set would be a terrible time to find out there is a connection problem.

The straight forward set were the main charge connections as these are accessible from the fore side of the bulkhead. The more problematic were the drogue compartment terminals. These had to be routed over the fore side of the bulkhead as they needed to access the donut hole. I probably could have worked out a fancier way of doing this through the tube wall, but that would have introduced another failure mode, and I want to make every effort to control as many of the things that can go wrong as I can.

Pictured are representative samples of the main and drogue attachment. For these attachments I just use 5 min epoxy.



After all of the terminals were attached it was time to put on the rest of the hardware. All of the hardware used is stainless steel, as it will all be exposed to ejection charges. The primary recovery attachments are a Forged M8 stainless eyebol and forged stainless lifting nut. A healthy amount of red threadlock was used to ensure these are tightly joined. The charge wells are made from 1/2 pvc sch40 end caps that are drilled and countersunk in the bottom for an 8-32 machine screw, and have a small hole in the side to allow the ematch through. These have served me well in charges approaching 3g (room for about 4.5g), which is on the upper end of what would be needed here.



Lastly, everything fitted in place in the tube.



Total Weight of the body tube missing only altimeter and energetics is 4 lb 1 oz. That leaves me a touch over 7 lbs for the nose and bt. Right where I had hoped I'd be.

This pretty much brings the progress up to date. I need a good round of garage cleanup, and then I'm going to start some vacuum bagging tests, so this thread will probably go stale for awhile.
 
Last edited:
Let me say for the record that my wife is very cool. Aside from being the only purple haired PTA mom I know she continues to find ways to surprise me.

Real conversation from Saturday (a well timed one too):

Her: "What do you want for Christmas?"

Me: "An Aerotech 75-6400 motor, and while we're at it how about an M650W reload for my birthday." (When asked a question like that go big or go home, right?)

Her: "Sure. I don't get it, but sure if that's what you want."

Me: :jaw:...10 sec pause for shock induced blackout to pass, then...:marshmallow:

Her: "Ah, how much is that?" (A question probably inspired by my sudden fit of awkward dancing)

Me: $xxx

Her: "I REALLY don't get it, but ok."

Yep, I married up. We don't always "get" each other, but we don't always have to.
 
Last edited:
My recent shock from the wife was when we sold my 2000 GMC Sonoma High Rider pickup, and she said that ALL the money I could spend on what I wanted, so I bought her a Springfield XD compact in .40 S&W, me a Springfield XDM 4.5 in .45ACP, a SIG 556 pistol, and the most important part.....an M1297W-P (L3 cert motor), a L1000W DMS (test flight motor, and largest I can fly on my home field), and the parts for my L3 cert upscale of the Cherokee-D. Balsa Machining and Loc got a pretty good chunk of money, at least compared to my usual yearly budget. She did ask for Christmas money which was no big deal after all we are married and sharing is part of that.
 
That upscale Cherokee is going to be epic. My 2.6" is probably my favorite rocket, just a great flier. Are you going about 7.5" for the L3?
 
That upscale Cherokee is going to be epic. My 2.6" is probably my favorite rocket, just a great flier. Are you going about 7.5" for the L3?

5.5", I thought about 7.5" but I want to be able to transport it more easily and fly it on less expensive motors. Should do something just over 9K on the M1297 according to the sim. Of course the sim doesn't take into account the FG wrap on the airframe, so it should be closer to 8500'.
 
Let me say for the record that my wife is very cool. Aside from being the only purple haired PTA mom I know she continues to find ways to surprise me.

Real conversation from Saturday (a well timed one too):

Her: "What do you want for Christmas?"

Me: "An Aerotech 75-6400 motor, and while we're at it how about an M650W reload for my birthday." (When asked a question like that go big or go home, right?)

Her: "Sure. I don't get it, but sure if that's what you want."

Me: :jaw:...10 sec pause for shock induced blackout to pass, then...:marshmallow:

Her: "Ah, how much is that?" (A question probably inspired by my sudden fit of awkward dancing)

Me: $xxx

Her: "I REALLY don't get it, but ok."

Yep, I married up. We don't always "get" each other, but we don't always have to.

Ha, nice ! That takes care of your "quid"; now aren't you a little bit curious about her "pro quo" ? :confused:
 
5.5", I thought about 7.5" but I want to be able to transport it more easily and fly it on less expensive motors. Should do something just over 9K on the M1297 according to the sim. Of course the sim doesn't take into account the FG wrap on the airframe, so it should be closer to 8500'.

That is a good size. I guess I'm surprised it will come in under 2 miles with an M in it. Should be real nice. Incidentally Mark should still have the Cherokee files he made for mine with the old school Estes logo circa the first release of the Cherokee if you would prefer that look.
 
I will be getting in touch with Mark about doing the graphics for the Cherokee and my 3" upscale of the Aries SST.
Even at 5.5" it's looking to weigh about 30lbs (Sim weight).
 
Ha, nice ! That takes care of your "quid"; now aren't you a little bit curious about her "pro quo" ? :confused:

Uh oh. Not until just now I wasn't, thanks Sam.

That came off more cold-blooded than I intended, and quite troll-like. I don't like being troll-like. Indulging each others hobbies sounds like a winning formula to me. Please carry on with the build. :) And yes, I agree, you married up. :grin:
 
That came off more cold-blooded than I intended, and quite troll-like. I don't like being troll-like. Indulging each others hobbies sounds like a winning formula to me. Please carry on with the build. :) And yes, I agree, you married up. :grin:

No worries, Sam. I took it exactly how you meant it, as a good natured bump. I will indeed continue shortly, I have A few pics from my trip to the Dallas Makerspace with Bill to cut the boat tail queued up for my next build posting.
 
The test fin went better than expected. How it was done:

I always cut out a few extra fins and choose the best one's for the actual build. In this case one of the rejects became the composite test fin. I just started vacuum bagging, and have only recently started using CF cloth. Throw in the addition of end grain balsa to lighten things up, and I was in really uncharted territory, so a test was in order.

One of the reject fins cut from 3/8" Baltic Birch Ply was lightened up considerably by cutting it into a ~1inch (bit extra on the bottom for landing stress) frame using the scroll saw. Another high quality Harbor Freight product of course.

Mass-Starting: 425 g



Mass-Frame: 182 g

The frame was then used to draw the cutout shape onto the end grain balsa, also 3/8" (a touch thicker because of the layer on the back that holds it together). Sheet really isn't the best descriptor. This is really a mat made up of end cut blocks 3/8" thick and held in place by a mat glued to the back. Strange stuff, but rather cool in use. The shape was then cut out using a curved paring knife...really easy to cut this way. Some trimming and it fits great.



Mass-with Balsa: 246 g This is the best place to count the weight savings, as even solid plywood was getting laminated, so this worked out to a 179g per fin savings, or 42% core weight. That is extra important when you consider that pretty much every extra ounce on the tail of this thing requires almost equal weight be added to the nose.

To get this whole thing bonded up the CF cloth (3K twill, 196 GSM Aerospace grade goodness from Soller Composites) was divided out using masking tape (makes it easier to cut and keeps the edges from fraying). Each side of the fin will have two layers of cloth, offset by 45 degrees. The cloth is cutout using a rolling cutter with my ever present cutting mat underneath...super easy and no pulling on the fibers this way.



This whole mess was put together using US Composites 635 Laminating Resin and medium hardener. 20-25 min pot life, so organization is a must, and of course everything (release layer, bag, sealing tape, bleeder layer) was precut. The fin was complete and under vacuum in 18 minutes. It is noteworthy that I didn't prebond the balsa into the fin. Instead I made sure to apply a liberal layer of epoxy to the inside of the frame and outer edge of the balsa before inserting it. I also brushed a thin layer of epoxy into the seams between the balsa blocks before the layer was pushed into the fin frame. The fin sandwich was held at 150 mbar overnight. That was an experimentally arrived at number. I took the system I'm using down to about 20 mbar in some tests, but the fabric appeared a little epoxy starved when I pulled out the samples. Yes, there were a whole series of tests that preceded these tests, I'm a scientist you know.



The next morning the bag was opened up and the fin pulled out. It was allowed to cure another day before I trimmed it with a cutoff disk in my angle grinder and finished the shaping with the belt sander. I wore a mask, and next time I'll wear long sleeves too...wholly crap does CF dust make you want to subject yourself to the belt sander. After rigorous vacuuming and showering I returned to scientifically test my part. To do this I bridged two bricks with it and stood my not-so-petit self directly in the middle...no failure, not even the slightest noise in fact. I then took it out in the driveway and smashed it (HARD) off the driveway at about every angle and no more than cosmetic damage. I have full confidence in fins made this way, and best of all they are still lighter than the starting plywood alone.



Mass-Final: 354 g

You can see where the core swelled a touch when the epoxy got on it and made for a raised central section. This isn't as raised as it appears in the pic, but will either require a skiff of bondo, or using it as the basis for some fake panel lines. The placement is not far off the panel lines from the real thing according to some documents I found on the interwebs. We'll see how much finishing I feel like doing in the end, but I suspect this is going to go the bondo route.
 
Last edited:
The last thing to do to bring this thread up to current is outline the boat tail progress. Some of this was done months ago, hence the green grass and evidence of swimming in the photos.

Before I cut the end off I wanted to exploit the tip to help mark off the fin slots. I tried putting a screw in the end and stretching a string to mark a line, but making it lay true just wasn;t happening. Plan B was to use a piece of straight steel as a marking guide. To do this a paper template was made, measured, and marked off into 4 equal segments. That was taped around the shoulder and the marks transferred to the cone. The steel was strapped tightly to the NC with a bungee cord (can never have enough of those) aligning one end with the mark and the other end with the NC tip. A silver sharpie was used to lay out the lines.



Like I said originally, Bob had done me a solid and marked the NC for the V2 boat tail conversion cut. Now, I could have free handed this like I normally would, but a club member, Bill Gee, let us all know that he had joined the Makerspace and would be happy to have us if guests if there was a reason. A couple emails later and I had located big ol horizontal band saw, which is perfect for the task. We shimmed the NC up with books and a miter box to keep it from rolling around, and together managed to cut both ends of the NC and none of our digits...Success!



Has a certain French Revolution feel to it doesn't it?

Of course, now that the boat tail is cut I had to mock up what I had...this bugger is BIG!



The boat tail has a wider OD than the BT. This does create a visible shelf, but that is just about the right place for the little band that is evident around the V2's "waist". I haven't taken the time to research what this was for, but I appreciate the cop out it provides on the OD discrepancy.
 
Man this thread just keeps gettin' better. So, you found that saw at the Makerspace ? Yea team ! Do locals rule or what ? :)
 
Last edited:
...Yea team ! Do locals rule or what ? :)

Yeah buddy they do! If you haven't made it over there yet you really need to, it's nerd-vana. I'm playing around with vector images as that is one of the inputs for the CNC router software, and the laser cutter there takes pdfs. I can definately see visiting from time to time.
 
Got a visit from Pyrobob at lunch time. Got the motor, reload and some Black Friday goodies too. The motor and reload have already been turned over for wrapping...I promised to look surprised.



I kept everything in the lab for the day. Having a bunch of rocket motors around didn't shock anyone. As is evident every year at fire extinguisher training, the entire company thinks the chemists are the pyros anyway...they're not wrong.
 
Got a visit from Pyrobob at lunch time. Got the motor, reload and some Black Friday goodies too. The motor and reload have already been turned over for wrapping...I promised to look surprised.



I kept everything in the lab for the day. Having a bunch of rocket motors around didn't shock anyone. As is evident every year at fire extinguisher training, the entire company thinks the chemists are the pyros anyway...they're not wrong.

Doin' it in style, Long burn!
 
Doin' it in style, Long burn!

Yep, this project is built around the motor. The M650W is just too cool, 9+ seconds of big flame and white smoke, what's not to love. Plus it hits hard enough initially to get a rocket this heavy moving safely...just a well designed beast. When thinking about what to fly it in I couldn't come up with a cooler craft than the V2. I've decided to paint it the V4 flight paint scheme. The 1/8 scale Peenemunda experience, sans Nazis, of course.
 
This is going to be awesome!

Hope so, and glad you like it. The build is basically on hold until after Christmas though. The next step requires fitting the Aeropack, and I need the motor for that. It is already wrapped, so looks like I'll get a chance to finish up the 2.1" upscale Thrustline Duster I've been using as a materials and techniques testing platform. It's gonna be sweet itself, black fiberglass over cardboard for body with CF fins (actually CF over basswood cores). The fins look fast just sitting still on the bench.
 
I have an mp3 of "Flight of the Valkyries " you could play before the button gets pushed if need it since you are short a few Nazis. Your work is really impressive and I look forward to seeing it fly. I will bring my cameras and GoPro's to the event.
 
Last edited:
I have an mp3 of "Flight of the Valkyries " you could play before the button gets pushed if need it since you a short a few Nazis. Your work is really impressive and I look forward to seeing it fly. I will bring my cameras and GoPro's to the event.

Awesome all the way around. I will probably fly this in Asa for the cert next fall. Does Marlin have a long 1515 rail? Although sims say 8' is plenty, I'd still like to give this thing some extra rail to get up to a good speed.
 
He has a trailer mounted 21 foot rail power tilted by a pair of very large air shocks supplied by an onboard compressor .
 
Back
Top