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Mach 1 Warhead Build Thread

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_kestrel_

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I haven't done any dual deploy rockets and wanted to start with something that could fly on smaller motors to get some experience at a lower cost/flight. I have also wanted to build a fiberglass rocket. A few months back, Mach 1 had their Warhead kit on special for 20% off and it seemed to meet most of my criteria except, of course, it wasn't a dual deploy rocket.


The deluxe version has a 5:1 fiberglass nosecone so there should be enough room to modify this rocket to head end deploy. I didn't want to try to cut the body tube to make a switch band so I ordered a 1" piece of coupling and will build a switch band free AV bay.

I had a little bit of work done on this before starting this thread. I'll post up what I have done so far but future updates may be a bit slower due to, well, life.
 

crossfire

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I haven't done any dual deploy rockets and wanted to start with something that could fly on smaller motors to get some experience at a lower cost/flight. I have also wanted to build a fiberglass rocket. A few months back, Mach 1 had their Warhead kit on special for 20% off and it seemed to meet most of my criteria except, of course, it wasn't a dual deploy rocket.


The deluxe version has a 5:1 fiberglass nosecone so there should be enough room to modify this rocket to head end deploy. I didn't want to try to cut the body tube to make a switch band so I ordered a 1" piece of coupling and will build a switch band free AV bay.

I had a little bit of work done on this before starting this thread. I'll post up what I have done so far but future updates may be a bit slower due to, well, life.
I have built and flew a number of rockets with out a switch band with no problem.
 

_kestrel_

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First step to converting the Warhead to a HED rocket, replacing the 1/4"-20 screw holding the metal tip to the nosecone. Unfortunately, I didn't have a Phillips screwdriver long enough to reach the screw. A quick 20 minutes with a set of calipers and some 3D modeling and I came up with this:

1599959878295.png1599959908427.png

I had ordered some 1/4"-20 stainless steel eyebolts from Amazon. I just needed to get a tool deep into the nosecone to tighten the eyebolt into place. Back into CAD and a few hours later I had this:

1599960142889.png 1599960175697.png

I wasn't sure if the 3D printed tool would hold up but it did and the metal tip is back in place with the eyebolt holding it on.
 
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_kestrel_

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On to the ebay design. I wanted to fit an RRC2L into the coupler that came with the kit. I'm not going with redundant electronics for this build. I'll save that for my upcoming Level 2 build. I needed to get the ebay laid out before I could start bonding all the parts together. I placed an order with McMaster Carr for the stainless steel hardware I'd need, 10-32 threaded rod, stainless steel washers and stainless nyloc nuts. I also threw some 9-volt battery holders in with the order. I ordered the RRC2L and some screw switches from Missleworks. I rounded out the rest of the needed components from Amazon; 18 gauge silicone wire and some 1/4"-20 stainless lifting nuts.

One of the best features of the McMaster website are the CAD models of nearly everything they sell. I downloaded the models of all the hardware and modeled the rest of what I needed.

1599967979581.png

Back to the 3d printer for the sled.

1599968091450.png 1599968066753.png

A little bit of soldering and some zip ties gives me this:

1599968145542.png 1599968161027.png
 
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_kestrel_

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I had ordered some bulkheads from Mach 1 but decided to go a different way. The G10 bulkheads weighed in at 42.7 grams. I thought I could do a little better. The bulkheads needed to be drilled for the 1/4"-20 eye nut and bolt, the two 10-32 threaded rods, a 6-32 hole for the charge well, and a hole for a MissileWorks sealing well nut. Back into CAD and CAM for a bit then out to the garage.
1599973734684.png


I started with a 4"x4"x1/4" piece of 6061-T6 for each bulkhead. One side is faced and flipped over. I used a trick from Youtube and fixtured the bulkhead using tape and superglue. After machining, the bulkheads went for a ride in a vibratory tumbler to deburr.

ezgif-7-e6bbcc07c312.gif


Each of the bulkheads in aluminum were under the weight of the G10 part.

al_weight.jpg

The ebay components are all done except for charge wells. I saw a post recently by cwbullet (https://www.rocketryforum.com/threads/3d-printed-ejection-canisters.161632/) in the 3d printing forum for printed charge wells and will give that a try.
 
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rfjustin

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Looking good! You are on the right track adding the switch band. If you don't use the switch band, the coupler will jam up into the cone when the drogue charge goes off. When I ran into the issue, I added a small piece of coupler on the inside of the cone, just in front of the avioncs bay coupler. That prevented the avionics bay being jammed forward.
 

_kestrel_

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... I added a small piece of coupler on the inside of the cone, just in front of the avioncs bay coupler. That prevented the avionics bay being jammed forward.
Good timing on your post. I was going to ask if I needed anything in the nosecone to restrain the ebay. I have a section of coupler in the body tube to keep the shearpins from carrying all the load during boost. I'll machine a retaining ring out of one of the unused bulkheads
 

rfjustin

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Good timing on your post. I was going to ask if I needed anything in the nosecone to restrain the ebay. I have a section of coupler in the body tube to keep the shearpins from carrying all the load during boost. I'll machine a retaining ring out of one of the unused bulkheads
If you have the switch band in play, you should be good to go. Other pieces should not be needed.
 

_kestrel_

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If you have the switch band in play, you should be good to go. Other pieces should not be needed.
Nope - no switch band for this build. I'll use a section of coupler in the body tube and a retainer made from a modified bulkhead in the nosecone. Thanks for the tip.
 
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_kestrel_

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I followed rfjustin's advice and machined out one of the G10 bulkheads I've got to act as a stop for the ebay in the nosecone. It only took a few minutes on the mill to do and if it saves a drogue-only descent it will be worth the minimal effort.

nosecone_stop.jpg
 

_kestrel_

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Ok, next few steps. I took some time this morning to bond the top centering ring and shock cord to the MMT. This is the first time I've used System 3 T-88 epoxy for a rocket. Still too early to form an opinion but I do like that the instructions give mixing ratios by mass, 1:0.83 resin to hardener.

mmt_1.jpg MMT_2.jpg

I really like using my 3d printer to make fixtures and jigs to make tasks easier. I try to avoid having issues to fix after epoxy has cured. The fixture for the top centering ring places the CR at the right distance from the bottom of the tube, I did this to avoid any surprises when it is time to attach the motor retainer and it holds it square to the MMT. Truth be told, I'm also trying to use up this roll of purple PLA. It and my printer haven't ever gotten along - I've tried tuning in the printing with this stuff and never gotten it any better than a blobbing, stringing mess - fine for fixtures but not good for anything that needs to look even remotely decent.

I also got the short piece of coupler put into the body tube using (surprise) a fixture that made sure the part went in square and to the right depth.

fixture.jpg bodytube.jpg

This build is going quicker than expected. I'm hoping to have this ready for after harvest this fall. I'll have to figure out what to put in it for the maiden flight. It will take a higher impulse G to get it off the rail with a safe speed, maybe a G125? Or I could hit it with a hammer for the first flight, I have a H283 DMS motor that would push this upwards of 1700 feet with a 67 ft/s speed off an 8 foot rail.

*edit* - spelling
 
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_kestrel_

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Made some progress on the Warhead. I epoxied the ebay stop that was made from a leftover bulkhead into the nose cone using T-88 epoxy. The purpose, as rfjustin pointed out to me, is to keep the ebay from sliding up into the nose when the drogue charge goes off.

ebay_stop.jpg

I also got the mmt into the body tube. I left the rear centering ring off, it is a 38mm tube in a 3" rocket. There is plenty of room to do internal fillets without having to inject them. I added some chopped glass to the epoxy, not that it needed any extra strength. I just wanted to see how the T-88 behaved with the added fiber. I'm sure there a lot of opinions on adding chopped fibers to epoxy - is it necessary as you move up to higher power rockets?

mmt.jpg

I probably went a little overboard on the epoxy. Definitely could have used less.
 

_kestrel_

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I also got lines marked for the rail buttons and to help me line up shear pins and the ebay vents. I have a simple tool that I use to get the center marked:

centerline_3inch.jpg
centerline.jpg

Put the pegs on the tool into the fin slots, rotate it until it is tight, and mark the center. Then a quick line drawn with a piece of aluminum angle. Getting the fins in will be the next step.
 

crossfire

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Ok, next few steps. I took some time this morning to bond the top centering ring and shock cord to the MMT. This is the first time I've used System 3 T-88 epoxy for a rocket. Still too early to form an opinion but I do like that the instructions give mixing ratios by mass, 1:0.83 resin to hardener.

View attachment 431561 View attachment 431562

I really like using my 3d printer to make fixtures and jigs to make tasks easier. I try to avoid having issues to fix after epoxy has cured. The fixture for the top centering ring places the CR at the right distance from the bottom of the tube, I did this to avoid any surprises when it is time to attach the motor retainer and it holds it square to the MMT. Truth be told, I'm also trying to use up this roll of purple PLA. It and my printer haven't ever gotten along - I've tried tuning in the printing with this stuff and never gotten it any better than a blobbing, stringing mess - fine for fixtures but not good for anything that needs to look even remotely decent.

I also got the short piece of coupler put into the body tube using (surprise) a fixture that made sure the part went in square and to the right depth.

View attachment 431563 View attachment 431564

This build is going quicker than expected. I'm hoping to have this ready for after harvest this fall. I'll have to figure out what to put in it for the maiden flight. It will take a higher impulse G to get it off the rail with a safe speed, maybe a G125? Or I could hit it with a hammer for the first flight, I have a H283 DMS motor that would push this upwards of 1700 feet with a 67 ft/s speed off an 8 foot rail.

*edit* - spelling
DMS H219T would work well.
 

REK

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I followed rfjustin's advice and machined out one of the G10 bulkheads I've got to act as a stop for the ebay in the nosecone. It only took a few minutes on the mill to do and if it saves a drogue-only descent it will be worth the minimal effort.

View attachment 431555
I recommend getting rid of the ring and use the coupler stopper instead. That looks like something your chute could snag on to and will not allow the chute to deploy or it could damage the chute on deployment.
 

_kestrel_

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I recommend getting rid of the ring and use the coupler stopper instead. That looks like something your chute could snag on to and will not allow the chute to deploy or it could damage the chute on deployment.
There is a very smooth fillet of epoxy on the back side. Should present little to no resistance to the chute. I appreciate the comment though.
 

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There is a very smooth fillet of epoxy on the back side. Should present little to no resistance to the chute. I appreciate the comment though.
Test it just in case, give it a good yank to simulate an ejection and hopefully the chute slides out without any issues.
 

crossfire

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I have done a switch band only 1/4" Wide it works perfect. Still room for vent and switch holes.
 

_kestrel_

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After thinking about the comments on the chute hanging up on the nosecone ebay stop, I busted the Dremel out with a sanding wheel. Five minutes and a fair bit of dust (I was wearing a respirator) and the stop has a VERY smooth transition to the nose cone. It is nicely radiused into the nose. I'll ground test with the chute and nomex blanket to get charge volumes and to make sure the chute deploys cleanly. No pictures because externally it doesn't really look any different.

I had time today to get the first fin tacked in place.

fin_jig.jpg

All mating surfaces were cleaned with denatured alcohol, sanded with 150 grit, and cleaned again with denatured alcohol. The fin jig is 3d printed and then clamped in place. I made sure to clean up the aft end of the fin and mmt to avoid issues with the rear centering ring. The T-88 is slower curing but I hope to have time this evening to get the second fin in place.
 

_kestrel_

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All three fins are in now and I have started on the internal fillets. Plenty of room to do this with a popsicle stick. First set is in and curing, two more sets to go.

internal_fillets.jpg
 

_kestrel_

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Before I started on the fillets, I took a shot of the rocket all together

mocked_up.jpg

The rocket is 32" tall and 3" diameter. I'm starting to get the sim file finalized in OpenRocket. I started with the sim file from Mach 1 as a first step, before I started to modify this for head end deploy. Once I can get the final weight and CG, I'll run the final sims. It is looking like it will be a bit over 1600 feet on the Aerotech H283 38mm DMS motor.
 

Donnager

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The rocket is 32" tall and 3" diameter. I'm starting to get the sim file finalized in OpenRocket. I started with the sim file from Mach 1 as a first step, before I started to modify this for head end deploy. Once I can get the final weight and CG, I'll run the final sims. It is looking like it will be a bit over 1600 feet on the Aerotech H283 38mm DMS motor.
Mine has only flown the H-115 Dark Matter so far. I'd suspect it went 1400-1500' or thereabouts.

It's a cool rocket, I bought it to fly anything I wanted to go fast on a 38mm, although the H-115 is a 29.....

Cropped image from the background of another pic..... I didn't put my decals on stock.
CROPIMG_0433.jpg
 

_kestrel_

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Mine has only flown the H-115 Dark Matter so far. I'd suspect it went 1400-1500' or thereabouts.

It's a cool rocket, I bought it to fly anything I wanted to go fast on a 38mm, although the H-115 is a 29.....
I like the blue and yellow! I have the color scheme figured out for mine - more to come on that later. Just curious, what size chute did you go with on the Warhead? I am using the sim for a guideline, but I appreciate real world info. The sim is telling me about 19 ft/s on a Top Flite 36".

I didn't have much time to work on rockets the last few days. I ordered some carbon paper from Amazon and marked lines for the fillets (first time). I've got to say, that was WAY easier than how I have been doing it. I had been using a Sharpie on my filleting tool and transferring that to the rocket. The filleting tool is a simple ball-end tool that is similar to a cake decorating fondant tool. The fondant tools look to work well but this one cost me 18 cents worth of plastic to print. I sanded the ball and coated it with CA to get it as smooth as I could.

fillets_marked.jpg

I'll mask off the fillets next, clean with denatured alcohol, sand, clean again, and do the external fillets. I have a few choices for the fillets; 30 minute BSI with about 5% colloidal silica to thicken, the T-88 with colloidal silica, or Rocketpoxy. I'm not really worried about the strength of the joint - the rocket already has internal fillets at the MMT and at the body tube. The BSI cures faster and I could get all 3 fins filleted in an evening. Here, I'll open up a can of worms and ask what epoxy should I use? :D
 

Donnager

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The sim is telling me about 19 ft/s on a Top Flite 36".
I used a 36" on a chute release. It worked great, and would be where I'd start.

I'd have no issues cutting the size down at our site if I had no chute release/altimeter control to as small as 24", but, I don't mind rash on the fiberglass stuff, and our field is pretty soft. It would hit the ground pretty hard on a 24.
 

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