Min Diameter drag racer

Right now I'm in the worst phase of building a rocket... Waiting for the parts. However I did manage to come up with a name, I decided to keep the 'MD-38' that my dad and I have been calling it, but I added a part. Now it's the MD-38 Sky Punch, and it'a official, even ordered the decal from stickershock today.

In other news, my dad had me order him a Blackhawk 29 with the DD upgrade (because I'm the one with the wildman club membership), so now he can have a min diameter as well. Too bad he can't participate in the drag race that mine will take it's first flight in.

So this project will be tower launched, so I might as well do the build for that too in here. The tower is something I can start working on tomorrow but at least I can talk about it.

The other day my dad and I found 4 lengths of aluminum conduit about 15' each, in the garage. I will cut one of those into three 5' lengths to use as the launch guides. They will be sanded smooth for minimum disturbance to the ascent of the rocket

The blast plate is going to be just a steel plate slid underneath the structure.

The tower support structure will allow the conduits the be adjusted for different diameter rockets. The actual design is still being worked out, although if have a good idea of how to do it.

Mailman came today. Brought this


The extension is so I can put the I800 in it for the drag race that prompted this build.

So I thought I would further update this today.

UPS came today as well and dropped off parts from PML. Now I have a body tube, coupler tube, bulkheads, retainer, parachute (although it's too big, gonna get a 24" tomorrow), and an eyebolt.

So I thought I would also start working on the bulkhead/coupler assembly that will make up part of the av-bay.

Now obviously the eyebolt I have is way too long

That right there would take up half the av-bay.

So I cut it down...


And did a test fit with the coupler

I'm really glad that fit without modification because I had no idea how I was going to make that any smaller...

And the a test fit in the body tube


So now I know that everything fits nicely, I figured I might go about filling the spiral grooves on the body tube. But I don't have wood filler now so that will have to wait until tomorrow.

Today I picked up the I800 and I216 that this will fly on. The I800 will fly next weekend for the drag race, the I216 I will use to measure how far up the tube the retainer will go. The I216 will have to wait until I have access to a 15000' or greater waiver, I just don't want to accidentally punch any waivers.

Woke up bright and early today to get started working on this. Yesterday I acquired the following items to come very close to completion:
-5grain motor casing
-CTI I216 (will use at the next Red Glare for a 'dress rehearsal')
-CTI I800 (for use in the drag race)
-9' of 1/8" Kevlar shock cord
-6"x6" Nomex wadding
-24" parachute

So I got to work first by (carefully) removing the ejection charge from the I216, then installing the Aeropack CTI MD retainer adapter


Next I tied the shock cord to the bulkheads


Then a quick test fit


I didn't want to epoxy the retainer bulkhead in the tube until I had it cut to the correct length. So grabbed the parachute and Nomex to see how much room they took up. I concluded the parachute and Nomex took up 4" of and the shock cord took up 2". Of course it will fit a little tighter when it's inside the rocket


To the band saw!

The booster tube now measures at 24 5/8"

Final test fit before I epoxy ANYTHING


Now it's off to epoxy the retainer bulkhead in, then to remove the ejection charge from the I800 so I can set the retainer extension to the correct length.

So in my boredom of waiting for the epoxy to cure (I know it won't be until tomorrow) I did two things.

1. Removed the ejection charge from the I800 that I will fly on Saturday.


2. Using open rocket, I made a 3d render of this thing.

Got the fins today


Will attach tomorrow...

T34zac said:

Got the fins today
View attachment 182443

Will attach tomorrow...

Click to expand...

Is it just me, or are they not all the same? Or is the aspect ratio wrong (how?)?

CarVac said:

Is it just me, or are they not all the same? Or is the aspect ratio wrong (how?)?

Click to expand...

I think it's just the aspect ratio or some other weird optical illusion. I just went to look at them (as I left them the same after taking that pic) and they did look very wrong. I stacked them and they all matched up.

Today, (with the help of my father, since I don't know how to use a wood lathe) I made a nose cone for this rocket


Needs a layer of masking tape to make it a snug fit

Quarter of 3am local time... Just finished filling spiral grooves, will sand when I wake up...

Beveled the leading and trailing edges of my fins today

Now they are like knife edges

Things I still need to do to get this rocket flight ready:

-Make an Av-bay
-Finish sanding body tube
-Attach fins
-Prime for painting
-Paint
-Attach decal
-Clear coat

Days until launch: 3

Priming and painting may wait until after I800 drag race on Saturday.

You're cutting it it tight!

rocketgeek101 said:

You're cutting it it tight!

Click to expand...

Very much so. I figure I can get the fins on tonight after work, then I can put primer in tomorrow. While the primer dries I can start making an Av-bay (probably start that tonight after the fins). The primer dries very quickly so I can sand and put a second coat on soon after the first coat goes on. Then I can put the paint on. On Friday I can put the decal on, then clear coat it so it can be ready for Saturday. That's my schedule as if right now.

I'm very lucky to have a friend who is making the tower for me in Thursday.

Got the excess wood filler sanded off (only took forever). Also sanded the fins. Now they are ready for attachment


I decided that aligning the fins the same way I do A-C motor sized rockets (eyeballing it) was out of the question. So I decided to make an alignment jig. It can only do one fin at a time but it works. It will also need to be modified slightly so I can do the other two fins.


Now it's time to let that fin dry. Will do the next one in the morning. Will also make the av-bay in the morning. Doesn't look like it will be painted for this weekend

First fin is nice and snug. Also added a fillet on one side.

Will clean that excess epoxy after it dries.

Also started epoxying the second fin, made the necessary modifications to the jig.

Now the body tube rests on top of the jig instead of slipping inside it. I made that modification last night after posting, the first fin glued in just fine from it.

No pics this time. I just put the last fin in the jig to set. I also put fillets on the second fin. When I get back from work I expect those fins to be ready for sanding.

Av-bay has general design done. Just need to finish drilling the holes into the sled. The tracker has been friction fit into the nose cone. Next I need to drill holes into the bulkhead for the e-match terminals.

Tomorrow morning I will put the first coat of primer on. Then the second. Then paint. Hopefully the paint will be dry when I get back from work tomorrow so I can put the decal on, then immediately clear coat. Luckily it doesn't have a complex paint job

Days until launch: 2

I feel really bad for my friend right now who is working on my launch tower. He's been working on it for the last 5 hours now and I have no idea how much he has done. I really wish I could be helping him, but I'm stuck at work for now.

Just got back home. Added final fin fillets. Now curing under hear lamps


Now it actually looks like a rocket!


Now onto finishing the av-bay...

Primed the airframe. Will get onto sanding and reprinting in the morning.

Sanded then re-primed.

Also discovered this morning that I forgot to sand the fin fillets down. So I did that and then put the primer on. This will be ready for paint soon.

Base coat of paint is on. Still need to finish av-bay.

Payload tube also needs to get cut down, but I figured it was easier to paint it before waiting or the av-bay to be finished.

I have the structural pieces for the launch tower now. Just need hardware to assemble it.

For now it's off to work. Home early today.

Days until launch: 1

I've been thinking of how I'm going to secure the electronics sled inside the av-bay. Does stuffing tissues in with it sound like a bad idea?

bubble wrap?

Zebedee said:

bubble wrap?

Click to expand...

That would probably work better

It's still not done...

Looks cool. Can't wait for a flight report.