Mach One “Alien Interceptor” build

Awesome! I am still waiting on a motor mount so hopefully I can finish this rocket-I received a replacement about a week ago and it was too big and turned out to be a BT-55 coupler I think. Steve is a sending me a new one again after the new stock was cut (last week). This has given me time to figure out what to do with the payload section.

downhill_D said:

Awesome! I am still waiting on a motor mount so hopefully I can finish this rocket-I received a replacement about a week ago and it was too big and turned out to be a BT-55 coupler I think. Steve is a sending me a new one again after the new stock was cut (last week). This has given me time to figure out what to do with the payload section.

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My kit came in today and man, what a great kit!

Really well packaged and the parts are top notch.

Ordered the retainer today, hoping to get to building this weekend.

Nice! What retainer did you go with?

I have another kit arriving with the motor mount this week. I am really looking forward to seeing this Alien Interceptor fly! They are very nice kits-I am happy with the quality and the design! Solid kits.

downhill_D said:

Nice! What retainer did you go with?

I have another kit arriving with the motor mount this week. I am really looking forward to seeing this Alien Interceptor fly! They are very nice kits-I am happy with the quality and the design! Solid kits.

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Steve recommended the 29 L2 from Aeropack.

I tried buying from AP site but its was kinda wonkie so I went to apogee and got it there.

Going to start on the avionics bay first tomorrow.

Normzilla said:

Steve recommended the 29 L2 from Aeropack.

I tried buying from AP site but its was kinda wonkie so I went to apogee and got it there.

Going to start on the avionics bay first tomorrow.

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Aeropacks are nice. I havent used mine yet since I gave estes retainers a shot for my loc kits but these mach 1 kits will be getting the aeropacks. I like Apogee-they have a lot of stuff. The bay is where it really gets creative in my kit (besides painting)-so much room-these are big rockets for bt-60 tubing

Motor mount and another kit (antigravity) show up today! Pics by tomorrow! I made a quick jolly logic altimeter mount on the long bay this morning as well. Just some foam form fitted. Anyone know if the altimeter will still read correctly if surrounded by foam (except the face with the red button)?

which Jolly Logic are you using, I'm in the market for one

I have the Jolly Logic 2. Have not used it yet-cant wait to get real data though!

that's what I was gonna get

Ok. So after speaking with our Clubs vice president about the new
Mach 1 kit I re-sanded/roughed the fins using 100 grit. 400 was not deep enough. I received the motor mount for the Alien interceptor Friday -they have a new dyed version in black. Here are the first rings installed (i doubled them up since I had a second set) using JB weld and roughed with 100 grit in a crasshatch pattern as suggested by Steve Skinner from Mach 1. Once the motor mount is in I can install my fins. Next point - the fin slots were cut somewhat different lengths (all are long enough) to the aft end but the forward cuts all begin at the same
Location. My guess is the router was still being set for limits. I checked all fins and they are exact forward end of the fin slots. Once a motor mount is in and the fins are on I will fill all aft fin slot openings left over with the fillet material.

Now that the epoxy is dry I can add my kevlar shock cord retainer (kit comes with Kevlar cord). I use a simple knot with a slip knot once around the tube. No epoxy just titebond wood glue at the knots and pulled it tight. I do not glue it to the motor mount. I made sure the motor mount hole for the shock cord had no sharp edges. I will be adding a tubular nylon cord between the Kevlar and the forward payload (middle of the entire shock cord length) for shock cord relief.

I went to my next step of checking fit of my retainer and found out my aeropack And the Estes retainers are both not a large enough bore for the motor mount. A quick sanding of the estes retainer WILL work BUT the female side of the estes retainer will be outside the BT-60 diameter by enough to just avoid that retainer. It overlaps by too much. The aeropack however will work very well once the bore on mine is correct. I sanded mine carefully with a metal sanding/grinding drum on my dremel, carefully checking fit often, until the retainer fit over the fiberglass motor mount. The female end of this retainer sits nicely inside a BT -60 tube but I will check fit as I do want the motor mount aft a bit for engine removal.

I did consider leaving an access paper tube to run a small hole from the aft end of the motor mount to the forward centering ring for the purpose of a replacement kevlar shock cord. But I will leave that to a future larger diameter rocket...maybe my L2

That is looking great. And I like the New Black fiberglass. I also looked at the prospect of using an Estes retainer. And I've decided that I will sand off the plastic knubs so they don't stick out past the BT-60 body tube.

Also, make sure you use more then the 6' of cord Steve sent with the kit.

Thank you! I am taking my time but the fun begins now

I sanded the inside of each section I would be bonding using a piece of coupler with a strip of 100 grit sandpaper superglued around it (also taped to a motor casing to reach a hard to get to spot. This worked really well. Tilting it I was able to crosshatch all sections: fin slots, rail button holes and centering rings.

So I used jb weld for the forward fillet on the centering ring. This is new for me but I wanted a really solid bond of the body to the motor mount and didnt mind a bit of weight. I am probably gonna two part foam the fins inside so that will add a nice strength and heat resistance overall. I left the slots open, measured everything three times and used a 5ml syringe (no needle) with jb weld (about 3 mL) through the fin slots at a flattened angle and made “weld worms” in the three sections I was fusing. With the kevlar tucked inside the motor mount and taped together, twisted the mount up slowly toward the forward centering ring mark I made. (you can conveniently see right through)

I then babied it for about 2 hours till I was satisifed the motor mount wasn’t blocked and the kevlar did not get bonded. This was tricky. I then hung it upright with the modified retainer, and two aft centering rings “dry installed”. Once the forward ring is dry I will “tack” install the fins using 15 min epoxy. It got a little messy when the kevlar bundle fell forward out of the motor mount (short story) but the inside fillet is almost perfect.

Eric said:

That is looking great. And I like the New Black fiberglass. I also looked at the prospect of using an Estes retainer. And I've decided that I will sand off the plastic knubs so they don't stick out past the BT-60 body tube.

Also, make sure you use more then the 6' of cord Steve sent with the kit.

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Thanks! He sent me 12ft (2 6ft sections) with this rocket and I bought some tubular nylon bungee for in-between the two sections. I am hoping this will help absorb the shock quite a bit.

The aeropack retainer fits soooooo well.

Amazing fit. Great job. Will there be a gap with hardware loaded?

Thanks! It was not too tough but it is a close fit. Ordering the L2 would have been easier but I wanted to use what I had first. The aero pack fits just under the BT60 diameter. A gap? what do you mean?

A gap between the base of the retainer cap, and the bottom of the rocket tube. The motor hardware, when installed doesn't usually allow the aeropack to be tightened all the way down. Making it stick aft a little further.

Oh yes, but ever so slight.
Here is the retainer with and without my 29/240 casing with the cap screwed on. I have not been updating my sim program so I didnt bother to measure it. The retainer is only dry fit here. I have a rail button,fins and a centering ring or two to install yet. The difference with and without the motor is a few millimeters I think.

Oh no. That looks great. I dont see a gap at all. It's coming along very well, cant wait to start my next one.

And I believe you will be fine with one aft centering ring. Butted up against the fins. I cant think of a benefit of using two rings there.

Thanks, I may just stick with one, that is a good point. I was considering slotting one for mid-motor mount but that is a lot of work and its fiberglass so the fins and mount shouldn't move...if I prepare it right. Yes, I will always use aero pack retainers for this size kit now...it is a great minimum diameter match for this rocket-I cant believe how clean it fits-looking good now. I am also looking forward to my next kit-the antigravity he sent me for the delayed motor mount of this kit. It is their "prototype" build kit. Should be fun-this "anti gravity" kit is not dual deploy ready (no payload section) so it should go a bit faster on the build.

Did you use JB weld throughout the fins and motor mount on yours? I was thinking 30 min like I usually use and fillets of JB at this point. One JB welded CR seems like enough

downhill_D said:

Did you use JB weld throughout the fins and motor mount on yours? I was thinking 30 min like I usually use and fillets of JB at this point. One JB welded CR seems like enough

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I used BSI 30 minute for assembly, then Rocketpoxy for some big fillets. 15 of 30 minute will work fine. Just clean and scuff it well. Even a sharp razor cuts give it more to hold on to.

And JB Will work as well. For the fillets, it will just need some good masking tape dams to hold it in place if you are doing big fillets.

I like Rocketpoxy for my fillets. The pint size kit did 8 rockets worth of fillets for $33. I might just buy the 1 cup size kit $10, so it isn't sitting open as long.

Makes sense. Ill stick with my 30 min and probably use jb for the fillets. Has anyone flown a Mach 1 kit one yet? How were your flights?

downhill_D said:

Makes sense. Ill stick with my 30 min and probably use jb for the fillets. Has anyone flown a Mach 1 kit one yet? How were your flights?

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Just finished motor mount (rings, harness, aeropack), e-bay, push pin holes, sheer pin holes, vent ports. Fins going on tonight and rail guides tomorrow with fillets. Paint Thursday for flight Saturday on an F-67.

downhill_D said:

Makes sense. Ill stick with my 30 min and probably use jb for the fillets. Has anyone flown a Mach 1 kit one yet? How were your flights?

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Yup, flown the Portia about 8 times on 38mm H and I loads. No issues whatsoever. Great flights. Some are on youtube. Just search for PORTIA and LUNAR.

My 3" Black Hole EXT went to about 2900' on a J500. Beautiful flight. Carrying a heavy payload.

Eric said:

My 3" Black Hole EXT went to about 2900' on a J500. Beautiful flight. Carrying a heavy payload.

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Was this payload fermented?

swatkat said:

Was this payload fermented?

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There is no proof of that... But it sat on the pad for 45 minutes while they took a break to do the group photo. So it was a very warm can...

Eric said:

There is no proof of that... But it sat on the pad for 45 minutes while they took a break to do the group photo. So it was a very warm can...

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LOL. I heard it was a "Lite" payload.

That is great! I remember hearing about a contest recently on a podcast. Nice work.