Mach One “Alien Interceptor” build

Normzilla said:

Hey does anyone have an .ork file for this kit?

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You can download it here: https://www.mach1rocketry.com/store/p57/Alien_Interceptor_BT60_1.63"_(38mmXL).html
Scroll to bottom. It's on the bottom right.

Designer Fly said:

You can download it here: https://www.mach1rocketry.com/store/p57/Alien_Interceptor_BT60_1.63"_(38mmXL).html
Scroll to bottom. It's on the bottom right.

Click to expand...

Thanks!

I had posted the file you all sent me some time back earlier to this thread.

Great kit BTW

Okay!
-final gloss coat
-drilled a small hole mid payload section for the altimeter
-drilled a small hole behind the forward rail button for the JL Chute release.
-Tied up the chutes (18” drogue and 30” main) to the shock cord spaced the keep the nose/payload away from the body/fin can
-tested function with an air pressure test
-tested funtion of the JLCR
i think this is almost ready to fly!

Next is weights and measures for total weight and CG.

I am torn as to whether I should bond the coupler to the payload or use shear pins or maybe friction fit. Any ideas? The wooden payload I built is ample room but it’s MORE room...what do you do?

I’ll try and get some sunlight pictures tomorrow if I can

On my 38mm FG kits I just add a piece of masking tape and friction fit the "top" of the A/V bay to the upper body tube. No pins needed. 54mm so far has worked well the same way on 7 flights. Shear pins though for anything bigger.

OK. Does anyone know in fps or mph what speed a rocket can safely fall? I've settled on ~10mph but have no idea of a baseline for this. I am starting to think an 18" and 30" isnt quite enough for the weight of this rocket-even if it is fiberglass. It weighs 1 lb. 11.2 oz. with everything including a 29/240 case (no propellant loaded). For low speed according to simulation it would require a 60"? Am I missing something?

Okay here is the file I made from scratch for this rocket- including measuring all parts before building. If you see discrepancies please let me know, especially if you are a rocksim user. In advance I have been using rocksim for about 2 months and have a few motors plugged in based on what I have available to me. I am trying to learn as much as possible and I do understand that other sim programs give different results.

downhill_D said:

OK. Does anyone know in fps or mph what speed a rocket can safely fall? I've settled on ~10mph but have no idea of a baseline for this. I am starting to think an 18" and 30" isnt quite enough for the weight of this rocket-even if it is fiberglass. It weighs 1 lb. 11.2 oz. with everything including a 29/240 case (no propellant loaded). For low speed according to simulation it would require a 60"? Am I missing something?

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I try to keep mine below 20 FPS on hard dirt, 24fps on soft grass.

30 inches should be fine. I have rockets in the 28 Oz. range that are on 30's or 28's.

swatkat said:

30 inches should be fine. I have rockets in the 28 Oz. range that are on 30's or 28's.

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Good to know! Thank you!

I ended up adding plastic rivets to the payload body tube so my access to the coupler payload would remain available below my wooden electronics bay and not permanently bonded. Friction fitting was too finicky due to tolerances being so good on the fiberglass. I added all-thread and nuts to hold the lid to the coupler on and this nylon nut in turn "positive" locks my wooden electronics bay when loading the payload. Pretty cool. I'll add photos this weekend!

This has been a fun build and now that all the numbers are crunched in simulations this bird goes up tomorrow. I will probably start with a G77 for the first flight. It gave the best flight within "sight"

I will definitely get some videos of my "Alien Interceptor" and will post them here.

Video of this bird will have to wait till next months launch. I ran out of time for a practice flight and did my level 1 test (passed!!) with a different rocket right before it went dark. Just. In. Time. I did fly the antigravity yesterday and it shot straight and fast on an F39-5T. I need to sim antigravity-I made an educated guess and got lucky with that motor choice.

The G77-7 is all built up (LMS) and waiting to fly the Alien Interceptor next month. The G80 is also ready (new blue thunder). I will make sure to fly it on an "H" or "I" as well.

The G77-7R was a perfect flight in all senses. I’ll post up the data once I get home. It will fly on an H180 and 220 next month.

The data for the Alien Interceptor maiden flight is below. The altimeter used was a Jolly Logic Altimeter 2 and a Jolly Logic Chute Release which fits depending on chute size and material of chute. Thinner the better for larger chutes. I used an Apogee brand 30" nylon ripstop chute that is soft like silk and wraps to a very small size. very nice chute. the 18" chute was a rocket man chute.

The data:

Motor: Aerotech G77-7R LMS

Altitude:1647
Top Speed: 273
Burn Time:1.34
Peak Acceleration: 12.9 G's
Avg Acceleration: 9.3
Coast to Apogee: 7.8 seconds
Ejection Altitude: 1562
Descent Speed: 19 (using an 18" drogue w/ a 30" main at 500)-tight fit for the JLCR-take your time wrapping the chute!
Flight duration: 62 seconds

Enjoy!

Nice Downhill, Congrats on your first FG build. I am looking forward to watching your progress. Thanks for sharing.

So the latest flight was with a H210 Redline with a 14 second delay. Flew twice with the same motor and only once with the ALT2 altimeter. I used 1 small drone LiPO (Venom brand Fly 300) for the eggtimer on both flights in 95+ heat and had plenty of battery afterwards. The second flight showed interesting results:

I had predicted with rocksim, about 3780 ft on an H210 redline 14 second delay.

the ALT 2 data:
3534 ft
467 mph
.97 burn time
24.1 peak acceleration
22 avg acceleration
13.4 to apogeee
-13.3 apogee to eject
bad data ejection altitude
bad data descent speed
210.9 Flight duration

The eggtimer reported a max of ~6500 ft from our starting 2100 ft altitude at the launch pad. Anyway I have an I205 that I think the eggtimer can track now so I am shooting for the 1 mile plus club next flight on this bird. It sims at 6200 now with Cd adjustment after about 8 flights of G77's and H210's.

I need more data and a better altimeter mount for the ALT2 (it just hangs on kevlar) but I would say the flight was well over 4000 ft. I also purchased a data logger to solder on the eggtimer for downloadable data in google earth.

I will post video of the H210 flight later in the weekend. Very fast flights with what I think was a tiny bit of "coning" in flight around 300ft or so (maybe?) but hard to make out in video. Winds were low-under 8 mph.

I205 is a sweet, hard hitting motor. Please post results.

Seeing this quite late but what 30 minute epoxy do you use to build a fiberglass kit? I attempted a BT60 AGM Piercer kit, washed it, scored and sanded all glue surfaces nicely, used BSI 30 minute for the fins, came back a day or so later to do fillets and the fins snapped off like it was nothing. Had to trash the kit as I couldn’t get the epoxy off.

You really, really don't want to start a glue war. Do a quick search and find what works for you. Odds are it won't be "hobby" stuff.

I will only say that conventional methods of "scoring" the fiberglass had similar results for me on my first fin-I was just tacking and realized it wasn't enough. I used an exacto razor blade (about 5 actually) to HEAVILY cut the edges of the slots 1/4" around several hundred times in two directions at an angle. The pictures I posted should help-it will look like you will get a splinter if you touch it when they are ready for epoxy. Also the 30 minutes epoxy will "run" better when warm, hence it will get into the fibers quicker before setting up. I used 30 minute bsi internal and external bonds, jb weld on the forward motor mounts only, (an extra fiberglass forward motor mount ring was used), and rocketpoxy fillets. under normal circumstances the only time I have had the epoxy fail like that is when it didnt penetrate the fiberglass or I didnt measure it correctly. (I weigh my epoxy now). I hope that helps.

For the Wallace...yes-this baby is gonna rip fast! it will do about 600 with the I205 and you better believe I will video that flight for you all and myself!

I have the motor and have prepped it for the safety notice change aero tech made for this particular motor (CA on the thrust ring-it was 3d printed ). It will be a nerve racking moment but a beautiful flight.

I would also mention this is a really bitchin' kit and wish I had two. This one of the best designs (in my opinion) from Mach 1 and it goes FAST. For the price it is an excellent deal...once you build it. If you want a dual deploy this kit has tons of space-I use a chute release and it is a very tight fit but it works. I get it to fit with a 30" lightweight chute with a rockeman 18".

Also for my current landing distances the tracker has not lost signal with the black metallic paint on the rocket...maybe it wasn't metal in the paint or it isn't heavy enough to block signal.

Cool, sounds like problem solved...

So modular...I can now hold a lipo battery for my tracker and an ALT2 in my alien. The Japanese razorsaw to the rescue...again and again....and some wood glue:

Very neat work! In an age of custom print sleds, it's nice to see something like this occasionally

Nytrunner said:

Very neat work! In an age of custom print sleds, it's nice to see something like this occasionally

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Thanks! Its faster for now, I enjoy crafting what I want to see. Almost all thanks goes to some advice to buy a Japanese backsaw (razorsaw). I want to get a small cnc but prefer to do things manually-finding a manual benchtop mill is next!

For the record I still have the I-205 with this rockets name on it...soon

This is a great thread and thanks for doing it Downhill. If you don't mind I will add some notes because you made some very good points but they are quite old now.

When building these kinds of kits DO NOT skip the safety stuff. I have worked with resins professionally for a very long time and I NOW have an issue with some. The cheap resins can put me in the ER because my airways close down. Even the high end resin I use will bother my hands if I do not wear Nitrile gloves. Latex gloves will not stop the nasty chemicals in epoxy resins. I do not always wear my mask if i am sanding outside or where I have amazing ventilation (in my shop with the garage door open) but otherwise wear a bask of some kind. You do not want to be sneezing blood, been there. There are no really old auto body guys left.....

On the build, you did some very nice work !! Your attention to detail is impressive.

CA also works very well on fiberglass components. It works very well to spot weld stuff in place or to knock down fuzz. For fuzz, let it wick in and then sand smooth.

ThreeJsDad said:

This is a great thread and thanks for doing it Downhill. If you don't mind I will add some notes because you made some very good points but they are quite old now.

When building these kinds of kits DO NOT skip the safety stuff. I have worked with resins professionally for a very long time and I NOW have an issue with some. The cheap resins can put me in the ER because my airways close down. Even the high end resin I use will bother my hands if I do not wear Nitrile gloves. Latex gloves will not stop the nasty chemicals in epoxy resins. I do not always wear my mask if i am sanding outside or where I have amazing ventilation (in my shop with the garage door open) but otherwise wear a bask of some kind. You do not want to be sneezing blood, been there. There are no really old auto body guys left.....

On the build, you did some very nice work !! Your attention to detail is impressive.

CA also works very well on fiberglass components. It works very well to spot weld stuff in place or to knock down fuzz. For fuzz, let it wick in and then sand smooth.

Click to expand...

Thanks! I was patient with this build-having a good workspace was key to getting a build thread to be useful. I agree on the safety-we are all working with some super dangerous stuff-be safe about it so you can keep having fun with it!

I love this kit-it is loaded with great features for dd and way more payload room than most payload carrying rockets!

CA
I actually have a fuzzy altimeter porthole I will do this-makes sense-works for cardboard!

Nice build thread, and good luck with the I205 flight! It is really going to scoot. I like this design as well, I also did mine with 1010 buttons. Last week it flew on an I175 to 6198'.

yes the 1010 buttons are awesome on this rocket-the announcer once said, “yes, there really is a rocket on that pad”...so sleek-fast bird!