The UAP Project

[Rktman]

The two additional struts now connect all three carbon fuselage tubes to the motor section, so the inertial force during launch will now be transferred evenly to the glider instead of just to the pylon and the single bottom carbon tube.






Will have to do another trimming session or two to finalize things. I can tell that a little more nose weight is still required, as the additional struts and CA fillets (still curing in these shots) don’t quite make up for the lead tape I had temporarily attached to the pylon.

 

[Rktman]

Enigma retrimmed and ready for its inaugural flight.

 

[Rktman]

I had the opportunity several weeks ago to send the Enigma up on an inaugural flight. Motor pod failed to eject and it came in ballistic. Glad I kept the flight low on a B4-2. The glider itself survived undamaged, likely because the streamer was ejected and slowed its fall. Surprisingly its flying surfaces were unaffected by the exhaust plume, other than receiving a light whitish coat of exhaust particles. The motor pod didn’t fare as well; it totally crumpled on impact so I’ll have to fabricate another.

Although I sanded the outside of the motor casing and coated it with graphite, the ejection still wasn’t enough to pull it free, so I’m thinking I’ll have to enlarge the aft motor tube’s diameter a tiny bit by slitting it and adding a patch over it.

Also, I suspect the openings for the retention thread/elastic allow too much of the ejection charge pressure to bleed off, preventing the forward pod section from being kicked free. Addressing both of these things should ensure the motor and forward pod section doesn’t bind and will get ejected on subsequent flights.

Inaugural Flight:

 

[Rktman]

Just to be sure, I fabricated another motor pod from spare parts and ran a ground test. This time I kept the thread/elastic retention hole to a smaller 3/32” diameter. The test definitely confirmed that forward ejection will work, sending the forward pod section a good 10' across the yard. The Enigma’s inaugural flight would’ve proved that had the pod not become jammed.

 

[Dotini]

I had the opportunity several weeks ago to send the Enigma up on an inaugural flight. Motor pod failed to eject and it came in ballistic. Glad I kept the flight low on a B4-2. The glider itself survived undamaged, likely because the streamer was ejected and slowed its fall. Surprisingly its flying surfaces were unaffected by the exhaust plume, other than receiving a light whitish coat of exhaust particles. The motor pod didn’t fare as well; it totally crumpled on impact so I’ll have to fabricate another.

Although I sanded the outside of the motor casing and coated it with graphite, the ejection still wasn’t enough to pull it free, so I’m thinking I’ll have to enlarge the aft motor tube’s diameter a tiny bit by slitting it and adding a patch over it.

Also, I suspect the openings for the retention thread/elastic allow too much of the ejection charge pressure to bleed off, preventing the forward pod section from being kicked free. Addressing both of these things should ensure the motor and forward pod section doesn’t bind and will get ejected on subsequent flights.

Inaugural Flight:






View attachment 617505

Very interesting rocket architecture. Keep going!

 

[Rktman]

HELP WITH IGNITION SOLUTION

Hi All, can any of you more experienced and clever guys advise on a practical ignition solution for this glider? Trying to squeeze fingers through the space between the "fuselage" rods to connect the leads is frustrating and near impossible. Preloading the motor with an igniter and soldering long leads to it and then taping it to the rod each time is a PITA, and I'd like to avoid using a fireworks fuse if possible. Thanks in advance for any ideas!

 

[Dotini]

HELP WITH IGNITION SOLUTION

Hi All, can any of you more experienced and clever guys advise on a practical ignition solution for this glider? Trying to squeeze fingers through the space between the "fuselage" rods to connect the leads is frustrating and near impossible. Preloading the motor with an igniter and soldering long leads to it and then taping it to the rod each time is a PITA, and I'd like to avoid using a fireworks fuse if possible. Thanks in advance for any ideas!

Here is a device that worked well for me on a similar project.

 

[Rktman]

Here is a device that worked well for me on a similar project.

View attachment 627698

The engineering on that is impressive. Any specs or diagrams you could send me? Lacking a 3D printer, maybe I could cobble together something close to it in balsa and other odd bits I have lying around.

 

[Dotini]

The engineering on that is impressive. Any specs or diagrams you could send me? Lacking a 3D printer, maybe I could cobble together something close to it in balsa and other odd bits I have lying around.

Here is the device itself. It consists of two steel washers epoxied together, with a wooden dowel epoxied into the periphery.

 

[Raythain]

Here is the device itself. It consists of two steel washers epoxied together, with a wooden dowel epoxied into the periphery.

View attachment 627728

Cool idea. You could also add a “cup” at the top for the motor, and then slide the whole glider down over it.

Epoxy a small section of appropriately sized tubing with a motor block at the bottom, so that it holds the motor vertical. Prep your motor. (igniter, clips, etc) and then slide the glider down to a good friction fit. Viola, no need to get your hands inside the airframe at all. Only requires a good friction fit on the motor.

I’ll try to mock something up later when I get the chance to illustrate.

 

[TheAviator]

HELP WITH IGNITION SOLUTION

Hi All, can any of you more experienced and clever guys advise on a practical ignition solution for this glider? Trying to squeeze fingers through the space between the "fuselage" rods to connect the leads is frustrating and near impossible. Preloading the motor with an igniter and soldering long leads to it and then taping it to the rod each time is a PITA, and I'd like to avoid using a fireworks fuse if possible. Thanks in advance for any ideas!

I don't have any photos, but the easy thing to do is to tape the igniter to a dowel rod, clip the leads to it, then set the glider down on the igniter. As long as the igniter is firmly in the nozzle, there's no need to install the plastic plug.

 

[Rktman]

Thought I'd show how little space there is to attach clips to the igniter because of the boxed "wing". My hands are too big so my wife had to do it, and even she had a really difficult time. Took about 5 minutes of frustration so I know she won't be doing it in the future (don't blame her).
To make things even more difficult, the end of the motor is recessed 1/4" into the motor tube because of the centering ring in the aft end to keep the motor from ejecting rearward.

 

[BABAR]

Very inelegant but perhaps effective solution.

Can’t remember exactly HOW I did it, but in late 70s I used some thing gauge non-non chrome wire, shaped into a tight V, which when connected to I think one of those big brick like batteries got pretty hot. When it didn’t light the motor casing on fire, it got hot enough to light the propellant.

I think some of the MicroMaxx rockets had something similar, the rocket basically “sat” on the igniter.

Me thinkin’ put the wire on the end of a dowel, the dowel is attached with an appropriate stand-off to the launch rod (or run it through a hole in the blast deflector plate.)

You already are gonna need to think a longer rod, since the rocket motor is already nearly a foot up the rod just to leave room for the long strut fin unit.

Anyway, gonna need a bit of juice, and probably will use up battery fast (? tempted to use rechargeable batteries but might burn them out, basically you are creating a short circuit.). Maybe some nichrome wire that is thin enough to heat up quickly, light the propellant, but not melt.

It’s basically the same as what others have mentioned, except maybe a but more durable.

Keep an extinguisher nearby in case the dowel catches fire.

 

[Cape Byron]

Just to be sure, I fabricated another motor pod from spare parts and ran a ground test. This time I kept the thread/elastic retention hole to a smaller 3/32” diameter. The test definitely confirmed that forward ejection will work, sending the forward pod section a good 10' across the yard. The Enigma’s inaugural flight would’ve proved

Those spare parts have Sky Condor written all over them.

Nice project. Looking forward to flight pics.

 

[Rktman]

Those spare parts have Sky Condor written all over them.

Nice project. Looking forward to flight pics.

Keen eye. Leftover pod from a Condor that caught a thermal and went permanently AWOL.

 

[Cape Byron]

Keen eye. Leftover pod from a Condor that caught a thermal and went permanently AWOL.

They will do that. Amazing glider for the money.