The UAP Project

[NTP2]

R/C planes now have a computer to keep them stable and level wings if the human fark's up. Some more advanced ones can pretty much let a noob land one without much worry.

I know that is why I said so. But they also can be used for modals of real planes that need them.

 

[Joekeyo]

I think the kite people do more advanced aerodynamic than we do.
After all no kite has fins

Some have a tail.

 

[Rktman]

Got an opportunity to trim the ENIGMA with the motor tube and pylon taped on. Glide is actually better than expected considering the ENIGMA lacks airfoils of any kind. I anticipated a sink rate comparable to a Centuri Mach 10 or Squirrel works X-RV but it surprised me. Let’s just say it wasn’t the “controlled plummet” I was prepared for, but more of a “dignified descent’. But I know from long experience that it’s difficult to predict with certainty how a glider performs when hand-launched vs how it behaves after being released at near the speed of a pitched baseball. I’m looking forward to seeing what this one does when maidened.

 

[Rktman]

I was trying to find a way to dump weight by spitting the spent motor but would prefer to somehow bring it down on a streamer. I can’t just kick it rearward with the ejection charge because that streamer would almost surely snag on the aft “wing”.

The thought occurred to me to kick it forward along with the nosecone and streamer.



While it would reduce weight without the risk of an ejecting motor casing taking out the aft “wing”, some concerns would be:

• Would the sudden deceleration snap the pylon?
• With the motor, shock cord and streamer now directly in front of the glider, would I run into the same Red Baron problems faced by conventional RGs?

 

[lakeroadster]

I was trying to find a way to dump weight by spitting the spent motor but would prefer to somehow bring it down on a streamer. I can’t just kick it rearward with the ejection charge because that streamer would almost surely snag on the aft “wing”.

The thought occurred to me to kick it forward along with the nosecone and streamer.

View attachment 608854

While it would reduce weight without the risk of an ejecting motor casing taking out the aft “wing”, some concerns would be:

• Would the sudden deceleration snap the pylon?
• With the motor, shock cord and streamer now directly in front of the glider, would I run into the same Red Baron problems faced by conventional RGs?

What makes it eject?​

The ejection charge pops off the nose cone, and the nose cone pulls out the motor? Will that work?​

 

[NTP2]

• Would the sudden deceleration snap the pylon?
• With the motor, shock cord and streamer now directly in front of the glider, would I run into the same Red Baron problems faced by conventional RGs?

For 1 you could do the trick with the tissue paper and wood glue to make “fiberglass”.

 

[Rktman]

@BABAR had a really cool suggestion on how to do this in an elegantly uncomplicated way on TRF https://www.rocketryforum.com/threads/glider-front-motor-eject-feasible.181457/post-2472782

In summary, it involves a short section of 18mm tube that remains on the glider. A longer section forward of that contains the nose cone and streamer/chute. The motor is friction fit into the forward section of tube, and connects the two sections, held in place by a burn thread. When the ejection charge fires, it severs the burn thread, propels the forward tube section and motor forward while blowing the nose cone and streamer out. Very innovative – accomplishes the goal of removing weight in a reliable way because of its simplicity; nothing to go wrong unlike with a more complicated method. Thanks Tom!

Tom's sketch:

 

[Rktman]

What makes it eject?​

The ejection charge pops off the nose cone, and the nose cone pulls out the motor? Will that work?​

It should, especially if I use a heavier plastic nose cone that packs more mass than a balsa one. Could also add a little weight inside the nose cone to ensure things go as planned. BABAR devised a modified version of this (see previous post #37). There are only 2 outcomes, and it'll be interesting to see which way it goes.

 

[NTP2]

In summary, it involves a short section of 18mm tube that remains on the glider. A longer section forward of that contains the nose cone and streamer/chute. The motor is friction fit into the forward section of tube, and connects the two sections, held in place by a burn thread. When the ejection charge fires, it severs the burn thread, propels the forward tube section and motor forward while blowing the nose cone and streamer out. Very innovative – accomplishes the goal of removing weight in a reliable way because of its simplicity; nothing to go wrong unlike with a more complicated method.

That is an awesome idea. I like KISS and that is the KISS way to do things.

 

[lakeroadster]

It should, especially if I use a heavier plastic nose cone that packs more mass than a balsa one. Could also add a little weight inside the nose cone to ensure things go as planned. BABAR devised a modified version of this (see previous post #37). There are only 2 outcomes, and It'll be interesting to see which way it goes.

Seems like a perfect set-up for rear eject. Wrap a z-folded streamer around the motor and then it'll pop out the back at ejection?​

 

[Rktman]

Seems like a perfect set-up for rear eject. Wrap a z-folded streamer around the motor and then it'll pop out the back at ejection?​

My concern is to avoid ejecting anything rearward that could very likely take out the rear section of the glider. It would have to reliably bullseye the open center of the rear triangle every time. My other concern is that the rear section would also be likely to snag the streamer, causing a Red Baron situation.

 

[lakeroadster]

My concern is to avoid ejecting anything rearward that could very likely take out the rear section of the glider. It would have to reliably bullseye the open center of the rear triangle every time. My other concern is that the rear section would also be likely to snag the streamer, causing a Red Baron situation.

Is the motor / nose cone ass'y stable without the glider? If the answer is no, how about a tumble recovery?​

 

[Rktman]

Is the motor / nose cone ass'y stable without the glider? If the answer is no, how about a tumble recovery?​

I've had pop pods lose their streamers and they kind of float/tumble down harmlessly with no damage to the assembly. The streamer is just extra insurance, but mainly so I can find the pod later if it lands in tall grass/weeds/crops etc. I always use a bright red mylar streamer that not only self-unfurls itself quickly, the bright metallic material also reflects light like a beacon, making the assembly easier to find.

 

[BABAR]

It should, especially if I use a heavier plastic nose cone that packs more mass than a balsa one. Could also add a little weight inside the nose cone to ensure things go as planned. BABAR devised a modified version of this (see previous post #37). Thgere are only 2 outcomes, and It'll be interesting to see which way it goes.

The set up should eject the chute or streamer. The drag should the pull the now loose motor (only held on by rubber band, now burned) off the body of the glider.

There is potential for a Red Baron with this setup as well, which I hadn’t considered.

 

[tab28682]

R/C planes now have a computer to keep them stable and level wings if the human fark's up. Some more advanced ones can pretty much let a noob land one without much worry.

Some RC aircraft do have autopilots and flight control computers on board, but not all.

 

[Rktman]

Aft section of the motor pod was installed, and work commenced on the forward section per @BABAR’s idea.




Punched holes in the forward section for the motor anchor (cotton thread or elastic band) to be threaded through. Since a hole punch couldn’t reach 1.5” into the tube from the rear, I had to make a pilot hole and then use a twist drill to hand-auger out a 0.25” hole. Since it left a pretty ragged opening that needed strengthening, I was pretty chuffed that I finally found a use for these 0.25" grommets that I've had pack ratted away for decades. It ended up being the perfect solution.

 

[Rktman]

Used a modified Estes-style “teabag” shock cord anchor.

 

[Rktman]

Realized the motor anchor holes were way too large, and would vent far too much pressure and jeopardize ejection of the forward section and spent motor. Had to toss the tube and fabricate a new one. Luckily I found some 2.5mm (1/8”) diameter grommets in my stash to reinforce the holes with. Bonus points that they just happen to be a hue to compliment the usual orange color of my pop pods.

 

[Rktman]

To ensure ejection of the forward tube, I replaced the lightweight balsa cone with a heavier plastic one. Unfortunately it has a much longer shoulder, and I couldn’t reach deep enough into the tube to use the Estes-style shock cord anchor. I decided to just fabricate an anchor out of music wire and attach to the motor block.





...to be contined.

 

[Rktman]

Goofed. Put the launch lug right in the path of the motor anchor elastic. That will interfere with the launch rod and may cause binding.

Actually I goofed twice. If I had offset the rear of the motor pod backward maybe about a quarter inch (the ghosted-in portion at the rear with the orange arrow pointing to it) it would have served as the perfect anchor for a rubber band. Just need to loop the end below the tube end (shown in green).

As it is, I’ll have to remove the launch lug and relocate it, and install an anchor for the rubber band somewhere on the pylon (shown in magenta).

 

[lakeroadster]

Goofed. Put the launch lug right in the path of the motor anchor elastic. That will interfere with the launch rod and may cause binding.

Actually I goofed twice. If I had offset the rear of the motor pod backward maybe about a quarter inch (the ghosted-in portion at the rear with the orange arrow pointing to it) it would have served as the perfect anchor for a rubber band. Just need to loop the end below the tube end (shown in green).

As it is, I’ll have to remove the launch lug and relocate it, and install an anchor for the rubber band somewhere on the pylon (shown in magenta).

View attachment 610058

"If you have no failures, you're not innovative enough."

 

[Rktman]

That lug was on but good! Messy and took a fair amount of alcohol to soften the wood glue, and some stern encouragement with a hobby knife and chisel blade to finally pry the sucker off.




I was able to do some trimming and now it needs some nose weight to the tune of 5.52 grams. I’ve temporarily attached a self-adhesive lead balancing strip until I get another chance to get to the park for some trimming tosses.

With the launch lug relocated, I can now install the elastic or cotton thread anchors (a small segment of music wire capped with a plastic bead).

 

[Rktman]

Decided to shorten the forward portion of the motor tube by 0.25” so that I can secure the motor with a wrap of masking tape on the exterior. Not really a fan of friction fit, since the casing tends to swell with heat, making it difficult to remove.

 

[lakeroadster]

Decided to shorten the forward portion of the motor tube by 0.25” so that I can secure the motor with a wrap of masking tape on the exterior. Not really a fan of friction fit, since the casing tends to swell with heat, making it difficult to remove.

View attachment 610832

What are you using for paint? Interesting color.

 

[Rktman]

I need to do one more trimming session before I attempt an inaugural flight. Those two things may take a while to get to as I’m still recovering from recent major surgery, but considering this part of my rehab therapy. The weather has been anything but cooperative too; only double-digit wind gusts the past few weeks. And here I assumed winter made for calm wind conditions due to lower temps. Not so, apparently.

Will get to it as soon as I can though, so stay tuned.

 

[Rktman]

What are you using for paint? Interesting color.

Sharpie permanent markers. Not a showroom-quality finish but it gets the job done with virtually no weight penalty. Forward triangle is tissued for strength so the color is integral.

 

[Rktman]

Took a chance on my usual trimming area despite forecasted 15mph wind gusts. At 7:00 a.m. on a Fall morning, there is little if any wind stirring or joggers around when temps are in the low 50s.

Seems the glider’s front end still needs a bit more weight, I’m guessing maybe a gram or so, so I’m taking the opportunity to strengthen the pylon with tissue as @NTP2 suggested, using dope instead of wood glue. That should add the small amount of weight necessary while relieving concerns about the pylon shattering from the ejection charge.

 

[neil_w]

That is quite an interesting contraption. I hope you get some good flight video when the time comes.

 

[Rktman]

That is quite an interesting contraption. I hope you get some good flight video when the time comes.

Me too. Will keep the initial flight low (B4 or B6) so my GoPro can capture something visible on video.

 

[Rktman]

Since I had originally intended to connect the motor pod to all three front corners, I had previously made these pylon struts, so I decided I may as well use them. The front needs some extra weight anyway and these tip the scale at 2.46g together. They’ll add extra strength to the pod connection and additional insurance against the single pylon snapping from the inertia of the sudden backward force exerted from the forward-ejecting section.