The UAP Project

[Rktman]

Got most of this build done but wasn’t able to start this build thread due to health issues. Recuperating right now so I’ll be posting as much as I can manage at any one sitting (all I have are photos at the moment). Hoping the build proves interesting…or at least entertaining.


From the concept pads at Farside Research comes this unlikely flying thing. It’s one of those mind sims that hovers on the border between “Not even close to being airworthy” and “It works but no one knows exactly why yet”. This is more an experiment to see which side of that dividing line it falls on.

Wasn’t sure if this box kite-like glider attempt should’ve gone into the Oddroc or Rocket Boosted Gliders forum sections. Gliding Oddroc or Oddroc Glider? While it may have gotten more traction in the Oddroc section, I decided that first and foremost it’s a glider, albeit an odd one.

I’m sure as a kid you built one of these straw and hoop gliders. You didn’t care about how or why it worked, just about how fun it was to watch something you made yourself out of a drinking straw, paper, and glue actually defy gravity as it soared across the room.



I still have no clear idea of the exact physics behind how an essentially “wingless” plane sans any airfoil can stay aloft.

Anyway, during an idle moment years ago, I regressed enough to build one of those straw/hoop gliders out of curiosity. Still couldn’t figure out how it worked, so my curiosity remained unquenched. So an even weirder thought hit me: would a different shape, like a triangle, still work? It did!




I resolved that one day I’d try to actually fabricate a full-scale triangular version that was rocket-launched. Well, those two straw gliders sat on a dusty shelf for about 7 years, but inspired again by the Ring Hawk glider I’d built 4 years ago following plans in an old Nov/Dec 2003 Sport Rocketry article, I decided to resurrect exploring an oddroc triangular “airfoil” glider-on-a-stick like the straw version—but upscaled, of course.

 

[Rktman]

After pondering way too long on names that incorporated “Tri-“ or “Delta”, I finally settled on something less obvious but more appropriate given how something so unorthodox and unlikely can glide: “Enigma”.

To be continued...

 

[lakeroadster]

Hope you get all healed up... looking forward to the build.

 

[Rktman]

Hope you get all healed up... looking forward to the build.

Thanks John, really appreciate that!

 

[Rktman]

I fabricated a downsized mock-up out of bamboo BBQ sticks and cardboard just to see what it would do when I tossed it. Unlike the kid’s version though, both “wings” are the same size and it uses 3 connecting rods instead of one to ensure strength and prevent the balsa “wings” from immediately shearing off from the acceleration.




I have no idea whether this unorthodox thing would actually glide decently, or if it would be more of a controlled plummet. I’d be elated if it’s the former, but would be okay if it behaved somewhere between the two extremes. As long as it didn’t go nose-down ballistic (which I don’t think it’ll do; the Ring Hawk glider works surprisingly well despite not having any decalage or airfoils. Post-apogee, it starts falling horizontally like the way a streamer-duration contest model falls. After a couple of seconds, it orients itself and starts “falling” towards its heavier front end, gliding horizontally as its ring-wings start to provide wind resistance).

Obviously it’ll be a tractor-motor setup so the rear “wing” will likely take some abuse from the exhaust plume. I’ll have to upscale it just enough to minimize that without making it too heavy.

I tried to model this in Open Rocket, but I’ve only just begun to play around with OR and it doesn’t look real flexible when what you’re modeling doesn’t resemble a “normal” rocket.

 

[NTP2]

I tried to model this in Open Rocket, but I’ve only just begun to play around with OR and it doesn’t look real flexible when what you’re modeling doesn’t resemble a “normal” rocket.

It’s flexible, you just have to push hard enough.

 

[lakeroadster]

I tried to model this in Open Rocket, but I’ve only just begun to play around with OR and it doesn’t look real flexible when what you’re modeling doesn’t resemble a “normal” rocket.

It can be done... here's a starter file...​

​

 

[Rktman]

It can be done... here's a starter file...​

View attachment 608170​

Cool, thanks!

 

[NTP2]

It can be done... here's a starter file...​

View attachment 608170​

After looking very carefully at the part manager I figured out the magic, you have a central tube that is invisible and a pod set around that with fins. Is that right?

 

[lakeroadster]

After looking very carefully at the part manager I figured out the magic, you have a central tube that is invisible and a pod set around that with fins. Is that right?

Pretty much.

The center tube isn't visible... because it's diameter is zero.

 

[NTP2]

Pretty much.

The center tube isn't visible... because it's diameter is zero.

Ok I see, you are very good with open rocket by the way.

 

[Rktman]

It can be done... here's a starter file...​

View attachment 608170​

Fast question: Is OR's CG and CP distance measured from the rear of the rocket or the forward end?

 

[NTP2]

Fast question: Is OR's CG and CP distance measured from the rear of the rocket or the forward end?

I think the front is the default, but you can change it.

 

[lakeroadster]

Fast question: Is OR's CG and CP distance measured from the rear of the rocket or the forward end?

Tip of the "nose cone".

 

[Rktman]

I think the front is the default, but you can change it.

Tip of the "nose cone".

Thanks guys!

 

[Dotini]

Obviously it’ll be a tractor-motor setup

Tractor motors have charmed me since Dr Goddard. I've built a couple, launching one extensively. Igniter connections were a nuisance for me, but it looks like you might have the opportunity to mount the motor outboard of the structure and make the connections much easier.

 

[NTP2]

Tractor motors have charmed me since Dr Goddard. I've built a couple, launching one extensively. Igniter connections were a nuisance for me, but it looks like you might have the opportunity to mount the motor outboard of the structure and make the connections much easier.

Scale Goddard rocket?

 

[lakeroadster]

Scale Goddard rocket?

https://www.rocketryforum.com/threa...kansas-by-fliskits.173883/page-3#post-2310588

 

[Rktman]

Tractor motors have charmed me since Dr Goddard. I've built a couple, launching one extensively. Igniter connections were a nuisance for me, but it looks like you might have the opportunity to mount the motor outboard of the structure and make the connections much easier.

Unfortunately too late, the glider is finished but I just didn't previously have the opportunity to post this thread.

 

[Rktman]

IIRC about a week later there was a low-wind day and I had the opportunity to do some tosses and the mock-up actually does glide, though not with the low sink rate of a more conventional glider with airfoils of course. Let’s just say that it doesn’t go uncontrolled ballistic, and has a trajectory much like the Centuri Mach 10. There might be hope for this oddroc after all.

 

[Rktman]

The three 1/16” thick balsa plates forming each “wing” need to butt up on their edges at a very tight 30° relative to the plane of the “wing’s” surface, so I threw together a sanding and assembly jig out of scrap balsa and recycled mock up parts. It provides the correct angle for the sanding block to bevel the balsa pieces at the correct angle.




I also cobbled together a couple of cardboard alignment jigs to make sure the carbon connecting rods (fuselage?) get glued in level and straight into the triangular “wings”.

 

[JoePfeiffer]

I once had a kite that had a very similar design.

 

[NTP2]

I once had a kite that had a very similar design.

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

 

[Rktman]

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

IMHO I'd say less advanced, all they have to do is keep the front of the kite facing the wind, done very simply by having a tail to keep it oriented.

 

[NTP2]

IMHO I'd say less advanced, all they have to do is keep the front of the kite facing the wind, done very simply by having a tail to keep it oriented.

Have you seen some of the big ones by the beach https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcT15TyQfDeJCKbvH4Ga2veJVHEJnFrFpI6Syg&usqp=CAU

 

[Rktman]

About a week later during a lull in the bad weather, I was able to dope and tissue the forward “wing”, and protect the surface of the aft “wing” with thin self-adhesive aluminum tape. The inside of the forward wing also got “aluminized” since it’ll get the hottest exposure from the motor’s exhaust.

 

[Rktman]

Have you seen some of the big ones by the beach https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcT15TyQfDeJCKbvH4Ga2veJVHEJnFrFpI6Syg&usqp=CAU

Nice designs, but easily controlled. https://www.britannica.com/topic/kite-aeronautics/Aerodynamics

Free-flight gliders require far more self-correcting stability and adherence to design/specific aerodynamic principles because there is nothing like a tether or human controller to make adjustments once it's up there. Like RC planes, you can make almost any shape fly (I've seen flat planks, Halloween witches, etc.) as long as you are controlling things from the ground.

 

[Rktman]

Once the “wing” sections were done, I was able to finish installing the carbon rods (fuselage).

I did some preliminary glide/trimming tests with clay, then weighed the amount of clay needed to see how much forward mass in the form of the motor tube/NC and pylon I could get away with, especially since the motor section will have to sit ahead of the forward “wing” to ensure launch stability.

 

[NTP2]

Free-flight gliders require far more self-correcting stability and adherence to design/specific aerodynamic principles because there is nothing like a tether or human controller to make adjustments once it's up there. Like RC planes, you can make almost any shape fly (I've seen flat planks, Halloween witches, etc.) as long as you are controlling things from the ground.

Ok I see, it’s the difference between active and passive control. A glider has to be stable by its own, but a kite or rc plane has active control by a computer or human to control it. Similar to how modern fighter aircraft have a computer to keep them stable.

 

[Art Upton]

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.