Hypersonic glider...

Mugs914 · Feb 15, 2021

I got the build jones a couple of weeks ago so I built this little glider. The design has been rattling around in my skull for a few years, I just never got around to it until now.

It is based on hypersonic, scramjet powered airplane proposals that have been floating around for decades. Some folks think that something like it was actually built and flown in the dark world.

Fun build, and I was actually able to get it trimmed out and gliding pretty well. Flies quite fast, as you would imagine, but probably won't be catching too many thermals!

It wasn't built with the idea of boosting it with a rocket, just as a cool looking chuck/catapult glider. After achieving such a nice glide I think I'm going to have to come up with a booster of some sort!

aerostadt · Feb 15, 2021

Fun looking glider! The bottom scram-jet and body contour is true to form/concept.

Rktman · Feb 15, 2021

Sweet!

Mugs914 · Feb 15, 2021

Thanks guys! Yeah Aero, I figure a real one would want more of a multi-angle forebody for more efficient compression, but I needed some extra room for a bit of nose weight inside!

That. And, well, its a balsa wood glider. It would become vapor long before such things became important...

Mugs914 · Feb 15, 2021

Well, the booster idea I came up with was inspired by this, and many other proposals that involved delta shaped vehicles with large fuel and oxidizer tanks wrapped around them, that were being bandied about in the sixties.

This is what I've come up with so far:

BT-20 tubes, nosecones from Semroc. There will be a 13mm mount on each side, angled outboard slightly, and a streamer on each side for recovery. I figure that two parachutes would inevitably tangle and become streamers anyway, and two tangled streamers are still streamers. Besides, the booster will be quite light.

I'm planning on some dummy engines on the rear behind the glider and a few fiddly details just to make it look like a real thing. The launch lug will go somewhere in the middle and will be "disguised" as part of the details.

For paint I'm thinking a typical 1960s Air Force/NASA research vehicle scheme; black X-15ish job on the glider, silver tanks with white and orange hi-vis patterns, various metallics for the dummy engines. Of course the first flights might be nekkid until the concept is proven.

Should be fun!

Updates to follow!

tab28682 · Feb 16, 2021

Very cool! Always great to see modelers thinking outside the box like this.

Adam3836 · Feb 16, 2021

Mugs914 said:
Well, the booster idea I came up with was inspired by this, and many other proposals that involved delta shaped vehicles with large fuel and oxidizer tanks wrapped around them, that were being bandied about in the sixties.

View attachment 450817

This is what I've come up with so far:
View attachment 450822
View attachment 450823
View attachment 450824
View attachment 450825
View attachment 450826

BT-20 tubes, nosecones from Semroc. There will be a 13mm mount on each side, angled outboard slightly, and a streamer on each side for recovery. I figure that two parachutes would inevitably tangle and become streamers anyway, and two tangled streamers are still streamers. Besides, the booster will be quite light.

I'm planning on some dummy engines on the rear behind the glider and a few fiddly details just to make it look like a real thing. The launch lug will go somewhere in the middle and will be "disguised" as part of the details.

For paint I'm thinking a typical 1960s Air Force/NASA research vehicle scheme; black X-15ish job on the glider, silver tanks with white and orange hi-vis patterns, various metallics for the dummy engines. Of course the first flights might be nekkid until the concept is proven.

Should be fun!

Updates to follow!

This is really interesting
Very creative
Nice work

Sooner Boomer · Feb 16, 2021

That looks great! Hope you can get a vid or at least pictures of launch!

Rktman · Feb 16, 2021

Can't wait to see how this turns out!

Ez2cDave · Feb 16, 2021

Now, THAT is VERY COOL !

I'm looking forward to seeing more and the flight video's !

Dave F.

BABAR · Feb 16, 2021

You had me at the glider, before you put the tubes on it. Glider looks like a cross between the Valkyrie and the B2.

I am a bit iffy on the tubes, kinda cool, kinda clunky.

if I read you right, you want to put motors on the ends of THOSE tubes? I see problems.

1. Canted motors seem cool (I haven’t done any), but I seem to remember they need to be aimed at the CG. IF I understand correctly, well designed Canted motor rockets like Deuces Wild and Tres will still likely be stable even if all motors of cluster don’t light. The degree of “outboardedness” of your motors at the end of your tubes I think is gonna be borderline even if both light simultaneously and are perfectly balanced (and I understand ejection charges are +/- 10%, I have always assumed thrust variability was similar. Anyone with knowledge to contrary please feel free to correct me.). If one doesn’t light, you are looking at a cartwheel.

2. The glider should easily work as a parasite on a rocket body that has it’s own fins. not so sure how it will fair on boost as a solo glider. Might be ideal as something along the lines of the MPC Lunar Patrol, but you’d need to build two of them.

Ez2cDave · Feb 16, 2021

BABAR said:
If I read you right, you want to put motors on the ends of THOSE tubes? I see problems.

My main concern would be Pitch stability . . . Of course, if both motors don't ignite simultaneously, a whole new set of problems arises !

Dave F.

Mugs914 · Feb 16, 2021

Gotta agree with a lot of what you said!

BABAR said:
I am a bit iffy on the tubes, kinda cool, kinda clunky.

That's true, and I think it is an aspect that I like. Looking at the pic up top of the FDL-5, you've got this incredibly sleek thing with these bulky tanks wrapped around it that make it look like a Zodiac inflatable boat. There were many proposals back then that had this kind of clunky tank arrangement. It was an interesting time in aerospace and I wanted to reflect that era.

BABAR said:
if I read you right, you want to put motors on the ends of THOSE tubes? I see problems.

Yeah, I guess I've invited a couple of rowdy guests to the party, but if it was a sure bet it wouldn't be quite as interesting. It looked like it would be a fun problem to try and solve.

That said, some thought and actual math has gone into this thing. Regarding the outboard motors, ideally, the thrust line should go straight through the CG, but in this case the thrust line of the two motors will intersect just a bit ahead of the CG, but much farther aft of where it would be if the motor mounts were not canted in the "tanks". In this case the thrust offset is roughly equal to a motor set about 1" off center and parallel to the centerline of a 10" long rocket. Any differential in motor thrust would cause a deviation, but it should be slight. In the case of a single motor launch the flight profile should not be so much of a cartwheel as a nice, beautiful, sweeping arc (that leads to the scene of the crash).

BABAR said:
2. The glider should easily work as a parasite on a rocket body that has it’s own fins. not so sure how it will fair on boost as a solo glider. Might be ideal as something along the lines of the MPC Lunar Patrol, but you’d need to build two of them.

My initial thoughts were along those lines, but I had already done one and decided to try something different.

This one was built about twenty years ago and is a lifting body type glider inspired by the FDL-5 like in the pic above. The side boosters have 13mm mounts that DO thrust through the CG! The glider trim is tricky, but when it's right it has a pretty impressive glide performance. I'm thinking of a similar paint scheme for the new glider.

Mugs914 · Feb 16, 2021

Ez2cDave said:
My main concern would be Pitch stability . . . Of course, if both motors don't ignite simultaneously, a whole new set of problems arises !

Dave F.

Pitch stability under boost actually looks pretty good, but yaw stability might need some help. I'm thinking I might put a sub-fin on the booster unit for a bit of insurance!

BTW- Both nosecones will be carrying a bit of ballast to get the cg at the right place for boost. How much will be determined later as the build progresses.

Mugs914 · Feb 16, 2021

Got a bit more done on the booster rig today.

Started with the actual motor mounts. I cut two 2" lengths of BT-5 and got out the centering rings.

I found that I didn't have any motor blocks, so I sawed two out of an old motor case.

Because they were going to be canted in the "tank" tubes, I decided to glue the centering rings into the tubes first. The booster was balanced on a C6-7 motor until the glue set.

Then it was easy to put a big blob of glue on the inside wall of the tank, slide the motor tube in through the ring and stick the motor tube in the glue on the wall. This worked well and after babysitting the motor tubes for a little while to make sure the alignment was correct, I ran a bead of glue around the centering ring. Repeat for both sides and we have motor mounts!

Here's how the end up relative to the glider.

Oh, and while prowling through my collection of parts I came across these dummy engines. A bit smaller than I had in mind, but it gives some idea of the look I'm after for the rear dummy motors.

Mugs914 · Feb 16, 2021

Once the motor mounts were done I took care of the shock cords. 2.5 feet of kevlar thread fixed with mini tea bags.

Once that was done I turned my attention to the attachments for the glider. The little slot on the rear of the glider came in handy!

This piece is made up of two layers of 1/64 ply, laminated and sanded to fit into the slot, and balsa blocks.

Two 1/8" shims were fitted to the sides of the glider and wedged into the booster tubes. This holds everything securely while the glider attachments are built up and fitted to the booster rig. When the shims are removed the glider will be suspended by the attachments and have room to separate from the booster.

The little L-shaped bracket was inserted in the slot on the glider and sanded to fit to the rear crossmember of the booster rig.

Here's what it looks like without the glider.

This rear glider bracket will be the base for the dummy engines and other little detail bits. I have an idea for the front glider mounting hook that may be a bit ambitious, but if it works it'll look great!

Thanks for looking!

Mike

Ez2cDave · Feb 16, 2021

Mike,

Are the Wings at a zero Angle of Attack, relative to the thrust line ?

Dave F.

Mugs914 · Feb 17, 2021

Ez2cDave said:
Mike,

Are the Wings at a zero Angle of Attack, relative to the thrust line ?

Dave F.

Funny you should mentioned that Dave!

No angle set in glue yet, but I'm thinking I'll set the glider ever so slightly nose up relative to the thrust line to counter the downforce created by the drooped wing tips (the droop and angle of the wingtips causes them to act like elevators). Even set at zero I don't think there would be enough to cause a PLOD (power loop of death), but might be a bit straighter with a tad of positive incidence.

Jeff Lassahn · Feb 17, 2021

On a design like this, do you build in some intentional roll, to turn potential loops of death into corkscrews of nervousness?

Ez2cDave · Feb 18, 2021

Jeff Lassahn said:
On a design like this, do you build in some intentional roll, to turn potential loops of death into corkscrews of nervousness?

I am always prepared for a "heads-up" flight . . . LOL !

Dave F.

Mugs914 · Feb 19, 2021

Jeff Lassahn said:
On a design like this, do you build in some intentional roll, to turn potential loops of death into corkscrews of nervousness?

It's a good thought... To be honest I was so concerned with the pitch and yaw under boost that it never occurred to build in a bit of roll. I would prefer a straight boost if possible, but I suppose if it gets a bit sporty under power I could add some angle to the sub-fin on the booster to induce a bit of roll.

I really appreciate the input, Thanks!

mbeels · Feb 19, 2021

Very cool! I love it! This looks like it'll be a blast to fly

Mugs914 · Feb 19, 2021

Thanks Marten! I figure whether its a success or failure it'll be an exciting flight!

Mugs914 · Feb 19, 2021

I mentioned above that I had a somewhat ambitious idea for the front glider attachment hook. Well, it got a a bit out of hand...

I wanted t do something that looked 'scale' rather than just a balsa stick glued between the tubes with a hook on it. The shuttle (the real one) was secured to the external tank assembly with tubular struts and this was my first idea; struts built up from carbon rods or something like that.

After a bit of thought I realized that it would be a bit too fragile for actual flight use, so came up with the idea of a fabricated yoke type attachment. If it were real it would be some sort of aluminum structure, but in this case 1/64" ply would suffice!

First step was to make the actual hook and the matching slot in the glider. The hook was built up from 2 layers 1/64" ply along with a base plate. The slot plate for the glider is also 1/64" ply.
.

The next step was to get the glider set on the booster sled at the proper angle. As was discussed with Dave above, I did decide to set it slightly nose-up relative to the booster. This was done with a 5/64" shim between the bottom of the wing and the tanks.

With everything in position everything was measured and the first piece of the rear yoke was cut from ply. This was glued to the ply sheet and then cut out to make a two layer laminate. It was slotted to fit with the hook assembly.

At this point things turned sharply left...

I looked at the parts and thought, "Y'know, a REAL one would probably be an aluminum fabrication of some kind with reinforcement pieces, lightening holes and stuff like that..." (I attribute the following excess to being stuck at home all week due to the freeze)

Lightening holes were drilled, reinforcement plates cut out and glued and edges capped... Much fitting and sanding went on and voila; one massively over engineered small (tiny) rocket part!

I made some reinforcement plates for the tanks out of cardstock and then the hook assembly was placed in the glider, the yoke was fitted to the tanks and everything was glued in place. With the rear hook yoke glued in, the glider was removed and the process was repeated for the front yoke.