Estes 1376 NASA Pegasus 300% upscale

Let the gathering of the parts commence.

Very cool. You cut those with hand tools?

I send my boy off to the high school with sheets of plywood and an Illustrator file. They have a laser cutter with a 12x24” bed.

Charles_McG said:

I send my boy off to the high school with sheets of plywood and an Illustrator file. They have a laser cutter with a 12x24” bed.

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Can he get carbon fiber cut? I have a project I'm working on....

Does CF laser cut well? Fiberglass is supposed to be pretty poor.

Charles_McG said:

Does CF laser cut well? Fiberglass is supposed to be pretty poor.

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only one way to find out? My guess is it will cut the same as FG. I was going to use my scroll saw, but I'm a klutz and would likely break things

Anyway- what motor mount are you putting in your Pegasus?

38mm.
The school has a CNC mill, but not a router.

That's good equipment for a highschool shop! My university has a CNC router and a few HAAS TL-3 and mills. Don't know the name of the CNC router but it cut a curved wavy computer modeled plywood board edge near perfectly for a sophomore design class that wanted an Art table for a local disability center. I've never used the router, only the variable speed lathes ,plasma cutter, and mills as engineer student. Anyways very cool project build. Hope you don't meet Flutter on this one, those are some big fins!

Charles_McG said:

Fiberglass is supposed to be pretty poor.

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That CNC mill would eat through this like butter.

Andrew_ASC said:

Hope you don't meet Flutter on this one, those are some big fins!

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I also. It’s big and light. I may never get around to trying to put a J in it.

The school has a plasma cutter. I wonder how it would do on CF.

My big boy, Alex, is only so-so at welding (MIG), but he is the o lay one in the class with oxyacetylene practice. He gets that at home, as we do lost wax casting in bronze and silver.

Charles_McG said:

I may never get around to trying to put a J in it.

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Because you're going right to a K, right?

djs said:

Because you're going right to a K, right?

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K Vmax, ‘cause anything worth doing is worth overdoing.

djs said:

Can he get carbon fiber cut? I have a project I'm working on....

Click to expand...

Charles_McG said:

Does CF laser cut well? Fiberglass is supposed to be pretty poor.

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No. The resin is atrocious, and dry it just chars. You need a fiber laser, waterjet, or CNC mill for CF plate.

A little progress

Outboard 24mm motor mounts on vanes.


Some dry fitting


Outboard pods


Parts for zipperless baffle


Downscale among the parts

I love this kit. I built several but unfortunately all have been scuttled.

More dry fitting


Making skins




My first vacuum bagging

Fins assembled.


Forward tip, thru the wall catch


Taping off for later gluing


I touched up the gaps in the skins with epoxy, while I had it out. That stiffened up the wing even more. Memo to me- make the skins better in the future and plan the core braces to underlay the skin seams. I guess I’ll be having some quality time with CWF to smooth it out v


Internal vane for wing root attachment

Question for viewers: I messed up one of the long tube-tube fillets. I got distracted and got around to pulling the masking tape late - it left the epoxy a lumpy mess. Any tips for improving it? Grind it down with a dremel? Pour more epoxy over it?

I wouldn’t pour more epoxy on it unless you needed it. Sand it down with sandpaper and/or dremel after it’s fully cured

Eyeballing the final size.



Working on filling and painting.

Are you going to use the Jewel-Osco bag as the parachute?

djs said:

Are you going to use the Jewel-Osco bag as the parachute?

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Drogue.

I may bring this thing down in two pieces. I think I want the aft/fin section to come down flat. I can rig an aft attachment point and harness chase, but haven't figured out how to sneak it back into the body tube at the break point. I built the coupler as both a zipperless and baffle design. It's not glued in yet, so I have some options. I've thought about cutting a channel out of it and gluing a piece back in, inside the couple diameter. To make a recessed channel for the external line to fit. Then having just a little notch in the upper tube. But I'm worried about hacking into that coupler.

I've also thought about making the channel in the upper tube - but don't want to weaken it, either.

Recent progress. Painting has slowed me down.

I put a wiring chase through the baffle-coupler.


Masking the wing root fillets. I taped off the region during painting, so I’ve got bare tube.


I foamed the upper part of the motor mount area, where the wing root tabs are. Just in case.


Stack check.

After much hemming and hawing, I retrofitted the coupler/baffle with a BT20 thru-tube.

I decided I wanted the ability to have a redundant separation charge, and I wanted it below the baffle. I looked at putting a big enough ‘thru-tube’ in the baffle to hold a Quark or Quantum (and battery) but decided there just wasn’t space as built. But the BT20 will hold a spent motor casing - not pressed into service as a charge well, with the ematch wires fed through the nozzle. I put a thrust ring on it and an 18mm motor rationed to hold it. I’ll have to wire it from above with a breakable connection.

Lovely build. I will be watching with interest.

Motor retention.

After much hemming and hawing, I went ahead and added about 180g of nose weight. Mortar in the nosecone topped with some 2 part foam, just to help keep it in place. I also added a 29mm motor tube and retainer to the nosecone to use as a little av-bay.

After updating my OR file with the actual weights - adding masses to get the correct overall empty mass and balance, I trust looking at the simmed -loaded- Cg more. So, what does it now say about the Cp and stability?

Well, I guess that depends on how good the Cp estimate is. But I have more to go on. I don't have an original scale Pegasus handy (and pleas for info have yielded nowt) - BUT - I do have the 55% downscale I built a while back. It flies fine. Well, it cones a bit when I put a Centuri mini B in it, but it still goes up! With an A10 in it, the Cg is about half of a main tube diameter aft of the front of the outboard tubes. The sim puts the Cg with a J285 in the 300% upscale fractionally -forward- of that location. Also, the wings are fractionally -aft- of the 55% build (I want it to stand straight upright without support, the original design would angle back, so I moved the wings a touch.)

So the big one balances like the mini, which flies fine.
I'm feeling a little better about this beast.

First flight. H160. Bong - TWA

Was an awesome flight to see in person! Perfect straight boost.

Dressed and ready for my L2 attempt.

My BT20/13mm mini version is sitting on the side tube.