PEPP 1 Aeroshell

I spent too much time looking through my ROTW supplements and finally could not put it off any longer. I wanted to try and build a flying model of the Planetary Entry Parachute Program Aeroshell. Actually, I want to build both versions but started with the first.

I spent some time doodling in Autocad and came up with a scheme but that scheme required more than I am able to do. Next stop was Roachwerks and Gordon was able to give me advice and assurance. He then got a check and today I got a box of parts.

First out of the box was the nose cone. It is sized to fit a 3" tube.

Next out of the box was a bag of what at first glance would seem to be a dozen nose cones. Actually, they are a dozen hemispherical ends fitted for a BT50. They are going to be the tops of my Falcon engines.

Gordon recommended PML tubing and, true to his word, a piece of 3" tube was next out of the box.

The really hard part was the after bulkhead. It had to be drilled for 12 separate BT20 tubes at a 35 degree angle. I then had to come up with a way to miter all those BT20s together. Gordon solved the problem and simplified it a bit. He balsa to the top of the plywood bulkhead and gace it a shoulder to receive the BT. He then drilled through both. Now the only miters will be the angles on the motor nozzels and I think I have that taken care of.

Just for grins, I stuck it all together. This is a project that is going to take some time and I have other priorities right now but I had to do some playing tonight.

My plan was to generate the shroud of the aeroshell in Autocad, transfer it to Illustrator and add the artwork then print it out. That is where I've hit a snag. I've posted a plea for help here: https://www.rocketryforum.com/showthread.php?t=49651

I'm excited about this one and will use it as a testbed for the PEPP 2!:surprised:

Awesome model JAL! I've like the PEPP since I saw the first photos from White Sands. The closest I've come is an el-cheapo version from an Art Applewhite 10" (12"?) saucer without the top section cut out.

JAL3 said:

Gordon recommended PML tubing and, true to his word, a piece of 3" tube was next out of the box.

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Well, it wasn't what I recommended...it's what I had.

rstaff3 said:

Awesome model JAL! I've like the PEPP since I saw the first photos from White Sands. The closest I've come is an el-cheapo version from an Art Applewhite 10" (12"?) saucer without the top section cut out.

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This is one I want to show Art. He has'nt made the last few club launches here in SA. I want to have this one working and dependable when the Kerrville launches start back up. That's after deer season is over.

sandman said:

Well, it wasn't what I recommended...it's what I had.

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Mea culpa...but you don't have it any more. I do!

I'm also very appreciative of that.

Thanks again.

Decided to celebrate the 21st of November (it only comes around once per year, you know) by starting work on my PEPP aeroshell. The first thing I wanted to do was get a handle on the motor motors. After checking the CAD drawings I had made, I decided to cut 12 pieces of BT20 to a length of 4 inches. Cutting tubes has never been one of my greatest skills so I decided to try something new. I purchases a small hose clamp that is finger tightened. I then proceded to mark out 4" increments on my tubing and set the clamp in place as a cutting guide.

After a while, I had a dozen segments of BT20 tube, all about four inches long. I learned that the clamp works most easily if it is not tightened too much. I tighened it just enough so that my thumb could hold it in place as the X-acto did its damage. When I could not gut any more because of the screw, I rotated the clamp, used the blade of the knife to get it flush with the cut and started to cut again.

With the tubes cut, I worked them into the centering ring that Gordon of Roachwerks had cut and immediately noticed a problem. The upper ends of the tubes were interfering with each other. 4 inches was too long.

I only wanted 1.75 inches exposed from the bottom of the centering ring as measured from the longer side (due to the angle). I removed all but one of the tubes and used a tape measure to decide that the tubes would probably fit if cut down to 3.25 inches. I proceeded to mark all of the 4" tubes at 1.75 and 3.25 inches and recut them.

I took the shortened motor tubes and inserted them all into the centering ring up to the 1.75" mark. There was a slight bit of crimping at the forward end of some of the tubes but they seemed workable to me.

Nice idea of using a hose clamp, I will have to try it. For cutting tube I like to use an exacto razor saw as I find it much easier to control. This is going to be cool one to fly. A scale saucer, who would have thunk it!

John,
You are a Building Machine!
This is a great project, along with all the other projects you have been knocking out lately.

Keep'em coming.

(We still have those printouts for the 19' N1 laying about)

terryg said:

Nice idea of using a hose clamp, I will have to try it. For cutting tube I like to use an exacto razor saw as I find it much easier to control. This is going to be cool one to fly. A scale saucer, who would have thunk it!

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I got the idea from EMRR. I tried using a razor saw once, about a year ago. The result was not...good. Maybe I should give it another try with the clamp as a guide. I still have a dozen BT50s to cut.

Pem Tech said:

John,
You are a Building Machine!
This is a great project, along with all the other projects you have been knocking out lately.

Keep'em coming.

(We still have those printouts for the 19' N1 laying about)

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I still have fantasies about that N1. I still want it clustered right!

Looking good, man! May be one of the best build reviews I've seen recently. BTW, Art has seen mine. I'm sure he'll love your's but all that tube cutting is a hand-kitter's nightmare. Could but them I guess.

PS Enter the scale contest if not too late! Built or not!

rstaff3 said:

Looking good, man! May be one of the best build reviews I've seen recently. BTW, Art has seen mine. I'm sure he'll love your's but all that tube cutting is a hand-kitter's nightmare. Could but them I guess.

PS Enter the scale contest if not too late! Built or not!

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I really want to surprise Art with this one. Right now things are looking dicey. The huge format plotter I was depending on for my shroud is on the blink and hte techies are just scratching their heads. I can't justify replacing it since I'm not in practice anymore.

For what it's worth ... I had tried a PEPP Aeroshell once ,,,

There was , UM ,, Undersired , but predictible results... From something that was supposed to be dropped in the upper atmosphere and then fired toward the earth...


12 canted G40 motors , dipped ematches ... Because of the small nozzle throats two opposing ignitors caught in the motors and the Aeroshell " SPUN " on the wires..

Paul





View attachment aero15 (3).JPG

Rocketman94952 said:

For what it's worth ... I had tried a PEPP Aeroshell once ,,,

There was , UM ,, Undersired , but predictible results... From something that was supposed to be dropped in the upper atmosphere and then fired toward the earth...


12 canted G40 motors , dipped ematches ... Because of the small nozzle throats two opposing ignitors caught in the motors and the Aeroshell " SPUN " on the wires..

Paul

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I'm hoping that BP will be easier to ignite and that the spit plugs will be less prone to that sorth of thing than igniter wires.

The operative word in the preceeding statement was "hoping". This will definitely be a heads up flight.

Cool pics, by the way.

I still have the rocket, I was going to reconfigure it to a center launch lug that go's through the shell , instead of three 8" long ones ( that didn't go through the rocket ) as I had tried before, AND switch to 12 F20's
I believe that their shorter length will look better ! I will also be using hand dipped 30ga ignitors that don't have the Ematch " chip " on the end of them that can get caught in the nozzle !

-P

ok this one has me scratching my head as i thought their was a limit to the number of allowed moters in a cluster. 12 seams to me to be way to much but i dont know. I like the concept though.

Just depends on how much propellant and impulse you have as to where you cross the line into needing a cert to fly it.

I believe the HBoMR has a statement about the number of stages where 3 is about the limit of diminishing returns. Don't think there was anything in there about clusters.

kj

CharlaineC said:

ok this one has me scratching my head as i thought their was a limit to the number of allowed moters in a cluster. 12 seams to me to be way to much but i dont know. I like the concept though.

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I figure with a dozen 18mm Cs, I'm still only in the midpower range and won't even have to brush the dust off of the L1.

Its and experiment. If I knew what was going to happen, I wouldn't need to do it, although I probably would anyway.

zog43editor said:

Just depends on how much propellant and impulse you have as to where you cross the line into needing a cert to fly it.

kj

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That's the way I see it. Of course I've been known to have strange visions.

One of the ideas I was really messing with when I decided to do this was to build an MMX cluster that would qualify as a level one...

I still have some sketches. It got very ugly very quickly...

JAL3 said:

That's the way I see it. Of course I've been known to have strange visions.

One of the ideas I was really messing with when I decided to do this was to build an MMX cluster that would qualify as a level one...

I still have some sketches. It got very ugly very quickly...

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John:
While I haven't flown a dozen C6's, I have done 12- B6's on several occasions using my tried and true relay ignition system and home made, pre and post installation tested pyrogen tipped ignitors.
If your diligent during preperation and attachment, 8-to 12 motor BP clusters are pretty darn reliable. your Aeroshell should fly just fine. I've often thought about building one myself on a slightly smaller scale
12 C's would however put you over the 125g of propellant LMR class

Shortly after the introductions of the MMX-II motors, I looked at building a cardstock 9.25"dia. x 80" model to house a 1033 micro cluster (320Ns) just for fun.
I'd all but convinced myself it's be a good "bridging demo" model, but the thing just got to be far tooooooooooooo much of a waste of perfectly good micro motors.. not to mention motor money. I tried to rationalize the use (or misuse depending on how you look at it), tho it'd still have been about the same total bucks most of the HPR folks spend on a single flight. While I'm pretty much open to doing just about anything....I just couldn't being myself to build it. It simply made no more sense then buidling and flying APCP....BP forever:lol:

Micromeister said:

John:
While I haven't flown a dozen C6's, I have done 12- B6's on several occasions using my tried and true relay ignition system and home made, pre and post installation tested pyrogen tipped ignitors.
If your diligent during preperation and attachment, 8-to 12 motor BP clusters are pretty darn reliable. your Aeroshell should fly just fine. I've often thought about building one myself on a slightly smaller scale
12 C's would however put you over the 125g of propellant LMR class

Shortly after the introductions of the MMX-II motors, I looked at building a cardstock 9.25"dia. x 80" model to house a 1033 micro cluster (320Ns) just for fun.
I'd all but convinced myself it's be a good "bridging demo" model, but the thing just got to be far tooooooooooooo much of a waste of perfectly good micro motors.. not to mention motor money. I tried to rationalize the use (or misuse depending on how you look at it), tho it'd still have been about the same total bucks most of the HPR folks spend on a single flight. While I'm pretty much open to doing just about anything....I just couldn't being myself to build it. It simply made no more sense then buidling and flying APCP....BP forever:lol:

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I'm going to be doing some research and experimentation before committing to an actual launch. I want it to work right without having to go through too many major rebuild itterations.

My thoughts right now are running towards the Quest Super Cs for the extended burn time. I want to order some and see how they work.

If you have any plans for your conception of the super-duper MMX cluster, I'd sure love to see them. I think it would be an interesting project and it seems that MMX motors are no longer going to be as scarce as I'd feared they might become.

In terms of ignition, I was thinking in terms of a bunch of spider tubes from a BP flash chamber...Its not like anyone particularly likes my eyebrows anyway.

I know I have a sick mind but right after posting my last, I had visions of making my L3 cert flight with a MMX cluster. If only the delay were longer...