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McDonnell Douglas "Delta Clipper" Semi-Scale Build

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jmmome

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The DC-X was an experimental reusable single stage to orbit vehicle from the 1990's. My semi-scale model is 18" square at the base, and will stand about 4 1/2 feet tall. 3" Blue Tube for central structure tube, and will use Chute Release for main chute deploy. Smaller Blue Tube on the left is the 1010 rail guide tube.

Binder Design CNC'd the three plywood internal sections. Threaded rods connecting the internal sections. Plenty of RocketPoxy and external centering rings holding the central tube to the plywood internal sections. The outside will be fiberglassed. 4" dia. nosecone to be custom turned. Initially planning to use a J800 motor- final weight of the rocket TBD.

Photos of progress to date, and what it will hopefully look similar to.

Spring flight!

Mike Momenee
TRA #12430 L3
IMG_3710.jpgDCX-Main.jpg
 
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Nick@JET

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Whoa this should be interesting ! Very cool Mike!
 

neond7

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I actually did some work on the Delta Clipper when I worked for McDonnell Douglas. 😎 Nothing too major, we had some of their engineers on site and I supported their computers (I'm an IT guy). It was enough that I had a CCN charge code to bill my hours to. Too bad it fell over and went boom......
 

rstaff3

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There was a nice scale one at an ancient LDRS/BALLS. The guy built a fiberglass shell that slipped over the frame. IIRC it launched on a K something or another. Needed more nose weight :(
 

jmmome

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Thanks for the tip about the nose weight. I'm having Gord at Roachwerks turn a custom hardwood cone for me. I'll add some additional weight to it.

I'd love to simulate this build on Rocksim, but I don't have the faintest idea how. Open to any and all guidance.

Mike Momenee
TRA# 12430 L3
 

jmmome

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Ready for a fiberglass skin and a custom wood nosecone.

IMG_3711.jpg

Mike Momenee
TRA#12430 L3
 
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markkoelsch

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Mike, I think you best option to simming it would be to sim it as a cone.
 

rstaff3

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The theoretical cp for a pyramid should be 1/3 up from the base. I have heard of several longer pyramids that did not fare so well. I might opt for a bit of extra margin.
 

markkoelsch

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The theoretical cp for a pyramid should be 1/3 up from the base. I have heard of several longer pyramids that did not fare so well. I might opt for a bit of extra margin.
Agreed. You need to put some fins on this, nose weight, and make sure you have good amount of static margin.

Lightweight fins.
 

rstaff3

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Agreed. You need to put some fins on this, nose weight, and make sure you have good amount of static margin.

Lightweight fins.
Yup, several of the long HPR pyramids I've seen ended up needing fins. But not all of them! This video show's Neil McGilvray's Cat's in the Cradle vs Deb Kolom's...wait for it...DC-X.

[video=youtube;hzKjG3xHWZI]https://www.youtube.com/watch?v=hzKjG3xHWZI[/video]
 

jmmome

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Thanks for the comments, guys. I did sim it as a cone, based on your recommendation. It flies, at least inside the computer.

Mike Momenee
TRA#12430 L3
 

rstaff3

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Neil's pyramid in the video weighs in at about 175 about 75 of which is nose weight. :eek:
 

markkoelsch

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Thanks for the comments, guys. I did sim it as a cone, based on your recommendation. It flies, at least inside the computer.

Mike Momenee
TRA#12430 L3
I was also thinking that the best way to do this would be to base the base diameter of the cone the same area as the dcx. Best bet of getting it close.
 

tab28682

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That video does prove that a properly balanced DC-X does not need fins to be stable, even if quite heavy.

It could have used a more reliable recovery system, though.
 

rstaff3

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They always recover. Nobody has left one up there yet. :D But, yeah. I guess that was actually a DC-y ala the old Quest kit.
 

jmmome

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I'm adding clear polycarbonate fins and several pounds of nose weight (so far, the rocket only weighs 10 pounds without the to-be-made fiberglass skin). Hoping to bring it in around 20 pounds, but that might be optimistic. It may only fly to 900 feet with a K motor, but it should be fun to watch! It will definitely be a "far pad" launch, so as not to endanger the crowd.

The build is closely based on the scale of the actual DC-X, so hopefully, with the addition of fins and significant nose weight, it will live to fly another day.

Mike Momenee
TRA #12430 L3
 

jmmome

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I double-checked my 78" Top Flight Crossfire main chute with Chute Release attached, and it fits nicely in the 3" Blue Tube, and the package is only about 12" long. With piston ejection, it should leave the tube nicely.

Mike Momenee
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rstaff3

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I'm adding clear polycarbonate fins and several pounds of nose weight (so far, the rocket only weighs 10 pounds without the to-be-made fiberglass skin). Hoping to bring it in around 20 pounds, but that might be optimistic. It may only fly to 900 feet with a K motor, but it should be fun to watch! It will definitely be a "far pad" launch, so as not to endanger the crowd.

The build is closely based on the scale of the actual DC-X, so hopefully, with the addition of fins and significant nose weight, it will live to fly another day.

Mike Momenee
TRA #12430 L3
My faith in the stability of such things drops with motor impulse, so I might opt for some smallish clear fins too.
 

jmmome

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IMG_3740.jpg

Added significant nose-end weight, and four clear polycarbonate fins mechanically attached. Started fiberglassing the nose end of the rocket. Expect the rocket to weight in at about 30 pounds without motor.

So far, the CG looks very good. I'll check it again when I receive the 75mm 2560 casing and reload, and add more nose weight if necessary.

Next portion of the project is to create an avionics hatch/bay for the altimeter and back-up timer.

Mike Momenee
TRA# 12430 L3
 

jmmome

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IMG_3741.jpg

Added access hatch for altimeter bay. Added hardwood-turned nosecone (thanks, Gord). Will use BT-60 tube for altimeter bay, glued to back of access hatch with one sampling port of appropriate size drilled through both. Airtight bulkheads on both ends of tube. Rotary switches will be mounted on access hatch for power-up of altimeter and back-up timer.

Mike Momenee
TRA# 12430 L3
 

burkefj

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That looks good. I'm thinking this is a perfect design for a lightweight foam structure.....
 

EeebeeE

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Quest Rockets sold a kit that flew on C6-3s. I really liked mine. Had 2 oz. of nose weight and no fins. Great flier, but it needs higher impulse motors. Have you thought about how you are going to put it on the launch pad?
 

rstaff3

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Quest Rockets sold a kit that flew on C6-3s. I really liked mine. Had 2 oz. of nose weight and no fins. Great flier, but it needs higher impulse motors. Have you thought about how you are going to put it on the launch pad?
It flies even better on composite D's :D Looks like there is an internal lug in the photo.
 

jmmome

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I did think of the launch rail question. Running the entire length of the 48" long 3" dia. Blue Tube body tube, and epoxied to it, is a 48" long 38mm Blue Tube coupler tube. which coincidentally fits perfectly over a 1010 rail. So I simply slide the rail through the tube for my initial guidance. I sanded down the nose cone portion that would have come in contact with the launch rail. We'll see how it all actually works on launch day in the spring.

IMG_3742.jpg

Mike Momemee
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Quest Rockets sold a kit that flew on C6-3s. I really liked mine. Had 2 oz. of nose weight and no fins. Great flier, but it needs higher impulse motors. Have you thought about how you are going to put it on the launch pad?
I remember that kit. I had one in the early 2000's. Flew it multiple times with no issues, it met its demise when it had a recovery failure on about its 10th launch.
 

rstaff3

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I remember that kit. I had one in the early 2000's. Flew it multiple times with no issues, it met its demise when it had a recovery failure on about its 10th launch.
IIRC the nose is completely full of clay. On mine, the cord attachment point broke so I beefed it up. I lose a landing leg everytime. They are now pretty crooked :)
 
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