Crayon

[rbeckey]

I am about half finished with a 4 x 38 inch crayon rocket. The tube is wrapped with irridescent mylar. I am using .093 Lexan for fins and, borrowing from another designer, I am making the rocket modular, so it can be disassembled for fin replacement. The forward centering ring is doubled up and one is attached to the motor tube, and one to the body tube, but not to each other. Three screws and friction hold the fin can/motor mount onto the body tube. Remove the screws, and the fin can/motor mount slides out the back. The motor mount/stuffer tube is a BT80 with mounts for a three E cluster and 29mm single built into interchangeable couplers. There is a kaplow type baffle built into the BT80, and 1/4 inch tubular kevlar wrapped around the motor mount for a zipper proof shock cord mount. The shock cord will be ten feet of 3/4 inch elastic. I have not acquired a chute yet. Something in the range of 40-48 inches, I think. I patched the coin slot by roughing up the inside of the NC and taping the outside, then filling the slot with epoxy and reinforcing with a nylon patch. I will end up painting the NC/tailcone after sanding the mold lines. I added 1 oz. of lead to the NC for stability. The fins will stay clear. Total invested in the rocket, minus the chute, is about $15. Pictures will follow when I can get my hands on the digital camera again.

 

[Micromeister]

Rbeckey:
Sounds pretty good!
for whats is worth, on my 5 D12 clustered 4" Crayon I used 4 - .063 clear lexan for the fins, in a clipped delta planform direct epoxy rivited to the base and tube. 12 flights no fin damage.
I like your interchangable section, pretty neat idea.
I fly my 4" clustered Crayon with a 36" hemi-chute, very nice soft landings. lift-off Pic in the clustering the classics thread in the lowpower section.

 

[rbeckey]

Here is a pic of the BT, tail with modular motor mount and NC. I will clean up the fins after I repaint the tailcone. They have tape residue on them. the forward centering ring is two pieces of 1/4 inch foam board epoxied together, the kevlar shock cord is epoxied to the tube.

 

[rbeckey]

This is the business end. It is set up for interchangeable motor mounts based in BT80 couplers. You can see the baffle up there, and the coupler that is the motor stop. The slop is what happens when good polyurethane glue goes bad. You can see the cap screws for the kaplow clips. The fins are .093 lexan, to the motor mount. I drilled 1/16th holes in the fin stubs near the motor mount and put thick epoxy rivets through the holes. I also used epanding foam to fill the fin can. The epoxy visible on the end around the motor mount will be sanded and painted later.

 

[rbeckey]

This is the three E cluster mount, built into a BT80 coupler. It will slide into the motor mount, to be stopped by the fixed coupler further up the tube. I am waiting on parts to build a 29mm mount in another coupler. It will have its own motor retention. The outboard clips will retain the whole coupler assembly. I coated the assembly with wood hardener, since it will be subject to removal. The motor retention clips were fashioned from windshield wiper parts.

 

[rbeckey]

This is the fixed thrust ring mounted in the BT. The forward centering ring butts against the bottom of this when the rocket is assembled. The fore end of the BT80 stuffer passes through the center of the thrust ring. As you can see the shock cord passes through also. The kevlar will actually only be an antizipper mount for 10' of 3/4" elastic. Small screws in the BT/shoulder of the tail cone will hold everything together, and I'll be able to take it apart to fix a popped fin or whatever.

 

[rbeckey]

4 inch Crayon ready to go! I managed to find a G80 and a couple G35 motors for it. It has a 28" Skyangle multi colored chute.

 

[rbeckey]

One more try on the picture.

 

[powderburner]

The Mother Of All Crayons

 

[iceage]

Originally posted by rbeckey
4 inch Crayon ready to go! I managed to find a G80 and a couple G35 motors for it. It has a 28" Skyangle multi colored chute.

WOOOOOHOOOOO!

Looks great.

Now you have to add digicam capabilities, dual deploy and a 12" GI JOE on a chute. :kill:

I have a pencil bank that screams on G80s. My wife loves those flights as I left the "deposit slot" open. When properly positioned on the pad, relative to the wind, it's actually a 'howler' on take off.

Patrick

 

[Micromeister]

She's a Beaut rbeckey!
I see why you went with the heavier clear fins through the wall, Landing on them will cause a good deal of flex. I'm thinkin 3 G's should put it up there a ways 5 D's put mine up a little over 800 feet. Have a nice hike 28" chute may bring her down a little hard, I started with a 30" true hemi chute, but went to a 36" hemi after the first landing bounced about 5 feet and damaged one of the outer motor retainers. Have flown her 7 times since with no damage at all. Here's the best lift-off shot I've managed.
Great Job, I love the sparkle paper should Flash real good in the sun

 

[rbeckey]

Actually, this is not a cluster, though I might have poorly worded an above post to make it seem that way. As small as my field is, one g is all I can reasonably do and expect to see the ship again.
The Skyangle chutes are theoretically very efficient for their size. I do have a 36 inch chute that I could use also. Here is a picture of the Skyangle.

 

[iceage]

Originally posted by rbeckey
The Skyangle chutes are theoretically very efficient for their size. I do have a 36 inch chute that I could use also. Here is a picture of the Skyangle.

What does she weigh, ready for flight? My pencil roc is a bit shorter than the crayon, but still comes in at 2lbs loaded. I use a 30" regular chute if there is little wind, and a 30" X-form at the VOA field. Always plenty of wind in Cincinnati!

Patrick

 

[rbeckey]

She weighs in at 31 ounces. Rocsim says 21 FPS coming in with the Skyangle. Too fast?

 

[iceage]

Originally posted by rbeckey
She weighs in at 31 ounces. Rocsim says 21 FPS coming in with the Skyangle. Too fast?

31oz? For a full size Ralphco crayon ? Are you starving that poor thing? I guess I didn't need the extra 3 tubes of two ton epoxy on mine!

My Ralphco pencil is 30oz fully loaded. Never lost a fin to landing too hard, even on the 30" X-form. Fins are 1/8" lite ply painted BRIIIIGHT pink! Gotta have an eraser, eh?

Unless your landing on hardpack Earth, or the possibility of roads, concrete ect. I would feel OK with the Skytangle. But that's just me. YMMV

Patrick

 

[Micromeister]

iceage:
Lift off weight is likely the difference. My Crayon, weighs in a 35.5 oz with 5 d12-5s and the 36" nylon hemi chute. I didn't add an excess amount of epoxy, I'm thinkin the basic crayon has a heavier "tube" more like log and looking at a recently purchased nose and base, I think the earlier plastic pieces were cast thicker back then. Maybe a 30" will do for Rbeckey's crayon.

Rbeckey:
Didn't I see multi motor tubes in the motor mount photo or am I mixing models again...CRS disease strikes again Sure would have been a fast and Hi flight on 3 G's, still one should get her up there, What did the sim estimate?

 

[rbeckey]

There are two motor mounts for this one. One is a three 24mm cluster, the other is a single 29mm. They are built into a BT80 coupler. I suppose, should the good news reported from the Senate pan out in its entirety, a 38mm could be constructed in the same fashion. I'd love to see this thing climb into the sky on a 2 grain Pro38. I don't think three 29mm mounts will fit in a BT80. Two would though.

 

[rbeckey]

Flight pics. Capture from an 8mm vid cam. This one shows small flame.

 

[rbeckey]

Movement.

 

[rbeckey]

Next

 

[rbeckey]

Almost gone. Very little rod whip with a 1/4 inch AT rod.

 

[rbeckey]

Coming home. Safely recovered. No damage.

 

[Micromeister]

That's the WAY! Great flight! Now lets see the 3 24mm flight, Then maybe built another mount for 5 D12's now yer talkin!

seriously congrats on a great project, should be a crowd pleaser for years to come!

 

[iceage]

Originally posted by rbeckey
Coming home. Safely recovered. No damage.

NICE!

So what size chute did you finally use?

I need to practice more clusters...

 

[rbeckey]

I used the 28 inch Skyangle. There is a picture of it a few posts back in this thread. The one I used looks exactly like that picture.
The Skyangle chutes spin as they descend, and it looks really cool with those bright colors.
It came in fast, but the ground was soft and it is well built. The field is small enough (and surrounded by trees) that I want it to come home quick, even from a modest altitude.
I am certain that the Skyangle chutes perform better than a size comparison would lead you to believe.

 

[CharlaineC]

where can I find plans for this one or others like it.