Helix: Tractor Motor - Helical Finned - Rear Eject

[techrat]

Well, the smoke trail indicates it has flown mostly straight without sky-writing all over the place so I'm going to say that I am suitably impressed!!

 

[lakeroadster]

Tractor Motor Installation

I used a Dremel to cut the opening, and then installed the BT-50H motor mounts. Once I get this glued into place I'll then drill a hole for the 3/8" launch lug on the rockets c/l.

The C-50's are just being used just to keep the BT-50H tube round.

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[jqavins]

Not for a tractor motor powered odd roc... it flies in the face of conventional rocketry protocol.

Popular myth, long ago debunked.

I have built a rocket, Thunk! , that used Gas Dynamic Stabilization. At launch the Cp was ahead of the Cg, and it flew just fine.

And a lovely rocket it is. GDS is a whole different subject. And there are other ways to achieve stability apart from typical fins. But the tractor effect, "It's stable because the tractor motors pull it up straight", is not one of them.

For this rocket, I expect the helix will be just about as good as a ring fin, so the CP will be fine. For BABAR's rocket that relies on the tractor effect, with fins way up the body, uh-uh.

 

[lakeroadster]

Launch Lug Positioning

I made a fixture using my wood lathe by turning a plug to fit into the end of the body tube. The plug had a hole for the shank of a 3/8" dia. Forstener bit. Then using the plug I drilled a 3/8" diameter hole for the launch lug. The upper part of the launch lug will slide into the 3/8" hole in the nose cone.

Now I need to order a 34" long BT-3 from BMS....

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[lakeroadster]

Helical Fin Supports

Attaching 3/16" dia. dowels for the helical fins.

 

[lakeroadster]

Helical Fin

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[neil_w]

Cool.

 

[lakeroadster]

Primer Day 01

Primered the rocket... knocking off the fuzzies and adding filler is up next.

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[lakeroadster]

CWF and Sanding

Sanded the helix fin, and added then applied some CWF to the nose cone and the upper motor mounts.

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[lakeroadster]

Engine Hook, Launch Lug and Kevlar Screw Eye

I want to be able to remove the motors without using tape... so I used engine hooks. The BT-104 sleeves hold the engine hooks in place.

The launch lug was cut and glued into place.

A small screw eye was attached to the hub of the nose cone to attach the kevlar too.

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[Daddyisabar]

Yes Mr. RSO, notice the positive motor retention. It is safe!

 

[BABAR]

Lookin’ good.

Will need a clip whip or so sort of extra wiring.

What is expectation if only one motor lights?

 

[Daddyisabar]

Lookin’ good.

Will need a clip whip or so sort of extra wiring.

What is expectation if only one motor lights?

Ignition failure is not an option.

 

[lakeroadster]

Will need a clip whip or so sort of extra wiring.

12" long e-matches with long clip whips...​

What is expectation if only one motor lights?

Simulation states still a successful flight.... but the motors aren't canted and offset.​

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I have yet to have a failure though, igniting D motors with e-matches. ​

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[lakeroadster]

Base Colors

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[lakeroadster]

Hand Painting The Spiral

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[Daddyisabar]

A giant barbershop pole or Santa's North Pole!

 

[lakeroadster]

Spray Painted Red On Body Tube

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[lakeroadster]

Photo Shoot

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[Daddyisabar]

GLAMOR SHOTS! Gotta get the model rocket all dolled up and down to the mall for a photo shoot, just like it was the 80's (Stranger Things times for the youngsters here on the Forum. ) The rocket might be from the upside down but hopefully it won't open a portal and we won't loose anyone by the pool. If the Demogorgon shows up we can launch it in his direction, the spinnyness sending him back to his layer. Yeah, the 80's were really like that. Now you just get the Glam app on your phone.

 

[BABAR]

That’s just begging for a pair of smoky black powder motors for a cool flight trail.

 

[lakeroadster]

That’s just begging for a pair of smoky black powder motors for a cool flight trail.

Two D12-3's

 

[lakeroadster]

Display Stand

This rocket needed a display stand since it won't stand upright. I made a center support out of redwood and attached it to a 1" thick piece of stair step. Both parts were turned on the wood lathe.

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[Daddyisabar]

"You put me high, upon a pedestal. So high that I could almost see eternity. "

Yes, after a long recovery process to collect all the bits of an oddroc crash, during the long ride home from the remote launch site, only the soothing sounds of Anne Murray's YOU NEEDED ME, will suffice on the car stereo.