World Air Force Supersonic Transport

[lakeroadster]

Here's a model based on some photos posted by @Ez2cDave on a post here.

This one is based on a BT-55. It has (1) 29mm motor and (3) 18mm motors. Initial flight will be on a 29mm, then the next flight will be on all (4) motors.

Main fins and the overhead fin will be 1/4" plywood.

Looks like a fun build.

 

[lakeroadster]

I checked stock materials and I have a length of BT-60... so I upscaled the design, but left the fins 1/4" plywood.

Only caveat here is I'll have to buy an 8 ft rail.

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[neil_w]

Isn't 1/4" plywood kind of massive (i.e. heavy) for a model of this size?

 

[Daddyisabar]

Asymmetrical drag and thrust! Widely spaced motors on an airplane rocket. Crazy. Maybe a little bit sick. Love it!

 

[lakeroadster]

Isn't 1/4" plywood kind of massive (i.e. heavy) for a model of this size?

Think of the force of three motors (24mm) acting down through the fins to the body tube. Yeah, I could probably get by with thinner, but I have 1/4" and it doesn't really hurt the overall performance.
<------ Plus... there's always this.

 

[Daddyisabar]

Think of the force of three motors (24mm) acting down through the fins to the body tube. Yeah, I could probably get by with thinner, but I have 1/4" and it doesn't really hurt the overall performance.
<------ Plus... there's always this.

Just bump the 18 or 24mm up to 29mm F15 4 all around. More weight in the nose. More High Power! Bulletproofing rules!

 

[lakeroadster]

Build Day One: Plywood

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[Daddyisabar]

Gone are the days of cheap, squishy Hobby Lobby balsa covered in 3M lable paper! MORE POWER ROCKS!

 

[lakeroadster]

Plywood Day 02 and Body Tube Cutting

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[Daddyisabar]

Looks like an episode from The New Yankee Workshop!

 

[lakeroadster]

Test Fit

 

[lakeroadster]

Gluing The Plywood, Day 03

Flipped the plywood over, used some ballast, and then applied wood glue to the bottom of the joints.

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[techrat]

That is some seriously thick plywood. I'm hoping half of it comes off in the sanding phase. Otherwise, we are talking 'H" motor to get this to fly.

 

[lakeroadster]

That is some seriously thick plywood. I'm hoping half of it comes off in the sanding phase. Otherwise, we are talking 'H" motor to get this to fly.

LOL... Hope in one hand, and then sand with the other...​

​

It fly's to about 600 ft on a single F50. And betters that with an F15 and (3) C6's. Look at the above simulations.​

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I do the math first... then build. ​

 

[jqavins]

I've been wondering what you plan to do with the V notches at the outsides of those joints.

The wood glue on the outsides will shrink while drying, so the V notches will become U notches.

What will you do then? Build up wood glue layers? Wood filler? TiteBond Q&T like @neil_w uses? Before the post above, I wondered if this might be one of those rare cases where original Gorilla glue (the expanding foam stuff) would be useful in a rocket build.

 

[lakeroadster]

I've been wondering what you plan to do with the V notches at the outsides of those joints.
View attachment 598253View attachment 598254
The wood glue on the outsides will shrink while drying, so the V notches will become U notches.
View attachment 598255
What will you do then? Build up wood glue layers? Wood filler? TiteBond Q&T like @neil_w uses? Before the post above, I wondered if this might be one of those rare cases where original Gorilla glue (the expanding foam stuff) would be useful in a rocket build.

Build up wood glue layers, then sand, then wood filler.​

I pretty much use Gorilla Wood Glue, and sometimes I'll add a wooden dowel as a filler for strength.​

Gluing The Plywood, Day 04

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[techrat]

I was betting on the dowels as this way you end with a nice rounded edge, which once painted should look smooth and clean.

 

[jqavins]

Honestly, had I thought about it ahead of time, I'd have expected a craftsman like to you miter those joints.

 

[Daddyisabar]

LOL... Hope in one hand, and then sand with the other...​

​

It fly's to about 600 ft on a single F50. And betters that with an F15 and (3) C6's. Look at the above simulations.​

​

I do the math first... then build. ​

Like the kids say these days: "Doing the math first is TIGHT!"

 

[lakeroadster]

Nose Cone Wood Lathe Turning

Well... knots happen. Nothing some CWF won't cover I guess. Open Rocket estimated 4.0 ounces.... and it came out 4.1 ounces. Pretty good, right?

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[lakeroadster]

Cockpit Turning and Installation

Turned the cockpit out of 1-1/4" dia. pine, cut the turned piece, scalloped out the inside and gluing it to the fuselage. Also, still gluing the 1/4" plywood and filled he knothole in the nose cone with cwf.

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[lakeroadster]

Test Fit

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[BABAR]

Build up wood glue layers, then sand, then wood filler.​

I pretty much use Gorilla Wood Glue, and sometimes I'll add a wooden dowel as a filler for strength.​

Gluing The Plywood, Day 04

View attachment 598258 View attachment 598259View attachment 598349​

That statue gets a lot of use!

 

[lakeroadster]

Sanding the Plywood

The glue is dry so I sanded the "up and over" sections glue joints with my 4" angle grinder. Then sanded the front edges of the fins by hand to have a slight edge radius.

Next up: Attaching The Fuselage​

 

[Daddyisabar]

Nose Cone Wood Lathe Turning

Well... knots happen. Nothing some CWF won't cover I guess. Open Rocket estimated 4.0 ounces.... and it came out 4.1 ounces. Pretty good, right?

View attachment 598301View attachment 598302​

Like in the cult classic movie DUNE... Very accurate estimate! Who's on that transport? Is that worm sign? Call in the carry all. They will work to the very last minute to get the maximum amount of spice. What a monster!

Bless the maker and his water. Bless the coming and going of him. May his passage cleanse the world.

Fly this one and the cluster staged Saturn V and you will be the Kwisatz Haderach!

There is a place where we Bene Gesserit safety flyers are terrified of. That garden where the clustered oddroc abominations grow. Look there and you will see Lakeroadster staring back at you! Ripping holes in space and time with staged clusters, widely spaced pod clusters and canted tractor motor horror shows. All the animals will seek safety in the box, the Bunker. Release the atomics!

 

[lakeroadster]

Attaching The Body

Using Gorilla Wood Glue and Then Titebond Quick and Thick

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[lakeroadster]

(3) Motor Pods and 29mm Mount

 

[lakeroadster]

Swing Test - Preliminary

Took the SST for a spin today... it's stable.

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[Daddyisabar]

Maybe some glue tabs for the pods? Bond only as strong as the surface layers of paper on the tubes that are attached to surface area of the glue.

Good thing I don't have to mindsim this one. All the asymmetric drag and variable thrust centerlines depending on various motor combinations would keep my puzzler sore.

It has passed the swing test. Lakeroadster no longer needs the weirding module!

 

[lakeroadster]

Maybe some glue tabs for the pods? Bond only as strong as the surface layers of paper on the tubes that are attached to surface area of the glue.

You know... I thought about that very thing.

But glue tabs simply add to the complexity. However you build them, they are still just glued to the cardboard? So, I eliminated them.