Rack Rocket Build

This is a quick build thread on the rack rockets I've been flying. This one is a 3 stage using Estes F15 motors.

The motors are 4.5" long and I use 5/8" masking tape for a thrust ring on the top motor so the rack needs to be 9-5/8" long.

The rails and supports are basswood, fins are balsa. Body tubes and nose cones are from Apogee.

Here are the pieces of wood with the parts marked.
The overall dimensions of the rails are 12" x 3/8" x 3/16", supports are 1-3/16" x 1" x 1/8", fins are from 1/8" balsa. The line across the basswood sheet is at 9-5/8, the rear of the body tube.
Cut out all the parts
Bevel the ends of the rails, sand the ends of the supports to 45 deg, and round the leading and trailing edges of the fins.
Using a spent 29mm motor, lightly friction fit the body tube to a second one that has alignment lines on it.

Now it's time for assembly, all done with yellow wood glue.
Glue on the rails
Then the supports
Once the glue is dry, remove the alignment tube
Finally, glue on the fins

I use an Estes style tri-fold shock cord mount and 1/4 elastic. The gold ribbon is the streamer, very visible at altitude. Add a couple short pieces of 1/4 launch lug (Aerotect FirstFire tube)
Cellophane tape the motors into a stack, add masking tape thrust ring to top motor, and friction fit into the body tube. Launch from 1/4 x 5' rod. [YOUTUBE]c1pqYgG-TOg[/YOUTUBE]
I consider these single use as the rack does get scorched This is the one in the video.

Excellent report, Tom! Do you have an estimate of the altitude?

Possibly coating the rails with sodium silicate solution might extend the re-usability, but maybe not. This is nice build thread and project. I'm also wondering what the altitude might have been.

Geez, that sounded like my big mouth in the background. That rocket flew really well. I can see why you're anxious to build another one.

The 4 stage E sims to about 3000 feet. I haven't simmed the F but I'd estimate 2500 or so. Parts cost is less than $7, motors cost about $25 with coupons, the rocket is expendable.

Is this like the one that you did at freedom launch?

F flight to a mere 2500? With the charring I'm thinking the upper body/NC/recovery system could be a modular unit. Of course, the cone and recovery components would be easily transplanted anyway, so I'm not sure modularity has much payback.

blackbrandt said:

Is this like the one that you did at freedom launch?

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That was a 4 stage 24mm with E12's.

rstaff3 said:

F flight to a mere 2500? With the charring I'm thinking the upper body/NC/recovery system could be a modular unit. Of course, the cone and recovery components would be easily transplanted anyway, so I'm not sure modularity has much payback.

Click to expand...

I can move the recovery and nose to another, lots of the time I don't recover them. The rocket is pretty draggy with the empty rack.

Pretty wild. Might have to build one of those for the new 29mm Estes.

Have not flown a rack rocket in years. think my last Achilles was lost at a Battle Park launch circa 1995-96 ( D20 and , iirc, 6 D12s )

will have to find a pic.

aerostadt said:

Possibly coating the rails with sodium silicate solution might extend the re-usability, but maybe not. This is nice build thread and project. I'm also wondering what the altitude might have been.

Click to expand...

Necro time !

"Paint" the rails with thinned JB WELD ( use Acetone ) . . . Just a thin coat to avoid adding too much weight !

Dave F.

THis plays great without JB Weld.

Old thread indeed, with comments from TRF’s legendary Gary Byrum, who recently has indeed slipped the surly bonds of earth.


I was wondering if carbon fiber rods or sticks might make a more durable “rack” that would survive more than one flight? Is carbon fiber THAT much more jet blast tolerant than balsa?

Also wondering if rack rockets tend to increasingly weathercock as they drop motors? Seems like with each motor dropped, the rocket velocity should increase (therefore fins become more effective and CP moves aft) while CG moves forward. Thus rocket becomes progressively more over-stable as it ascends.

Or does the increased velocity mitigate the weather cocking?

cwbullet said:

THis plays great without JB Weld.

Click to expand...

What does, Chuck?

From the pic, it looks pretty bad.

Dave F.

You said to paint the rails with JB weld. I said is plays or flys well without.

cwbullet said:

You said to paint the rails with JB weld. I said is plays or flys well without.

Click to expand...

Perhaps, but it's not durable, or even very safe, if it fails structurally on the 2nd or 3rd flight, with staged motors that are going to light.

Another possibility might be to use Kevlar to protect the surfaces.

To be honest, most only get 1-2 flights out of them. They lose them often.

Ken Good and other "Pre-HPR" flyers ( before it was "legal" ) have some interesting information about Rack Rockets, dating back to the 1960's, in some cases.

PDF below . . .

Dave F.

I only fly them once. Even when I recover them, there is no reason to try flying them again. If you want durability, use aluminum tubes for the rails. IMO, if the rocket costs less than the motor(s), the rocket is 'fire and forget'. Cost of the rocket includes any reloadable hardware so a rocket on reloads is NOT expendable.