USR “F with Multiple D Pods” build thread

[J Blatz]

I’m a big fan of USR kits and have had this one in the ridiculously large kit pile for a long time. It’s along the lines of so many USR kits with BT70H tubing, balsa NC, and fins repurposed from the Banshee kit (best MPR kit ever IMO).

This thing has a 29mm core MMT and as the name spells out 4 24mm pods. I intend to fly it with mostly Estes combos, using core motor ejection. The kit instructions have you build it so the pods vent into the main body of the rocket thus allowing use of the outboard pods delay/ejection but I’m not doing that given the poor results of such construction in the past.

Parts is parts pic.

 

[J Blatz]

First thing I did was sand a slight bevel in the leading and trailing edges of the fins and sand the sides smooth. Then I applied a coat of some water soluble wood sealer to the fins. I masked off some of the fin root to keep the sealer off that part for better bonding.

While that was drying I made a fin/pod marking guide cuz the one it came with was not very good. Marked the tube using a doorframe to draw lines.

Next day I sanded the sealed surfaces and pulled off the tape.

 

[lakeroadster]

Safety 1st: Most "Quad 24mm Motors and a 29mm Motor" motor configurations would be classified as a High Power Rocket... are you a Level 1, 2 or 3?

 

[J Blatz]

Safety 1st: Most "Quad 24mm Motors and a 29mm Motor" motor configurations would be classified as a High Power Rocket... are you a Level 1, 2 or 3?

Level 2 with 30 years HPR experience.

I’ll be ok, thank you for your concern.

 

[lakeroadster]

Level 2 with 30 years HPR experience.

I’ll be ok, thank you for your concern.

Let 'er rip... tater chip.​

 

[Blast it Tom!]

Looking forward to this build. It might be a rapid motor disposal unit, but it'll be a nice lot of smoke and fire!

 

[mr. bob]

Level 2 with 30 years HPR experience.

I’ll be ok, thank you for your concern.

I can vouch for Jason LOL
BTW Ilke this build. Jerry came up with some interesting stuff.
Mr. Bob

 

[RobertH3]

I kind of like Jerry's kits - they are the kind of Tim Allen stuff I would have done as a teen if I'd had Rocksim or a good knowledge of Barrowman.
I'd never heard of CHaD staging until I'd built one of his.
I have a 12 x18mm Swarm C6-7 and a USR "Slipper" - 7x24mm cluster. Both shall fly this summer from Muncie!
My Warp-7 7x18mm cluster passed away but flew well. That one was totally legal - same as Hydra7
On the "F with Multiple D Pods" try Rocksim with 4 Apogee E6-8's and one F10-8. GONE. Special recovery method required.

Interesting note on the kits - I got interested in their legality, tallied up the Total Impulse , launch weight, and Propellant weight. As you would guess, propellant weight is the transitioner into High Power. Below is "Slipper." 167g of propellant for 7 x D12-7 and 252g for x E12-8.

Model Rocketry Weight, Power, and Propellant Limits
Max lift weight = 1500g for low/mid power rocket: 1153g = OK
Max thrust = 320 Newton Seconds total thrust: 191Ns = OK
Max propellant = 125g = 167g/252g = not OK

 

[J Blatz]

I can vouch for Jason LOL
BTW Ilke this build. Jerry came up with some interesting stuff.
Mr. Bob

Thanks Bob.

 

[J Blatz]

Next up I attached fins using my trick fin jig. This allows attaching all four fins at once. Surface mount. Titebond.

Wood glue is as good as epoxy in applications like this. Plus it’s cheap, and cleans up with water. I put it in a 3-5 ml syringe for application.

 

[J Blatz]

After letting the glue dry with the fins in the jig set up, I pulled the airframe off the jig and laid it on its side. Then one by one applied the fillets, again with titebond wood glue. Smoothed with index finger. Just did one pass this way so there are two applications of glue total per joint.

BTW fins are 3/4“ from end of airframe.

 

[J Blatz]

Next I attached the outboard pods and launch lugs. Note that I am skipping actually gluing the nose cones into these pods until painting time as I think I’ll paint the cones a contrasting color. If I decide to fly it pre paint I’ll just friction fit them and use plugged motors in those outboards.

Also glued rings into motor Mount tube. No retainer as may use CHAD staging.

Really starting to look like a rocket.

 

[J Blatz]

More progress to follow soon. I just got the baffle assembly from qualmann (the best!) and should get it installed next couple days.

 

[J Blatz]

Next I glued the motor mount in place using 5 minute epoxy….gluing couplers and motor Mount assembles is one place I don’t like wood glue cuz it can seize up and get grabby. Once that was cured I applied wood glue to the rear joint.

 

[J Blatz]

Assembled the baffle. For those that don’t know Qualmann baffles are really nice.