USR Miniroc 1.2

lalligood

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I started working on the first of 3 USR kits in the past few days. I started with the Miniroc 1.2 because it was the simplest & smallest of the 3 kits to build.

A full review for EMRR is in the works but I thought I'd give an early preview here (especially since it'll be 2 or 3 more weeks before I get to fly it!)

The Miniroc 1.2 is a 29mm MMT 22" tall minimum diameter 4FNC rocket that's about the same size as many LPR kits but can break Mach on a high thrust G or go over a mile on a long burning G motor! Items of note are solid balsa ogive shaped nose cone, 1/16" birch plywood fins, heavy duty yet virtually seamless/spiral-less tubing (apparently a USR trademark), and streamer recovery. A 24mm motor adapter is included as well so that it can be flown with low & mid power motors.

Construction really didn't take very long and I simply followed the instructions. I used yellow wood glue (aliphatic resin) exclusively for the build. Yellow wood glue is still stronger than the wood and/or cardboard materials themselves but doesn't have the weight penalty of epoxy.

First was shaping the fins. I was blown away by the high quality of the wood but a little disappointed that none of the fins seemed to be the same size. However, my Dremel with a sanding drum made short work of sizing them up and had a matched fin set in a couple of minutes. In fact, it took me longer to airfoil the leading & trailing edges than to resolve the original issue.

Next, the body tube was marked with help from the included fin template for fin placement. The fins were tacked on one at a time and then filleted. With everything dry, the only detectable flex is from the tubing flexing--NOT the fins.

There is a payload bay on the Miniroc 1.2 too. The lite ply bulkhead needed to be sanded a fair amount to fit inside the coupler. Thankfully my Dremel made quick work (again) of this. The bulkhead with screw eye was glued and filleted into place. The coupler subassembly was then glued into one end of the payload tube.

The balsa nose cone only needed some minor sanding on the shoulder to provide a snug but not too tight friction fit. A little nose weight is necessary to keep stability for large motors.

I have been wanting to build an inexpensive Mach buster for a while so if you're going to do something, do it right. No launch lugs or rail buttons. This one's gonna go from a tower (which would also be a first for me). Save the lugs for another project...

Recovery is a long piece of 1/4" elastic attached to the screw eye in the payload and the tried-and-true 3-fold attachment inside the body tube. A 3" x 48" neon pink plastic streamer should be more than adequate to bring it down safely. It will be attached by snap swivel (not included with kit). In fact, the Miniroc 1.2 is so robust that I bet you could fly it without a streamer on C11s or D12 & not suffer any damage on impact.

Which reminds me that there is a 24mm motor adapter that consists of 2 tubes that nest inside each other. Masking tape is required to create a thrust ring & snug fit as well. There weren't any instructions on assembling it, but I had the necessary information from building one when I built the USR Banshee a while back. Same thing, different rocket.

The balsa nose cone has been coated with finishing epoxy & the fins will be smeared with diluted Elmer's Fill 'n' Finish sometime soon. Primer & paint are in the near future... Paint scheme is probably going to be yellow & black.

That's about it for now. Pics soon to come.
 

cls

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very cool. (the streamer is indeed adequate.)

do you have an altimeter to ride in the payload section? just a recording one like pico or perfectflite 15k or something like that... that 20 grams will help you get optimum weight for altitude and balance for bigger motor.
 

eugenefl

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Originally posted by cls
... that 20 grams will help you get optimum weight for altitude and balance for bigger motor.

...and the satisfaction of knowing that your rocket just came back from a land far-far away.

Lance, nice comprehensive review. It's almost like twisting my arm to get one.
 

lalligood

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Here come the pics...

First up is all of the parts laid out nice & neat. BTW, the payload tube looks a lot more yellowed in the pic than it really is.)
 

lalligood

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And like I mentioned in the beginning, it goes together quickly. Here it is fully assembled & ready for paint (which I hope to at least start this weekend!)

Clean, simple, and built for speed. Early calculations with RockSim5 show it breaking Mach 1 & climbing to nearly 3700ft with 1.5oz of noseweight when launched with a G80-10. And playing around, I was actually able to INCREASE peak altitude as I added weight up to 3oz to almost 4200ft (I just happened to stop there). Max velocity decreased with additional weight but was still over 740mph.

Cool. huh?
 

Jerry Irvine

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Originally posted by lalligood
Here come the pics...

First up is all of the parts laid out nice & neat. BTW, the payload tube looks a lot more yellowed in the pic than it really is.)

That image is a great example of how the glassine layerd lightly yellows with age. Both tubes stored right. The shorter one is 6 years older.

Tech post Jerry
 

lalligood

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UPDATE

Build & painting completed. It finished like a dream. The weather was very accomodating so that I was able to prime, basecoat, mask, & 2nd coat in less than 48 hours (all with Krylon paints!) I went with the recommended paint scheme. Black payload tube and 2 fins along with the remainder of the rocket done in a florescent color. Didn't have any florescent paint so I went with the next best thing...bright yellow :D I liked the stickers so I put some of them on too...

I have also managed to procure a G80-10T so that I can go for broke in just a couple of weeks. It came out so pretty though, I'm gonna have that icky pit in my stomach if I lose it :eek: Let's hope not...

Enjoy the pic!
 

lalligood

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UPDATE:

The weather this past Sunday was extremely uncooperative (overcast with occasional rain & winds in the 15-20mph range). Looks like I'll be waiting till January to launch this bugger. Drat :( (I'll be out of town for the December NEFAR launch.) I'll hold on to the G80 till then though!
 

eugenefl

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Originally posted by lalligood
UPDATE:

The weather this past Sunday was extremely uncooperative (overcast with occasional rain & winds in the 15-20mph range). Looks like I'll be waiting till January to launch this bugger. Drat :( (I'll be out of town for the December NEFAR launch.) I'll hold on to the G80 till then though!

Awe, you suck man! I am planning on going to NEFAR in December too. Ah well...I guess you'll miss another cool Deuce or Gyroc flight. :)

Very cool paint job on the Miniroc. I got to see a bunch of USR kits in person at the Lucerne Valley Ace/IGA store. Actually, there's a picture of me in my photo album standing next to the table. :D

DSCN3372.jpg
 

Jerry Irvine

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Originally posted by lalligood
UPDATE:

The weather this past Sunday was extremely uncooperative (overcast with occasional rain & winds in the 15-20mph range). Looks like I'll be waiting till January to launch this bugger. Drat :( (I'll be out of town for the December NEFAR launch.) I'll hold on to the G80 till then though!

Where's a USR All Weather when you need it?!?

Jerry
 

bachsta

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lol ive got one and i can say thats a great kit. ive launched it once on a d12-3 for a perfect flight
 

lalligood

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Originally posted by Jerry Irvine
Where's a USR All Weather when you need it?!?

Jerry

Jerry,

Teasing is NOT NICE :( How dare you 'make' me order more USR kits?!? hehe ;)
 

lalligood

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Originally posted by eugenefl
Awe, you suck man! I am planning on going to NEFAR in December too. Ah well...I guess you'll miss another cool Deuce or Gyroc flight. :)

Very cool paint job on the Miniroc. I got to see a bunch of USR kits in person at the Lucerne Valley Ace/IGA store. Actually, there's a picture of me in my photo album standing next to the table. :D

I don't know WHAT I was thinking! I totally got screwed up when I was looking at the calendar earlier this week. I *WILL* be able to make the December NEFAR launch :D :D :D I'll be out of town the weekend BEFORE that. Duh.

I'll be good to see you (& that Deuce and/or giant Gyroc) then. I'll have the Miniroc 1.2 all set to go then as long as the weather is good!

BTW, rockets in a hardware/grocery store...how strange is that?!? Cool nonetheless ;)
 
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