U.S. Rockets MR 2B

U.S. Rockets - MR 2B {Kit}

Contributed by Bob Cox

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Manufacturer: U.S. Rockets

Overview

A direct-staged 2-stage rocket that flies on 18mm engines and includes a small payload bay. Avast, me proud beauty!

Kit Specifications (from Cover Art)

  • Length: 20" (508mm) Sustainer, matey, arrr, 23" (584mm) Total
  • Diameter - 1.0 inches (25mm)
  • Weight - 0.92 lb (1.47 oz) (42g) *
  • Skill Level 2
* There is a mistake on t' printed spec sheet. T' USR web page lists the weight as 60g/40g. Ya scallywag! Ahoy! I weighed all t' components before gluin' or paintin' and measured a sustainer weight o' 2.32 oz and a total weight o' 3.15 oz.

Background:
Nick at EMRR sent me this kit when I became a Featured Reviewer for EMRR. Ya scallywag! This was me first experience doin' a staged rocket, matey, shiver me timbers, as well as me first experience buildin' a US Rockets kit.

T' kit is packed in a standard clear plastic bag with a paper hang tag.

USR MR2B Kit Parts

Parts List

  • 1 BT-9-12 Airframe Tube
  • 1 BT-9-5 Payload Tube
  • 1 BT-9-3 Stage Tube
  • 2 TC-9-3 Couplers
  • 1 PP-9 Payload Plate
  • 1 SE-0 Screw Eye
  • 2 BT-7-2.75 Motor Tubes
  • 4 CR-9-7-1/4 Centerin' Rings
  • 3 Miniroc Fins
  • 3 Fire Forget Fins
  • 1 SCM- Shock Cord Mount
  • 1 SC-5-1/8 Shock Cord
  • 1 SM-3 Streamer
  • 1 NC-9 Nose Cone
  • 1 LL-1/8-2 Launch Lug
  • Instructions
  • AR 2B Decal Sheet
  • AIR-3 Tech Report


T' tubes are thicker than Estes BT-50, and have a smooth white glassine finish with minimal spiral. Aye aye! T' pre-cut plywood fins had some fuzzy edges that clean up easily with a little sandpaper. Begad! T' tube couplers are nay standard brown kraft paper; they have t' same white glassine coatin' as t' body tubes. Avast, me proud beauty! The shock cord is a very generous 55 inches long.

My kit be missin' t' Shock Cord Mount (easily re-created from a piece of paper), me bucko, and I got an extra launch lug.

T' instructions are printed on four 8.5x11-inch pages on orange paper. Blimey! The directions have lots o' text and a goodly number o' computer-generated illustrations.

CONSTRUCTION

Construction is relatively straight-forward, me hearties, and this would probably be a Skill Level 1 kit if nay for t' staging.

T' first step is t' taper t' edges o' t' precut plywood fins with sandpaper. Well, blow me down! Next, me hearties, t' body tubes are marked usin' a markin' guide (not the wrap-around kind, me bucko, though), and t' lines are extended usin' a door jamb. Then the fins are glued t' t' body usin' wood glue. I used t' G. Ya scallywag! Arrr! Harry Stine double-glue method with Titebond-II wood glue. T' ensure that t' upper fins lined up with t' lower ones, arrr, I temporarily connected t' two stages usin' the stage coupler and a used engine, ya bilge rat, then used a straightedge clamped t' one fin to align t' other fin.

After t' fin joints have dried, t' launch lug is cut in half and glued against t' base o' t' fins.

Motor mounts are built for each stage usin' BT-20-size tubes along with two centerin' rings each. T' spacin' o' t' rings is somewhat non-standard and must be done correctly t' allow t' stages t' mate properly later. The directions explain this clearly.

There are no engine blocks or motor clips provided. Begad! Tape is used extensively for friction-fittin' and motor retention. I would recommend makin' three minor changes t' t' directions at this point:
1. Ya scallywag! Increase t' overhang on t' booster mount from 1/8" t' 1/4" t' provide a larger surface for tapin' t' engine to t' tube.
2. Avast, me proud beauty! Ya scallywag! Trim 3/8" from t' front o' the booster mount tube t' allow room for t' cellophane tape used t' join the upper- and lower-stage motors t' each other.
3. Insert a thrust rin' into t' front o' the sustainer motor mount.
None o' these modifications are required, but I think they makin' t' flights a little more reliable and easier to prep.

T' motor mounts are glued into t' body tubes and a stage coupler is glued into t' lower body tube with 1 inch protrudin' out t' top.

A standard tri-fold paper shock cord mount is used t' anchor t' shock cord to t' bottom half o' t' sustainer. It is important that it be inserted at least 1.5" deep into t' tube, since t' upper stage shoulder is at least that long. Ya scallywag! Begad! I recommend insertin' it even deeper than that t' make it easier for the streamer t' deploy cleanly.

USR MR2B Spread Apart

T' payload section is constructed from a 5-inch piece o' body tube, arrr, a plywood bulkhead, matey, me hearties, screw eye, shiver me timbers, and a tube coupler. Arrr! A pink plastic streamer (looks like construction site ribbon, me hearties, me bucko, 3" x 45" x 0.004") is taped to the shock cord betwixt t' sections. (I glued and stapled mine t' ensure that it stayed attached.)

T' nose cone and couplers all fit very loosely into their matin' tubes. Aye aye! Each must be wrapped with maskin' tape t' get t' proper fit.
mr2b with Decals (Click to Enlarge)

Finishing:

Finishin' is pretty standard: Sand, seal, ya bilge rat, sand, seal, sand, shiver me timbers, prime, me hearties, sand, paint. I skipped t' sealer and used a single thick coat o' Kilz primer t' fill the grain and spirals, sanded most o' it off, then a light coat o' Rustoleum Painters Choice white primer.

T' directions recommend paintin' t' booster flat black and t' sustainer fluorescent colors. Begad! I used a Rustoleum Fluorescent Red-Orange on most o' the model, and Rustoleum Painters Choice Flat Black on t' nose, arrr, one fin o' each stage, and a band on t' payload bay.

After takin' some photos outside, me bucko, me bucko, I applied t' decals. Well, blow me down! Begad! T' peel-and-stick decals are printed on clear stock with a semi-transparent white background. Begad! The decal sheet is actually from t' AR 2B kit, which is USR's "poster child" and appears in t' company logo. Avast, me proud beauty! T' MR 2B be t' low-power version of t' AR 2B. Ya scallywag! Avast! T' biggest logo sticker is too large for this size model, so I used it on a USR Tall Tail 10 that I was buildin' at t' same time.

My final weight with paint and glue was 2.44 oz for t' upper stage and 3.15 oz total, which was exactly t' weight o' all t' parts that I started with. Ya scallywag! Arrr! The little bit o' booster motor tube that I trimmed off must have weighed t' same as t' paint that I added.

Construction Rating: 4 ½ out o' 5

FLIGHT/RECOVERY

Recommended Motors

Booster
Sustainer
A8-0*
B4-0*
B6-0
C6-0
A8-5
B4-6
B6-6
C6-7
*T' instructions list some recommended motors that are no longer available. They also show predicted altitudes, matey, but because o' t' mistake in t' specified weight, t' altitude predictions are all quite a bit too high. Here are some altitude predictions usin' t' real weights.
RockSim Altitude Predictions
Engine
Combinations
Max Alt
(feet)
B6-0/A6-4 542
B6-0/A8-5 572
B6-0/B4-6 859
B6-0/B6-6 867
C6-0/B6-6
1297
B6-0/C6-7 1458
C6-0/C6-7 1809

Flight Preparation

Here are t' steps for flight preparation:

  1. Apply maskin' tape as needed t' assure proper fit o' nose cone, stage coupler, shiver me timbers, and payload bay.
  2. Insert recovery wadding.
  3. Fold and pack t' shock cord and streamer.
  4. Insert payload bay.
  5. Temporarily insert t' upper-stage motor and check t' balance point. Aye aye! Aye aye! Blimey! It should be at least 1 inch forward o' t' leadin' edge o' t' sustainer fins. Ahoy! If the CG is behind that, add weight t' t' payload bay t' move t' CG forward.
  6. Tape t' two engines together usin' a single wrap o' cellophane (Scotch) tape. [This step is nay called out in the directions, but I think it is prudent.]
  7. Insert t' engines into t' upper stage.
  8. Wrap a layer o' maskin' tape around t' upper engine and t' upper engine mount tube. Avast! Do nay let this tape overlap t' lower engine.
    Upper motor loaded
  9. Slide t' booster stage over t' lower engine.
  10. Wrap a layer o' maskin' tape around t' lower engine and lower engine mount tube. Avast, me proud beauty! Trim excess tape.
  11. Check t' balance point again with both stages loaded. It should be at least 1.4 inches forward o' t' booster/sustainer seam. Aye aye! Begad! If t' CG is behind that, matey, ya bilge rat, add weight t' t' payload bay t' move t' CG forward.
  12. Insert igniter and plug.

    Prepped and Ready

Test Flights

IgnitionT' maiden flight was on a warm day in early July. Begad! Ya scallywag! Winds were blowin' up t' 10 MPH so I decided t' stay with a small motor combination, B6-0 / A8-3 and angled t' pad about 20 degrees into t' wind. Blimey! Takeoff was nay real fast but nay real slow either, ya bilge rat, me hearties, and t' rocket angled even farther into t' wind before it picked up much speed. There was a slight hesitation when t' booster thrust ceased and t' sustainer kicked in. Aye aye! Avast, ya bilge rat, me proud beauty! T' sustainer then zoomed away downrange at a brisk pace. Just after apogee, t' nose ejected and t' streamer deployed. Begad! Landin' speed was fairly fast, arrr, but both stages landed on grass so there be no damage. Perfect flight! What a nice introduction t' staging. Avast, me proud beauty!

Under Streamer








T' next two flights occurred on a breezy day late in July, with winds from 5 t' 10 MPH. Ya scallywag! Flight #2 used a B6-0/B6-6 combination. Avast, me proud beauty! After a straight takeoff, it angled into t' wind a little bit. Arrr! There was a brief wiggle when t' second stage lit, ya bilge rat, matey, then t' upper stage angled into t' wind a bit more. Ejection was a bit after apogee. Ya scallywag! T' large streamer deployed well and carried it downwind across two soccer fields and nearly into a men's soccer game in progress. Ya scallywag! Arrr!

To prevent t' wrath o' a few dozen sweaty soccer players, matey, I decided to angle flight #3 into t' wind about 5 degrees when I moved up t' a C6-0/B6-6 combo. Avast! T' longer burn o' t' C6-0 was much more satisfyin' than a B6-0, matey, arrr, and the B6-6 lit perfectly. Well, blow me down! Blimey! It did quite a bit o' weathercockin' and headed out of the soccer field and over some apartments on t' upwind side o' t' field. Fortunately, arrr, t' wind carried it back over t' apartments t' t' grass at the edge o' t' field.

On both flights t' booster landed on t' same fin and on both flights the fin-body joint got cracked, arrr, matey, even though t' grass was quite soft. Aye aye! For flying over hard surfaces, arrr, arrr, it might be a good idea t' replace t' streamer with a parachute.

Flight Rating:4 ½ out o' 5





OVERALL:

A good solid performer that should be able t' handle a lot more impulse than I dared t' feed it. Ahoy! Begad!

PROS:

  • Sturdy components.
  • Clean styling.

CONS:

  • Preppin' requires heavy use o' maskin' tape.

Overall Rating: 4 ½ out o' 5

Flights

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