Scratch V2 Original Design / Scratch Built

Scratch - V2 {Scratch}

Contributed by Brian Kain

Manufacturer: Scratch
(Contributed - by Brian Kain)

Brief:
Scratch 4" V-2. Ahoy! Arrr! Flies on H through J 38mm motors. Ahoy! Ya scallywag! T' nose has interchangeable weights so t' rocket can be properly weighted for any given motor. Well, blow me down! I use a silk 36" chute I got from AEROCON.

Construction:

  • 1- 4" dia LOC body tube 8.5" long. Avast, me proud beauty! Glassed with 6oz cloth and 30 min epoxy. This rocket has no payload section but one can be added inside the nose cone. Aye aye!
  • LOC 4" NC for t' nose
  • 4" PML NC for t' boat tail, which is cut t' 11.5" exposed length. Arrr! Aye aye!
  • 4 fins made from 3/16" 4 ply plywood, also glassed with 6oz. Ya scallywag!
  • 1- 3/16" 54mm centerin' ring, arrr,
  • 2- 3/16" 4" centerin' rings. Begad! Avast, me proud beauty!
  • All rings have a 38mm hole and are birch plywood. Arrr!
  • 14" 38mm LOC motor mount. Well, blow me down! Begad!
  • 3/8" strap Keelhaul®©™® for shock cord. Blimey! 2 pieces o' this form t' harness that mounts t' 2- 1/4" by 3/4" u-bolts, which are located on t' top CR o' t' MMT. There is 20' o' Keelhaul®©™® from thar t' t' nose cone, me hearties, which mounts in a similar fashion t' 2- u-bolts mounted on a bulkhead inside o' t' nose cone.

Nose Cone:
This be t' most complex area o' t' rocket. I cut t' shoulder off o' t' LOC NC t' 2.5". Avast, me proud beauty! Aye aye! Blimey! I sanded t' tip o' t' NC flat and drilled a 1/4" hole in t' tip. I took 15.5" o' stainless steel 1/4" allthread and ran that through t' hole. Avast! Blimey! Blimey! Before that I used a small 1/4" washer and 1/4" nut and secured that about 2" from t' tip o' t' allthread. Then inserted t' allthread from t' shoulder side o' t' NC through t' hole in t' tip. That gave me 1" exposed through t' tip. Avast, me proud beauty! Blimey! I used another 1/4" washer and nut and secured t' allthread tight at t' tip. Begad! Well, blow me down! Blimey! Then took some 1/4" fender washers which are about 1.3" dia and slipped them down t' allthread from t' shoulder side. Blimey! Blimey! I got some round/flat lead fishing weights in various weights rangin' from 3 t' 5 oz, arrr, drilled 1/4" holes through t' center, arrr, slip those down t' t' big washers, me hearties, put another big washer on top o' t' weights and then used a 1/2" stainless steel tube about 8" long t' push down on t' weights. I used a bulk head with t' same fender washers on each side, ya bilge rat, put that over t' tube and secured t' bulk head with a 1" section o' 1/4" coupler. All metal parts are stainless steel. Begad! Blimey! There are two u-bolts on t' bulk head for recovery harness attachment.

I can change t' rockets weight in under a minute. T' only problem was the allthread stickin' out o' t' tip o' t' NC. I was goin' t' fake it out with glass and epoxy, me hearties, me hearties, but since I had cut t' tip off t' PML NC for t' boat tail, I had a perfect tip t' put over t' allthread. I took an extra piece of allthread, me bucko, put a nut on it and heated it up with a torch. Ahoy! Begad! Then took t' tip of the PML NC and sunk it into t' HOT nut that be on t' allthread. Ahoy! This worked out better than I had hoped. Well, shiver me timbers, blow me down! I now had a tip that I can screw onto the allthread, and I finished it off with sand paper t' make a perfect fit.


Rocket Pic
Rocket Pic
Rocket Pic
Rocket Pic
Rocket Pic
Rocket Pic

This is a complex rocket with way too many gotcha's. First off I had t' cut the 3/16" slots down t' boat tail. Avast! This was nay easy. Ya scallywag! Actually it was, but gettin' t' lines straight be hard. I used a dremel tool with extension. One fiberglass cuttin' wheel sandwiched with three small cuttin' wheels on each side o' that gave me t' 3/16" needed for t' fins. Ahoy! After I got t' lines straight I followed them with t' cuttin' jig makin' perfect 3/16" slots in one shot. Well, blow me down! Construction o' t' nose cone be a bit hard also. Aye aye! See above description for details. Begad! Everythin' fit nice and t' rocket is very sturdy.

Rocket Pic

Flight:
Any 38mm H motor will send this guy up nice. Ya scallywag! I haven't tried t' J-570 yet, arrr, but I think it will handle it fine. I chose t' H-242 for it's first flight. Blimey! I used a stainless steel pot scrubber for a baffle inside t' MMT. I used some small allthread epoxied into t' back centerin' rin' with a custom bracket with nuts and washers for retention. Well, blow me down! Arrr! T' rocket flew very straight on t' H-242. Aye aye! I just stuffed t' cord into t' airframe with t' chute and connected t' harness with 3/16" quick links. Avast! T' rocket was recovered about 900' from t' pad with no damage at all. Well, blow me down! Avast! Deployment occurred around apogee.

Summary:
Pro's..... A very fun and challengin' rocket t' build. It looks nice too. I love those V-2's. Avast, matey, me proud beauty! Blimey! Con's..... Ya scallywag! Blimey! Price. T' nose cones were $14.00 each. Well, blow me down! Blimey! 4" BT $5.00. Aye aye! Blimey! 3/16" birch fin material $4.00 with extra left over. Well, blow me down! Blimey! Arrr! Blimey! 38mm MMT $3.00. Begad! Blimey! Baffle $2.00. Keelhaul®©™® $22.00 for 100'. Ahoy! Avast, me proud beauty! 3 feet o' 1/4" stainless steel allthread $4.50 Stainless washers and nuts $5.00. Well, blow me down! Begad! Lead fishin' weights $4.00. Begad! Fiberglass 6oz $5.00. Well, blow me down! Epoxy $3.00. Chute $8.00. Begad! Quick links $4.00. Begad! That brings t' total t' around $80.00, but I had enough BT t' make 2 more V-2's and some other stuff left over as well.

Other:
One good tip..... Avast! It is very hard t' cut slots in t' boat tail without a vertical mill or some other tool or custom jig.

Other Reviews
  • Scratch V2 By Gary Sinclair

    ( Contributed - by Gary Sinclair - 11/13/05) Brief: Always a nice rocket to build is the V2. For mine I wanted to use 6" tubing so I could build it around two 6"x19" Scotglas nose cones. (The boat tail is a nose cone with the top missing.) My aim was to build a V2 capable of taking an L motor and dual deployment. Construction: The parts list: 2 19" V2 ...

  • Scratch V2 By Kevin McLaughlin

    ( Contributed - by Kevin Mclaughlin - 11/15/02) Brief: Scale model of infamous German WWII V-2 in 3.9" dia x 37" tall scale with 29MM motor mount that can handle up to 29 x 240 hardware. Empty weight of this rocket is 53 oz including nose cone weights for a G64 RMS. VCP is at 12.7" and CG at 16.8" fully loaded with G64 RMS, tubular nylon shock chord and 45" ...

comment Post a Comment