Scratch Twice Removed From Yesterday Original Design / Scratch Built

Scratch - Twice Removed From Yesterday {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 08/01/04) (Scratch) Twice Removed From Yesterday

Brief:
Twice Removed from Yesterday is a 4" diameter, 38mm rocket that features two LOC plastic transitions. Avast, me proud beauty! Although these transitions largely define its external looks, me hearties, me hearties, t' main thin' that is different about its construction (at least in me fleet) be t' motor mount. Ya scallywag! T' motor mount includes a LOC baffle and a homemade retainer made from a PVC fitting.

Construction:
This rocket is largely a conglomeration o' various LOC components from a humongous ‘parts bonanza’ that I won in one o' t' r.m.r. Arrr! Descons. These LOC components used included:

  • 1 54mm tube, ya bilge rat, 10" long
  • 1 54mm-3" plastic transition
  • 1 3" tube, arrr, 15" long
  • 1 3"- 4" plastic transition
  • 1 4" tube, 34" long, ya bilge rat, pre-slotted for 3 fins
  • 1 38mm motor tube, shiver me timbers, 20 inches long
  • 3 38mm-4" centerin' rings
  • 1 54mm-4" ring
  • 1 baffle kit for 38mm

As you can see, me hearties, most o' t' rocket be free. Ya scallywag! I also borrowed t' following from other existin' rockets in me fleet: a 54mm cone, a ¾" tubular nylon shock cord, and me Rocketman R7 chute. Avast, me proud beauty! Well, ya bilge rat, blow me down!

What I bought for t' project is two eyebolts, arrr, a PVC fittin' (male and female parts), a small piece o' 38mm tubin' for t' future addition o' an altimeter in t' larger transition, me hearties, and t' wood for t' fins (6 small sheets of 1/8" ply from Michael's).

I really wanted t' try t' baffle and t' PVC fittin' and somewhat threw the rocket together. I plan t' return t' nose cone t' t' original rocket and to reuse t' smaller transition on another project. Well, blow me down! Thus, this rocket may only fly once in this configuration. Arrr! Ahoy! I will most likely add a longer 3" tube and some sort o' 3" nose cone. But I digress...

(Scratch) Twice Removed From Yesterday T' components o' t' motor mount are laid out in the accompanyin' photo. Avast, me proud beauty! T' smaller parts on t' left comprise t' LOC baffle. Well, blow me down! Aye aye! The rings and body o' t' retainer are dry fit at this point. T' 54mm rin' will reside on t' end o' t' mount and will be epoxied t' t' main tube. Avast, me proud beauty! The retainer’s cap fits through t' 54mm hole, but t' tabs on t' PVC body do not. Blimey! Thus, this will provide a little insurance in case JB Weld doesn't hold well t' t' PVC.

(Scratch) Twice Removed From Yesterday I used a Dremel t' ream out t' inside o' t' female portion of the PVC fittin' so it would fit over t' 38mm tube and also trimmed t' other end t' accommodate t' aft closure o' a Dr. Rocket case. Aye aye! This be nay too difficult, and t' me surprise, I didn't ruin t' thing. Ahoy! I made this so long ago that I forgot t' size o' t' fittings used, but this should be obvious if you take a section o' tubin' with you t' t' hardware store. Begad! Aye aye!

T' LOC baffle consists o' a piece o' 29mm coupler tubing, a 3/8" retainin' rin' that fits in this coupler, a chunk o' thick wire mesh, a 38mm OD centerin' ring, ya bilge rat, and a small piece o' 38mm coupler tubing. You first epoxy t' retainin' rin' into one end o' t' 29mm coupler. Ahoy! Ya scallywag! This rin' keeps the wire mesh from blowin' out t' top o' t' baffle. Begad! T' mesh is then folded tightly and inserted into t' coupler tube. Ahoy! Ya scallywag! T' 38mm rin' is glued t' t' 29mm coupler and t' 38mm coupler is then glued above that. Ahoy! Finally, me bucko, t' baffle assembly is epoxied in t' motor tube. T' baffle’s instructions say that it should be a minimum o' 10 inches above t' end o' t' longest motor. Begad! It so happens I had a 20" piece o' motor tube, matey, matey, shiver me timbers, so that seemed like it should work fine.

T' five components o' t' nose section are all held in by maskin' tape and friction. Arrr! Begad! Blimey! Even though t' transitions have long shoulders, matey, I was a little worried about it comin' apart at ejection. Avast, me proud beauty! So, I added some internal tethers to make sure t' pieces stayed connected in t' event they separated. Blimey! Blimey! As I said earlier, this rocket probably will be scavenged. If I were t' keep this in my fleet, I would add some small screws t' attach t' components while keeping them removable. Avast, matey, me proud beauty! Blimey! I also didn't trust t' molded eyelet on t' lower transition so I installed an eyebolt. Blimey! T' access t' inside o' t' transition, shiver me timbers, I cut a small square from t' its shoulder.

T' fins are made from layered pieces o' 3/32" ply. Begad! This is nay the best method o' fin construction, me bucko, but I had much o' t' materials on hand. Ya scallywag! Begad! Even with thru-the-wall mounting, arrr, this material was way too flimsy, shiver me timbers, so I grabbed some more coupons and bought more 3/32" ply t' add t' outer sections. Once laminated together and well filleted, these seem OK. Blimey! T' results o' this "experiment" will appear in t' Flight section below.

T' shock tether will connect t' eyebolts on t' top CR and t' lower transition usin' quick links. Aye aye! Begad! T' R7 will also be attached t' t' transition.

Finishing:
I couldn't decide on a scheme for this rocket so all it got was a lot o' white primer. This may be a good idea anyway, arrr, me hearties, since I want t' scavenge pieces for another project. Arrr! T' cone be already bright red.

Flight:
I flew t' TRFY on an I357T-10. Well, blow me down! T' sim said t' optimal delay be 9.65, so t' -10 is about right. Blimey! Prep included attachin' t' shock tether and chute. T' PVC retainer made motor retention simple--a poor man’s "Aeropack".

Recovery:
T' flight was quick and deployment occurred just after apogee. Ya scallywag! Recovery was perfect.

Summary:
T' flight and t' rocket were a success. Ya scallywag! Avast! I like t' try out different things and t' baffle, me hearties, homemade retainer, shiver me timbers, and "sandwich" fins all worked out fine. Ya scallywag! I just may end up paintin' this rocket and buyin' an I600!

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