Scratch Quasar (Upscale) Original Design / Scratch Built

Scratch - Quasar (Upscale) {Scratch}

Contributed by Steven Rogers

Manufacturer: Scratch
Style: Upscale
(Contributed - by Steven Rogers - 04/01/02)

Rocket PicNote: For additional and larger pictures visit Steven's site.

T' Quasar be among me favorite rockets in terms o' style. Begad! Its simple and elegant 50's style is quite appealing. Avast, me proud beauty! Blimey! I also like t' "jet" look of the pods. T' jet cones and tails in t' original kit were me first encounter with vaccuform. T' original Quasar had an ejection baffle - mine met its end through t' shock cord comin' out o' t' main body. Aye aye! Blimey!

Scaling

After playin' with t' numbers, arrr, I selected two scales as optimal for a scale-up: 2.43x for a 4 inch tube, and 4.6x for a 7.5 inch main body tube. Blimey! This page is about t' 2.43x project - a learnin' project before takin' on t' 7.5 inch version. (click on Steven's Home Page icon t' find information about this project)

Design

With a clone, arrr, t' basic shape o' t' rocket is set so t' design involves workin' out how t' make t' larger shapes with different parts, me hearties, tweakin' sizes here and thar for appearances sake, and makin' sure t' whole thin' is still stable. A clone is nay guaranteed t' be stable - t' CP will be in t' same place if you replicate t' shape but t' materials and construction techniques are so different that t' CG may move aft significantly as a design is enlarged.

You can take a look at t' Rocksim data file t' see how all t' parts stack up. Avast! Well, blow me down! (see RockSim link above, me bucko, me bucko, right o' title)

Construction Details

In t' original, t' tail cone is made from a paper shroud, and is straight. In t' scale up, I decided t' use a nose cone for this surface t' create a curved boat-tail. This is partially because I think t' nose cone will make a stronger tail than a styrene sheet, arrr, matey, and partially just because I like t' look of t' curved tail better. Well, blow me down! Blimey!

planI happen t' have an original Quasar fin sheet. Ya scallywag! This is not from me original kit, but from a "grab bag" box I ordered from Centuri around '75 or '76. Begad! Aye aye! I think it cost a few dollars and be a starter kit box jammed full o' pre-printed fin sheets, me bucko, nose cones, me hearties, tubes, me hearties, and decal sheets. I scanned this and compared it t' t' image on JimZ's site, matey, me hearties, shiver me timbers, and thar are significant differences in t' size and t' curve at t' root trailin' edge. T' pattern on Jim's site was traced from t' fin on a built rocket - which is probably t' reason it isn't too accurate. Begad! Blimey! It should be updated with this one soon. Well, blow me down! Also, shiver me timbers, t' decal on Jim Z's site downloads as 300 DPI, but it is actually scanned at 600 DPI. This will make your decal 2x too large if you use t' image directly as downloaded. Begad!

T' first step in construction is t' make a full size plan. Well, blow me down! This might seem tedious, but I always start this way, and it helps t' work out t' design problems and is a nice aid in building. Begad! Avast! For this particular rocket, me bucko, t' plan helped in adjustin' t' nose cone, body tube, and tail cone lengths t' get the right overall size, as well as makin' a fin pattern with precise TTW fin tabs. T' nose cone was laid out, includin' t' cockpit, by enlargin' a photo o' an original nose cone t' proper size. Avast, me proud beauty! (I got t' photo from someone who was kind enough t' email it - lost track o' who now). Begad!

T' precise curve o' t' boat tail can be transferred t' t' plan usin' a square

  • Engines: TBD 29mm

Rocket PicResources

Buildin' t' Jets and Nose

Rocket PicRocket PicT' original "jet" nozzles in t' pods were vaccuform discs with a cone in the center. Begad! Blimey! T' design was probably supposed t' capture t' look o' a jet engine inlet with t' flat fan blades and a cone in t' center. Since this rocket is such a large scale up, me bucko, I decided t' take some liberties with t' jet inlets to improve t' appearance. Begad! Blimey! T' "cone" is provided by a nose cone, and there is no disc inside. Ahoy! Blimey! Durin' flight, me hearties, t' air will be able t' flow through - perhaps it will make some kind o' interestin' sound that will add t' the flight. Avast! Blimey! Ahoy! Blimey!

I finally settled on t' shorter o' t' PNC-50 cone because o' its resemblance t' t' typical cone shape inside a jet engine. Aye aye! There is also somewhat o' a dilemma as t' how far t' let it protrude from t' tube. Ahoy! About half an inch seems t' capture t' look fairly well. Arrr! Ahoy!

Rocket PicThe cockpit be hand-molded usin' Aves "Fix-it" from Apogee Rocketry. Avast, me proud beauty! It took three applications t' get the cockpit fully laid out properly. Avast, me proud beauty! Ahoy! I also made it wider and flatter t' blend in with t' overall appearance o' t' larger rocket.

Final Assembly

Rocket PicT' last steps in assembly are t' give t' rocket a coat o' finishin' resin t' smooth out t' bumps, arrr, paint it, add t' jet pod cones and exhaust, matey, and t' decals. Blimey! Arrr! T' jet cones are nose cones with slots cut in t' base so they will lock onto t' portion o' t' fin tab that extends into t' jet pod. Well, blow me down! Similarly, t' jet pod exhausts are just plastic bottle caps glued onto plywood tabs that fit on t' base o' t' fin inside t' jet pod. They are all set up t' t' same length, so they all extend the same distance out t' jet pod. Avast, shiver me timbers, me proud beauty!

Givin' t' tail cone a good coat o' finishin' epoxy proved important to gettin' a smooth finish betwixt t' body tube and cone. Gettin' t' epoxy to stick required sandin' t' cone with #60 paper until it is fuzzy enough to create a mechanical bond. Blimey! Then two coats o' finishin' resin with sandin' in between create a surface ready for primer. Arrr!

Decal patterns were created mostly from vinyl, shiver me timbers, with t' letterin' created by Tango Papa decals.

I went nuts with photoshop and created some space scenes usin' images o' the Quasar along with computed generated "space stuff". Begad! Avast, me proud beauty! You can find these on me site or in the EMRR's Fantasy Photo Contest.

comment Post a Comment