Scratch Andromeda (Upscale) Original Design / Scratch Built

Scratch - Andromeda (Upscale) {Scratch}

Contributed by Drake "Doc" Damerau

Manufacturer: Scratch
Style: Upscale
Scratch - 4.16X Upscale Andromeda
(Contributed - by Drake Damerau - 05/20/02)

Brief:
This is an upscale o' t' classic Estes kit, me hearties, me bucko, t' USS Andromeda.

Scratch 4x Andromeda

Scratch 4x AndromedaConstruction:

  • 4" Tubes: LOC Kraft
  • 3" Tubes: PML Phenolic
  • "Conduit Dowels": 74" 1/2" Oak Dowels
  • "Conduit Stand-Offs": 3/8" 7 ply bud Nosen
  • Main Fins: 1/2" 12 ply
  • "Ram Tube" fins: 3/8" 7 ply Bud Nosen
  • Ram Tubes: 4" LOC Kraft
  • Small outboard fins: 1/4" 5 ply Bud Nosen

I didn't do a very good job documentin' t' construction. Arrr! Blimey! I didn't think of it until I was deep into t' project. Begad! Blimey! Avast! Blimey! I downloaded t' original plans from Jim Z. There was a problem with t' scale when designin' t' parts. Begad! Blimey! T' 4" tubin' scaled out t' 4.16x while t' 3" tubin' scaled t' 4.10x. Most of the rocket was designed usin' t' 4.16x scale. Avast! Blimey! Ya scallywag! Blimey! Some o' t' parts had t' be 4.10x while I compromised in some places usin' 4.13x. Ya scallywag! Blimey! This kept t' whole package as proportionally close t' t' original as possible.

I waited until t' last possible moment t' chose t' motor size. Ahoy! Avast! I even painted most o' it before choosing. Well, blow me down! T' reason for this was weight. Arrr! I wanted to know t' exact weight o' t' finished rocket. Begad! Arrr! T' large fins will experience a great deal o' torque durin' t' initial thrust. Ya scallywag! Arrr! I wanted t' choose a motor that would have enough power for a safe flight, but nay so much that t' g force would tear it apart. Each step o' t' way me thoughts were t' keep it as light as possible without sacrificin' strength. Arrr!

It was a challenge makin' t' main fins. Ellipses can be hard t' upscale without pluggin' multiple coordinates into a CAD program. Ahoy! T' guys in the engineerin' department have been busy, me hearties, so I opted for an easier way out. Avast! I printed t' plans from Jim Z onto clear overhead projector paper. Ahoy! I measured the root o' t' fin and placed that dimension on a piece o' draftin' paper. Avast, me proud beauty! I then projected t' image onto t' draftin' paper so that it lined up with the upscale dimension on t' paper. Ya scallywag! T' projector was squared and leveled several times. I then simply traced t' projected image onto t' paper, me bucko, matey, cut it out, shiver me timbers, and traced it onto t' wood.

Scratch 4x Andromeda T' three rings on t' fin can act like exterior centerin' rings. Ya scallywag! Countin' these, shiver me timbers, me bucko, t' main fins are mortised with 7 centerin' rings. Ahoy! T' 3" tube goes all t' way t' t' bottom so thar is only 1/2" o' fin "through t' wall". I tried t' compensate by ID fillets & epoxy rivets. Avast! T' entire ID o' t' 4" tube is coated with epoxy and t' CR/fin joints have 1/4" o' epoxy poured on them, all sides. All epoxy betwixt t' 4" and 3" tubes are 2 hour slow cure. In all, the fins are attached with 9 oz o' 2 hour epoxy. Avast, me proud beauty! Another bit o' security was several (probably 30 or 40 in each fin) 1/4" deep 1/16" holes drilled into t' fin roots t' act as epoxy rivets.

T' small outboard fins are attached with four 2 1/2" long 1/8" diameter oak pins. Begad! Aye aye! Each pin goes through t' main fin and into each fin 1". Ya scallywag! 2 hour epoxy here too. Again, another bit o' security was several 1/8" deep 1/16 holes drilled into t' fin roots t' act as epoxy rivets. Begad! Arrr!

T' conduit dowels were secured t' t' main fins with a kind o' mortise and tennon thing. Begad! T' depth o' t' mortise is about 1 /1/2".

I just had t' throw this in for good measure: Nay countin' any internal fillets, me hearties, arrr, t' total length o' t' fillets on this puppy is 41.6 feet. Well, blow me down!

Finishing:
Scratch 4x Andromeda Finishin' t' rocket was one o' the more difficult tasks. Arrr! T' majority o' t' "decals" were made form Super Monokote. Avast, me proud beauty! Aye aye! Jim Z made some upscale "paint masks" for me. Ya scallywag! Avast, me proud beauty! At first, me bucko, shiver me timbers, I tried t' rubber cement/paint mask thing. Arrr! Avast! What a disaster! T' paint bled like a stuck pig. Blimey! So I 86'd t' paint mask idea and cut out t' decals with orange Monokote underneath. Begad! T' white be done t' same way but I used sticker material. Begad! T' paint was Rustoleum satin black. Begad!

T' three "coolin' rings" were painted white in t' '75 & '76 Estes catalogue. Avast, me proud beauty! Blimey! Ahoy! Blimey! They were painted black in t' '77 through '82 catalogues. Well, blow me down! Blimey! I opted t' paint them white t' add contrast in t' area. Ya scallywag! Blimey!

Flight:
Well, I sent t' Andromeda up on a J350. It left t' pad with authority and flew perfect. Well, blow me down! It arched over at apogee and t' deployment came out perfectly timed.

Recovery:
Wait... What's this? T' chute is tangled! T' darn thin' backward slid all the way in at a pretty good clip. Avast, me proud beauty! (That's what 16 pound rockets do ya know.) It hit the ground with a thud. Begad! Nay pretty. Well, shiver me timbers, blow me down! With me heart stopped, shiver me timbers, and me stomach in my throat, I told me self "its only a rocket, right?" I am in the process o' rebuildin' it right now and should have it ready t' fly again at the May 11 NEPRA launch. Avast!

Summary:
Wow! this was much more work then I had anticipated.

Other:
Upscalin' old Estes kits is a great way t' build HPR and remember your youth at the same time. Ya scallywag! Here is a video. Well, blow me down! Avast, ya bilge rat, me proud beauty! It's a bit big at 2.3 megabytes.

comment Post a Comment