Scratch - Alien Ship {Scratch}

Descon Alien Ship

Scratch - Alien Ship {Scratch}

Contributed by Bill Adams

Manufacturer:

Scratch

Alien Ship
(Contributed - by Bill Adams)

[Rocket Pic]

This rocket is designed to look like the one appearing briefly in the movie "The Stupids".

[Rocket Pic]

Flight Report

My prototype flew successfully at Battle Park '98 in Culpeper, VA on an Estes D12-5. It really got up there (1000'?) on a quick but easily followed boost, deployed the parachute near apogee and sailed a good bit, landing in the adjacent cornfield without damage.

Engines

D12-5 (tested), C6-3 (should be ok)

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Parts

Application     Qty  Description
=============================================
body             1  BT60 18"
cabin            1  BT50 12"
body nose        1  PNC60    (Tomcat style, 
                    4+3/4", current parts pack)
cabin nose/tail  1  PNC50KA  (2+3/4" long, current 
                    parts pack)
faux engines     2  BT50 2+5/8"
fins             1  basswood sheet 4"x3/32"x24"
wing pods        3  BT5 1+1/4"
wing pods        6  PNC5  (Quark style, current 
                    parts pack)
motor tube       1  BT50 3"
shock cord       1  48" long, 1/4" elastic
parachute        1  18" nylon
centering rings  2  CR5060
launch lug       1  3/16" diam

Building Instructions

Builder Preferences

For the prototype, I used plastic glue for the fin pod cones and cabin cones, yellow glue for attaching and filleting the cabin tube because it required hands-on holding and a quick set time, and epoxy for everything else for maximum strength and smooth joints. The cabin nose and tail cone sections were filleted with Elmer's Fill 'n' Finish for a smoother transition. I used a BT50 motor tube without retainer and an 18" nylon parachute. Everything worked great on its first flight, but can of course be changed according to the builder's preferences.

Engine Mount

Assemble the engine mount in the typical fashion (BT50 with CR5060 centering rings, and engine hook if desired), with the rear centering ring 1/2" from the end of the motor tube. Glue the motor mount into the rear of the BT60 body tube so that the rear centering ring is 1/8" inside the body tube. NOTE, if you want to install a motor mount anchored shock cord leader, do it now.

Cutting Fins

Print out the fin patterns and scale them to the correct size. Cut out the patterns, lay them on the basswood sheet with the orientation arrows in line with the wood grain, and trace them onto the wood. Be sure to make 1 tail trace and 2 wing traces. Cut out the fins and round the leading and trailing edges.

Fin Pods

Mark a single line (like a fin centerline) on each of the BT5 tubes for their full length. Trim the shoulder of each PNC5 cone to a length of 1/4" (do not attach the end caps). Glue one PNC5 nose cone into each end of each of the 3 BT5 tubes. Cut a 3/32" wide by 3/4" long slot centered on the line, running between the nose shoulders.

Test fit the fins into the slot in the pods and trim to fit. The fin shoulder should touch the pod, and the fin tab should extend through the BT5 and touch the opposite side.

After trimming, glue the pod to the end of each fin and fillet.

Fin Attachment

Mark the body tube in the standard 3-fin pattern. Extend the fin lines from the rear of the tube to the middle for the wings, and for the entire length of the tube for the tail. Attach the fins flush with the rear of the body tube one at a time, allowing each to dry before proceeding with the next. Fillet all fins one at a time.

Cabin

Use a 4-fin alignment guide and make 3 of the 4 marks. Extend all three marks for the length of the tube. The center mark of the three will be cut as a slot to allow the tail fin to protrude through it. Mark the slot 3/32" wide, centered on the mark and extending forward from the rear of the cabin tube for 5+1/4" inches. Cut out the slot, then cut the cabin tube in half LENGTHWISE along the remaining two lines (the unslotted half will not be used). Test fit the cabin tube on the body tube, with the tail fin going through the slot, and trim as necessary. Be aware that the tube will twist because of the heavy cutting and appear to bind just due to the twisting, so do not trim too much in trying to get it to fit easily.

Holding the cabin tube in place, mark the body tube and the tail fin along the contact area. Remove the cabin tube, apply a thin coat of yellow glue along the contact lines just drawn, and reinstall the cabin tube and hold until dry to overcome the tube's twisting. Once dry, fillet the cabin tube joints to fill any imperfections and to be sure it doesn't pop off.

Cut the PNC50KA nose cone in half lengthwise (use the mold seam as a guide). Cut one of the halves lengthwise again (into quarters). Test fit the half cone in the leading end of the cabin tube and trim to fit (this will take several passes). Similarly trim the quarter cones to fit into the rear of the cabin tube, one on either side of the tail fin.

Glue the cone segments to the cabin tube and body tube. Smooth with putty/etc. as desired.

Faux Engines/Lug

Glue the faux engine tubes against the wing fin and body tube, 1" from the rear of the body tube. Glue the launch lug to the INSIDE of one of the faux engine tubes, against the body tube.

Recovery

Install your favorite shock mount, cord, and recovery system. I used an Estes style folded paper mount covered with epoxy, a 48" length of 1/4" wide elastic, and an 18" nylon parachute.

Painting

White: body, cabin, wing pods
Light blue: wings, tail, tail pod, faux engines
Dark blue: wing leading edges (1/4"), tail stripe (3/8"), tail lettering (1/4")
Black: motor tube, faux engine stripe (5/8"), window details

About the Designer

I'm 27, a several time BAR. I began in 1975-ish, with a heavy building spree in the early 80's (Estes kits). I briefly revisited the hobby in 1991 and 1994 to repair the fleet and fly a few rockets. I finally resumed new construction (mostly up/down scales) in 1997. This is my third original design.

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