2/3rd Scale IQSY Tomahawk

2/3rd Scale IQSY Tomahawk (6" dia., 11ft tall)

by John DeMar, NAR #52094

Scale plans:

Click on image for 11x17 plans (by G. Harry Stine)

Other resources:
Rockets of the World, by Peter Alway

History
    The original 9" diameter Tomahawk rocket was built by Thiokol for research use by the Atomic Energy Commission. Four single-stage rounds were tested from 1963 to 1964 with the goal of qualifying the vehicle for upper atmosphere research during the International Quiet Sun Year (1964-1965), a time of minimum solar activity. The 266 kg rocket could lift about 20 kg to an altitude of 100 km (near the edge of space).
    The first three rounds were failures, but the last flight, from NASA's Wallops Island, VA facility, was a success on Sept. 25, 1964. The vehicle apparently did not become operational for IQSY research as a single stage rocket, but the Tomahawk was widely used as an upper stage with a Nike booster.
   Thrust: 49,000 N for 9.5 seconds (an "S49000" in NAR terms!).

Current Status:

07/2007: Actually finishing the rocket!

New mmt tube, additional airframe tube, centering rings from Giant Leap.

More shockcord and a D-bag from QuickBurst. Kevlar strap from CLE.
04/17/03: New cone, shockcord, and AMW K570 ordered.
11/18/02: Considering changing the nosecone to the Performance Rocketry 5:1 ogive fiberglass cone instead of the non-scale PML 4:1 fiberglass cone. This would remove the body tube extension added to the base of the PML cone.
07/04/02: All components cut and test fitted. Fins are 'glassed.

Flight Plans:
3" dia. AMW M1350WW motor for NAR L3 Certification.

Fin Construction

(click on images for larger view)


Fin core is 1/16" G10. Fin size is about 16.75"x10.7". The goal is to have scale thickness and tapered leading edge.	Frame is 1/8" basswood. Epoxied to fin core & trimmed. This adds strength but is lighter than solid 1/4"+ G10.	Inside is 3/16" balsa, sanded to thickness of frame. Leading edge is also 3/16" balsa (not shown).	Each side is covered with 5oz satin weave fiberglass. Note the strip of ply added in the middle of the balsa as a sanding reference height. Each complete fin weighs 12 oz.

Motor Mount Construction


Custom G10 centering rings were cut using a PC board milling machine. Two 1/16" G10 rings (with fin alignment notches), one aft ring (copperclad), and one forward ring (with slots for shockcord anchor straps).	Fin canister assembly - test fit. A LOC 3" tube was used temporarily to show location. A phenolic 3" will be used. An additional CR was added at the leading edge of the fins.	Shown with first built-up fin (3 to go!). A slotted 6" PML coupler will make a rear-ejection fin can.	Another look. Note the Estes 'C' motor for size comparison. Estimated weight of motor mount and fin assembly: 5 pounds.
AIRFRAME CUTTING
Tube marker/cutter I made from a couple pieces of shelving material.	A razor or hacksaw blade screws into the end to mark. A clamp holds an L-shaped end plate to hold the measured position.	A closer look with a piece of angle aluminum to mark the fin slots. Masking tape protected the tubing from chipping while I cut it with a sabre saw.
Here's a test fit before gluing the fin can together. Four feet too tall for my living room!	Recovery System The design has a rear-ejected drogue parachute (separates just above the fins) and the main parachute in the upper section (separates at the scale payload break point). All shock cord anchors are 1/2" tubular Kevlar(tm) (no metallic hardware). Each anchor point has two independent straps. Shock cord is 1/2" tubular nylon.	Recovery Electronics At the mid-point of the rocket is the electronics bay to hold the RDAS altimeter for primary deployment events. A Pefectflite MAWD will back up the RDAS. Electronics mount inside a removable 3" coupler inside the 6" electronics bay. This allows the shock cord mount straps to pass through as a continuous piece.

At NYPOWER 2002

updated 07/16/2007, John DeMar