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Aim for the sky and try not to miss!
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IQSY Tomahawk
By: Michael Hoy

Michael Hoy of Florida presents us with a sport scale version of a very well known sounding rocket, the IQSY Tomahawk

Michael provided the following information with his entry:

Once again I'm entering your DOM. 2004 of course. Well maybe it won't get to you for a few months but it doesn't really matter. I notice you have ZERO scale models so far. This design is very kitable and very high performance going to about 1200' both in RockSim and observed on a C6-7.

If you want a cheap to produce scale model that is popular (good 'ol IQSY) and performs like a devil on small engines this is the one to start your scale FlisKits fleet with! I've flown the proto several times now and it takes off like a bullet and recovers fine on a streamer.

Michael W. Hoy

In a followup message, Michael provides the following:

IQSY Tomahawk BT- 50, 1 : 9.22 Semi-Scale Model

In order to simplify construction in my prototype model I used a readilly available plastic nose cone that is a close match to the original real nose cone. The only real difference is it has a 4.22 : 1 ratio whereas the actuall nose cone has a 5 : 1 ratio. Both are Ogive. In practicall terms it means I lengthend the body tube in my design by about roughly 3/4" to keep it all at scale length. If you have a 5 : 1 ogive nose cone you want to use then place it in the end of a length of BT-50 body tube and measure from the tip of the nose cone and make a mark at 21 5/16". This is the length you want the nose cone & body tube combination to measure no matter what nose cone you use. This is also the one of two reasons I'm calling the prototype a "semi-scale" model rather than a scale model. The other reason is the scale width of the fins should be 0.054", but I think thats to thin for balsa. If I had a 5 : 1 nose cone I'd call it a scale model anyway.

Changing the nose cone will not change anything else about the model regarding the paint plan or how far back to mount the fins. All those measurements are based on the model's body tube and nose cone combination being 21 5/16" long. It should not change the model's Center Of Pressure or Center Of Gravity to any noticable amount either. The total rocket length should be 21 1/2". The fins overhang by a scale 0.203" wich for simplicity I round to 3/16".

The lower motor mount centering ring is recessed 3/4" from the bottom of the body tube. This is done to accept a booster stage (Scorpion, but think Nike Tomahawk ) that I made for another model. For a production model it would be recessed only 1/16" for epoxy filleting, unless ofcourse you wanted to offer the two stage version or suck in buyers for a later booster stage Nike. :)

Total Length : 21 1/2"
Body Tube & Nose Cone Combined Length : 21 5/16"
Body Tube Length using but not with SureFire PNC-50 Type 2 NC: 17 3/16"
Body Tube Length using Balsa Machining Services 34" tube is reduced to 17", this allows two body tubes from one length reducing cost. BMS also sells the best quality white tubes. Using BMS tubes reduce scale accuracy slightly but increase quality.
Fin Overhang : 3/16"

***Some of this stuff I forgot all about untill I decided the IQSY would be a good entry. Whats most important to a scale freak like me is the IQSY flies high on just a B6-4 and goes way high on a C6-7. I thought about using a 12" 'chute but a streamer is the only real option since it goes over 1200'. Scale sounding rockets should perform like sounding rockets and this one does.

Michael W. Hoy
a.k.a. ZippyOgiveHead (TRF handle)

Michael also provided this history of the IQSY Tomahawk:

The original 9" diameter Tomahawk rocket was built by Thiokol for research use by the Atomic Energy Commision. 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

A Sandia Corp. sounding rocket. Could lift 20.4 kg (45 lb) to about 160 km (100 mi).

Developed by Sandia Corp. for nuclear weapons work. Could lift 45.4 kg (100 lb) to 322 km (200 mi). NASA has used the Nike-Tomahawk for research purposes since 1965.

Sounding rocket. Year: 1963. Family: Nike. Country: USA. Manufacturer: Sandia.
Two stage vehicle consisting of a Nike booster and Tomahawk upper stage. Payload 45 kg to 370 km or 115 kg to 215 km. Launches: 395. First Launch Date: 25 June 1963. Last Launch Date: 27 November 1995. Payload: 45 kg. Apogee: 370 km. Liftoff Thrust: 217.00 kN. Total Mass: 990 kg. Core Diameter: 0.42 m. Total Length: 10.80 m. Cruise Propulsion: Solid. Cruise engine: TE-416. Narrative: The sounding rocket was originally designed by the Sandia Corporation in support of Atomic Energy Commission programmes. It was subsequently adopted by NASA and Germany for scientific studies.

Sounding rocket. Year: 1983. Family: Honest John. Country: USA. Manufacturer: WFF.
3 stage vehicle consisting of 1 x Taurus + 1 x Nike + 1 x Tomahawk. Payload 32 kg to 700 km or 125 kg to 400 km. Launches: 17. First Launch Date: 01 September 1983. Last Launch Date: 06 December 1991. Apogee: 700 km. Liftoff Thrust: 457.00 kN. Total Mass: 2,200 kg. Core Diameter: 0.58 m. Total Length: 15.30 m.

The links below will provide you with instructions and patterns for this design.  These links will open a new window.

  • IQSY Tomahawk Documents
Fin pattern
Fin Plan
Fin Bolt Plate
Paint Plan


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