Pratt Hobbies D-Region Tomahawk

Pratt Hobbies - D-Region Tomahawk

Contributed by Howard Bernstein

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar_border
Manufacturer: Pratt Hobbies
 

I purchased this kit because of the wide variety of motors it can handle (A-F, 18mm, 24mm and 29 mm), and because it had a streamer recovery.  I fly from smaller fields and want my rockets to come down rather straight.  The D-Region Tomahawk is a 7.2:1 scale model of a NASA sounding rocket (whatever that is). I like the way it looks.

[Rocket Pic]Construction

I thought the Tomahawk was fun to construct, especially the motor mount tubes. 29mm motors fit directly into the main body tube with some masking tape for a friction fit if necessary. Many of the motors Pratt has tested with have a built in thrust ring. The 24mm motor mount is built up out of five 3" body tubes. One tube remains whole, while the remaining four tubes are reduced in diameter by cutting 1/8" to 9/16" gaps along their length. The tubes are then glued one inside the other until you're left with a 29mm to 24mm adapter. A thrust ring is glued along the bottom, and the tube slides into and out of the main body tube with only a small amount of force. The 18mm mount is a standard tube, thrust ring inside, two 24mm rings outside. The 18mm mount is friction fit inside the 24mm mount, with some addition masking tape inside the front of the 24mm mount to keep the 18mm mount from moving forward. It probably sounds more complicated than it actually is.

[Rocket Pic]The fins are laser-cut plywood. They sanded to an airfoil shape rather easily. I felt the need for a wrap around fin alignment strip, as the flat, cross-hair over circle on the instruction sheet was rather hard to use. It took only a minute to make an accurate wrap around guide.

The model uses a Kevlar® shock-cord, so I reinforced many of the body tube ends with thin CA and later found myself sanding the interior of the tube to bring it back into the appropriate dimensions (no fault of the kit).

I got the impression from the instructions that the little clay nose weight (recommended if 29mm motors will be used) should be pliable and pushed into the nose cone with a pencil. However it was a little clay rock, so I glued it into the nose cone with some thick CA.

Rating: 4.5 points

[Rocket Pic]Flight

First flight was on a B6-4 motor. I was kind of chicken to fly it on an A8-3. Since this is the biggest, heaviest rocket I've built, I wanted to make sure it got enough altitude the first time out. The launch was really nice, and the recovery was what I would expect.  However, I forgot to friction fit the 24mm mount inside the main body tube, so it too was ejected (oops). Fortunately, we found the motor mount very near where the rocket came down, so we lived to fly again! Next flight was on a C6-5. This time the motor mount stayed in. This time the motor mount stayed in. I would have flown the Tomahawk again (and again and again), but it was starting to get dark and my typically under-dressed son was getting cold. I'm not a great judge of altitude, but the B motor took it up about 300-400 feet, and the C motor 500-700 feet, maybe higher. [Editors note: This kit comes stock with streamer recovery]

Rating: 5 points

Overall

I flew the Tomahawk only in its primer, so I didn't get the chance to use the solid color decals that come with the kit, though they look good.

I really enjoyed the building process. The parts were all of high quality. Minor nit was that not all the 3" tubes for the motor mount were the same length… one was different. I ended up swapping it with the coupler tube, which was the same size.

I am also really looking forward to flying this rocket through the entire range of motors from A to G.

I wish the motor mounts were a little easier to deal with…maybe a setup where masking tape isn't necessary for putting the 18mm into the 24mm.  On the other hand, I know of no other rocket as versatile as this one.

Overall Rating: 4.5 points


[NAR][Sport Rocketry]

The following excerpt is from "Sport Rocketry". The intention is to allow guests to get a basic feeling about a kit. We strongly suggest that you get a copy of the referenced Sport Rocketry and read the entire article. Inside you will find many helpful hints in construction as well as other useful information. For more information, use the two links above.



(Sport Rocketry - May/Jun 1999 - page 39 - by Greg Elder)

"The Pratt Hobbies D Region Tomahawk is a sport scale model of the real single stage NASA sounding rocket designed to travel to the D region of the ionosphere."
". . . one feature piqued my interest. Specifically, this model rocket can fly using any motor from an A8-3 up to a G35-7."
"It uses a very thick body tube, about three times the thickness of a similar Estes model . . ."
"The nose cone is vacuum formed plastic."
"In addition, the four fins for the rocket are laser cut from lite plywood."
"For the recovery system, a Nomex® cloth heatshield is included with the kit to use as permanent wadding to protect the plastic streamer."
"Construction of the D Region Tomahawk is very straightforward. The four pages of instructions are easy to follow."
"Pre-cut color trim tape is included with the kit to be placed around the nose section of the rocket."
"The kit includes parts to construct adaptors for 18mm and 24 mm motors."
"I chose to use a G35-7 motor for the first flight of my D Region Tomahawk, in order to see if it would really hold up to a G motor."
"At ignition, the Tomahawk quickly leapt off the pad for a very straight flight."
"When I recovered the rocket, I found that the nose cone section had broken [away] from the shock cord."
"Furthermore, the plastic streamer had melted slightly. A larger size piece of Nomex® would be better."
"I contacted Pratt Hobbies about the Kevlar® breaking on the first flight . . . The company . . . said they would now be using longer pieces . . . "
"Overall, I recommend the Pratt Hobbies D Region Tomahawk."

The entire article gives the impression is that this kit for a beginner/novice modeler.

Other Reviews
  • Pratt Hobbies D-Region Tomahawk By Howard Bernstein

    - by Mike Goss Introduction: The Pratt Hobbies D region Tomahawk is a sport scale model of the NASA sounding rocket. It gets it's name from the D-Region of the ionosphere, which is about 75 to 95 km above the earth. This rocket is still in use by NASA to send instrument payloads into that region for scientific study. The finished rocket is just over 26 inches tall and has the distinction ...

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