Estes Flying Model Rocket Kit Boxed Pro Doorknob  EST 9720

Estes Flying Model Rocket Kit Boxed Pro Doorknob EST 9720

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EST 9720
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Estes Flying Model Rocket Kit Pro Doorknob  EST 9720

Pro Series II™ Builder Kit
Almost 27 inches tall and powered by E and F engines, this 1:12 Scale Model is an impressive Sport and Scale model of the sounding rocket manufactured from Lacrosse rocket motors for the project Hardtack Nuclear Test Series.

During the mid-1950’s, the public concerns over nuclear fallout due to US and Russian testing was reaching a fevered pitch. To that end, President Eisenhower announced to the US on August 22, 1958, the US would ban further nuclear testing on or before October 31 of the same year. US scientists, wanting to gather as much data as possible, responded with Hardtack Series of tests. Scientists where interested in many scientific areas, but primary interest lay in the effects of radioactivity from underwater and above ground detonation.

The Hardtack Nuclear Testing Program consisted of 35 detonations in the Pacific Proving Grounds during the period of April-August 1958. Scientists, at the time, were chiefly concerned about damage to the ozone layer and possible effects of long-range radioactive fallout and determined that scientific measurements of the earth’s upper atmosphere (aeronomy) would help clarify what, if any, damage had occurred.

Single and two stage Doorknob rockets were developed using Lacrosse and Thiokol solid propellent motors and could launch an instrument laden sounding rocket to approximately 50 miles in altitude and capture radioactive data for analysis. Early results of this upper atmosphere data suggested little to no damage to the ozone layer was measured during the nuclear testing and water detonations probably produced enough ozone to replace what little might have been lost due to above ground testing. The Estes 1:12 scale model Doorknob is big and impressive. Simple to build and fun to fly, this kit will be big hit in both the sport and scale rocket categories.

The Estes 1:12 scale and sport model is big and impressive. Simple to build and fun to fly, this kit has two sets of decals available for those who want to turn this scale model into a sports model.

Skill Level Pro

18"(45.7cm) Nylon Parachute Recovery

Plastic Nose Cone

Slotted Body Tube

Laser Cut Fiber Centering Rings

Laser Cut Wood Fins

Screw on Motor Retainer

Water Slide Decals and Chrome Self Adhesive Stickers

1/4" Launch Lugs

Length 26.9"(68.3cm)

Diameter 3"(76mm)

Estimated Weight 10oz(283.5g)

Estimated Assembly Time 3-4 Hours (painting and glue drying time not included)  Download Instructions

Recommended Engines
F15-4, F15-6, E16-4, D12-3 w/Engine Adapter (sold separately)

Projected Max Altitude 1100'(335m)


Model Rocket Kits are rated by Skill Level

1 Beginner

2 Intermediate

3 Advanced

4 Expert

5 Master

Pro Mid to High Power Experiance

If you are just starting in the hobby start at the beginner level and move up from there at your own pace.

What is needed to build and fly

All model rockets come in kit form that require assembly.  The materials are primarily cardboard tubes, balsa or plastic fins and nose cone.  Materials will vary by model and are typically specified in the description of each kit. 

Additional supplies will be necessary to build and finish your model rocket kit and may include:

Scissors, Hobby Knife


Wood Glue, Model Cement or CA(Super Glue)


Masking Tape

Finishing Supplies like:

Wood Filler



Launching Equipment and Supplies like:

Recovery wadding

Launch Pad

Launch Controller

Power supply

Model Rocket Motors and Igniters

A safe place to fly using guidelines from the National Association of Rocketry Safety Code


Full one year warranty through manufacturer