009720 – Pro Series II™ Doorknob

(1 customer review)


Pro Series II™ Builder Kit
Almost 27 inches tall and powered by D, E and F engines, this 1:5.3 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.

Estesrockets.com will be out of stock of E16-4, F15-4 & F15-6 until the Fall.

Check with your local retailer for availability or use a D12-3 engine with adapter.

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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 1:5.3 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. This kit has two sets of decals available for those who want to turn this scale model into a sports model.

WHAT YOU NEED TO BUILD: Scissors, pencil, ruler, fine sandpaper, epoxy, carpenter’s glue, sanding block, hobby knife, masking tape, primer (white), paint (black, day glow orange, white) and clear coat (optional). Tools, construction and finishing supplies not included.

WHAT YOU NEED TO LAUNCH (sold separately): Porta-Pad E Launch Pad and Pro Series II Launch Controller, Estes model rocket engines, starters and recovery wadding. Six C 1.5V high quality AA alkaline batteries are also required for launch controller (not included).

Additional information

Projected Max Altitude

1100 ft. (335 m)

Recovery System

18 in. (45.7 cm) Nylon Parachute


26.9 in. (68.3 cm)


3 in. (76 mm)

Estimated Weight

10 oz. (283.5 g)

Estimated Assembly Time

3-4 Hours (painting and glue drying time not included)

Age Recommendation

Estes model rocketry is recommended for boys and girls ages 10+ with adult supervision for those under 12, and rocketeers of all ages.

1 review for 009720 – Pro Series II™ Doorknob

  1. Thomas L. Stump (verified owner)

    This is a very nice looking model when finished with the standard scale markings. It has thru the wall mounting fins, and a nylon parachute. I sent for the bonus alternate decal sheet (thanks Estes!), but opted to build it with the stock scale decor– much more attractive! This Doorknob kit is kind of a cross between a old Leviathan PSII and a Big Daddy, both of which I also have in my fleet. IMHO, I’d rather see it less like the Big Daddy and more like the Leviathan, with plywood fins and centering rings, and the elastic PSII shock cord of a Leviathan. I’ll make those modifications in my Doorknob, and I’ll feel more comfortable about launching with an E30, F26 or even F50. I’m also thinking about how I can modify it to fly as a Doorknob 2–could be a challenge! Hmmm–maybe an F15-0 to an E12-8? Or electronic staging????

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