FLEET

 

Astrobee 500

In 2018, I was complaining about my lack of time to attend launches and dislike of painting with William Wallby. (When I moved shops, I lost my paint booth, which made the latter worse.) He suggested we do a join project where I do the building and he did the painting and flying and he suggested the Astrobee 500 as an interesting subject.

 

The Pictures

 

The Design

The first question with a scale model is always the scale. Since it's easiest to base it around available body tubes, we decided that 25% scale gave a good overall size of 76" (1.94m) and second and third stages that matched 5" and 54mm airframe tubing. The first stage didn't match well, but making it slightly oversized using a 3.9" coupler tube would still give the right feel.

  Prototype (in) Model (in)
1st stage ϴ 15.0 3.75
1st stage len 62.0 15.50
1st stage span 72.0 18.00
2nd stage ϴ 20.3 5.08
2nd stage len 76.4 19.10
2nd stage span 52.0 13.00
3rd stage ϴ 6.5 1.63
3rd stage len 167.5 41.88
overall len 306.0 76.50

The third stage had an aft cone (no fins). The first stage body is substantially shorter because the aft end is a large nozzle. Here's the usual overall drawing.

This rocket is pretty large, but has both little space for motors and little recovery space. Because of the nozzle, only a 38mm MMT works in the booster. While a 3" MMT might fit into to the second stage, there is more selection in the appropriate length in 54mm motors (plus this accomodates an electronics bay alongside the MMT). Of course the third stage is a 38mm minimum-diameter.

 

Construction

 

Historical Info.

From Rockets of the World, 3rd edition (page 191):

In the early 1950's, Aerojet General was America's premier builder of sounding rockets, producing the famous Aerobee line of liquid-fueled sounding rockets. But in the mid-50s, solid-fueled rockets, such as the Nike-Deacon and Nike-Cajun became attractive, economical competitors. In 1958, Aerojoet entered the solid rocket field with its Astrobee 75, but with limited success. In 1959, Aerojet tried again, introducing the first members of a new line of solid propellant rockets: the Astrobees. The first of these to be tested was the Astrobee 500.

The Astrobee 500, deployed for the Air Force Cambridge Research Laboratory (AFCRL), was a 3-stage rocket capable of carrying a 15lb (7kg) payload to an altitude 765 miles (1,224 km), or a 40lb (18kg) payload 600 miles (960 km).

The Astrobee 500 was launched from a rail launcher under the power of a high-thrust MB-1 booster. Its 2-second burn was followed by a 12-second coast, as the upper two stages cleared the densest layers of the atmosphere. Then the second stage ignited for its 30-second burn. The third stage was an Asp sounding rocket, its fins replaced by a stabilizing cone at the rear. Aerojet offered an option for attitude control to precisely orient the payload as it collected data.

The AFCRL ordered two Astrobee 500's, and on March 22, 1960, one was launched from the Air Proving Ground Center in Florida. The vehicle was to release "poppy" flares at altitude. These would act as beacons for geodetic triangulations by ground observers. But an unspecified failure of the launch vehicle ruined the experiment.

There is no record of a second attempt, but the end of the Astrobee 500 signalled the beginning of a whole series of Astrobee rockets. By the next year the Astrobee 200 and Astrobee 1500 were flying.