ASP (Atmospheric Sounding Projectile) full-scale rocket

The ASP sounding rocket just might make a good first group project for UROC. A full-scale ASP is 6.5" diameter, 12' 9" tall (which varied, depending on payload). It was a sounding rocket made by Cooper Development and used in the late 50s during nuclear testing to fly through nuclear clouds taking readings. It was also mated with Nike boosters (known as ASPAN, for ASP and Nike) to fly, among other things, a mission to take solar measurements during a 1958 total solar eclipse. Six were launched from a ship off the Danger Islands in the South Pacific (of eight ready--igniter problems delayed one launch which eventually failed during second-stage burn, and postponed another until the next day--we could emulate that!).

Here are some ASP links:

Full scale:
length 3.89m = 12' 9"
finspan 51cm = 20"
diam 16.5cm = 6.5"
Nose cone (conical configuration) 34"

These sometimes flew with flares behind the fin tips for visual tracking, and that might be a fun thing to add, assuming we don't start any fires when it lands. They are 1" diameter x 8" long. Dave Urbanek suggested using Estes D12-0 motors, backwards, to make lots of smoke but negligible thrust.

My Rocksim file uses airframe tubes made from 6" Sono-tube, overlaid with a 6 oz and a 4 oz layer of fiberglass and epoxy, vacuumed. Using peel-ply release fabric and breather over the wet resin, then vacuum-bagging the assembly, you can get near the optimum resin/glass ratio of around 50-50 (by weight). I measured and weighed the tubes before and after glassing, and added the overlay as a separate piece in the Rocksim design. Half-inch thick fins were made by laminating 1/8" baltic birch plywood over 1/4" foam poster board, with solid wood edges.

For more details of the build, see the Construction Notes page.

It will need about a ten or twelve foot parachute and altimeter(s). This would add some cost also, unless we could find a surplus source or borrow things.

Try clicking these links (right-click, then Save Link As) to download the Rocksim (v. 8) files:

The ejection charge sizes were determined as follows: first by calculation, taking the volumes and multiplying by a scaling factor. The drogue (lower) bay is 16" long with an I.D. of 6" giving a volume of 450 cubic inches. Multiplying by .0076 g BP/in3 gives a recommended amount of 3.4 grams of FFFF black powder. (The usual way to calculate this is Length * Diam * Diam * .006.) The main chute (upper) bay is 20" long so it should take 4.3 g BP. The Recovery System Calculator (available online) recommended 4.5 g for the upper bay with ten #4 shear pins. I put in eight 4-40 x 3/4 nylon screws for shear pins. The length doesn't seem necessary until it comes time to remove the sheared pins after the flight--you need enought sticking into the interior to grab when removing them. The second phase involved actual ground testing, blowing the rocket apart sideways on the front lawn. This sure gets the neighbors' attention, and even caused a few passing motorists to interrupt their cell phone conversations briefly. Now I know that each of the bays should get five grams. The ASP was fitted with fully redundant altimeters and charges.

The Recovery System Calculator was run to determine chute sizes also, and a single 12' chute or two 8' chutes (elliptical or hemispheric) should give a reasonable descent rate. Landing on the Bonneville Salt Flats is rough, so a slower descent would be good for Hellfire launches.

The ASP flew at Hellfire 12 on July 16, 2006 on a Hypertek L hybrid motor, and was successfully recovered. See details.