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Originally Posted by Ez2cDave
A couple of pics . . . Good "rivet detail" in the first one !
Dave F.
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Another commonly-used (but not documented, to my knowledge) Australian sounding rocket was the HAT (High Altitude Temperature). It used the same three-finned LAPSTAR second stage (LAP stood for "Light Alloy Plastic" [PVC-based plastic propellant, in a light alloy motor case]) as the HAD (High Altitude Density) sounding rocket, a photograph of which is the first on the left, in posting #1 of this thread, but:
Instead of the single Gosling first stage motor of the HAD, the HAT used two smaller, side-by-side Demon rocket motors as its first stage (much as the Aeolus used a Long Tom second stage [a Mayfly motor] atop a less powerful cluster of seven LAPSTAR motors, all mounted inside a short enclosing tubular airframe with a short conical interstage adapter and four rectangular fins), and:
The HAT's first stage had four rather long-span clipped delta fins (two on each Demon motor), and because of their side-by-side attachment (with a rather "flat" [matching the motors' diameter in depth, and twice their combined diameters in width] conical interstage adapter on the front end), the fins formed a sideways "X" when viewed from the top or bottom. A home-made "two-to-one" ducting (and vented) gap-staging adapter (like the "one-to-three" ducting staging manifold adapter that John Boren developed for Estes' MIRV kit:
https://estesrockets.com/wp-content...002134_MIRV.pdf ) would enable a HAT scale model to ignite its second stage with the hot particles from ^both^ booster motors. Also:
This would--if the model was light enough to climb sufficiently high and not arc over too much, if one of the two first stage motors failed to ignite at launch--offer greater overall reliability. If both first stage motors ignited, second stage ignition would be almost 100% certain to occur, and if only one first stage motor ignited, second stage ignition would still be nearly as assured as it would be in the first case. *OR*, one of the two first stage Demon motor tubes could be vented to ignite the second stage, while the other one could have a rear-ejecting motor mount on a shock cord, to enable parachute of streamer recovery of the first stage (it would use a short-delay motor of the same total impulse category as the "dash-zero" booster motor in the other first stage Demon motor tube, such as a B6-2 and a B6-0).