Spyglass 1



Spyglass 1 is a Rocket Glider.

That's not quite the same as a Boost Glider; a Boost Glider may eject parts of the model in order to change flight regimes from boost to glide, and as long as the ejected parts are recovered safely by streamer or parachute, you're good to go.  A Rocket Glider must not eject any part of the rocket, including the motor casing, while making the transition from a vertically launched, arrow-stable rocket to a lift-supported, airplane-stable glider.

The common ways to make a Rocket Glider transition are to slide a forward motor pod to the rear after a string is burned through by the ejection charge (thus being similar to a front-engine Boost glider but with the CG shift accomplished by sliding, rather than ejecting, the motor case), by swinging the wing from a trailed position into conventional flight configuration, or by sliding the wing from a position near the aft end of the model to one atop the CG, again actuacted by ejection charge burning a string.

Spyglass 1 is different from all of the above.

Spyglass 1 is a rear-motor configuration, uses no rubber bands or strings, and is actuated only by the force of the motor's ejection charge.  It boosts in a rocket-stable configuration, with wings and stabilizers close together, then on deployment comes to strongly resemble a conventional hand-launch glider with a tubular fuselage.  It uses a polyhedral low wing mounted on a short pylon, and a V-tail, with about 2 degrees incidence augmented by an inverted airfoil on the stabilizers.  The close-coupled boost configuration should prevent looping during boost, while avoiding the necessity of changing any surface angles or adjusting any flaps or hinged sections; this is potentially more reliable than those actions.

Spyglass 1 is complex: unlike an Alpha, with 11 parts including the parachute and shock cord, Spyglass 1 has 22 parts.  By rocket glider standards, this is on the low side, but it's the most complex model I've built to date and far more complex than any other rocket I've designed.  I'm looking forward to working out any bugs in the design and trying to get the most out of this concept.Spyglass 1

Flight testing in April 1998 indicated that, after the glide was sorted, the boost was fine.  The glider has shown capability of durations around 30 seconds in dead air -- this is comparable to an Edmonds Aerospace Deltie, but without shedding a boost pod -- and isn't perfectly adjusted yet.  I may have to build another, though; this one is starting to suffer from kinking of the tube around the forward vent holes due to a few hard landings in tests and when deployment failed due to powder fouling in the tubes.

To the right or below, you'll see a reduced plan view of Spyglass 1; click on the plan view to download a ZIP file (141k) of the complete plans and building instructions.  It's a non-trivial project -- an experienced builder probably can't finish it in a single weekend -- but, IMO, worth the time.
 



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