Proposal: L3 competition for airframe-free rockets.

[StreuB1]

Neat

 

[RGClark]

It seems to me that a fincan has a body tube that is affixed to / built with the fins and is shorter than the motor...

Does airframe-free mean that fins, engine, and nosecone must only be connected to each other by the structure of the engine?

You are basically turning your engine casing into your airframe then (assuming definition of airframe means the structure that connects nose cone to fins).

Maybe this actually means that engine combustibles are loaded directly into airframe so maybe this is a engine-casing-free competition (reloads go directly into airframe).

View attachment 546762

By airframe-free I mean no body tube covering the motor casing. The USCRPL team that made the Traveler IV rocket to reach suborbital space did not use a body tube, but integrated the fins into their carbon fiber casing for their motor.

The Project Mesos rocket that essentially reached suborbital space at ~90 km did not use airframes. The Princeton team that made an attempt to suborbital space but failed because the upper stage didn't light also didn't use airframes. Note the sims showed it would reach the 100 km line if the stage had lit.

I also did a sim of the FourCarbYen rocket showing without airframes it also could have reached the 100 km line:

Post in thread 'Unexpectedly high RASAero estimate for a two-stage rocket.'
https://www.rocketryforum.com/threa...te-for-a-two-stage-rocket.145740/post-1785088

These examples suggest for amateur teams to reach the 100 km von Karman line for space they’ll need to produce rockets without airframes. Quite interestingly, the sims show commercially available motors using combinations with O-class through M-class with staging can reach 100 km as long as they don’t use airframes. This is literally with using the standard off-the-shelf commercial motors at this size class with staging. No alterations to replace the aluminum casing with carbon fiber required. No altered nozzles for optimized vacuum performance required.

What it would require is experieince with high powered motors AND facility with ignition of upper stages at high altitude, not a trivial task even for experienced amateur rocketeers.

And to reach the next stage beyond suborbital space, producing airframe free rockets is even more so a necessity.

Bob Clark