Friday, August 15, 2014

A new approach to finless (updated)

A few days ago, one Dean Black posted a unique finless design on Facebook (members can join the NAR group and look for Dean's name). He describes the design as "induction stabilized." He also has a .pdf describing the rocket (again, you'd have to join and ask for it). There are several criteria which must be met for this to have any chance of working. Thus, I will generally describe the rocket but will not provide details until I've flown one and can personally vouch for it.

His design is a two piece body with a central gap and no fins. The motor is in the top section. He claims * two things about this design. First, the rocket will be stable as long as the motor is burning, even if it is a slow speed launch. In fact, he says it is stable with no launch rod. Second, if the lower body is shiny (i.e. made out of aluminum), it will promote the after burning of the CO in the exhaust of a a BP motor. This creates a large, more impressive exhaust plume.

Update: * He sent me a video showing his finless, induction stabilized rocket flying from a flat platform with no rod. So, I guess this is more than a 'claim'.

I am now thinking of using hand rolled 2.5" ID tubing with a 29mm mount. I will have a recovery system (his are very light and don't have one) and will use a lug (just not to press my luck any further). Why the odd tubing? Well, I want to see that afterburn and, apparently, that won't work of the inner surface is crudded up with residue. So, I will cut up soda cans and shoot for a replaceable liner.

My plans may change up to and including their cancellation.

Here's a RockSim model I built just to get a feel for the CG.

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