As part of the planned 'beta testing' phase of what is still a new product, I have retested the batches of TSP L-1 and L-2 motors we received from the estimable Piotr Tendera in September 2021.
This gave satisfactory and some interesting, if unexpected, results.
1. One surprise was that, in contrast to Rapier motors, the Tendera motors were reluctant to ignite with a 'standard' 'Cord Zap' igniter.
To light these motors, even with 'boring out' some of the propellant, the voltage needed at least 4.5V rather than the 3V or so given by two AA batteries. The 28 SWG element really needs to be glowing.. David lane's igniter (6v or so) worked well.
2. A bigger surprise, again in contrast to Rapier motors, was that TSP motors ignited reliably with just a short length of fuse, without the need for any boring out of propellant.
3.The performance of motors was entirely as expected from experiments conducted last year (below)
L-1 motors produced a little over 100 mN for 15 sec; As received, without any boring out of nozzle or propellant; September's 'TSP L-2 HP produced a powerful 300-350 mN for 16 sec; boring out the nozzle to 1.7 mm resulted in a very nice thrust of 150-170 mN for 19-21 sec.
I would add that I also tested some of the prototype TSP L-2 motors I received in the spring of last year. These gave a nice 150 mN for 25 sec. I would be happy to share these at meetings (if we have any this year!).
I was careful to test duplicates of each motor (and blow the expense!) and it has to be said that these results are more predictable and reliable than for my Rapier motors.
This is most encouraging - we can fly with the motors we now have in stock (both Terry and I have quite a lot) and we can pass these on with a clear conscience
What I'm less happy with is selling my modified 'Cord Zaps' unless I also include an adequate supply of fuses. I shall need to liaise with Piotr about fuses, and talk to David Lane about his much more potent igniter!