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!
You will see from Terry's recent blog that the TSP motors have achieved the long saught-after CE certification, and that Piotr has some nicely packaged examples:
Piotr has provided the following specs:
These look to be a very nice product indeed (note the inclusion of fuses) and Terry and I hope to test some examples and publish the thrust/time graphs soon.
Certification is of course only the first step to legitimate retailing of motors, and we do not know how long this process will take.
But (and this is good news) we have adequate supplies of what could be called -1 'precertification' motors. These are now tested, and bagged or boxed up and available from me, so please contact me for prices and availability.
These are reliable motors and should last us at least until supplies of the new certified motors are available.
The L-1 motors are all rated at 88-96mN for 17 sec; the 'L-2' motors are more diverse, with thrusts ranging from 180mN to (gulp!) 420mn. Thrusts can of course be tuned by boring out nozzles to suit the model. We have a few L-3 motors of higher thrust too.
I'm tempted to say, "Hurry, hurry whilst stocks last".