TOPIC: New User Starting with TSP L1 Motors

I am just getting into flying using the TSP motors, I do have a couple of old Jetex motors I have never used. First time out I attached the L1 motors to a couple of old HL gliders, Thermic B and Thermal Piglet. After a little adjustment the gliders flew fine but not very high. Next time out I used a tissue covered rubber model with 20" wingspan. This climbed higher and much better glide but I will try for better performance. I notice from thrust graph, it starts out pretty strong but tapers off quickly, rather like a rubber powered model.

Hi,
you don't say what span and weight the Thermic B and Piglet are. The TSP L-1 motors have a thrust of 100 mN which should give a small model under 15 grams a very sprightly performance. Could I make a suggestion and you make a model specifically designed for the L-1, a Jetex Wren for example ?

See:
Wren



There are others, of course, like the Lansen.

I hope this helps

Thank you for your suggestion, I just weighed the HL gliders and they were close to 40 grams! The rubber model was around 25 grams, which explains why it flew better. At 15 grams performance should be lively. I will try the design you suggested and also work on built-up structures. I would like to come up with something to fly in US Nats next summer that would glide well also. I noticed one design for Jetex 50 hand under camber.

I attached video of the glider flights.

Bill Kuhl

Roger adds:

Hi Bill, where is the video? It doesn't appear to be attached!

Hi Bill, it's good to hear from you.

I note your comments regarding the L1. I made a few plots a couple of years ago with a logging system I put together. Those tests seemed to indicate if anything a slight increase in power as the burn proceeded. (possibly as the tube and the mix warmed up.)
I must say I haven't had chance to repeat these tests recently but for what they are worth here is a plot.





Roger adds:
A problem with the thrust/time graphs is that the organisation that produced them are more used to measuring high thrust/short duration motors designed for ballistic-type rocket models. This can make interpretation for our purposes quite difficult. I would trust Terry's graphs more. My 'low-tech' set up too, was more geared to the 70-500 mN thrust motors useful for our very different sorts of models.

Here is my graph for the L-1 V2 when Piotr, Terry and I were fixing its performance:



Note I have not included the initial 'spike'.

The latest CE TSP motors I've tried match this quite closly.

I am looking at the graphs that were done on the Hummingbird Products website where I purchased my first batch of motors, It shows thrust peak of 1.95N but average only .10 N. To me that seems rather extreme. Someone told me to use some side thrust, what I saw was it turned more severe to start and then turn opened up. I reduced the side thrust to a very small amount and the circle was great after that. My videos are on the National Free Flight Society YouTube channel. The lighter plane did climb some the entire flight as I got the trim sorted out. Anyway it is really fun working with a different power source and trying to optimize airplanes around it.



Bill

Well the graphs that Hummingbird are posting should be considered definitive. As I say, I haven't had time to retest any motors in some time and I imagine that those graphs were derived from the test rig at Klima Modelbaue so I'm sure it's well calibrated.
www.raketenmodellbau-klima.de/

Roger adds: note above my reservations about Klima's graphs.