Hi Guys,
Andy Blackwell and I have tested the latest batch of L-1 and L-2 Rapiers. Our very own 'Nighthawk' in his secret mission to the Czech Republic saw Dr Zigmund and brought back a batch of L-1s labelled '70mN' and batches of three types of L-2 labelled, "120, 140 mN and 'unspecified'".
This is what we found:
Above: graphs for the latest L-1 motors. Very nice, but a bit more powerful than expectedd
Above: two of the '120' motors look very usable; the third will give a very exciting flight indeed. The '140' motors are even more powerful showed a peak which was off scale. The 'unspecified' motors gave a similar performance and should probably be labelled 'HP'.
These result were a little disappointing, but as these are static tests on my test rig we thought it best to try them out in models on the flying field so an accurate assesment of their performance 'in the real word' could be made.
This we were able to do at 'Mayfly' Old Warden (see separate thread) with the following results:
The L-1 overpowered my Lansen profile model (below) and sent it to the stratospere. Great and not unexpected, but trimming the Lansen for the extra thrust was a little nerve-racking!
My Super Sabre for L-1 is a little larger and heavier, but it also needed a some readjustments to the rudder and ailerons ( a dead straight glide is the one to aim for) before it gave a lflight which, compared with last years' L-1s, showed the pilot had engaged the reheat!
Conclusion: these motors ignited easily and can be used with care, but will work best in an 'L-2' size model. Also, I suppose, in an L-1 duration model!
The '120' L-2s have much more thrust than last years 'standard' L-2s. This is not a problem if you are prepared for the extra 'oomph' and reset the conrol surfaces or cg accordingly. The will definately overpower a small profile model like the T-38 if the trim tab is not turned down.
The '140's worked well in my large Skyray:
Above: my semi profile Skyay is quite large and heavy (40g with motor) and was designed for an L-2 HP.
As the graphs indicate, the thrust built up during the flight, giving a smooth climb out followed by a fast climbing turn to height until cut off. This was OK and better than the model did with an old HP, but duration was still a little disappointing. I think they will suit a model like the old KK Swift very well.
Above: Howard Metcalfe's Swift doing its stuff at Middle Wallop last year. This is a large model that needs a fair bit of grunt which the latest '140' motors will certainly provide.
The 'unspecified' motors gave, as far as I could tell in the variable conditions, a similar performance. As the graphs simply, a couple of the eight test flights with the '120' and '140' motors were distinctly 'wimpish', giving a cruise at a little over head height, which was just asking to be shot down in the turbulent air we experienced at Mayfly.
Conclusion: The latest L-2s ignited well and are usable with care. They are less predictable than last year's motors, but then, rocket flying is all about excitment and not for the faint-hearted. These motors will certainly give that, but the flyer will have to persist in retrimming to get a flight that doesn't end up smoking on the ground!
We hope Dr Z will be visiting in July with some more motors and we can discuss our findings with him.
So; onwards and upwards!