John Wh

Hello, I've just seen this post. I have a Laser 45 and a Laser 50 that I've been renovating. I changed the bearings on the 45 and tried to bench test it but it wouldn't go, maybe need to grind the valves a bit. Can't remember where I'd got to with the 50; I think the exhaust valve needs some valve grinding too. I made a bit of a hobby of buying old gunked-up Lasers and renovating them, before selling them on. (Even though I only fly electric?!?) David, are you still interested if they need some more work?

Get neck ache when I visit there.

The old, pre-digital solution would be to use a logarithmic potentiometer, sound pressure-to-volume is a logarithmic relationship, if I'm remembering correctly. Is your current rotary switch a linear pot. ?

Thanks Paul. The servos I tested were each drawing 2Amps when taken to their maximum of 10kg.cm torque loading. The temperature never got above 60°C on the outside of the case (measured using a IR temperature meter). I always test servos now before putting them in my aircraft. You can get cheap servo testers which will constantly cycle a servo through its full movement . Every servo I get is run for 20mins or so with some loading on it to check it's not going to burn out. If we're prepared to buy cheapo equipment nowadays (I am!) then I think perhaps we have to take responsibility for testing everything ourselves. Futaba would be concerned if one of their's burned out, can't imagine the clone companies caring so much... Edited By Whisperit on 27/10/2016 19:21:57

The servos I tested came from an Amazon seller called Proster, or Proser or Prozer (it's actually very easy to change your selling name on Amazon, I think they've been 'developing' theirs!). A lot of the similar looking things sold on Amazon are actually the same and from the same factory (in China somewhere), but distributors buy their own Barcode numbers and print theitr name somewhere on it and try to pretend its unique. So, from your comments and a bit more research, mine are very likely clones. Perhaps Towerpro didn't trademark the MG996R name, or perhaps the clone distributors are trying to get away with it. Looks like Towerpro's have Aluminium shafts now. [by "vertical play" I meant the play in the vertical servo horn shaft expressed as the angle of up/down movement this causes in the servo horn. How much movement this causes in your connected push-rod/snake depends on how long your servo horn is.] Never actually tested a servo before, trying to think of what else to do.

The other function of the webs is to prevent the top and bottom spars trying to 'slide over each other' as the wing bends. (The webs resist the shearing forces between to top and bottom of the wing.) They make a big difference to how much the wing will bend up in flight. (Imagine an I-beam without the vertical piece joining the top and bottom parts together.) The actual stress direction on these webs, for both resisting wing bending and wing twist, is 45° to the spars. So, for maximum strength you should actually align the grain of the balsa at 45°, rather than horizontal or vertical - but it won't actually make much difference. (This is why you sometimes see steel I-beams with criss-cross struts instead of a solid web - making the beam lighter overall with the same strength.) By far though, the main advantage of webbing is to complete the front wing-box; combined with the top and bottom sheeting on the front quarter of the wing the torsional stiffness increases by several hundred times (do the maths, and in a theoretical case, it's actually 1000 times stiffer in resisting twisting forces). John

Torque testing ! :

Torque test: I built a test rig with a heavy weight hanging from the end of a 4cm servo horn. As the servo turns the torque builds up and the mass and angle at which it can't turn any more tells us the maximum torque. After several tests with 3 of these servos the maximum torque is 10kg.cm @ 6.6V (high discharge battery - no voltage drop so this is the servo limit and not the battery. Speed Test: This is very hard to accurately measure, so I just tested it against a Futaba S3003 servo. These MG996R servos are slightly slower in a 'race' test between maximum deflections. Freeplay: Rotation free play is approx. 0.7° Vertical play on servo horn is 1.4° - this is VERY BAD for a servo. Would not use this for an elevator. Resolution: The resolution is not good enough to move for each click of the trim on my transmitter. In general, it only moved every two clicks, but it did move by two click amounts, so it the electronics are registering the new position angle but mechanics can't respond so precisely. BUT, this is as good as the new Futaba S3003 I compared it to.