![]() Incidentally, in 1979, a few years after I switched from making RC equipment to making joystick controls for industry and electric wheelchairs, early failure of potentiometers in frequent use became a very real problem for which even major manufacturers had no solution - or at least not at a remotely acceptable price. Not an option for me, because (a) mine do not work consistently in any case (b) I no longer have any confidence whatever in them and (c) the bad design irritates me. If all you want to do is fly, not be bothered by the technicalities and it works, fine. That is my opinion of using an amp to do what 50mA could do with a perfect mechanis, and 100mA should be able to do with a reasonable one. In the early days of the car starter motor - long before the pre-engaged starters we now know - a Frenchman commented "It's brutal, but it works". Regardless of whether your own units work to your satisfaction - mine certainly do not, even on the bench, does anyone here disagree with my assessment of the design? And if so, how? It is because the leadsrew is - inevitably so inefficient that such high currents have to be drawn, with knock-on effects of larger and heavier batteries, voltage drops on battery terminals and in connecting leads and - worst of all - signal drop-outs if the retracts run off the Rx battery, or stalled or spuriously cycling retracts if the current trips come in. (these figures are slightly different from those I put elsewhere, but this is only about estimates and orders of magnitude) That these retracts always struggle and often fail to achieve that lift despite (data sheet, not measurement) taking up to 1 amp, suggests an overall efficiency of about 5%, or assuming a motor efficiency of say 50%, a lead screw efficiency of about 10% - which is precisely the sort of efficiency that (plain thread) lead screws are notorious for achieving, because most of the energy and torque is absorbed trying to revolve the threads, when the end load due to the leverage of at least12 to 1 is about 3 lbs. To do that in power terms 0.16 ft lbs per second, equating to 1/3,350 bhpĬonverting into Watts at 746 Watts = 1 bhp, that's 746/3.350 = 0.22 watts or, at 4.8 volts about 50 mA. ![]() The energy necessary to lift my two 4.4 ounce wheels 7 inches is 0.32 ft lbs, in in powpo. ![]() All sorts of products work to an extent despite poor design, I prefer to use products which are reliable because of good design.Īpart from poor fit of legs into trunnions, axles on legs and collets on axles and that engineering no-no, 2 locking screws in line, forming a pivot, all of which make it that much more likely that they will work loose under vibration (unless soldered, which I invariably do), apart from nonsensical lead lengths too short to reach the centre of the wing and impossible to join within the wing, apart from the plain fact that my two units extend only 3 times out of 4 attempts, but trigger into down/up cycles for no apparent reason, have distinct hesitation or tight spots perhaps due to thread quality, apart from reports on this web site and others of limit switches and motor leads failing under vibration, the single most glaring design error, that in my view after spending my working life involved in electro-mechanical design and production, should never have made it beyond a back of the envelope sketch, is the use of a lead screw, with no normal gears as such. I do not know whether Flyntruk or Kahlog have had time to read my postings on but I would be interested to hear from anyone who disagrees with my assessment of the design and quality of these units.
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