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Simon Clark

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Simon Clark last won the day on October 6 2022

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  1. I've tried loads of different types and these Fastrax units are by far the best: https://wheelspinmodels.co.uk/i/125300/ I've never owned a Laser so cannot be certain that it will fit but can't see why not. Simon
  2. All servos and pushrods / control surfaces act as a closed loop control circuit and any control system can go unstable under certain circumstances if the gains are too high and there is not enough damping. This is a slightly simplistic way of looking at it and the reality and associated maths is very complicated. It is possible that the mass of your rudder coupled with the mechanical throws that you have are hitting a resonance point and causing control instability. By gently touching the pushrod, you are introducing a small amount of damping which takes it away from the unstable point. Some servos will suffer more than others and with tolerances even two examples of nominally the same type may react very differently. It is safest just to swap the servo out for a different and better type but you could try changing the mechanics of your system a little by moving the pushrod onto a different hole on the control horn or servo arm - yes this will change the overall rates but to a certain extent you can compensate by using servo end point adjustment and rates etc. Good luck Simon
  3. Hi, 8BA is just a little larger than 2mm but might be OK. You can get brass hex head bolts and nuts from MACC Models: https://maccmodels.co.uk/shop/8ba-x-1-2-hexagon-brass-pack-of-10-2/ https://maccmodels.co.uk/shop/8ba-brass-nuts-2/ They do other options as well Good luck Simon
  4. I like the idea of Super Phatic and have heard some good thigs about it - just a simple question: do you just wick the glue with the sheets already pushed together like you would for cyano or do you open up the joint and apply the glue in the same way as for normal aliphatic. I assume it is best to wick it in but I have never used this stuff! Thanks Simon
  5. https://bmfa.org/laurie-peake-1953-2021 Probably not what you wanted to find out. Simon
  6. Thanks for all the replies - it sounds like I have got the right method but I need to be a bit more careful / skilled! Simon
  7. I apologise if this has been covered before or is too basic a question but: What is the best way to glue balsa sheets together for wing skinning etc.? I usually start by taping the sheets together on a flat surface then open up the join, add some aliphatic and put back down on the flat surface with a few weights. It works OK but I always end up with a very slight mismatch in angles, a glue line that is difficult to sand out etc. Does anyone have a fool proof method that gets good consistent results? Thanks Simon
  8. I agree that the RX should be OK if the pin block area of the PCB is checked and there is no visible damage or solder splats etc. However, be very careful with the ESC. One very likely failure mode will result in the ESC BEC outputting the full supply voltage. If this has happened and connect up with say, a 3S pack, then you will probably blow your RX and all servos attached to it. If you want to check the ESC, then try first with your 2S LiFe as the main supply and measure the voltage being supplied to the RX. If it is anything other than the expected 5V then the ESC is toast and should be thrown away. It is also possible that he BEC output will have shorted out, so when you connect your battery, be ready to disconnect immediately if anything gets hot or doesn't work as expected. Good luck Simon
  9. Originally Spektrum servos were made by JR. The DS821 is definitely a JR built unit. When Spektrum went away from JR, they kept the original JR spline design. You can still get JR arms from many different places as has already been said. Simon
  10. I have a degree in mechanical engineering and started off working as a mechanical development engineer in aerospace. Pretty soon, I realised that I wanted to understand electronics so I read Horowitz and Hill from cover to cover. After that, I ended up working mainly as an electronics engineer. A brilliant book, that makes sense of it all! Simon
  11. I finally got round to finishing off my electric Tracer. I have flown it with the following setup and it is absolutely brilliant: Motor: Overlander 3542/05 (1250KV) Prop: CAM folding 9.5 x 5 ESC: Overlander 60A Battery: 4S 2200mAh, 45C I used this prop to make sure that hand launching was easy at the possible expense of top speed. Although the speed is probably a little bit down on the i.c. version in full race spec, it is not that far short and a real adrenaline buzz. To launch you just hold it in one hand, apply full power, hold with nose up a few degrees and let go. I have made a cut-out in the wing to allow the battery to be put in without removing the wing and this needs it to be reinforced with ply spars. The whole wing and tail are covered with lightweight glass cloth put on with epoxy. I have built it with no side or downthrust but it does climb under power so would have benefitted from a little downthrust. I have got round this with a simple throttle to elevator mix (although I haven't got it right yet). A couple of pictures are attached. Give it a go! Simon
  12. I have no experience with this particular motor, and the info is limited, but might be worth looking at or at least giving Robotbirds a call to see what else they might have https://www.robotbirds.co.uk/mt2808-660kv-ccw-thread.html Simon
  13. I have been using Futaba 3008SB and 7008SB which have the same voltage specs as the 3004SBB with 2S LIPOS for ages without any problems. This thread worried me so I contacted Futaba and they have just confirmed that the 7.4V limit is for the nominal voltage level and that a battery fully charged to 8.4V is fine. So it is OK to use these receivers with a 2S LIPO Simon
  14. There definitely seems to be some sort of problem here. From the BMFA home page, if you click on the 'join us' button, you get a broken link. The same thing happens if you try the 'contact us' links. So any potential newcomer to the hobby may miss out and even give up. I suspect that this is just some minor temporary glitch but it does need to be sorted out asap. Simon
  15. According to their website they are Taiwanese. I've not seen one myself but I have heard very good things about some of their other engines from people I trust. Seems like a low risk, if you are in the market for that type on engine. Simon
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