Charles Aldous 1

Thanks for the filing tip. As I'm setting some "toe in" what I'm also interested in is once I have set/adjusted the 4 flats on the leg side, how best to mark the spot to make the first flat through the set screw hole on the trunion side of the pin, once the leg has been offset slightly? I think once I have a decent flat on one side, giving the correct angle of offset, I can use calipers to make the opposing flat match it?

I've filed flats for undercarriage legs before, but never very accurately or neatly and usually just on piano wire legs. As I am installing Electron retracts with beefy pins I'm looking for pointers of the best method and steps involved to do a decent job please. The units have single set screws for the connecting pin on both sides of the trunion and dual set screws on both sides of the legs. Any advice most welcome, TIA Charles

Posted by Denis Watkins on 24/08/2020 12:23:44: Am reading with interest as a decent biplane is my next target. I hope I don't loose you on this Charles, but if you fall in the canal and are unable to swim, and see a passer by Would you rather they had read the book and all the reviews about lifesaving Or would you rather that they were someone who owned the subject fully and practically like Low Pass Pete. Very interesting and informative thread Thanks Denis. I reckon I am now amongst the converted to whom you so eloquently preach. Hats off to the contributer's

Thanks Peter, all good info. I think having read all the reviews I can find, I need to stick to the remit I set myself, which was to choose a model that is capable of decent aerobatics, few or no vices, easy to rig and using my OS 120, have plenty of power in reseve. Also something I won't be tempted to spend hours of angst about improving sclae looks! I love the Jungmeister look but it really is pretty similar in style to the GP Super stearman I have just agreed to sell. Christen Eagle or something similar fits that bill. There was a good spec one on BMFA a few weeks ago but that was before I was on the lookout. Thanks again.

Thanks Pete. I am tempted by a Jungmeister BNIB on BMFA classifieds but concerned by your comments. How did you find yours say for rolls and loops etc? also, how big of an issue is the un-sprung u/c? Thanks in advance

Posted by Low pass Pete on 19/08/2020 11:29:11: Posted by Charles Aldous 1 on 19/08/2020 10:33:24: Thanks for replies: I like the look of the Christen Eagle and research would favour the Hangar 9 version but discontinued, which leave the Seagul one which is reasonably well thought of. The other model I like the look of is the Seagull Bucker Jungmeister, 65" wingspan. I have both of these models. Ref Jungmeister- Mine has a Laser 155. I would not recommend a smaller engine than this. It would struggle on a 91. Ref Christan Eagle - Mine had an OS 120 and it flew very well on this, but I feel on a 91 it would be underpowered and climb rate would be poor. The Eagle is much like a Pitts so likes power. Not a model for a beginer. Hope this helps Peter Edited By Low pass Pete on 19/08/2020 11:29:38 Hi Pete and thanks for reply. I have an OS 120 in stock which I could use for a Christen, but would that be adequate for a Jungmeister (unsure of Laser 155 output)? I want to fly spirited aerobatics in due course and wonder which model is your favourite? I like the scale looks of the Jungmeister over the Christen.     Edited By Charles Aldous 1 on 19/08/2020 13:04:38

Thanks for replies: I like the look of the Christen Eagle and research would favour the Hangar 9 version but discontinued, which leave the Seagul one which is reasonably well thought of. The other model I like the look of is the Seagull Bucker Jungmeister, 65" wingspan.

Thanks Richard. Martin, it is artf I'm looking for.

I have a faithful OS 91 fs looking for a new airframe and I fancy a suitable, aerobatic biplane. This engine once flew a Great Planes Super Skybolt, 77" wingspan and a little under 8lbs, so something similar would suit. Any recommendations welcomed please.

Posted by Nigel R on 16/08/2019 13:35:42: Charles reading the page you link, something immediately jumps out: "Therefor the minus pole can be bypassed with an external power resistor." and the caution at the end of the page: "CAUTION: There must not be an electrical connection between the drive battery's minus pole and the receiver respectively the receiver current supply! When using some telemetry sensors this ground connection is made by the sensor respectively by its electronic. So the receiver can be damaged. When using such products the usage of the SPS SafetyPowerSwitch is not possible" This is almost where you are at, I think. These two statements on the information page, imply to me that only the negative connection is switched. No particular issue there. However. This would infer that the positive connection from lipo to ESC is permanently in place and that part or all of the ESC could be at the positive voltage of the lipo. If the BEC ground output seen by the RX is markedly lower, and if the RX is checking that the signal terminal is within 0V to 5V (i.e. inside its own supply voltage), that check would fail under this circumstance. This is not a great place to be, electrically. I would try using this negative bypass resistor. A 10W 470ohm resistor is not expensive. Edited By Nigel R on 16/08/2019 13:39:04 Edited By Nigel R on 16/08/2019 13:48:38 Hi Nigel, Many thanks for this latest post which sounds the likely diagnosis. I'll check this out further when back home end of next week. Would you have a link to a suitable resistor please and how I should connect it? Much thanks to the other contributors on this thread and I'll advise outcome in due course. Regards Charles

Posted by Nigel R on 16/08/2019 10:24:04: Emcotec is a solid state switch. I don't know whether it switches ground or positive or both. I'm presuming it is FET based as most such things are. There will be capacitance and high resistance across the switched connections when the switch is disengaged (i.e. ESC off). This may, depending on the ESC, produce an undesirable voltage level to be presented to the throttle signal connection. The 620 (and other same generation RXs) may well be verifying the voltage on each pin during powerup before it starts up in order to protect the RX circuitry, before it starts normal operation. I would try removing the fancy dandy solid state switch from the equation, for the purpose of sanity checking several scenarios: That is, 1 Lipo -> BEC -> RX throttle signal wire only, connected to ESC absolutely no other connection to ESC. 2 Lipo -> BEC -> RX Lipo negative -> ESC throttle signal wire only, connected to ESC 3 Lipo -> BEC -> RX Lipo positive -> ESC throttle signal wire only connected to ESC Edited By Nigel R on 16/08/2019 10:25:39 Thanks NIgel and I think you are on to something regarding the capacitance etc. I am not overly electrically savvy but the set-up I use works flawlessly except with this new AR620. The AR620 works fine with the safety switch once the esc has has been powered up by releasing the switch and then can be isolated again with the switch. I have tried most or all of the permutations you kindly suggest but will re-visit later. See link below for tech specs etc of switch http://wiki-en.hacker-motor.com/index.php/SPS_SafetyPowerSwitch

Posted by Cuban8 on 16/08/2019 07:27:13: Diagram is exactly as I expected & looks fine. Where you say 'signal wire only' presumably you mean the +ve ESC BEC supply is disconnected, leaving you with two conductors in the plug i.e signal and 0V into the throttle port (from which the RX would usually get its power from a BEC/ESC). Common ground running through the components, so shouldn't matter. Have you tried removing the external BEC supply from the RX's battery port and supplying the RX via a spare servo port instead? These are normally all part of a single 'bus' common to all the servo connectors at the side of the RX, but there's something strange about the 620. Thanks. Signal wire only, otherwise esc arms, by-passing safety switch....this set-up works fine with older type spktm rx's. Have tried sparate pack to supply rx and esc arms normally. Edited By Cuban8 on 16/08/2019 07:40:33

Hi Andy, Thanks for link. Take a look at reports 608/9 using the link you posted. I am assembling a Sebart Angel 50 which is pretty simiilar to the Mythos. Regards Charles

Thanks Steve. Disconnecting as you mention above made no difference, rx still only powers up when switch opened. I double checked that tha bec is live to rx when lipo connected1 I'll take a look at the link.

Hi Cuban, wiring diag below I can work around this issue just by opening the safety switch, which allows the esc to arm and power up the rx, then close the switch for safety. Just don't understand why the esc prevents the AR620 from powering up until it sees power, when other spektrum rx's don't have this issue?  Edited By Charles Aldous 1 on 15/08/2019 21:32:49