Andy Stephenson Posted March 4, 2021 Share Posted March 4, 2021 I'm looking at the only way of making a throttle linkage is to have a length of piano wire linked directly to the throttle arm via a joggle. I know this was a problem on MHz radio and I have heard rumours it might affect 2.4 gear. Does anyone have any evidence of this? Andy. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 4, 2021 Share Posted March 4, 2021 If link has a ball/socket fitting, there is no metal to metal, question becomes redundant. Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted March 4, 2021 Share Posted March 4, 2021 Was it ever a real phenomenon anyway? I honestly don't recall anyone having the problem other than blaming a crash on some spurious ideas and guesses. During one of the panics about this back in the day, I recall trying to reproduce some sort of malfunction using various methods both at close and long range from a TX within a model and with a RX and servos set up on a board and never ever got even a twitch from the servos. The only reaction I could cause reliably was to run a metal comb down the extended TX aerial and then that would give the servos a twitch or two but not the same thing at all. If you're worried Andy, just electrically bond the metal parts together. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted March 4, 2021 Share Posted March 4, 2021 12 minutes ago, Cuban8 said: If you're worried Andy, just electrically bond the metal parts together. Piano wire & metal throttle arm? I'd go with one of these doodahs https://www.ebay.co.uk/itm/Wire-Rod-Quick-Adjustable-For-RC-Airplane-Push-Link-Plug-Servo-Connector/274441989506?hash=item3fe6046d82:g:tR8AAOSwImBfIE8R Of course one nut doesn't mix with vibration - add a locknut or use threadlock... Drop of threadlock on the set screw as well. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 4, 2021 Share Posted March 4, 2021 Off topic a bit, but I would use a ball link. I don’t think 2.4 radio cares a jot about metal to metal interference, but IC engines do care about slop free linkages. I can attest it did exist back in the day. I remember an entertaining maiden. Anything round half throttle, and it was near uncontrollable [extra type from memory). Full chat OK, tick over, twitchy. Turned off the motor off, landed it. Reproduced symptoms on the bench. Replaced the metal link, to engine metal arm with a plastic link. Never an issue thereafter. Met its end with an ill judged low inverted pass. When I dared to do such things. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted March 4, 2021 Author Share Posted March 4, 2021 The only problem I have is that I have to trim quite a lot more off the cowl to allow the sleeve of a ball link or clevis not to catch when closing the throttle. This may however, end up being the only solution. I looked at bonding but this would add enough stuff to the mechanism as using a ball link. I have personally seen metal to metal interference on MHz radio so this isn't an imaginary effect. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 4, 2021 Share Posted March 4, 2021 One of those plastic links work. A way round any fear of failure, or slop, is to put a small spring in the circuit, closing the throttle. Removes slop, and if the plastic link fails, you get a dead stick. Not likely, or the end of the world. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted March 5, 2021 Author Share Posted March 5, 2021 I'm not prepared to compromise on a throttle linkage and especially not on a pattern-ship. After a lot of trial and error I found a ball link that will fit on the inside of the arm which I had to bend slightly. With a chamfer on the sleeve of the ball link I am satisfied I have found a solution that will work satisfactorily and I won't have to test the theory that metal-to-metal interference is a thing on 2.4. Thanks for all the suggestions. 2 Quote Link to comment Share on other sites More sharing options...
Nigel R Posted March 5, 2021 Share Posted March 5, 2021 Now that is a tight cowling. OS RF? Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted March 5, 2021 Share Posted March 5, 2021 I have never experienced any Metal to metal interference while using 2.4 but have experienced interference being picked up by the servo or the servo leads when placed at front near the ignition unit and making servos go wild especially at lower rpm. This is very similar to metal to metal interference we experienced when using 35 meg radio. I now fit the throttle servo further back away from the ignition system and use a plastic snake for the run . Never had an issue since . Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted March 5, 2021 Author Share Posted March 5, 2021 (edited) Nigel, The cowling would have been even tighter if I hadn't cheated with the dimensions and widened the fuz a few mm and the cowling won't even go on unless I remove the cylinder head first and the whole thing was made worse because the engine has an enormous heli carb. A. Edited March 5, 2021 by Andy Stephenson Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 5, 2021 Share Posted March 5, 2021 What engine Andy ? Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted March 5, 2021 Author Share Posted March 5, 2021 John, It's an OS 61 RF which was sold off by Just Engines at the Sandown show a few years ago. I bought it for spares but have recently pressed into into service. I believe it was originally a heli engine but how a rear exhaust engine would work in heli orientation, I'm not sure. The prop driver doesn't quite fit as some of the keyed shaft is exposed and the thread on the shaft is only 1/4" as opposed to the proper aero version which used 5/16". It's a strange one at it has an aero head. I suspect they were bitzas put together from spares so they could sell them off. 1 Quote Link to comment Share on other sites More sharing options...
David P Williams Posted March 5, 2021 Share Posted March 5, 2021 The Graupner/Heim helis used the rear exhaust OS61s Quote Link to comment Share on other sites More sharing options...
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