Martin Ulyatt Posted July 20, 2016 Share Posted July 20, 2016 right then time has come to get above engine set up properly , i have bought a tacho thingy to help the job but not really knowing the rite way to go about it Any help would be gratefully received Quote Link to comment Share on other sites More sharing options...
.. Posted July 20, 2016 Share Posted July 20, 2016 Is it new ? If no how much work has it done ? Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 20, 2016 Share Posted July 20, 2016 What exactly do you want to know Martin? Have you run a glowengine before? The instructions will be a good place to start but basically use an OS F plug....5 or 10% nitro fuel preferrably with no castor in it. Fit a 13x6 or 13x8 prop, open the needle about 2 turns......fill tank with fuel......choke for a couple of turns of the prop....apply glow battery & spin the engine until it starts..... Does that help? Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 20, 2016 Share Posted July 20, 2016 The Tacho will become more useful Martin as the motor is fully run in. If your desire is to improve the tuning of a run in motor, then peak the motor by turning in the main needle until your Tacho shows the highest figure with that prop, then turn out the main needle very slowly to deduct 200rpm from the top figure achievable. This setting is just on the rich side of lean, and is the safe side. Allow the motor to idle, without stalling, and measure the rpm. We should be able to get this down to 2000rpm, that is great for landing. If the motor has an unreliable tickover above 2500 then more running in until you can get a good idle at 2000rpm Quote Link to comment Share on other sites More sharing options...
Martin Ulyatt Posted July 20, 2016 Author Share Posted July 20, 2016 I bave looked at instructions , ive had 3 tanks of fuel through engine on a test bed ( new engine) it has osf plug in and 13x8 prop I just wanted to set engine up so can fly plane , 1st glow engine plane after flying electric ones , thanks everyone for helping me Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 20, 2016 Share Posted July 20, 2016 Posted by Denis Watkins on 20/07/2016 20:50:24: The Tacho will become more useful Martin as the motor is fully run in. If your desire is to improve the tuning of a run in motor, then peak the motor by turning in the main needle until your Tacho shows the highest figure with that prop, then turn out the main needle very slowly to deduct 200rpm from the top figure achievable. This setting is just on the rich side of lean, and is the safe side. Allow the motor to idle, without stalling, and measure the rpm. We should be able to get this down to 2000rpm, that is great for landing. If the motor has an unreliable tickover above 2500 then more running in until you can get a good idle at 2000rpm I would recommend against tuning the engine in this way. Tuning while looking at the tacho will likely lead you to run much to lean. If you listen very carfully and hear a harsh cracking sound hidden within the overall note of the engine then that is a sign you are too lean. If however the engine holds max rpm without sagging then you are just fine and can go and fly. There is no need to run the engine 200rpm rich of the peak. You are giving away performance needlessly and wasting a significant amount of fuel. Tune the engine by ear, if it sounds good then it probably is. Don't do a nose up test as it is unrepresentative of what the model will do in flight (unless you prop hang) and only leads to an excessively rich mixture. If the engine slows down and dies after a few minutes in the air then it has overheated. Overheating and being too lean are different things and most engines will not be able to maintain full power constantly without overheating. A test for this would be to let the engine cool, restart it and fly again without refuelling. If the engine dies straight away then the lower tank level has sent the engine lean and you need to move the fuel tank a bit. If the engine works fine then slowly dies as before then it has overheated and you need either a better cooling arrangement or to fly with less throttle. Ie throttle back when in a dive, and up again when climbing. You will save a lot of fuel doing this as well so its win win! Quote Link to comment Share on other sites More sharing options...
Martin Ulyatt Posted July 21, 2016 Author Share Posted July 21, 2016 Thank you for your help Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted July 21, 2016 Share Posted July 21, 2016 I would agree tacho's not needed to set bottom/top end, needs to be set so pick up and running is right, rpm is irrelevant and it'll change according to prop size, putting the nose up to check before flying is a simple test which will show if you've set it lean and is worthwhile, a take off, loop, stall turn are pretty much representative, it's a test that's probably saved more deadsticks than any other method you could mention. John Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 21, 2016 Share Posted July 21, 2016 The nose up test will only prove an engine is too lean while pointed vertical at full chat and not moving forwards. Even during normal aerobatic flight this will never happen. A loop is done with forward speed, and a stall turn is done at reduced throttle to allow the model to decelerate. For these reasons it is unrepresentative of conditions found in flight and is really pointless. I have not done a nose up test in over a decade and never suffer from lean cuts in flight no matter how much i abuse the model. I know it has become a fabled part of modelling folk lore, but it really serves no purpose im afraid. Quote Link to comment Share on other sites More sharing options...
Martin Ulyatt Posted July 21, 2016 Author Share Posted July 21, 2016 Thanks everyone , bin great help to a excited newbie Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 21, 2016 Share Posted July 21, 2016 You guys are experts and can fly, and you can tune a motor. Have you forgotten how it feels to be a page one, brand new? Newbie I offered Martin a Way Forward with his Tacho that does work, Your offer of him tuning by flying does work for EXPERT flyers Here is a Newbie Consider page one boys, start with an understanding that not all of us as clever as you Guys come on here for help Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 21, 2016 Share Posted July 21, 2016 Martin, PM me if you want to know how to fly or how to tune correctly Quote Link to comment Share on other sites More sharing options...
.. Posted July 21, 2016 Share Posted July 21, 2016 Denis , you need to get over yourself a bit & stop commenting on the advice given by others. Martin has come back & thanked people for the info and I'm sure he will be back again when he needs more. Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 21, 2016 Share Posted July 21, 2016 I remember well learning how to tune engines and it was always by ear. When teaching at my club (i am CFI) i also spend a great deal of time with newbies showing them how to set up engines and what to look/listen for. Even an engine that wont even run/fire at all is telling you why if you know what to look for. I dont recommend using a tacho to tune for several reasons. First, chasing rpm is a real problem for people with tacho's. It was doing 8500rpm yesterday so why only 8300 today? And they sit there at full chat for ages and ages fiddling away trying to get their 200rpm back. most liklely, the conditions of the day mean that 8300 is all you are going to get so by twiddling at it all you will do is waste flying time and most likely end up with incorrect tuning. The second issue is similar to the first. If you open up a cold engine to full power and tune it for max rpm you will find that it will rev faster than when it is hot due to expansion of the various parts (there are exceptions to this). So if you peak your engine to 8500 again, then tweak the needle, and check again with the tacho to see 8300 you are back where you were before. fiddling a faffing about for no reason at all. If it holds max rpm for 10 seconds then its not lean, go fly! A tacho is a great tool, and its very useful for keeping an eye on engine performance and for comparing different props etc. There is however such a thing as too much information and for many years engines were tuned by ear in total ignorance of the rpm as it was not actually important. This still holds true and a little time spent learning what to listen for will be very helpful as lean runs in the air can be detected by the engine note before serious overheating sets in. Also Denis come on. I make glow engines for a living, i fly regularly at shows and you have said yourself that i am an 'expert' so instead of trying to push your own ideas with private messages why not listen to and heed my advice as there is a fair to middling chance i do know what im talking about. Im not trying to put you down, but as you have said, people come here to learn and correct information is vital to prevent them going to wrong way and suffering because of it. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 21, 2016 Share Posted July 21, 2016 Posted by Denis Watkins on 21/07/2016 14:55:44: You guys are experts and can fly, and you can tune a motor. Have you forgotten how it feels to be a page one, brand new? Newbie I offered Martin a Way Forward with his Tacho that does work, Your offer of him tuning by flying does work for EXPERT flyers Here is a Newbie Consider page one boys, start with an understanding that not all of us as clever as you Guys come on here for help I don't think any of us have forgotten what it feels like to be a Newbie Denis & as far as I can see all the other members are offering good advise....just because Martin HAS a tacho doesn't mean he has to use it & like Jon & John I too would never use one to tune an engine either. Indeed if I was helping an beginner at the field I would dissuade them from using a tacho too.....how does doing the wrong thing, better, help anyone? Martin may have bought a tacho because he thought or was told he needed one. That's fine....that's one point of view. The majority of flyers learn to tune without one & we are suggesting to Martin that this is the best way forward. Martin, modern engines need very little running in....if it's had three tanks of fuel through it then it will be more than ready to put in a plane.... When tuning an engine the trick is to get the engine running as fast as you can but as rich as you can. 4 strokes tend to have a very flat peak when leaning out the needle.....you will find that the revs increase as you screw in the needle until the revs reach a maximum.....you can continue to screw in the needle & notice no increase in revs.....BEWARE....your engine is now too lean. So as you screw in the needle listen for the increase in revs....when they stop increasing stop screwing in the needle & unscrew it slightly until you hear the revs drop again....then slightly in again & you are there. Do be careful....all adjustments must be made from behind the prop....the prop disappears at high revs & it is all too easy to catch a finger or worse. This hurts....! Despite the excitement do make sure you keep your wits about you.... Enjoy your engine...... What model is the SC destined for by the way? Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 21, 2016 Share Posted July 21, 2016 Sorry guys, continue the good work Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted July 21, 2016 Share Posted July 21, 2016 Yep lighten up Denis, john disagrees with me, it's no biggie Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 21, 2016 Share Posted July 21, 2016 Posted by john stones 1 on 21/07/2016 21:22:21: Yep lighten up Denis, john disagrees with me, it's no biggie Quote Link to comment Share on other sites More sharing options...
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