Codename-John Posted November 17, 2011 Share Posted November 17, 2011 is your plane a seagull boomerang, it looks like from the pics, if so i had near enough the same problem with mine, would run fine for about 5 mins then dead stick, i tried everything, changed the plumbing, even changed the SC engine for a JEN one, went ok for a while but then went the same, eventually I changed that oval tank as supplied to a slec square one ( involves a bit of easy enough surgery ) and renewed the plumbing once more, changed fuel to bekra 5 % since then its been perfect, never cut once and the SC engine that i changed is now in my super air and has also behaved faultlessly Quote Link to comment Share on other sites More sharing options...
David Patrick Posted November 19, 2011 Author Share Posted November 19, 2011 That's interesting - what was the main difference with the slec fuel tank to the boomerang standard one? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted November 19, 2011 Share Posted November 19, 2011 Posted by David Patrick on 17/11/2011 10:31:03: Hi Each flight lasts about the same amount of time - 5-1 0 mins tops - I don't do anything other than take off, fly circuits then land the best I can. There have been a couple of hard landings - a couple of which the prop made contact with ground - but no nose dives until this week after engine cut out. On the first flight the engine runs smoothly - on the 2nd flight you can start to hear the engine running rough - on the 3rd flight the engine starts spluttering, you can hear engine RPM increasing and decreasing as if it's struggling. How long between these flights? Quote Link to comment Share on other sites More sharing options...
David Patrick Posted November 19, 2011 Author Share Posted November 19, 2011 Between flights the time varies depending on who's at the flying field - if busy can be 10-15 mins - if not busy anything from a couple of mins to 5-10 mins - so variable Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted November 19, 2011 Share Posted November 19, 2011 Have you had any examples of the rough running occurring on a subsequent flight when there was a significant time between flights - say 30 minutes or more? Edited By Martin Harris on 19/11/2011 10:35:48 Quote Link to comment Share on other sites More sharing options...
David Patrick Posted November 19, 2011 Author Share Posted November 19, 2011 Hi - i can't remember any occurrences of rough running when i first started learning where the flight times were further apart. There's definitely a build-up of something or other. The other difference i guess with the first flight is the tank is emptied after each flying session - but just refilled after each flight. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted November 19, 2011 Share Posted November 19, 2011 Just ran through the previous posts and you don't seem to have mentioned whether you have ever changed the glow plug as advised...if not, stick an Enya No.3 in it and see what difference that makes... Quote Link to comment Share on other sites More sharing options...
David Patrick Posted November 19, 2011 Author Share Posted November 19, 2011 plug has never been changed - even after run-in - i've an os no 8 on order which seems to be a good all-rounder. the plug which came with the engine was a OS no 6 aka A3. I know the difference between the two is heat - A3 = hot, No 8 = medium heat but haven't a clue what this means and whether i've ordered the right thing! Have i done the right thing or is the Enya equivalent to No 8? i run with 10% nitro fuel which is recommended but others have said they run with 5% nitro and again - haven't a clue about that either... THanks Quote Link to comment Share on other sites More sharing options...
David Davis Posted November 19, 2011 Share Posted November 19, 2011 ".... stick an Enya No.3 in it and see what difference that makes..." or a Model Technics Fire Power FF7. I use these in everything. Finally, have you tried using some different fuel. We had a case of an engine constantly stopping at the flying field recently. Someone offered them some fuel from the fuel he'd brought to the field and the engine ran perfectly. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 21, 2011 Share Posted November 21, 2011 Posted by David Patrick on 19/11/2011 10:40:16: plug has never been changed - even after run-in - i've an os no 8 on order which seems to be a good all-rounder. the plug which came with the engine was a OS no 6 aka A3. I know the difference between the two is heat - A3 = hot, No 8 = medium heat but haven't a clue what this means and whether i've ordered the right thing! Have i done the right thing or is the Enya equivalent to No 8? i run with 10% nitro fuel which is recommended but others have said they run with 5% nitro and again - haven't a clue about that either... THanks David...I've replied to your PM..... I can't see the plug being at fault....dodgy plugs usually cause starting problems & poor running but its unlikely that a plug would be fine initially & then start to cause problems....they tend to work OK or not at all in my experience.... Just fyi David the different heat ratings of various plugs affect the ignition point of the fuel. A "hot" plug will fire the mixture earlier for a given set of conditions than a "cold" plug. You would normally run a "hot" plug with "cold" fuel (ie low nitro fuel) & a "cold" plug with a "hot" fuel (ie high nitro). With the typical 5-10% nitro fuels in general use a medium to hot plug will be fine. Correct plug selection is usually more important to competition flyers needing the last drop of power from an optimised powertrain when using very high nitro (>30%) or indeed when using a zero nitro fuel (pylon racers).... To my mind there must be something amiss with the fuelling.....its the only thing that "changes" during a flight......I'm leaning towards a hidden split or a foreign body somewhere.....or simply a dodgy tank installation if we takes Neils experience..... Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted November 30, 2011 Share Posted November 30, 2011 David brought his engine over to me yesterday to have a little looksee. I had a quick look at it last night & everything does seem fine.....usual lovely OS quality etc but one thing did confuse me. It is fitted with an OS no 6 plug as David notes above & this is really short.....I compared it with a true "short reach" plug & it is a fraction longer than that (by about 1 turn of thread) but is a good bit shorter (about 3 turns of thread) than a standard "long reach" plug & when fitted to the engine the plug doesn't actually reach the combustion chamber proper but is recessed & about 3 turns of thread are exposed. I don't think this has any bearing on the problems David is experiencing but I did find it strange... Quote Link to comment Share on other sites More sharing options...
graeme jones Posted December 20, 2011 Share Posted December 20, 2011 To David Patrick - have you solved this one yet? I've only just come across this thread. I'm interested because it may have some bearing on the thread I started a few days ago about water contamination of fuel. Quote Link to comment Share on other sites More sharing options...
Ben B Posted December 20, 2011 Share Posted December 20, 2011 How about this for lateral thinking- Increased noise in flight is an unbalanced propeller which is causing fuel foaming leading to cutting out. On the ground this isn't happening because the plane is sitting on the undercarriage. Try a different propeller Quote Link to comment Share on other sites More sharing options...
Christopher Mayers Posted December 20, 2011 Share Posted December 20, 2011 Just fired up my OS46 LA after 10 years in a cupboard. Sings like a bird and ticks over like a Swiss watch. I guess I am one of the lucky ones but this thread has made very good reading. Let us all know what you find out. Chris Quote Link to comment Share on other sites More sharing options...
John Payne Posted December 21, 2011 Share Posted December 21, 2011 Hi David, just caught up with this thread. Sorry to hear about your problems, unusual for an OS. One thought occurred to me on looking at the photos of the tank. You mentioned that the tank had "clunked" ( the clunk weight had gone forward ) and a way of stopping this is to put a short piece of brass tubing in the silicon pick-up tubing in the tank. Cut the tubing in half and put in a piece around an inch and a half long ( about 40mm for you new boys! ) and then shorten the silicon/brass tube to its' original length. No need to push the brass into the middle of the silicon so it is completely covered, just a normal connection each end of the insert. The final assembly would be - clunk weight/silicon tube/brass tube/silicon tube/tank outlet. (if this doesn't make sense, let me know and I will get a photo). This will have the effect of stiffening up the pick-up piping and stop it bending in the middle. Make sure the clunk weight stll misses the bottom of the tank. Might not stop the engine cutting problem, but it will stop the tank "clunking" on a "less than perfect" landing. Another thing to check is the pick-up nipple on the silencer that the pressure pipe connects to. Make sure it is clear as this would stop the tank breathing properly and cause a partial vacuum as the fuel gets used up. Seen this one a couple of times. Hope these thoughts help. Hope you can fix it OK and get back to enjoying your flying. Cheers, John. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted December 21, 2011 Share Posted December 21, 2011 Davids OS is currently living with me at the Hargreaves Engine Political Correction Facility....I am sending it on early morning runs followed by cold showers & lots of lectures on how an engine should behave & why it shouldn't cut out in mid flight. I have also threatened it with an angle grinder one or twice....a sort of good cop/bad cop routine... In all seriousness though I have stripped the engine down & its is all fine inside.....no evidence of any blockages or of anything else amiss (apart from the threadlock eh David!!! ) I have put it in the front of one of my models & run a couple of tanks through it on various throttle settings & using Davids fuel with no issues...it ran perfectly with an awesome tranition from idel to full throttle....really, really good. I did notice a bit of uneven running at full throttle but I think this can be tuned out by setting the needle a touch weaker. I also think that the curiously short plug I noted in a post above isn't helping in this regard too.....I also found that the main needle setting can be quite sensitive & take a while to affect the running (the main reason I personally don't like rear NVAs)...indeed at one point when I was leaning out the engine it just cut out dead with absolutely no warning. This makes me wonder if it might have been set a bit lean on the ground unbeknown to David & this will have exacerbated any problems.... The plan is to fly the model with Davids engine for a few tanks & see how it behaves in my model.....I'm just waiting for the stars to align & grant me the Holy Trinity of good weather, free time & no commitments so I can take it to the field for a test flight..... My personal view at the moment is that the engine is fine & I think the problem lies with the fuel tank installation & plumbing.....I think David is awaiting a new fuselage before he can get the model in the air once more..... But fear not Dear Reader I will share the outcome with you all......like you I do find it frustrating to suggest possible solutions & then never know if they were successful or not.... Quote Link to comment Share on other sites More sharing options...
John Payne Posted December 21, 2011 Share Posted December 21, 2011 Nice post Steve, and good to know that there are people about who can tell engines how to behave properly. By the way, if it starts to talk back I would worry if I were you........Nice one mate. Cheers, John. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted December 21, 2011 Share Posted December 21, 2011 I do find that people are jealous because The Voices only speak to me...... Quote Link to comment Share on other sites More sharing options...
John Payne Posted December 21, 2011 Share Posted December 21, 2011 . Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted January 16, 2012 Share Posted January 16, 2012 Well...the stars aligned this weekend & gave me good weather, some free time & permission to use it by going flying......a rare event indeed.... It was bloomin' cold though.....I had several jumpers & two hats on & I was still chilly.... So off to the field with Davids OS46 strapped to the front of my Wildcard along with a big chunk of lead to replicate the weight of the ASP52 that normally sits up front. I had fitted an 11x6 that I found in the drawer as this seemed most suited to the motor. I filled the tank with Davids fuel...Contest 10....& the motor sprang into life...... A minutes or so warm up & a light tweak of the needle & it was time for take off...... Away she went...off up into the wide blue yonder....slipping the surly bonds of earth or whatever it is our models do & she was away into the first circuit.....everything felt good but it was noticeable how much less power the OS46LA has than an ASP52.....to be expected really I suppose..... I had decided to keep this first flight fairly gentle to see what if anything happened.....then...disaster struck.........with a sudden bark of noise.....the silencer came loose.........er.....thats not supposed to happen....for I are an engine guru & always tighten my silencer bolts.....not this time matey......!! So a quick landing & application of the allen key saw us back on the strip for another attempt.....ahem!!! Off she went again......a nice exhaust trail standing out against the blue sky......I tried to fly a typical "trainer" flight pattern......circuits...figures of 8 & the odd gentle roll or loop thrown in when I got bored.....all mainly done on 2/3rd to 3/4s throttle with the odd burst of full power for luck......I ran the tank dry after 13.5 minutes (I usually get 9.5 with the ASP).....interestingly at about the 13 minute mark the motor speeded up & I thought..."Ooh, here we go...its running out of fuel" & then it settled down again......it continued to do this for the next 30-45 seconds as it found a bit of fuel or some fumes in the tank until the prop eventually stopped turning. As I mentioned earlier this engine seems really good at running with an erratic fuel supply. The landing was uneventful so pilot refuelled with coffee & model with Contest 10 it was time for another go.....I'll put a bit more stress on it this time I thought & flew on full throttle pretty much the whole flight.....loops & rolls & a few very dodgy Cuban 8's plus a circuit or three of inverted saw another dry tank (at 10 minutes) & the same reluctance to stop running & we were back on the strip once more. More coffee...more Contest 10 & off we went again......no mercy was shown this time.....the model was flung across the sky (well as best I could given the limited power) in some very exciting manouvers......some so "exciting" they have yet to be named .....the tank ran dry at 9 mins & 30 seconds & we were back on the ground again. At no time during any of the flights did the engine so much as cough (apart from when it was running out of fuel)....it started pretty much first time & ran like a turbine from a nice steady idle to flat out through some very challenging manouvers.....literally it never missed a beat..... So test passed with flying colours......whatever is causing the problem it's not the engine.... David.....it's back to you...........it simply must be the tank or the plumbing somewhere....a leak of some sort.... Quote Link to comment Share on other sites More sharing options...
John Payne Posted January 16, 2012 Share Posted January 16, 2012 Thorough testing Steve, nicely done. And yes, it was cold yesterday wasn't, but a lovely sky to fly against.Cheers, John. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 1, 2012 Share Posted February 1, 2012 Well, David came to collect his engine today.....it was quite a tender reunion as the two had obviously missed each other.....I had a tear in my eye at one point.... So David is going to bolt the motor into his new fuselage & do some ground runs to see if everything behaves....then on to the flying bit.... Fingers crossed for you....lets hope it all works...... Quote Link to comment Share on other sites More sharing options...
David Patrick Posted February 20, 2012 Author Share Posted February 20, 2012 A big thanks to Steve up to now - and I finally managed to get to the flying field today - a bit windy - a few drops of rain but today was all about ground testing. I filled up as usual - started as usual and kept the first test run to about 15 minutes. Motor ran well as expected - still a little rough around 1/2 throttle though. I taxied around for a little while and then brought the plane back for run #2. I refilled as usual started up as usual - engine still running fine but usual slight rough at 1/2 throttle again. Taxi run cut short this time due to gust of wind under the wing and tipped the nose in to the soft grass.... The third run was interesting - I filled up again as usual - started as usual but decided to let the engine run until the tank ran out - which it did a good 20 (or could me more like 25) minutes later (large tanks in the Seagull). What was interesting was the engine ran much better in the 2nd half of the test. There doesn't seem to be any problem with tubing or air leaks which was suspected before - the engine ran fine - without missing a beat in the last 10 minutes today. That's where I had to leave it for today - but some food for thought - at least I had three good runs ranging from 15 - 25 mins. I did end up replacing the fuel tank to another replacement Boomerang "standard" fit - so something could have been wrong with the original - or the carb I replaced a while ago... but what I do find interesting was the last 10 minutes today - engine ran smoothly across the whole rev range - and I left it sat at 1/2 throttle for a while. The engine noise decreased (for some reason) during this last run which coincided with the engine running smoother.... So I wonder why with less fuel in the tank the engine seems to run better (or at least it did today) Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 22, 2012 Share Posted February 22, 2012 Next step......FLY IT!!! Come on David you know you want to....... Good luck..... Quote Link to comment Share on other sites More sharing options...
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