john stones 1 - Moderator Posted October 31, 2022 Share Posted October 31, 2022 I'm curious, is there a difference in the make up of Laser engines compared to O.S etc that negates Laser having the same carb position, or are you saying O.S etc are compromising performance with their positioning ? 2 Link to comment Share on other sites More sharing options...
Chris Walby Posted October 31, 2022 Share Posted October 31, 2022 25 minutes ago, Mike Mc said: Explaining stuff over and over is all part of good customer service. No its most definitely not! Good customer service is about being accessible and providing good advice. Jon excels at this to the point that his advice is impartial and may advise selecting a competitors engine that is better suited to the required installation. The point of forums like this is so that people can read discussions (if they can be bothered) and not keep asking the same repetitive questions. Okay people will go against the advice of the manufacturer and then other people can then see the error of their ways. Perhaps Laser should detail things on their web site that you should not do, but as the saying goes "you cannot anticipate the ingenious idiot" Read the posts and discussions, if in doubt ask Jon to clarify any misunderstandings you may have and carry out the installation as recommended by the manufacturer. Surprise surprise the engine will perform well and be reliable. I just don't get it, Jon spends hours and hours designing and building engines and people come along and want to run them with special arrangements or put things in odd places or add complexity. A Laser engine is better than its sum of parts, because its well designed and tolerant of a wide skill set operating it. Please let Jon get on with engine building and development (more of the FT and inlines...and we may be lucky one day a radial) but one thing is guaranteed, it will be reliable if installed correctly. 1 Link to comment Share on other sites More sharing options...
Jonathan W Posted October 31, 2022 Share Posted October 31, 2022 I'm also curious about this carb position issue. Not doubting what Jon is saying about worse performance if using the "Japanese position", but in what specific way is it worse? In full size automotive practice, a longer inlet duct (within reason) is nearly always beneficial to everything, especially mid-range torque. That is the case whether a pre-throttle inlet trumpet, or a post-throttle long inlet manifold runner. It's usually only top end power in higher revving engines that benefits from a shorter inlet length. So what aspect of the Laser performance is reduced by moving the carb down? Link to comment Share on other sites More sharing options...
Jon H Posted October 31, 2022 Author Share Posted October 31, 2022 1 hour ago, Mike Mc said: Explaining stuff over and over is all part of good customer service. Chris beat me to it, but no it isnt. My job is to give the right advice, which is fair enough and part of the expectation. But, having given that advice it unreasonable to expect me to reiterate it every day, and spend hours and hours explaining why and defending it. Its also unreasonable for someone to completely ignore it, and then expect me to help. What more can i do? i gave all of the advice, you ignored it...I cant do any more than reiterate all of the advice i already gave. Perhaps its because of my accessibility, i am easy to contact and chat with, i post here on the forum and shoot the breeze on a variety of subjects. But for some reason there seems to be a perception that i am just putting forward my opinion, my view point which can be adhered to or ignored as you please. Or perhaps the fact that we seem to live in a world of 'alternative facts' where everyone is allowed an opinion and no-one is ever wrong about anything. This is very much not the case and where i come from, the facts do matter. I also think many people forget that i am the only one here. One man in all the world responsible for looking after every laser engine ever made. If i have to spoon feed and hand hold everyone by explaining in detail why i recommend the things i do, i will not only never get anything done but i will also go mad. The recommendation is there, just do it. I have already discussed this with the boss and are seriously considering changing the way we operate so the company will not be open to communication from end users like OS and Saito as its getting to much and there is only so much one man can take. Like it or not, the manufacturer of the product you operate knows more about it than you. This is why i asked redfin for advice on what fuel to use in the little diesel i recently bought and why i sent my PAW engine back to them to sort out the scored liner. They are the experts on those engines and i will simply do as i am told when it comes to operating their products. Ok so bendy intake tubes like OS and Saito. Short intakes straight into the head are the best for performance. Just take a look at almost any motorbike engine, the carbs are right there on the head. Model engines are more closely aligned with bike engines than car engines given their operating rpm rage. And before someone posts a lists of exceptions, i dont care. Remember, i have written this post about 100 times as well. Also many automotive applications these days are fuel injected with MAF and Lambda sensors looking after everything. So in the case of model engines inverted the biggest issue is fuel pools in the elbow at low rpm. Fuel is denser than air and it centrifuges out going round the corner. You can also get water condensation in there as well. So the engine is chuffing away and you open the throttle to take off. Once past a certain point the airflow picks up the pool of fuel and draws it into the engine. Best case, cloud of smoke, but more often that not it will cough and splutter its way to full power or cut out 10 feet down the runway. If anyone claims they have never seen that happen i call male cow pats on that. This fuel pooling problem is worse when you have a rich slow run needle...and how many modellers really maximise or even touch their slow run needles? So to conclude this epic A very large part of the almost mythical laser reliability is down to our carb placement. Even with dreadful tuning and tank placement the engines are often very reliable. A tiger moth for example, flown in flat circuits would probably be fine with the tank up in space even though it chews up fuel like its going out of style and leaks all over the floor when the engine isnt running. The problem is, that guy might recommend that tank setup to someone with a stampe who wants a more aerobatic performance and then it will not work at all. Equally, it would not work at all with the tank high if we had an elbow. 'Ah but tank placement is easier to get right with an elbow' you all cry. Sure, but you suffer loss of performance and all of the fuel pooling problems even if you do tune it right. Im loosing the will to live now so..im done. Time for a chocolate hobnob to recover my senses. 5 3 Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted October 31, 2022 Share Posted October 31, 2022 Well can't say I've ever struggled re tank positioning myself, put it where it needs to be, job sorted. Thanks for the clarification re carb positioning on the various makes, curiosity satisfied. Regarding repeat questions and customers, having a live thread inviting questions I should stock up on Hobnobs. 1 Link to comment Share on other sites More sharing options...
Jonathan W Posted October 31, 2022 Share Posted October 31, 2022 One sentence about fuel pooling in the inlet pipe answers it for me, thanks!! Link to comment Share on other sites More sharing options...
Jon H Posted October 31, 2022 Author Share Posted October 31, 2022 50 minutes ago, john stones 1 - Moderator said: Well can't say I've ever struggled re tank positioning myself, put it where it needs to be, job sorted. Thanks for the clarification re carb positioning on the various makes, curiosity satisfied. Regarding repeat questions and customers, having a live thread inviting questions I should stock up on Hobnobs. I dont find it difficult either. I cant understand why it is such a big problem. As for the thread, its here for people to ask technical questions and not repeatedly go over old ground again and again, or argue the toss about the recommendation being right or wrong. I need to lay off the hobnobs though. At modelair a month or so back i bumped into a customer i hadnt seen in a while and the first comment he made was about how fat i now was. Cheeky so n so. He was lucky i didnt run him through with an apc prop. He seemed to think it was hilarious, i was actually quite offended. 1 1 Link to comment Share on other sites More sharing options...
John Tee Posted October 31, 2022 Share Posted October 31, 2022 Patience of a saint (if wearing a bit thin)😃😃😃 John Link to comment Share on other sites More sharing options...
Eric Robson Posted November 1, 2022 Share Posted November 1, 2022 Hi Jon, I can understand your frustration so why not have a stock answer that you just post every time this comes up. The problem is the thread is in it's 93rd page so many questions have been repeated. Of course the simple solution is to READ the instructions which clearly say the tank should be mounted below the carb centre line, You could in the future highlight this and quote "THE TANK MUST" not the tank should. 1 Link to comment Share on other sites More sharing options...
Jon H Posted November 1, 2022 Author Share Posted November 1, 2022 Just now, Eric Robson said: Hi Jon, I can understand your frustration so why not have a stock answer that you just post every time this comes up. The problem is the thread is in it's 93rd page so many questions have been repeated. Of course the simple solution is to READ the instructions which clearly say the tank should be mounted below the carb centre line, You could in the future highlight this and quote "THE TANK MUST" not the tank should. I dont have a problem with the 93 page tldr issue. if someone posted asking about tank placement and i answer, either in person or with a copy paste, that would be fine if they went away with the info and it was jobe done. The problem is if i give the canned answer it seems to wash over like a cool breeze and not actually make an impact. Unless i make a right song a dance out of it folk dont seem to pay attention, and even then its a 50/50 shot vs the 'club expert'. Again perhaps this is a result of our modern sensationalised world where even the mundane is exaggerated to the point of frenzy for views and attention. A quick scan of the morning papers illustrates the point. There is also a torrent of well meaning advice from other forum members, some of which is not aligned with my own and we are back to debating the issue. As its difficult for me to tell a valued customer they are wrong and to keep quiet (not in the customer service handbook that one) i have to try and argue my point, again.. This brings us to the another problem....modellers. Modellers as a group do not like change. How many times do we see comments about castor being the greatest thing since sliced bread? The fact that it isnt makes no odds because 'we have always done it this way'. Tank placement, nose up tests, castor oil, expo, running in...you name it, 'we have always done it this way'. The snag is doing something repeatedly wrong for decades does not make it right, and even if it was right then is it now? When i was younger i used to use castor fuel, and do nose up tests as...yep, that's what we had always done and my dad taught me to do it. It was only later on that i thought...why? 'This makes no sense at all' i thought to myself having nearly cut my arm off with an OS91 surpass after the model slipped during a nose up test. Perhaps i was just too rebellious for my own good but it set me on the path of challenging all of the established folk lore and i very quickly realised that most of it was a load of rubbish. An engineering degree and many years later i am trying to impart these new and fantastic ideas but get met with significant resistance as it is not the way its always been done. I am also the only one rocking the boat. Its not just on the forum either, its industry wide. I sold an engine i designed and built to a customer, and a gallon of the low oil fuel i now recommend for everything. He mentioned this fuel to the model shop where he was buying the model and they told him not to use it as it would destroy the engine. Even after he explained several times that it was the recommended fuel and that i handed him the bottle here at the factory, they kept telling him to throw it out and use something with more oil as it would ruin the engine. I then get a call from a customer in panic and spend half an hour trying to convince him its all fine. I call the shop, explain the situation and have a 40 minute argument with them as they keep saying i am wrong. I also sent an engine to model world magazine for review and they flatly refused to follow the running in instructions and instead pushed the 'run it rich for 3 weeks and then lean it off a click' line we have seen for decades. They did print my protest email in the article, but justified ignoring me with 'old habits die hard'. So what chance does anyone have of learning anything new of its just shot down immediately from every angle? Even those who have taken my advice on board and support it are ignored by the masses, so it really is an uphill struggle. 6 Link to comment Share on other sites More sharing options...
Don Fry Posted November 1, 2022 Share Posted November 1, 2022 Arrr, but all you have to do is play a patient game, and when we fall off the perch, last man standing. Look after yourself. Man shall not live by HobNobs alone. Mind try the ones Swmbo makes, bit more crunch, less sugar, devine with strong coffee. Then you get a weight problem, I’ve given up whiskey to compensate. 1 Link to comment Share on other sites More sharing options...
Eric Robson Posted November 1, 2022 Share Posted November 1, 2022 (edited) One of our club members has a Mick Reeves Spitfire with a Laser engine and complains of the mess and all his engines will be petrol from now on. I suggested using the recommended fuel to which he replied I am not going to wreck my engine with that stuff. I pointed out my Laser powered Seagull Chipmunk which has had much more use than his Spitfire, very little oil residue after a 12 min flight and still could not convince him, so you do hit brick walls Jon. By the way my CML Spitfire is petrol powered only due to the fact a suitable Laser engine was out of production. It woks very well with this set up but does not sound as good. Edited November 1, 2022 by Eric Robson 1 Link to comment Share on other sites More sharing options...
Jon H Posted November 1, 2022 Author Share Posted November 1, 2022 Eric, that is exactly what i am talking about. Knowing the Reeves Spitfire i can all but guarantee that the engine is inverted, the tank too high, the mixture too rich to compensate, and he's using a fuel with more than double the oil he needs, probably 10% nitro as well as 'this makes engines run better'. It still performs badly and makes a mess, and yet he is right, everyone else is wrong (including the manufacturer of the engine he is using) and petrol is his god given saviour. I cant even begin to understand that thought process. The guy who makes your engine is telling you you are doing it wrong, but you disagree...sure, if you say so. Dunning Kruger in full effect i fear but guess who will be the first to hear about it if something goes wrong? Yep, me. And i will be expected to fix it while still be wrong about everything. Sigh. Why people think this low oil fuel will damage their engine is beyond me. The happily put less oil through a petrol, why should a glow be different? Oh its its lubricity of petrol... Again, having posted this 100 times, petrol is a better lubricant than methanol in a quantifiable way. However, it is still a really bad lubricant. it could be 100% better than methanol, but its still awful. And as 4 stroke engines only ever have oil in the crankcase why are the lubrication properties of the fuel important anyway? I just hope he sells the 150 instead of trying to convert it to petrol. 1 Link to comment Share on other sites More sharing options...
Zflyer Posted November 1, 2022 Share Posted November 1, 2022 Jon you really don't have to keep pushing back. Just refer to which ever page has the advise on and leave them to it. They have paid there more and made their choice(s). If they are being returned to you for repair just chalk it up as another win over ignorance. Sadly I have an engine below the tank in my Tucano with no available method to lower it. Start it inverted and away I go. It bugs me that its designed that way. I bought it secondhand but I truly love it despite the pain in the rear problem. Keep smiling, go easy on the hob knobs and be aware that more of us appreciate you being here than ignore the manufacturers/designers advice and hard won knowledge. Link to comment Share on other sites More sharing options...
Jon H Posted November 1, 2022 Author Share Posted November 1, 2022 29 minutes ago, Zflyer said: Just refer to which ever page has the advise on and leave them to it. I would, but i am still expected to fix it when they ignore me and all goes wrong. Tucano's are a real problem due to the nose leg. Side mounting the engine is the only solution really but it can interfere with the looks. Then again, what is better? A nice looking model that wont fly or a slightly uglier one that will? Link to comment Share on other sites More sharing options...
J D 8 Posted November 1, 2022 Share Posted November 1, 2022 Nose up test, I had been a modeler for 25 years [ lone or with a mate ] before joining a club. First time there I was asked by the club expert why I did not do the nose up test as it was a vital engine check. I had never heard of it, I did try it a couple of times but saw no advantage, in fact it felt wrong to hold even an Irvine 40 going flat out a few inch's from one's face. Glad to say the practice has died out in our club 1 Link to comment Share on other sites More sharing options...
aidan mcatamney Posted November 1, 2022 Share Posted November 1, 2022 I agree, this practice is very dangerous. 1 Link to comment Share on other sites More sharing options...
Jon H Posted November 1, 2022 Author Share Posted November 1, 2022 As i mentioned before, when i was about 17 i had an ARC Carosel with an OS91 surpass in it. Doing my nose up test a gust of wind pushed the model just enough for the thrust of the engine to bend my wrist back. I wasnt able to hang on to it so had to do a pirouette and throw the model into the long grass. I have not even attempted a nose up test since that day. Beyond the safety issue the test is also not really representative of conditions seen in flight so it can jog on. I think the test dates back to the control line days when it was a way of simulating the centrifugal forces on the fuel once the model was whizzing around. Its the only logical explanation i can come up with. Link to comment Share on other sites More sharing options...
John Stainforth Posted November 1, 2022 Share Posted November 1, 2022 27 minutes ago, Jon - Laser Engines said: As i mentioned before, when i was about 17 i had an ARC Carosel with an OS91 surpass in it. Doing my nose up test a gust of wind pushed the model just enough for the thrust of the engine to bend my wrist back. I wasnt able to hang on to it so had to do a pirouette and throw the model into the long grass. I have not even attempted a nose up test since that day. Beyond the safety issue the test is also not really representative of conditions seen in flight so it can jog on. I think the test dates back to the control line days when it was a way of simulating the centrifugal forces on the fuel once the model was whizzing around. Its the only logical explanation i can come up with. Or to check that the clunk tube in the tank has not fallen off?! Link to comment Share on other sites More sharing options...
Ron Gray Posted November 1, 2022 Share Posted November 1, 2022 Doesn't help when some manufacturers advocate it: Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted November 1, 2022 Share Posted November 1, 2022 I do like a chuckle, and here you are revisiting the same old same old, irony, satire ? 1 1 Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted November 1, 2022 Share Posted November 1, 2022 We still have a couple of 'nose uppers', a complete waste of time, Link to comment Share on other sites More sharing options...
Jon H Posted November 1, 2022 Author Share Posted November 1, 2022 John S 1 - Yep, here we go again! John S - yea ok but how often do you loose a clunk really? I can think of only 1 time its happened to me in 30 years. Unless you take off vertically it wont matter anyway, at least not for a while. Ron - yea os do recommend it but its a small lift, 15 degrees and is used for setting the idle mixture on an air bleed carb. It not the full throttle nose vertical and shake the model like you are trying to kill it treatment normally connected with a nose up test. In any event, i have not seen or tried that procedure for setting air bleed carbs so its a new one on me. I just use the same method i do for twin needle carbs and its always worked fine. I wonder if they expect you to use pressure for that test. OS engines normally have pressure but older ones didnt have mufflers at all and the early 4 strokes just had a pipe. Still, air bleed carbs are more or less a dead technology now. Do any modern engines use them? Link to comment Share on other sites More sharing options...
J D 8 Posted November 1, 2022 Share Posted November 1, 2022 My PAW diesels have air bleed carbs. Link to comment Share on other sites More sharing options...
Chris Walby Posted November 1, 2022 Share Posted November 1, 2022 Oh no I have been doing it all wrong for the last 6 years with my non Laser engines! As I never do a nose up test on the Lasers I completely forgot to do it with my OS 2 strokes, strange I don't get many engine problems with them. Perhaps I need to fiddle with them more, but I prefer the turn up, tune and fly approach Jon advocates. Then again if I put the tank in the wrong position, forget to install the clunk and have a few leaks here and there I could make them unreliable.🤣 Link to comment Share on other sites More sharing options...
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