New Laser engines. What do you want?

[Don Fry]

John. You are right.

Jon you are right. But don't get upset, obsessive compulsive is a great virtue in an engineer. How else do we advance. Mind, small halo glinting, I have leaned my motors, taken more care to cool. And I would say, I am not regretting the moves.

[john stones 1 - Moderator]

I never said anyone had O.C.D. I said some like twiddling and some of them are a lost cause/enjoy it, I'm with you lads, best place for an engine is pulling your model in the sky.

[Martin Harris - Moderator]

Something we can all agree with!

[Jon H]

Posted by john stones 1 on 08/12/2017 18:06:10:

I see folk with all brands of engines, they fiddle no matter what, I see lads with tachos obsessing over a particular number, they take off...it cuts...but they still obsess over this number...take off again it cuts...oooh there's sumat wrong with my engine...nope there's sumat wrong with you.

Oh yes. I have seen many who will twiddle and twiddle. If i tell them it should do say 8500 on a given prop they want 8501 and 8499 is just not good enough. 'just fly it' i tell them, alas they fiddle.

hands up those who have set up a troublesome engine from a club mate and told them not to touch it, only to see them a few moments later screw driver in hand. both my arms are up its happened so often!

A tacho is a useful tool, but its not a tuning tool. I use it to check performance over time, and see if an engine is in the ballpark of its known performance.

I had a customer recently who returned a 180 for service. It was about 10-15 years old and used to throw 18x8 classic master props at 7500 but had slowed to 6800. Clearly a sign of an issue. The fault was traced to carbon build up in the exhaust. I also replaced a bearing and, most unusually, replaced the piston as i found some small cracks on inspection. Given the overall condition of the engine it looks like its got hot a few times, and with the carbon in the exhaust it would have been working hard which probably set it up to knock a little. Even a laser wont tolerate that sort of thing for long and the cracks were well established so i think it had been suffering a little while. Its no criticism of the chap who owned it, when a change is gradual its not easy to spot.

In any case, it was fixed and returned 7400 on the test run which is where its supposed to be.

Oh and i 'told him off' for using castor in the first place

[Tony Richardson]

Have to agree Jon I hate castor it’s carbon is really hard, being almost deaf I have to use a tachometer to get close after that it’s fly it and damn the torpedoes, I can usually tell wether it’s rich or lean by the way it responds to throttle inputs, also a good indication and one that has worked for me over the years is to set your high end and for the low end with engine at idle pinch the fuel line it should rise in rpm but a hair before stopping if it gathers a lot of rpm it is too rich if none at all it is way lean, you may or may not agree but works for me.

[Martin McIntosh]

Wow, I could really go to town on some of the posts today but I shall try to moderate it a little.

Firstly I regard the nose up test to be mandatory because a) it will show up a too lean mixture, b) a stuck clunk c( an incorrectly positioned tank. This applies much more to a 2 stroke motor. I have seen many rather elderly motors which benefit from a slightly rich mix continue to perform reasonably due to the excess oil.

4 strokes seem to perform much better with a less than ideal tank position, please see my pics on Cymaz` Stampe thread which show a dual tank installation for the Laser 155. Theoretically it should not work and should siphon fuel when not running but with the throttle closed it does not. Upright or inverted flight makes no difference.

All of my Lasers are inverted with the tank much higher than the carb and I have had no problems.

I too hate it when people insist on fiddling with the needle before every flight. Why do they do it? You don`t adjust your car tuning (carb types) every day do you? Other than a large change in weather conditions on the day you should never need to touch it. I operate a few highly strung 2 strokes on a pressure system and tuned pipes but once set, I leave them alone.

[Ron Gray]

Sorry Martin but I really do not follow your logic and that of the established method of nose up! The engine transition from low to high revs shows if an engine’s mixture is ‘close’ as does pinching the fuel line, if you can get to it. But nothing beats flying, if you can have a steady top end on the deck as Jon states earlier, then get it in the air. A stuck clunk is much easier to detect by shaking the model without the engine running and a lot safer. How can pointing the nose up tell you about an incorrectly positioned tank, incorect position is surely the horizontal relationship between the tank and the carb. An example of the latter was a colleague who could not start his ‘plane unless it was upside down (inverted engine) as when it was upright, the engine just flooded. Once started he went through the nose up test which saw no difference in the running of the engine. However it was obvious that the tank was about an inch too high (hence flooding when upright) and this showed itself when flying inverted for any length of time as the engine struggled to draw sufficient fuel as the tank was now too low (of course this isn’t a problem for a Laser as that will drag fuel from a foot below its carb!).

Again referring back to Jon’s comments, the danger is that the nose up test is taken as the be all and end all of all tests, whereas, in my opinion, it has very limited benefits. Things do change and move as technology and understanding advances, I believe this is one of those things and can be put alongside the belief that castor based fuel is the dog’s danglies rather than the potential engine destroyer it really is.

Having now launched the grenade, I’ll retire a safe distance whilst it all kicks off.

[bert baker]

Not see Steve Carr do nose up test before flying with his Tri plane

[Martin McIntosh]

Boxing gloves on then. Brass fuel tubes inside the tank bung will rot in time, especially if using nitro. Nose up for several seconds will show this up. What if the fuel line has a hole next to the pipe in the tank? Very common, especially with novices who do not round off the ends of the tubes `because nobody told me that I have to`. Also leaning out a motor (Lasers excepted of course) to the extreme will do it no good whatsoever and can cause a lean run or cut especially if it has a large bore carb. 56 years of running model engines has taught me quite a bit.

[Martin Harris - Moderator]

Posted by bert baker on 08/12/2017 22:52:15:

Not see Steve Carr do nose up test before flying with his Tri plane

You won't see me doing a nose up with a pumped petrol engine in a large model either. However, it would have saved several deadstick landings by the purchaser of a second hand model at my club recently who found the clunk pipe in the bottom of the tank upon investigation.

[Ron Gray]

Boxing gloves? Not at all, just differences of opinion and trying to see where the ‘scientific’ evidence is behind the nose up myth!

Rotted brass fuel pipes, fuel sloshing around in the bottom of the plane. Hole in the tube inside the tank, well if your tank is full nose up won’t show that, far better to fill ⅓ full and run engine on the deck. Leaning out motors, it’s not just Laser who recommend doing that, Weston UK, to name but one other, say exactly the same. As long as you have it running steadily without faltering why would you get a lean run / cut?

I bow to your superior length of time in the sport and the vast knowledge that has accumulated, far greater than mine but when I hear manufacturers stating things, and lets face it that’s all they are dealing with day in day out and their livelihood hood depends on it, I tend to listen and look st the facts, which, in my opinion in the nose up scenario, just don’t stack up.

Maybe a new ‘to nose up or not’ thread should be started as this one is about new Laser engines and seems to have got ambushed!

[Stephen Smith 14]

45 degrees should work for everyone neither up or down.

[Ron Gray]

Nice one Stephen, a compromise, that’s what we like. Still concerned with some of the older (and maybe not so old) fraternity wafting a rapidly rotating sickle around in the air though!

Trouble is, it doesn’t help that the BMFA handbook says to do the nose up test, therefore taken by some to be gospel.

Edited By Ron Gray on 09/12/2017 11:49:41

[Steve Hargreaves - Moderator]

Posted by Ron Gray on 09/12/2017 07:49:22:

Maybe a new ‘to nose up or not’ thread should be started as this one is about new Laser engines and seems to have got ambushed!

Indeed....I think we should agree to disagree & let it rest.

[Ron Gray]

[Jon H]

yikes. I thought we were done as well but I guess not.

I don't want to have to post this as its likely to start the debate again, but guys seriously, the nose up test will not show tuning errors and continually saying it will is not going to change the fact that it wont. I know many of you have significant experience and I am not trying to belittle that, but I work with these things every day. Trust me, its not helping you, at least when used exclusively.

So, before the thread gets locked I will boil the whole thing down to the following guide to tuning:

Laser engines do not recommend the nose up test as it is an unreliable guide to the state of tune of an engine. Differences in airflow and engine load in the air will require a different tune to those experienced on the ground in a condition that is unrepresentative of anything the model will see in flight. Often this will lead to an excessively rich mixture that can have a detrimental effect on the engines performance and leave unburnt fuel in the crankcase which will contribute to bottom end corrosion. While it is true that damaged plumbing can be detected with this test, it is likely that issues like corroded pipes will be detected through standard maintenance before becoming severe enough to be detected by the test.

It is the recommendation of Laser engines that all engines be tuned by ear for maximum rpm and that the tune is verified by a full throttle test of approx. 15 seconds. If the engine maintains a steady rpm for the duration of the test the engine can be considered adequately tuned. Fine tuning must then be done with the model in flight. It is recommended that a first takeoff of a new model without any flight testing is done at 75% throttle as a precaution.

If the engine overheats and looses power in flight the model should be landed and the engine allowed to cool before restarting. No changes should be made to the needles and the fuel tank should not be refilled. If the engine returns to full power then cooling is insufficient and the engine just overheated. if however it is lean and wont return to full power do not adjust the needle, refill the tank, restart the engine and test again. If the engine now runs as before the tank is too high and needs to be lowered as it has leaned off due to the change in fuel head. If the engine refuses to return to full power under any condition without retuning it is likely some debris has become lodged in the needle and the carb needs to be cleaned.

Other running issues will need to be considered on a case by case basis.





So, thank you all for your input. I hope nobody feels put out or vilified as that was not my intent. Clearly this is still a hot topic but my recommendations as a manufacturer are as above.

Keep 'em flying guys.

[Martin Harris - Moderator]

As I seem to have triggered this debate, perhaps I can give some conclusions - especially in the light of some more experimentation today.

First though, let me state that I don't disagree with virtually anything that Jon has stated above. Today's testing has confirmed my expectation that mounting the Laser sidewinder style has cured the erratic mixture completely - no more going lean in the vertical while going rich in the dive and perfect behaviour in all attitudes.

So, yes - the nose up test was irrelevant in this case, would prove nothing and level tuning provided a correctly running engine throughout the flight.

But, and this is the only respect in which I disagree, I will still be doing a nose up before the first flight of the day with any model that I feel I can do one safely with. Having agreed that Jon is correct with his tuning advice, why would I take this seemingly contrary and illogical approach? Well, being not of the needle twiddling fraternity, my normal practice is to start an engine, power check it and fly. In 99% of cases this works perfectly but the nose up just gives me extra confidence that I haven't knocked the needle just a fraction lean (hidden by a full tank's head of fuel perhaps), flipped the clunk pipe, developed a leak etc. Models that I'm asked to test fly may have less than optimal installations and I want to ensure that the first flight isn't compromised by installation problems, Others, which are not safe/practical to check nose up such as my 1/4 scale Cub, are flown with caution as per Jon's method and I'm prepared to do an in-flight tuning check and landing for any adjustment on the day.

The safety aspect may be a grey area. I would contend that I do it in a safe manner and as an instructor and club safety officer, train, encourage and advise others to do so too. I do not - and would not - advocate the propeller being in line with anyone's head - it should always be possible to remain behind the "burst plane" and see no undue hazard when performed correctly. Others with differing pits layouts and practices (and I've seen a few that have made me cringe!) may see this differently.

Maybe there has been enough reasoned debate for people to adopt or adapt practices in the light of the thoughts expressed by the participants?

[Jon H]

Sounds fair Martin.

And for what its worth, while its time to call time on this topic for now, we all managed a civilised debate without it becoming an argument which is a win.

Good to hear the 62 is happier now, did you try the 12x6?

[bert baker]

Just a well no one mentioned the nose down test,

Whilst you were wearing your fingers out typing I went flying today.

I did watch a Lazer 180 fly a model today

[Martin Harris - Moderator]

Yes I did. A little better although I think I'll be dropping the original engine back in now that the experiment has concluded - thanks!

I'll put the 62 into something slightly smaller or more sedate when the right home comes along.

P.S. I see why you redesigned the silencer fixing - although happily, I saw it fall off and we found it OK

[Martin Harris - Moderator]

Posted by bert baker on 09/12/2017 17:32:17:

Just a well no one mentioned the nose down test,

Whilst you were wearing your fingers out typing I went flying today.

I did watch a Lazer 180 fly a model today

Who said I wasn't flying it today? I came home to do my typing when it got dark!

Edited By Martin Harris on 09/12/2017 17:38:11

[Jon H]

Posted by Martin Harris on 09/12/2017 17:35:09:

P.S. I see why you redesigned the silencer fixing - although happily, I saw it fall off and we found it OK

Yea the grub screws were pants. just glue the thing in with epoxy. If you ever have to get it out just hit it with a blow lamp.

I know its crude, but it gets the job done

[Jon H]

I received a pm asking about the progress of the laser petrol engine and thought it best to update everyone.

Currently I am working on it but its somewhat in the background. As many will have noticed we don't have a great deal of stock at the moment and whenever I list new stock it sells out in a matter of hours. We need to make more engines and make them faster. Its a continued frustration of mine that we cannot keep the engines in stock and there have been some 'discussions' behind the scenes as to why its taking so long to sort it out. In essence, we are looking at a complete restructure and totally new way of working to meet the demands of the hobby in 2018. Things have changed a great deal since laser started and we have not kept up as well as we could have. The engines we are making now are the best we have ever made, our prices are good, and I like to think we hit the nail on the head with service most of the time. We just need to make more!

So, getting enough glow engines built to satisfy the demand is taking most of my time at the moment.

Development is continuing though with prototype petrol 155's, 180's, a 300 and 360 under way. The 155's are being assembled at the special request of 2 chaps. I have never built a 155 petrol before and will only be building 3. One for me, one for each of those two guys. I cannot guarantee that it will make it as a production engine given how expensive it would be. If you think £450 is a fair price in the current market for a 26cc 4 stroke petrol, and you think its an engine you would want, let me know. If you guys all want one, ill convince my boss to make the parts.

The 300 and 360 will be one off's for factory testing. Once then 180 is sorted they are the next target.

The 180's are the pre production batch I have mentioned before. I have some names of guys who have stepped up and are willing to help us out with some testing. These chaps are buying the engines (at discount) so I very much appreciate their willingness to help with the development of the engine. I think I have 3 confirmed names and should have 5 engines available. if anyone is interested let me know.

The engines will be close to production spec with only detail changes possible later. if testing reveals these changes are not necessary then we wont change a thing.

Currently I have the new backplates needed for the petrol engines ready to go. We are now trying to streamline the manufacture of the pump so it is easier to make and not a prototype. This has proven more of a challenge than originally though and entails a slight redesign to the way the pump is built. Its functionality is the same as before.

Next on the agenda is the new carburettor body and new needles. The engine needs different slow and main needles so they need to have their final specs nailed down and they need to be made. The carb body is up soon as the glow carb bodies are running low and they will run together on the machine. Once the design of the choke is nailed down we can get the body into production. I have also drawn up the production spec pressure regulator in CAD and that is ready for manufacture and its required spring has been ordered as well.

A great deal of the work has been delayed by unexpected pressures on the manufacturing side of the business and preparations for our upcoming factory move. I am still targeting a spring release though so fingers crossed everything runs well over the winter with the test engines. The prototype in my stampe has been pretty much faultless and does a great job hauling the model around and didn't seem to mind the cold when I flew it the other day.

So that's the state of play at the moment. its frustrating its taking so long but it is what it is. I'm keeping the pressure up, I'm just at the mercy of the manufacturing side.

[Steve Hargreaves - Moderator]

Post deleted.....the nose up debate is closed.

[Aldo Rebsamen]

Hello Jon,

earlier in this thread there was some discussion about larger mufflers. Since we also have noise problems, I would love to see some way to reduce noise. Do you have some bigger mufflers in the pipeline, or does it not help? Running older 150, 200v and 360v.

Thanks for doing these great engines, Aldo