New Laser engines. What do you want?

[Former Member]

[This posting has been removed]

[Jon H]

Martin, we have never had a big problem with this before and I have to say I have never noticed it on my own models. Noise testing from the front of the model is also pointless anyway as the stalled prop makes most of the noise. This noise will not be present when flying.

That aside though, if we mod the exhaust it wont fit for someone else and so they will ask for a mod. We will end up running in circles forever. I would also suggest that the louder noise from the long outlet exhaust is more likely to be caused by its smaller dia outlet pipe vs the standard affair. Any engine over about a 120 will cremate any silicone extension and frankly the 16x8 is a shade small for the 155. 17x8 would be a better bet. If noise is a super serious problem I will have a secondary exhaust available at some point. I have the parts made just no time to work with them.

So, the petrol engine...cant remember where we were with my last post but in essence I have given up on walbro carbs and am doing something different. The design is done and I need parts made. This has been the state of play for about 5 months now with zero progress made although an assorted number of prototype parts are set to be made quite soon.

The reason for this delay is that I am too busy with glow and diesel engine orders as well as a huge number of spares orders to dedicate any time to it so even if I did have the parts it would not be a priority at the moment as lead times are increasing already to a level that is not acceptable and I need to dedicate all of my time to getting them down.

As for the performance of the 180 petrol it is in a good position vs its competition but it is simply not good enough to sell. The fact that it is better than an NGH38 is not enough. It needs to be as good as a Laser and at the moment it is not consistent enough. The fact that it worked perfectly in my wot 4 but stopped in my stampe causing serious damage to the model only went to prove that it was not ready. If anyone here has tried a saito FG30 in the H9 30cc spit they will understand what I mean.

I will get on to it, but I regret that with only 1 person working things take time, and with glow engine orders quite high clearly petrol is not a priority to everyone. In fact a large number of people ordering from us at the moment are moving back to glow after noise and reliability issues with petrol.

[Jon H]

Sorry martin I misread your post.

Without knowing how the thing is setup I cant quite understand that. Unless the longer outlet is deadening the sound. In any event 84 is really loud for a 155. My 155 prototype in a kit built P40 is only 78 at about 7m (didn't have a tape). it has a long outlet exh pointing down and a 17x8 apc prop. Fair enough I did test it with a noise meter app on my phone, but I don't think its going to be off by 6db!

[Martin Harris - Moderator]

It's a new meter which I've checked against an (admittedly out of current calibration) industrial standard calibrator and was spot on. The model (a fairly lightly built pattern ship which probably resonates more than a conventional kit build) sounded a bit rorty in the air and I'm sure that the noise was exhaust and not prop (loudest front on and exhaust side).I have to say that this combination seemed much louder than other Laser powered models at our field but it's the first 155 I've had dealings with. A larger diameter prop is not practical for the owner due to ground clearance issues and the close cowled installation prevents any change of silencer angle.

I'm fairly convinced that if the exhaust is being directed towards the prop then it interacts rather like a pusher does with airflow off a trailing edge - a small electric DH2 at our club sounds like a good 40 is powering it! Putting the shorter standard exhaust on it appears to correlate this by dropping a dB. You might be able to check this when you're next test running an engine with the long outlet? The difference with the 120 I mentioned earlier (which I think had a silicone extension that was similar in length to the long outlet) when angled slightly backwards was astonishing.

Edited By Martin Harris on 29/05/2016 16:51:15

[Jon H]

HI Martin

We do not have the facilities to test engines for noise as a concrete courtyard surrounded by buildings and a railway is far from ideal. It would also be futile as the model its nailed too makes such a huge difference. I tested the 155 in a wot4 xl and my P40 warhawk. Neither were very loud and the P40 itself was very quiet. We have not heard of anyone having specific issues with the 155 in terms of noise although we will be doing some work on the exhausts when time permits to see if we can get it a touch lower as some clubs have very draconian noise limits.

As for the specific issue you are having, if the model is a patternship then the 16x10 would be my choice of prop anyway. I assume its an apc and not some horrid master prop? I also assume the engine is fitted to a decent glass/nylon mount and not a super floppy one or anything metal. Clearly prop balance and all that stuff is important too.

If all of this has been done and its still not enough then you could try a flexi extension with one of the new inline exhausts I hope to get sorted in the near future. This will take the sound backwards and well away from the prop, although I do not think that is the issue. To discuss in greater detail give me a call on Tuesday and we can go through the options.

[Martin Harris - Moderator]

Hi Jon, it's no longer a problem as we got it down to 82dB - my suggestion was that you might like to see if you could hear a significant difference with a forward angled outlet pipe yourself, as it might help should any other customers encounter unusual difficulties...

Edited By Martin Harris on 30/05/2016 00:28:07

[Manish Chandrayan]

Hi Jon

Has the 150 been discontinued? I do not see the 150 on the website.

In case it has been discontinued how long can the current owners expect the engine to be supported in terms of spares etc?

[Jon H]

Hi Manish

Full details here http://www.modelflying.co.uk/forums/postings.asp?th=117859#2015533

Edited By Jon Harper - Laser Engines on 31/05/2016 16:35:25

[MattyB]

Posted by Jon Harper - Laser Engines on 29/05/2016 16:08:36:

...So, the petrol engine...cant remember where we were with my last post but in essence I have given up on walbro carbs and am doing something different. The design is done and I need parts made. This has been the state of play for about 5 months now with zero progress made although an assorted number of prototype parts are set to be made quite soon.

The reason for this delay is that I am too busy with glow and diesel engine orders as well as a huge number of spares orders to dedicate any time to it so even if I did have the parts it would not be a priority at the moment as lead times are increasing already to a level that is not acceptable and I need to dedicate all of my time to getting them down.

As for the performance of the 180 petrol it is in a good position vs its competition but it is simply not good enough to sell. The fact that it is better than an NGH38 is not enough. It needs to be as good as a Laser and at the moment it is not consistent enough. The fact that it worked perfectly in my wot 4 but stopped in my stampe causing serious damage to the model only went to prove that it was not ready. If anyone here has tried a saito FG30 in the H9 30cc spit they will understand what I mean.

I will get on to it, but I regret that with only 1 person working things take time, and with glow engine orders quite high clearly petrol is not a priority to everyone.

I am glad to hear there is still there is lots of demand for your existing products, but its a shame that is impinging on your ability to progress the new petrol engine(s). Time for an apprentice maybe? I believe there is a £1500 grant available from the government for each one taken on these days - might be worth considering.

Anyway, keep us updated with progress- I know many of us are eager to see the petrol variant progress and are intrigued by your alternative approach to the Walbro carb...

[Hangar 9 nut]

Went in to Laser engines today to pick up a prop driver for a Laser 70 and ended up having a long chat with John about Laser diesels hopefully they will do more but at the moment diesels are on hold !

[Jon H]

Hi Matty

We already have one apprentice in the workshop and while it sounds like a goo idea there are often challenges to go along with it.

Simple jobs like dealing with orders and packing them up would be a real help, but what I really need is someone who can do the slightly more advanced tasks. The snag is I don't have time to teach them and given that I am not in charge of who we hire I think I am on my own for a bit.

H9nut, good to see you. Interesting conversation and I will come up and fly with your guys at some point

[Martin McIntosh]

Sounds like there is a good job going for an engine guru!

Just removed the cowl from my Stampe to inspect the 155 since there was a bit of grey stuff in the oil residue and the motor was visibly moving after a flight but this was only due to the silencer, not the motor, being very slightly loose. I have the two part mount from Slough Models but I recall that there is a stiffer one available. Any idea exactly which one this is please Jon?

Martin

[Jon H]

We can supply a nice beefy mount. Give me a call tomorrow and we can sort it out

[Jon H]

I have a question for the masses

As part of an experiment into bore/stroke ratio combinations i have a prototype for a very long stroke 120 size engine. I think i have mentioned this before but not given a great deal of detail.

As this is a very long stroke engine it gives its best performance at lower rpm which makes is very quiet and very efficient in terms of its thrust output. Clearly an engine like this is probably best used in a scale model of some kind but there is no real reason why a sport model could not take advantage of the big prop.

To give and idea of performance these are some figures from testing:

15x8 apc @ 8000rpm (too small)
17x6 apc @ 7700rpm
17x8 apc @ 7200rpm
18x8 apc @ 6600rpm (calculated figure from other test results)
18x8 classic master @ 6300rpm
20x6 classic Master @ 6000rpm (and an 800rpm reliable idle!)
20x8 apc @ 5600rpm

Peak power comes at approx 7000rpm with the 17x8 and 18x8 apc (as calculated) coming very close to each other in terms of hp. That said, the 18x8 will out thrust the 17 and although some airspeed may be lost it still calculates out to about 50mph which is within the range required for a WWII fighter for example.

So, low idle, low noise, big props and nice easy starting. All sounds great right? Well there are some compromises. The main one is physical size/weight. The engine is basically the same physical size as our 180 but that still leaves it 3mm shorter than an OS120 surpass or ASP clone. Due to the large/heavy crank the weight of the engine is 1160g which is quite a bit for a 120, but how often to scale models end up nose heavy? It wouldnt bother me, but being that much more than other 120's some folk might be put off. This weight could probably be reduced a bit but for now it is what it is.

The only other 'issue' is throttle response. Personally, i dont consider it an issue, but as the engine is long stroke it takes a bit longer to accelerate than a snappy short stroke engine. Think harley vs suzuki. Worst case was when the heavy brick of a classic master 20x6 was fitted and accelerating from idle rpm (1500) to max rpm took perhaps 2.5 seconds? i didnt measure it but it was noticeably longer than a normal engine. My test was to idle the engine, stuff the throttle fully open and just wait for the rpm to pick up, and pick up it did with a very satisfying thhhrrrrruuubbb up to max rpm, it just took a little longer.

So, with all of that said and done who (if anyone) would be interested in an engine like that? Given that it is best suited to scale i do not see any of the 'problems' i mentioned above as actual problems and if people are interested i can shoot a video showing how the engine handles.

Please let me know your thoughts

[Martin Harris - Moderator]

Sounds very civilised and as you say, ideally suited to a warbird - and WW1 short nosed models? Response time shouldn't be a problem for scale flying - most large engined WW2 single seaters needed slow throttle opening at low airspeeds in order to prevent finding themselves inadvertently inverted...

Mention of Harleys prompts the question of whether you're considering a similar exercise for one or two of the twins?

[Terry Walters]

Sounds like that might do very nicely for the sort of models I tend to fly these days. Again a response time of 2.5 seconds from idle to full wouldn't worry me. If as you say it would be shorter than the OS FS120 that's a bonus too. (Would that include the height of the silencer pot?)

Low revs - large prop - all good.

Efficiency/thrust does that mean it should use less glow fuel? I'm one the guys who wouldn't change to petrol for fuel saving because I just prefer the sound of FS glow engines but if I can use less glow fuel that's fine for me.

Terry

[Jon H]

Hi Martin

The investigation was actually aimed at a future radial.

Before the thread goes into meltdown, please note that there is no plan to do a radial any time soon. I am just researching things so that i have the information in hand should the time come.

That said, a long stroke 240 twin would be a nice engine but it would be the same size as the 360v and produce less power than the physically smaller 300v while turning the same prop. However, if the nature of the power delivery is more important than the specific power output then it would be a lovely thing. If i get time/parts i might knock up a prototype to see where it is in terms of performance but i would estimate about 7200 on 20x8 and about 6500rpm on 21x8 (apc in both cases).

All that said, something like a 24x6 @ 6000 would work very well in a WWI type model and i think would be within the realms of what the engine could manage.

[Jon H]

Terry

not sure about fuel consumption as i didnt test it directly. But it used about 8oz through my test period earlier today. I ran 7 props for at least 2 minutes each alternating between full power and idle with very little mid range time. Either way thats about 15 mins on 8oz including the fuel wasted priming the cylinder when restarting.

Oh and while we are at it, the fuel was 5% nitro and 5% oil so its clean too!

Please dont try your own engines on 5% oil yet though, im still testing

[Terry Walters]

That's all sounds good to me Jon. You should be re-branding as Laser-Green engines! LOL!

[Martin McIntosh]

Still interested in a 300 single if it will turn a 23x8 @ 7000 or larger at same thrust, less revs.

[Jon H]

As I'm really nice I did a video for you guys. I am using the 20x6 as it shows the worse case in terms of rpm pick up as it weighs a metric ton. Please ignore the skip and piles of junk beind the bench, and the prop/camera frame rate also makes the engine all wavey at times, I assure you it is not that flexible in real life!

[Terry Walters]

Jon - that sounds very nice and the throttling up is fine - quite scale really! Well caught Sir with the tacho! Doesn't seem to be any real problem. Any vibration issues with the long stroke?

Terry

[Manish Chandrayan]

The prop shaft length looks like a bit on the shorter side. What with that large prop and thick hub. But lovely running engine there

[Jon H]

Posted by Terry Walters on 05/08/2016 19:34:03:

Jon - that sounds very nice and the throttling up is fine - quite scale really! Well caught Sir with the tacho! Doesn't seem to be any real problem. Any vibration issues with the long stroke?

Terry

Nope, the crank is that of our 180 and vibration is not an issue. Most of the noise is prop noise which you cant hear when behind it. The fact that you can hear the noise of the factory over the engine is also a sign that it is not very noisy and I really like the way it sounds. I could fit it to our wot4 xl and fly it....hmmmmm

Manish, we normally supply a sleeve nut with our 180 to get over the issue of a thick prop. In this instance the nut is fully threaded anyway so its not an issue.

[Jon H]

Posted by Martin McIntosh on 05/08/2016 19:01:43:

Still interested in a 300 single if it will turn a 23x8 @ 7000 or larger at same thrust, less revs.

I missed this one.

I doubt a 300 would take a 23x8 to 7k. The 360 takes 22x8 to 7k and that's a good chunk bigger. a DLE 55 two stroke will turn 23x8 menz props at 6500 so I think that is a big ask of a 4 stroke.

Clearly propeller brands play a huge part here. A menz would be much slower than an apc, but still I think its pushing it. But, I will see what I can do