Laser 180 Petrol

[Artto Ilmanen]

Posted by Jon Harper on 10/10/2014 12:42:08:

All the details I have so far are:

29cc capacity

Bronze bush big end

40:1 fuel mix

prototype running on walbro/tillotson carb but more development is to come as its not suitable for a model.

Fuel consumption approx. 12cc/minute when flying normally with 17x8 prop.

Props in the 17-22inch range

I have no details of running time (hours) but the engine has been run like this for over a year of testing without any mechanical distress.

So the prototype engine is mechanically the same as the glow version? i.e. you have just installed a different carb arrangement and the CDI?

Btw. I'm looking forward to seeing a flying video!

-Artto

[Jon H]

The engine is the same as the glow version mechanically, although a great many other things have been tested (cam timing, comp ratio etc etc) to see if any improvements could be found. This example is running slightly different valve timing to a standard 180 but the performance difference between the two is negligible.

the last flight I did included a bit of a stress test for the big end bearing and engine as a whole. Long story short, I left it at full throttle for a solid 10 minutes before getting bored of the fact that nothing was going wrong and so went back to flying more normally. This mirrored a 5 minute test I did on the bench which showed a heat build up and slight loss of performance after about 2 or 3 minutes flat out on the ground, the engine did continue to run though but lost about 300rpm by the end of the 5 minute test. The purpose of repeating the test was to see if the same problem existed in flight with proper cooling and even at double the duration the engine was perfectly happy so cooling is not an issue.

[Artto Ilmanen]

Posted by Jon Harper on 03/11/2014 11:33:17:

The engine is the same as the glow version mechanically, although a great many other things have been tested (cam timing, comp ratio etc etc) to see if any improvements could be found. This example is running slightly different valve timing to a standard 180 but the performance difference between the two is negligible.

the last flight I did included a bit of a stress test for the big end bearing and engine as a whole. Long story short, I left it at full throttle for a solid 10 minutes before getting bored of the fact that nothing was going wrong and so went back to flying more normally. This mirrored a 5 minute test I did on the bench which showed a heat build up and slight loss of performance after about 2 or 3 minutes flat out on the ground, the engine did continue to run though but lost about 300rpm by the end of the 5 minute test. The purpose of repeating the test was to see if the same problem existed in flight with proper cooling and even at double the duration the engine was perfectly happy so cooling is not an issue.

Hi Jon

Thanks for the update. It's very encouraging the big end bearing holds up well. It's very obvious that when running on petrol a special attention to cooling arrangement is needed no matter what make the engine is. I recall having read an article written by Pe Reivers on MVVS engine temperatures. The point of the article was that if no ducting / baffles are used a petrol engine is sure to overheat.

Also, from what I have read on petrol Saitos (FG-57TS, FG84R3, etc) the general consensus seems to be the baffling is of outmost importance to control operating temperatures.

Good luck with R&D and please be assured that there will be buyers of Laser petrol engines (myself included) once you feel ready to launch one.

I would love to see a Laser 310V / Laser 360V petrol. Maybe if you can sort out the challenges related to a compact & well performing carb small enough, then, a petrol V-twin could be developped. I guess the current line of V-twins feature the same big end bearing as the 180 single?

Further, both CH Ignitions & RCEXL have their versions for un-even twins. I think the lates Saito's use the RCEXL (rebadged to Saito).

-Artto

[Jon H]

I have a list entitled 'engines I want to make' and its as long as my arm. First things first, the 180 must be spot on and have all the questions answered before going further.

[Artto Ilmanen]

Posted by Jon Harper on 03/11/2014 15:26:43:

I have a list entitled 'engines I want to make' and its as long as my arm. First things first, the 180 must be spot on and have all the questions answered before going further.

I see, "first things first" as you say! No problem. In the meanwhile we V-twin users just enjoy our Lasers they way they are. Well, for the time being I'm waiting for the winter to arrive to be able to fly on skies. +10 degrees and lot's wind & humidity at the moment prevent's me flying.

[Martin Whybrow]

Posted by Artto Ilmanen on 03/11/2014 16:20:23:Well, for the time being I'm waiting for the winter to arrive to be able to fly on skies. +10 degrees and lot's wind & humidity at the moment prevent's me flying.

+10, that's warmer than the UK today! Just heard that my relatives went X country skiing for the first time this season at the weekend. Love Finland in the winter!

[Artto Ilmanen]

Posted by Martin Whybrow on 03/11/2014 20:08:42:

Posted by Artto Ilmanen on 03/11/2014 16:20:23:Well, for the time being I'm waiting for the winter to arrive to be able to fly on skies. +10 degrees and lot's wind & humidity at the moment prevent's me flying.

+10, that's warmer than the UK today! Just heard that my relatives went X country skiing for the first time this season at the weekend. Love Finland in the winter!

Thanks Martin for your kind words

By the way this climate change (or whatever its is?) brings us strange things..such as mild autumns and winters in Northern countries, such as Finland. Grass is still green, etc? I wonder if we get snow & frosen ground by Christmas which used to be the norm when I was a kid. Now we are happy if we get snow in the Christmas eve. I try to fly the model on wheels by mid December or something before fitting the skies on the model.

[andyh]

<bump>

just thought I'd bump this to see how it's getting on. a petrol 120 might just tempt me back to IC

[Jon H]

Apologies for the lack of updates. Things are very difficult at the moment for numerous reasons including a large upgrade to the factory.

Progress has been made with the carburettor but it is still not to an acceptable standard (at least not to me).

It is unlikely we will make a petrol engine as small as a 120 and are looking to a new range of larger engines for the future. But, in the short term the 180 is the main focus.

[Jon H]

The engine now has a new carb that I have modified to improve its performance. The results have been very good and I hope to start work on a pre production batch of 5 engines soon so we can do further testing.

[Frank Skilbeck]

[Martin Whybrow]

Looking forward to seeing the latest update; will it be at the May ModelAir weekend at Old Warden?

[Jon H]

Hi Martin

I am intending to head over there but am not sure at this point what models I will take as it depends on the weather and if I manage to get them all ready. If the planets align I might be able to get my 1/4 scale stampe ready in time and I hope to have one these pre production engines fitted to it.

If not then I can take the prototype along in our rather beaten wot4 xl. The model is far from pretty but it will show what the engine can do.

[Artto Ilmanen]

Great news, Jon!

I'm looking forward to a new video on the engine with the new carb set-up!

-Artto

[Martin McIntosh]

I was lucky enough to witness this motor being run recently on the actual prop from my 180 glow and was very impressed with the RPM figure which was higher.

[Chris Berry]

Currently looking for a petrol engine for my Wot4 XL so a 180 would be perfect! Will follow with interest! If its as good as the glow versions then you're on to a winner Jon!

Edited By Chris Berry on 06/05/2015 20:52:15

Edited By Chris Berry on 06/05/2015 20:53:29

[Martin Harris - Moderator]

Posted by Martin McIntosh on 06/05/2015 20:42:12:

I was lucky enough to witness this motor being run recently on the actual prop from my 180 glow and was very impressed with the RPM figure which was higher.

That's interesting as the glow should theoretically produce considerably more power than a petrol equivalent. Were you comparing Jon's engine with another Laser or a different make?

I wonder whether this due to inefficiency in the glow carburation, glow ignition characteristics or greater efficiency with a lower oil content?

[Jon H]

So far the performance figures for the petrol version match the glow engine almost exactly. The petrol engine is better on the bigger props though as it dosent load up like a glow engine does.

There are reasons for the constant power output of the two engines. One of them is that we don't run high nitro in our engines and so we have less to loose from the point view of the 'fuel power'. Also with the cdi we can optimise the ignition point which helps with performance. Other factors like combustion chamber and comp ratios play a part as well. I have also been working on the carb extensively so that I can use one which is large enough to give us the power we need but not so small as to rob performance. If I just wanted the engine to work but was happy with reduced performance it would have been ready over a year ago, but giving away 600rpm was unacceptable.

The most recent rpm numbers are 7400 on 18x8 menz, 6700 on 19x8 menz and 6800 on a 20x6 turnigy...thing. Martin told me that the prop he gave me was an 18x8 of some kind. It did 8000rpm and to my eye looked more like an 18x6 but appearances can be deceiving. At any rate the laser ran that prop 1000rpm faster than the NGH38 that it came off.

Chris, in all honesty I would think again about using the 180 in the wot4. Because the model is designed around a smaller engine the weight of the 180 and the large amount of lead on the tail to balance it do turn the model into a bit of a brick. The performance is totally unlimited still because of all the power available, but its not as good as it was with the 155 prototype and no lead which powered it before.

If you had a 70-75 inch extra or yak, or perhaps the xl acro wot/wots wot as they have shorter noses it would be ok. It would also be great in (for example) that 30cc hangar 9 spitfire, but for the wot4 its just too big. As much as I would love to sell you one I am also a modeller, and I wouldn't want to sell you the wrong thing for your model.

[Don Fry]

Jon, my Visa twitches. The God speaks. Does this thing run smooth like a laser.

[Jon H]

watch the video **LINK**

Since then I have made a number of changes and would say its better now because its more stable on a range of props.

I would probably say that overall it is smoother than the glow version over most of the rpm range and just as good the rest of the time.

[Martin McIntosh]

Martin H., it was from my Laser 180. I must admit that I have not had any reason to tach it recently. It is certainly an 18x8 (Mezlik I think) because I have a few of them and all perform the same. The petrol version RPM was at least on par.

[Chris Berry]

Hi Jon, yes it probably is a little on the big side for the Wotty XL. I am looking at the new Acro Wot so that could be an option. A chap in our club has an ASP 120 in his and it can be virtually hand launched on a clam day.

Cheers

[Jon H]

Hi Chris

I checked out the big acrowot in a little more detail and I think the 180 will be ideal as its almost 80 inches span so the additional weight compared to a 120 fs will be no bother at all. With a projected flying weight of 14lbs the model should go like a scalded cat.

One other thing I forgot to mention was that i got a friend, who is experienced flying 4 strokes, to fly our 180 equipped wotty to see what he thought of the handling of the engine, its response and performance. As i have used the engine from day one and am used to it i wanted to see how someone without that experience and a different flying style would perceive the engine so i can get an idea of what to expect from customers who could be using their first petrol 4 stroke.

His main comment was one of surprise at the power of the engine but only after commenting to me that he felt he didn't have much power. The context of the comment was that he was flying in level flight at about 1/2 throttle and opened up to full chat for a loop. I asked why he didn't leave it at 1/2 throttle for the loop and he commented that it would have never made it round at that low power setting. This was when i challenged him to pull the nose vertical from level flight and see how far the model got at only 1/2 throttle. He was very surprised as it headed for the heavens for a long while before it eventually ran out of puff.

After much conversation it came about that he was judging the power of the engine from the exhaust note, which in the case of the fairly slow revving 180 is quite soft when running on petrol and while he loved the sound, he said it misled him as to the amount of power he thought he had available to him. Once used to the sound of the engine he said the sheer grunt of the engine was a real surprise and the power delivery was a little less peaky than his glow 4 strokes so more power was available through the whole range of the throttle. The fact that the power was delivered as thrust and not so much as speed was also something he was not used to as high power normally means high speed. This was partly due to the way the 180 works and also in part due to the 18x8 prop. Flat out it still has enough speed to worry me about pulling the rudder off!

If it can be arranged within the rules of the event at old warden anyone there is welcome to fly the model and iwould be interested to hear comments. If flying is not possible, i would still be interested in any comments about the engine and its performance either in person at the show or here on the forum.

Edited By Jon Harper on 07/05/2015 10:55:01

[Artto Ilmanen]

Posted by Jon Harper on 07/05/2015 10:52:22:

Hi Chris

I checked out the big acrowot in a little more detail and I think the 180 will be ideal as its almost 80 inches span so the additional weight compared to a 120 fs will be no bother at all. With a projected flying weight of 14lbs the model should go like a scalded cat.

One other thing I forgot to mention was that i got a friend, who is experienced flying 4 strokes, to fly our 180 equipped wotty to see what he thought of the handling of the engine, its response and performance. As i have used the engine from day one and am used to it i wanted to see how someone without that experience and a different flying style would perceive the engine so i can get an idea of what to expect from customers who could be using their first petrol 4 stroke.

His main comment was one of surprise at the power of the engine but only after commenting to me that he felt he didn't have much power. The context of the comment was that he was flying in level flight at about 1/2 throttle and opened up to full chat for a loop. I asked why he didn't leave it at 1/2 throttle for the loop and he commented that it would have never made it round at that low power setting. This was when i challenged him to pull the nose vertical from level flight and see how far the model got at only 1/2 throttle. He was very surprised as it headed for the heavens for a long while before it eventually ran out of puff.

After much conversation it came about that he was judging the power of the engine from the exhaust note, which in the case of the fairly slow revving 180 is quite soft when running on petrol and while he loved the sound, he said it misled him as to the amount of power he thought he had available to him. Once used to the sound of the engine he said the sheer grunt of the engine was a real surprise and the power delivery was a little less peaky than his glow 4 strokes so more power was available through the whole range of the throttle. The fact that the power was delivered as thrust and not so much as speed was also something he was not used to as high power normally means high speed. This was partly due to the way the 180 works and also in part due to the 18x8 prop. Flat out it still has enough speed to worry me about pulling the rudder off!

If it can be arranged within the rules of the event at old warden anyone there is welcome to fly the model and iwould be interested to hear comments. If flying is not possible, i would still be interested in any comments about the engine and its performance either in person at the show or here on the forum.

Edited By Jon Harper on 07/05/2015 10:55:01

I Sure wish I could join the event. This being inpossible I hope to see lot's of pictures & videos on the model!

Artto

[Jon H]

For those who would like to see the engine in action I will be flying at old warden on Saturday. As the stampe is not ready it will be the beaten and battered wot4xl showing what it can do.