New Laser engines. What do you want?

[Manish Chandrayan]

Ron

What you say is right with the tank moving, but by the same explanation, with the tube curving around can also lead to tubing getting kinked/pinched and shut off fuel supply to the carb if the tank moved.

Barbs on fuel lines are good idea to prevent slippage and securing the tank is even better

Let's see how many others want to see this change

[Don Fry]

I reckon a rear facing nipple would cause more complaints than praise, the forward loop gives choice as to where the pipe leads when you make the loop. A planning thing you get on every installation. A rear facing nipple tends to constrain where the pipe goes, and there may not be much space to the rear of the carb. But hay hoh, this is a problem I never knew existed.

[Former Member]

[This posting has been removed]

[Jon H]

Hi Tom

In many respects that is true, currently the engines work well so there is no need to reinvent the wheel so to speak. I know i have spend quite a bit of time talking about what we wont do, but i have tried to explain why as alot of ideas sound great in principal, but can have unforeseen consequences so we have to really examine the whole thing.

But, we are looking to move forward with new things and ideas, so some good news for you all is that we are targeting march/april time for getting the 30cc petrol engine into production. It is a tall order as it looks like i might have to design/build/test a whole new carb/pump/regulator before then, but that is the master plan. I have also finished the CAD drawings for another totally new design and the first prototype parts are starting to come through.

I will post more details when i can.

Edited By Jon Harper - Laser Engines on 07/01/2016 08:58:38

[Alan Hilton]

Hi Jon

Regarding oil and nitro content .Is synthetic two stroke oil suitable for use with methanol fuels? .I have several Lasers and have run them successfully on Duraglow for many years ,but am now finding it difficult to obtain this locally. I may be able to get methanol and I use racing 2 stroke oil in my petrol engines. I have tended to use 5 or 10% nitro content ,can I do without this ? Your posted about doing mail order fuel is very interesting I would be a customer

Regards Alan

[Frank Skilbeck]

Alan, probably not as it's designed to "dissolve" in petrol and may not mix with methanol so it will separate out. You can buy synthetic oil specifically for model glow engines, e.g. Southern Modelcraft will sell you ML70 and Model Technics have a range of glow fuel specific oils too

[Jon H]

Frank has nailed it

Have a chat with model technics or SMC or places like that. Grab ML70 or Klotz oil and go from there. 5% nitro and 10-15% oil.

I am also pleased to hear you cant get duraglo, its an awful fuel in modern engines. It was great in its day, but all of that castor does nothing other than make a mess

[Manish Chandrayan]

Which of the Klotz would you recommend Jon? KL 100 or the KL 200?

Edited By Manish Chandrayan on 07/01/2016 18:50:25

[Jon H]

Whichever one is also known as 'techniplate'. I have never dealt with the klotz oils when named just by their number. In truth, any decent oil that will mix with methanol should be fine

[Artto Ilmanen]

Posted by Jon Harper - Laser Engines on 07/01/2016 18:58:31:

Whichever one is also known as 'techniplate'. I have never dealt with the klotz oils when named just by their number. In truth, any decent oil that will mix with methanol should be fine

I may say a word here: Some of the Klotz oils are low visocsity oils such as Klotz Heliglow. I think one should avoid the low viscosity oils with Lasers, especially if 10% oil in the fuel mix is applied.

-Artto

[Jon H]

Agreed, low visc oil is not something I would recommend

[Artto Ilmanen]

Regarding the oils:

Some of the fellow modellers have been using Aerosynth 3 with Lasers. Aerosynth 3, being an easter based oil, is said to have superior abilities to tolerate high temperatures, too. While Fuchs Aerosynth 3 is widely available in continental Europe i'm not sure how available it is in the UK, though.

[Alan Hilton]

Re oil let me worry about solubility I'm a chemist an ester type synth stands a good chance of dissolving in methanol .Its the lubricating properties I'm interested
In

[Frank Skilbeck]

Posted by Alan Hilton on 13/01/2016 08:17:48:
Re oil let me worry about solubility I'm a chemist an ester type synth stands a good chance of dissolving in methanol .Its the lubricating properties I'm interested
In

On that basis they may work, but a normal full size two stroke will have ball/needle big and little end bearings, and so need very little oil, a model engine (two or four stroke) uses plain bushed bearings, and it's not clear how well an oil designed for a ball bearing engine would hold up in a plain bearing application. The model engine oils have been tested in this application but you might be the guinea pig with the racing two stroke oil.

[Artto Ilmanen]

Posted by Alan Hilton on 13/01/2016 08:17:48:
Re oil let me worry about solubility I'm a chemist an ester type synth stands a good chance of dissolving in methanol .Its the lubricating properties I'm interested
In

Alan,

Fuchs Aerosave / Aerosynth 3 have very good lubrication properties. I'm not a salesman of Fuchs products but a modeller. Here is a link of Aerosynth 3

http://www.aerosynth.de/pages/main.html

But anyways, to each his own choice

-Artto

[Jon H]

I have not attempted to mix synthetic two stroke oil with methanol but had thought about it. Its on my long list of things to try.

As for ball/needle bearings vs bushes, our 180 petrol prototype has a bushed big end on the conrod and runs at 50:1 with normal two stroke oil. It also runs like this with whatever oil is in the aspen premixed fuel. After chewing through about 10 litres of the aspen (approx 14 hours running) there is no wear at all on the big end or crank pin. The latter has in fact been polished to and almost chrome finish actually which looks ace! I checked out the rest of the engine and almost blinded myself when i held the liner up to the sunlight as it too was polished and shiny.

When i took the engine apart i was actually astonished as it was probably the cleanest engine i have ever seen internally. The aspen fuel had also removed some of the carbon deposits from its previous running on normal pump petrol.

Testing our glow engines on lower oil is continuing. My Laser 100 is still running happily on 5% ML70 oil and has got through over half a gallon. i DO NOT recommend people copy my experiment yet as we wont cover any damages to the engine if it all goes wrong, but so far testing seems to suggest oil could be dropped safely to 5% but we are not recommending it yet as more testing is required.

[Jon H]

I had the chance today to try out a 240v converted to petrol by a customer in Sweden. He has got a single carb behind the engine and has machined up a significant number of parts to make it all work (see below)

Now the engine does run and idles well but no better than the glow version. At full power it is about 800rpm slower than it should be and more or less matches a 160v running on glow fuel.

The mid range is not very smooth and the engine tends to pulse as the left cylinder misfires due to running a bit too rich and this cannot be fixed with the single carb setup. As a result the whole thing is no good for actually flying a model.

It is unfortunate the engine is not running better as a lot of good work has been done to come up with a neat and tidy installation, even though the engine is much heavier and longer than it was before (still shorter than an FG36 though).

Anyway, I thought you guys might like to see the sort of efforts people are putting into conversions only to end up with something that still does not work that well. That said, this solution is the best one I have tested and some mod might allow the engine to perform better but it would require significant work

[Roy Hill 3]

Hi Jon, I have found this thread to be very interesting, indeed, but what if anything is, or has been done, to create an efficient silencing system. If there is something in the thread on the subject I've missed it! I have an Evolution 20cc (Whoops! perhaps I shouldn't have written that!) for which I have had to have an silencer custom made as the one included is little more than useless.

[Artto Ilmanen]

Posted by Jon Harper - Laser Engines on 13/01/2016 16:08:13:

I had the chance today to try out a 240v converted to petrol by a customer in Sweden. He has got a single carb behind the engine and has machined up a significant number of parts to make it all work (see below)

Now the engine does run and idles well but no better than the glow version. At full power it is about 800rpm slower than it should be and more or less matches a 160v running on glow fuel.

The mid range is not very smooth and the engine tends to pulse as the left cylinder misfires due to running a bit too rich and this cannot be fixed with the single carb setup. As a result the whole thing is no good for actually flying a model.

It is unfortunate the engine is not running better as a lot of good work has been done to come up with a neat and tidy installation, even though the engine is much heavier and longer than it was before (still shorter than an FG36 though).

Anyway, I thought you guys might like to see the sort of efforts people are putting into conversions only to end up with something that still does not work that well. That said, this solution is the best one I have tested and some mod might allow the engine to perform better but it would require significant work

To sum up: we are looking forward to hearing of a better twin carburetter solution once such a thing is introduced by Laser Engines 😀

[Artto Ilmanen]

Posted by Roy Hill 3 on 13/01/2016 20:09:13:

Hi Jon, I have found this thread to be very interesting, indeed, but what if anything is, or has been done, to create an efficient silencing system. If there is something in the thread on the subject I've missed it! I have an Evolution 20cc (Whoops! perhaps I shouldn't have written that!) for which I have had to have an silencer custom made as the one included is little more than useless.

I too would be happy to hear of a thread dealing with the topic " designing principles of 4-stroke Rc engine silencer" or something similar.

[Jon H]

Hi Roy

Silencing has come up a few times and all i can say at the moment is that our petrol engine is no louder than the glow version. In fact when in flight they seem very quiet at part throttle and have a slight crackle at high power than the glow engine lacks. All in all however there is nothing between them in terms of overall noise (to the ear anyway).

That said, we are starting to hear comments from people that our current silencer is not enough as certain clubs clamp down on noise even further. We are investigating a new exhaust but it will take time to sort out.

[MattyB]

IMO the gap in the market is for effective silencing solutions for the increasingly common petrol two strokes of 20-50CC, not four strokes - in most (though not all) situations even the larger glow and petrol four strokes are quiet enough to meet the noise target at most sites. I agree this could change in future though as ever more restrictions are placed on clubs from grumpy neighbours and new developments.

Edited By MattyB on 14/01/2016 12:47:13

[Jon H]

Hi Matty

You are quite right, but unfortunately there is no definition between the types of engine. All electric is seen as quiet and friendly and IC is seen as one noisy lump when it is not at all the case. 4 strokes, and even correctly silenced two strokes can be very unobtrusive where as an EDF or combat wing on electric can be very irritating.

Another issue is differences in the way clubs do noise tests. Many (incorrectly) use the peak sound value which is not a fair representation as wind or other external noises can bump up this reading. Readings taken from the front are also meaningless as the stalled propeller causes almost all of the noise and this noise disappears in flight as the prop is no longer thrashing around without going anywhere. I have been meaning to ask the BMFA if they have a recommended test procedure as i cant find one online

[Martin McIntosh]

I think that I have posted this elsewhere but it is worth repeating. When I flew F3A in the 70`s a noise limit was introduced. Since all motors were then two stroke 60`s the solution was to fit a pipe with an additional can welded on. The outlet area could be very small, sometimes just a few 1/16" holes drilled in the end. Power was increased even with this. We found that under contest conditions the wind at 7m produced too much noise to take a reading so this was reduced to 1m measured from the cylinder head at a right angle to the fuselage. I cannot remember the limit figure at this range. For some unknown reason the distance reverted to 7m, presumably because whoever came up with it had not done the extensive testing which we did at the time. The results were repeatable under most conditions with our system.

Club noise meters are very unlikely to be within 3dBa of each other.

I have a long list of motor tests, four stroke, two stroke, petrol and various types of electric, conducted by the Exeter and District Club using a DOE calibrated meter. The results are surprising since motors like the OS 46AX and 32FX squeeze inside the limit. In almost every case the four strokes are well inside. A presumably unsilenced Mills 0.75 reads just 67 dBa!

What is really needed is an after market silencer for 50cc two stroke petrol motors which takes up no more space than a standard one.

I once tried the Brian Winch idea of wrapping the silencer with Rescue Tape but on a glow four stroke and a petrol two stroke it fell off before the models had left the strip.

[Jon H]

Martin you are quite right in what you say about our current noise test method. It is not repeatable in any way due to the external factors involved.

Noise tests also do not have a reading for 'irritation' factor as it is this irritation and perceived noise that gets model flyers in trouble as we hear sounds differently.

The low rumble/burble of a 4 stroke is not as irritating as an EDF even though the EDF might be quieter according to the sound meter. Its the same thing as the beloved dentist drill, just the sound of it is enough to make people cower in the corner, even if they have never been attacked by it!