Laser Engines - Technical questions

[Jon H]

Its more that without all that oil clogging up the place you get more air and more fuel. The mixture is also less viscous so i imagine you get better spray from the spraybar. Less sticky oil also gives less drag within the engine, less hydraulic action in the crankcase preventing it breathing.

At idle there is less oil to pool in the plug i would imagine. Its a win win really.

The only note of caution would be to say not to run the engine really rich. If you run the engine slobbering rich the excess of fuel in the crankcase will wash all the oil out, and thats bad.

[Jon H]

Posted by Tim Flyer on 14/05/2020 15:53:04:

Wow 5.6hp is superb for 60 cc 4s !

Perhaps i should video it next time

[Tim Flyer]

Sorry to hear about your club that’s a shame. We have had lots of debate about opening and a number of adjustments, but yesterday we opened , and so far it’s been great with everyone being sensible. There were just 3 of us today.

yes a video would be nice ...I think your twins put other makes to shame on their power, it must be the twin carbs helping too 

Edited By Tim Flyer on 14/05/2020 16:08:52

[Anthony Scott 2]

Tim, from where did you obtain the low oil content Laser 5, please? I recently bought some MT Laser 5% for my 180 & could only get 15% oil content.

[Tim Flyer]

I bought it when I visited the laser factory just before lockdown here , I’m sure Jon can help ..

[Jon H]

Posted by Anthony Scott 2 on 14/05/2020 16:13:38:

Tim, from where did you obtain the low oil content Laser 5, please? I recently bought some MT Laser 5% for my 180 & could only get 15% oil content.

He picked it up from me here at the factory. Currently the fuel is a 'prototype' and MT are not producing it commercially.

We need to work out a way of distributing it as its sales will be low if its only useful in a laser so the shops are less likely to carry it, also we need a way of making it really obvious that it is only for use in lasers as engine failures may result if used in other brands of engine and this would reflect badly on MT even though its not their fault.

In truth i think OS, ASP and Enya engines would probably be ok on 7% oil. Not sure about saito though. Either way i wont be recommending this low oil fuel for other brands as i cannot guarantee it will work.

Edited By Jon - Laser Engines on 14/05/2020 16:23:02

[Anthony Scott 2]

OK, thanks.

[Nigel R]

I guess the existing 10% Laser mix, plus a gallon of neat methanol, would be the easy route for now?

"My club has reopened as electric only as someone had plonked a bunch of horses next door and everyone is paranoid about them getting upset."

They'll be fantastically disinterested in my experience.

I used to fly a piped 46 Meteor which was neither slow (nor particularly quiet) and the local semi-wild horses (New Forest) had to be shoo'd off the runway in order to land, quite regularly.

[Dirk Witvrouwen 1]

Posted by Jon - Laser Engines on 14/05/2020 16:22:35:

...

We need to work out a way of distributing it.......

And in doing so, not forgetting your mainland EU customers

For what it's worth relating 'your' horses, those next to our field coudn't care less.

[Denis Watkins]

Posted by Nigel R on 14/05/2020 16:42:27:

I guess the existing 10% Laser mix, plus a gallon of neat methanol, would be the easy route for now?

"My club has reopened as electric only as someone had plonked a bunch of horses next door and everyone is paranoid about them getting upset."

They'll be fantastically disinterested in my experience.

I used to fly a piped 46 Meteor which was neither slow (nor particularly quiet) and the local semi-wild horses (New Forest) had to be shoo'd off the runway in order to land, quite regularly.

Same here Nigel, with livestock sharing at our field these last twenty years

And they have absolutely no interest in I/C flying whatsoever,

[Jon H]

Yea i know, horses dont give a rats. The rich people that own them on the other hand demand a 10 mile exclusion zone.

MT Laser 5 fuel is currently 15% oil so you can thin it some for sure. I wouldnt use more than 3/4 gallon though as the ratios get all complicated.

While on the subject of power, i just test ran a 200v. 9400rpm on apc 17x6. Thats 3hp

[Martin McIntosh]

Jon, are we talking about ADMFC re the horses because this is the first I have heard of it. Got their mail yesterday which said that we can go up next week but nothing else as yet.

Oil. All of my Lasers run very clean anyway but may give the 7% a try.

[Jon H]

Posted by Martin McIntosh on 14/05/2020 17:36:43:

Jon, are we talking about ADMFC re the horses because this is the first I have heard of it. Got their mail yesterday which said that we can go up next week but nothing else as yet.

 

Oil. All of my Lasers run very clean anyway but may give the 7% a try.

yep. I asked Peter about flying this weekend and was told its going to be electric only. I asked Mick and he told me its going to be at least 2 more weeks

Its not completely the end of the world, i mean i can fly my electric heli, but as its not flown in 3 years you can tell how much i enjoy flying it vs my planes!

Edited By Jon - Laser Engines on 14/05/2020 17:47:54

[Martin McIntosh]

I do wish that they would make this clear to the membership. New horses have never been bothered by our models in the past.

Many of my new builds are electric EDF which will all need a hand launch which I don`t want to do on a maiden by myself (+ one i/c, hand launch only). I really just want to go and run motors on the ground at the moment so that should not bother the nags too much. Can probably find a leccy or two to have a go with, Lancaster maybe?

[Chris Walby]

New Laser fuel report from todays flying, no problems with social distancing as most of the time it was just me and then the single person turned up for a bit.

 

First up was the trusty 70 in the Acrowot, lovely combination of minimal weight and enough power. Minor problem with the tank bung, but after that started no trouble and warmed up. Once up to temperature WOT needed a tweak (1/4 turn in) and it was maxing out no problem. bottom end and tick over seemed a bit rough, but pick up was no issue. Had a nice flight and seems to pull and pick up very well. It was still a bit rough at the bottom end even at the end of the flight so next time out I'll have the cowl off and set everything back up. Minimal cleaning required

 

Next up was the 180 Yak, fuelled and started no problem and was running just okay as was. Now this beast presents a problem to me as the engine is inverted, exhaust points slightly towards the main needle. I have to tie the tail to the bench, kneel under/to one side and adjust form there, I'll adjust things when I change the cowl for easier adjustments. Once warm it was adjusted with a small turn in the main needle. Taxied out and flew the usual routine of big aerobatics. I normally fly it half to 3/4 throttle, but today it seemed happy to do that or WOT for the nice big verticals and loops. Hardly any cleaning required

Last but not least as I ended up having 4 flights with the pair of 70's in the dual Ace. Start, warm up and adjustment of main needle only to both. Taxi out and a very clean pick up to 3/4 throttle for take of with a nice climb out. Took a couple of circuits to get my thumbs trimmed back in. Slow low passes, fast drop in passes, rolls and loops with not a hint of a problem, Bit of cleaning because the exhaust rubber deflectors had rotated to face the fuselage!

Summary

• No problems just swap over fuel
• Minor adjustment on the main if its set up correctly, if not it might benefit from a standard tune up
• Tick over, pick up and WOT all seem very good and it might even rev out a bit higher or it could be because it seems a bit cleaner between 3/4 and WOT

Right that's me converted and I am actually looking forward to getting the Mossie out (pair of 70's) and seeing how that goes, I think with a bit more pull out of the Lasers it will really suit the more draggy airframe.

As ever, big thanks to Jon for all of his hard work in building, testing and putting up with my questions.

 

 

 

Edited By Chris Walby on 15/05/2020 20:39:35

[Tim Flyer]

My Laser 200v ran great on the new fuel today ... just a bit of main needle tweaking .. I even did a post flight throttle test 😊

**LINK**

Edited By Tim Flyer on 15/05/2020 22:56:50

[SR 71]

Where in England are Laser based,

[Jon H]

**LINK**

[Silver Wolf]

Just an initial look at some cooling baffles, I was hoping not to have to cut the cowl.

A rough estimate gives equal area for inlet and outlet if no cut out in cowl. Not sure if the baffles will enable me to get away with not having to cut the cowl.

With the area marked on the underside of cowl, gives a 2:1 ratio, if no cut out on underside then it is 1:1 for outlet to inlet.

The area marked on lower side of cowl is for a dummy exhaust, this may reduce the efficiency of the baffles.

Options 1: Cooling baffles and no cut outs.

Options 1: Cooling baffles and exhaust cut out

Options 1: Cooling baffles, exhaust cut + an area on underside of cowl.

Any comments and suggestions chaps.

Kind Regards

SW

[cymaz]

If it were me I would have a opening in the bottom..see if you can get the baffles tighter to the fins.

Jon might have an idea or two

[Martin Harris - Moderator]

Chipmunk?

My 1/6 scale version is powered by an OS 52FS and uses the scale outlet area at the back of the cowling with a tight exhaust outlet, tiny scale fuel priming access port and small needle valve hole being the only possible exit holes in the cowling. It needs no baffling and has never overheated in the 17 years since I built it.

Edited By Martin Harris on 17/05/2020 17:54:40

[bert baker]

Would it help it the propeller went clockwise

[Martin Harris - Moderator]

Depends which way you look at it but flying backwards would do nothing for the cooling airflow! I suppose it would help scale fidelity though.

...or have I missed the point?

[bert baker]

On the full size the prop goes the other way round and the cooling air goes in onto the cowl on the port side

Often wondered with chippy and Moth models if it would be better air flow into the cowl from prop wash if the opening was on the wrong side

[Jon H]

The cooling should be fine SW. That cowl lip will draw the air through nicely so i dont expect any problems.

Prop rotation? at our scale its a non issue. Full size sure, but we fly very much faster in real terms than full size and we are dissipating nowhere near as much heat.