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Member postings for Jon - Laser Engines

Here is a list of all the postings Jon - Laser Engines has made in our forums. Click on a thread name to jump to the thread.

Thread: New old stock - SC30FS - just purchased.
21/01/2020 17:53:38
Posted by SIMON CRAGG on 21/01/2020 17:50:41:

I would run it in, in the air.

Just get the settings ok on the ground good for stable running, and slightly rich........and fly it.

All that lovely cool air, free running prop = great engine!.

I gave up wasting precious hours running in on the ground years ago, and never had a problem!

exactly. All of my engines get no more than about 5 minutes of ground run time. Just long enough to set up the needles and make sure i got all the pipes in the right place. If nothing leaks then its cowl on and up in the air.

21/01/2020 16:57:32
Posted by Peter Christy on 21/01/2020 16:54:30:

Never had a problem running an OS20FS inverted in an Attila. Just be careful not to flood it and cause a hydraulic lock when starting.


Very good point. I have seen many a broken crank pin on small engines because of this. Hand start, or at least hand check for fuel locking.

Thread: 6 Turning 4 Burning
21/01/2020 16:56:03

Its a monster. Look at that cute little B17 parked in front of it!

Thread: New old stock - SC30FS - just purchased.
21/01/2020 16:52:19

No problem with it inverted, just make sure the tank is not too high and the slow run needle as lean as possible. When the engine is running the oil in the crankcase is smashed into mist and wont be collecting anywhere. The usual cut at idle with inverted engines is due to fuel collecting in the inlet manifold. Once the engine speed increases and there is enough flow through the valve it picks up all this fuel in one blob and it cuts out. Leaning the slow run as much as possible prevents this excess fuel accumulating.

Poor compression, you probably have been running it to gently. Use a small prop and rev the (prop)nuts off it.. In general with ASP engine run in i pre oil them, then fire them up and run for about 2 minutes quite rich at around half throttle. i then wind them up to full chat and very quickly (about 3 seconds) tune them for about 90% of peak rpm. I then come back down, make sure the slow run needle is half decent and then just play with it. Up and down on the revs, little bit of idle, a few 5-10 second bursts at full power with some half throttle cool down in between. After 5 minutes of that i stop it, let it cool, start it, tune for 95% of the max it will give and then go fly. 3 or 4 flights later i change to the normal flying prop i want to use and retune. That's about it and you can do it all in about 2 hours if you only take one sandwich break


Edited By Jon - Laser Engines on 21/01/2020 16:53:37

Thread: Kings Lynn Model Shop
21/01/2020 13:46:15

I know this is an old thread but to update it with my most recent experience..

Yesterday at around 3 i ordered some paint from kings lynn models. An hour later i got a call to say one of the items i wanted (RAF roundel red) was unavailable but an alternative (US insignia Red) was. I took the alternative and my paint just arrived. Under 24hr from click to delivery and with a problem to solve along the way? Cant fault it.

Top marks all round.

Edited By Jon - Laser Engines on 21/01/2020 13:46:45

Thread: 20 years out of date !
21/01/2020 12:59:48

Im not brilliant at flying heli's. I can loop and roll but its not really my thing and i find my t-rex 500 a very nervous machine to fly as it, like your machine, is intended for a great deal more than i do with it.

You might want to talk to a shop like midland or someone who knows heli's well and can recommend setup changes to make it more friendly. I suspect you can drop the head speed a little, use softer dampers and do other magical helicopter related things to calm the whole thing down.

21/01/2020 11:42:15

Is that a logo 550? If so midland list a Savox 1257/1290 Servo Set for their combo deal but they arent cheap! I suspect they would also be overkill if you just want to fly about a bit and not wring its neck.

Thread: Brian Taylor Harvard AT6
21/01/2020 11:31:55
Posted by David Davis on 21/01/2020 09:53:01:

Thank you gentlemen, this will be my first experience of flying a model with retracts so I'll keep practising those landings "sur la piste."

if using retracts fit oleos as they absorb the shocks better than wire.

Wire will protect you more in the event of a faceplant, but they will also turn good landings into bad ones!

21/01/2020 09:49:17

If fitting a laser just keep an eye on where the fuel tank will have to go. I suspect you will need to mount the engine on its side or perhaps upright if it will fit the cowl.

Thread: DB Hurricane paint and finish.
20/01/2020 19:18:37

In fairness, part of the delay is that i keep putting it together and just looking at it.

Apparently they dont build themselves no matter how long you look at them


20/01/2020 14:59:05
Posted by Don Fry on 19/01/2020 17:36:49:

That point in a build where there is a months worth of bits to do. Nothing much to show. I am amused when someone is selling a bare airframe, not fitted together, no bits done, and the say 80% complete. That is still a nice colour scheme.

yep. Whenever a model gets the point where i think i have a handful of 10 minute jobs to finish i know its about 2 months away!

Chris, i will keep going and i have a MkII version of my colourised photo as i think the grey was too blue last time.


Thread: Stuck piston ring
20/01/2020 14:10:28
Posted by Wilco Wingco on 20/01/2020 13:48:05:

When I had the head off to replace the valve spring the bore looked fine, don't know if I would see any signs of rust? Not sure how long the engine has not been run, bought at a swap meet, so I will risk the "Italian Tune up" and see what happens. Thanks chaps, watch this space. yes

If the ring is rusty you will likely see rust coloured oil in the bore as you move the piston up and down. If there is any suspicion of rust on the ring or bearings then its worth stripping it down.

Slightly noisy bearings should be replaced immediately as eventually the cage will fail and metal fragments will fall into the crankcase. This makes a right mess so if you are in any doubt take it to bits and have a good look.

20/01/2020 12:18:27

If its not rusty then it sounds like it needs an italian tune up.

Go a good inch smaller than your normal prop, fire it up, full chat as lean as it will go then throttle back by about 500-1000 rpm. Leave it there for a little while, back up to full power, idle, rev up, generally slap it around with a decent number of accelerations from idle to full power and plenty of revs.

After a few minutes of that it should be right as rain. If not, slap a new ring in it and do it again

Thread: Synthetic instead of caster oil?
20/01/2020 10:19:17
Posted by Nigel R on 20/01/2020 09:38:41:

" 100/1 oil/ petrol....try that with your laser ( substituting methonal obviously)"

how much lubrication does the petrol itself count for?

methanol isn't lubricating at all, is it?

so would presume any glow fuel will always need more oil than an equivalent petrol engine?

In a 2 stroke there is an argument for the lubricity of petrol helping out a bit but not in a 4 stroke you burn it all off and only have oil in the crankcase.

All that said, petrol is a pants lubricant anyway.

20/01/2020 08:41:30
Posted by Frank Skilbeck on 19/01/2020 20:52:07:

And of course if you say halved the oil content from 20% to 10% then you'd actually be reducing the oil flow to the engine by around 55%, not 50%, as you'd have to reduce the mixture flow to keep the fuel flow the same. And you should get around 12% more runtime on the same tank.

Been running my Laser 150 on 10% oil, has almost a gallon through it, no ill effects so far and removing the rocker cover shows these very well lubricated.

quite right. The leaner mix will reduce overall consumption and the fuel will be cheaper as its the oil and nitro that are the expensive parts.

If mixing yourself you can drop oil to 7% if you want. Which oil are you using anyway?

Edited By Jon - Laser Engines on 20/01/2020 08:41:46

19/01/2020 20:30:03
Posted by paul d on 19/01/2020 19:47:49:

I will however beg to differ with Jon with his comment about the presence of oil adding nothing to combustion ( it does....)

No im with you. Oil makes a difference, just not in the context of the conversation here.

15% of castor, ML70, wont make any meaningful difference which oil you use. RPM might change slightly due to viscosity and lubricity factors, but unless there are combustion enhancing additives, like the model technics SICAL, it wont matter at all.

As you rightly say model engines are extremely crude in real terms which is again why i say it will make no difference as i am trying to keep the conversation within the scope of model engines and their operation as opposed to the ultimate tuning guide for internal combustion.

As a side note, i accept your challenge i have some methanol and i have some oil. All it will cost me is a conrod so i will fire up a laser on 100:1. I know they work on 50:1 on petrol, and i use petrol at half the rate of glow fuel so... i have reasonable confidence it will be ok. I already flew two of our engines on 5% oil for a year with no ill effects and we are looking to introduce 7% oil fuel as our standard. It will be an interesting test

Thread: DB Sopwith Pup flying weight
19/01/2020 20:15:02
Posted by George P. on 19/01/2020 18:25:16:
Posted by Jon - Laser Engines on 19/01/2020 16:54:00:

Also, if its getting porky dont use the ball bearing rigging gripper things. Loads of people have told me they fail so its not worth the risk.

Now that is a bit of a worry but glad you mention it ! I have used the grippers and was hoping they would be reliable. Anyone out there who can vouch for the system? Or should I be thinking of some kind of contingency plan before the maiden in Spring?

I cant speak from personal experience on this but a number of my customers have commented on it. Often when ordering spares for their now damaged engine.

One chap was using those grippers on a 1/4 nieuport and i mentioned it to him when he ordered the engine. He was already committed to using them but was able to get inside and installed a collet so that if they did fail there was only a small amount of slack in the system and this would hopefully keep the wings on. He called me some time later to say that he experienced failures in the rigging on about 25% of his flights and the wheel collets he installed prevented disaster. many others have said similar things

Now i cannot vouch for the quality of the installations and i dont want to malign DB when i have not tested it myself, but given the risk factor i would say its better safe than matchsticks.

Thread: DB Hurricane paint and finish.
19/01/2020 17:02:14

Not sure how much interest there is since we stopped arguing about swastika's but the Hurricane is still moving along.

Most of the work has been fiddly and there is not much to show but a few milestones have been reached with the ailerons and flaps installed temporarily. The ailerons have been held up as i apparently lost their hinges but i had enough to install them and set up the servos.

The flaps have been installed using screws as i intend to make them removable in case the get damaged in a belly landing for example. I need to get their servos and linkages installed then then are more or less done.

I have also added some minor scale detail to the top wing surface. I am not going mad so there are just a few bits to break up the smooth surface.

I have also had another go at colouring in a black and white photo. Using colours lifted from a moderns photo of a hurricane i did some stuff in photoshop and came up with the following. Its not 100% by any means, but it gives me something to aim for


Thread: DB Sopwith Pup flying weight
19/01/2020 16:54:00

You say you calculated the c/g, are you sure its in the right place?

Also, if its getting porky dont use the ball bearing rigging gripper things. Loads of people have told me they fail so its not worth the risk.

19/01/2020 14:50:01

i agree with pat. My 1/4 stampe is 16lbs and while its got a longer nose its not got any lead in it at all. DB also seem to suggest 15lbs as a flying weight.

How much of your weight is lead?

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