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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: DB Hurricane paint and finish.
01/07/2020 13:22:33

Cheers Scott. I might pinch a little and just test it on something. I could paint up a test piece and see if it gets munched by the thinners

01/07/2020 11:38:22

Will the thinners eat enamel though? I like enamel's as they are easy to spray and easy to work with. I also dont need to set up a biohazard exclusion zone around the shed to cover off the fumes. The snag is, they melt when you spray over them

Thread: Laser Engines now closed on Friday's
01/07/2020 11:06:17

It should be fine. The hours have just been modified so that we all end up with friday off, which isnt so bad.

Thread: DB Hurricane paint and finish.
01/07/2020 11:05:21
Posted by Ron Gray on 01/07/2020 10:31:15:
Posted by Jon - Laser Engines on 01/07/2020 09:29:14:

How do you thin it Ron? I have to over enamel so its a bit dodgy with cellulose

Cellulose thinner! Spraying over enamel is OK as long as you go really light with the first coat, a real mist coat is needed. Once that's on then you can spray other coats but, again, don't go over thick with the coats, light and many is the mantra!

I have to dust the Mr epoxy on too as that is thinned with celly. Hmmm, not sure what do do as the p67 isnt cheap. Still cheaper than klass cote though

01/07/2020 09:29:14

How do you thin it Ron? I have to over enamel so its a bit dodgy with cellulose

01/07/2020 08:31:33

Yea it will be on the diet fuel from the off. I dont see any need to run with more.

In recent years my go to fuel proofer has been Mr Epoxy from Mick Reeves. Its an absolute nightmare to use, i mean really its just awful, but it does seem fuel proof even if it never actually seems to set solid. Anyway i have a little of it left but its no longer available so i might use that stuff in the area around the engine and then just use some clear matt enamel over the rest. I used clear enamel on my La7 on the areas that do not get that oily and after 10 years its still hanging on.

30/06/2020 20:44:10

Its been a while since i did a Hurricane update as i stopped working it for a while to do other things and also many of the jobs were really boring.

But, we are nearly there now and the model is ready for weathering detail before fuel proofing and balancing. These show a few of the jobs i have been doing in the background.

Engine baffle painted/sealed and dummy exhausts installed

hurri 36.jpg

Wheels made all pretty

hurri 37.jpg

Engine exhaust cut outs made in the cowling

hurri 38.jpg

Undercarriage cover plates painted/installed

hurri 39.jpg

Spinner painted and model assembled to get a feel for how it looks

hurri 40.jpg

Not long now i hope. Just the scary job of c/g and small stuff like the final radio fit and plumbing the fuel tanks. Weather and fuel proofer then should have it finished off.

Thread: Laser Engines now closed on Friday's
30/06/2020 17:14:13

Due to the corona related reduction in work for the engineering side of the business the factory hours have been changed. Until further notice we will no longer be open at all on Friday's. This includes email/phone.

Our opening hours the rest of the week remain the same and Fridays will be back to normal when the rest of the world is.

Thread: OS 91 surpass disassembly
30/06/2020 11:36:17

There is a great deal of metal on one side of OS 4 stroke crankcase so you need to bias your heating towards the cylider/cam chest side to prevent distortion holding on to the bearing. As ED points out, you have to get it pretty hot.

Cam bearings are a bit of a problem. Although it caused a great deal of outrage, i drilled through the crankcase on a really stubborn one i was dealing with and then pressed it through from the other side. A small disk of ali and some JB weld later and you would hardly know it was ever damaged.


Still, its best held as a last resort.

29/06/2020 18:46:44

You can lever it from the bottom using the crank to get the leverage. A hard non metal poker is preferred but a screw driver works too. Just dont slip or you ruin the liner.

Thread: What glues do you use?
29/06/2020 08:31:38

I use cyano for everything apart from u/c mounts, engine mounts, gluing tails on etc. Anything involving ply gets some half hour epoxy, the rest cyano in one form or another.

I know some people go on about brittle cyano joints failing in a crash but i dont accept that argument as you crashed so you get what you get. 


Edited By Jon - Laser Engines on 29/06/2020 08:32:06

Thread: Laser Engines - Technical questions
26/06/2020 10:31:32
Posted by Nigel R on 26/06/2020 10:03:26:

"I already have one new engine on the go with 3 more derived from the same design in the pipeline."

Hold the phone - what new engine is this?

The petrol, what remains to be done before you can sell it?

Sorry if these have already been covered on this thread.

Its very new and most exciting If you are good i will post a photo.

Petrol, need to build more and fly the conrods off them. We have a reliability concern regarding one component but need more info/testing to see if those concerns are justified. That was the whole point of the pre production batch of engines. If all 10 of the pre production engines had been hammered for a year we would have much more data than just me flying my prototype in a gentle floaty biplane. Alas, it didnt work out that way.

25/06/2020 13:59:31

The conversation about how powerplants are segmented across classes of model has been done to death and is a bit beyond the scope of the conversation as related to Laser production.

The reason these smaller engines are no longer produced by us is that the cost of manufacture is such that the finished engine will be too expensive to fit into that section of the market. As has already been pointed out, OS prices are out of this world and i cant imagine they are selling many engines at those prices. Their solution? bring out an engine that is cheaper to manufacture (bushes not ball races, plastic rocker covers, simple carbs etc) and that is what they did with the V series. They are not bad engines, just cheaper. However, £260 is still too much for a 60fs.

In any event, the fate of the 70 is not yet sealed and it, like the 120, has been on the brink for decades. Just as we decide to pull the plug they start selling like hotcakes. There is no plan, just thinking out loud.

So dont get in a flap and dont panic buy one as all you will do is screw up my ability to keep things going. Right now plenty of 70's are in stock and i can build plenty more. But 180's and 360s are gone so they are the focus. Then i need more 100's, perhaps bring the 300 back etc. If i spend the next 2 months building 70's because everyone lost their minds that all falls flat on its face.

A new design 50 is never going to happen. If i have R&D time its going to go elsewhere. I already have one new engine on the go with 3 more derived from the same design in the pipeline. There is also my dreams of a radial, a gearbox for big props and quiet operation, not to mention the petrol engine. All of these things are of greater interest to me and, crucially, more likely to make money which is ultimately the thing we need most.

So, if we could call it quits at this point and get back to technical problems that would be great

Edited By Jon - Laser Engines on 25/06/2020 14:00:04

Thread: Matching an engine to an airframe.
25/06/2020 11:31:58

Astro Hog's will fly on anything from a 50-90 4 stroke. Depends how wild you want it to be! Generally a 70 or 80 fs would be my choice for a Hog

Its the same story with a 52fs. My 72'' Piper Tomahawk is lovely on an Enya 53 4 stroke, equally my old wayfarer biplane of 52 inch was lovely but it was more aerobatic. a friends 55 inch Se5a is also very well powered by a 52 4 stroke. Acrowot's have flown well on 52's, but also go well on a 70.

A great deal depends on how you want to fly. Do you want to fly with the propeller, or the wings? If you are happy to use the wings you can use a smaller engine and do large sweeping manoeuvres that preserve energy and minimise drag. If you want to smash the sticks around and use the prop to get you out of it, you need more power.

I have an 85'' model of around 20lbs that i use as a flying test bench. Its a big ugly old brick and its known as the flying park bench due to its rather beefy construction. I have flown this model on everything from a 120 4 stroke to a 360 4 stroke. Currently its got a 64cc radial engine on it, a few weeks ago an ASP 160 flat twin.

Even on the smallest of the engines my 20lb barge is still aerobatic. No its not as fast as it is with a bigger engine, but it is still able to loop and roll without any trouble.

Power isnt everything.

Thread: Laser Engines - Technical questions
25/06/2020 10:05:01

Ron is quite right. Electric is nibbling away at low end IC and has been for years. 30 and 40 4 strokes never sold that well, 50's more so but even they are starting to come under pressure.

But, there is a fair bit going on behind the scenes here at the moment. There has been a realisation that the accounting side of the business has been a dogs dinner for years and we dont have a clue what anything actually costs. As we all know material cost + machine time + labour cost etc gives you a component price and for reasons i cannot even begin to fathom, no one has ever bothered to work it out.

Anyway the results of these investigations will decide the fate of the 70. If it needs to sell for more than £250 then its likely we will kill it off as it wont sell at that price. In the meanwhile, i still have parts for about another 50 so the end is my no means nigh.

DD, dont get your hopes up. Its a hypothetical thing as it would be a whole new engine from scratch with very few common parts to current engines. I would like to do it, but its not going to happen.

180 in an extra wot? yes, but be careful you dont pull it apart. We normally recommend a 150/5 and even they can pull the tail off in a fast dive. The 180 is well suited to the slightly bigger acrowot XL artf though.

Thread: Great service from
25/06/2020 08:50:47

While it is always a good idea to support domestic retailers where possible the model i wanted was not available in the UK in the Netherlands do stock it (as well as a wide range of other models/accs) and they provided a very swift service to get it over the channel at a very reasonable shipping cost. Email responses were quick, and when the box arrived damaged (thanks DHL) they offered to replace any broken parts before i even inspected the kit. As it turns out there was no damage to the model but their offer ahead of time took the stress out of the whole thing right away.

Has anyone else used them and if so how did you find their service?

Edited By Jon - Laser Engines on 25/06/2020 08:51:05

Thread: Laser Engines - Technical questions
25/06/2020 08:29:53

Sorry DD but the 45, 50 and 62 are dead and even the current 70 is on the brink as they are just not cost effective to make. Also, while they ran well, our 45/50 were too heavy and too big physically. Our current 70 shares most of their dimensions.

I would like to offer a 50 size engine, but it would have to be a whole new design to make it smaller/lighter and that is not very likely im afraid.

24/06/2020 22:26:19
Posted by Martin McIntosh on 24/06/2020 18:39:32:

Other than less mess, is there any other advantage to me if I used 7% oil, price for instance.

Cheaper, cleaner, better economy.

As for availability its all a mess due to the current drama. Eventually we hope to market it as laser 5 pro, laser ultra clean, laser 5 diet? Not sure, we will come up with some marketing buzz word i suspect.

Whatever we do we need to make it clear that its no good for other engines as i cant guarantee that saito/os etc will be ok with low oil. You can see the problem, some clown uses the wrong fuel, engine dies, rants away on a forum that model technics fuel killed his engine. Its not a good look when the facts of the matter are ignored as it throws MT under the bus.

Im sure we can come up with something.

24/06/2020 16:09:36

The sweet smell from the MT fuel is not the oil but their SICAL Additive. All of their SICAL fuels smell like that to some degree or other. Given that the additive does more good than anything else i am more than happy to live with the smell.

And anyway, it could be could smell like petrol face 21

24/06/2020 14:02:52
Posted by Bruce Collinson on 24/06/2020 13:09:13:


To save me going back miles whilst at work, is there a determinant point/date/age for Lasers to use the low oil fuel? Most of mine are under 3 yrs old but 2 100s and my 120 are nearer 10 yrs old.


In theory any engine after 1992 will be ok.

The reason for this is that all engines made after 1992 have the same construction, materials, heat treatment etc.

Engines made before 1992 are not constructed the same and will probably not tolerate the low oil fuel.

There are some caveats though. If your engine has been run on castor for a long period and there is an accumulation on the big end of the rod its possible this will impede the flow of oil to the crank pin and cause a failure. This is true of any fuel, but the lower oil fuel is likely to be more vulnerable.

Equally, if your engine has a crank pin that is a bit dodgy due to corrosion or scoring, this too is likely to be more vulnerable.

Will these more vulnerable engines fail? No idea. There are too many variables to be sure. I suspect they will all be fine, but there will always be that one engine where it all comes together and it breaks.

The risk of a problem is very low, and any engine in good condition should not suffer any ill effects. I test run all of the engines i repair on the low oil fuel and they all go like stink

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