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Laser Engines - Technical questions

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David Davis02/10/2019 07:08:12
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3431 forum posts
611 photos

Thank you gentlemen. It appears that I have a 62 and a 70.

Alan Hilton03/10/2019 08:15:20
100 forum posts

Hi Jon

I can’t access the Laser website ,is the site OK ?

Alan

Manish Chandrayan03/10/2019 08:54:04
595 forum posts
70 photos

I too can not access the Laser web site since past few days

Jon - Laser Engines03/10/2019 10:30:37
4832 forum posts
180 photos
Posted by Alan Hilton on 03/10/2019 08:15:20:

Hi Jon

I can’t access the Laser website ,is the site OK ?

Alan

nope, looks like its busted. I will try and fix it when i get back from my holiday.

David, apologies for the radio silence. I would agree that you have a 62 and 70

David Davis03/10/2019 16:18:05
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3431 forum posts
611 photos

No need for apologies Jon, I didn't expect you to reply when your were on holiday. It was very good of you.

Alan Hilton03/10/2019 17:57:06
100 forum posts

Hi Jon

Hope you are having a good holiday ,sorry to disrupt it

Alan

tigerman20/10/2019 12:32:18
187 forum posts

I have a Laser 80 spare now, just lost the top wing on my old Wots wot in flight and it is really old now and needs replacing ,not worth trying to repair it . Seagull Models have just brought out a 90 inch L-4 Grasshopper .It's flying weight is meant to be 6 Kilos and it is for a 15cc to 20cc petrol engine (horrible things these petrol engines ) Going by my calculation if it is for a 15cc/20cc petrol engine a Laser 80 should be OK but I I find sometimes the manafactures recommendation are not that great .I find it is best to check .Anyone help me out on this combination a Laser 80 in a Seagull 6 Kilo L-4 Grasshopper .I do not want to fork out £350 only to find the Laser 80 is not the right engine for this model Failing that I do not really want to buy another Wots Wot but that will be my second choice .

Brian Stevenson 120/10/2019 13:49:29
45 forum posts
Posted by tigerman on 20/10/2019 12:32:18:

I have a Laser 80 spare now, just lost the top wing on my old Wots wot in flight and it is really old now and needs replacing ,not worth trying to repair it . Seagull Models have just brought out a 90 inch L-4 Grasshopper .It's flying weight is meant to be 6 Kilos and it is for a 15cc to 20cc petrol engine (horrible things these petrol engines ) Going by my calculation if it is for a 15cc/20cc petrol engine a Laser 80 should be OK but I I find sometimes the manafactures recommendation are not that great .I find it is best to check .Anyone help me out on this combination a Laser 80 in a Seagull 6 Kilo L-4 Grasshopper .I do not want to fork out £350 only to find the Laser 80 is not the right engine for this model Failing that I do not really want to buy another Wots Wot but that will be my second choice .

80 four stroke in a 6 Kilo light aircraft?

From my OS 56 powered 84 inch 4.5 Kilo Airsail Auster AOP9 experience you will REALLY have to fly it in a 'full-size' manner, particularly on take off, even from a concrete surface. GENTLY is the word. I have been flying full size aircraft of similar type since the 1970's and I still find the Airsail tricky.

It's quite rewarding as you always have to fly it in a scale manner, 100% of the time. These are draggy aircraft and can slow down very quickly, and applying the limited  power of such engines in such a size/weight of model  takes some time to have an effect - you don't always have space to put the nose down. But it can get a bit dull after a while. Greater power NEVER does any harm and will get you out of 'situations' if you mess up. So why bother?

PS: My choice for the Grasshopper would be the 160 (not the 120) OS Gemini twin. But then you are talking £1100 plus total. Will you get five  times the pleasure of an OS25 two stroke powered  Junior 60?

Edited By Brian Stevenson 1 on 20/10/2019 13:56:12

Edited By Brian Stevenson 1 on 20/10/2019 13:57:46

Edited By Brian Stevenson 1 on 20/10/2019 14:14:58

Piers Bowlan20/10/2019 14:15:04
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1883 forum posts
45 photos

Tigerman, perhaps you are an ARTF man at heart but would you fancy building a Piper Cub from a plan? It is the winter building season after all and apart from the satisfaction of scratch building, you may save yourself some cash too? I googled 'Piper Cub plans' and came up with dozens of designs on Outerzone, Aero Fred and Sarik Hobbies, as you might expect. One from Sarik is an old Boddo design at 84in span, for '80 sized engines'. Whether such a model is over/under powered depends to some degree on the design and how you plan to fly it. There are Cub designs in the 70in span category which might perform in a very spirited fashion on a Laser 80. It might depend on your expectations.

Edited By Piers Bowlan on 20/10/2019 14:17:21

tigerman20/10/2019 14:40:06
187 forum posts

Hi Piers ,thanks for your reply but you really do not want to see a model I have built ,I get more glue on the workshop then I do on the model ,my wife has banned me from bring any model into the Kitchen .I have a mate who will only build from plans and he keep getting me to build a real model ,I really wish I had the skills to build models .Has I said my mate builds from plan ,at the moment he is building a Hurricane and I can only drool over he's skill at building .I afraid it is ARTF for me Sorry but thanks for your reply .Looks like I will have to revert to plan B ,One Wots Wot coming up

Piers Bowlan20/10/2019 15:40:03
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1883 forum posts
45 photos

'Glue on the worktop' Yes, wives can get pretty cross about that sort of thing teeth - can't think why! Don't worry, I'm in the same boat.

I think the thing is, to build something not too big or too complicated so that it gets finished, even if it is not the sort or model one usually flies. Likewise, artists don't become artists overnight, it takes loads of practice, - same with model aircraft building. Some builders may never be any good but they get satisfaction from the process, and the finished article is 'theirs', even if what they have created looks like a frankenstein monster and flies like a drunkard!

Good luck with plan B tigerman, it will be fun anyway, which is what it is all about.

Edited By Piers Bowlan on 20/10/2019 15:57:39

Martin McIntosh20/10/2019 17:01:39
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2948 forum posts
1083 photos

If you are still toying with the idea of a Laser 80 in a 6kg model then I would say forget it. I have one and it is a great motor, currently in a TN Mustang for which it is a little too powerful but I tried it in a Dalotel which previously had a YS 63 but although giving an improvement in performance was replaced with an OS 91FX.

What I would like to know is what is the span of your proposed Wots Wot and the expected weight.

Denis Watkins20/10/2019 18:18:17
3912 forum posts
61 photos

Agree with Martin Mc

The Laser 80 is comfortable in the 10lb range nearer 4kg models

Edited By Denis Watkins on 20/10/2019 18:18:34

tigerman20/10/2019 19:04:28
187 forum posts

Yes I think a 6 kilo model for a Laser 80 is asking to much for the poor Laser .Has I said I had the Laser in a Wots Wot and I like flying the Wots Wot with the Laser 80 .It had more then enough power ,flew slow ,flew fast ,very acrobatic and a real pleasure to fly but I thought Ripmax had stop stocking them .I now see that a lot of the popular Model shop have them back in stock . So I might stick with the Wots Wot .

Jon - Laser Engines20/10/2019 20:17:17
4832 forum posts
180 photos

This will boil down to performance expectation.

The 80 would fly a cub of that span/weight without any trouble but dont expect more than scale performance. To be honest, i dont quite know why the model is so heavy as 6kg seems quite porky for a 90 inch cub. I have flown the black horse big cub (92 or 96 inch, cant remember) on a 100 and it was well over powered for scale. A friend also had a 90 ish inch cub with a laser 150 in it and it was very much over powered. An 80 would do the job without question, especially if you can get the weight down a bit and dont mind being limited to scale performance.

That said, i expect the performance to be better than scale as we recommend the 80 for the DB Auster and that model is 87 inch and 4 kg. I cant see why the seagull model is 6kg. Perhaps that includes the weight of a bigger engine?

Frank Skilbeck25/10/2019 13:40:15
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4488 forum posts
101 photos

Last year I acquired a 2nd hand Laser 150, the version with the vertical plug and Irvine carb, it runs great but spews oil out of the front bearing. I remember the seller telling me the bearings had been replaced but I think the front bearing must be faulty. Before I strip the engine down is there anything else that could cause this to happen?

Lastly any recommendations on replacement bearings.

Thanks.

Martin McIntosh25/10/2019 14:34:00
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2948 forum posts
1083 photos

Blocked crankcase breather maybe?

Jon - Laser Engines25/10/2019 15:43:33
4832 forum posts
180 photos

The usual suspects are blocked breather, wrong bearing, failed bearing, dead rings, scored cylinder, bent crankshaft.

Usually very oily engines are suffering in the ring/cylinder department and the crankcase pressure increases significantly due to a mix of additional blow by and the hydraulic action of the sheer amount of oil blocking the breather. This added pressure means the air in the crankcase being compressed by the falling piston will escape wherever it can.

if you want to change the bearings the front is a 6001-2rs with the rear seal removed. i would clock the crank to see if its straight (a bent one makes bearings act like a wobble pump) and see if the rings/bore are any good

bert baker25/10/2019 16:18:50
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1449 forum posts
304 photos

I would send it to Jon to service.

He did my 180 a short while ago,

Very pleased with service and price

Bert

Phil B26/10/2019 14:29:13
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155 forum posts
150 photos

I am working on an elderly and rather neglected Laser 75. I know these are no longer supported but it was cheap and I think worth some work I got the thing mostly apart with a view to changing the bearings and cleaning it up. The front bearing is a little rough but after flushing out some of the old gum it spins quite freely. As the prop driver is refusing to part company I either have to buy a puller or I am wondering whether just to reassemble and see how it runs. Similarly the cam shaft bearing spins nicely now, but there is a little play. How important is this? Should I change it and if so how do you extract the cam shaft with its pinion?

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