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New Laser engines. What do you want?

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Denis Watkins10/04/2017 19:26:54
2042 forum posts
103 photos

I am surprised, I must only have seen clean petrol models

Perhaps the exhaust pipes, that I have seen, sent the stuff clear of the model

Rich too10/04/2017 19:32:59
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2444 forum posts
933 photos

I was surprised at how filthy petrol motors run and it was one of the reasons I wanted to go with petrol - the lack of exhaust residue. I understand that it can be cut down drastically by using a decent synthetic oil (redline) at 40:1. Recommended by DA and that's what I'll try on all mine in future. The black stuff is after all just unburnt oil?

Edited By Rich2 on 10/04/2017 19:33:46

Jon Harper - Laser Engines10/04/2017 19:36:10
3076 forum posts
129 photos

I think the evo's run 15:1 don't they? I know the saito's run 20:1. At Laser all my testing has been done on 50:1 and 40:1

Rich, you can also run your 155 glow on 10% oil if you like. Mixing a gallon of pro power 10% and a gallon of pure methanol will give you 5 nitro and 9 oil which will be perfectly ok

Steve Hargreaves - Moderator10/04/2017 19:39:31
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6516 forum posts
178 photos

Recommended is 20:1 which at 5% is low compared to glow fuel but still high compared to the 40 or 50:1 that a lot of petrol motors use....I'm currently running 25:1 to try & clean it up a bit. The black goo does reduce a bit with use but it's still there......'orrible....sad

Martin McIntosh10/04/2017 19:43:29
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2116 forum posts
892 photos

I run a RCG 50 and 30 on 30:1 and just get the expected few black spots of oil.

Rich too10/04/2017 20:00:01
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2444 forum posts
933 photos

Wow, I've never heard of petrols running that much oil.

Jon, I am happy to go with what you recommend, no preference for me. As long as I can run all my gloss on the same mix I'll be happy!

Jon Harper - Laser Engines10/04/2017 21:04:47
3076 forum posts
129 photos

yea I cant be sure of other brands will wear 10% oil. Better stick with the laser 5

Timothy Harris 111/04/2017 11:57:31
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511 forum posts
70 photos

I have had no problems with Laser 5 on all my glow engines whether 2s , 4s even the OS55 with tuned pipe is happy revving with it. I also prefer just having 1 fuel type for all. My 4s Lasers are fairly clean, but "Mr Muscle" kitchen cleaner spray and a few wipes easily removes the oil.

Rich too11/04/2017 12:46:27
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2444 forum posts
933 photos

That's great to know Tim, there's nothing worse than having loads of different fuel mixes. I currently have 3 different fuel cans for my petrol motors, but I am going to change them all to redline at 40:1.

Don Fry21/04/2017 17:41:12
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1802 forum posts
25 photos

Bit off topic, but I am assembling a Miles Hawk Speed Six, Phillip Kent plan, with a Laser 180 up front. Now this machine has a distinct spinner, a 82mm flat cone shape, and I am thinking of making it, either turned on a lathe, or in glassfibre. I like the idea of turning it, and making it heavy, because this plane has a reputation for tail heavy, and weight so far forward is appealing. I will be using a commercial backplate, as I have one already. Anyone have any experience of this idea?

Don Fry21/04/2017 17:46:00
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1802 forum posts
25 photos

I have done a ball park guesstimate, and I think the turned unit would weigh IRO 300 grams

Denis Watkins21/04/2017 17:52:42
2042 forum posts
103 photos

Stateing the obvious Donald, is spinning that extra weight on the end of the motor driveshaft could be a problem

Or, balance up the model in the usual way, and turn out a nice lightweight spinner.

Martin McIntosh21/04/2017 20:10:52
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2116 forum posts
892 photos

If it is of any encouragement, my 1:5 Hurricane has a 5" alloy spinner with would you believe it 1kg of lead cast inside! Been like that for many years and the 50cc petrol has a great idle. Tried similar, although much less lead, on a stamped out smaller Traplet Spitfire 1:6 spinner and it flew apart because the metal was so thin.

Manish Chandrayan22/04/2017 01:07:22
310 forum posts
50 photos
What's the considered opinion about gyroscopic effect of the large mass spinning at the tip of nose, does it impede manuverability in pick and yaw axis?
Rich too22/04/2017 07:46:42
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2444 forum posts
933 photos
Posted by Martin McIntosh on 21/04/2017 20:10:52:

If it is of any encouragement, my 1:5 Hurricane has a 5" alloy spinner with would you believe it 1kg of lead cast inside! Been like that for many years and the 50cc petrol has a great idle. Tried similar, although much less lead, on a stamped out smaller Traplet Spitfire 1:6 spinner and it flew apart because the metal was so thin.

It would have a great idle as its got that weight helping it! The downside is that, in the same way that flywheels work, the spin up would be slower...

Don Fry22/04/2017 10:21:50
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1802 forum posts
25 photos

Thank you for the comments.

Martin I am encouraged to have a go.

Mannish, I would guess that the weight will make procession worse when the tail is down at the start of the take off run. But once the tail comes up, and for flight I can't see it making too much difference. It's not a big weight in relation to the mass of the aircraft.

Jon Harper - Laser Engines22/04/2017 12:39:49
3076 forum posts
129 photos

Within reason, as long as the rotating mass is balanced and runs true it will be ok. Note that any out of balance in the prop will be enhanced as it will throw the mass of the spinner out and this will shorten the life of the bearings. But, given that model props come well balanced these days, and even if they don't it not hard to do, and the fact that a bearings change is about £15 and half an hours work its not something to get stressed about

Edited By Jon Harper - Laser Engines on 22/04/2017 12:40:26

Don Fry22/04/2017 13:19:21
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1802 forum posts
25 photos

OK, I will try a turned version first. I have access to a proper toolmaker/engineer, so I think I will be tapping his brains to get me right. List of jobs in my life does not get shorter.

Martin McIntosh22/04/2017 20:22:04
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2116 forum posts
892 photos

I cannot tell any difference in the spin up and it does not seem to adversely affect the model in any way. The motor bearings are still fine. Naturally, I was very careful to use spirit levels when pouring in the lead. Looking back, it would not have made a great deal of difference if the lead was just behind the nose ring, which I eventually did on the Spit.

Jon Harper - Laser Engines27/04/2017 12:13:19
3076 forum posts
129 photos

I am bringing discussions from other threads over here so we do not get distracted from the OP

For those who didnt read them the 'issue' was my mention of a prototype laser 100 running on petrol. This resulted in some considerable interest and suggestions that i need to hurry up and make some.

So, Laser 100 petrol for £375. Show of hands please. I will wave it under my bosses nose and see if it motivates him to move quicker than geological time.

Please note i have not even test flown my lash up prototype yet so it could all go horribly wrong but it ran nicely on the bench.

I know this goes against what i said many moons ago about not doing engines smaller than 30cc, but i think i may have resolved the technical issues preventing it from working to my satisfaction.

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