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New Laser engines. What do you want?

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Jon Harper - Laser Engines07/12/2017 12:41:50
3162 forum posts
129 photos

remember to take a photo of the cams before you take them out. There are no timing marks to help with reassembly and if you call asking for help because you forgot to take a photo i reserve the right to laugh at you

trebor07/12/2017 13:19:52
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1293 forum posts
155 photos

laugh thanks for the tip. I just took the other engines head off so now I will leave them to soak up white spirit for a while. Then compare the stroke and bores, I have some paperwork that came with it showing details of different motors.

bert baker08/12/2017 00:51:13
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894 forum posts
192 photos

Just had a look at my 150 Id . It has my initials one end of mount and J11 at other end

Martin Harris08/12/2017 02:27:52
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7189 forum posts
178 photos
Posted by Martin Harris on 06/12/2017 13:02:06:

Jon - I'm having a little difficulty following the labelling logic - does the date code come before or after the buyer's initials - or was it at the whim of the builder?

My rather vintage 62 (BA/imperial hex sockets) has the letters KRB followed by 62 so logically it must be a prefix i.e. K=1992/3 as I believe the 62 wasn't offered until 1989 whereas you've identified Trebor's dirty engine (TFL) by the suffix L

laser 62.jpg

P.S. It wasn't me that drilled the extra mounting holes but they have come in useful!

Interesting afternoon today...

This poor old Laser came to me from a deceased member a few years ago and although looking quite good on the outside, was a sorry sight when I looked inside it. There was a thick gunge of rust/castor mixture and a quick enquiry to Neil Tidey regarding spares such as cams and followers revealed that there was little if any availability but he encouraged me to drop in some new bearings, clean up the internals and give it a go. I did so, bench ran it and oiled it up for storage until I found a suitable home for it.

My Glen's CAP 232 had a slight mishap the other day, necessitating refixing the firewall and I realised that the Laser would fit with very small mods, leaving the option to return the Irvine 53 easily should the need arise. Unfortunately the inverted position to suit the existing throttle linkage left the carb rather low but I thought it would be interesting to see how the Laser would cope.

Starting was excellent and the first flight was straight after the factory approved full throttle level test (good long duration during a noise test) so I eschewed my usual (sorry Jon!) nose up check and took to the air, where performance on a 13 x 6 was OK but not sparkling - slightly inferior to the Irvine on a 12 x 6. However, an attempted prop hang was greeted by silence and a tail slide so I landed, restarted, richened a tad and tried again (after a nose up - sorry Jon!)

The prop hang test was fine although it fell out of it and the engine sounded a little restrained so I gained height and gave it a powered descent to clear its throat...which it did briefly and then went rich. This happened again a couple of times.

...so I landed, leaned it a fraction and tried again. Result, still going rich with high airspeed...OK, try the prop hang...dead stick! Too rich and too lean on the same flight?!?

Conclusion - the excessively high tank coupled with the small boost from the forward facing vent (open to direct airflow as I had left the cowling off) was causing a large change in mixture. I suppose the way forward is to mount it sidewinder or convert to tank pressure (sorry Jon!) for more consistency and maybe revert to a smaller prop and get a few more revs as it was only producing 80 dB which gives me a little leeway.

And it did sound so much better than with the two stroke!

Jon Harper - Laser Engines08/12/2017 08:47:19
3162 forum posts
129 photos

ahh the nose up test, what utter pointlessness i really dont know why you guys ignore me, it really is a waste of time. Perhaps i need to employ a celebrity to advocate the no nose up test method. Everyone seems to take what they say as gospel!

anyway you have nailed it, the tank position is wrong meaning you have the engine unrealistically lean (in terms of needle position) when level making it go very lean in the vertical.

Tank pressure might help you, but the only real answer is to move the tank or move the engine

Oh and try a 12x6 on it. If its a 62 it should be pretty zippy like that.

Timothy Harris 108/12/2017 10:02:07
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535 forum posts
81 photos

Sorry to change the subject a bit but here is a quick one that should make Laser owners happy with their choice of an easy handling engine. I am very happy for John to keep his engines the way they are and not pump them , put big carbs on etc . One of my club mates bought a YS 160dz second hand . It was almost new when he got it. It took ages for him to set it up and get it reliably running . It has its own what seem very esoteric operating rules . Anyway after lots of wasted hours and buying high nitro fuel he finally got it going . Yes it’s a very powerful “ nitro moda” . He recently broke the nice carbon fibre prop it came with . He replaced it with a wooden one now the prop slips despite tight bolts and I think he might need to make a sandpaper washer. Anyway some of it might be to him starting it “ too wet” and getting kick back. I will have to observe. However it’s clear to me that there is a big price for “high performance” which can be a lot of hassle!

Martin McIntosh08/12/2017 10:19:28
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2136 forum posts
895 photos

There are diesels, glows, petrol and YS. I have a few of the latter and a kick back is a sure sign of a weak start on these, not rich. Can easily cause a broken shaft. Won`t go into the starting procedure here as it is the wrong thread.

Timothy Harris 108/12/2017 10:35:51
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535 forum posts
81 photos

No worries Martin I don’t need them thanks . What my point was that there is a huge benefit in the current simple Laser design which gives incredibly easy handling. I will not be buying a YS so don’t need to worry about their peculiarities( the guy already has the handbook.).  When I just want power I am happy to use 2 strokes which I am more than familiar with and are very easy to operate.

Edited By Timothy Harris 1 on 08/12/2017 10:39:36

John Stainforth08/12/2017 10:47:48
98 forum posts
30 photos

Jon, I do the nose up test simply to check that the clunk line in the tank has not fallen off!

Jon Harper - Laser Engines08/12/2017 12:15:10
3162 forum posts
129 photos
Posted by John Stainforth on 08/12/2017 10:47:48:

Jon, I do the nose up test simply to check that the clunk line in the tank has not fallen off!

Finally, a legitimate reason

 

As for the YS debate i see it like this. They are powerful, well made engines but are not really suited to day to day club flying. They are too fussy for many modellers who just want the easy life of an engine that works. Installation is also more complicated due to the pressurised fuel system. 

A friend of mine had 3 YS's and now has none. They worked well once he figured out how to get the best from them and in that state they were very reliable. But, he got tired of the faff factor and their diet of expensive/high nitro fuel was not sustainable. He now runs Enya 4 strokes for the most part with a laser 150 powered mustang on the way. 

Edited By Jon Harper - Laser Engines on 08/12/2017 12:20:14

trebor08/12/2017 12:22:07
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1293 forum posts
155 photos

I got one of those dubro fuel tanks with the extra lip under the fuel bung in my Astrohog, had a few dead sticks which was caused by the weight getting trapped in the front. I now fit stiffer tubing inside the tank.

Jon Harper - Laser Engines08/12/2017 12:27:51
3162 forum posts
129 photos
Posted by trebor on 08/12/2017 12:22:07:

I got one of those dubro fuel tanks with the extra lip under the fuel bung in my Astrohog, had a few dead sticks which was caused by the weight getting trapped in the front. I now fit stiffer tubing inside the tank.

The stuff radio active do is good. i use it all the time

Martin Harris08/12/2017 12:57:16
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7189 forum posts
178 photos
Posted by Jon Harper - Laser Engines on 08/12/2017 12:15:10:
Posted by John Stainforth on 08/12/2017 10:47:48:

Jon, I do the nose up test simply to check that the clunk line in the tank has not fallen off!

Finally, a legitimate reason

I know (and knew before the experiment) that the tank position was very wrong and was more interested in how a Laser would respond to a high-ish fuel head as my current (rather slow) Tempest build will put its 200v carbs fairly low even with the tank relocated as far as physically possible (we discussed its suitability a while back, Jon and decided it should be OK).

The point about the unrealistic needle position is well made but this is a case where a nose up might have made the difference between success and a broken model as it could have revealed the problem before encountering it in the air - although in my case I deliberately positioned the prop hang in a safe position to bring it back dead stick, as a precaution.

My take on the nose up is "why not?" - I have experimented with the sustained level power check and while it seems adequate on a well designed installation, I do a lot of test flights with new models for clubmates with a wide variety of engines and tank installations and trust it to reveal likely problems in the air. My own models get a tweak on the needle if the weather has changed significantly or I've disturbed the setting to replace a cowling but otherwise are simply started, nose upped on the way to the flight line for confirmation that all's well in the plumbing department and flown...

trebor08/12/2017 13:01:33
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1293 forum posts
155 photos

Never heard of them "Radio Active "but I'll have a look yes I think I'm becoming a laser convert. I like the way you can strip them down, even adjusting the valve tappets is a pleasure to do. I bet that back plate can be a sod if you get a really stuck one though.

Edited By trebor on 08/12/2017 13:04:07

Jon Harper - Laser Engines08/12/2017 13:23:31
3162 forum posts
129 photos
Posted by Martin Harris on 08/12/2017 12:57:16:
, I do a lot of test flights with new models for clubmates with a wide variety of engines and tank installations and trust it to reveal likely problems in the air. My own models get a tweak on the needle if the weather has changed significantly or I've disturbed the setting to replace a cowling but otherwise are simply started, nose upped on the way to the flight line for confirmation that all's well in the plumbing department and flown...

I understand the theory, but the test wont actually prove anything. If you flew the model that failed on the ground it would fly fine unless the tank was a mile out as in this case. The problem with the test is that its in people heads as a test that gives 100% concrete results and is THE test for tuning. This idea is completely wrong and it really proves absolutely nothing. This is demonstrated by all the chaps who wave their models around for a bit and then suffer a deadstick on climbout.

The only way to test engine tuning is to fly the model and if there is a question mark over the tuning just maintain a little height, takeoff at less than full power etc until you are sure its ok. At the end of it all, if the engine runs horizontal on the ground, it will run horizontal in the air. Unless you pull into a vertical climb straight away its going to be just fine.

Regarding 'why not', i would say that continuing to promote a flawed and irrelevant piece of modelling folklore is more than sufficient reason to give it a miss. I too do a large number of test flights and have never nose up tested any of them and have never had any quit on me.

Dont bother with it guys, its not safe and it wont help you tune your engines. I know noone will believe me, but its the truth.

Martin Harris08/12/2017 13:52:19
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7189 forum posts
178 photos

I think a lot of the problems are caused by those "chaps who wave their models around for a bit" and I wince when I see someone open the throttle, point the nose up for half a second and pronounce their model fit for flight. In that case, I agree 100% that the nose up check is a waste of time but I see no reason not to do one for a few seconds as a final precaution.

These are just my own feelings borne of experience of a reasonable number of different engines and installations and if anything, I believe I would be more likely to be influenced by your opinion than that of any "club expert" (and I'm probably guilty of being one of those!) I certainly agree with the point that fine tuning must be done in conjunction with actual flight testing but I think we'll have to agree to disagree on this one though - I don't want to disrupt the Laser production line too much!

Edited By Martin Harris on 08/12/2017 13:59:40

Jon Harper - Laser Engines08/12/2017 14:27:34
3162 forum posts
129 photos

I cant help but smirk a little at your post Martin, and i mean the following in jest but....

You know its pointless, know it wont prove anything and that there are better ways to do it.....and yet stick with it anyway and advocate it as a good thing. Seems strange to me

Im not having a pop at you at all, its something i see all the time within my work here. I can explain the nose up test, or fuel choice, or not running the engines rich, or running in the engines the right way and not the 2000rpm rich for 3 weeks way, or where the fuel tank has to go, and everyone agrees and says 'oh yea thats really great and very interesting'. They then go and buy some crap fuel with 30% castor, run the engine slobbering rich with the fuel tank somewhere up in orbit, then phone to complain the engine isnt working correctly and they dont know why! I have even had a modelling magazine refuse to follow my running in instructions on the basis that 'old habbits die hard'. They then published the article stating that they ignored the instructions.

Its quite frustrating, why wont you blokes all do as you are told?

On a serious note though, my comments and posts about this stuff are intended to try and help everyone get the most out of their engines and their hobby. I understand that 'we have always done it this way' is the mentality that is foremost in the hobby and perhaps i am wasting my time trying to change it. But, the one thing i cant stand is bad advice and if i can give better advice and lead people away from outdated and dubious practices then i will try to do that. Modelling has changed, technology has changed, and yet many of our practices date back to the 50's. Its time to update ourselves a little.

When it comes to the nose up test my objections are simple. Its dangerous to be waving a model around at full chat in the pits. Its not representative of a flight condition most models will see and is not an accurate measure of the state of tune of an engine. It also leads to unnecessarily rich mixtures which not only give their own reliability problems, but also waste fuel and make the model far dirtier than it needs to be.

I have not done a nose up on any model in a decade and have never had any engines let me down. Both as a modeller and as an engine designer i dont recommend this test as it really serves no purpose.

Ron Gray08/12/2017 14:51:32
335 forum posts
101 photos

100% behind you Jon on this one and you are not the only engine 'maker' to say the same thing. In the last couple of weeks I've been chatting to one who, had it not been for a different accent, I could have sworn was you "start the engine, lean it out and get it up in the air, see what it does, take it from there, that's proper running in"

Percy Verance08/12/2017 14:55:45
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5713 forum posts
108 photos

trebor

A chap I once flew with used to have problems with his clunk going forward in his tanks until he replaced most of the tube inside the tank with a length of brass tube, keeping just two pieces of silicone for where the clunk and tank bung are. No further problems.

Not tried it myself - never had any issues, but it worked for him.

Martin Harris08/12/2017 15:34:22
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7189 forum posts
178 photos
Posted by Jon Harper - Laser Engines on 08/12/2017 14:27:34:

I cant help but smirk a little at your post Martin, and i mean the following in jest but....

You know its pointless, know it wont prove anything and that there are better ways to do it.....and yet stick with it anyway and advocate it as a good thing. Seems strange to me

Well, I know I was going to let it rest - but that's not what I said. I agree the primary tuning method is done level and fine tuned by air testing but the nose-up gives a last check that nothing has changed since the last flight, either in tuning or plumbing. I don't do them on subsequent flights on the same day unless there's been a nose over or other reason to suspect something has changed. I have certainly picked up numerous plumbing problems over the years as a result of performing nose-ups. In terms of safety, we have a 3m safety fence and all nose ups are done close to it and pointing away from the pits so there's little risk - a little thought will allow safe nose-ups at most locations.

In all other matters, I'm very happy to adhere to your running in and installation advice - Lasers are constructed differently to most, if not all other model engines and if you don't know the best way to treat them...

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