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Laser Engines - Technical questions

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Frank Skilbeck03/07/2020 17:21:45
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4751 forum posts
104 photos

Sorry if this has been asked before, but what's the thread in the outlet of a Laser 150 exhaust. Thanks.

Jon - Laser Engines03/07/2020 19:07:13
5560 forum posts
270 photos
Posted by Frank Skilbeck on 03/07/2020 17:21:45:

Sorry if this has been asked before, but what's the thread in the outlet of a Laser 150 exhaust. Thanks.

m14X1

David Davis12/07/2020 14:19:16
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3782 forum posts
724 photos

When bolting engines to wooden engine bearers I usually use high tensile steel socket bolts ( Allen bolts,) into captive nuts.

I am fitting a Laser 80 to the DB Sport & Scale Auster. I don't think I have sufficient high tensile socket bolts for the job but I have plenty of stainless steel socket bolts. Could they be used or would I be better off buying the high tensile variety?

Ron Gray12/07/2020 14:27:13
2235 forum posts
978 photos

SS will be OK David. If you snap those through vibration you've got a serious problem!

Bob Cotsford12/07/2020 14:47:19
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8637 forum posts
483 photos

There's an argument for not using high tensile, in the event of an arrival softer bolts will be more likely to give rather than snapping off the engine's mounting lugs.

Ron Gray12/07/2020 14:57:51
2235 forum posts
978 photos

thumbs up

Jon - Laser Engines12/07/2020 17:24:43
5560 forum posts
270 photos

not a fan of wooden engine mounts. they should be cut out and replaced with a glass/nylon jobby

Chris Walby12/07/2020 19:06:21
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1276 forum posts
315 photos

Weekend Laser Pro (lower oil content) update as if it needed any update really wink

Saturday.

  • Laser 180 pulling a YAK around. Very minor adjustment of the main needle followed by 4 flights no issues and I think its bedding in a bit or there is a bit extra in the way of engine performance
  • Laser 70 whizzing a Acrowot all over the sky. Initial warm up and minor adjustment (as you do) and then 3 flights with no issues and running sweet.

Sunday

  • Laser 70 twins in a Dual Ace, no initial adjustments then 3 flights and on last flight something sounded a little off. So Mr Numpty landed and refuelled then started both and held them at WOT for a few seconds where promptly the port engine died, stopped the starboard, restarted and set the port engine up gave it a little adjustment (should have done that at the start). Then proceed to start the starboard and go flying...you know what I should have done! So because I had not taken the time to set the Starboard engine I was rewarded with a dead engine, needless to say it was a bit exciting and the other 70 performed faultlessly to get me back on the field safely.

Summary

All of that and only used 1/4 gallon, hardly any post flight cleaning and great performance its a thumbs up from me!

Martin Harris12/07/2020 19:25:21
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9409 forum posts
255 photos

Something niggling at the back of my mind...

You had 3 successful flights and then the engines needed adjusting? Any idea why that would be? I would have thought that any adjustments should have been required during the first tank of the new fuel...

Could the new fuel be flushing through oil residue in the carb or is something changing mechanically - valve clearances, ring sealing, something else?

Chris Walby12/07/2020 19:45:52
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1276 forum posts
315 photos

I have flown the Dual Ace on the new fuel before, it was just my fault for not doing the individual engine warm up and main needle adjustment (as I should have) instead of warming both up and holding WOT for a short time before flying.

I follow Jon's advice and don't WOT them on take off and for the first couple of flights only used WOT a couple of times for a brief period. The third and much of the forth flight it was at WOT for longer periods.

Perhaps a product of + 10C ambient increase and they are over propped for the noise test as they only needed 1/4 of a turn or less to get them spot on. Moral of the story...follow manufacturers instructions.

Jon - Laser Engines13/07/2020 08:22:56
5560 forum posts
270 photos

Its not uncommon for engines to change a little over the day, especially if they have not been run in a while as it can take a little bit of time for the rings to fully loosen up, any oil accumulation in the crankcase needs to be spat out, oil residue in the carb can also take a little time to wash out (especially if its castor!).

I dug out my twin 70 powered model a few weeks ago and it took 3 or 4 flights to fully dial it in as i changed fuel and the engines had not been run in about 5 months

Eddy Dale20/07/2020 19:03:02
1 forum posts
Posted by Jon - Laser Engines on 15/06/2020 09:36:19:

Ha! True enough, i love testing the 240v's on a 16x8 and watching the revs rise. So often the engine sits there at 9800-9900 and i am willing it on to the round 10k!

Those revs are not ideal for a warbird though as you get that awful prop whine...unless i fitted a 1.7:1 gearbox on the front. 9000rpm on the engine, 5100 on the prop. Normally a 17x8 2 blade will do about 9000, with some maths i recon you could swap 17x8 2 blade for 21x14 3 blade using a gearbox like that. Sound like fun? who would pay £150 for a gearbox as an upgrade part?

Edited By Jon - Laser Engines on 15/06/2020 09:36:45

Hi Jon,

I really hope that you will start producing gears for your engines and would easily pay 150£ for one.

Think that the option of installing gear on the engines will increase the popularity a lot. Many people would be interested in the possibility of putting large scale propellers on their warbirds operating on lower RPM’s. I guess the sound will be sweet too!

Do you have any pictures or videos of a prototype?

kevin b20/07/2020 19:21:36
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1853 forum posts
146 photos

Looks to me like someone will have to gear up for mass production of large 3 blade props ! devil

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