Laser Engines development.

[Jon H]

Thanks for the input. It seems the dumpy one is getting the general vote and below is a photo of the old style i am currently using. We can tart them up a bit and make them a little more effective as well. They can be rotated to point in or out too so should satisfy the Aerotec's AWXL. 

 

The thing with this is it will always be a compromise. Flexi might suit the AWXL, but will it be any good in a cub? It would certainly be a pain in my wot4 with loads of extra work for no read advantage. I cant cover all the bases with one solution so i wont even bother trying. I just need it to be functional enough in most applications and i think we have that now. 

 

Chris, we used to supple flexi pipe and these plug in exhausts but it all died a death for numerous reasons. One of the main ones was that it didnt clip together like lego and required cutting and soldering and all that. With ARTF dominance modellers with these skills are in the minority these days and combined with other issues they became more hassle than they were worth. Its not a criticism of anyone, just the way it is. 

 

 

Edited February 1, 2022 by Jon - Laser Engines

[Aerotec]

If we can use some silicon tube to extend that outlet then agree this is likely the simplest and most cost effective solution. With some alternative options at an extra cost being useful too. Thx!

[Nick Somerville]

I remember those little silencers as had one in my first Laser engine; a 75 in an Acrowot of course! The cost of the current Laser silencers and exhaust extensions are far below that of competitors offerings btw. If the range can be extended to include flexi pipe extensions and any other options that would be just great. The flat twin looks superb and cosmetically the engraved crankcase is very appealing, though it will buried in a cowl and most likely will only be appreciated by the owner.  Will there be a 300 flat twin?

[Ron Gray]

Dumpy for me please, I’ve got them on my old 150v twin and they aren’t too bad at all.

[steve 1]

For my FT200, I would have dumpy plus (being greedy now) just the header stubs so I can make my own silencers as I did with my lavochkin, if you started doing the flexi again that would be great.

[Jon H]

Aerotec - silicone tube should survive on engines this size. Above 120 it just toasts it. 

 

Nick - Yep, 300 on the cards hopefully before summer. 

 

Steve - we can sort out stubs either way if you want to make your own stuff. We might not be able to get more pipe as they seem to only sell it in 300m rolls now and we only used about 20m a year ? 

 

 

[Solly]

Mick Reeves used to supply flexipipe with Laser stubs, I think he still does.

[Jon H]

I fired up the 200 using the dumpy exhausts and an 18x8 classic master prop. While not the most accurate recording device ever made, the noise app on my phone recorded 84db at about 1 foot away. 

[Ron Gray]

Good enough for me!

[Aerotec]

Sounds like we are good to go then! ?

[Martin Harris - Moderator]

I suspect your app may not reflect real world calibrated meter measurement. While the silencing may be effective, those props give off several dB just lying on a workbench in my experience!

 

Your measurement equates to approximately 57dB at 7m…

[Martin McIntosh]

Tried a MR one and it would not fit under the clip.

[Martin McIntosh]

Even reasonable noise meters are only within 3dBa (twice the volume) as I found out to my cost a couple of times. In 1970`s F3A we soon stopped measuring at 10m because the noise on a windy airfield was more than the motor plus prop. so changed to 1m which was much more accurate but I cannot remember the max. figure. The pipes plus home made silencers on the end were very effective, with most of the noise from the prop. We even went down from 11x7 wood to 9 3/8th three blade GRP which gave 6dBa below the limit, albeit with rather less thrust.

Never even taken my new noise meter out of the packet because I do not want my club to get any ideas.

Sorry to be off topic a little.

[Andy Stephenson]

Martin,

 

It was 110dB at 1m for F3A, I don't know how that compares with the usual 82dB at 7m for club flying.

[Paul De Tourtoulon]

3 hours ago, Ron Gray said:

Good enough for me!

Not enough for me,,,,

 

Quote "my phone recorded 84db at about 1 foot away. in your car with the doors closed,"  or at Idle,,,,,,,?

[kevin b]

My advice is to sell the engines without a silencer and offer the various options separately at their respective prices.

Most people buy Lasers to fit in scale models, so there is often an issue with the exhaust anyway.

Let's face it. Laser engines are already cheaper than their competitors and they don't supply silencers with their engines.

[Martin McIntosh]

Thanks Andy, it was a pretty strict limit which was not easy to achieve. Waste of time testing at club level with wind, short grass, long grass, concrete or tarmac. to contend with. The human ear is best.

[Ron Gray]

1 hour ago, Paul De Tourtoulon said:

Not enough for me,,,

Oh well, I suppose that lost sale will really dent the annual Laser Engine's sales figures!

[Martin Harris - Moderator]

3 hours ago, Andy Stephenson said:

Martin,

 

It was 110dB at 1m for F3A, I don't know how that compares with the usual 82dB at 7m for club flying.

93.1 dB

[Jon H]

5 hours ago, kevin b said:

My advice is to sell the engines without a silencer and offer the various options separately at their respective prices.

Most people buy Lasers to fit in scale models, so there is often an issue with the exhaust anyway.

Let's face it. Laser engines are already cheaper than their competitors and they don't supply silencers with their engines.

 

These are aimed squarely at the artf extra 300 etc crowd. The whole point is to offer an engine that is easier to use and just drops into these sorts of models without any mods so i need it to be a one lump drop in sort of job. 

 

I have decided on the exhaust setup now and just need to make one up and test it. 

[Paul De Tourtoulon]

16 hours ago, Ron Gray said:

Oh well, I suppose that lost sale will really dent the annual Laser Engine's sales figures!

Not yet, it has woken me up so now taking my Laser powered DVII out this afternoon for a flight,,,

[Ron Gray]

There's still hope for you then!

[Robin Colbourne]

23 hours ago, Martin Harris - Moderator said:

"While the silencing may be effective, those props give off several dB just lying on a workbench in my experience!"

Martin, a genuine LOL from me when I read that! ???

[Paul De Tourtoulon]

5 hours ago, Ron Gray said:

There's still hope for you then!

yes I think that I have fallen in love ' again", after flying it,,,,,?

[Jon H]

One of the people after a 200 flat was curious about what the biggest prop was he could use. Curious myself i whipped out a 22x6 cheapo nasty prop, a 20x6 tunigy scimitar prop, 20x6 aerostar, 20 and 22x8 APC props and got testing. 

 

Performance figures as follows. 

 

APC 20x8 - 6800rpm   (identical to the V and I) 

APC 22x8 - 5600rpm

Aerostar 20x6 - 7700rpm (20x6 benchmark RPM 7200 for 200v using good quality prop like menz/falcon etc) 

Turnigy 20x6 - 6300rpm

Cheap 22x6 - 5600rpm. 

 

The above proves a few things and the most obvious is that prop quality makes a big difference to the performance. The 20x6 props are a prime example and only air testing would reveal which is the better prop. The normal expected performance 7200 on a quality prop so the fast one could be spinning its power away while the slow could be moving loads of air and doing the job. Equally, the slow one could be as aerodynamic as a house brick so its runs slow. Having used the aerostar before i think it runs fast and spins some of its power away, and the tunigy is a bit of a house brick. 

 

Given the performance of the engine and how it handled i think 6000rpm will be the recommended low limit but 5500 is the absolute low. In the case of the chap asking the question he wants it for a sopwith pup so a more efficient brand of 22x6 running around 6000 would be fine for him. 

 

When i build the next batch i will retard the inlet cam timing advance by a tooth on one of them and see how that performs. On large loads the needles get a little vague so tightening that up would help with these larger props. That said, it was really windy today and that didnt help. 

 

Anyway, it sounds a little like this.