Laser 310FT

[Adrian Smith 1]

Cracking plane,Ron. I especially liked the video clip 😀

[Paul De Tourtoulon]

Now that's a cracking sound, Ron.

[Ron Gray]

It does sound nice Paul but a bit on the loud side, hence my in vid comment about a larger prop. As you would expect it is a completely different sound to my in-line Lasers. I could also fit larger silencers, it comes with the dumpy ones, to see if that helps or maybe just limited the amount of WOT use!

[Jon H]

Its got plenty of grunt that is for sure. What prop are you running Ron? 20x8? if so i would try 21x8 or maybe 20x10, depends on if speed or thrust is more important. 

 

I also thought it was pretty quiet in the video, on the exhaust side anyway as prop whine was evident at high power. I also agree the tuning is a bit out on the slow run as it sounds great at higher power but one cylinder seems to be along for the ride at low power and isnt contributing much. I would lean the slow runs a bunch more and see how you get on. 

[Ron Gray]

For this style of ‘plane I think thrust is the No1 choice for me!

Running a Metz 20x8 at the moment but have also got a Falcon 20x10 prepped (drilled). I’ll have to recheck my prop drawer to see if I have a 21 as that would, to me, seem to be the logical next step considering the tip noise. I do need to lean off one carb for definite as, if nothing else, there’s some mess down one side of the fuse but it maybe both need a bit of a tweak, other giveaway is it drops revs ever so slightly when I remove the glow driver.

 

On the power front, bearing in mind that this was previously powered by a DLE55, I tried a vertical up line and it’s fair to say that it’s ‘unlimited’, putting it into context I had to stop it climbing at approx 1000’, no rocket ship but not too bad at all. TBH this motor has exceeded my expectations!

Edited April 26, 2023 by Ron Gray

[David Hazell 1]

It sounds absolutely EPIC. Out of interest, what's the power like compared to the 2 stroke petrol engine you had in it?

[Ron Gray]

37 minutes ago, Ron Gray said:

On the power front, bearing in mind that this was previously powered by a DLE55, I tried a vertical up line and it’s fair to say that it’s ‘unlimited’, putting it into context I had to stop it climbing at approx 1000’, no rocket ship but not too bad at all. TBH this motor has exceeded my expectations!

@David Hazell 1as per my post above, but to clarify, I would say that it hasn't got as much power as the DLE55 but it isn't that far short. I expected it to be quite a bit down on power and had resigned myself to the model being capable of 'lazy' aerobatics with loops having to be performed with a slight dive to start with. But as you can see from the vid, there is power to spare and loops are from the level. In fact if you listen to the video I only applied WOT I think 3 times! 

[Ron Gray]

Just looked in my prop drawer and I have 19x6, 19x8, 19x10, 20x8, 20x10, 22x10, 22x12, 22x13, 23x10, 23x12 but no 21!

[Ron Gray]

Oh and another interesting fact, based on a 7 minute flight (plus 2 minutes from pits to stopping motor) the motor consumed approx 340cc of fuel, which equates to approx £1.75. In my book that's pretty good.

[David Hazell 1]

Sounds a whole lot nicer too...

[Jon H]

28 minutes ago, Ron Gray said:

Oh and another interesting fact, based on a 7 minute flight (plus 2 minutes from pits to stopping motor) the motor consumed approx 340cc of fuel, which equates to approx £1.75. In my book that's pretty good.

 

Yea this suggests its running pretty rich somewhere. The 300v in my P39 uses between around 350ml on a 10 min (takeoff to touchdown) flight plus a few minutes of faff at the beginning. Running my 360 powered sea fury the other day i was looking at probably around 400-450 on a 12 ish minute flight plus faff, and it was mistuned on one cylinder so that one drank a little more than it should. 

 

In any case, if you end up with say 350ml/10mins after a tweak you are down to about £1.50 a flight, depending on the cost of the gallon as this changes a bit. In any case, this shows why i am still not sold on petrol as a petrol version of the engine would be a good £200 dearer at least, which works out to about 133 flights burning glow fuel before you break even. 30 flights for the engine in a year (3 flights a day, flown 10 days over a full year or 2 flights on 15 days) its nearly 4 and a half years of flying to break even with a petrol engine that hasnt flown. All in a model that was probably over 2 grand if bought new? I just dont see where the alleged cost savings of petrol come from within a time frame that makes them relevant, at least on an engine of this capacity. 

 

Anyway with your slow runs Ron i suggest you lean both an 1/8 turn, firewall the throttle, and if the engine picks up do it again, and again....until one cylinder gives out and wont accelerate any more. When you hit that point richen the dead one 1/8 so its picking up again and just keep leaning off the other one until it does the same. The slower you move the throttle the leaner you can go and the more fuel you save. Its why i dont recommend people use lightning fast servos for throttles and if one is used, a throttle delay or servo slow can be employed. servo slow on throttle can also be a good idea on a twin engine model as you might firewall the engines in a panic and have one pick up before the other causing a spin if its just at the wrong time. A 2 second servo slow isnt much, but it would give the engines a chance to pick up together.

 

When it comes to oil splatter the left cylinder tends to be oilier than the right as crank rotation throws any oil pooled in the crankcase at that cylinder. so it is not a reliable guide to which cylinder is rich. As i mentioned on another thread we tend to try and diagnose things with our eyes and not our ears and this is a big issue when it comes to engine tuning. 

 

 

 

 

[Ron Gray]

2 hours ago, Jon - Laser Engines said:

the left cylinder

From the front or back as you look at it?

[Jon H]

11 minutes ago, Ron Gray said:

From the front or back as you look at it?

 

yea i always assume i am sat in the cockpit

[Ron Gray]

In that case the ‘messy’ cylinder is on the right! But, as you say, it really is down to tweaking and listening which I will be doing tomorrow in the garden. 

Edited April 26, 2023 by Ron Gray

[Jon H]

18 hours ago, Ron Gray said:

In that case the ‘messy’ cylinder is on the right! But, as you say, it really is down to tweaking and listening which I will be doing tomorrow in the garden. 

 

In that case it might be a sign, but i still dont trust it 😉 

[Ron Gray]

Ever since I started to use the new low oil fuel I tend to expect little mess on the underside of a model after a day of flying. In all but 1 of my Laser powered models I now know that when I turn the model over for the end of day clean I will only have to give the undersides a quick wipe down so when I see more than the usual mess I think to myself well maybe there’s something not quite right. I agree that this is not the main thing that I use to determine correct mixture / tuning settings, for that I rely mainly on my ears and the actual performance!

[Martin Harris - Moderator]

I’ve used the same engine in different models using the same fuel and prop/tuning combinations with dramatically different results. My Miles Atwood Special left just the slightest dirty mark around the exhaust outlet whereas the same ASP 180FS deposited Torrey Canyon style slicks under my Yak 54. 
 

I believe oil deposition has most to do with local airflow effects. 

[Ron Gray]

A very valid point Martin therefore cannot be relied upon as a definitive tuning indicator!

Edited April 27, 2023 by Ron Gray

[Ron Gray]

Engine retuned and prop changed to a 20x10 Falcon. This has cut out the erratic mid rev running and has got rid of the prop tip noise but the engine is still rather loud!

 

 

[Simon Bulk]

Hi Jon.

 

The FT310 is really a beauty of an engine! Here are 2 short questions:

 

1. If I see right, in contrast to the instructions of all other Vee engines you use a a Y-Adapter for the fuel supply. So: One Tank, one fuel line, one tank clunck. Right? Why was that changed? Is there anything different in the Twin design that you can easily get rid off the prior solution with 2 fuel lines or 2 tanks?

 

2. Maybe this one has already been discussed in another thread, but: Even though more complex, have you ever considered to built a real boxer FT? So, 2 individual, opposed crank throws?

 

Best 

Simon

[Jon H]

Hi Simon

 

1 hour ago, Simon Bulk said:

1. If I see right, in contrast to the instructions of all other Vee engines you use a a Y-Adapter for the fuel supply. So: One Tank, one fuel line, one tank clunck. Right? Why was that changed? Is there anything different in the Twin design that you can easily get rid off the prior solution with 2 fuel lines or 2 tanks?

 

In testing it was found that the FT and Inline twins ran fine with a T in the fuel line but the V's still refuse. I suspect this is related to valve overlaps between the cylinders on the V. 

 

1 hour ago, Simon Bulk said:

2. Maybe this one has already been discussed in another thread, but: Even though more complex, have you ever considered to built a real boxer FT? So, 2 individual, opposed crank throws?

 

Not really. The engine would be probably twice the price due to the complexity of the manufacture and would offer little over the current design. I intended the FT engines to be super simple 'bolt on and fly' type engines rather than the OS style of trying to make a mini replica of a full size engine so simplicity and cost were high on the list of priorities. This also allows the customer a choice between a flat and a V, at the same price, weighing the pro's and cons of each.

[Jon H]

Another customer using a 310 has swapped his prop from 20x8 apc to 20x8 falcon and reported massive performance gains for the same rpm. I cant test it myself, but that is the report i have been given from the field. 

[Ron Gray]

I'm still running mine on the 20x10 Falcon and, for this model, it's very well suited. I flew it yesterday after tweaking it a little bit and it sounded like the prop was just nudging the prop tip scream so I'll leave it as is! You will be able to judge for yourself on Friday!

[Manish Chandrayan]

17 hours ago, Jon - Laser Engines said:

Another customer using a 310 has swapped his prop from 20x8 apc to 20x8 falcon and reported massive performance gains for the same rpm. I cant test it myself, but that is the report i have been given from the field. 

Falcon props being lighter will definitely show increase in rpm over the composite APC or even the wooden Xoar props. And those extra revs translate to performance increase . I have witnessed this when on my 35/50 cc petrol powered models I changed from Xoar to Falcon      

[Jon H]

5 hours ago, Manish Chandrayan said:

Falcon props being lighter will definitely show increase in rpm over the composite APC or even the wooden Xoar props. And those extra revs translate to performance increase . I have witnessed this when on my 35/50 cc petrol powered models I changed from Xoar to Falcon      

 

I am told revs remained the same as the apc but performance increased. RPM is not a defining factor when it comes to thrust and a slower revving prop of the same diameter and pitch can offer greater performance than a high revving one. Classic master airscrew props are a prime example as they rev quite well but give poor performance in the air. The physical weight of the prop will not make any difference to RPM either but will impact throttle response.