Laser Engines - Technical questions

[Andy Stephenson]

Kim,

That's what I was asking but I was talking glow not spark.

[Jon H]

So its ignition timing we are discussing? If so ignition timing in a glow engine is automatic and governed by glow plug temperature. Idle revs means a cool plug and retarded ignition, high speed means a hot plug and advanced ignition with some sort of curve between the two. Changing the temperature rating of the plug shifts the curve one way or the other, although in the case of a 4 stroke you basically get one choice of plug temperature so that is not important. 

[Artto Ilmanen]

@Jon, gents,

 

What might be the recommended Laser for ESM Focke Wulf:

 

Specification: Length :1449 mm(57")

Wing Span :1800 mm(70.9")

Wing Area :56.1 sq. dm 6.04 sq. ft

Wing Loading :103.4 g/sq. dm 33.7 oz/sq. ft

Flying Weight :5.8 kg(12.8 lbs)

Radio :6ch&8 servos Engine :

108 2-cycle 120 4-cycle

 

I was planning to mount a 240V but it is obviously too much.. ? I have been thinking of a Laser 150 or 155 ? (happen to have a Laser 150 sitting on a shelve) Or would a 180 single or some of the multi cylinder engines be a more suitable choice?  No prop hanging intended 🙂 but I hope to find a good compromise between decent scale lake vertical performance  & wing loading.

 

thanks, 

 

Artto

 

 

fockewulf_fw_190.pdf

[Artto Ilmanen]

46 minutes ago, Artto Ilmanen said:

@Jon, gents,

 

What might be the recommended Laser for ESM Focke Wulf:

 

Specification: Length :1449 mm(57")

Wing Span :1800 mm(70.9")

Wing Area :56.1 sq. dm 6.04 sq. ft

Wing Loading :103.4 g/sq. dm 33.7 oz/sq. ft

Flying Weight :5.8 kg(12.8 lbs)

Radio :6ch&8 servos Engine :

108 2-cycle 120 4-cycle

 

I was planning to mount a 240V but it is obviously too much.. ? I have been thinking of a Laser 150 or 155 ? (happen to have a Laser 150 sitting on a shelve) Or would a 180 single or some of the multi cylinder engines be a more suitable choice?  No prop hanging intended 🙂 but I hope to find a good compromise between decent scale lake vertical performance  & wing loading.

 

thanks, 

 

Artto

 

 

fockewulf_fw_190.pdf 3.81 MB · 3 downloads

Well,

 

According to another thread the model requires quite a bit of weight on the nose..:( 

 

 

 

[Chris Walby]

Only my opinion, but as Laser only sell 100 or 155 in there current range that and the manual specifies a 120 then a 155 if new. As you have a 150 sitting on the shelf then that sounds the best bet. The FW190 is quite short in the nose then the additional weight of a 150 compared with a 120 (if you could get one) I suspect won't make a lot of difference.

 

The challenge might be installing the engine inverted and achieving  the correct carb to tank height, as there are a couple of options. Install the engine off inverted/even horizontal if necessary or measure up and chop/beef up some wood work to get the tank the right height.

 

The 180 will just make the tank positioning more difficult as its a taller engine and is over powering a 6Kg model IMO

Edited January 25, 2023 by Chris Walby

[Chris Walby]

DLE is approx 820g, Laser 155 is 955g.

 

If lead is necessary then there is not much you can do assuming you have everything (RX/gear batteries, servos and anything else as far forward) as for forward as possible.

 

The alternative is fly it with a rearward C of G (motto forward CofG flies poorly, rearward CofG flies just the once), but realistically that's not an option.

 

The 180 weighs 1240g so its not a lot heavier than the 150/155 and thus I don't think it will solve you lead issue, just harder to install and still over powered. Anyway Zero flew has with the lead and said it was no bother so doe not seem to be an issue. Could ask Zero what the AUW is and that would give you a good target.

[Artto Ilmanen]

2 hours ago, Chris Walby said:

DLE is approx 820g, Laser 155 is 955g.

 

If lead is necessary then there is not much you can do assuming you have everything (RX/gear batteries, servos and anything else as far forward) as for forward as possible.

 

The alternative is fly it with a rearward C of G (motto forward CofG flies poorly, rearward CofG flies just the once), but realistically that's not an option.

 

The 180 weighs 1240g so its not a lot heavier than the 150/155 and thus I don't think it will solve you lead issue, just harder to install and still over powered. Anyway Zero flew has with the lead and said it was no bother so doe not seem to be an issue. Could ask Zero what the AUW is and that would give you a good target.

Thanks Chris,

 

What you say makes sense. I think I could mount the engine horizontally so the tank height should not be a problem?  While I can't find it right now I think I once came accross someone having flown the model with a Saito 150. He said the modle flew well with that engine. I wonder how a Laser (newer model with round head) compares to Saito 150 powewise? Of course with low -5-10% nitro.

 

[Chris Walby]

I mount my Laser 80's into a VQ FW190 and VQ Air cobra horizontally because the cylinder head will poke out anyway, easy tank position to carb and I don't care what the rivet counters say as it not really scale anyway. Oh and its easy to get to the main needle for a quick tune at the start of the day.

 

Ok not an ESM but a BH, but it demonstrates where the engine can be mounted + that a 120 ASP cylinder head is almost at cowl height so a 150 might just hide inside. 

 

Always worth considering a bit of wood work to get the tank at the right height with the engine inverted, did this with my Hurricane and it might seem a faff but you only do it once especially if you don't have to cut the cowl much. 

 

Model on bench, offer the 150 up, mark where the tank needs to go and post a few photos. 🙂 Sure we will all help to get the install right.

 

 

[Jon H]

A 150 will power the ESM 190 just fine. Even if its 15lbs with the lead a 150 will be ok and provide a decent performance. That said, if you fly it and find you want more power then one of the new FT200 flat twins will be the way to go.  

[Artto Ilmanen]

7 minutes ago, Jon - Laser Engines said:

A 150 will power the ESM 190 just fine. Even if its 15lbs with the lead a 150 will be ok and provide a decent performance. That said, if you fly it and find you want more power then one of the new FT200 flat twins will be the way to go.  

 

Thanks Jon,

 

The FT-200 sounds interesting.

 

I will test the 150 and go from there, though. I believe if I mount the rx batteries (2 x 2000 mah NiMh) inside the cowling I should be good without much of lead. We'll see. 

 

The cowling inside diameter is 215mm so the engine will be completely concealed. I could mount the engine inverted but then the tank height becomes an issue due to the wing preventing installing the tank at correct height. So most likely mounting the engine horizontally is the way to go. At least with some hacking I can then mount the tank at correct height, at least when flying level.  

[Jon H]

Mount the engine on its side or upright, you will not be able to get the tank in the right place if its inverted

[Artto Ilmanen]

5 minutes ago, Jon - Laser Engines said:

Mount the engine on its side or upright, you will not be able to get the tank in the right place if its inverted

 

Thanks- I believe if I mount the engine on its side the tank height will be about correct "top of the tank - middle of the carb" without any hacking when the model is flying level. However, as the tank is in the centerline (left / right) of the fuse and the carb (when engine on its side) is on the right side of the centerline: is this an issue when flying the model on its side, either left or right? 

 

Therefore, if possible should one always attempt mounting a single Laser either inverted or upright, if possible? Any rule of thumb?

 

Or am I just thinking too much? 🤔🤗

 

 

[Jon H]

42 minutes ago, Artto Ilmanen said:

 

 

Or am I just thinking too much? 🤔🤗

 

 

 

A bit! 

 

Side mount, top of the tank, centre of the carb. Job done 

[Artto Ilmanen]

2 hours ago, Jon - Laser Engines said:

 

A bit! 

 

Side mount, top of the tank, centre of the carb. Job done 

 

 

All clear! Thanks, Jon!

 

 

[Jon H]

On the nose weight and c/g thing, i see loads of reports about ESM models having incorrect c/g, they are too tail heavy blah blah etc. I have 3 ESM models currently flying and they are all balanced at or slightly behind the c/g on the plans. All of them fly fine but i use very small elevator deflection and i suspect this is where the people screaming about c/g have it wrong as they are using too much deflection even though the c/g is fine. They add more weight, which fixes the problems in the air, but then the model is heavier than it needs to be and more prone to a nose over. 

 

I have one of these 190s waiting in my build queue but i would not expect it to need more than about 5mm of elevator deflection on low rate and maybe 8 on high? I mean i loop my ESM Sea Fury with about 3mm deflection so you really do not need much at all. 

[Artto Ilmanen]

1 hour ago, Jon - Laser Engines said:

On the nose weight and c/g thing, i see loads of reports about ESM models having incorrect c/g, they are too tail heavy blah blah etc. I have 3 ESM models currently flying and they are all balanced at or slightly behind the c/g on the plans. All of them fly fine but i use very small elevator deflection and i suspect this is where the people screaming about c/g have it wrong as they are using too much deflection even though the c/g is fine. They add more weight, which fixes the problems in the air, but then the model is heavier than it needs to be and more prone to a nose over. 

 

I have one of these 190s waiting in my build queue but i would not expect it to need more than about 5mm of elevator deflection on low rate and maybe 8 on high? I mean i loop my ESM Sea Fury with about 3mm deflection so you really do not need much at all. 

 

This is what I think, too!

 

Btw - maybe not the right thread but I could not find any thread on ESM retracts: I have never had a model with pneumatic retracts. Anyways from what I have heard the ESM pneumatic retracts require some attention to make them work right?

 

Jon / gents, could you possibly point me to right thread or give hints in terms of how to operate ESM retracts with success?  a fellow modeler had bad luck with them but maybe he just did not know what he was doing.

 

thanks

[Jon H]

My ESM retracts have been fine. In both my P39 and La7 i have had no problems. On the few occasions i have lost the air it was my fault with either a leaking fill valve due to dirt, a melted pipe due to exhaust heat or a loose connection to the wing. My La7 is over 10 years old and has suffered about 3 or 4 retract failures with one being due to a servo fail. 

 

Again, i think much of this comes down to people not looking after their gear properly or installing in badly in the first place. That said, stripping the units down and putting them back together with grease in the cylinders and threadlock on the screws is a quick and easy way of checking things look good before you start. 

[Artto Ilmanen]

thanks, Jon!

[Frank Skilbeck]

On a friends YT Bonaza we built (with a Laser 150) we had an air leak inside one of the cylinders, stripped it down and cleaned it and it now works fine. Model was built over 2 years ago but has still to be flown.

[Artto Ilmanen]

@Jon,

 

I happen to have 2 Laser 150s in my Hangar,

 

One is mounted on the nose of my GP Super Chipmunk and is from -08 or -09 if my memory serves me.

 

Then there is another one that I inherited from a fellow modeler who no more flies anything but large models: it has ratchet on main needle? I suppose this is an older one? (This is the one I'm planning for the ESM Focke Wulf)

 

Are they much different from each other? 

 

Do you still have spares for these? 

 

thanks

[Don Fry]

I’m fitting a 160V in a hack. It’s new (to me), and I’m using the supplied bell ended radial mount.

Said mount has eight 4 mm mounting holes. I assume only need to use four to mount it, and the doubling up is to allow convenience in mounting?

[Andy Stephenson]

I have a 300V that only needs 4 bolts, so your 160 should be fine with only 4.

[Don Fry]

Cheers Andy. 

[Scott Edwards 2]

Going on the basis that Jon laughed at me for five minutes for using all 8, I learned that just using 4 will be fine 🤣

Edited February 4, 2023 by Scott Edwards 2

[Artto Ilmanen]

On 15/06/2020 at 12:36, Jon - Laser Engines said:

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

 

Jon,

 

A friend of mine is selling his yellow aircraft Spit MKIV 1/5 scale

 

I believe you fitted yours with a Laser 300v? 

 

I wonder if a 240V could be up to the task for this model? a 240V could be completely concealed inside the cowling. And as I happen to have a Laser 240V sitting on a shelve..  And maybe a gearbox?

 

as a benchmark there is a guy flying one with a Saito FG 36:

 

https://www.youtube.com/watch?v=0K2Z1si9GAo

 

Or does this model just require minimum a 300v to perform scale like aerobatics?