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Member postings for Jon - Laser Engines

Here is a list of all the postings Jon - Laser Engines has made in our forums. Click on a thread name to jump to the thread.

Thread: New Laser engines. What do you want?
18/09/2018 13:04:38

Sorry for the absence, i was on holiday and had other things on my mind (see photo). I also had no internet or phone signal. It was lovely!


In any case, this thread ran its course and has essentially been closed. The technical questions thread is for...well, technical questions.

Thread: saito 125a fs
12/09/2018 21:12:05

15x8 is a good place to start with a 120 class engine. Saito typically like to rev as well so run on on 14x7 or 15x6 i would suggest

Thread: What engine
11/09/2018 23:29:01

i would say 100-120 would be plenty. A 155 is likely to be a little excessive i think.

Thread: Seagull Mosquito weight
10/09/2018 11:56:01

I couldn't agree more. Warbirds aren't difficult to fly but they are different and require a very specific style of flight. They really don't appreciate being slapped about the sky. Its more about being smooth and flowing. Just nudge the model where you want it to go.

Alas its sometimes easier said than done as the learning curve is usually pretty steep and often its all over before a new warbird pilot has realised they made a mistake.

The more I see posts and comments about this model the more I am tempted to get one. My current sport twin is ok, but its not really setting my world alight. I could take the two Laser 70's out of it, along with the radio, and be up and running pretty quickly.

Might have to have a clear out and see how the finances look...not to mention the space!

10/09/2018 10:39:10

to help out with the swing try some different props. 12x6 would probably be better suited to the model anyway and may give less swing. Another thing is that if one engine is a little slow accelerating this could, and most likely is, causing the problem. nail down all your tuning and slowly apply power. I am always very slow getting the power on with a twin. I usually do just enough to get it rolling, then coax the tail up, then add looks cool and covers off an engine bogging down.

Also, nice job proving that loosing an engine on a twin is not the non recoverable disaster it is often claimed to be

Thread: OS 120 FS and 82 db
08/09/2018 10:30:40
Posted by Peter Jenkins on 07/09/2018 20:11:37:
Thanks for your experiences guys.
Jon, I flew a similar size Spit with an OS 90 and that was marginal on power. Ask any fighter pilot whether he has enough power and he'll always want more!

In full size that's true, not so much for models. Propeller selection and flying style can often influence the required power. In this case, a 9lb mustang of 64 inches, an 80 or 90 propped on 14x7 or 15x6 would be more than sufficient.

Models can be really awful to fly if overpowered.

07/09/2018 06:40:58

if its a 120e you are likely to struggle, if its the surpass you should be ok.

Its pretty ott for the mustang though. I usually recommend our 80 for that model so any 80-90 should be plenty. A friend is using an os 120 in a 72 inch spitfire and is not short of power.

Thread: Laser 180 Petrol
06/09/2018 10:21:10

Following the back and forward with Ron trying to sort out his issue I will be rearranging and re writing some of the section in the instruction. Part of the point of this beta test is to give the instructions a test drive and as they have been found to be not 100% clear I will be making some changes.

I also suspect that Ron has been suffering due to the lack of the proper choke that will come with the engine. I will be sending this too him asap.

Air bubbles are the engines arch nemesis and clearing the fuel system of air before starting is very important.

Thread: Seagull Mosquito Laser build
05/09/2018 07:56:08

when setting up twin throttles I make sure the throttle arms on the carbies are in the same place, and obviously make sure the servos match. All I do then is connect the throttle rods up with the servo and engine held at full throttle. If the carbs are open against the stops they have to be both exactly the same.

I then nip up the adjustors and im done.

Once the engines have run I may then screw/unscrew the clevis at the engine end a turn or two for fine tuning but in general I tend to keep things simple.

Thread: OS 120 E four stroke Engine
04/09/2018 23:16:59

Don't forget enya. if you can find a 120R they are savage monsters. Not especially refined I would say, but power in spades.

Thread: Precedent Stampe 1/4 Scale
04/09/2018 12:16:39

looks nice. at +6/-3 g loading it should be aerobatic too although i doubt its certified for it being a microlight

Thread: Laser Engines - Technical questions
03/09/2018 23:54:34
Posted by Rob Tothill on 03/09/2018 22:32:14:
Thanks Jon,
It is an APC.

Should there be a gasket for the rocker cover? It doesn't have one and seems to be leaking a bit of oil. I'm not bothered about the dripping oil if it won't cause any problems.

it should seal on its own but if not clean it all with meths and give it a little wipe of silicone sealer

03/09/2018 15:33:04

dont get too crazy about valve clearances guys. as long as they arent stupid the engine wont really give a hoot.

If you dont have a feeling guage then tighten the adjustor down until their is no play, then back it off 1/8 turn and nip up the nut. You should be able to feel a little bit of play, if so, its all good.

15x6 apc (??) at 9k is fine for a 120.

Manish, to be honest im not sure. It could be fuel draw, could be turbulence, could be your fuel or something else. If its over revving i would expect it to behave as you describe..there's loads of reasons. Its not something i have ever noticed and if it runs fine in the air then dont worry about it. I would have test run the engine before i sent it so if something was wrong i would have seen it.

Thread: What cc petrol engine ?
02/09/2018 17:29:16

I would agree with Don. A DLE 20 is almost exactly the same as our 23cc 150 and slower than the 25cc 155.

It makes an awful noise though. Get an after market exhaust for it as its really not at all pleasant without it.

Thread: Laser Engines - Technical questions
30/08/2018 21:23:47
Posted by Martin McIntosh on 30/08/2018 15:05:30:

Not a question but a trap I fell into with my 155.

Found a Xoar 18x7 at the nats so decided to try it. Prop nut well tightened but after about 8 mins there was a nasty sound as though it was loose. The motor idled normally so I landed it for a look at the problem back home. The nut was still very tight but each time I attempted to start up it was thrown off. The washer was locked tightly onto the shaft and took quite some removing. The prop rear was burnt, with the burnt bits embedded into the driver.

It turned out that the prop was thinner at the root than those previously used so that the nut was only tightened onto the unthreaded part of the shaft and not really grabbing the prop. A thicker washer cured it.

props sure do make a weird noise when spinning slightly slower than the engine they are attached to. You get a weird optical effect through the blades too

29/08/2018 13:36:26

It sounds like there is a piece missing from your needle. They should have a washer for the spring to push on as shown below.


Thread: Seagull Mosquito weight
27/08/2018 23:41:34

I would set the elevator rates as low as you can Chris. In general I take the low rate from the kit instructions and set my low rate about a bit lower and high the same. With a recommendation of 15 I would probably go for 10 and 15. I work on the basis that I should have my bases covered with this at least for the maiden flight. I start with high for takeoff but take great care to not yank at the stick until well clear of the ground. Its also my standard procedure to belly land somewhere soft in the event that the model is 'uncontrollable' in pitch. Its something I have done only twice but its better to do that than try to land and smash the undercarriage. I usually find that most warbird manuals have way too much elevator deflection so ignore them now. As you have a recommendation from Richard of 8 then I would use 8 low and 12 high? something like that.

Personally I don't use any expo until the model is flown and even then its rare I use any and I have never found the need to use more than 10%. I agree with Richard that the argument about whether to use it or not could rage for a week so best not to get into it. I think his recommendation is pretty sound, if you use it normally then use a bit, if you don't then don't.

As for balance, I would go right way up as Richard suggests with gear up and no fuel. This is going to be the model tail heavy condition the model will see so even if its a shade tail heavy two tanks of fuel and lowering the gear will fix it.

I would suggest getting the gear retracted asap on the maiden though. Get the drag off the model, clean up the airframe and go from there.


Edited By Jon - Laser Engines on 27/08/2018 23:44:09

Thread: ASP settings query
27/08/2018 22:07:08
Posted by ASH. on 27/08/2018 20:00:58:
"Remember too that rpm will drop as the engine heats up..."
Why is that Jon ? I would like to know the technical reason for that? Is it because the chrome plated cylinder expands?

yea the whole thing expands, valve clearances go larger, the fuel charge entering the cylinder is warmer/less dense. There are many reasons

27/08/2018 18:18:43
Posted by Ronos on 27/08/2018 16:19:19:

Hi Jon ,it's Masters Airscrew K .

Those will be a bit slower so mid 9's is probably fine

27/08/2018 15:54:44
Posted by Ronos on 27/08/2018 13:35:57:
13x6 Jon.

they should be revving like crazy if they are APC. I expect 10000 out of that prop on a laser 70 and a friends OS70 was slightly up on that if I recall. Another friend has an SC70 and he used 13x7 JXF props but I cant recall the rpm. I think it was mid 9000's

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