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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: Flaps
16/05/2020 20:20:53

I have a 72 inch piper Tomahawk and i have about 45 degrees of flap. It really helps with the landing and due to its massively long takeoff run its the only model i have where i use a small amount of flap, mayb 20%, for takeoff.

Thread: Spitfire retracts
16/05/2020 17:39:46

I used the just past centre trick on a retract servo once. I forgot all about it until you mentioned it. I cant for the life of me remember what or why.

I had also not come across proportional retracts before.

As i said before, i always use air retracts as i have just found them so reliable. The electric retracts on my sea fury cause me constant problems

Thread: Flaps
16/05/2020 17:35:48

I have flaps on all of my warbirds and i essentially look for as much flap as i can get. With a warbird i am mostly looking for high drag as i want a reasonably steep approach and all that drag keeps the speed under control.

If i fly a model, and it feels like i have too much flap angle then i can always take it out later. I also try and use a variable slider when i can so that i can feed in more/less flap as i need it.

In general, no flaps on takeoff. You dont want the added drag and given our models have high power/weight you might as well go flapless.

Be aware of the added drag when landing, pull the nose up a few degrees and some models will stop dead almost right away. Be aware too that you might need an elevator flap mix. Again, it varied depending on model but in general lowering flaps causes a nose down pitch, especially if you have retracting gear as well. However, if your model is very light (like a funcub) and essentially has no need for flaps other than for fun, the model will pitch up with flap deployment. The same is also try if you fly too fast, obviously.

Which models are you building?

Thread: Precedent Stampe 1/4 Scale
16/05/2020 13:35:31

it goes like a rocket Steve! How much faster do you need it to go? Its not a pitts after all smile p

Thread: Spitfire retracts
16/05/2020 13:30:25

electric retracts are not proportional so you probably cant use a servo slow on the tx or an inline servo slow either as they only have 2 states, up or down with nothing in the middle.

The simplest option would be to use air as, in my experience, they are much more reliable and give you the desired lag

Edited By Jon - Laser Engines on 16/05/2020 13:31:24

Thread: Laser Engines - Technical questions
16/05/2020 01:00:17


Thread: Precedent Stampe 1/4 Scale
15/05/2020 19:35:36

you guys have an awesome field

Thread: Two Wings and a Round Engine
15/05/2020 19:31:16
Posted by David P Williams on 15/05/2020 17:44:24:


BTW his hasn't flown. It has a Saito 180 and he reckons it's not enough power to make him want to try to heave it off the ground. He has other engines to choose from so he's fitting either a 360V or an ASP 400 radial converted to petrol.

tell him to fit the 360v. I have an sc 400 radial and its 6lbs of dead weight. Dont get me wrong, i love the theatre of the thing, but as a power plant the 360v will leave it in the dust. Also, if he has not already spent the cash tell him not to waste money converting it to petrol.

Edited By Jon - Laser Engines on 15/05/2020 19:31:38

15/05/2020 17:09:04

i love the framing up stage. Its just a giant 3d puzzle and after a really short time you end up with something that looks like it will be done in hours. It never is, but it always looks that way!

WIth your fuel tank entrapment problem, could you cut a 'letterbox' through the firewall that was big enough to post the tank though, and then bolt the engine on the front to trap it? The bolts for holding the engine on look a good distance apart so you should be able to squeeze a tank between them??

Thread: Precedent Stampe 1/4 Scale
15/05/2020 17:00:08

Looks great Steve

Your comments about aerobatics dont reflect the performance of my model. Mine needs to really be pulled round to get it to go over the top of a loop and rolls dont need much of anything other than rudder if i remember rightly. I loose elevator effectiveness when slow and my model has a pronounced nose drop when below a certain airspeed. IF you are nose heavy then that is likely a possible cause. I think most of us are flying with a little down trim. One thing i did find with rolls was i didnt use enough power and pulled my nose up too high on entry. I found that once those two massive wings get rolling the drag is massive and i got better results with a flatter roll at higher power. The added drag kept the speed under control so it worked much better. 

I also dont suffer the pitch up on power either. Admittedly, at really high speed i have to hold it down but i dont tend to go that fast. Is it a pitch up with power or a pitch up with speed? if its the latter then its not a surprise, the former suggests some downthrust might be needed.

On the subject of speed, 20x6 is the right prop for the 180 and it should do a fair lick with that. Mine is way faster than scale with the 20x6 and i spend most of my time trying to slow the thing down. I get the same 6700rpm you do so something a bit strange is happening there as the calculated max airspeed at a conservative 7000rpm in the air is still 40mph so its not exactly hanging about.

Edited By Jon - Laser Engines on 15/05/2020 17:02:31

Thread: Who is building what?
14/05/2020 22:27:35

As i have posted on other threads i am still trying to finish off my Hurricane hurri 34.jpg

And making noises in the garden with engines being rebuilt and tested.

Thread: Laser Engines - Technical questions
14/05/2020 17:47:09
Posted by Martin McIntosh on 14/05/2020 17:36:43:

Jon, are we talking about ADMFC re the horses because this is the first I have heard of it. Got their mail yesterday which said that we can go up next week but nothing else as yet.


Oil. All of my Lasers run very clean anyway but may give the 7% a try.

yep. I asked Peter about flying this weekend and was told its going to be electric only. I asked Mick and he told me its going to be at least 2 more weeks

Its not completely the end of the world, i mean i can fly my electric heli, but as its not flown in 3 years you can tell how much i enjoy flying it vs my planes!

Edited By Jon - Laser Engines on 14/05/2020 17:47:54

14/05/2020 17:11:09

Yea i know, horses dont give a rats. The rich people that own them on the other hand demand a 10 mile exclusion zone.

MT Laser 5 fuel is currently 15% oil so you can thin it some for sure. I wouldnt use more than 3/4 gallon though as the ratios get all complicated.

While on the subject of power, i just test ran a 200v. 9400rpm on apc 17x6. Thats 3hp

14/05/2020 16:22:35
Posted by Anthony Scott 2 on 14/05/2020 16:13:38:

Tim, from where did you obtain the low oil content Laser 5, please? I recently bought some MT Laser 5% for my 180 & could only get 15% oil content.

He picked it up from me here at the factory. Currently the fuel is a 'prototype' and MT are not producing it commercially.

We need to work out a way of distributing it as its sales will be low if its only useful in a laser so the shops are less likely to carry it, also we need a way of making it really obvious that it is only for use in lasers as engine failures may result if used in other brands of engine and this would reflect badly on MT even though its not their fault.

In truth i think OS, ASP and Enya engines would probably be ok on 7% oil. Not sure about saito though. Either way i wont be recommending this low oil fuel for other brands as i cannot guarantee it will work.

Edited By Jon - Laser Engines on 14/05/2020 16:23:02

14/05/2020 15:56:07
Posted by Tim Flyer on 14/05/2020 15:53:04:

Wow 5.6hp is superb for 60 cc 4s !

Perhaps i should video it next time

14/05/2020 15:55:37

Its more that without all that oil clogging up the place you get more air and more fuel. The mixture is also less viscous so i imagine you get better spray from the spraybar. Less sticky oil also gives less drag within the engine, less hydraulic action in the crankcase preventing it breathing.

At idle there is less oil to pool in the plug i would imagine. Its a win win really.

The only note of caution would be to say not to run the engine really rich. If you run the engine slobbering rich the excess of fuel in the crankcase will wash all the oil out, and thats bad.

14/05/2020 15:44:13

Thanks for the report Tim.

Your 200 will be fine on the low oil, i test ran it on that as i do everything else now.

I have noticed that the 100, 200, 180 and 360 especially go like monsters on the low oil fuel. I just test ran some 180's and they were peaking at 9000 on 17x6 props which is massive for a long stroke 'old mans' engine.

The 360v's were really howling as well hitting 8500 on an APC 20x8 which, according to the online calculator, is 5.66hp!

Anyway i will be running all of my own engines on it as soon as im allowed out to play. My club has reopened as electric only as someone had plonked a bunch of horses next door and everyone is paranoid about them getting upset. Apparently i have to wait another 2 weeks :'(

Thread: Has anyone heard from Jeff2Wings ?
14/05/2020 15:38:10

Im having flashbacks to primary school and calling the register.

14/05/2020 09:43:39

J2W's last post was april 13th

Edited By Jon - Laser Engines on 14/05/2020 09:44:04

Thread: Warbirds Replicas P51 Mustang
14/05/2020 09:38:38
Posted by RICHARD WILLS on 14/05/2020 08:57:46:

Sorry Jon , as we established we could not create anything that would stretch into everyone's camp.

Its fine, i was teasing devil

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