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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: Acro Wot ARTF (balsa) chat
18/12/2018 16:14:29

1/3 should be fine as a flap. I was just using half as a rough guide.

That said your comments about c/g open up a possibility because if you are nose heavy this could mean you run out of elevator authority before you run out of airspeed. This could be why the model is so reluctant to stall and it would also give that uncomfortable feeling of trying to hold the model in the air with the elevator stick. You could add extra elevator movement, but if the model is nice to fly as is i would leave that alone and move the c/g back a touch.

As you suggest yourself, moving the battery back a bit would be a good start and as chris suggests you should hold it off the ground (about an inch up is ideal) for as long as you can before it settles on its own.

On the engine side, assuming you mean 2500-3000 then thats a good idle but i would most certainly aim for the 2500 end of that range. 13x6 @ 10k is also just fine. I was worried you were using a 12x8 or something as that would not be helping you.

18/12/2018 14:30:42
Posted by Jonathan M on 18/12/2018 14:19:14:

Cheers Tim - a good solution.

I've programmed down-flapperons via a swtich into my ARTF Acrowot, but they seem to make the model more floaty rather than slowing it down in light winds. I don't know what the solution is.

 

Edited By Jonathan M on 18/12/2018 14:20:08

If you want to add flaps just cut the existing aileron in half and then remove the inner half. You can then adjust the bevel to allow greater down movement and with some care you should be able to install torque rods in the root and have a single servo in the fuselage do all the flapping. If something gets in the way of the fuselage mounted servo, fitting another servo in the wing should not be too difficult.

Once its all set up set the flaps to come down almost vertical like on a Spitfire. This should add maximum drag with very little additional lift.

Also be careful with flapperons as they can induce tipstall if you go a bit mad with the travel. 

You also say you arent a good power flyer? I assume you mean you are not experienced with power? If so the its possible the additional weight of the model is catching you out. Its also possible your engine/prop combo are not helping either. If you can give details of the engine, prop and idle RPM you have set we might have more ideas to point you in the right direction. 

I only say this as i have flown one of these with an SC 70 and had no trouble slowing it down to land it. 

Edited By Jon - Laser Engines on 18/12/2018 14:34:13

Thread: Nieuport 28 Undercarriage
18/12/2018 14:04:28

If you dont mind a bit of a cheat you can do what i did with my Nieuport 17.

Just assemble the u/c as normal with the 2 V struts and a tie bar between the two at the bottom to make it all rigid. You can then put the axle on top of the tie bar and only bind/solder it in the middle. As its free at the ends you get independent suspension on each wheel. You will need to make some guides for it but 3mm pushrod wire offcuts work well for that. If you want you can use some bungee for looks or to help if the wire is not strong enough on its own.

If i can get a photo of my set up i will

Thread: ASP anybody?
15/12/2018 11:45:17
Posted by nigel newby on 15/12/2018 11:06:02:

A bit like the real ale industry. Big sellers are still around, but it is the small brewer who has more presence in my local. Is it because there are not that many youngsters coming into the hobby? We have the same in amateur radio. In my club at 66 years old I am one of the youngest in my club.

Nigel N

I have been the youngest regular flyer at all the clubs i have been in since i was about 15. Sure there have been those younger that have dabbled, but they are gone within 2-3 years.

Your 'micro brewery' analogy is a good one and i think it reflects the industry well. Many of the models being build are not from established kit manufacturers and guys like fokkerc are offering something different and this is more interesting. A great deal is community driven online with 3d printable stuff freely available for download. Its an interesting time

15/12/2018 09:22:27

i think a great deal comes down to product relevance. These days a 25 2 stroke is barely worth the box it comes in and yet OS used to shift thousands of the 25fp and similar. Enya were the same with their smaller offerings.

As soon as half of your range becomes irrelevant and wont sell you do have a little bit of a problem, especially if you are a large company with large overheads.

Enya also suffered as they didnt really change anything. The 120R you buy today is more or less identical to the one you bought in the late 80's. Again, times have moved on and while the 120R was a brute these days it needs a better silencer and a more accurate carb. Its a shame as i always rated enya as the best of the Japanese engines and currently have about 5 of them waiting their turn.

Also dont forget that in many cases these companies are owned and run by the people that started them, and once those people get to retirement age its pretty much all over. I know this was at least a contributory factor in the demise of solarfilm.

Its not all doom and gloom though. Kolm, Roto, Valach are just 3 i can think of that have recently (ish) started producing engines but they have gone the route of large/multi cylinder engines for the top end of the market.

From my perspective, all i know for sure is that anything i make is gone within a day. The last batch of 12 engines was wiped out in 26 hours from the moment it went online. I just wish i was about to build them more quickly but currently i cant

14/12/2018 23:01:20
Posted by Ace on 14/12/2018 21:59:58:

So back to the OP.

Is Sanye Manufacturing/Machinery Co making or will be making 2s engines - anyone with any more info ??

my understanding is that they are not at the moment although some stock is en route to certain retailers. If what i have heard is true ASP, SC, Magnum and Evolution are all out of production at the moment white sanye sort themselves out

Thread: G/daughter Xmas Pressy Buggy: Sub 50?
13/12/2018 15:31:51

Just noticed that car has a built in battery so it might not be good if you want more than 15 minutes an hour of action

13/12/2018 15:30:00

not sure if this is proportional but it looks it.. **LINK** Im sure a google search will reveal some retailers for it

The other one Ripmax do is the jackal but its a bit over budget.

Thread: Flair Cub
12/12/2018 21:10:17

I would not mix the rudder for a number of reasons and they are all related to the need to use the two controls in opposition.

As an example, you go in to a left turn with left aileron and rudder together, then pull up slightly and round you go. At this point the ailerons return to neutral but you may need more rudder to keep the tail up and keep the turn nice. Even if you dont the outer wing is flying faster than the inner wing and so it may rise with the extra lift and roll you into a steeper bank. As a result you will need right aileron in your left turn to maintain the bank angle you want, with left rudder used to keep the nose tracking nicely round the corner.

Another example would be if you have a cross wind on takeoff. If we assume a cross wind from the model's right i would always hold a small amount of right aileron to prevent the wind lifting the right wing as i leave the ground and flipping the model over. I would also need left rudder to prevent weathercocking into the wind. In this case i would need even more left rudder on the tx as the mix will cancel a bunch of it out. 

In both of these cases you have to use the two controls independently as roll and yaw need to be used in opposition. If they are tied together through the radio this will be impossible to get right.

I couldnt fly a model without a rudder now, i just use it too much.

If you want to practice using the rudder, fly directly away from yourself and rock the wings right/left to about 40 degrees bank angle. As you do it, move the rudder with the aileron stick and vary the amount of rudder you use until you find a sweet spot where it looks right. After that is mastered move on to steeper turns and cross control. By the end you should be able to fly totally flat circles with loads of rudder and opposite aileron.

Its not super easy to see but in this video of the full size there are a number of times you can spot the cross control. https://vimeo.com/7760423

 

Edited By Jon - Laser Engines on 12/12/2018 21:11:55

12/12/2018 18:45:31
Posted by Martin Harris on 12/12/2018 17:05:49:
Posted by SIMON CRAGG on 12/12/2018 17:00:12:

...but need coupled aileron - rudder which is common with this sort of model.

Great opportunity to learn to couple aileron and rudder with your thumbs!

absolutely. Aileron rudder mix should never be used in my view

12/12/2018 16:23:53

I wouldnt change a thing. The model is so docile that the aileron hinge gap wont matter one jot. The 52 will be more than enough, slap it in and just get ready for some stick and rudder fun.

Thread: 3D Printed fuel tanks
12/12/2018 13:51:29

Back to paraffin for parts washing i suppose?

Thread: running in asp 70 four stroke.
12/12/2018 10:21:36
Posted by Engine Doctor on 12/12/2018 09:35:42:

I had a quick look through the threads ,excuse me if it already been suggested but when running a engine in the plane on the ground make sure you have the wings fitted . The wings absorb/ dampen a lot of the vibration and shocks that can otherwise damage the fuselage and tail plane .

Edited By Engine Doctor on 12/12/2018 09:37:21

yes absolutely. I have had many customers complain how much their engine vibrates only to find the model was missing its wings!

Thread: 3D Printed fuel tanks
12/12/2018 08:55:32

I keep meaning to have a go at some tinplate tanks. One question you might be able to answer for me Peter is how to clean its innards afterward? I was going to fill it with thinners or something and just slosh it around to try and wash the flux out. Is there a better way?

Thread: running in asp 70 four stroke.
12/12/2018 08:42:35

Dont be offended Nigel, the PM was not specifically thread related.

One quick bit of info on tacho's.

Dont be tempted to rev chase once you get one. By that i mean dont be too worried about the exact rpm you see and look at the overall picture.

For example, if i tell you an engine should do 8500rpm on a given prop/fuel combo and you see 8450 dont sit there trying to chase the last 50 RPM with a bunch of twiddling. Equally, if you check your engine on a warm summer day and see 8600, then check it again on a freezing cold winter day to see 8400 or even less, dont panic. Engine rpm varies due to atmospheric conditions and colder dense air will usually cause a drop in RPM. It will however give you power power as well as the engine gets a denser charge of air in the cylinder for a bigger bang, and the prop has nice thick air to grab on to. In the summer the air is thinner, engine revs rise, power drops.

The other trap is tuning with the tacho. Staring at the screen for minutes at a time tweaking the needle. Dont do this. When the engine is cold and you run it up to full power you will see a given RPM. After 15-20 seconds the engine begins to warm up and RPM will drop. This could be 100-200rpm on most engines. If you then try to recover this lost RPM by leaning all that will happen is the engine will get hotter and hotter while you fiddle, and will loose more and more RPM as a result leading you to attempt an even leaner mixture. This is not a good idea!

Tune by ear for MAX rpm. Hold that max RPM for 10-15 seconds. If there is no noticeable drop in performance the engine is good to go. Dont bother with a nose up test, its a waste of time. If the engine dies in flight having been tuned this way something else is wrong. Likely tank level or cooling.

When running the 10-15 second power check listen very carefully for any knocking. It will sound like a sharp crack within the overall engine note. Not always easy to spot, but once you know what to listen for its obvious. If you hear any, go 1 or 2 clicks richer on the main needle.

Thread: Hangar 9 P47 repair
11/12/2018 22:55:43

However it ends up Geoff im sure it will fly well after its surgery. Apologies if i went too far down the rabbit hole on the engines front

Thread: running in asp 70 four stroke.
11/12/2018 22:51:38

well then...

Don, thank you for the PM. we are all good.

Regarding model restraints a great deal depends on the construction of the model and how the run is performed. A brief run up retrained by the tail is not going to be a problem to any model built to an airworthy standard. That said, i suspect Percy's comments relate to a prolonged ground run at high power and in that instance some additional tethering is not a bad idea. With my own models i retrain and power check most by the tail, but anything over about 180 size gets some help from me. In the case of my La7, Sea Fury and P39 i more or less hang on for dear life when doing a power check!

Nigel your Bi-fly will be pretty rapid with the 70. I recommend you fly with the 13x6 as you intended and perhaps try a 14x6 to keep the engine from unloading too much in flight. GIve it an hour or so in the air on the 13x6 first though. For run in if you are buying a prop 12x8 or 12x7 will be just fine. I recommend 12x7 for our 70's and they do about 10k on the ground which beds them in nicely. For optimum performance and engine life i recommend you use a prop which gives you between about 8500 and 9500rpm on the ground at full power. Over 10k and its really starting to scream, below 8000 and you are loading it up a bit too much. Once you get into larger engines those RPM drop. A 180 for example would run at 7000-8500, that sort of thing.

a friend has an SC 70 and reports good performance from jxf 13x7 props as well. Might be worth a look. Just make sure you have nice low idle if you are using more than 6'' pitch or you will never slow the thing down enough to land.

11/12/2018 20:11:11

11x7 will be fine as will 13x5 if you have one. You just want something that is a light load and will allow the engine to rev up nicely. Given the cost of a prop, its probably worth buying one. Even if you only ever use it for running in its better to have it than not. You could also fly with it in a pinch and you can use it as a baseline to check engine performance later on.

As the others have suggested a tacho is not needed but can offer useful information so having one in the box is a good idea. Again though, use it for information only and not a tuning tool.

I also agree 3in1 is not the ideal lubricant. I use the same ML70 as is in my fuel when lubing engines. If not available some 2 stroke oil will work fine. You may want inject some into the crankcase as well.

As previously discussed i recommend you run in as follows:

Start at rich (2.5 turns on main needle) setting and run at approx 3000rpm for a minute or so.

Open up to about 5000rpm or half throttle. Again with the rich mix

After 2-3 minutes wind it up to full power and very quickly tune it for about 90% of peak rpm. It should not take more than 5-10 seconds at full power to do this as you are not looking for the perfect tune. All you want to do is get it hot and get the revs up.

Throttle back to half again, and then just play with it for the next few minutes. Check the temperature (too hot to hold, not too hot to touch. 80-100'c is not a problem) with short 5-10 second bursts at full power and plenty of use through the whole rpm range. Give it a few bursts of acceleration from idle to full power as well. You can get a base setting for the slow run as well. usually they need to go leaner. an idle RPM of under 3000 is what you should aim for.

Once you have about 5-10 minutes time on it pinch the fuel off to stop it and let it cool down. It should have half decent compression and is ready to fly. I have been meaning to do a video of me running one of these in but always forget when the time comes.

Depending on the model you want to fly there are plenty of props that are likely to do the job. If you can let us know what model you have for the engine we can recommend props a little better. Its possible you could use the 13x6 from the get go.

Percy, i agree that in general its a good idea to recommend people follow the instructions that came with their piece of kit. Certainly i will be begging on my knees for people to follow the instructions for my petrol engines so i do understand where you are coming from. In this case however i dont agree with the recommendations in the instruction sheet as they are out of date and do not give the best method for running in the engine. They are simply a clone of 30 year old OS instructions which are no longer valid. Were i merely a club 'expert' stood at the back of the field proclaiming one thing or another then your word of caution is well founded. however, i would hope that i have a little more credibility than that and can assure you this is a better way to go

Edited By Jon - Laser Engines on 11/12/2018 20:13:09

Thread: Hangar 9 P47 repair
11/12/2018 12:59:12

Bob - 1A isnt too bad to be fair so i can see your thinking. I will always use 2nd batteries though just because its what i will always do. Its not worth the risk to me.

Geoff - yea i know the type of cut you mean. It comes from fuel building up in the intake and then being sucked through in a blob as soon as you open the throttle enough to pick it up. The fuel 'condenses' out in the intake due mostly to excessively rich mixture on the low end (ASP engines are shipped very rich) but also due to the nature of the design. The rich mixture at idle gradually cools the glowplug and produces that gradual coughing run down we have all seen. The excess the fuel in the charge is 'thrown' out of the air as it goes round the corners in the intake causing an accumulation near the valve. Running the slow run needle as lean as you can will solve this problem but ASP carbs are not super accurate so its not always possible to get it 100% on those engines.

In a 2 stroke the effect is similar but the fuel accumulates in the crankcase as Denis suggests above. The only difference is the fuel does not impede to rod but is instead thrown up the transfer passages once rpm rises enough to pick it up. Again, we see it as coughing and stuttering pickup. Its more difficult to get around the problem in a 2 stroke than a 4 stroke, but again running the slow run as lean as you can will solve the problem almost completely.

10/12/2018 23:34:15

Jon: The engine was a new SC 90 four-stroke (the specified engine is for a 60 2 stroke) and didn't properly recover from the closed throttle run in for my low pass and didn't pick up properly when I opened it up for the climb out. Unfortunately it was heading away from the airfield so a straight descent wasn't safe and my attempt to recover failed. I know you'll say it was because I hadn't set the engine up correctly and I suppose you'd be right but it is a common glow engine problem. I just have a lot more confidence that an electric motor is unlikely to exhibit similar issues and be more reliable.

I assume a Laser wouldn't have been a problem

Geoff

If you would rather use a leccy motor then by all means go ahead Geoff. Its your model at the end of the day.

You are right though. The issue was probably a combination of setup, lack of engine run time, and perhaps an issue with the carb, maybe the wrong plug? The thing that interests me is that even given that you accept a likely setup problem, you go on to say 'its a common glow problem'. I actually agree with the statement, but only so far as i agree that it is a common problem for engines to be set up such that they are prone to failure. I suspect however your intended meaning was more that the underlying principals of glow engines makes them prone to this sort of failure and that is something i would disagree with.

Your point about reliability of electric is interesting too as i have not suffered a random engine failure in over 10 years. And sure i fly a lot of lasers but i fly other brands too without issue. Its easy to set up a laser to be as awful and unreliable as you like, you can with any engine, its not about the brand in many respects. If its set wrong, its wrong and even a good brand will still fall over. It would be like saying electric is unreliable as an ESC caught fire after you constantly ran it 10% over its max current rating with poor cooling. Its the setup that killed it, not the brand or technology itself.

This is not an i/c vs electric, good vs evil post and is not a criticism of you Geoff, and its entirely possible i misunderstood you. I just found your post very interesting the way you worded it.

For your repairs, electric retracts are hit and miss in my experience but the ones bob suggests look good. I would not recommend trying to use anything with too many plastic parts. I would personally use another battery for my retracts. Some of my large sets draw nearly 5 amps so it would be worth checking the ones you use and then making the choice. Im sure Bob is on the ball, but i would not risk it on one of my models given that an extra battery is not very heavy.

One final thing, if you do rebuild it as i/c, perhaps try your laser 80 if you dont have faith in the ASP. If you do, just remember to lower the fuel tank

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