Electronic solutions to modifying glow engines of all sizes to gasoline
09-09-2023, 01:24 PM
#1852
Rather great, of course it fades out ,but say just cruising across the field at 100ft then power and climb vertical to roughly 400ft without a problem, performance is pretty good..only thing a 15x12 is good for is low rpm thrust..
il have a couple more flights today, not sure if to go a bigger prop, it seems good with 17x8
il have a couple more flights today, not sure if to go a bigger prop, it seems good with 17x8
09-09-2023, 02:55 PM
#1853
You likely will see even more vertical performance with an 18x6 and may not lose much if any air speed as compared to the 17x8, Dan. All depends on how draggy the airframe is. At a given peak rpm a larger prop diameter creates more thrust, whereas greater prop pitch creates more air speed. Thing is, if the airframe has a lot of drag, a higher prop pitch/smaller diameter prop may not have enough thrust to drag the plane through the air any faster. I'd definitely try an 18x6, it may just tickle your fancy.
09-09-2023, 03:02 PM
#1854
You likely will see even more vertical performance with an 18x6 and may not lose much if any air speed as compared to the 17x8, Dan. All depends on how draggy the airframe is. At a given peak rpm a larger prop diameter creates more thrust, whereas greater prop pitch creates more air speed. Thing is, if the airframe has a lot of drag, a higher prop pitch/smaller diameter prop may not have enough thrust to drag the plane through the air any faster. I'd definitely try an 18x6, it may just tickle your fancy.
09-09-2023, 11:11 PM
#1855
Senior Member
Thread Starter
You likely will see even more vertical performance with an 18x6 and may not lose much if any air speed as compared to the 17x8, Dan. All depends on how draggy the airframe is. At a given peak rpm a larger prop diameter creates more thrust, whereas greater prop pitch creates more air speed. Thing is, if the airframe has a lot of drag, a higher prop pitch/smaller diameter prop may not have enough thrust to drag the plane through the air any faster. I'd definitely try an 18x6, it may just tickle your fancy.
Mind you, it COULD be necessary to reduce servo-speed a touch on the upstroke of the throttle, due to the larger inertia of the prop: With gasoline, if the throttle opens TOO quick for the acceleration of the engine, mixture temporarily gets out of whack and that can lead to trouble. No biggie, do NOT adjust acceleration problems with the idle mixture, just reduce servo travelling speed to say, 0,5 ~ 0,7 sec, that usually does the trick.
The downside of an 18 x 6 prop is that at idle it functions as a huge airbrake, and you MUST come in on the throttle at landing. My BigLift (the plane in the vid I posted) can maintain a 45 degree dive without exceeding 60 kph at idle, and WILL stall over the runway threshold if I hold idle at landing. I need about 3~3,5K RPM for landing.
Chances are, for your particular plane, the 17 x 8 is the better choice due to the wider speed envelope.
Last edited by 1967brutus; 09-09-2023 at 11:19 PM.
09-09-2023, 11:26 PM
#1856
IF.... IF you go to an 18 x 6, then at least make sure it's either a good woody (I particularly like the ones JustEngines supplies and have a bit of a dislike for for example MenzS), or better, the APC 18 x 6W... That is the one I run.
Mind you, it COULD be necessary to reduce servo-speed a touch on the upstroke of the throttle, due to the larger inertia of the prop: With gasoline, if the throttle opens TOO quick for the acceleration of the engine, mixture temporarily gets out of whack and that can lead to trouble. No biggie, do NOT adjust acceleration problems with the idle mixture, just reduce servo travelling speed to say, 0,5 ~ 0,7 sec, that usually does the trick.
The downside of an 18 x 6 prop is that at idle it functions as a huge airbrake, and you MUST come in on the throttle at landing. My BigLift (the plane in the vid I posted) can maintain a 45 degree dive without exceeding 60 kph at idle, and WILL stall over the runway threshold if I hold idle at landing. I need about 3~3,5K RPM for landing.
Mind you, it COULD be necessary to reduce servo-speed a touch on the upstroke of the throttle, due to the larger inertia of the prop: With gasoline, if the throttle opens TOO quick for the acceleration of the engine, mixture temporarily gets out of whack and that can lead to trouble. No biggie, do NOT adjust acceleration problems with the idle mixture, just reduce servo travelling speed to say, 0,5 ~ 0,7 sec, that usually does the trick.
The downside of an 18 x 6 prop is that at idle it functions as a huge airbrake, and you MUST come in on the throttle at landing. My BigLift (the plane in the vid I posted) can maintain a 45 degree dive without exceeding 60 kph at idle, and WILL stall over the runway threshold if I hold idle at landing. I need about 3~3,5K RPM for landing.
If i have to go buy a prop ,i will definitely get a decent wood prop, i have asked a club member for a prop and hopefully he remembers to take a look for one, also another member i know of has a master airscrew prop i will get a lone of that for a test,,
well here goes for the servo slow down! Imy transmitter only has manual function for servo slow down, my 👍 🤣
Call me a mad man! So i went back a level when i had a spektrum dx8 gen1 problem, and wanted to fly and grabbed a dx7s locally and was able to continue flying, but instead of buying replacement brand transmitter/recievers i brought another plane ,, lucky enough transmission has been stable but still a thought of swapping out spektrum altogether...
i miss having servo delay and throttle curve
09-10-2023, 12:57 AM
#1857
Senior Member
Thread Starter
If i have to go buy a prop ,i will definitely get a decent wood prop, i have asked a club member for a prop and hopefully he remembers to take a look for one, also another member i know of has a master airscrew prop i will get a lone of that for a test,,
well here goes for the servo slow down! Imy transmitter only has manual function for servo slow down, my 👍 🤣
Call me a mad man! So i went back a level when i had a spektrum dx8 gen1 problem, and wanted to fly and grabbed a dx7s locally and was able to continue flying, but instead of buying replacement brand transmitter/recievers i brought another plane ,, lucky enough transmission has been stable but still a thought of swapping out spektrum altogether...
i miss having servo delay and throttle curve
well here goes for the servo slow down! Imy transmitter only has manual function for servo slow down, my 👍 🤣
Call me a mad man! So i went back a level when i had a spektrum dx8 gen1 problem, and wanted to fly and grabbed a dx7s locally and was able to continue flying, but instead of buying replacement brand transmitter/recievers i brought another plane ,, lucky enough transmission has been stable but still a thought of swapping out spektrum altogether...
i miss having servo delay and throttle curve
As for transmitters; there is a learning curve to it, but you can't beat OpenTX for versatility.
Last edited by 1967brutus; 09-10-2023 at 12:59 AM.
09-10-2023, 01:25 AM
#1858
If your transmitter does not have a slowdown, chances are you can mainly solve the issie with an as asymetric as possible transmission from servo arm to carb: Set up your arms and links such, that at idle the pushrod angles as close to 90 degrees to the carburettor-lever, and at WOT as close as possible to 90 degrees with the servo arm. That will result in a very progressive linkage, which will "slow down" the movement of the carb throttle around idle. Replacing the throttle servo for a cheap generic "not fast" standard servo helps as well. Something like a Futaba S3010 comes to mind. It will take out the sharpest edges of the situation. You got that groove modified, means I am pretty sure you can get this covered as well
As for transmitters; there is a learning curve to it, but you can't beat OpenTX for versatility.
As for transmitters; there is a learning curve to it, but you can't beat OpenTX for versatility.
i think frsky is definitely the way to go , il have to get in on one , i need more features already anyway, apart from having no servo slowdown the engine responds really well to a sudden throttle change even though it would make a smoother transition with slowdown..
Oh and a member took interest wondering if he could modify his os 55ax, i said yes, but of course some smart guy heard in and come up to say.. surely youd only do that for a diy project, it wouldnt servo ay gainful purpose, well i simply and quickly advised him of 2 unbeatable gains to achieve, he turned away
09-10-2023, 01:34 AM
#1859
OpenTX and Edgetx are going the way of the Dodo bird it seems. Neither OS supports the new Archer Plus receivers and there seems to be little interest by developers to make that happen. It's all about the newer Ethos and erskyTx operating systems now.
09-10-2023, 01:54 AM
#1861
Senior Member
Thread Starter
I get what you mean with the servo/throttle arms ,, il check and alter that accordingly, as for a older servos like that, would it be advisable to run it with 6v reciever pac? Im using hitec hs422,s in the plane..
i think frsky is definitely the way to go , il have to get in on one , i need more features already anyway, apart from having no servo slowdown the engine responds really well to a sudden throttle change even though it would make a smoother transition with slowdown..
Oh and a member took interest wondering if he could modify his os 55ax, i said yes, but of course some smart guy heard in and come up to say.. surely youd only do that for a diy project, it wouldnt servo ay gainful purpose, well i simply and quickly advised him of 2 unbeatable gains to achieve, he turned away
i think frsky is definitely the way to go , il have to get in on one , i need more features already anyway, apart from having no servo slowdown the engine responds really well to a sudden throttle change even though it would make a smoother transition with slowdown..
Oh and a member took interest wondering if he could modify his os 55ax, i said yes, but of course some smart guy heard in and come up to say.. surely youd only do that for a diy project, it wouldnt servo ay gainful purpose, well i simply and quickly advised him of 2 unbeatable gains to achieve, he turned away
On the AX, oh yes, it is very doable, and it damn sure serves gainful purposes: Fuel consumption for one thing, unlimited fuel availlability for another, elimination of rusty bearings for a third, a rocksolid and consistent "first flip start" for a fourth, the obsolence of a LOT of field equipment (starter, glow driver, tools, spare plugs, and a strong reduction of after-flight cleaning paraphernalia) for a fifth.
I used to carry around a fieldbox of 15 kilo, (for comparison: in dimensions about the size of max allowed cabin luggage on most airliners) that contained heavy batteries, starters, tools, 5 litres of glow fuel, cleaning liquids, rags etc etc.
Nowadays I bring a tiny fuel can (1 litre suffices for even events and demo-days), and a tiny toolkit the size of a kids shoe-box, and a single pack of wet-wipes that last me about a year.
If pressed for time, I bring this plane:
Last edited by 1967brutus; 09-10-2023 at 03:08 AM.
09-10-2023, 02:13 AM
#1862
My first gasoline converted plane was flown with a stone-age Futaba FC-18, which also did not have a servo slowdown. They used to be commercially availlable, but I had one made by the same guy that makes my solenoid controllers.
On the AX, oh yes, it is very doable, and it damn sure serves gainful purposes: Fuel consumption for one thing, unlimited fuel availlability for another, elimination of rusty bearings for a third, a rocksolid and consistent "first flip start" for a fourth, the obsolence of a LOT of field equipment (starter, glow driver, tools, spare plugs, and a strong reduction of after-flight cleaning paraphernalia) for a fifth.
It has a 6 oz/180 ml tank and gives me 6 flights of 10 minutes without refuelling. Except for the wing, everything you see in the vid, is what I need for a moderate afternoon at the club.
On the AX, oh yes, it is very doable, and it damn sure serves gainful purposes: Fuel consumption for one thing, unlimited fuel availlability for another, elimination of rusty bearings for a third, a rocksolid and consistent "first flip start" for a fourth, the obsolence of a LOT of field equipment (starter, glow driver, tools, spare plugs, and a strong reduction of after-flight cleaning paraphernalia) for a fifth.
It has a 6 oz/180 ml tank and gives me 6 flights of 10 minutes without refuelling. Except for the wing, everything you see in the vid, is what I need for a moderate afternoon at the club.
my 20cc radial does 20mins on a 200ml with enough to land,
20my edition to the field box is 1lt fuel a rag a couple of tools and a cordless socket gun for instant starts ,, first hit with the starter its away, (like a car)
09-10-2023, 03:41 AM
#1863
Senior Member
Thread Starter
Spark ignition #6 minimal failure compared to flamecouts of glow plugs, and so on..but also a quick ignition system is a os g5 glow plug,
my 20cc radial does 20mins on a 200ml with enough to land,
20my edition to the field box is 1lt fuel a rag a couple of tools and a cordless socket gun for instant starts ,, first hit with the starter its away, (like a car)
my 20cc radial does 20mins on a 200ml with enough to land,
20my edition to the field box is 1lt fuel a rag a couple of tools and a cordless socket gun for instant starts ,, first hit with the starter its away, (like a car)
Your boxer should get similar fuel economy compared to your radial. Mine does about 45 minutes of normal flying on 250 ml, or about 8 safe towing flights (each consisting of roughly 1 minute of WOT on the way up, descent, low pass for line drop and a go-around for landing).
As a global rule of thumb, you can check the engine power with a propcalculator, then assume approx 300 grammes per kWh, or roughly 300 ml per hour per horsepower delivered. My Boxer clocked at 2,5 hp once, absolute peak I ever observed, therefore it should roughly consume approx 0,75 litres per hour at WOT, give or take. Never measured that to any degree of accuracy, but it seems consistent looking at the towing flights: I typically get 8 safe tows from a tank with about 20% reserve, so a consumption of approx 200 ml. The 8 climb-outs of 1 minute allready are responsible for half of that volume. Take in account the warm-up runs on the ground (cold engine takes 45~60 seconds to reach the temperatures where I am willing to give it WOT), the taxiing, the descent and go-arounds, and I'd say that is not too far off.
I have an Align selfcontained starter for those planes that have a difficult to reach carb (making a proper prime virtually impossible).
09-10-2023, 09:40 AM
#1866
alright, i'm back at coding and my plan is to add chris' air pump controller to my solenoid controller for a unified controller that takes less space than the two separate controllers. the hope is to add the following functionality:
RPM telemetry back to the transmitter (because, why not since we'll have that data)
prime the engine from the transmitter (chris already has this)
use a single transmitter channel for both mixture control and for priming (why not use a 2000uS pulse to initiate priming, after all, we would never need a 2000 uS pulse for the solenoid channel anyway and the solenoid should be fully opened during priming procedures anyway.)i have a few questions for you chris. i haven't connected one of my ignitions to one of my oscilloscopes. i believe your design uses an optocoupler for the RPM signal from the ignition to the controller, and i believe you're using a 5v arduino pro mini (maybe not). the seeeduino xiao will only allow 3.3v max into a pin before letting the magic smoke out so i was planning on using a simple 2 resistor voltage divider to scale the RPM signal to less than 3v, and likely closer to 2 or 2.5v for a bit of safety since 1.8v or above is considered a logic high input. did you take any measurements of the RPM signal and if so, what voltage can i expect on that wire from the CDI?
your code has 255-40 = 215 distinct steps for the air pump output. have you found that to be sufficient or should i attempt to get a higher resolution from the pin controlling the air pump like i did with the solenoid control pin on my controller?
i seem to recall you were using a needle valve bleeded to allow the tank pressure to drop when the pump slows down. did you just guess at the setting or did you measure the pressures attained with muffler pressure and try to duplicate that with the pump?
does this setup eliminate the need for a crap trap all together or did you still require something to keep fuel from backing up into the air pump? it's been a while and my memory is no longer fresh.
you've been using this method for a while now. if you were to make any other changes to your setup, what would they be, because now's the time to implement new functionality while i'm at it.
RPM telemetry back to the transmitter (because, why not since we'll have that data)
prime the engine from the transmitter (chris already has this)
use a single transmitter channel for both mixture control and for priming (why not use a 2000uS pulse to initiate priming, after all, we would never need a 2000 uS pulse for the solenoid channel anyway and the solenoid should be fully opened during priming procedures anyway.)
your code has 255-40 = 215 distinct steps for the air pump output. have you found that to be sufficient or should i attempt to get a higher resolution from the pin controlling the air pump like i did with the solenoid control pin on my controller?
i seem to recall you were using a needle valve bleeded to allow the tank pressure to drop when the pump slows down. did you just guess at the setting or did you measure the pressures attained with muffler pressure and try to duplicate that with the pump?
does this setup eliminate the need for a crap trap all together or did you still require something to keep fuel from backing up into the air pump? it's been a while and my memory is no longer fresh.
you've been using this method for a while now. if you were to make any other changes to your setup, what would they be, because now's the time to implement new functionality while i'm at it.
09-10-2023, 10:26 AM
#1868
Senior Member
Thread Starter
alright, i'm back at coding and my plan is to add chris' air pump controller to my solenoid controller for a unified controller that takes less space than the two separate controllers. the hope is to add the following functionality:
RPM telemetry back to the transmitter (because, why not since we'll have that data)
prime the engine from the transmitter (chris already has this)
use a single transmitter channel for both mixture control and for priming (why not use a 2000uS pulse to initiate priming, after all, we would never need a 2000 uS pulse for the solenoid channel anyway and the solenoid should be fully opened during priming procedures anyway.)i have a few questions for you chris. i haven't connected one of my ignitions to one of my oscilloscopes. i believe your design uses an optocoupler for the RPM signal from the ignition to the controller, and i believe you're using a 5v arduino pro mini (maybe not). the seeeduino xiao will only allow 3.3v max into a pin before letting the magic smoke out so i was planning on using a simple 2 resistor voltage divider to scale the RPM signal to less than 3v, and likely closer to 2 or 2.5v for a bit of safety since 1.8v or above is considered a logic high input. did you take any measurements of the RPM signal and if so, what voltage can i expect on that wire from the CDI?
your code has 255-40 = 215 distinct steps for the air pump output. have you found that to be sufficient or should i attempt to get a higher resolution from the pin controlling the air pump like i did with the solenoid control pin on my controller?
i seem to recall you were using a needle valve bleeded to allow the tank pressure to drop when the pump slows down. did you just guess at the setting or did you measure the pressures attained with muffler pressure and try to duplicate that with the pump?
does this setup eliminate the need for a crap trap all together or did you still require something to keep fuel from backing up into the air pump? it's been a while and my memory is no longer fresh.
you've been using this method for a while now. if you were to make any other changes to your setup, what would they be, because now's the time to implement new functionality while i'm at it.
RPM telemetry back to the transmitter (because, why not since we'll have that data)
prime the engine from the transmitter (chris already has this)
use a single transmitter channel for both mixture control and for priming (why not use a 2000uS pulse to initiate priming, after all, we would never need a 2000 uS pulse for the solenoid channel anyway and the solenoid should be fully opened during priming procedures anyway.)
your code has 255-40 = 215 distinct steps for the air pump output. have you found that to be sufficient or should i attempt to get a higher resolution from the pin controlling the air pump like i did with the solenoid control pin on my controller?
i seem to recall you were using a needle valve bleeded to allow the tank pressure to drop when the pump slows down. did you just guess at the setting or did you measure the pressures attained with muffler pressure and try to duplicate that with the pump?
does this setup eliminate the need for a crap trap all together or did you still require something to keep fuel from backing up into the air pump? it's been a while and my memory is no longer fresh.
you've been using this method for a while now. if you were to make any other changes to your setup, what would they be, because now's the time to implement new functionality while i'm at it.
09-10-2023, 11:31 AM
#1870
09-10-2023, 01:33 PM
#1871
09-10-2023, 09:23 PM
#1872
Senior Member
Thread Starter
Keep in mind that I am slightly autistic WRT numbers, so I measure...Maybe not with the accuracy of a swiss clock, but still...
I am guessing your engine consumes about 200 ml with 15 minutes of your flying style, mine does that with 8 consecutive tows, which all things considered is not that different from your typical "15 minutes of flight". I would not worry about it, because I can assure you, these engines are fairly consistent WRT fuel consumption, and would it really be guzzling, you would allready have complained about the humongous amounts of crud on the plane...
09-10-2023, 09:37 PM
#1873
Not really... All things considered (your flights have a LOT more "WOT" than mine, so far you have been running fairly high RPM, and "a few mins back-up" is difficult to quantify) I don't think your Boxer is particularly thirsty.
Keep in mind that I am slightly autistic WRT numbers, so I measure...Maybe not with the accuracy of a swiss clock, but still...
I am guessing your engine consumes about 200 ml with 15 minutes of your flying style, mine does that with 8 consecutive tows, which all things considered is not that different from your typical "15 minutes of flight". I would not worry about it, because I can assure you, these engines are fairly consistent WRT fuel consumption, and would it really be guzzling, you would allready have complained about the humongous amounts of crud on the plane...
Keep in mind that I am slightly autistic WRT numbers, so I measure...Maybe not with the accuracy of a swiss clock, but still...
I am guessing your engine consumes about 200 ml with 15 minutes of your flying style, mine does that with 8 consecutive tows, which all things considered is not that different from your typical "15 minutes of flight". I would not worry about it, because I can assure you, these engines are fairly consistent WRT fuel consumption, and would it really be guzzling, you would allready have complained about the humongous amounts of crud on the plane...
09-11-2023, 07:10 PM
#1874
Well another great day with the boxer, except had to lean the mixture a fair bit today, slightly weird..
i had another member to meet at the club he liked the boxer till i told him its converted, he looked at me with worry and told me his story of a purchase, he brought a os ft300 of a guy that sent the engine from Australia to mmm and then i guess sold it on to this guy cause it didn't run well, this guy tells me of his pain trying to get it running properly with little luck,well after conrods overheating he purchased new ones then still had more heating problems and now sits on a bench..he tells me glow engines cant run on gasoline because it causes too much heat, i simply replied that carburettor is the big problem, told him to see how long mine lasts , that guy had no idea what he was doing, but insisted that gasoline is to blame in total..
i had another member to meet at the club he liked the boxer till i told him its converted, he looked at me with worry and told me his story of a purchase, he brought a os ft300 of a guy that sent the engine from Australia to mmm and then i guess sold it on to this guy cause it didn't run well, this guy tells me of his pain trying to get it running properly with little luck,well after conrods overheating he purchased new ones then still had more heating problems and now sits on a bench..he tells me glow engines cant run on gasoline because it causes too much heat, i simply replied that carburettor is the big problem, told him to see how long mine lasts , that guy had no idea what he was doing, but insisted that gasoline is to blame in total..
09-11-2023, 08:33 PM
#1875
Senior Member
Thread Starter
You are AFAIK still running on the needles only, and then needle tweaks are inevitable with changes in climate. The latest versions of the solenoid systems largely compensate for that.
i had another member to meet at the club he liked the boxer till i told him its converted, he looked at me with worry and told me his story of a purchase, he brought a os ft300 of a guy that sent the engine from Australia to mmm and then i guess sold it on to this guy cause it didn't run well, this guy tells me of his pain trying to get it running properly with little luck,well after conrods overheating he purchased new ones then still had more heating problems and now sits on a bench..he tells me glow engines cant run on gasoline because it causes too much heat, i simply replied that carburettor is the big problem, told him to see how long mine lasts , that guy had no idea what he was doing, but insisted that gasoline is to blame in total..
I know the ASP at the very least, survives a 20:1 ratio fairly well, in fact runs excellent on 15:1, but I prefer 10:1 myself, just because I have a fairly wide range of engine sizes converted (among them an OS Wankel that I absolutely do not want to risk) and I don't want to carry around different mixes.
Last edited by 1967brutus; 09-11-2023 at 08:50 PM.
