Heli's flying diesel?
#26
Thread Starter
RE: Heli's flying diesel?
Oh, and don't forget the head gasket, it goes back on too. You see it on top of the engine. And you can see all the black dust from burning the clutch liner out when I hit the tree.... I was just stunned and forgot to kill the governor and engine for like 30 seconds..... Duh
#28
Thread Starter
RE: Heli's flying diesel?
Mr. Davis had told me in a phone conversation I didn't have to use the tuned pipe, so I dug up one of the stock 50 mufflers and am going to use that.
Money saved there....
Money saved there....
#30
Thread Starter
RE: Heli's flying diesel?
Plenty of room to get to the head and adjust the compression hex nut if needed. I may even have to close off some of the front next to the head to keep the heat up. The diesel is supposed to run much cooler and you have to let em' warm up for a minute or so for them to smooth out.
#31
Thread Starter
RE: Heli's flying diesel?
Here is a finished look at the engine mount from the side etc... You can't tell and difference.
I like the fact that there is no remote glow needed, even though the voltage regulators I use has a remote glow built into them.
I like the fact that there is no remote glow needed, even though the voltage regulators I use has a remote glow built into them.
#32
Thread Starter
RE: Heli's flying diesel?
As far as gear ratio's, I went down on the main shaft gear from a 96 tooth to a 85 tooth. Still a 11 tooth pinion on the clutch housing, I would like to have a 12, 13 and 14 tooth to experiment with. That would be like adding a bigger prop because of the more torque the diesel is supposed to produce.
I ordered the bulb for fueling, it sucks for my tank, way to small, takes like 5 bulbs to not hardly fill the tank. I need a gas hand crank pump and a tin can.... Next thing on my list to get.
I removed the main blades, and tail blades for tinkering, didn't want the thing trying to fly or spin on the ground.
I put a little less than half tank in the heli, went outside and started trying to get it to run. The instruction that came with the head said to just start with your nitro settings and that would be a very rich setting to start with.
After a couple minutes of playing with the compression hex screw, it sprang to life, fast run, then slow run, then fast etc... I kept messing with the compession hex screw until it smoothed out.... Should have left it alone, the engine just needed to heat up. Duh...my first diesel.
After it smoothed out, I would advance the throttle and it would like bluh bluh, so I leaned the high screw, about 6 clicks, helped somewhat, kept leaning the high end until it would take gas good.
Killed the throttle with the trim tab. Tried to restart, and had to increase the compression hex again. This time, the engine was warm and it was smooth, I I left it there. All seems to be ok so far, it seems a bit slower to spool up that nitro, I don't know for sure, maybe just the nature of the beast, but with the increased torque and govenror I don't care as long as it holds 2k on the head speed.
Well the clouds rolled in and rain started, so this days experimentation is over. I will say the fuel has a lot of oil in it and I forgot to add a exhaust deflector on the new muffler, so I really greased up the tail shaft.
More will follow in the next few days as i get time to take it to the field for some test flights. For now, I have to figure out something about the clunk, and maybe add back the header tank with a larger clunck or thinner fuel line. Off to the chainsaw shop and see what gas lines they have.
I ordered the bulb for fueling, it sucks for my tank, way to small, takes like 5 bulbs to not hardly fill the tank. I need a gas hand crank pump and a tin can.... Next thing on my list to get.
I removed the main blades, and tail blades for tinkering, didn't want the thing trying to fly or spin on the ground.
I put a little less than half tank in the heli, went outside and started trying to get it to run. The instruction that came with the head said to just start with your nitro settings and that would be a very rich setting to start with.
After a couple minutes of playing with the compression hex screw, it sprang to life, fast run, then slow run, then fast etc... I kept messing with the compession hex screw until it smoothed out.... Should have left it alone, the engine just needed to heat up. Duh...my first diesel.
After it smoothed out, I would advance the throttle and it would like bluh bluh, so I leaned the high screw, about 6 clicks, helped somewhat, kept leaning the high end until it would take gas good.
Killed the throttle with the trim tab. Tried to restart, and had to increase the compression hex again. This time, the engine was warm and it was smooth, I I left it there. All seems to be ok so far, it seems a bit slower to spool up that nitro, I don't know for sure, maybe just the nature of the beast, but with the increased torque and govenror I don't care as long as it holds 2k on the head speed.
Well the clouds rolled in and rain started, so this days experimentation is over. I will say the fuel has a lot of oil in it and I forgot to add a exhaust deflector on the new muffler, so I really greased up the tail shaft.
More will follow in the next few days as i get time to take it to the field for some test flights. For now, I have to figure out something about the clunk, and maybe add back the header tank with a larger clunck or thinner fuel line. Off to the chainsaw shop and see what gas lines they have.
#34
RE: Heli's flying diesel?
It is looking great. Do keep us informed as to how it does.
One thought is the Tygon tubing, New tubing tends to be more stiff, but after it has soaked in the fuel for a while it gets more soft and more flexible. I have taken to using some extra small Zip Ties to help clamp the tubing onto the brass tubing and the clunk so that it doesn't slip off. So I think you will find the Tygon tubing to be perfectly fine after it has soaked in the fuel for a while and become more flexible,
One thought is the Tygon tubing, New tubing tends to be more stiff, but after it has soaked in the fuel for a while it gets more soft and more flexible. I have taken to using some extra small Zip Ties to help clamp the tubing onto the brass tubing and the clunk so that it doesn't slip off. So I think you will find the Tygon tubing to be perfectly fine after it has soaked in the fuel for a while and become more flexible,
#35
Thread Starter
RE: Heli's flying diesel?
Thanks guys.
I'm still worried about the clunk, I hope the hose does get more limber and zip ties on the thing would be safer and add a small amount of weight.
I'm still worried about the clunk, I hope the hose does get more limber and zip ties on the thing would be safer and add a small amount of weight.
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RE: Heli's flying diesel?
Home Depot sells little packages of MTD fuel line in the lawn mower section. Each package contains 2 feet of small diameter blue line and 2 feet (or 1 foot cannot remember) of larger diameter yellow/green line. The blue line is too small to do anything with, but the green/yellow line fits the brass tubing very well and is very flexible. No need for zip-ties or extra weight on the clunk. I have been using it as the clunk line for my OS .40 diesel. No problems during inverted flight and I am only using a 4 oz tank. The DDD brand fuel line also fits the brass tubing well and is very soft/flexible.
#38
Thread Starter
RE: Heli's flying diesel?
Well I flew it today, it was in the mid 80's hot. The diesel fired right up, white smoke rolling from the muffler, a duh duh varoom duh duh for about a minute then it warmed up and kinda smoothed out. I set the throttle to only 80% max at recommended. I was taking the throttle kinda slow so a few clicks to richen it up and it took the throttle good. It would jump up and down with a little more authority than 20% nitro heli mix.
I flew around for about 10 minutes and landed with still over a half tank.
The head was around 122 and around the carb was 145 degrees, to hot, it would burn you. So I richened up the lower side about 4 degrees and let it cool for 10 minutes or so. Fired up and had to give it a click or two on the high side to take throttle again.
This time I hit switch mode 1, the govenror kicked up the head speed to 1850 rpm, it looped and rolled very nice, inverted had good power.
More smoke than I'm used to flew about 10 minutes, landed and back of engine was still getting to hot.
Richened up the low side another couple degrees, now I"m back at where it was for nitro.
Fired back up and about 30 seconds of warm up and I took off, hit switch mode 2, govenror is set at 2000 rpm's and very high rates.
Plenty of power, loop around itself, good inverted power, then it started to lean out a bit, I did a loop and didn't have the power at the bottom to pull out of the loop, or just barly did, still a semi crash. Nothing broken, just the two front landing screws pulled out of the plastic raptor frame. Went to next screw size up.
After inspection, the engine was indeed very hot and the pressure line on the stock muffler had melted off, I guess this was what caused the lean out.
I'm going to try a different type of gas line tomorrow and hope it wont melt.
What I have determined, I need a bigger pinion gear, now I'm running a 10t and a 85T I believe. A 12 tooth would probably be what this diesel likes because of the low end torque. It does get about 3 to 4 times the milage of nitro fuel, but the cost at 15 bucks a quart for Davis Diesel makes it not really worth switching unless you like to tinker and have the ability to brew your own. The castor is black\brown and quite oily but not that much more than Heli mix.
So if anyone can help me with the tuning, some suggestions for running the back of the engine cooler I would appriciate it.
And anyone have a good recipe for home brew diesel I would greatly appriciate it as well.
Kero, castor, Klotz KL-200 and ether are easy to find here so that would not be a problem.
I flew around for about 10 minutes and landed with still over a half tank.
The head was around 122 and around the carb was 145 degrees, to hot, it would burn you. So I richened up the lower side about 4 degrees and let it cool for 10 minutes or so. Fired up and had to give it a click or two on the high side to take throttle again.
This time I hit switch mode 1, the govenror kicked up the head speed to 1850 rpm, it looped and rolled very nice, inverted had good power.
More smoke than I'm used to flew about 10 minutes, landed and back of engine was still getting to hot.
Richened up the low side another couple degrees, now I"m back at where it was for nitro.
Fired back up and about 30 seconds of warm up and I took off, hit switch mode 2, govenror is set at 2000 rpm's and very high rates.
Plenty of power, loop around itself, good inverted power, then it started to lean out a bit, I did a loop and didn't have the power at the bottom to pull out of the loop, or just barly did, still a semi crash. Nothing broken, just the two front landing screws pulled out of the plastic raptor frame. Went to next screw size up.
After inspection, the engine was indeed very hot and the pressure line on the stock muffler had melted off, I guess this was what caused the lean out.
I'm going to try a different type of gas line tomorrow and hope it wont melt.
What I have determined, I need a bigger pinion gear, now I'm running a 10t and a 85T I believe. A 12 tooth would probably be what this diesel likes because of the low end torque. It does get about 3 to 4 times the milage of nitro fuel, but the cost at 15 bucks a quart for Davis Diesel makes it not really worth switching unless you like to tinker and have the ability to brew your own. The castor is black\brown and quite oily but not that much more than Heli mix.
So if anyone can help me with the tuning, some suggestions for running the back of the engine cooler I would appriciate it.
And anyone have a good recipe for home brew diesel I would greatly appriciate it as well.
Kero, castor, Klotz KL-200 and ether are easy to find here so that would not be a problem.
#39
Thread Starter
RE: Heli's flying diesel?
Could a fellow back off the ether some and get a cooler running engine?
What about running a mixture of Castor and synthetic ?
And in colder weather, would a short spray of ether in the carb help on cold starts? I worked my way through college on heavy equipment and in the winter we heated the plugs for a couple minutes then hit the starter and squirted ether in the breather to get our equipment to start.
What about running a mixture of Castor and synthetic ?
And in colder weather, would a short spray of ether in the carb help on cold starts? I worked my way through college on heavy equipment and in the winter we heated the plugs for a couple minutes then hit the starter and squirted ether in the breather to get our equipment to start.
#40
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RE: Heli's flying diesel?
ORIGINAL: bklambdin
Could a fellow back off the ether some and get a cooler running engine?
What about running a mixture of Castor and synthetic ?
And in colder weather, would a short spray of ether in the carb help on cold starts? I worked my way through college on heavy equipment and in the winter we heated the plugs for a couple minutes then hit the starter and squirted ether in the breather to get our equipment to start.
Could a fellow back off the ether some and get a cooler running engine?
What about running a mixture of Castor and synthetic ?
And in colder weather, would a short spray of ether in the carb help on cold starts? I worked my way through college on heavy equipment and in the winter we heated the plugs for a couple minutes then hit the starter and squirted ether in the breather to get our equipment to start.
20% oil, half castor/half synthetic would be a good place to start, although all synthetic is probably safe for a modern ABx motor.
30% Ether, solvent grade is fine if you can get it.
50% Kero, try and avoid the cheap stuff that produces a lot of soot when burnt, Jet-A1 should be ok.
Add 1 to 3% Ignition Improver. 1.5% would be a good place to start. Amsoil Cetane booster is 100% Diesel Ignition Improver and works great.
Just out of curiosity, what percentages were you using?
Ray
#41
Thread Starter
RE: Heli's flying diesel?
I just bought 2 quarts with the head from Davis Diesel.
I knew the price was high, but I wanted to try something store bought, to get a good base-line and then start blending from there until it ran the same.
Thanks
Brian
I knew the price was high, but I wanted to try something store bought, to get a good base-line and then start blending from there until it ran the same.
Thanks
Brian
#42
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RE: Heli's flying diesel?
ORIGINAL: bklambdin
Could a fellow back off the ether some and get a cooler running engine?
Could a fellow back off the ether some and get a cooler running engine?
Just wondering if you are bogging this engine down by using too high a gearing?
(This could be causing the heat issues in a cowled instalation.)
And after finding a reasonable run setting, has the contra piston protruded into the head?
#43
Thread Starter
RE: Heli's flying diesel?
No I still have a full turn and a half on the compression screw.
I just ordered a larger pinion gear for this engine trying to bog it down more, should have more torque, or that is what I thought. I'm running a 8.5 ratio now with the head speed set at 1850 rpm's, with a 12 tooth pinion and a 85 tooth main gear will put me to 7.08 ratio. If that don't help, I'll change the main to a 96 tooth and that will put me to 8.0 ratio.
I'm new to diesels, first one I've ever seen, and first one in our club. So there is still a learning curve.
I flew today with better results.
I increased the compression screw, drilled a hole in the stock muffler about half way back, pluged the hole with a bolt. This stopped the pressure hose from melting which caused the engine to lean out yesterday. I still have to let it run for a minute to warm up before it will take throttle, may need to go on up on the compression don't know, but with just those changes, I got the heat lower.
After flying in switch mode 1, head speed at 1850, for about 5 minutes, doing some hard flips and flops, inverted loops rolls etc...really putting a strain on the engine I landed and took some heat readings. Head 124, carb body 142, bottom engine plate 145, muffler at head connection 180 degrees.
I think this is still to hot, but not for sure, plenty of white smoke, but I don't know what to look for.
I could bog the engine down in some hard flip\flops but it could be the heat leaning out or it could be my throttle is set to only open to a max of 80% of wide open as Mr Davis said to do.
I really don't know what to do other than keep experminting and asking for ya'll help on the diesels.
Thanks
Brian
I just ordered a larger pinion gear for this engine trying to bog it down more, should have more torque, or that is what I thought. I'm running a 8.5 ratio now with the head speed set at 1850 rpm's, with a 12 tooth pinion and a 85 tooth main gear will put me to 7.08 ratio. If that don't help, I'll change the main to a 96 tooth and that will put me to 8.0 ratio.
I'm new to diesels, first one I've ever seen, and first one in our club. So there is still a learning curve.
I flew today with better results.
I increased the compression screw, drilled a hole in the stock muffler about half way back, pluged the hole with a bolt. This stopped the pressure hose from melting which caused the engine to lean out yesterday. I still have to let it run for a minute to warm up before it will take throttle, may need to go on up on the compression don't know, but with just those changes, I got the heat lower.
After flying in switch mode 1, head speed at 1850, for about 5 minutes, doing some hard flips and flops, inverted loops rolls etc...really putting a strain on the engine I landed and took some heat readings. Head 124, carb body 142, bottom engine plate 145, muffler at head connection 180 degrees.
I think this is still to hot, but not for sure, plenty of white smoke, but I don't know what to look for.
I could bog the engine down in some hard flip\flops but it could be the heat leaning out or it could be my throttle is set to only open to a max of 80% of wide open as Mr Davis said to do.
I really don't know what to do other than keep experminting and asking for ya'll help on the diesels.
Thanks
Brian
#44
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RE: Heli's flying diesel?
Brian,
Flew and sounded good at the field today. Pretty neat what you are doing. Definitely doesn't have the nice aroma of glow fuel though. If you get good results mixing the fuel I might be interested in deisel on one of my old Fox's. I've heard that Fox's make good diesel conversions. A 40 spinning a 12x6 prop sounds really nice for alot of 40 size sport planes. More like a 50ish 4 stroke.
Peace,
Jimmy
Flew and sounded good at the field today. Pretty neat what you are doing. Definitely doesn't have the nice aroma of glow fuel though. If you get good results mixing the fuel I might be interested in deisel on one of my old Fox's. I've heard that Fox's make good diesel conversions. A 40 spinning a 12x6 prop sounds really nice for alot of 40 size sport planes. More like a 50ish 4 stroke.
Peace,
Jimmy
#45
Thread Starter
RE: Heli's flying diesel?
Thanks Jimmy, you can go to Davis Diesel's site and they have a list of heads for the engines they do. If it's not listed you can call Mr.Davis and I bet he will have one that fits. My OS 50 Hyper was not listed there, but it's the same head as a 46 FX I think is what he said.
Brian
Brian
#46
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RE: Heli's flying diesel?
ORIGINAL: bklambdin
Thanks Jimmy, you can go to Davis Diesel's site and they have a list of heads for the engines they do. If it's not listed you can call Mr.Davis and I bet he will have one that fits. My OS 50 Hyper was not listed there, but it's the same head as a 46 FX I think is what he said.
Brian
Thanks Jimmy, you can go to Davis Diesel's site and they have a list of heads for the engines they do. If it's not listed you can call Mr.Davis and I bet he will have one that fits. My OS 50 Hyper was not listed there, but it's the same head as a 46 FX I think is what he said.
Brian
So perhaps you have the wrong head and indeed need one with a lot more fins on it to prevent overheating.
But then I have never flown a chopper before so what would I know?
#47
RE: Heli's flying diesel?
I think Davis doesn't machine fins into the diesel conversion heads anymore. The new heads are all finless from what I have seen. Older heads have fins on them. But some of the older RC helicopter engine diesel heads years ago did have more fins on them. I think getting the head more hot does a lot in aiding the compression ignition method of running the engines. One thing is that the fuel consumption with high performance diesel engines tends to approach that of glow engines. So one may or may not get a big improvement in fuel consumption.It depends on the engine of course.
yeah the Fox .45 works really well as a diesel. I put a new Fox carburetor on this old .45 when I did the diesel conversion on it.
It turns a 12x8 prop as good as if not better than my Saito .80 glow engine could. This engine has the older style diesel conversion head on it. As a matter of fact the .45 diesel turned the 12x8 prop as good as several other 10cc glow engines did.
yeah the Fox .45 works really well as a diesel. I put a new Fox carburetor on this old .45 when I did the diesel conversion on it.
It turns a 12x8 prop as good as if not better than my Saito .80 glow engine could. This engine has the older style diesel conversion head on it. As a matter of fact the .45 diesel turned the 12x8 prop as good as several other 10cc glow engines did.
#48
Thread Starter
RE: Heli's flying diesel?
ORIGINAL: Recycled Flyer
Something doesn't quite gel here, your head looks like a normal aero one (as you say, an OS FX46 head) and not a purpose built 'bee hive" replacement like that shown on the Davis homepage.
So perhaps you have the wrong head and indeed need one with a lot more fins on it to prevent overheating.
But then I have never flown a chopper before so what would I know?
ORIGINAL: bklambdin
Thanks Jimmy, you can go to Davis Diesel's site and they have a list of heads for the engines they do. If it's not listed you can call Mr.Davis and I bet he will have one that fits. My OS 50 Hyper was not listed there, but it's the same head as a 46 FX I think is what he said.
Brian
Thanks Jimmy, you can go to Davis Diesel's site and they have a list of heads for the engines they do. If it's not listed you can call Mr.Davis and I bet he will have one that fits. My OS 50 Hyper was not listed there, but it's the same head as a 46 FX I think is what he said.
Brian
So perhaps you have the wrong head and indeed need one with a lot more fins on it to prevent overheating.
But then I have never flown a chopper before so what would I know?
That is the new head. It has Mr.Davis's signature engraved on it and a serial number.
I just don't know how hot the diesels are supposed to run, we know nothing about them at all.
Brian
#49
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RE: Heli's flying diesel?
ORIGINAL: bklambdin
That is the new head.
That is the new head.
ORIGINAL: bklambdin
It has Mr.Davis's signature engraved on it and a serial number.
I just don't know how hot the diesels are supposed to run, we know nothing about them at all.
Brian
It has Mr.Davis's signature engraved on it and a serial number.
I just don't know how hot the diesels are supposed to run, we know nothing about them at all.
Brian
All Davis heads have fins on them, whether they are vertically milled or horizontally cut, it is the amount of them that is telling,
His signature diesel car engine from the DDD home page (pictured) sports a massive beehive 6 fin cooling head on it and the old glow head has seven,
Your head has only two fins,
All standard heli and car heads have these enlarged heat sinks on them to cope with the heat,
You have a non standard head and are claiming overheating issues (although the idle may benefit from it.)
So logically it seems that a two fin DDD head will suffer from overheating when only presented with the airflow from a 3" impeller that is centred on the lower crankcase.
Where to from here? Call Bob Davis I suppose and verify if the head you have is the head you need.
Good Luck.
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RE: Heli's flying diesel?
Hi Brian,
Congrats on your diesel helicopter success so far.
I've found that the 80% throttle recommendation on Davis conversions isn't always the case, some engines work fine with full throttle. Could be worth trying?
Most diesels run with the exhaust oil a light brown or honey colour, if the oil is black it can be a sign of running over compressed, although running too hot might do it as well. Then again some engines will run black when correctly adjusted.
That diesel mix that qazimoto recommends above is exactly the same as I use (1% DII for me). It runs and throttles superbly. The Davis ABC mix is 12% oil (I can look up the rest if you need it).
I tested a few props side by side on diesel and glow. My engine turned the smaller props faster on glow and the bigger props turned faster on diesel. But even though the big prop was better on diesel it still wasn't as much power as a medium size prop on either fuel. What I'm trying to say is you may get better results if you let your engine turn up a bit, even though it will handle a bigger pinion better on diesel than glow, you still may get better performance on the smaller pinion. Higher RPM should help the cooling too.
My experience is with diesels driving propellers, I have no experience of tuning diesel helicopters so please accept my apologies if this post is of no use to you but maybe my thoughts will be of some use.
I sounds like you are nearly there anyway, hope it goes well.
Dave H
Congrats on your diesel helicopter success so far.
I've found that the 80% throttle recommendation on Davis conversions isn't always the case, some engines work fine with full throttle. Could be worth trying?
Most diesels run with the exhaust oil a light brown or honey colour, if the oil is black it can be a sign of running over compressed, although running too hot might do it as well. Then again some engines will run black when correctly adjusted.
That diesel mix that qazimoto recommends above is exactly the same as I use (1% DII for me). It runs and throttles superbly. The Davis ABC mix is 12% oil (I can look up the rest if you need it).
I tested a few props side by side on diesel and glow. My engine turned the smaller props faster on glow and the bigger props turned faster on diesel. But even though the big prop was better on diesel it still wasn't as much power as a medium size prop on either fuel. What I'm trying to say is you may get better results if you let your engine turn up a bit, even though it will handle a bigger pinion better on diesel than glow, you still may get better performance on the smaller pinion. Higher RPM should help the cooling too.
My experience is with diesels driving propellers, I have no experience of tuning diesel helicopters so please accept my apologies if this post is of no use to you but maybe my thoughts will be of some use.
I sounds like you are nearly there anyway, hope it goes well.
Dave H