Mounting a 4 stroke inverted
10-08-2009, 10:50 AM
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Mounting a 4 stroke inverted
Hi all,
I am considering mounting my Os72 four stroke inverted in my Great Planes J3 Cub. Besides requiring a glow driver are there any other issues that I should be aware of?
Ed
I am considering mounting my Os72 four stroke inverted in my Great Planes J3 Cub. Besides requiring a glow driver are there any other issues that I should be aware of?
Ed
10-08-2009, 11:41 AM
#2
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RE: Mounting a 4 stroke inverted
If you have the engine set up properly you won't
need a glo driver. Just make sure the tank is correctly
positioned.
Regards,
Roby
need a glo driver. Just make sure the tank is correctly
positioned.
Regards,
Roby
10-08-2009, 11:47 AM
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RE: Mounting a 4 stroke inverted
Ed:
1) There are those that maintain you don't need a glow driver. Personally I think it's a good idea, if nothing else it makes the engine easier to start when it's inverted. If you do run an on-board glow, use a separate battery from your receiver pack to power it. I'm told there's a possibility of feedback from the glow driver getting back to the receiver. This might be one of the infamous hobby "myths", but why take the chance?
2) You'll probably end up leaning out the engine a bit more than if it were mounted upright.
3) Optimally, the centerline of your fuel tank should line up with the center of the carb. I'd doubt that 1/4" either way would make a difference, but if the tanks appreciably higher than the carb, you could end up with fuel siphoning down into the carb, which can cause the engine to flood. That's the biggest reason I like the on-board glow: it gives me confidence that the glow plug stays lit at low engine speeds, which lessens the chance of a dead-stick.
Fred
1) There are those that maintain you don't need a glow driver. Personally I think it's a good idea, if nothing else it makes the engine easier to start when it's inverted. If you do run an on-board glow, use a separate battery from your receiver pack to power it. I'm told there's a possibility of feedback from the glow driver getting back to the receiver. This might be one of the infamous hobby "myths", but why take the chance?
2) You'll probably end up leaning out the engine a bit more than if it were mounted upright.
3) Optimally, the centerline of your fuel tank should line up with the center of the carb. I'd doubt that 1/4" either way would make a difference, but if the tanks appreciably higher than the carb, you could end up with fuel siphoning down into the carb, which can cause the engine to flood. That's the biggest reason I like the on-board glow: it gives me confidence that the glow plug stays lit at low engine speeds, which lessens the chance of a dead-stick.
Fred
10-08-2009, 01:16 PM
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RE: Mounting a 4 stroke inverted
Fred,
I agree with you. I would rather opt for the on board glow driver which gives you a better burn in the cylinder. Nelson Hobbies sells what they call an "intellegent glow driver" It does not turn on the glow plug at a preset throttle position. Rather it continually measures the resistance of the glow plug and turns it on only when the glow plug cools below a preset resistance. More information on this can be found at:
http://www.nelsonhobby.com/
Thnaks for your comments
I agree with you. I would rather opt for the on board glow driver which gives you a better burn in the cylinder. Nelson Hobbies sells what they call an "intellegent glow driver" It does not turn on the glow plug at a preset throttle position. Rather it continually measures the resistance of the glow plug and turns it on only when the glow plug cools below a preset resistance. More information on this can be found at:
http://www.nelsonhobby.com/
Thnaks for your comments
10-08-2009, 05:12 PM
#5
My Feedback: (7)
RE: Mounting a 4 stroke inverted
I have run inverted 4 strokes for years without on board glow. I have several of the Nelson Hobby glow drivers, never had a problem with them. I use them on models that I just can't bring myself to cut access holes in the cowls.
10-08-2009, 05:23 PM
#6
RE: Mounting a 4 stroke inverted
I would rather opt for the on board glow driver which gives you a better burn in the cylinder.
the above statement is incorrect.It is the catalytic action between the alcohol in the fuel and platinum in the glow plug that causes the burn.we use a battery to warm things up and help the catalytic action.there have been times when glow engines have started with no battery connected.
the above statement is incorrect.It is the catalytic action between the alcohol in the fuel and platinum in the glow plug that causes the burn.we use a battery to warm things up and help the catalytic action.there have been times when glow engines have started with no battery connected.
10-09-2009, 12:37 AM
#7
RE: Mounting a 4 stroke inverted
I had my OS .70 mounted inverted without any onboard glow... I did have a remote-glow hook-up(Dubro) so I didn't have to fiddle with the igniter on an inverted engine... and it was all nicely tucked underneath.. with only the recepticle on the side of the plane.. and even that has a cool little swinging cover.
My experience was that it was extremely important to take alot of time to dial that engine/mixture in to a very precise tuning. It took an afternoon or so, but once the low-end mixture was set, it was usually just a click or 2 of the main needle that kept it running well... they are great engines... and as I said can be precisely tuned for alot of different conditions.
I also have a memory of a Cub in about that size range that the builder did side mount the engine.. and then made a dummy out of wood for the other side.... when he was done the dummy very closely resemembled the live engine.. and he had what looked be an authentic front engine area on his Cub.
My experience was that it was extremely important to take alot of time to dial that engine/mixture in to a very precise tuning. It took an afternoon or so, but once the low-end mixture was set, it was usually just a click or 2 of the main needle that kept it running well... they are great engines... and as I said can be precisely tuned for alot of different conditions.
I also have a memory of a Cub in about that size range that the builder did side mount the engine.. and then made a dummy out of wood for the other side.... when he was done the dummy very closely resemembled the live engine.. and he had what looked be an authentic front engine area on his Cub.
10-10-2009, 06:39 AM
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RE: Mounting a 4 stroke inverted
Hi Bigtim,
I have never ran an engine inverted myself. If its a matter of good tuning, I may try without it first to see how it works.
Ed
I have never ran an engine inverted myself. If its a matter of good tuning, I may try without it first to see how it works.
Ed
10-10-2009, 07:25 AM
#10
RE: Mounting a 4 stroke inverted
ORIGINAL: sleded42
Hi all,
I am considering mounting my Os72 four stroke inverted in my Great Planes J3 Cub. Besides requiring a glow driver are there any other issues that I should be aware of?
Ed
Hi all,
I am considering mounting my Os72 four stroke inverted in my Great Planes J3 Cub. Besides requiring a glow driver are there any other issues that I should be aware of?
Ed
An on-board glow driver is not required. If you use one and it fails at the field, you have a problem getting to the glow plug with a regular glow heater. I speak from experience.
The prime consideration is tank position. The inverted engine's carburetor centerline will be much lower than the upright or side-mounted engine. Make sure the centerline of the tank can be placed at the same level as your carburetor centerline. If the inverted engine's carburetor will be at the level of the bottom of the tank, you need to lower the tank or mount the engine sideways.
Just my opinion, don't use an on-board glow driver.
Dave Olson
10-11-2009, 09:45 PM
#12
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RE: Mounting a 4 stroke inverted
OS 1.20 inverted. If the tank is mounted correctly no problem. All the engines I have run inverted ran just a taste on the lean side on the low end. Just for grins I spent several hours installing a nice on board glow driver I have had for years and never used. The reason was just to make it easier to start the engine without using a glow stick and just a bit of piece of mind. After hours of fooling around with the driver it didn't work?? Plenty of voltage but no glow!! I pulled the system and will just take the time to set the needles correctly. Guess the driver sat under the bench too long??
Gene
Gene
10-13-2009, 03:58 AM
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RE: Mounting a 4 stroke inverted
No issues at all, 4 strokes run fine inverted.
Make sure the tank height is correct, just like with upright.
Make sure needles are set correctly, just like with upright.
No more need for on board glow than upright.
And they will run just as well as they do when upright.
I find starting easier because gravity makes sure the prime goes right into the head, but be carefull, it is easier to overprime and hydraulic lock the engine. If you do lock it, it's easier to fix. Just turn the engine backwards and the prime runs out the exhaust.
Actually here in the Southern hemisphere all engines work better inverted. Thats because the pistons are designed to go up and down when in the Northern hemisphere, so we either have to change the pistons for ones that go down and up, or run the engine inverted. Actually come to think of it your inverted engine would go better with a Southern hemisphere 'down and up' piston in it, I could sell you one if you like. They are a little bit more expensive (obviousely) but well worth it, let me know.
Dave H
Make sure the tank height is correct, just like with upright.
Make sure needles are set correctly, just like with upright.
No more need for on board glow than upright.
And they will run just as well as they do when upright.
I find starting easier because gravity makes sure the prime goes right into the head, but be carefull, it is easier to overprime and hydraulic lock the engine. If you do lock it, it's easier to fix. Just turn the engine backwards and the prime runs out the exhaust.
Actually here in the Southern hemisphere all engines work better inverted. Thats because the pistons are designed to go up and down when in the Northern hemisphere, so we either have to change the pistons for ones that go down and up, or run the engine inverted. Actually come to think of it your inverted engine would go better with a Southern hemisphere 'down and up' piston in it, I could sell you one if you like. They are a little bit more expensive (obviousely) but well worth it, let me know.
Dave H
10-13-2009, 01:22 PM
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RE: Mounting a 4 stroke inverted
ORIGINAL: gerryndennis
No issues at all, 4 strokes run fine inverted.
Make sure the tank height is correct, just like with upright.
Make sure needles are set correctly, just like with upright.
No more need for on board glow than upright.
And they will run just as well as they do when upright.
I find starting easier because gravity makes sure the prime goes right into the head, but be carefull, it is easier to overprime and hydraulic lock the engine. If you do lock it, it's easier to fix. Just turn the engine backwards and the prime runs out the exhaust.
Actually here in the Southern hemisphere all engines work better inverted. Thats because the pistons are designed to go up and down when in the Northern hemisphere, so we either have to change the pistons for ones that go down and up, or run the engine inverted. Actually come to think of it your inverted engine would go better with a Southern hemisphere 'down and up' piston in it, I could sell you one if you like. They are a little bit more expensive (obviousely) but well worth it, let me know.
Dave H
No issues at all, 4 strokes run fine inverted.
Make sure the tank height is correct, just like with upright.
Make sure needles are set correctly, just like with upright.
No more need for on board glow than upright.
And they will run just as well as they do when upright.
I find starting easier because gravity makes sure the prime goes right into the head, but be carefull, it is easier to overprime and hydraulic lock the engine. If you do lock it, it's easier to fix. Just turn the engine backwards and the prime runs out the exhaust.
Actually here in the Southern hemisphere all engines work better inverted. Thats because the pistons are designed to go up and down when in the Northern hemisphere, so we either have to change the pistons for ones that go down and up, or run the engine inverted. Actually come to think of it your inverted engine would go better with a Southern hemisphere 'down and up' piston in it, I could sell you one if you like. They are a little bit more expensive (obviousely) but well worth it, let me know.
Dave H
10-13-2009, 09:40 PM
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RE: Mounting a 4 stroke inverted
Hi Augie11
No not at all, Coriolis is why we all have to use reverse pitch propellers down here, but has nothing to do with pistons having to go down and up instead of up and down. It's an easy mistake to make.
Can I sell you any Southern hemisphere pistons? They are really good.
Dave H
I think it must be the Coriolus effect ; )
Can I sell you any Southern hemisphere pistons? They are really good.Dave H
