Problem caused by cowl ?
08-26-2008 | 09:48 AM
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From: Wieze, BELGIUM
Problem caused by cowl ?
Hello, i'm experiencing a strange phenomena when installing a YS 63S (that runs great in my other airplanes) in a new sukhoi (kyosho).
The engine runs fine on the ground with APC 13x6 on CP 20/20 at full throttle 10.750 rpm's (as in my other planes).
However when airborn the engine doesn't have it's usual punch when going full throttle.
Looked at all the usual suspects (fuel lines, tank pressure, glowplug etc..) but all are ok.
Could it be caused by the lack of airflow going through the cowl ? Mind you the engine isn't running hot at all, it's not lean at all, on the contrary it looks like it's going rich...
Any ideas ?
The engine runs fine on the ground with APC 13x6 on CP 20/20 at full throttle 10.750 rpm's (as in my other planes).
However when airborn the engine doesn't have it's usual punch when going full throttle.
Looked at all the usual suspects (fuel lines, tank pressure, glowplug etc..) but all are ok.
Could it be caused by the lack of airflow going through the cowl ? Mind you the engine isn't running hot at all, it's not lean at all, on the contrary it looks like it's going rich...
Any ideas ?
08-26-2008 | 11:46 AM
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From: Soddy Daisy, TN
RE: Problem caused by cowl ?
Sometimes you'll see an engine leaning out in flight because the air is rushing into the carb at an increased rate due to the speed of the plane compared to when it's just sitting on the ground. So, as a general rule, it's best to set the high end slightly rich to compensate for this phenonmenon. You might try richening the high end slightly and see if the performance improves.
But you said if anything you think the engine might be rich already, so the problem might have something to do with your prop selection. Even though the 13 x 6 has worked well on other models, you might want to try a different prop on the new plane. Different airframes react differently to motor/prop combinations, and you may find a different pitch or size on your prop will give you the perfomance you expect.
This is all assuming that the new Sukhoi isn't noticably heavier than the other planes you've had this engine mounted on. If it is, that, of course, will affect how much "punch" it has.
David
But you said if anything you think the engine might be rich already, so the problem might have something to do with your prop selection. Even though the 13 x 6 has worked well on other models, you might want to try a different prop on the new plane. Different airframes react differently to motor/prop combinations, and you may find a different pitch or size on your prop will give you the perfomance you expect.
This is all assuming that the new Sukhoi isn't noticably heavier than the other planes you've had this engine mounted on. If it is, that, of course, will affect how much "punch" it has.
David
08-26-2008 | 12:29 PM
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From: League City, TX
RE: Problem caused by cowl ?
ORIGINAL: dmccormick001
Sometimes you'll see an engine leaning out in flight because the air is rushing into the carb at an increased rate due to the speed of the plane compared to when it's just sitting on the ground. So, as a general rule, it's best to set the high end slightly rich to compensate for this phenonmenon. You might try richening the high end slightly and see if the performance improves.
But you said if anything you think the engine might be rich already, so the problem might have something to do with your prop selection. Even though the 13 x 6 has worked well on other models, you might want to try a different prop on the new plane. Different airframes react differently to motor/prop combinations, and you may find a different pitch or size on your prop will give you the perfomance you expect.
This is all assuming that the new Sukhoi isn't noticably heavier than the other planes you've had this engine mounted on. If it is, that, of course, will affect how much "punch" it has.
David
Sometimes you'll see an engine leaning out in flight because the air is rushing into the carb at an increased rate due to the speed of the plane compared to when it's just sitting on the ground. So, as a general rule, it's best to set the high end slightly rich to compensate for this phenonmenon. You might try richening the high end slightly and see if the performance improves.
But you said if anything you think the engine might be rich already, so the problem might have something to do with your prop selection. Even though the 13 x 6 has worked well on other models, you might want to try a different prop on the new plane. Different airframes react differently to motor/prop combinations, and you may find a different pitch or size on your prop will give you the perfomance you expect.
This is all assuming that the new Sukhoi isn't noticably heavier than the other planes you've had this engine mounted on. If it is, that, of course, will affect how much "punch" it has.
David
08-26-2008 | 01:28 PM
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From: Weddington,
NC
RE: Problem caused by cowl ?
Hello Belgian (from another Belgian fellow in Florida!)
I had similar problem with my YS63 (old one) in a Flip3D. It was getting warm inside the cowling and the problem resides in the regulator getting stuck and dying while hovering, with the negative results it produces.
I envisioned creating an airflow over the regulator but ended-up removing the cowling completely, since then no problem.
That's why the newer YS63 (and others) moved the regulator to the front where it has plenty of air.
Hope it helps
Ben
I had similar problem with my YS63 (old one) in a Flip3D. It was getting warm inside the cowling and the problem resides in the regulator getting stuck and dying while hovering, with the negative results it produces.
I envisioned creating an airflow over the regulator but ended-up removing the cowling completely, since then no problem.
That's why the newer YS63 (and others) moved the regulator to the front where it has plenty of air.
Hope it helps
Ben
08-26-2008 | 06:14 PM
#5
RE: Problem caused by cowl ?
Take the cowl off and fly it. See if it still flys the same or if it improves. If it's better, you've got an air flow situation that needs to be worked on. As others have said, try some different props too.
Paul
Paul
08-26-2008 | 08:09 PM
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RE: Problem caused by cowl ?
I have to agree with a few of the posts here. The Sukoi has a pretty big cowl opening and is draggy. The engine may just be battling a larger load.
First pull the cowl and give it a go. The airflow within the cowl at airspeed may be starving the carb inlet. If the cowl off does not give you any gain then you might want to try a few different props.
First pull the cowl and give it a go. The airflow within the cowl at airspeed may be starving the carb inlet. If the cowl off does not give you any gain then you might want to try a few different props.
08-26-2008 | 08:21 PM
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From: Springtown,
TX
RE: Problem caused by cowl ?
Remember, you need at least twice the area for air to leave the cowl as you need for it to enter.
Also, engines do tend to lean out in the air, no matter where their carb is. However, it is due to the fact that they will gain around 300 or so RPM's when they unload, so sometimes they go a bit lean when this happens. That is why you want to richen it up by about 300 RPM's from peak before you fly it.
Also, engines do tend to lean out in the air, no matter where their carb is. However, it is due to the fact that they will gain around 300 or so RPM's when they unload, so sometimes they go a bit lean when this happens. That is why you want to richen it up by about 300 RPM's from peak before you fly it.
09-01-2008 | 10:01 AM
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From: Wieze, BELGIUM
RE: Problem caused by cowl ?
Well my problem is solved ! It turns out as suspected. The cowl caused the issue. It looks like there was a kind of 'vacuum' within the cowl on the carburetor's side (engine mounted sideways) so the engine started running 'rich' Solution was to simply (dremel) cut a few slots on the carb's side of the cowl allowing the engine to "breath". Never before had this kind of issue. I had engines overheating due to bad cooling inside a cowl several times before, but never this. You learn something new every day ;-)) even at 51.
