Engine cowl questions from a relative beginner.
08-13-2006 | 09:20 PM
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From: Wallingford,
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Engine cowl questions from a relative beginner.
Hello,
I'm a relative beginner, so I have a few questions regarding mounting an engine behind a cowl.
I'm currently building a Graupner Extra 300S with a Super Tigre 90. This is my first plane with an engine cowl. I had to buy a Slimline Pitts muffler in order to fit it behind the cowl. I cut clearance around the engine head, muffler, etc, but even then, it's still pretty difficult to put the cowl on. I have a few questions regarding the engine/cowl installation:
1. How do I fill up the fuel tank? In my other planes, I remove the fuel line from the muffler and the carb. I fill through the carb until it starts to come out the muffler line. I don't see how I'll be able to get to either of these lines with the cowl on, so how do I fill (maybe a 3rd line), and how do I know the tank is full?
2. Is it unusual to have to remove landing gear to be able to fit the cowl on the plane? The instructions mentioned to cut 4 holes in the cowl for attaching the landing gear screws. I didn't realize why until I tried to put the cowl on with the landing gear still mounted. It seems like the only way to fit the cowl without cutting out large pieces of it is to remove the landing gear, put the cowl on, and then re-attach the landing gear.
3. How often do people generally take the cowl off once it's mounted? With my current plane I clean around the engine / engine mount pretty often. If a cowl screws onto the plane, then how can I clean around the engine? Do I just fly it 10 times before removing the cowl to clean?
I think that pretty much covers it. Any help would be appreciated.
Thanks,
Patrick
I'm a relative beginner, so I have a few questions regarding mounting an engine behind a cowl.
I'm currently building a Graupner Extra 300S with a Super Tigre 90. This is my first plane with an engine cowl. I had to buy a Slimline Pitts muffler in order to fit it behind the cowl. I cut clearance around the engine head, muffler, etc, but even then, it's still pretty difficult to put the cowl on. I have a few questions regarding the engine/cowl installation:
1. How do I fill up the fuel tank? In my other planes, I remove the fuel line from the muffler and the carb. I fill through the carb until it starts to come out the muffler line. I don't see how I'll be able to get to either of these lines with the cowl on, so how do I fill (maybe a 3rd line), and how do I know the tank is full?
2. Is it unusual to have to remove landing gear to be able to fit the cowl on the plane? The instructions mentioned to cut 4 holes in the cowl for attaching the landing gear screws. I didn't realize why until I tried to put the cowl on with the landing gear still mounted. It seems like the only way to fit the cowl without cutting out large pieces of it is to remove the landing gear, put the cowl on, and then re-attach the landing gear.
3. How often do people generally take the cowl off once it's mounted? With my current plane I clean around the engine / engine mount pretty often. If a cowl screws onto the plane, then how can I clean around the engine? Do I just fly it 10 times before removing the cowl to clean?
I think that pretty much covers it. Any help would be appreciated.
Thanks,
Patrick
08-13-2006 | 10:33 PM
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From: va beach,
VA
RE: Engine cowl questions from a relative beginner.
there is a lot of different ways to fill the tank one way is a three line with fuel dot,i run my pressure line to the bottom with a piece of brass fuel tube between the tank and muffler i disconnect the pressure line when I'm filling the tank when i see fuel i reconnect,some people just let fuel run out of the muffler.
as far as your landing gear I'm not familiar with that model but I'm sure you could figure out a way to remove the cowl without the landing gear,i don't have to remove my cowls often unless something breaks.when i clean my cowled engines i just use alcohol in a spray bottle and then blow everything off with an air hose.
as far as your landing gear I'm not familiar with that model but I'm sure you could figure out a way to remove the cowl without the landing gear,i don't have to remove my cowls often unless something breaks.when i clean my cowled engines i just use alcohol in a spray bottle and then blow everything off with an air hose.
08-14-2006 | 09:25 AM
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From: FrederickMD
RE: Engine cowl questions from a relative beginner.
To fuel my CAP 232, I have a third (fill) line in my fuel tank. I put a "T" connector in the pressure line. Both these lines have a plug. To fuel, I make sure the throttle is completely closed, and connect the fuel fill line from the pump to the fuel fill line to the plane. I connect the fuel pressure line back to my fuel bottle vent. When the tank is full, the overflow from the pressure (vent) line drains out the overflow back to the fuel bottle. There is usually some that goes to the muffler, but the engine is mounted sideways (muffler down), so there is no risk of flooding the engine from the overflow. I have found that if I'm careful, and leave the throttle partially open, the pressure from filling the tank will also prime the engine.
I have tried using a hemostat to pinch the pressure line from the muffler to prevent fuel flow out the muffler, but have had mixed results (torn fuel line, hemostat slips off, etc).
Also, make sure you have sufficient airflow through the cowl by ensuring the exit hole area is larger than the inlet holes at the front.
Good Luck!
Brad
I have tried using a hemostat to pinch the pressure line from the muffler to prevent fuel flow out the muffler, but have had mixed results (torn fuel line, hemostat slips off, etc).
Also, make sure you have sufficient airflow through the cowl by ensuring the exit hole area is larger than the inlet holes at the front.
Good Luck!
Brad
08-14-2006 | 09:31 AM
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RE: Engine cowl questions from a relative beginner.
ORIGINAL: ptuxbury
Hello,
I'm a relative beginner, so I have a few questions regarding mounting an engine behind a cowl.
I'm currently building a Graupner Extra 300S with a Super Tigre 90. This is my first plane with an engine cowl. I had to buy a Slimline Pitts muffler in order to fit it behind the cowl. I cut clearance around the engine head, muffler, etc, but even then, it's still pretty difficult to put the cowl on. I have a few questions regarding the engine/cowl installation:
1. How do I fill up the fuel tank? In my other planes, I remove the fuel line from the muffler and the carb. I fill through the carb until it starts to come out the muffler line. I don't see how I'll be able to get to either of these lines with the cowl on, so how do I fill (maybe a 3rd line), and how do I know the tank is full?
>The 2 ways most people use most often is a fueling "valve" and 3rd line.
>My experience with the fueling valves has not been good. I have not had
>one make it a season without leaking. I use the 3rd line method with 2
>clunks in the tank. Most people wait until they see some fuel come out of
>the muffler, then they know the tank is full.
2. Is it unusual to have to remove landing gear to be able to fit the cowl on the plane? The instructions mentioned to cut 4 holes in the cowl for attaching the landing gear screws. I didn't realize why until I tried to put the cowl on with the landing gear still mounted. It seems like the only way to fit the cowl without cutting out large pieces of it is to remove the landing gear, put the cowl on, and then re-attach the landing gear.
>That does sound unusual to me, however I am not familiar with your
>plane. I suggest cutting the cowl to fit over/around the landing gear.
3. How often do people generally take the cowl off once it's mounted? With my current plane I clean around the engine / engine mount pretty often. If a cowl screws onto the plane, then how can I clean around the engine? Do I just fly it 10 times before removing the cowl to clean?
>I normally leave the cowl off and fly the plane several times so that
>I can fine tune the engine (if needed). Once the engine is fine tuned
>(low end) I put the cowl on. As for cleaning, the inside of the cowl
>USUALLY stays relatively clean. The outside I clean with Windex.
>
>As a side note - To prevent/minimize overheating of the engine you
>should have a 3:1 ratio for cooling. For every 1 square inch of air inlet
>you should have 3" square inches of air outlet.
I think that pretty much covers it. Any help would be appreciated.
Thanks,
Patrick
Hello,
I'm a relative beginner, so I have a few questions regarding mounting an engine behind a cowl.
I'm currently building a Graupner Extra 300S with a Super Tigre 90. This is my first plane with an engine cowl. I had to buy a Slimline Pitts muffler in order to fit it behind the cowl. I cut clearance around the engine head, muffler, etc, but even then, it's still pretty difficult to put the cowl on. I have a few questions regarding the engine/cowl installation:
1. How do I fill up the fuel tank? In my other planes, I remove the fuel line from the muffler and the carb. I fill through the carb until it starts to come out the muffler line. I don't see how I'll be able to get to either of these lines with the cowl on, so how do I fill (maybe a 3rd line), and how do I know the tank is full?
>The 2 ways most people use most often is a fueling "valve" and 3rd line.
>My experience with the fueling valves has not been good. I have not had
>one make it a season without leaking. I use the 3rd line method with 2
>clunks in the tank. Most people wait until they see some fuel come out of
>the muffler, then they know the tank is full.
2. Is it unusual to have to remove landing gear to be able to fit the cowl on the plane? The instructions mentioned to cut 4 holes in the cowl for attaching the landing gear screws. I didn't realize why until I tried to put the cowl on with the landing gear still mounted. It seems like the only way to fit the cowl without cutting out large pieces of it is to remove the landing gear, put the cowl on, and then re-attach the landing gear.
>That does sound unusual to me, however I am not familiar with your
>plane. I suggest cutting the cowl to fit over/around the landing gear.
3. How often do people generally take the cowl off once it's mounted? With my current plane I clean around the engine / engine mount pretty often. If a cowl screws onto the plane, then how can I clean around the engine? Do I just fly it 10 times before removing the cowl to clean?
>I normally leave the cowl off and fly the plane several times so that
>I can fine tune the engine (if needed). Once the engine is fine tuned
>(low end) I put the cowl on. As for cleaning, the inside of the cowl
>USUALLY stays relatively clean. The outside I clean with Windex.
>
>As a side note - To prevent/minimize overheating of the engine you
>should have a 3:1 ratio for cooling. For every 1 square inch of air inlet
>you should have 3" square inches of air outlet.
I think that pretty much covers it. Any help would be appreciated.
Thanks,
Patrick
08-14-2006 | 11:30 AM
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From: Guelph,
ON,
RE: Engine cowl questions from a relative beginner.
ORIGINAL: ptuxbury
1. How do I fill up the fuel tank? In my other planes, I remove the fuel line from the muffler and the carb. I fill through the carb until it starts to come out the muffler line. I don't see how I'll be able to get to either of these lines with the cowl on, so how do I fill (maybe a 3rd line), and how do I know the tank is full?
1. How do I fill up the fuel tank? In my other planes, I remove the fuel line from the muffler and the carb. I fill through the carb until it starts to come out the muffler line. I don't see how I'll be able to get to either of these lines with the cowl on, so how do I fill (maybe a 3rd line), and how do I know the tank is full?
08-14-2006 | 12:17 PM
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From: Tracy,
CA
RE: Engine cowl questions from a relative beginner.
I like to use a 3 line fuel system & a fuel dot that mounts in the side of the cowl. You simply pull the fill line out of the fuel dot a couple of inches, fill the tank then return the fuel line back into the fuel dot. It is a very clean looking installation & it is problem free. I use them on all my cowled aircraft. Here is a link to a fuel dot.
http://www.horizonhobby.com/Products...?ProdID=HAN115
Note: I don't use the T, I use a 3 line system so the fill line goes straight to the tank. I put a clunk on this line too so that it can be used for emptying the tank as well as filling it. I hope this helps.
http://www.horizonhobby.com/Products...?ProdID=HAN115
Note: I don't use the T, I use a 3 line system so the fill line goes straight to the tank. I put a clunk on this line too so that it can be used for emptying the tank as well as filling it. I hope this helps.
08-22-2006 | 10:46 PM
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From: Wallingford,
CT
RE: Engine cowl questions from a relative beginner.
Thanks for the great advice, everyone. I have one last question that I just thought about...
Normally when I am getting ready to fly, I adjust the high end needle valve. The way I know I've leaned it out properly is to pinch the tubing that goes into the carb and listen for the engine to speed up. How do I accomplish this if all the fuel tubing is underneath the cowl?
I'm thinking I may have to run a little bit outside the cowl just so I can pinch it.
Thanks,
Patrick
Normally when I am getting ready to fly, I adjust the high end needle valve. The way I know I've leaned it out properly is to pinch the tubing that goes into the carb and listen for the engine to speed up. How do I accomplish this if all the fuel tubing is underneath the cowl?
I'm thinking I may have to run a little bit outside the cowl just so I can pinch it.
Thanks,
Patrick
08-23-2006 | 09:45 AM
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RE: Engine cowl questions from a relative beginner.
The "pinch" test is better suited to low-end adjusment.
For the high-end, turn the needle to the lean side (Closing it) until you hear it peak. Keep turning till it goes sick, then turn it back to where it sounded good.
Now at full throttle, have someone point the nose straight up. If it goes sick, you need to richen it a few clicks.
Keep doing this until it sounds the same or better when pointed up.
For the high-end, turn the needle to the lean side (Closing it) until you hear it peak. Keep turning till it goes sick, then turn it back to where it sounded good.
Now at full throttle, have someone point the nose straight up. If it goes sick, you need to richen it a few clicks.
Keep doing this until it sounds the same or better when pointed up.
