How does a gas engine act when hot?
07-25-2013, 02:09 PM
#27
RE: How does a gas engine act when hot?
You say you have a tight engine installation. I have some questions and a few comments for you
1. Ensure the airflow exit to your cowl is bigger than the inlet side.
2. What engine are you using?
3. What aircraft are you talking about with the tight cowl?
Comments:
1. If the engine is a Zenoah: Understand that the Zenoah engine was designed to be used in factory applications and as such it is more tolerant to heat than most other gas engines in general. The Zenoah series is ideal for tight applications as long as you get cooling air over the head and cut the cowl as stated above on item #1.
2. Gas engines over glow engines are more tolerant of heat as well.
3. If the engine is expected to run "Hot" enrichen the high end needle a tad to prevent sagging upon full throttle applications and adjust as required to achieve a smooth transition when the engine is running within the cowl and "hot".
4. You can also purchase some screen material and cut the cowl to accomodate them. This will allow more airflow by installing the screens on the inner side of the cowl. I usually install 2 on the top and 2 on the bottom and paint the screens to match the cowl. These look cool and also cool the engine as well. Here's how. Cut 2 slits forward and aft about 2 to 3 inches long by about 1/4" to 1/2" wide the clean and debur the cowl. Use 5 or 15 minute epoxy on the screen edges and when cured use spray paint to paint the screens. Do this on top and bottom and as stated on item #1 ensure the inlet is smaller than the the exit area of the cowl and you should be good to go.
Regards
Glenn Williams
07-25-2013, 05:21 PM
#29
RE: How does a gas engine act when hot?
ORIGINAL: willig10
You say you have a tight engine installation. I have some questions and a few comments for you
1. Ensure the airflow exit to your cowl is bigger than the inlet side.
2. What engine are you using?
3. What aircraft are you talking about with the tight cowl?
Comments:
1. If the engine is a Zenoah: Understand that the Zenoah engine was designed to be used in factory applications and as such it is more tolerant to heat than most other gas engines in general. The Zenoah series is ideal for tight applications as long as you get cooling air over the head and cut the cowl as stated above on item #1.
2. Gas engines over glow engines are more tolerant of heat as well.
3. If the engine is expected to run "Hot" enrichen the high end needle a tad to prevent sagging upon full throttle applications and adjust as required to achieve a smooth transition when the engine is running within the cowl and "hot".
4. You can also purchase some screen materialand cut the cowl to accomodate them. This will allow more airflow by installing the screens on the inner side of the cowl. I usually install 2 on the top and 2 on the bottomand paint the screensto match the cowl. These look cool and also cool the engine as well. Here's how. Cut 2 slits forward and aft about 2 to 3 inches long by about 1/4" to 1/2" wide the clean and debur the cowl. Use 5 or 15 minute epoxy on the screen edges and when cured use spray paint to paint the screens. Do this on top and bottom and as stated on item #1 ensure the inlet is smaller than the the exit area of the cowl and you should be good to go.
Regards
Glenn Williams
You say you have a tight engine installation. I have some questions and a few comments for you
1. Ensure the airflow exit to your cowl is bigger than the inlet side.
2. What engine are you using?
3. What aircraft are you talking about with the tight cowl?
Comments:
1. If the engine is a Zenoah: Understand that the Zenoah engine was designed to be used in factory applications and as such it is more tolerant to heat than most other gas engines in general. The Zenoah series is ideal for tight applications as long as you get cooling air over the head and cut the cowl as stated above on item #1.
2. Gas engines over glow engines are more tolerant of heat as well.
3. If the engine is expected to run "Hot" enrichen the high end needle a tad to prevent sagging upon full throttle applications and adjust as required to achieve a smooth transition when the engine is running within the cowl and "hot".
4. You can also purchase some screen materialand cut the cowl to accomodate them. This will allow more airflow by installing the screens on the inner side of the cowl. I usually install 2 on the top and 2 on the bottomand paint the screensto match the cowl. These look cool and also cool the engine as well. Here's how. Cut 2 slits forward and aft about 2 to 3 inches long by about 1/4" to 1/2" wide the clean and debur the cowl. Use 5 or 15 minute epoxy on the screen edges and when cured use spray paint to paint the screens. Do this on top and bottom and as stated on item #1 ensure the inlet is smaller than the the exit area of the cowl and you should be good to go.
Regards
Glenn Williams
07-25-2013, 05:25 PM
#30
Senior Member
RE: How does a gas engine act when hot?
ORIGINAL: acerc
MTK add a link to your pattern forum.
MTK add a link to your pattern forum.
07-25-2013, 05:28 PM
#31
Senior Member
RE: How does a gas engine act when hot?
http://www.rcuniverse.com/forum/m_10...6/tm.htmAround the middle of the page you should see the chin cowl progress. Later, I show it finishedSorry fellas I double posted. I'm having problems with this site
07-25-2013, 06:07 PM
#32
Join Date: Sep 2006
Location: The Sunshine state, when it's not raining!
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RE: How does a gas engine act when hot?
You know Matt, that is the first time I have seen your work. Very impressive and worthy of further reading. I have added you to my list of guys to search and follow, read up on and learn.
07-25-2013, 06:38 PM
#33
RE: How does a gas engine act when hot?
OK, first of all, I want to thank everyone who posted info, as I think this is what makes RCU so great.
Now, I want to get things back on track. First of all, I did not know if I had a problem or not. I thought that I could possibly have one though, so I was originally asking for warning signs of overheating.
To those that said my install was doomed, sorry, but you were wrong. Mounting the engine inverted is not an option as you would have to cut the landing gear mounting wire and this does not work. Been there done that!
I made the first flight with the cowling off, and it worked perfectly, No mixture changes or sagging on vertical climbs. I made a second flight just to be sure everything was still going well, now that I was comfortable with the trim and such. This was a much longer flight. Probably around 10 min. I was having fun!
Then I added the cowl for the 3rd flight. I got a bunch of altitude just in case and flew it around. I varied the throttle settings, but also stayed at full throttle for a while as well. I had no mixture changes or sagging in verticals and loops. Yep, got me an awesome plane. It needed almost no trim either as a bonus!
I think the louvers are helping a bunch, but most of the heat is going into the cockpit which is what I thought. Poor Lothar!
Now, I want to get things back on track. First of all, I did not know if I had a problem or not. I thought that I could possibly have one though, so I was originally asking for warning signs of overheating.
To those that said my install was doomed, sorry, but you were wrong. Mounting the engine inverted is not an option as you would have to cut the landing gear mounting wire and this does not work. Been there done that!
I made the first flight with the cowling off, and it worked perfectly, No mixture changes or sagging on vertical climbs. I made a second flight just to be sure everything was still going well, now that I was comfortable with the trim and such. This was a much longer flight. Probably around 10 min. I was having fun!
Then I added the cowl for the 3rd flight. I got a bunch of altitude just in case and flew it around. I varied the throttle settings, but also stayed at full throttle for a while as well. I had no mixture changes or sagging in verticals and loops. Yep, got me an awesome plane. It needed almost no trim either as a bonus!
I think the louvers are helping a bunch, but most of the heat is going into the cockpit which is what I thought. Poor Lothar!
07-25-2013, 08:56 PM
#36
RE: How does a gas engine act when hot?
No not me. I'm not much of a scale guy other then my warbird racers and IMAC airplanes. Those are stand in Egypt scale LOL. I can appreciate you guys that can build one up with the correct covering and paint though. Making a scale model look authentic like that takes some skills that not many have.
07-25-2013, 09:13 PM
#37
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RE: How does a gas engine act when hot?
ORIGINAL: MTK
Robert, Ernie and all,start here http://www.rcuniverse.com/forum/m_10...mpage_6/tm.htm where the chin cowl is still in build stage. Later in the last page I show it finished
ORIGINAL: acerc
MTK add a link to your pattern forum.
MTK add a link to your pattern forum.
07-25-2013, 09:15 PM
#38
Join Date: Jul 2002
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RE: How does a gas engine act when hot?
ORIGINAL: MTK
Robert, Ernie and all,start here http://www.rcuniverse.com/forum/m_10...mpage_6/tm.htm where the chin cowl is still in build stage. Later in the last page I show it finished
ORIGINAL: acerc
MTK add a link to your pattern forum.
MTK add a link to your pattern forum.
07-26-2013, 05:38 AM
#39
Senior Member
RE: How does a gas engine act when hot?
Thank you Robert and Ernie....I've been at it some 46 years and taught myself a few things along the way. I try to help my fellow modelers where I can and as much as I am allowed....
Now, lets see if we cant help VG get his crate cooling better
Now, lets see if we cant help VG get his crate cooling better
