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ernest(at)flmitigation.co
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 Posted: Mon Dec 06, 2010 3:41 am Post subject: Cowling intake and exit |
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Is there a certain ratio that is optimum for cooling and reduction of drag between the intake and outlet for airflow over the engine? Also, any certain dimensions to the inlets and outlet?
Thanks,
Ernest Hale
N540HB
On 12/5/10 6:46 PM, "Jim Ayers" <[url=lessdragprod(at)aol.com]lessdragprod(at)aol.com[/url]> wrote:
[quote]Hi John,
I didn't know that you've flown one of these Rocket 4 blade MT Propellers. 
Rainer, in Germany, is likely going to be limited to 2500 RPM maximum.
An F-1 customer with the 3 blade Rocket propeller says the 4 blade MT Rocket propeller is 2 knots sower at 4,000'.
But faster at 9,500' and 10,500'.
John. I know this doesn't work for your typical flight. The highest altitude you reach being when you climb to pattern altitude.
Jim Ayers
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smokyray(at)rocketmail.co
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| Posted: Mon Dec 06, 2010 8:11 am Post subject: Cowling intake and exit |
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Ernest,
Johns stock HR2 cowling works extremely well for cooling and efficiency right out of the box. I have always used 1:1.2 for entry/exit ratio. Remember when you measure the exit to consider the exhaust pipes using some of the area. Most of my flying is in hot weather so I cut a large U in my lower cowling lowering my CHTs in climb below 350 and 300 in cruise and no noticeable speed loss. I estimate my current ratio at 1:1.5 entry/exit. I normally cruise at 20"/2350 RPM 180 knots true at 10.5 GPH using electronic ignition, GAMI injectors 2 blade Hartzell D twist and swept wing tips. I use a larger tire for my rough home strip yet can reach 220 knots in level flight. A truly wonderful airplane!
Smokey
Sent from my iPhone
On Dec 6, 2010, at 6:37, Ernest Hale <ernest(at)flmitigation.com (ernest(at)flmitigation.com)> wrote:
[quote] Is there a certain ratio that is optimum for cooling and reduction of drag between the intake and outlet for airflow over the engine? Also, any certain dimensions to the inlets and outlet?
Thanks,
Ernest Hale
N540HB
On 12/5/10 6:46 PM, "Jim Ayers" <lessdragprod(at)aol.com (lessdragprod(at)aol.com)> wrote:
[quote]Hi John,
I didn't know that you've flown one of these Rocket 4 blade MT Propellers.
Rainer, in Germany, is likely going to be limited to 2500 RPM maximum.
An F-1 customer with the 3 blade Rocket propeller says the 4 blade MT Rocket propeller is 2 knots sower at 4,000'.
But faster at 9,500' and 10,500'.
John. I know this doesn't work for your typical flight. The highest altitude you reach being when you climb to pattern altitude.
Jim Ayers
--
| | - The Matronics Rocket-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Rocket-List |
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ernest(at)flmitigation.co
Guest
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| Posted: Mon Dec 06, 2010 3:43 pm Post subject: Cowling intake and exit |
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Thanks, great information.
On 12/6/10 11:08 AM, "Rob Ray" <[url=smokyray(at)rocketmail.com]smokyray(at)rocketmail.com[/url]> wrote:
[quote]Ernest,
Johns stock HR2 cowling works extremely well for cooling and efficiency right out of the box. I have always used 1:1.2 for entry/exit ratio. Remember when you measure the exit to consider the exhaust pipes using some of the area. Most of my flying is in hot weather so I cut a large U in my lower cowling lowering my CHTs in climb below 350 and 300 in cruise and no noticeable speed loss. I estimate my current ratio at 1:1.5 entry/exit. I normally cruise at 20"/2350 RPM 180 knots true at 10.5 GPH using electronic ignition, GAMI injectors 2 blade Hartzell D twist and swept wing tips. I use a larger tire for my rough home strip yet can reach 220 knots in level flight. A truly wonderful airplane!
Smokey
Sent from my iPhone
On Dec 6, 2010, at 6:37, Ernest Hale <[url=ernest(at)flmitigation.com]ernest(at)flmitigation.com[/url]> wrote:
[quote]Is there a certain ratio that is optimum for cooling and reduction of drag between the intake and outlet for airflow over the engine? Also, any certain dimensions to the inlets and outlet?
Thanks,
Ernest Hale
N540HB
On 12/5/10 6:46 PM, "Jim Ayers" <mailto:lessdragprod(at)aol.com (lessdragprod(at)aol.com)> > wrote:
[quote]Hi John,
I didn't know that you've flown one of these Rocket 4 blade MT Propellers.
Rainer, in Germany, is likely going to be limited to 2500 RPM maximum.
An F-1 customer with the 3 blade Rocket propeller says the 4 blade MT Rocket propeller is 2 knots sower at 4,000'.
But faster at 9,500' and 10,500'.
John. I know this doesn't work for your typical flight. The highest altitude you reach being when you climb to pattern altitude.
Jim Ayers
--
| | - The Matronics Rocket-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Rocket-List |
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