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aerobiz1(at)gmail.com
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 Posted: Sun Jun 26, 2011 3:19 pm Post subject: Aircraft angle of Incidence in flight and engine cooling |
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Hi Jeff,
The angle of incidence, or more correctly, the angle of the relative airflow will certainly have an effect on cooling. It is well known that the angle of a radiator in a watercooled installation is important, and the same can be said with cowlings on aircooled engines. As you have noticed, the inlet ramps in the cowl may not be efficient at all speeds, and climb angle is one that we tend to overlook. We should look at having the most direct airflow path in the climb attiitude rather than in cruise when engine temps are an issue.
If your aircraft is flying in a nose up attitude in cruise, you may have a trim or weight and balance issue, or just maybe you were flying slower than normal when the pic was taken. Something to look at.
Cheers
Martin
On Mon, Jun 27, 2011 at 8:16 AM, Jeffrey J Paris <jeffrey-j-paris(at)excite.com (jeffrey-j-paris(at)excite.com)> wrote:
[quote] Wizards!
Question: Could the angle of incidence in flight effect the ability of an engine to cool? I ask this because, I truly believe that I have my Bing Carb dialed in as far as EGTs, but in cruise I still have pesky CHT issues on cylinder 2,3,4 and #4 is always in the 315F range. In a sustained climb I, things head for toast quickly!
When we purchased our FWF kit from Jabiru USA early version, we figured that they had everything figured out. Obviously, in my case although we followed the install instructions to a tee, we still are playing with all things engine and cowl. In terms of the angle of incidence, my friend and I went flying the other day and he took a picture of me and I believe it looks as if that when in cruise my nose of the aircraft is up, which might account for some sort of impeded airflow into the cowl. I'm asking this question, becasue when we all obviously point the nose down in descent we get better airrflow and CHT's tend to come down.
Any thoughts on this matter.
CAVU,
Jeff Paris Ni196ZP Jab 3300 Ch601XLB N127ZP Jab 3300 Eurpoa Monowheel in drydock
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matronics(at)rtist.nl
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| Posted: Sun Jun 26, 2011 11:16 pm Post subject: Aircraft angle of Incidence in flight and engine cooling |
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Jeff,
With 315F in cruise I would be very nervous, that's not good.
Grab a copy of the installation manual for your engine at www.jabiru.net.au. This manual has an entire chapter devoted to engine cooling, including the impact of airplane orientation with regards to the airstream. The manual offers methods to measure the effectiveness of your installation, as well as hints on how to improve it.
While at it, get a copy of JSB016-1 service bulletin, which describes how to add cowl lips to improve cooling performance.
What kind of prop do you use? Some do not produce any airflow at the root of the prop.
Rob
On 6/27/2011 12:16 AM, Jeffrey J Paris wrote: [quote] Wizards!
Question: Could the angle of incidence in flight effect the ability of an engine to cool? I ask this because, I truly believe that I have my Bing Carb dialed in as far as EGTs, but in cruise I still have pesky CHT issues on cylinder 2,3,4 and #4 is always in the 315F range. In a sustained climb I, things head for toast quickly!
When we purchased our FWF kit from Jabiru USA early version, we figured that they had everything figured out. Obviously, in my case although we followed the install instructions to a tee, we still are playing with all things engine and cowl. In terms of the angle of incidence, my friend and I went flying the other day and he took a picture of me and I believe it looks as if that when in cruise my nose of the aircraft is up, which might account for some sort of impeded airflow into the cowl. I'm asking this question, becasue when we all obviously point the nose down in descent we get better airrflow and CHT's tend to come down.
Any thoughts on this matter.
CAVU,
Jeff Paris Ni196ZP Jab 3300 Ch601XLB N127ZP Jab 3300 Eurpoa Monowheel in drydock
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