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jesse(at)saintaviation.co
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 Posted: Thu Mar 27, 2014 7:00 am Post subject: James Cowl and cooling |
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I know there has been discussion about this in the past, but I am wondering what conclusions were made. I am working on an RV-10 that has the James cowl and plenum and the 5" inlet rings. What was the final verdict on these? I know we haven't heard from Deems in a while. Anybody else have some info on this?
Thanks.
Jesse Saint
Saint Aviation, Inc.
jesse(at)saintaviation.com
C: 352-427-0285
F: 815-377-3694
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carl.froehlich(at)verizon
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| Posted: Thu Mar 27, 2014 7:44 am Post subject: James Cowl and cooling |
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150 hours on a James Cowl and plenum. I am happy with the decision and
would do it again. I will be putting a James Cowl on the next project as
well (RV- .
There is no magic here, you reduce drag by better management of engine
cooling (as in you have less lbm of cooling air coming). For the RV-10
built for cruise, this makes sense. If you are building an RV-10 for
stunning climb at low airspeed, the James Cowl in not the way to go. On a
hot day and heavy, I do extended climbs above 125 kts. This still provides
1000fpm+ but is much lower than what I could get if the nose is pointed more
skyward. This tradeoff provides 170kt cruise at LOP, 2350 RPM and MP
dependent on altitude. CHTs are all below 350 in cruise on a hot day. Note
this data is after cylinder injector balancing. I'm using a stock IO-540
from Vans (not a fire breather) and made a few under the cowl modes to fix
inherent RV-10 engine cooling issues (e.g. oil cooler mounting and cabin
heat exit path when cabin heat is off).
There is more work involved than the stock Van's cowl. If you are looking
for simple, stay with the stock cowl.
As a side note, the RV-10 James Cowl is no longer available. Will James got
too much noise from the RV community as a few of the early adopters had
issues.
Carl
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flying-nut(at)cfl.rr.com
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| Posted: Thu Mar 27, 2014 9:07 am Post subject: James Cowl and cooling |
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Not a direct James issue, but discussions I've had pointed out that the
forward side of #2 cylinder and aft side of #5 cylinder (Lycoming) don't
get much airflow because the height of the fins in this area are very
short .... not much air gets by. Other comments on my lists have people
putting washers between the cylinder and the baffle to get more air
flow. I'm interested as well because I'm looking at the James plenum
and round inlets on a Vans cowl.
Linn ...... painting the interior
On 3/27/2014 10:46 AM, Jesse Saint wrote:
| Quote: |
I know there has been discussion about this in the past, but I am wondering what conclusions were made. I am working on an RV-10 that has the James cowl and plenum and the 5" inlet rings. What was the final verdict on these? I know we haven't heard from Deems in a while. Anybody else have some info on this?
Thanks.
Jesse Saint
Saint Aviation, Inc.
jesse(at)saintaviation.com
C: 352-427-0285
F: 815-377-3694
-----
No virus found in this message.
Checked by AVG - www.avg.com
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Deems Davis
Joined: 09 Jan 2006
Posts: 925
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| Posted: Thu Mar 27, 2014 9:30 am Post subject: James Cowl and cooling |
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Update
I have had 3 issues with the James Cowl:
1. I had to modify the cowl to accept a Ram Air Fuel Servo Intake (Will fixed this on later cowls IIRC)
2. I couldn't run LOP without adding pressurized Injector nozzles (not cheap)
3. High OIL and engine temps (I live in AZ so for 5 months of the year I Really had to watch the temps on Climb)
Last year I made a modification that REALLY made a difference for me.
I fabricated a fiberglass Ram Air intake and mounted it on the bottom of the cowl, replacing the nose gear leg slot cover that fits in front of the nose gear. (I have 3bld and so this is extended) It. I used the same nutplates to attach it so there was no modification to the cowl itself. It connects to a 3.5" scat tube. I blocked off the oil cooler air intake on the baffling behind the #6 cyl, and fabricated from fiberglass an ~ 120 degree reducer elbow that connects the scat tube to the top of the oil cooler. The result have been super. My #6 cyl was always my hottest and now its in the middle of the pack (20-30 deg spread). Oil Temps had to be carefully managed in Summer to keep below 220, Now, they rarely exceed 200 in the summer on normal 100-120kt climb and run between 180-190 depending on OAT. CHT across the board dropped 30-40 degrees. I can run LOP down to 10 gph without balanced injectors.
What I think I learned....
1. The placement of the oil cooler air intake on the rear of the baffles w/ the James cowl is too low, and it steals cooling air for the #6 (Someone either Robin Marks or Ed Hayden tried modifying the SJ plenum in this area and it didn't make much of a difference in Oil Temps).
2. The inlet rings on the SJ cowl are Too Small and don't allow enough air to both cool the engine and cool the oil. (If you think about it they are the same size as for the 4 cyl. Alan (?) demonstrated this when he modified his cowl and plenum and fabricated bigger intake rings.
3. I think that if I had made the above ram air intake and installed it before I began experimenting w/ LOP that I may have avoided the need for the turbo nozzle rails. (I'm not taking them off to find out)
I LOVE the appearance of the SJ cowl
I think I posted some pics of this mod last year.
[quote][b]
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Kelly McMullen
Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ
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| Posted: Thu Mar 27, 2014 3:17 pm Post subject: James Cowl and cooling |
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The issue with lack of cooling fins on the intake port side of Lycoming cylinder heads was probably best documented by the Cardinal Flyers Online group. IIRC they worked with George Braley of GAMI to solve the issue. It involved making a space of at least 1/8" between the baffle and the cylinder head fins (which actually don't allow any air through. Doing that produced approx. 30 degree CHT drop on Cardinal 4 cyl O or IO-360s.
On Thu, Mar 27, 2014 at 10:06 AM, Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)> wrote:
| Quote: | --> RV10-List message posted by: Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)>
Not a direct James issue, but discussions I've had pointed out that the forward side of #2 cylinder and aft side of #5 cylinder (Lycoming) don't get much airflow because the height of the fins in this area are very short .... not much air gets by. Other comments on my lists have people putting washers between the cylinder and the baffle to get more air flow. I'm interested as well because I'm looking at the James plenum and round inlets on a Vans cowl.
Linn ...... painting the interior
On 3/27/2014 10:46 AM, Jesse Saint wrote:
| Quote: | --> RV10-List message posted by: Jesse Saint <jesse(at)saintaviation.com (jesse(at)saintaviation.com)>
I know there has been discussion about this in the past, but I am wondering what conclusions were made. I am working on an RV-10 that has the James cowl and plenum and the 5" inlet rings. What was the final verdict on these? I know we haven't heard from Deems in a while. Anybody else have some info on this?
Thanks.
Jesse Saint
Saint Aviation, Inc.
jesse(at)saintaviation.com (jesse(at)saintaviation.com)
C: [url=tel:352-427-0285]352-427-0285[/url]
F: [url=tel:815-377-3694]815-377-3694[/url]
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Checked by AVG - www.avg.com
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[quote][b]
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