"SabreCowl" Update

[Guitarmaster]

Those that have followed the progress of this mod know that I have experienced a 4-6 KT gain in TAS (depending on altitude and weight of course.)  Also, there appears to be a "ram-air" effect since the intake is in the left nostril.  Near as I can tell, it seems to be roughly equivalent to what I saw with the "Ram Air" open in flight.  With a DA of 9900ft, I was seeing 22"MP   Unfortunately, along with the increased speed, we also experienced an increase in CHT numbers to what I would consider unacceptable (390-400). 

There has been a period of silence on the progress as we were working the CHT problem.  During this time, we came up with the idea to install side vents in the cheek cowls.  Today David got the side vents installed.  The position of the vents was determined with the "oil test " where I smeared oil on the airplane and went flying.  We then determined where the high-speed air (thin oil streaks) was and installed the vents in the low pressure air.  This is not unlike the Cessna 180 STC for cooling.

I am happy to report I experienced a 20 degree drop in CHT while running 100 degrees leaner on the test flight today.  This was done with roughly the same atmospheric conditions. Previously, I would have to operate 200 ROP to achieve <400 degrees CHT.   I am now running ~375 Degrees in cruise 100 ROP, and below 400 in a hard climb.  It was 85 degrees OAT today.  Not only have the temps decreased, but it looks cool too!  #winning  

Although the CHT's are what I would consider acceptable, we want to see 360 or less in cruise.  David is now looking at opening the inlets a bit to create some more pressure in the top of the cowl.

It's been a long project, but it is coming to a close soon.  I have gained speed, aesthetics and a great friend @Sabremech through this!!  

[Andy95W]

I think we may be looking at a potential mod for all vintage Mooneys, not just the ones with Dave's new cowling.

Very nice work.

[MB65E]

That’s where I always thought the oil cooler exit should be! Nice! 

-Matt

[carusoam]

Fantastic wind-tunnel details, Matt!

Great results as well.

Great efforts with and by David.

Thanks for sharing.

Keep in mind, I first though you sprung an oil leak...   

I feel much better now...

Best regards,

-a-

[Bob_Belville]

Matt, what about oil temp? Was that an issue as well? Did it improve.

I finally have my plane flying after 3 months in the paint shop. My CHTs  are acceptable but Oil Temp is high. I don't think it is due to the new cowl but I wonder what you're seeing.

I made to flights yesterday, MRN-TTA and back. Very hot OAT.

On the first of the flights yesterday CHTs averaged 334/334/343/316, max were 372/368/379/344. OilT avg: 215, max 236.  

On the second flight in the heat of the afternoon CHT averaged: 341,340,352,323 and max 378,376,389,357. OilT was 227 avg, 242 max. (OAT was 37 max.) 

 

This was at 65% power or less during cruise and with cowl flaps open. The avg and max temps though include long hot climbs.  

[Guitarmaster]

15 minutes ago, Bob_Belville said:

Matt, what about oil temp? Was that an issue as well? Did it improve.

I finally have my plane flying after 3 months in the paint shop. My CHTs  are acceptable but Oil Temp is high. I don't think it is due to the new cowl but I wonder what you're seeing.

I made to flights yesterday, MRN-TTA and back. Very hot OAT.

On the first of the flights yesterday CHTs averaged 334/334/343/316, max were 372/368/379/344. OilT avg: 215, max 236.  

On the second flight in the heat of the afternoon CHT averaged: 341,340,352,323 and max 378,376,389,357. OilT was 227 avg, 242 max. (OAT was 37 max.) 

 

This was at 65% power or less during cruise and with cowl flaps open. The avg and max temps though include long hot climbs.  

Today I saw 205 on the oil temp.  Before the vents, I was seeing 215 in the hot weather routinely, and one, long, hard climb yielded 240, but decreased to about 215 in cruise.  I would say I dropped 10 degrees on the oil temp.
Admittedly, I don't think the oil cooler relocation is all it's cracked up to be.  To wit, I think oil temp would have been the same without the cowl mod and with the relocation.

Edited July 2, 2018 by Guitarmaster

[Bob_Belville]

2 minutes ago, Guitarmaster said:

Today I saw 205 on the oil temp.  Before the vents, I was seeing 215 in the hot weather routinely, and one, long, hard climb yielded 240, but decreased to about 215 in cruise.  I would say I dropped 10 degrees on the oil temp.
Admittedly, I don't think the oil cooler relocation is all it's cracked up to be.  To wit, I think oil temp would have been the same without the cowl mod and the relocation.

I worked on my baffling today. The lower baffle under the 2 & 4 cylinders was not snug. I hope that closing that up will push more air through the cooler. And I am suspicious that the vernatherm may be bad.  

[KSMooniac]

Nice work so far! Was there any speed bit after adding the new exhaust vents?

FWIW the LoPresti cowl has a similar feature, and the M20 Turbos STC adds some louvers there as well. Surely in both cases there was a need! It is always reassuring when doing an analysis out e development program that you get to a result that is supported with prior work.

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[NJMac]

Nice!  

[mike_elliott]

Nice! I am just wondering if the cowl flaps would be needed at all now! Maybe a NACA duct design and flush rivets for ver 1.2 David!

 

[Sabremech]

5 minutes ago, mike_elliott said:

Nice! I am just wondering if the cowl flaps would be needed at all now! Maybe a NACA duct design and flush rivets for ver 1.2 David!

 

Good morning Mike, exactly what we’ve been thinking. More thoughts and ideas for SabreCowl Gen2. I would have used flush rivets but the first set of cheek vents didn’t have a thick enough flange to allow for me to countersink the rivets. The vents going forward will be flush riveted  and molded in the sides of the cowling on Gen2.

Thanks,

David

 

[Bob_Belville]

1 minute ago, Sabremech said:

Good morning Mike, exactly what we’ve been thinking. More thoughts and ideas for SabreCowl Gen2. I would have used flush rivets but the first set of cheek vents didn’t have a thick enough flange to allow for me to countersink the rivets. The vents going forward will be flush riveted  and molded in the sides of the cowling on Gen2.

Thanks,

David

 

David, I guess the vent is below the cowl support rod which is pretty close to the inside of the cheek. 

Glad I had Joe provide me with some of all my paint colors. 

[Sabremech]

18 minutes ago, Bob_Belville said:

David, I guess the vent is below the cowl support rod which is pretty close to the inside of the cheek. 

Glad I had Joe provide me with some of all my paint colors. 

Good morning Bob, that cowl support rod will cause me some grief as it is right where the cheek vent goes. I’ll work that issue out when I fit the cheek vents on mine. I wasn’t sure if you had the cowl rod or not. 

[Bob_Belville]

1 minute ago, Sabremech said:

Good morning Bob, that cowl support rod will cause me some grief as it is right where the cheek vent goes. I’ll work that issue out when I fit the cheek vents on mine. I wasn’t sure if you had the cowl rod or not. 

I'm headed to MRN this morning. I also need to examine the right side where I have SCAT heater line that in that vent area. I think it can be routed around a new vent.

David, I tightened the outer baffle under cyls 2/4 yesterday. I think we had inadvertently swapped the rods left and right when we installed the new cowl just before the plane went to Hawk. The rod under 2&4 was not threaded enough to pull the baffle up tight. I removed it and ran a 10-32 die down another 2 inches. Reinstalled and now snug. I can imagine that a lot of air from above #4 "escaped" though the loose baffle that should have been going through the cooler. (I'll have Lynn check out my work but I wonder what you think about how tight to tighten that rod? What would happen if the baffle was too tight? Tear flange at rod hole...? I don't suppose the cyl would care but maybe?)

[Raptor05121]

This. Is. Amazing.

[Marauder]

Those that have followed the progress of this mod know that I have experienced a 4-6 KT gain in TAS (depending on altitude and weight of course.)  Also, there appears to be a "ram-air" effect since the intake is in the left nostril.  Near as I can tell, it seems to be roughly equivalent to what I saw with the "Ram Air" open in flight.  With a DA of 9900ft, I was seeing 22"MP   Unfortunately, along with the increased speed, we also experienced an increase in CHT numbers to what I would consider unacceptable (390-400). 
There has been a period of silence on the progress as we were working the CHT problem.  During this time, we came up with the idea to install side vents in the cheek cowls.  Today David got the side vents installed.  The position of the vents was determined with the "oil test " where I smeared oil on the airplane and went flying.  We then determined where the high-speed air (thin oil streaks) was and installed the vents in the low pressure air.  This is not unlike the Cessna 180 STC for cooling.


I am happy to report I experienced a 20 degree drop in CHT while running 100 degrees leaner on the test flight today.  This was done with roughly the same atmospheric conditions. Previously, I would have to operate 200 ROP to achieve Although the CHT's are what I would consider acceptable, we want to see 360 or less in cruise.  David is now looking at opening the inlets a bit to create some more pressure in the top of the cowl.
It's been a long project, but it is coming to a close soon.  I have gained speed, aesthetics and a great friend

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I still wonder how much effect the size the cowl openings have. Granted, the Acclaim has a few more ponies under the hood, the size of the cowl openings are pretty impressive.







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[KSMooniac]

More cylinders to cool, intercoolers, thinner air at attitude all contribute to larger inlets on the Acclaim.

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[HRM]

1 hour ago, Marauder said:

It's been a long project, but it is coming to a close soon.  I have gained speed, aesthetics and a great friend

The aesthetics are through the roof, just modernizes the bird in a great way.

[Sabremech]

2 hours ago, Marauder said:

 

I still wonder how much effect the size the cowl openings have. Granted, the Acclaim has a few more ponies under the hood, the size of the cowl openings are pretty impressive.







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Hi Marauder,

My inlets are from the James Aircraft Holy Cowl and are interestingly the same size as the LoPresti cowling. I think now that they may be too small to work on all the models of Mooney’s and each engine being different in performance and health. I will be increasing them and try a larger size on Matt’s and mine to see the results. I think that will get Matt’s temps down as well as mine. I might give up a little speed but not much. 

David

[Bob_Belville]

6 hours ago, Sabremech said:

Good morning Bob, that cowl support rod will cause me some grief as it is right where the cheek vent goes. I’ll work that issue out when I fit the cheek vents on mine. I wasn’t sure if you had the cowl rod or not. 

David, pics of the cowl support rods. If you stay below the rod you'll be into the curvature. Maybe we won't have to go there. In addition to work on baffles and seals, I ordered a new vernatherm this morning. Studying the history of the data across time for my OilT leads me to suspect there's something going on besides airflow. 

[DXB]

I need cowl cheek vents.  Long live Sabremech.

[MyNameIsNobody]

Coming along.  Thanks for the update!  

[SOSTED]

Do you have any performance increase from the cowl mod

[MyNameIsNobody]

11 hours ago, SOSTED said:

Do you have any performance increase from the cowl mod

Literally said in first sentence a 4-6 knot speed increase with cowl...

[Mooneymuscle56m]

Another thing to consider on the larger opening in the acclaim. 

The acclaim has nothing attached to the cowl.  The two intercoolers along side of cylinders, huge oil cooler, Intake is behind the spinner, no cowl flaps.  

Mechanics I’ve spoken with prefer to work on an acclaim, I guess the bravo has a lot attached to the cowling.