Sabremech Cowling Mod Testing (Ongoing)

[Guitarmaster]

Today the weather broke in the morning and I finally got to get Riley up for some preliminary testing.   Since it was starting to snow and the ceilings were coming down, the highest I could get was 5500MSL.  This didn't allow me to get up high enough to really open her up and see what she would do regarding TAS.  What I did instead was set her up like I would fly her to work, i.e. 3500 and 70% power.  
Very limited testing to day seems to indicate about a 5 knot increase in speed.  Whereas I would previously indicate 127KIAS, she now indicates 135IAS.  Four heading TAS test seems to agree.  

I also ran 25 square at 3000 and the below indication was the result.  

As it stands now, the Ram-Air gives about .7" extra.  We are thinking that changing to a smooth-flowing intake straight into the fuel servo will be good for at least .25" thereby making the Ram-Air unnecessary.  As it stands now, there are a lot of turns the air has to go through to get the fuel servo creating (i believe) some vacuum and reducing MP.  I don't know what .7" of MP translates to in HP, but it's not much.

The CHT''s are a nice, even spread, but it's too early to tell is there was any difference in temp.

Oil temps with the relocation were a solid 187.  I have no reason to believe that will change much in the warmer temps.  We shall see.

When the weather breaks, I will be able to get up higher and get some good TAS testing done.

Overall, I am super happy with the mod!

I fly (for work) over the weekend then I am on vacation the first week of January so there probably won't be much flying done until the second week.

I will be posting and changes and much better test data in the upcoming weeks.  Stay tuned! 

 

[Bob_Belville]

Sounds great! Were you seeing a full inch of MAP bump from the RAM air with the old cowl?  (Mine is 1.0-1.1 every time I check it. And I have a Challenger Air Filter which is suppose to be less restriction...)

[Guitarmaster]

Sounds great! Were you seeing a full inch of MAP bump from the RAM air with the old cowl?  (Mine is 1.0-1.1 every time I check it. And I have a Challenger Air Filter which is suppose to be less restriction...)

I would see about 1.2 with the old cowl.

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[Marauder]

I would see about 1.2 with the old cowl.

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How cold is it there? At this time of year, I think my CHTs would be in the high 200s. Does your EGT always run in the 1400s?


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[Browncbr1]

-15c on his jpi oat

[Guitarmaster]

How cold is it there? At this time of year, I think my CHTs would be in the high 200s. Does your EGT always run in the 1400s?


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I think it was 15 degrees today. If I run ROP, I am always in the 340's regardless of OAT. LOP today was 270ish.
Yes, EGT is always in the 1400s

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[Bob_Belville]

I think it was 15 degrees today. If I run ROP, I am always in the 340's regardless of OAT. LOP today was 270ish.
Yes, EGT is always in the 1400s

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FWIW, my peak EGTs are well over 1500 but I'd remind folks that is relative and the absolute value is (almost) meaningless.

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[MB65E]

Nice work Matt and Dave!!

I'm in town for Christmas in the area. It's been cold enough near Chicago that your snot freezes in your nose. Then I checked the weather at home...84° In SoCal today. :-)

Hopefully your temps can stay down and your TAS Up!

-Matt

[Guitarmaster]

***Update****

I just got back from 8000 feet and I recorded 153KTAS using a four heading method.

Thats +6 KTAS!!  

Temperature was ISA-10 and the pressure was 30.16 giving a DA of 6500.  

I suspect I should see closer to 155 on a standard day.

As a point of reference, I had the LASAR closure to begin with.

I would call the cowling mod a huge success in terms of TAS gain!

[jetdriven]

Pics or it didn’t happen.  Of the cowl that is

[carusoam]

Nice collection of details, Matt!

Best regards,

-a-

[Sabremech]

1 hour ago, jetdriven said:

Pics or it didn’t happen.  Of the cowl that is

 

[DXB]

4 hours ago, Guitarmaster said:

***Update****

I just got back from 8000 feet and I recorded 153KTAS using a four heading method.

Thats +6 KTAS!!  

Temperature was ISA-10 and the pressure was 30.16 giving a DA of 6500.  

I suspect I should see closer to 155 on a standard day.

As a point of reference, I had the LASAR closure to begin with.

I would call the cowling mod a huge success in terms of TAS gain!

Wow! Maybe the STC and install kit should include speed brakes 

It’s nice to hear about all these Fs but hoping for more some work on C’s too!! It’s the carb’d planes that need the cooling. 

[Marauder]

***Update****

 

I just got back from 8000 feet and I recorded 153KTAS using a four heading method.

 

Thats +6 KTAS!!  

 

Temperature was ISA-10 and the pressure was 30.16 giving a DA of 6500.  

I suspect I should see closer to 155 on a standard day.

As a point of reference, I had the LASAR closure to begin with.

 

I would call the cowling mod a huge success in terms of TAS gain!

 

Matt - just finished flying a similar profile per our discussion. I went up to 8500, ran full throttle, 2500RPM and 80° ROP.

 

I am really curious on your before CHTs. Looks like the oil relocation should be okay.

 

Here are my numbers:

 

153 KTAS at 8,500 or 6,200 DA, at 80° ROP

 

 

70° HP, CHTs are in the 260 to 290° range. Climb saw them in the 330° range on the peaked cylinder.

 

 

The fancy GTN calculator:

 

Sorry for the bumpy photo, the calculated DA, winds, etc.

 

 

 

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[N601RX]

Looks good!  Has anyone flew any of the engine cooling certification profiles yet?  Load to max weight, climb to 10k at Vy and then correct for temp to verify engine and oil cooling? 

Edited December 29, 2017 by N601RX

[Guitarmaster]

31 minutes ago, Marauder said:

 

Matt - just finished flying a similar profile per our discussion. I went up to 8500, ran full throttle, 2500RPM and 80° ROP.

I am really curious on your before CHTs. Looks like the oil relocation should be okay.

Here are my numbers:

153 KTAS at 8,500 or 6,200 DA



70° HP, CHTs are in the 260 to 290° range. Climb saw them in the 330° range on the peaked cylinder.



The fancy GTN calculator:


Sorry for the bumpy photo, the calculated DA, winds, etc.




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Thanks for posting Chris.  It looks like the third cowl flap or something to draw a more negative pressure in the bottom part of the cowl may be of benefit.

[bonal]

6 hours ago, Guitarmaster said:

***Update****

I just got back from 8000 feet and I recorded 153KTAS using a four heading method.

Thats +6 KTAS!!  

Temperature was ISA-10 and the pressure was 30.16 giving a DA of 6500.  

I suspect I should see closer to 155 on a standard day.

As a point of reference, I had the LASAR closure to begin with.

I would call the cowling mod a huge success in terms of TAS gain!

Great to see it all come together. Wondering what your throttle set MP and RPM were to see 153Ktas. I know with my C 2 on board at 8000ft  3 and 4 heading method we got 148 and 149ktas respectively and I know others that have numbers similar to that with their C models. I would expect you would be faster. Admittedly we were pushing for best speed at wot 2600rpm.

[Guitarmaster]

Since MS deleted half my post, I will redo it here....

Attached are two flight with similar weather conditions roughly a year apart.

 

This is the old cowl.

This is the new

We are going to have some cooling to perfect.  To be fair, we kind of thought this was going to be the case since we removed the third cowl flap.  This will be an easy change.  David is also working on some other ideas to improve the exit air flow.  

Opinions and results thus far:

1) I have a solid 153 KTAS.  That's up 6 knots.  

2)  Jury is out on the oil cooler relocation.  It seems a slight bit warmer than before, but I believe that will change with an exit-air change.  It does look better though.

3)  The Ram-Air is going to be taken off the airplane.  At .7" it just isn't worth keeping.  In addition, with the Ram-air gone, there will be a smooth flow from the filter directly into the fuel servo.  That will eliminate the present 90 degree bend the air has to take.  I am hoping that will be good for .5".  

4)  I have a working theory that since the temps are warmer, there is not enough exit air and air is packing up on the top side creating some cooling drag.  Maybe with a higher negative pressure on the bottom of the cowl, the plane will be faster yet     

5) Finally, David @Sabremech has been great to work with!  When I started this project, we knew this was a "semi-experimental" thing with the injected models.  I was happy to be the guinea pig as I love experimenting.   I can't wait to get the ram-air removed and continue helping in any way I can to make his design perfect.   

 

 

 

Edited December 30, 2017 by Guitarmaster

[Guitarmaster]

7 minutes ago, bonal said:

Great to see it all come together. Wondering what your throttle set MP and RPM were to see 153Ktas. I know with my C 2 on board at 8000ft  3 and 4 heading method we got 148 and 149ktas respectively and I know others that have numbers similar to that with their C models. I would expect you would be faster. Admittedly we were pushing for best speed at wot 2600rpm.

WOT, 2500, 72% power.

[Guitarmaster]

3 hours ago, bonal said:

Great to see it all come together. Wondering what your throttle set MP and RPM were to see 153Ktas. I know with my C 2 on board at 8000ft  3 and 4 heading method we got 148 and 149ktas respectively and I know others that have numbers similar to that with their C models. I would expect you would be faster. Admittedly we were pushing for best speed at wot 2600rpm.

David's "C" is faster than my "F".  To be fair, the "F" is somewhat bigger, but I do have 20 more HP.   After flying his "C", my plane feels like a heavy.   He has all the speed mods on his including the sloped windshield.  I don't have that.  I only have the brake caliper rotation and David's cowl mod.

I have noticed his plane is slipperier than mine.  

 

[jamesm]

So I am I reading your charts correctly ??? You have higher CHT's  with the mod?  I am interested in  takeoff ?

Thanks,

James

[Marauder]

So I am I reading your charts correctly ??? You have higher CHT's  with the mod?  I am interested in  takeoff ?
Thanks,
James

That is the way I read it as well. Matt’s F and mine are 7 serial numbers apart. We both have/had the Lasar cowl mod and a fixed third cowl flap in the center of the cowling. The temps I posted are fairly typical for a really cold day. In temps from freezing to the 90s, my CHTs will run in the low 300s to the mid 300s. His first JPI data set is what I normally would expect at temps near freezing or slightly above.

Matt’s F had the third fixed cowl flap removed and we suspect this may be what is leading to the higher temps. I think he and David have plans on doing further experimentation.


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[jamesm]

Wouldn't that suggest that exit area needs to be larger ? 

A while back I posted a video Pipistrel Panthera,  where they discussed about engine cooling exit area being larger than air inlets and exiting the air on side  of the cowl rather than the bottom since that is high pressure area .  Maybe the it isn't as high pressure on a Mooney but I have noticed that some  Bonanza engine  cowling have side louvers   and wonder if that  isn't the case on the Bonanza's as well is to exit into a lower pressure area.

 

James '67C

[Hank]

2 minutes ago, jamesm said:

I have noticed that some  Bonanza engine  cowling have side louvers . . .

So did cars back in the day when Bos were first drawn up . . .

[jetdriven]

Newer planes have very small inlet area and large exit area. Like a 1:2.5 ratio. Look at the ovation, very small inlet area and large fixed exit area. My J spills air out the front when the cowl flaps are closed, why else would a leaking engine pull air and oil  forward And onto the windshield.