Do you lean as you climb ?

[A64Pilot]

C-182 will out climb my aircraft at least in angle. I can’t climb with them, but I don’t climb at max angle speed either, or max rate for that matter. 

Bonanza isn’t 200 HP but will leave me in a climb as will a Viking that leaves the Bo, even a 180 HP 172 does or a C-180, lots of others, I might could climb at his angle but I won’t due to engine temps, I’m no where near the red of course but I won’t push it there, some routinely do push redlines but other than RPM I won’t.

This is sort of like the argument of you can get into a field you can’t get out of, quoting distance to break ground as “proof” but the battle isn’t over in most tight fields when you break ground, it begins then, it’s over when you clear the tall trees at the end of the runway.

4 cyl Mooney’s aren’t stellar climbers, but that’s OK, they are likely the fastest 4 cyl Certified four seat airplane and quite possibly capable of the most ground covered for the least amount of fuel.

I can only image the 300 HP Mooney’s are likely stellar climbers, it’s a HP thing.

Same thing about arguing that a Mooney isn’t more cramped than a Bo or C-182 etc by pointing to some measurement, he’ll just sit in a C-182 and try to honestly say it not roomier, but that too is OK, because even with its higher HP and fuel burn, it’s slower.

I have to leave now for a VA appt in my Miata, guess what, it’s more cramped than a Suburban, but that is OK because it’s a lot more fun to drive.

[EricJ]

1 hour ago, DCarlton said:

I haven't looked in years, but is there a normally aspirated four cylinder piston powered certified aircraft that has better climb performance than a M20?  Will have to go search now.  

Some may climb better initially but the long Mooney wing seems like it can sustain it better through higher altitudes.   RVs climb like crazy initially but seem to slow down as they go more than a Mooney does.

[Shadrach]

2 hours ago, A64Pilot said:

C-182 will out climb my aircraft at least in angle. I can’t climb with them, but I don’t climb at max angle speed either, or max rate for that matter. 

Bonanza isn’t 200 HP but will leave me in a climb as will a Viking that leaves the Bo, even a 180 HP 172 does or a C-180, lots of others, I might could climb at his angle but I won’t due to engine temps, I’m no where near the red of course but I won’t push it there, some routinely do push redlines but other than RPM I won’t.

This is sort of like the argument of you can get into a field you can’t get out of, quoting distance to break ground as “proof” but the battle isn’t over in most tight fields when you break ground, it begins then, it’s over when you clear the tall trees at the end of the runway.

4 cyl Mooney’s aren’t stellar climbers, but that’s OK, they are likely the fastest 4 cyl Certified four seat airplane and quite possibly capable of the most ground covered for the least amount of fuel.

I can only image the 300 HP Mooney’s are likely stellar climbers, it’s a HP thing.

Same thing about arguing that a Mooney isn’t more cramped than a Bo or C-182 etc by pointing to some measurement, he’ll just sit in a C-182 and try to honestly say it not roomier, but that too is OK, because even with its higher HP and fuel burn, it’s slower.

I have to leave now for a VA appt in my Miata, guess what, it’s more cramped than a Suburban, but that is OK because it’s a lot more fun to drive.

If a 180hp C172 will out climb your airplane than something odd is going on with the loading comparison, or there is a problem with your plane. I have lots of time in 172s  I don’t think any of them will out climb my plane to 10k including the XP. In response to your claims, I posted the closest thing I could to verifiable, 3rd party data showing a climb from 700’ to 10000’ in 8mins 12 seconds for an average of >1100fps. Crickets.  Maybe it’s just that the Mooneys you’ve flown are tubby in the weight department. Perhaps there are other factors. But your assertion that they don’t climb well is not founded in actual numbers. Pound for pound they are top of class climbers and more useable above 8k than most other 200hp birds.  

I did my high performance checkout in a P-ponk C180K. It did not feel high performance at all coming from the little 200hp Mooney I flew right before the checkout.

[A64Pilot]

5 hours ago, EricJ said:

Some may climb better initially but the long Mooney wing seems like it can sustain it better through higher altitudes.   RVs climb like crazy initially but seem to slow down as they go more than a Mooney does.

I can believe that, I took the first post to mean initial rate as in low altitude climb.

The RV’s are little airplanes with big motors, so of course they climb quickly, but that short thick wing is actually a high drag wing they get their speed from brute force not low drag, I imagine they aren’t stellar gliders.

Mooney does do better at higher altitudes than down low, to me they just aren’t stellar climbers, I think due to their relatively low HP per size / weight of aircraft. It is only a 200 HP airplane, but then my Maule was only 235 and I don’t think many are going to try to claim a 4 cyl Mooney can climb with an M-6 235 Maule, but at high altitude it just might.

Maule’s wing isn’t nearly as efficient by a long shot.

Surprisingly the Mooney wing looks long but really isn’t longer than many. All 100 series Cessna’s from the lowly 172 and on have 36’ wings I believe, so real close to ours. The Bo has relatively short wings at 33’ , but has more wing area, even the 172 has more wing area than a Mooney, not by a whole lot

[DCarlton]

I honestly feel like I’ve out climbed and outrun every high wing Cessna I’ve ever take off behind.  In fact I’m usually concerned about overtaking them safely.  

[0TreeLemur]

17 minutes ago, DCarlton said:

I honestly feel like I’ve out climbed and outrun every high wing Cessna I’ve ever take off behind.  In fact I’m usually concerned about overtaking them safely.  

A hangar mate flew me in January to pick up my J after its annual in his 180 hp Skyhawk XP.   It had been four or more years since I had ridden in one of those.  On a cold day, it climbed like crazy, but was doing so at 75 knots.   The Mooney requires us to keep up the speed to cool the engine.  I never climb at less than 100 knots after I clear any obstacles.  If I do- it's almost always because I went into "Gee I'm flying in a plane!" passenger mode and forgot to raise the gear...

[Shadrach]

7 hours ago, 0TreeLemur said:

A hangar mate flew me in January to pick up my J after its annual in his 180 hp Skyhawk XP.   It had been four or more years since I had ridden in one of those.  On a cold day, it climbed like crazy, but was doing so at 75 knots.   The Mooney requires us to keep up the speed to cool the engine.  I never climb at less than 100 knots after I clear any obstacles.  If I do- it's almost always because I went into "Gee I'm flying in a plane!" passenger mode and forgot to raise the gear...

book climb numbers for a J vs an XP at MGW favor the J by almost 200fpm. If an XP feels like a stronger climber on the same day it’s likely perception rather than reality unless something is wrong.

[M20F]

I just push the turbo in more, leaning is for posers.  

[A64Pilot]

9 hours ago, 0TreeLemur said:

A hangar mate flew me in January to pick up my J after its annual in his 180 hp Skyhawk XP.   It had been four or more years since I had ridden in one of those.  On a cold day, it climbed like crazy, but was doing so at 75 knots.   The Mooney requires us to keep up the speed to cool the engine.  I never climb at less than 100 knots after I clear any obstacles.  If I do- it's almost always because I went into "Gee I'm flying in a plane!" passenger mode and forgot to raise the gear...

Bingo, that’s it. A Mooney may be climbing at as high or even a higher rate, but it’s going faster so it’s gradient is lower.

The neighbor in his 180 HP 172 which is an older one that that H2AD motor I think and got converted to 180 HP will take off right before me, I’ll catch and pass him of course but he’s at a higher altitude when I do. I go by under him, a Bonanza or Viking goes by above him, the Viking above the Bo likely I suspect because it has 300 HP, but then they have at least 85 to 100 more HP than me too, but neither is much if any faster at cruise, but burn roughly 1/3 more fuel. I think actually I’m faster than the Viking, if so it’s not by much though, the Bo is faster than I am, but again not by much though.

Say for example your told to cross X fix at or above a certain altitude, an airplane climbing at 1,000 FPM at 80 MPH will easily make that but another climbing at 1,000 FPM at 100 MPH may not.

Cooling is the other issue, it seems other aircraft just don’t require as much speed to keep engine temps down, I suspect that’s simply Drag reduction of the Mooney, maybe the older Mooney’s don’t but it seems my J likes higher speeds to keep temps down. Higher speeds reduce both rate and gradient of course. There is a surprising amount of drag in engine cooling, you can find varying numbers on the internet but it’s one of the best places that big drag reduction can be had, I suspect some of the J’s drag reduction came from improved engine cooling air flow management.

Don’t get me wrong it does really well for a four cylinder airplane, but then most four passenger four cylinder airplane’s aren’t strong climbers. Climb performance is a function of excess HP and when you only have 180 to 200 horses and your a moderately fast airplane there just isn’t a lot of excess.

[DCarlton]

1 hour ago, A64Pilot said:

Bingo, that’s it. A Mooney may be climbing at as high or even a higher rate, but it’s going faster so it’s gradient is lower.

The neighbor in his 180 HP 172 which is an older one that that H2AD motor I think and got converted to 180 HP will take off right before me, I’ll catch and pass him of course but he’s at a higher altitude when I do. I go by under him, a Bonanza or Viking goes by above him, the Viking above the Bo likely I suspect because it has 300 HP, but then they have at least 85 to 100 more HP than me too, but neither is much if any faster at cruise, but burn roughly 1/3 more fuel. I think actually I’m faster than the Viking, if so it’s not by much though, the Bo is faster than I am, but again not by much though.

Say for example your told to cross X fix at or above a certain altitude, an airplane climbing at 1,000 FPM at 80 MPH will easily make that but another climbing at 1,000 FPM at 100 MPH may not.

Cooling is the other issue, it seems other aircraft just don’t require as much speed to keep engine temps down, I suspect that’s simply Drag reduction of the Mooney, maybe the older Mooney’s don’t but it seems my J likes higher speeds to keep temps down. Higher speeds reduce both rate and gradient of course. There is a surprising amount of drag in engine cooling, you can find varying numbers on the internet but it’s one of the best places that big drag reduction can be had, I suspect some of the J’s drag reduction came from improved engine cooling air flow management.

Don’t get me wrong it does really well for a four cylinder airplane, but then most four passenger four cylinder airplane’s aren’t strong climbers. Climb performance is a function of excess HP and when you only have 180 to 200 horses and your a moderately fast airplane there just isn’t a lot of excess.

I had trouble keeping my temps down before my engine overhaul.  After the overhaul, I hardly ever think about it; it stays green.  I usually climb at 120 mph though and never below 104.  Mine has a fixed center cowl flap; installed years ago when I was flying in the summer in the desert often.  Temps aren't an issue.  

[A64Pilot]

I would assume during overhaul you got new baffling.

By fixed center cowl flap are you talking about a modification? Cooling “lips” are very common on float planes because of course they are working harder at slower airspeed than wheeled aircraft and run hotter just like banner tow aircraft do.

Here is a picture of one installed on a C-140 for example, I don’t know if it was ever on floats or the owner is just looking for additional cooling.

 

[Shadrach]

3 hours ago, DCarlton said:

I had trouble keeping my temps down before my engine overhaul.  After the overhaul, I hardly ever think about it; it stays green.  I usually climb at 120 mph though and never below 104.  Mine has a fixed center cowl flap; installed years ago when I was flying in the summer in the desert often.  Temps aren't an issue.  

Perhaps the reason my climb numbers seem skewed compared to others is the guppy mouth cowl intake. While less than attractive, I really don’t have to think about CHTs much except for in the hottest part of the summer or in winter when I try to keep them from falling much below 300°. This means I can climb at almost any angle I want within reason. It would be a rare set of circumstances where any 172 is able to  outclimb me in angle or rate. Our main runway is 7000’ long and at mid weight it’s not a huge challenge to be at pattern altitude before reaching the end. An E model will do even better.

A few years ago I remember a thread where everyone was talking about how badly Mooney‘s climb in the landing configuration (Full flaps and gear down).  I decided to test to see if this was true.  What I found was that the airplane climbed just fine with full flaps in the gear down (1000fpm) but I had to be willing to fly at ~80MIAS. The deck angle was very shallow. It was sort of like being in an elevator.

[DCarlton]

3 hours ago, A64Pilot said:

I would assume during overhaul you got new baffling.

By fixed center cowl flap are you talking about a modification? Cooling “lips” are very common on float planes because of course they are working harder at slower airspeed than wheeled aircraft and run hotter just like banner tow aircraft do.

Here is a picture of one installed on a C-140 for example, I don’t know if it was ever on floats or the owner is just looking for additional cooling.

 

Yeah it was a Mooney mod offered years ago.  I've seen one other aircraft on Mooneyspace with the same fixed center opening.  I'll have to make a good pic and post it.  

[Hank]

3 hours ago, Shadrach said:

Perhaps the reason my climb numbers seem skewed compared to others is the guppy mouth cowl intake. While less than attractive, I really don’t have to think about CHTs much except for in the hottest part of the summer or in winter when I try to keep them from falling much below 300°.

I remember reading that air flow reversed and came out the front of the big guppy mouth. Modern fluid dynamics resulted in the guppy mouth closure that so many of us have on our vintage Mooneys. 

This is the guppy mouth closure, which yields cooler engines:

[Shadrach]

1 hour ago, Hank said:

I remember reading that air flow reversed and came out the front of the big guppy mouth. Modern fluid dynamics resulted in the guppy mouth closure that so many of us have on our vintage Mooneys. 

This is the guppy mouth closure, which yields cooler engines:

So I’ve been told. Regardless of theory, in reality my bird runs very cool.

[PeteMc]

2 hours ago, Hank said:

I remember reading that air flow reversed and came out the front of the big guppy mouth.

I remember a discussion how adjusting the cowl flaps so that they did not close completely helped a lot with bleeding off that reverse pressure.  And once that pressure is removed, you may pick up a knot or two! 

 

[A64Pilot]

16 hours ago, Shadrach said:

So I’ve been told. Regardless of theory, in reality my bird runs very cool.

My fixed wing test pilot mentor told me that up to 25% of the total drag on the average piston GA airplane is from cooling drag, Ralph I’m sure was speaking about vintage aircraft, but 25% is a big number.

Internet will return lower numbers but I know Ralph knows what he’s talking about.

Significant drag reductions from cooling drag have been made in modern designs, but I believe also at the expense of cooling margins. Even with turbines during Certification we have to do cooling climbs which are worst case of course and are corrected for temps, it’s best for passing the test to test in as hot a weather that you can because the corrections are conservative.

The max allowable temps come from the component manufacturers of course, and the max cyl head temps are well in excess I believe of what most of us are comfortable with, so I think it’s common for newer designs to have to climb at higher air speeds than older designs in order to keep temps where some of us are comfortable with.

If I’m traveling and have no restrictions on altitude I’ll often climb at the fastest airspeed that will give me 500 FPM, that accomplishes two things, first my speed is much faster of course and the point when traveling is to get there, but it also keeps my cyl head temp very close to cruise numbers. Being as I’m down in the flat lands I don’t go very high usually, it’s rare for me to get above 10K. I’ll only go up there for cloud clearances or to get a smooth ride.

Lately I’ve come to rethink that because you burn significant fuel climbing, so it’s likely that for fuel consumption it’s best to minimize time spent climbing, everything is a compromise

If I had to climb over rocks like guys out West do, well then that’s different of course, I’ve had to circle as I’m sure everyone has to get enough altitude to clear terrain at a comfortable altitude, so a slow climb isn’t productive.

 

[Shadrach]

On 2/16/2024 at 12:22 PM, A64Pilot said:

My fixed wing test pilot mentor told me that up to 25% of the total drag on the average piston GA airplane is from cooling drag, Ralph I’m sure was speaking about vintage aircraft, but 25% is a big number.

Internet will return lower numbers but I know Ralph knows what he’s talking about.

Significant drag reductions from cooling drag have been made in modern designs, but I believe also at the expense of cooling margins. Even with turbines during Certification we have to do cooling climbs which are worst case of course and are corrected for temps, it’s best for passing the test to test in as hot a weather that you can because the corrections are conservative.

The max allowable temps come from the component manufacturers of course, and the max cyl head temps are well in excess I believe of what most of us are comfortable with, so I think it’s common for newer designs to have to climb at higher air speeds than older designs in order to keep temps where some of us are comfortable with.

If I’m traveling and have no restrictions on altitude I’ll often climb at the fastest airspeed that will give me 500 FPM, that accomplishes two things, first my speed is much faster of course and the point when traveling is to get there, but it also keeps my cyl head temp very close to cruise numbers. Being as I’m down in the flat lands I don’t go very high usually, it’s rare for me to get above 10K. I’ll only go up there for cloud clearances or to get a smooth ride.

Lately I’ve come to rethink that because you burn significant fuel climbing, so it’s likely that for fuel consumption it’s best to minimize time spent climbing, everything is a compromise

If I had to climb over rocks like guys out West do, well then that’s different of course, I’ve had to circle as I’m sure everyone has to get enough altitude to clear terrain at a comfortable altitude, so a slow climb isn’t productive.

 

I’ve been told that the J cowl is superior  in terms of drag and cooling efficiency. I believe that both of those statements are true. However, efficiency equals better cooling per volume of air, it doesn’t necessarily mean better cooling in general. Speaking hypothetically, if the old guppy mouth ingests 400% more air but is only 50% as efficient, it still offers more cooling capacity. This may be especially relevant during low speed and high angle of attack operations. 
it would be good to hear from anyone that has significant time in both vintage and modern Mooneys or has gone from a vintage guppy mouth to an updated J style cowl. 
I have some J time but certainly not enough to make a meaningful comparison. I can only say that cooling is not much of a concern with a stock vintage cowl…save for maybe a sustained climb at Vx on a hot summer day.

[A64Pilot]

Ref the airflow reversing and flowing out of the engine inlet, Uh, that’s not going to happen I don’t think, if there was no exit there would be no airflow, open just a little exit the flow is slow, but it’s still flowing, but it’s not going blow air out of the inlet.

Only way I can see to make the air flow out of the front is if the pressure inside of the cowl were higher than the ram air from the front

Now I can see how air could flow in reverse through an oil cooler as it’s possible that the pressure in the cowl could be higher than in front of the cooler due to its mounting angle, maybe, but a direct ram like the inlet? I don’t think that’s likely.

It would be real easy to tuft the inlet and prove or disprove it.

 

[Hank]

13 hours ago, A64Pilot said:

Ref the airflow reversing and flowing out of the engine inlet, Uh, that’s not going to happen . . .

It would be real easy to tuft the inlet and prove or disprove it.

That was done during development of the guppy mouth closure. Some air goes in, some comes out.

The inlet needs to be matched to the outlet, not so much by area but by flow rate; going through the engine slows the air down, and the cowl flap exit area is a fraction the size of the guppy mouth, so the air that comes in can't all exit through the flaps and must go somewhere, which is back out the front. 

The inlet needs to be smaller than the exit, to account for the air slowing down as it goes through cylinder fins and is pushed down to the cowl flaps. The guppy mouth is huge . . . .

[N201MKTurbo]

Remember that air flows because of pressure. When the pressure in the upper cowl exceeds the dynamic pressure in front of the cowl, no more air will flow into the cowl, it will just go around it. 

The flow through the cylinders is determined by the pressure differential above and below the cylinders. The pressure in the lower cowl is determined by the cowl flap opening size and the pressure outside the cowl flaps. the pressure outside the cowl flaps can be lower than ambient. 

I believe the pressure in the upper cowl is determined by airspeed, just like a pilot tube. That pressure decreases as air flows through the cylinders. As the opening gets smaller, it produced less drag, but it also creates a bigger restriction to air flow. So, everything is a compromise. 

The other concern is the amount of drag of the cooling air moving through the upper cowl. The early cowls did nothing in that regard. The J cowl has internal features to smooth the airflow inside the cowl.

[Shadrach]

28 minutes ago, N201MKTurbo said:

Remember that air flows because of pressure. When the pressure in the upper cowl exceeds the dynamic pressure in front of the cowl, no more air will flow into the cowl, it will just go around it. 

The flow through the cylinders is determined by the pressure differential above and below the cylinders. The pressure in the lower cowl is determined by the cowl flap opening size and the pressure outside the cowl flaps. the pressure outside the cowl flaps can be lower than ambient. 

I believe the pressure in the upper cowl is determined by airspeed, just like a pilot tube. That pressure decreases as air flows through the cylinders. As the opening gets smaller, it produced less drag, but it also creates a bigger restriction to air flow. So, everything is a compromise. 

The other concern is the amount of drag of the cooling air moving through the upper cowl. The early cowls did nothing in that regard. The J cowl has internal features to smooth the airflow inside the cowl.

So which ran hotter? Your F or your J?

[47U]

52 minutes ago, N201MKTurbo said:

Remember that air flows because of pressure. When the pressure in the upper cowl exceeds the dynamic pressure in front of the cowl, no more air will flow into the cowl, it will just go around it.

How much does air flowing through the cylinder fins heat the air therefore expanding the volume?  

Is there a (significant?) change in pressure in the upper cowl depending on where the heat muff cold air inlet is located?  Early C’s tap this air from behind #3 cylinder.  Later C’s take the air from in front of #2 cylinder.  My friend has a G, the heat muff air is tapped from the lower deck, below the cylinders, in front of #2.  Were these changes made only to improve the organization of the ducting to support carb and cabin heat?

Later C’s had fixed cowl flaps.  Then I saw a later C on the ramp and it had a small set of louvers in both cheek cowls.  Obviously, to improve airflow out of the lower deck.  If the oil cooler outlet was ducted to a similar louver in the cheek cowl, would oil cooler effectiveness and overall better airflow out of the lower deck resulting in lower CHTs? 

What about the oil cooler?  I’ve read that it’s possible to have reverse airflow from the lower deck out the front of the oil cooler.  Is that why Mooney relocated the oil cooler behind #4 cylinder on E’s and F’s?  Why not the same mod for the C… because the battery box was in the way?  What is the function of this mod (pic below)… does it decrease airstream pressure on the front of the oil cooler and improve reverse airflow out the front of the oil cooler?

Sorry about the thread drift… 

 

[Shadrach]

3 hours ago, 47U said:

How much does air flowing through the cylinder fins heat the air therefore expanding the volume?  

Is there a (significant?) change in pressure in the upper cowl depending on where the heat muff cold air inlet is located?  Early C’s tap this air from behind #3 cylinder.  Later C’s take the air from in front of #2 cylinder.  My friend has a G, the heat muff air is tapped from the lower deck, below the cylinders, in front of #2.  Were these changes made only to improve the organization of the ducting to support carb and cabin heat?

Later C’s had fixed cowl flaps.  Then I saw a later C on the ramp and it had a small set of louvers in both cheek cowls.  Obviously, to improve airflow out of the lower deck.  If the oil cooler outlet was ducted to a similar louver in the cheek cowl, would oil cooler effectiveness and overall better airflow out of the lower deck resulting in lower CHTs? 

What about the oil cooler?  I’ve read that it’s possible to have reverse airflow from the lower deck out the front of the oil cooler.  Is that why Mooney relocated the oil cooler behind #4 cylinder on E’s and F’s?  Why not the same mod for the C… because the battery box was in the way?  What is the function of this mod (pic below)… does it decrease airstream pressure on the front of the oil cooler and improve reverse airflow out the front of the oil cooler?

Sorry about the thread drift… 

 

Louvers likely meant there was a RayJay turbo underneath.

If memory serves, my 67 F has an opening above #3 that serves as a blast tube for the accessories. There is an opening above #4 that feeds 1” SCAT that cools the mechanical fuel pump.

The fresh air intake for the heat exchanger is underneath cylinder #2. It gets a direct supply of ram air but it will put some heat into the cabin from prop wash alone. I’ve always wondered how the ARI lower cowl enclosure works with the heat intake in front of #2; It seems to block direct airflow. I wondering if that affecting @Ragsf15e heat output?

 

[A64Pilot]

5 hours ago, N201MKTurbo said:

Remember that air flows because of pressure. When the pressure in the upper cowl exceeds the dynamic pressure in front of the cowl, no more air will flow into the cowl, it will just go around it. 

You can actually turn velocity into pressure and vice versa. If there is reverse flow out of the inlet, then of course there is reverse flow of the entire system, meaning air flow in through the cowl flaps. You can’t have air flowing out of both ends

You could get outflow through part of the inlet if that part was shielded from the ram pressure by an object being well in front of the opening but nothing blocks part of the Guppy mouth does it? There is only a small gap between the spinner.

Ref inlet vs outlet size, you want the inlet bigger if you want to build velocity in the system, you want it smaller if you want to build pressure. This is how velocity and pressure can be manipulated by inlet vs outlet size, just like a carburetor, the middle section is smaller increasing velocity and decreases pressure.

Next time you walk by a turbine look at its inlet, it gets bigger towards the engine, being a reverse funnel if you will makes it build pressure by decreasing velocity.

More modern cowls decrease drag by being more efficient in flow, first they are round, because a circle has the greatest interior area with the smallest exterior, so round pipes flow more water than any other shape, so they have round inlets and to heck with the esthetics. Bigger odd shaped holes are draggier if that’s a word, A J’s inlets are better than the Guppy but the knowing didn't go for least drag I guess for appearance. In the 10970’s I guess people weren’t ready for round holes? As was brought up, what’s inside is very important too, any restriction to airflow is drag of course, drag is proportional to the airflow, open the cowl flaps increases drag, I think we all understand that