Curtiss XP-37/YP-37

[wuzak]

Yes, in both Curtiss and Hawker's cases they thought the ventral location would be a low drag layout, but in both cases it didn't work.

[KJ_Lesnick]

wuzak

Yes, in both Curtiss and Hawker's cases they thought the ventral location would be a low drag layout, but in both cases it didn't work.

If I may ask, why?

[rickshaw]

wuzak

Yes, in both Curtiss and Hawker's cases they thought the ventral location would be a low drag layout, but in both cases it didn't work.

If I may ask, why?

Because it looked better there, in their opinion?

Because their calculations suggested it worked better there?

Because it balanced the design?

Who knows?  Sometimes you ask silly questions which annoy people because they don't know/don't care about what are, in reality quite trivial matters and more than likely were only discovered not to work through experience.

I can think of three aircraft that a mid-mounted radiator didn't work on - Tornado, Ki-60 and P-40 and two where it did work - P-51, Hurricane.   Why did it work on two and not on the three?  I have no idea but I suspect it was the design of the radiators, it's interference with the airflow and it's shape, rather than necessarily it's actual location.  It's like air brakes.  Hawker's learnt early on, you put a big airbrake on a jet fighter on the bottom, three quarters towards the rear of the fuselage.  It worked on the Hunter and so they've stuck to that location on the Harrier and the Hawk.   McDonnel Douglas learnt to put them on the top in the F-15.  Two different solutions to the same problem.  Both locations prevent pitching and improve stability.

[wuzak]

I suspect that Hawkers did it on the Tornado because the Hurricane had it there. As did the biplane Fury.

As for Curtiss, I think Rickshaw's guesses are as good as any.

Or it could have been because the weight balanced better with the radiator there, requiring fewer balance weights.

Or that they needed some extra work for their design and detail draughtsmen.

Rickshaw, I think the MIG-1, -3, the Yak -1, -3, -7 & -9 all worked.

Curtiss's own XP-46 seemed to work ok, though its performance was no improvement on the P-40.

It also seemed to work ok on the Curtiss XP-60. Though that was more forward, but still not under the chin.

[tomo pauk]

The 'mid fuselage' radiators on the Hurricane worked that much they served the function, sticking them on the slipstrem was like having a dive/speed brake deployed. The Yaks, LaGG-3, Ki-61, D.520, MC.205 and G.55 have had half-burried coolant radiator, the D.520 later (late 1940/early 1941? in production for Vichy) received the boundary layer splitter similar to what P-51 had.

[KJ_Lesnick]

rickshaw

Because their calculations suggested it worked better there?

If so, why didn't it work in practice?  If you were venture a guess, would you say it would have been

• A variable they failed to factor in
  
• A variable they did not understand
  
• A scaling issue
  

Because it balanced the design?

I would assume you mean center of gravity right?

Because it looked better there, in their opinion?

Was it common in those days to use aesthetics to gauge performance?

Sometimes you ask silly questions which annoy people because they don't know/don't care about what are, in reality quite trivial matters and more than likely were only discovered not to work through experience.

Well, they didn't have a trivial effect on performance evidently: You're right probably that experience played a role, though there were cases, such as the YF-102, where knowledge on area ruling existed prior to it's flight

- The knowledge existed in nautical engineering design: It would appear those who worked on boats rarely worked on aircraft
- The Germans looked into it as early as 1944: It's not clear if this knowledge was readily disseminated to the US aerospace industry
- Some aircraft designers did look into V-tails due to interference effects between the fuselage and tails (which were essentially caused by the airflow over the fuselage and tails combining together to produce unusual shockwave strength)
- In 1947 Wallace D. Hayes wrote a doctoral thesis on it: I forgot why it didn't get any attention, but I remember there was an explanation though

I may very well be perceived by some as a geek :p

I can think of three aircraft that a mid-mounted radiator didn't work on - Tornado, Ki-60 and P-40 and two where it did work - P-51, Hurricane.   Why did it work on two and not on the three?  I have no idea but I suspect it was the design of the radiators, it's interference with the airflow and it's shape, rather than necessarily it's actual location.

Logical enough

It's like air brakes.  Hawker's learnt early on, you put a big airbrake on a jet fighter on the bottom, three quarters towards the rear of the fuselage.  It worked on the Hunter and so they've stuck to that location on the Harrier and the Hawk.   McDonnel Douglas learnt to put them on the top in the F-15.  Two different solutions to the same problem.  Both locations prevent pitching and improve stability.

I guess it makes sense that manufacturers have preferences -- after all from the F-88 to the F-4 the engine position was very similar: With the F-4 an aviator said to the effect that the plane looked like somebody stomped on it's nose and kicked it in the donkey

[rickshaw]

rickshaw

Because their calculations suggested it worked better there?

If so, why didn't it work in practice?  If you were venture a guess, would you say it would have been

• A variable they failed to factor in
  
• A variable they did not understand
  
• A scaling issue
  

Possibly all three, more than likely just two.

Because it balanced the design?

I would assume you mean center of gravity right?

Balance of weight/balance of aesthetics/balance of art?

Because it looked better there, in their opinion?

Was it common in those days to use aesthetics to gauge performance?

As much as anything.  They worked out a design and then built it and, "Lo and behold!  It worked or it didn't!"...  They didn't have extensive wind tunnels and numerous tests to try out a design before they built it, Robyn/Kendra.

Sometimes you ask silly questions which annoy people because they don't know/don't care about what are, in reality quite trivial matters and more than likely were only discovered not to work through experience.

Well, they didn't have a trivial effect on performance evidently: You're right probably that experience played a role, though there were cases, such as the YF-102, where knowledge on area ruling existed prior to it's flight

- The knowledge existed in nautical engineering design: It would appear those who worked on boats rarely worked on aircraft
- The Germans looked into it as early as 1944: It's not clear if this knowledge was readily disseminated to the US aerospace industry
- Some aircraft designers did look into V-tails due to interference effects between the fuselage and tails (which were essentially caused by the airflow over the fuselage and tails combining together to produce unusual shockwave strength)
- In 1947 Wallace D. Hayes wrote a doctoral thesis on it: I forgot why it didn't get any attention, but I remember there was an explanation though

I may very well be perceived by some as a geek :p

Yes.  You sometimes show you have knowledge but you rarely seem to apply it...

[KJ_Lesnick]

rickshaw

Possibly all three, more than likely just two.

Okay

Balance of weight/balance of aesthetics/balance of art?

"It looked right" basically?

They didn't have extensive wind tunnels and numerous tests to try out a design before they built it, Robyn/Kendra.

So, there was a lot more guesswork?

Yes.  You sometimes show you have knowledge but you rarely seem to apply it...

I'm not that knowledgeable on piston engines: Most of my knowledge on aircraft starts at the tail end of WWII to the 2000's