P47m vs. P-47n: Round II

[LLogann]

This is true!  Same engine (more or less.... 2800-57 vs. 2800-77 I think) but not the same airframe.     There are so many differences between the N and the M I find it silly to try and single out any one thing.

Krusty I'm not as certain as you seem to be that all of the drag difference is based on weight.

[Krusty]

There are not THAT many differences. The main ones being the wing. A bit longer and more squared. More wing area. The rest of the differences in the airframe (in the fuselage area I mean) are minor by comparison.


FLS, surely you're right. I was attempting to simplify it for comparison's sake. The extra wing area has more parasitic drag, if I've got my terms correct. That probably contributes PART of this 10mph difference. However, 10mph isn't much. You could have 10mph variation out of the factory and still be within acceptible specifications for the military to accept it.

[bj229r]

N DOES seem to dive better than any of them (the squared off wings?)

[Krusty]

I'd think the extra weight helps more in a dive. The wings were squared, but longer.


Plus, I read some comment somewhere about rounded wingtips being less drag.

[Wildcat1]

ive always been fond of the D-25.

[LLogann]

But you're cool with saying it's the same exact engine?  

I'd think the extra weight helps more in a dive. The wings were squared, but longer.


Plus, I read some comment somewhere about rounded wingtips being less drag.

EDIT:

LLogann can't find an IDIOT SMILEY.

[Stoney]

Krusty I'm not as certain as you seem to be that all of the drag difference is based on weight.

I would say the majority of it was, as the difference in empty weight was considerable; if you consider the altitudes at which both planes reached their highest speed, induced drag from weight would be reaching extremes.  Like Krusty said, there is a bit of extra wing area on the Jug-N, but I would guess, without doing any of the hard math, that the extra weight made up the biggest proportion of whatever combination of factors made the Jug-N slower.

[Stoney]

This is true!  Same engine (more or less.... 2800-57 vs. 2800-77 I think) but not the same airframe.     There are so many differences between the N and the M I find it silly to try and single out any one thing.

It really was just the wing construction that changed.  Fuselage didn't change.

[Lepape2]

Are the attachments for rockets present on the M's wings? If not, that would account for most of the aerodynamic drag not fully associated with weight and wing span alone on the N. If its all about wing span or wing area, then if there is more lift, there is more drag.

[Stoney]

Are the attachments for rockets present on the M's wings? If not, that would account for most of the aerodynamic drag not fully associated with weight and wing span alone on the N. If its all about wing span or wing area, then if there is more lift, there is more drag.

No rocket stubs were ever added to a service-condition M that I know of.  I doubt it was ever even tested, as the "factory" condition (it was supposedly an air-to-air only design) for the M was no pylons and six guns.  Of course, the 56th went ahead and added the pylons and the extra guns in the field.

[FLS]

I would say the majority of it was, as the difference in empty weight was considerable; if you consider the altitudes at which both planes reached their highest speed, induced drag from weight would be reaching extremes.  Like Krusty said, there is a bit of extra wing area on the Jug-N, but I would guess, without doing any of the hard math, that the extra weight made up the biggest proportion of whatever combination of factors made the Jug-N slower.

I agree Stoney, my comment was regarding Krusty's assertion, since corrected, that the drag difference was all from the extra weight, which at almost 1000 lbs or 10% difference,  is obviously a considerable amount. I think the hardpoints on the N, which I don't believe were on the M model in the test that Crusader was referring to, and the wing differences, also contribute to the drag difference.

[Seadog36]

It is a lesser known fact that Ns were first deployed to Europe, but to to delays in their assembly were not available until after the war was over in that theater. They were then re-dissembled and shipped to the Pacific.

It was also assessed that in spite of the wing root extensions the squared off wing tips gave the N a better roll rate than the M.

The Air Force also wanted the (P)F-47 for ground attack in Korea but due to a shortage of spare parts the less suitable (P)F-51 was used for ground attack.

[Lepape2]

Although I do believe the M has the same wing shape as the D-40 and I couldn't find a suitable comparison print of N VS M, I stacked up the N(In green) over a D-40(In Red). Yellow lines are overlapping lines.

What strikes the most is the gun separation and especially the flap area. In stall fights, flaps will prove to be much more effective but also more energy hungry albeit the increased weight of the N model. Other differences include propeller hub, antennas, tail fin, hardpoints, wing fuel tanks, engine power output, and of course weight.


Sources:
http://www.mnbigbirds.com/images/3%20Views/P47/P-47N%201%20RE.jpg
http://www.mnbigbirds.com/images/3%20Views/P47/P-47D%2040%20RA%20Rt%20Side.jpg

[Krusty]

I agree Stoney, my comment was regarding Krusty's assertion, since corrected, that the drag difference was all from the extra weight,

What do you mean 'since corrected?' I believe I was correct to begin with? 

[Krusty]

But you're cool with saying it's the same exact engine?  

Stoney has already answered, but...

47M here shown with R-2800-57
http://www.wwiiaircraftperformance.org/p-47/p-47m-republic-wepchart.jpg

47N shown here with R-2800-57
http://www.wwiiaircraftperformance.org/p-47/p-47-differences.jpg

47N here shown (section III B) as R-2700-57
http://www.wwiiaircraftperformance.org/p-47/p-47n-88406.html

47M here listed as comprising the 47N fuselage and D30 wing (R-2800-57 listed for 47N on same page)
http://www.wwiiaircraftperformance.org/p-47/p-47-differences.jpg