Energy efficiency of North American P-51 Mustang

Updated Nov 5, 2020

The North American P-51 Mustang:

• flew around 0.073—0.092 m/kJ
• and moved mass at around 0.25 – 0.50 kg.m/J

Details

The North American P-51 Mustang was a 1940 US WWII fighter and fighter-bomber.¹

Mass

According to Wikipedia²:

• Empty weight: 7,635 lb (3,465 kg)
• Gross weight: 9,200 lb (4,175 kg)
• Max takeoff weight: 12,100 lb (5,488 kg)

We use the range 3,465—5,488 kg, since we do not know at what weight in that range the relevant speeds were measured.

Distance per Joule

Wikipedia tells us that cruising speed was 362 mph (162 m/s)³

A table from WWII Aircraft Performance gives combinations of flight parameters apparently for a version of the P-51, however it has no title or description, so we cannot be confident. ⁴ We extracted some data from it here. This data suggests the best combination of parameters gives a fuel economy of 6.7 miles/gallon (10.8km)

We don’t know what fuel was used, but fuel energy density seems likely to be between 31—39 MJ/L = 117—148 MJ/gallon.⁵

Thus the plane flew about 10.8km on 117—148 MJ of fuel, for 0.073—0.092 m/kJ

Mass.distance per Joule

We have:

• Distance per kilojoule: 0.073—0.092 m/kJ
• Mass: 3,465—5,488 kg

This gives us a range of 0.25 – 0.50 kg.m/J

Primary author: Ronny Fernandez

Notes

1. The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in April 1940 by a design team headed by James Kindelberger^[6] of North American Aviation (NAA) in response to a requirement of the British Purchasing Commission.”

   “North American P-51 Mustang.” In Wikipedia, October 19, 2020. https://en.wikipedia.org/w/index.php?title=North_American_P-51_Mustang&oldid=984347874.

2. “North American P-51 Mustang.” In Wikipedia, October 19, 2020. https://en.wikipedia.org/w/index.php?title=North_American_P-51_Mustang&oldid=984347874.
3. “North American P-51 Mustang.” In Wikipedia, October 19, 2020. https://en.wikipedia.org/w/index.php?title=North_American_P-51_Mustang&oldid=984347874.
4. “P-51D_15342_AppendixB.Pdf.” Accessed November 5, 2020. http://www.wwiiaircraftperformance.org/mustang/P-51D_15342_AppendixB.pdf.
5. Wikipedia lists energy densities for a variety of fuels, and those for petroleum, 100LL avgas, diesel, and jet fuel are within this range and seem likely to be similar to that used.

   “Energy Density.” In Wikipedia, September 21, 2020. https://en.wikipedia.org/w/index.php?title=Energy_density&oldid=979608484.