# Comparisons of aircraft weight fractions.



## Shortround6 (Nov 24, 2009)

A thread for the comparison of various weight fractions of aircraft.

As in Bf-109E-4, Gross loaded 5520lbs, fuel 88imp gallons at 7.5lb per gallon equels 660lbs.
Fuel fraction = 11.9% of gross

And armament weight ( guns and ammo) of 149kg=327.8lbs

bare (net) armament weight fraction=5.9%
Gross armement weight=7.7-9.5% depending on allowances for mounts, boxes, chutes, heaters, etc.

Something like this?


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## drgondog (Nov 24, 2009)

Away from my good sources but here is a start for the Mustang

P-51A/Mustang II = basic weight including Allison but otherwise empty of all fuel, oil, ammo = 6,800
P-51B/C/Mustang III = 7010 = basic difference between Allison and Merlin (including structure and extra cowling, dropping wing, etc)

The primary differences between Allison and Merlin Engines
Allison = 1335 pounds built up 
Merlin 1650-3 and -7 = 1690 pounds built up.
Merlin 1650-9 = 1745 pounds built up

*My weights do NOT include radiator core or oil cooler - all those are lumped into the airframe weight. Thw Allison and Merlin figures are for the engine as it would be composed and yanked from an airplane 100% intact including supercharger and carb*.

Total Basic Weights before Ammo,Mission loading of fuel/oil and pilot
P-51 = 6450 
P-51A = 6800 
P-51B/C = 7010 
P-51D/K = 7635
P-51H = 7148 

Fuel capacity
Mustang I 170 gallons ~ 1020 pounds
P-51, P-51A , A-36 180 gallons ~ 1080 pounds
P-51B-1 184 gallons ~ 1184 pounds
P-51B/C/D 184 + 85 gallons ~ 1614 pounds
P-51H 205 + 50 Gallons ~ 1530 pounds

Guns (include in basic weight above)
100pounds each for 20mm = 400 pounds
69 pounds each for 50 cal = 276 pounds A/B/C
69 pounds each for 50 cal = 414 pounds D/K/H

Ammo
P-51 500rounds 20mm= 300 pounds
A-36 1200 rounds .50 = 400 pounds
P-51A,B, C 1260 rounds = 420 pounds
P-51D/K 1880 = 626 pounds
P-51H 1820 rounds = 607 pounds

Total Armament 
P 51 = 700 pounds
P-51A/B/C = 696 pounds
P-51D/K = 1040 pounds 
P-51H = 1021 pounds


75 gallon external = 1040 pounds
110 gallon external = 1490 pounds
150 gallon external = 2060 pounds
165 gallon external = 2240 pounds

Pilot = 200 pounds w/chute etc

I gotta go - subtract the Allison built up weight plus guns to get basic airframe w/o engine and fuel and guns and ammo

I just edited to get a complete breakout by airframe type... but I think my 'basic weight' for each airframe does include gun installation (but not ammo). Page 190 Gruenhagen..

So, the built up mission weights for nominal take-off full internal fuel, ammo, oil and pilot are:

P-51 = 8030
P-51A = 8500
P-51B = 9244 (incl 85 gal fuse tank full)
P-51D = 10075 (incl 85 gal fuse tank full)
P-51H = 9485 (incl 50 gal fuse tank full)

So P-51
% engine wt to Mission load = 1335/8030 = 16.6%
% Armament wt to Mission load = 700/8030 = 8.7%
% Fuel (internal) to Mission Load = 1080/8030 = 13.4%

P-51B/C
% engine wt to Mission Load = 1690/9244 = 17.7%
% Armament wt to Mission Load = 696/9244 = 7.5%
% Fuel wt to Mission Load = 1614/9244 = 17.5%

P-51D
% engine weight to Mission Load = 1690/10075 = 16.8%
% Armament wt to Mission load = 1040/10075 =10.3%
% Fuel to Mission load = 1614/10075 = 16 %

P-51H
% engine wt to Mission Load = 1745/9485 = 18.4%
% Armament load to Mission wt = 1021/9485 = 10.8%
% Fuel to Mission load = 1530/9485 = 16.1 %

Add the external 110 gallon tank weight to ammo, internal fuel, and pilot weights to get the estimated Max Gross weight at Take off for P-51B/C/D/K/H.


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## Shortround6 (Nov 26, 2009)

Sorry, I have been neglecting this thread. 

Thank you for the Mustang Figures.

Here are some other American fighters.

P-39D
gross weight normal……....7698lbs
Empty weight ……………....5658lbs
Useful load……………………..2040lbs = 26.5%
Armament weight…………..1100lbs = 14.2%
Fuel (104 gal)………………....624lbs = 8.1%
Power plant…………………..2394lbs = 31%

Normal weight is without drop tank, armament weight includes armament provisions ( at least some) and is for 37mm version, ammo included. Power plant includes engine, accessories, controls, propeller , cooling system and oil system (without oil) but NOT the Fuel system. In the P-39 the fuselage takes the place of the cowl and engine mounts.

P-40C
Gross weight normal…………...7504lbs
Empty weight …………………….5767lbs
Useful load………………………….1737lbs
Armament weight…………….....596lbs (net) = 7.9%
Fuel (120gal) ……………………...720lbs = 9.6%
Power plant………………………..2527lbs = 33.6%

Normal weight is without drop tank, armament weight is without any provisions (mounts, boxes, chutes etc) . Power plant is as above. Except cowl , engine mounts, etc are included in power plant weight. 

P-40E
Gross weight ………………………8290lbs
Empty weight …………………....6069lbs
Useful load…………………………..2221lbs
Armament weight…………….....903lbs (net) = 10.9% 
Fuel (148gal)………………….......888lbs = 10.7%
Power plant………………..….....2565lbs = 30.9%

Normal weight is without drop tank , everything else is as above.

P-47D (early)
Gross weight ………………..13582lbs
Empty weight ………………..9957lbs
Useful load……………………..3625lbs
Armament weight ………….1237lbs (net) = 9.1% (267rpg)
Fuel (305 gal) ………….…….1830lbs = 13.5%
Power plant………………… ..4371lbs = 32.2%

Normal weight is without drop tank , everything else is as above. 
Power plant weight is without water injection and with the narrow propeller.


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