Positive thrust to weight ratio.

USMCmech

Well-Known Member
Can one of you guys tell me which airplanes have a positive T/W ratio? I had another pilot tell me that the F-18 does. I told him it dosen't (no ordance and a light fuel load it's close). I have a 6 pack riding on the answer.

I know the F-16 and the F-15C do, and suposedly the SU-27 (I think).

I guess you could say the AV-8B does too, but only with a very light load.
 

Minuteman

“Dongola”
According to The Wikipedias

Code:
[B]Vehicle		T/W 	Scenario[/B]
Concorde	  .373	
F-15 Eagle	 1.04	nominally loaded
F-16 Falcon	 1.096
Hawker Siddeley	 1.1
  Harrier
Dassault Rafale	 1.13
Mikoyan MiG-29	 1.13
Eurofighter	 1.18
  Typhoon 
English		 1.2
  Electric
  Lightning
Space Shuttle	 1.5 	Take-off
F-15 Eagle	~1.6 	max
Space Shuttle	 3 	Peak (throttled back for astronaut comfort)

Also according to Wikipedia for the F-18's:

Dry thrust: 11,000 lbf each (22,000 lbf total)
Thrust with afterburner: 17,750 lbf each (35,500 lbf total)

Empty weight: 24,700 lb (10,800 of fuel and load to stay above 1)

Or, if you take the stated wing area and wing loading as a "typical weight", you get 400 ft² times 93 lbf/ft² = 37,200 lb ... which makes the F-18's thrust-weight ratio about 0.95

MTOW is stated as 51,550 lb
 

fish314

Well-Known Member
[FONT=Arial, Arial, Helvetica]Schweitzer 2-33[/FONT]
Actually, even the 2-33 doesn't have a negative ratio. (Zero is neither positive nor negative).

I suppose any aircraft with a thrust reverser could have a negative thrust to weight, but only if it's in reverse!
 

Hacker15e

Dunning–Kruger Observer
The question really is...."at what weight".

At any kind of actual combat fighting weight (in other words, with tanks, bombs, missiles, and full fuel) they're not doing the much-revered "accelerating straight up".

I've flown a stripped-out F-15E with -229 engines, which has a better than 1:1 ratio, and it's pretty fun until you have to do something more tactical than go fast and turn tight -- like shoot someone.
 

frog_flyer

FredFlyer
The question really is...."at what weight".

At any kind of actual combat fighting weight (in other words, with tanks, bombs, missiles, and full fuel) they're not doing the much-revered "accelerating straight up".

I've flown a stripped-out F-15E with -229 engines, which has a better than 1:1 ratio, and it's pretty fun until you have to do something more tactical than go fast and turn tight -- like shoot someone.
Not a problem for the F-15C guys.

Zing!
 

Low_Level_Hell

Well-Known Member
Blackhawks, Apaches, Chinooks, and on a cold day even Kiowas.



Shouldn't the question be aircraft with greater than a 1:1 ratio?
 

Minuteman

“Dongola”
So what airplanes have a negative thrust to weight ratio ;)
I noodled on this for a while and finally had to concede that there is no getting around the fact that thrust and weight are just magnitudes, so the ratio is also just a number. Once you start saying "positive" or "negative", you're making 'em vectors. No Timmy, not even for buoyant vehicles.

On the other hand, what aircraft can have a positive dot product for thrust and drag? Maybe the Multiple Kill Vehicle!

[YT]LC97wdQOmfI[/YT]

[YT]W1HCFM9yoKo[/YT]

[YT]hRBoTcHOzOU[/YT]​
Oops, wrong video... :p
 

ppragman

FLIPY FLAPS!
I noodled on this for a while and finally had to concede that there is no getting around the fact that thrust and weight are just magnitudes, so the ratio is also just a number. Once you start saying "positive" or "negative", you're making 'em vectors. No Timmy, not even for buoyant vehicles.

On the other hand, what aircraft can have a positive dot product for thrust and drag? Maybe the Multiple Kill Vehicle!
[yt]LC97wdQOmfI[/yt]

[yt]W1HCFM9yoKo[/yt]

[yt]hRBoTcHOzOU[/yt]​
Oops, wrong video... :p

The MKV is freaking awesome, I got to see more.
 
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