View Full Version : What kind of fuel mileage does a typical jet get
I was watching Monster Garage the other day, and they were basically putting a Jet Engine on a Toyota celica. The guy putting it in, I could have swore he said that at 200mph, it would burn 300 gallons of fuel a mile. I thought I had to have misunderstood this, but my brother sad that is what he heard also.
Is the fuel mileage on a jet really that crappy? 200mph is probably a cruising speed for jets in the air(at least by my totally uneducated guess).
Just something that sparked a thought, anyone that has a answer, it'd be appreciated...
It varies greatly, but the typical passenger jet (727,737, MD-80, etc.) will burn 3000-4000 pounds of fuel, per hour, per engine at cruise altitudes. So we are talking about, lets say, 7000lbs/hour for a typical two engine passenger jet. At 6lbs/gallon, that around 1150-1200 gallons per hour.
Ground speed also varies greatly, depending on the wind, but lets use 450KTs. That's around 2.5 gallons/nautical mile.;P
remeber also that the engine installed in the car also was using the afterburner. this creates an exponetial increase in fuel flow. i had a professor that flew F-4's that mentioned if they were below 2000ft in full afterburner that the aircraft would run out of fuel in just over 2 minutes.
the other factor is that the engine in the car was being operated in this condition at sea level. a jet engine becomes more effective as it's altitude increases. less air at altitude allows the engine to use less fuel. this is the reason that you'll have a climb/cruise/descent profile to follow to give the performance that your looking for.
the engines that are mounted on your passenger airliners are not a true jet engine, they are a turbofan. in this type of engine most of the thrust is created by the fan section vs. the jet exaust. the jet is what keeps the fan turning. these engines can be truely incredible when comparing thier capabilities against the fuel required.
that was a truely awsome car though;f
Twin engine jet helicopter Dauphine we burn 100 gallons an hour.That's at cruise or on the ground at full throttle.;P
That's around 2.5 gallons/nautical mile
Keep in mid that that is not as bad as it sounds. A 737, e.g., carries 100-189 passengers. So per passenger the it's about .0025-.0013 g/nM/passenger. That would be 400-800 miles per gallon per passenger. However, now that I look at it I think there might be a decimal point off some where. I think I recall the right number to be about ten times higher. Don't have time to figure it out now. Later.
Originally posted by flyboy5432H
that was a truely awsome car though;f
Yes it was.
Like I said, I know didly about aviation, but I figured someone here would know wether that guy was "talking to the camera", or if it was a logical estimate. Seems it was a fairly logical estimate...
I bet they never pass a gas station in that thing...lol
Our 747-400's burn 186 kgs per minute and fly 8 miles per minute when loaded to the hilt, or structual weight of 394,625 kgs or 868,175 lbs.
I don't know alot about jets or turbo fans but don't they burn a lot more fuel at take off throttle that as cruising throttle or cruising speed? I mean, not only getting to speed, but getting there quickly and climing.
So since this jet was on a car he has much less fuel than an airplane. And he doesn't have much room to work with so he wants to get to speed as quickly as possible so I would imagine that he would have the throttle wide open, or as wide open as was safe or practical for the car.
Originally posted by lomfs24
I don't know alot about jets or turbo fans but don't they burn a lot more fuel at take off throttle that as cruising throttle or cruising speed? I mean, not only getting to speed, but getting there quickly and climing. Yep. Flyboy mentioned that earlier. That's also another reason why I would see the Alert KC-135's launch just prior to the B-52's when the klaxxons sounded. :)
My little dodo bird gets about .155lbs/nam.. so that's about one mile to the gallon. That's a rolling average for the trip as calculated by the FMS. A straight cruise milage would be more like 400ktas divided by 2000lbs (about 300gal) an hour...
0-120 in about 10 seconds then pitched to a 20-25deg deck angle is worth it, though!
We just don't cruise fast... ;e
The Tomcat A would burn between around 2200 lbs/hr/side through 5000+ lbs/hr/side, depending how fast we wanted to go. If we needed to get rid of gas, the fastest way was to select grunt and "turn dead dinosaurs into noise" at a rate of over 4000 lbs/min; it was even faster than dumping (and a lot more fun).
I know some about aircraft, but a lot more about Jet powered dragcars. I've worked on a few, piloted a few and helped build a few. Most are Pratt Whitney JP-12s, JP-38s or GE J34s. There are others.
Most will go through about 20-30 gallons of fuel on a 1/4 mile pass. That includes start up, the "fire show" and running down the track. Actual fuel flow on some of the 300 mph jet cars says about 10-15 gallons of fuel in 6 seconds. So 100 gallons/minute. Thrust is from about 5,000 to 9,000 pounds which puts HP at 7,000 to 15,000 HP.
From this, his numbers appear to be a tad high, considering that these are top of the line dragsters with well tuned engines.
The jet track dryers use about 5-10 gallons/minute at wide open.
Here is a useless factoid that always amuses me (useless unless you are the poor sap with the credit card at the pump with this thing!)
The following two notes came to the keeper of the WARS Web site via an old friend, Jim Davis - aka Retired Government Clerk. They are reproduced below exactly as received. The e-mail addresses of the correspondents have been removed to protect their privacy. To better understand the two notes here is a brief explanation of some of the abbreviations used:
QB = Quiet Birdman: A fraternal order of airmen
CG = Center of gravity
SCA = Shuttle carrier aircraft
TAS = True airspeed
#/hr. = Fuel flow in pounds per hour
ROPESTART 747 = Pilot-speak for the B747 -100, -200, and -300, because those
models are so old it's said you have to wrap a rope around the engine and give it
a yank to get it started. The manufacturer and airline companies prefers to refer
to those early models as the "747 Classic".
From Bill Caddoo:
I was having a discussion with Ed Lewis, SFO QB and a NASA test pilot at
Edwards AFB, about flying the ropestart 747 for United Airlines, and
wondering just how the darn thing flys with the Space Shuttle mounted atop
the 747. Ed works with Astronaut Gordon Fullerton who almost exclusively
flys the NASA 747 with the Shuttle attached after it lands, and he has to ferry
it back to Florida for another launch.
I knew they flew fairly low altitude, less than 20,000 feet, but never knew just
why. I also knew they gobbled fuel and had to make several fuel stops
between California and Florida. I'd seen the plane at El Paso, Amarillo, ABQ,
and Ellington AFB (Houston) several times in my airline and military travels.
I also wondered about the handling qualities of the plane, with that big mass on
top, disrupting airflow, causing drag above the CG of the aircraft, ability to flare
and land, etc.
Ed passed my curiosity along to Gordon Fullerton, and I have included
Gordon's reply below.
Notice the last line which references his 'fuel mileage'.... your mileage may vary!
SCA stands for Shuttle carrier aircraft -- a NASA Boeing 747 that used to
belong to American Airlines.
Subj: SCA handling qualities
Date: 07/16/2000 1:37:54 PM Pacific Daylight Time
From: (Gordon Fullerton)
To: (Lewis, Ed) (Dan)
The SCA with an orbiter attached, for mild maneuvering, doesn't handle all that much differently than in the clean configuration. There is a constant rumbling buffet from the orbiter wash hitting the vertical stabilizer, not uncomfortable, but always there.
Roll response and pitch response seem about the same. Turn coordination is affected. With bank angles of more than 10-15 deg, reverse (with the turn) rudder is required to keep the ball centered.
There is a noticeably greater pitch trim change with power change. When trimmed on final, which requires a greater power setting because of the drag, and subsequent reduction to idle during the flare, you must be prepared for a greater than normal pull force to keep from dropping in. The biggest effect is of course drag. Typical ferry conditions are at 15000
ft (to keep coolant fluids in the orbiter from freezing), 310 knots TAS, fuel flow 39000 #/hr. Another way to state it, mileage is about 325 ft per gallon.
My only quesion is - dosn't that coolant also have a slight tendancy to freeze in, uh SPACE???
SR-71 , 8ooo gal per hour
Each j58 burns 4ooo gal per hour (apx 1.11 gal per sec )
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