Thrust? - AR15.COM

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Posted: 11/15/2018 11:28:35 PM EDT

Just curious exactly how much thrust modern jets make and how that power is put to the ground or air as it were. I know engines have ratings but for example, would a fully loaded passenger jet, say a 737 with the brakes fully set move forward if the engines were powered up, basically skidding the locked up tires on dry runway? If so would all jets be capable of doing it? If not, are any capable? Yeah, I know it's not something anyone would do but just curious what would happen. Think of it as a brakestand in a plane.

Posted: 11/15/2018 11:41:34 PM EDT

[#1]

Do a little Arfcom research. It depends on if it's on a treadmill or not.

Posted: 11/15/2018 11:42:01 PM EDT

[#2]

Has a engine engineer tell me that idle for a jet is about 80% thrust. So full throttle only adds the last 20%. Not saying this answers your question but just food for thought.

Posted: 11/16/2018 12:03:12 AM EDT

[#3]

Since it's what I'm currently flying, I'll use the 737-800 numbers.

Normal Maximum takeoff thrust is 26,000 pounds of thrust, per engine. Under certain circumstances we can "bump" that to 27,000 per engine.

The maximum structural takeoff weight is 174,200 #'s. So it's not exactly a rocket. I do believe the brakes will hold the airplane at full power, but I've never done it.

Posted: 11/16/2018 12:08:33 AM EDT

[#4]

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Has a engine engineer tell me that idle for a jet is about 80% thrust. So full throttle only adds the last 20%. Not saying this answers your question but just food for thought.

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That’s no where near correct.

One thing pilots hate is high idle thrust and holding the brakes against it.

Just for that reason, engine specs typically require a very low idle thrust.

Now here is what he might have meant and a number that some may find incredible: a turbine (core speed) will idle somewhere around 70-80% of its max speed; to use an old ICE term, turbines don’t “get on the cam” until they get to high RPM.

I don’t know if they go to full max power, but I’ve been in C-17s that, during short field/heavy ops, go to high thrust settings against the brakes and then release them; I assume they are at max power since once the engines spool up, no further change in engine noise or felt thrust occurs after brake release.

Posted: 11/16/2018 12:34:50 AM EDT

[#5]

We had 33,000 thrust on our 737-300’s with CFM’s. Brakes would hold but she sure shook like hell!

Posted: 11/16/2018 1:24:23 AM EDT

[#6]

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We had 33,000 thrust on our 737-300's with CFM's. Brakes would hold but she sure shook like hell!

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The 737-700s and -800s that I worked on were like that as well. I've been in on a few full power engine runs on the run-up pad, and it was hard to read the maintenance manual for whatever check we were doing.

Fun fact: The engines I worked on were rated for between 21,000 and 28,000 pounds of trust. While they had different power ratings, they were physically the same engine. It was a little plug inserted into a port on the computer on the side of the engine that told it how much power the engine was allowed to make.

Posted: 11/16/2018 2:09:35 AM EDT

[#7]

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We had 33,000 thrust on our 737-300’s with CFM’s. Brakes would hold but she sure shook like hell!

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Back in the day at Orange County doing a noise abatement TO, we held the brakes at max thrust on 73's. "But she sure shook like hell!" Good times.

Posted: 11/16/2018 2:20:46 AM EDT

[#8]

My Learjet produces 3500# of thrust per engine. Above 75% power I have to stand on the brakes hard enough to almost lift me off my seat. Above 90% power my brakes won’t hold the plane.

Posted: 11/16/2018 9:13:25 AM EDT

[#9]

From a maint. view point almost all of the ground performance runs I have done were unloaded and low fuel.
In my experience a King Air 200 will jump a small nose wheel chock and accelerate pretty rapidly dragging all 4 brakes locked. DeHavland Caribou's and Twin Otter's will get moving too.

Posted: 11/16/2018 9:37:12 AM EDT

[#10]

Our G-IV is almost 14,000 lbs per side. 75k MTOW.

Posted: 11/16/2018 12:41:00 PM EDT

[#11]

Of course airlines with use only the power needed to meet the Balanced Field Length, so a takeoff at full power is rare...

Posted: 11/16/2018 2:52:02 PM EDT

[#12]

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Quoted:
Has a engine engineer tell me that idle for a jet is about 80% thrust. So full throttle only adds the last 20%. Not saying this answers your question but just food for thought.

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Idle thrust is nowhere near 80% of the maximum thrust - it may be 80% of the engine SPEED (rotational speed) however.

Just about any aircraft's brakes will be able to hold it in place under full thrust, at least if the aircraft is anywhere near its maximum weight. If nearly empty, then maybe the tires would skid on a dry, good condition surface (23 RCR is considered to be dry and uncontaminated, iirc). Some figher aircraft may be light enough to skid the tires, especially if using afterburner.

Mike

Posted: 11/16/2018 3:06:43 PM EDT

[#13]

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Quoted:
Has a engine engineer tell me that idle for a jet is about 80% thrust. So full throttle only adds the last 20%. Not saying this answers your question but just food for thought.

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Ground idle is ~25%.
In-flight idle is usually 45-50%

2 and 3 spool engines will have the spools at different RPM's depending on speed.

Little light reading for you:
http://www.dj-airways.com/2-spool-vs-3-spool/

3-spool turbofan, each compressor/turbine set spins at a different RPM, independently, unless they are geared together, which is not common practice.

Posted: 11/16/2018 3:11:24 PM EDT

[#14]

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Idle thrust is nowhere near 80% of the maximum thrust - it may be 80% of the engine SPEED (rotational speed) however.

Just about any aircraft's brakes will be able to hold it in place under full thrust, at least if the aircraft is anywhere near its maximum weight. If nearly empty, then maybe the tires would skid on a dry, good condition surface (23 RCR is considered to be dry and uncontaminated, iirc). Some figher aircraft may be light enough to skid the tires, especially if using afterburner.

Mike

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Quoted:
Has a engine engineer tell me that idle for a jet is about 80% thrust. So full throttle only adds the last 20%. Not saying this answers your question but just food for thought.

Idle thrust is nowhere near 80% of the maximum thrust - it may be 80% of the engine SPEED (rotational speed) however.

Just about any aircraft's brakes will be able to hold it in place under full thrust, at least if the aircraft is anywhere near its maximum weight. If nearly empty, then maybe the tires would skid on a dry, good condition surface (23 RCR is considered to be dry and uncontaminated, iirc). Some figher aircraft may be light enough to skid the tires, especially if using afterburner.

Mike

After i saw the first response to my post i was going to respond with this....that he may have been referring to rpm or some other measure when he made the statement.

Posted: 11/16/2018 10:54:52 PM EDT

[#15]

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Our G-IV is almost 14,000 lbs per side. 75k MTOW.

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So 28k thrust vs 75k lbs weight but it's on wheels. If the wheels didn't roll, can I then assume there is no way the engines have enough juice to move the plane?
Are military aircraft the only ones where engine thrust exceeds weight of the aircraft? I am guessing this is what allows an unlimited vertical climb?

<- obviously not a pilot or enthusiast, just a guy who occasionally wonders about such things.

Posted: 11/17/2018 4:12:21 AM EDT

[#16]

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So 28k thrust vs 75k lbs weight but it's on wheels. If the wheels didn't roll, can I then assume there is no way the engines have enough juice to move the plane?
Are military aircraft the only ones where engine thrust exceeds weight of the aircraft? I am guessing this is what allows an unlimited vertical climb?

<- obviously not a pilot or enthusiast, just a guy who occasionally wonders about such things.

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Have you ever pushed a car by hand?

"Pounds of thrust" isn't really a number that gets used day to day, just like the horsepower your car's engine can produce. It is a nice figure to put on a list of specifications. Have you ever seen a horsepower gauge on the dashboard of a car or truck? I never have. I've seen my share of speedometers and tachometers though.

There are a lot of factors that come into play. What are the atmospheric conditions? Hot and humid or cold and dry? Is the engine operating at sea level or 30,000'?

Posted: 11/17/2018 7:40:48 PM EDT

[#17]

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My Learjet produces 3500# of thrust per engine. Above 75% power I have to stand on the brakes hard enough to almost lift me off my seat. Above 90% power my brakes won’t hold the plane.

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I flew a 24d that had 12500 mgtow with just shy of 6,000 lbs thrust. The brakes would not hold hold it at takeoff power, it had 10000fpm vertical speed indicators because it needed 10000fpm vertical speed indicators. It was the most fun I ever had with my pants still on.

Posted: 11/17/2018 8:23:29 PM EDT

[#18]

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I flew a 24d that had 12500 mgtow with just shy of 6,000 lbs thrust. The brakes would not hold hold it at takeoff power, it had 10000fpm vertical speed indicators because it needed 10000fpm vertical speed indicators. It was the most fun I ever had with my pants still on.

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I've only got about 10 hours in the 20 series, I love those little rockets!

Posted: 11/17/2018 8:44:13 PM EDT

[#19]

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I've only got about 10 hours in the 20 series, I love those little rockets!

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I flew a 24d that had 12500 mgtow with just shy of 6,000 lbs thrust. The brakes would not hold hold it at takeoff power, it had 10000fpm vertical speed indicators because it needed 10000fpm vertical speed indicators. It was the most fun I ever had with my pants still on.

I've only got about 10 hours in the 20 series, I love those little rockets!

I flew them for years, was very sad when they went away.....of course 350 gallons the first hour had a lot to do with that...and the awesomness of 121Db at takeoff power

Posted: 11/17/2018 8:44:29 PM EDT

[#20]

An F-15 with GE engines has roughly 30,000 lbs of thrust x2. With 10,000 lbs of gas you get an airplane that weighs 42,000 lbs in 'A' configuration (slick).

Yes it has the capability to drag the tires and jump chocks if you run both engines up high enough without the tailhook used to hold it down. It's fucking awesome sitting on top of that much power that feels like it will get away from you a any second.

Posted: 11/17/2018 8:46:06 PM EDT

[#21]

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An F-15 with GE engines has roughly 30,000 lbs of thrust x2. With 10,000 lbs of gas you get an airplane that weighs 42,000 lbs in 'A' configuration (slick).

Yes it has the capability to drag the tires and jump chocks if you run both engines up high enough without the tailhook used to hold it down. It's fucking awesome sitting on top of that much power that feels like it will get away from you a any second.

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Jeebus, should have gone military

Posted: 11/17/2018 9:04:39 PM EDT

[#22]

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An F-15 with GE engines has roughly 30,000 lbs of thrust x2. With 10,000 lbs of gas you get an airplane that weighs 42,000 lbs in 'A' configuration (slick).

Yes it has the capability to drag the tires and jump chocks if you run both engines up high enough without the tailhook used to hold it down. It's fucking awesome sitting on top of that much power that feels like it will get away from you a any second.

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Once...just once.

Posted: 11/17/2018 10:56:56 PM EDT

[#23]

Harriers, and I think they are still doing the same in the F-35B, on takeoff roll on the boat skid the tires prior to brake release. It will blow the tires if you keep the brakes on and keep on going. I suspect all fighters will do this. Just need enough trust to overcome the friction. But if you throw in a treadmill laws of physics no longer apply.

Posted: 11/17/2018 11:20:39 PM EDT

[#24]

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Harriers, and I think they are still doing the same in the F-35B, on takeoff roll on the boat skid the tires prior to brake release. It will blow the tires if you keep the brakes on and keep on going. I suspect all fighters will do this. Just need enough trust to overcome the friction. But if you throw in a treadmill laws of physics no longer apply.

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On the AV-8A Harriers, they skid the tires because of nozzle position making the aircraft light when higher thrust was commanded.

One of the things we had to worry about when doing low-power 30-30 engine run-ups (30% and 30* nozzles) to ground check a new AMSU, was leaping the chocks if a tie-down chain broke free.

High-power runs were done with tie down chains that befit the USS Nimitz' anchor and special tie down rigging- which was a bitch to install

Posted: 11/19/2018 7:37:22 PM EDT

[#25]

The GE90s on the 777-300 I used to fly had 115,000lbs of thrust each. I have no doubt they could slide a lightly loaded plane even with the brakes set.

Interesting to see a fuel flow over 30,000 pounds per hour per side on takeoff. Even more impressive is if you had a full tank of gas, even at 60,000pph you could sit like that for 5hrs before running dry.

What a machine.

Posted: 11/19/2018 8:18:59 PM EDT

[#26]

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The GE90s on the 777-300 I used to fly had 115,000lbs of thrust each. I have no doubt they could slide a lightly loaded plane even with the brakes set.

Interesting to see a fuel flow over 30,000 pounds per hour per side on takeoff. Even more impressive is if you had a full tank of gas, even at 60,000pph you could sit like that for 5hrs before running dry.

What a machine.

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Damn! That's a lotta dead dinosaurs!

Posted: 11/19/2018 11:20:25 PM EDT

[#27]

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Our G-IV is almost 14,000 lbs per side. 75k MTOW.

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And lightly loaded you can have the same power to weight ratio as an F15

Posted: 11/23/2018 9:57:47 AM EDT

[#28]

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So 28k thrust vs 75k lbs weight but it's on wheels. If the wheels didn't roll, can I then assume there is no way the engines have enough juice to move the plane?
Are military aircraft the only ones where engine thrust exceeds weight of the aircraft? I am guessing this is what allows an unlimited vertical climb?

<- obviously not a pilot or enthusiast, just a guy who occasionally wonders about such things.

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The only aircraft that have more thrust than weight are fighter jets and some civilian aerobatic aircraft. Yep, really you only need that to accelerate in a straight vertical climb. But a high performance aircraft with a sub-1:1 ratio can still climb vertically if they have the speed, they'll just have to stop sometime.

Thrust/weight mainly affects climb performance/acceleration so you don't really need high ratios in airliners, GA aircraft, etc. Some aircraft have ratio's of 1:5 or less and fly fine.

Posted: 11/23/2018 11:24:59 AM EDT

[#29]

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The only aircraft that have more thrust than weight are fighter jets and some civilian aerobatic aircraft.

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And every helicopter ever made.

Also, more thrust than weight doesn't mean an airplane can accelerate or even maintain a constant airspeed in a vertical climb. In order to do that you need more thrust than the sum of weight and drag added together.

Posted: 11/23/2018 12:12:23 PM EDT

[#30]

My bird produces just north of 61,000lbs of thirst per engine, we’ve got three of them.

Posted: 11/23/2018 2:12:29 PM EDT

[#31]

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And every helicopter ever made.

Also, more thrust than weight doesn't mean an airplane can accelerate or even maintain a constant airspeed in a vertical climb. In order to do that you need more thrust than the sum of weight and drag added together.

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OK fair, should have said airplane. And yeah, but there's no quick and easy way to find the drag of a plane like there is for thrust and weight. Suffices for a quick and dirty estimate of performance

Posted: 11/23/2018 3:40:18 PM EDT

[#32]

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My bird produces just north of 61,000lbs of thirst per engine, we’ve got three of them.

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MD11?

Posted: 11/23/2018 3:42:29 PM EDT

[#33]

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MD11?

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My bird produces just north of 61,000lbs of thirst per engine, we’ve got three of them.

MD11?

Yessir

Posted: 11/23/2018 7:29:08 PM EDT

[#34]

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Yessir

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Damn shame those ain't made anymore. I always enjoyed flying on them and the DC-10.

Posted: 11/23/2018 7:50:54 PM EDT

[#35]

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Damn shame those ain't made anymore. I always enjoyed flying on them and the DC-10.

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Yessir

Damn shame those ain't made anymore. I always enjoyed flying on them and the DC-10.

I love flying them, it’s a damn cool airplane. The first takeoff I ever did in it we were empty and she climbed like a raped ape.

Posted: 11/24/2018 6:47:21 AM EDT

[#36]

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And every helicopter ever made.

Also, more thrust than weight doesn't mean an airplane can accelerate or even maintain a constant airspeed in a vertical climb. In order to do that you need more thrust than the sum of weight and drag added together.

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I think you talking lift as far as the helicopter goes, L/D, thrust is propulsion.

Posted: 11/24/2018 6:42:07 PM EDT

[#37]

My current corporate jet has 4000lbs/thrust per side, and an empty weight of about 12,000 lbs (20,000 lbs MGTOW). When we do MX engine runs, the brakes will hold without skidding tires, but only on dry pavement. If the tarmac is wet, no way.

We do static takeoffs from short strips (4000’) so that we preserve AFM runway performance numbers. That last 10% of power setting definitely feels like it’s barely holding.

Posted: 11/25/2018 12:50:26 AM EDT

[#38]

Current jet (PC-24) has 3,420# per side. The plane is built for its short field capabilities so we practice static takeoffs regularly. Great brakes that are easy to apply without having to stand on them and feel like they easily handle full power. Once we let go she's a little rocket ship.

Posted: 11/27/2018 11:02:42 PM EDT

[#39]

My dad worked for GE back in the day. He worked F-104's when they set the climb to altitude record. He said they placed a big water tank on the end of the runway, filled it, and chained the tail of the F-104 to it with a squib bolt. Then they ran it up, and blew the bolt.

Going flying tomorrow in my Champ. Looking forward to dragging my tires in the snow covered grass, with 65 raging horses.

Posted: 11/27/2018 11:39:03 PM EDT

[#40]

I actually found a picture. Looks like it was a water truck, rather than a tank.

https://www.thisdayinaviation.com/tag/world-record-for-time-to-altitude/

13 December 1958: First Lieutenant Einar Knute Enevoldson, U.S. Air Force, set seven Fédération Aéronautique Internationale (FAI) time-to-climb records in a Lockheed F-104A-10-LO Starfighter, serial number 56-762,¹ at Naval Air Station Point Mugu (NTD) (located on the shore of southern California), including Sea Level to 3,000 meters (9,843 feet) in 41.85 seconds; 6,000 meters (19,685 feet) in 58.41 seconds; 9,000 meters (29,528 feet) in 1 minute, 21.14 seconds; 12,000 meters (39,370 feet) in 1 minute, 39.90 seconds; 15,000 meters (49,213 feet) in 2 minutes, 11.1 seconds; 20,000 meters (65,617 feet) in 3 minutes, 42.99 seconds; and 25,000 meters (82,021 feet) in 4 minutes, 26.03 seconds.

Posted: 11/28/2018 12:00:14 AM EDT

[#41]

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I actually found a picture. Looks like it was a water truck, rather than a tank.

https://www.thisdayinaviation.com/tag/world-record-for-time-to-altitude/

https://i.imgur.com/81gsMCo.jpg

13 December 1958: First Lieutenant Einar Knute Enevoldson, U.S. Air Force, set seven Fédération Aéronautique Internationale (FAI) time-to-climb records in a Lockheed F-104A-10-LO Starfighter, serial number 56-762,¹ at Naval Air Station Point Mugu (NTD) (located on the shore of southern California), including Sea Level to 3,000 meters (9,843 feet) in 41.85 seconds; 6,000 meters (19,685 feet) in 58.41 seconds; 9,000 meters (29,528 feet) in 1 minute, 21.14 seconds; 12,000 meters (39,370 feet) in 1 minute, 39.90 seconds; 15,000 meters (49,213 feet) in 2 minutes, 11.1 seconds; 20,000 meters (65,617 feet) in 3 minutes, 42.99 seconds; and 25,000 meters (82,021 feet) in 4 minutes, 26.03 seconds.

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Sweet Jesus!

Posted: 11/28/2018 12:16:47 AM EDT

[#42]

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Sweet Jesus!

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I just did the math for 3000-6000 meters. I got 35,659 FPM

ETA: According to Wikipedia, F-104 (G) 14,000# Empty weight, 15,600# Thrust, with AB

Posted: 11/28/2018 10:09:51 AM EDT

[#43]

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I actually found a picture. Looks like it was a water truck, rather than a tank.

https://www.thisdayinaviation.com/tag/world-record-for-time-to-altitude/

https://i.imgur.com/81gsMCo.jpg

13 December 1958: First Lieutenant Einar Knute Enevoldson, U.S. Air Force, set seven Fédération Aéronautique Internationale (FAI) time-to-climb records in a Lockheed F-104A-10-LO Starfighter, serial number 56-762,¹ at Naval Air Station Point Mugu (NTD) (located on the shore of southern California), including Sea Level to 3,000 meters (9,843 feet) in 41.85 seconds; 6,000 meters (19,685 feet) in 58.41 seconds; 9,000 meters (29,528 feet) in 1 minute, 21.14 seconds; 12,000 meters (39,370 feet) in 1 minute, 39.90 seconds; 15,000 meters (49,213 feet) in 2 minutes, 11.1 seconds; 20,000 meters (65,617 feet) in 3 minutes, 42.99 seconds; and 25,000 meters (82,021 feet) in 4 minutes, 26.03 seconds.

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Bet his chiropractor got a new boat out of the deal!

Thats awesome

Posted: 11/29/2018 12:01:29 PM EDT

[#44]

In 1946, a “time to climb” record was set by an F8F, which, after a take-off run of only 115 feet, reached 10,000 feet in 94 seconds! Although it never saw combat with U.S. forces, the French used the Bearcat during their war in Indochina.

Posted: 11/30/2018 1:10:26 PM EDT

[#45]

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I just did the math for 3000-6000 meters. I got 35,659 FPM

ETA: According to Wikipedia, F-104 (G) 14,000# Empty weight, 15,600# Thrust, with AB

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I just did the math for 3000-6000 meters. I got 35,659 FPM

ETA: According to Wikipedia, F-104 (G) 14,000# Empty weight, 15,600# Thrust, with AB

The Streak Eagle was even better:
3000-6000 meters in just 9.53 seconds. That's 1,038 ft/s, or 62000+ ft/min

Couple interesting tidbits from here:

To lessen even more weight for the attempts, only enough fuel to complete each flight was on board. With less fuel and by eliminating unnecessary or redundant equipment, the aircraft thrust to weight ratio neared 2 to 1.

January 16, 1975, was historic, as records for the first five altitudes fell in the space of six hours, with the three in the middle all occurring on the same flight. On the first record flight, the "Streak Eagle" was flown to the 3,000 meter height in 27.57 seconds, eclipsing the old mark by a margin of 6.9 seconds.

The 6,000 meter record of 39.33 seconds (by a margin of 9.5 seconds); 9,000 meters in 48.86 seconds (by a margin of 12.8 seconds); and 12,000 meters in 59.38 seconds (by a margin of 17.7 seconds), were all set on the same flight. Maj. MacFarlane flew this record flight. "He lifted off in the blink of an eye, level accelerated just a few feet off the ground, pulled up into a vertical climb and accelerated through the speed of sound easily while in the vertical climb,"

For the record attempts at 15,000 meters and above, pilots wore high-altitude pressure suits. At these higher altitudes, the Streak Eagle was 10 seconds faster to altitude than the Apollo Saturn Rocket moon shots.

The Streak Eagle reached 30,000 meters in just 207.8 seconds from brake release - an average VVI of 28,585 ft/min.

Acceleration was made to Mach 2.2 and the optimum climb angle was approximately 55 degrees. The maximum altitude reached was approximately 103,000 feet as the aircraft "coasted" above the record. The engines were flamed out at this altitude, but were restarted inflight.

Posted: 11/30/2018 4:36:06 PM EDT

[#46]

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The Streak Eagle was even better:
3000-6000 meters in just 9.53 seconds. That's 1,038 ft/s, or 62000+ ft/min

Couple interesting tidbits from here:

The Streak Eagle reached 30,000 meters in just 207.8 seconds from brake release - an average VVI of 28,585 ft/min.