Talk:Thrust

Rocket boosters

Are we sure that we got the space shuttle thing right? Holly goosh. Thrust is for babies. Because it seems to only have an acceleration of 7.2 m/s^2. Thats kind of slow isn't it? Even though one minute later it will be going at 1500km/h, but that would take a minute! Surely space shuttles accelerate faster than that. Pseudoanonymous 23:11, 15 May 2006 (UTC)

Information on Thrust

I have been listening to an exchange about what thrust is. The technical definitions do not help, so is thrust the force of the gases pushed through a jet engine and out the exhaust, or is it the force of the gases against the front of the engine.

An explanation would be greatly appreciated as soon as possible. (Its getting pretty heated here)

Thanks in advance for anyone's response or everyone's!

Cnfusd in MO Fshngoddes 10:31, 25 May 2007 (UTC)

Inaccurate Diagram

The diagram showing lift, weight, thrust and drag is not entirely correct. In UNACCELERATED flight all OPPOSING forces are equal. The diagram shows thrust being greater than drag, thus the aircraft must be accelerating. The article should note this or replace the diagram with an accurate one. Also, a diagram that shows the poper relationship between the 4 forces should show lift and weight being greater than thrust and drag. 163.118.44.134 18:22, 12 June 2007 (UTC)

Wrong scope of the thrust notion

If you begin from disambiguation, you will screen off fictional personages, pop song groups etc. and pick up physics. But inside physics you get straight to fluid dynamics and aircraft. I understand that this is because your fluid dynamics team is in charge. However, thrust forces occur in ground-based machinery, etc., and your article does not cover this matter. I have a question on thrust forces in structural analysis of concrete reinforcement and I failed to get even a definition. Is it just any force perpendicular to a plane? No answer in wiki. —Preceding unsigned comment added by 83.237.5.39 (talk) 09:10, 15 March 2009 (UTC)

Someone please explain 'pounds (lbs) of thrust'

Thrust is regularly quoted in pounds . i.e. A rocket engine has 10,000 lbs of thrust. In layman's terms what does that mean? Does it mean that if the rocket weighed 10,000lbs and the engine was generating 10,000lbs of thrust the rocket (pointed vertically) would not rise off the launch pad? I would love if someone would explain in simple terms the relation between pounds and thrust, with some simple examples like the previous rocket example.--Trounce (talk) 15:52, 13 April 2009 (UTC)

As you know, thrust is a force. In the SI system of units, force is measured in Newtons. In the old Imperial system of units, force is measured in pounds, often abbreviated lbf. See Pound (force). (The pound was also a unit of mass, often abbreviated lbm. See pound (mass).) A force of 1 lbf is equal to approximately 4.448 N. See Weight.

If a rocket weighs 10,000 lbf and it generates a thrust of 10,000 lbf, it will be able to support its weight at the earth's surface but unable to launch itself vertically upward. However, on the surface of the moon it will easily be able to launch itself vertically upward.

$W=mg\;$

where W is weight

m is mass

g is the acceleration due to gravity

Of course, it is essential that W, m and g are expressed in a consistent system of units such as Newtons, kilograms, and meters per second squared.

Under conditions of standard gravity (g₀ = 9.8 m/s² = 32.2 ft/s²) an object of mass M lbm has a weight of M lbf. However, when conditions differ from standard gravity (such as at the poles, or up a mountain, or in orbit around the earth, or on the moon) an object of mass M lbm has a weight different to M lbf.

lbf and lbm are not consistent units with respect to the above equation. When using the Imperial system of units where W is measured in lbf, m is measured in lbm and acceleration a is expressed in feet per second squared, the following equation must be used.

$W=m{\frac {g}{g_{0}}}$

where g is local acceleration due to gravity (in feet/sec²)

g₀ is standard gravity (32.2 ft/sec²) Dolphin51 (talk) 23:49, 13 April 2009 (UTC)

Excellent, Dolphin51 you've sorted it for me! As soon as I read "If a rocket weighs 10,000 lbf" it clicked with me. I was confusing pound force with pound mass with regard to weight. I forgot that weight is a force. For "weight" I normally use kilos, which is a unit of mass and that led me to think pounds of thrust was pounds mass!

Am I right in thinking that in a perfect world we'd use Newtons instead of kilos for weight? (and that would have saved my confusion from that start)--Trounce (talk) 15:15, 22 April 2009 (UTC)

Yes, in a perfect world we would all talk about weight in newtons, and the kilogram would only be used where we were clearly talking about mass. However, old habits die hard and we often talk about weight in kilograms, leading to confusion, particularly among students.

Some authors attempt to make it a little more rational by using the abbreviation kgf to indicate a weight (ie a force). The unit kilopond is no longer in widespread use, but it is the weight of a mass of one kilogram under conditions of standard gravity, and therefore equal to one kgf. Dolphin51 (talk) 23:07, 22 April 2009 (UTC)

Thrust to Power

Hello, I've found the section Thrust to Power too short and succinct for the casual reader, so I wrote a new section explaining the differences between Thrust and Power in a more didactic way. Feel free to review and merge as you see appropriate, and if you guys don't like the rewritten section feel free to remove it. Thank you!--Fbastos7 (talk) 04:34, 10 May 2009 (UTC)