Engine Question.

guido · Jan 6, 2009

Hello guys and gals,
I have a question about engine speed droop.
What is it?
Guido.

thurlow · Jan 6, 2009

The Soviet supersonic airliner had a droop, but I think it was just the cockpit; the engines appear to be in the wings. :>)

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JDemaris · Jan 6, 2009

Is this another text-book test question?

Droop, when referring to an engine powering something is usually a reference to governor error.

The term can get much more specific depending on what that engine is powering. Some gensets use the term "frequency" droop.

buickanddeere · Jan 6, 2009

Depends if the speed control/regulation/govenor is a simple "proportinal controled". Or if it's fancier with "Integer" and maybe even "Derivitive" function for full PID control.
Proportional gives about 10% droop from " fast idle" down to "full load" ropms.
Integer will recover back while under load to the initial no load rpm setting.
Derivitive will overshoot the throttle when subjected to sudden load changes. To provent bogging or over reving.

pete black · Jan 6, 2009

no it not what happens to you as you age. for large synchonous generators controlled by hydraulic governors speed droop is a mechanical damping introduced into the govenor system to enable the generators to operate in parallel without fighting each other. this is a dialed in setting and typically set at 5%. for a system that has automatic frequency control, if or when, an electrical system's speed (frequency) decreases/increases, each generator tied to that system will see the speed change and respond smoothly and evenly to return the frequency back to normal. so, in this application, an introduced speed droop prevents one generator from reacting first and excessively. i recognize that this explanation pertains to generators and not tractors, but somewhat explains what speed droop is.

Glen D Anderson · Jan 6, 2009

Speed droop: The difference between engine speed at maximum high idle and the engine speed at maximum full load. A method of rating the operating characterisitcs of the engine governor, be it a mechanical style or programming of the governor feature in the engine ECM...........

Engines used in power generation or stationary applications typically utilize a governor or ECM programming that has less "speed droop" in order to maintain more precise engine speed control.........i.e. Max. high idle - 1850 RPM., Max. full load - 1800 RPM., speed droop = 50 RPM............

Engines utilitzed in highway/vehicle applications typically utilize a governor or ECM programming with more "speed droop" in order to provide better driveabilty for the vehicle............i.e. Max. high idle - 2300 RPM., Max. full load - 2150 RPM., speed droop = 150 RPM................

Next?

guido · Jan 6, 2009

Hello thurlow,
I tink you are right about the cockpit,
not the droop I was looking for.
I have not seen the right answer so far!
Nice looking bird! maybe we should call it DROOPY......chuckle.
Guido.

Dick L · Jan 6, 2009

The drop of RPM's from when load is applied until the governor kicks in. That is if you are on tractors? The meaning changes some what as you change applications.

thurlow · Jan 6, 2009

Actually, it wasn't designed like that; when the plans got to the shop floor, they'd been stuffed inside someone's coat to keep them dry and there was a fold right behind the cockpit. The builders were afraid to quesion the design bureau...............

guido · Jan 6, 2009

Hello Dick L,
This is tractor talk. I would not ask a question that is out of context or deceiving. That is not my intent.
The question was asked as a challenge.
Guido.

DickL · Jan 6, 2009

A little short tempered huh?

An answer that is for other applications on Tractor talk would not mean the answer was totally wrong. Only slightly off the mark that you were trying to get.

Should have been a question over on the Tractor Pulling Board. Droop would be something that they need to be aware of. Some of those boys over there would be very pleased for the edjamacation.

Anonymous-0 · Jan 6, 2009

This is not a Soviet plane, it is a British Concorde, the only supersonic passenger airliner, one of it flights was London England to New York in less then 2 and 1/2 hours, it flew for 30 years, with only one accident, a Great airplane.

Glen D Anderson · Jan 7, 2009

For anyone that's curious, here's a link that has a good explanation of speed droop:

http://www.toromontcat.com/powersystems/pdf/ConsultantsCorner/Engine%20Speed%20Governors.pdf

Although the application is somewhat geared towards power generation, the definition still applies to all governed engines............

pete black · Jan 7, 2009

interesting what can be discussed here, anything from cow poop to speed droop!

Glen D Anderson · Jan 7, 2009

No, it's not a Concorde.

It IS a Soviet plane, the Tupolev Tu-144............

guido · Jan 7, 2009

Droop speed is what Mr. anderson said. The difference between wide open throttle at no load, and wide open throttle at full load.
The answer has to do with "GOVERNOR DROOP" or how "sensitive" the governor assembly is to an engine speed change. How much speed will be lost depends on the governor rection. There is a formula that can be applied to determine engine % of speed droop.
DROOP = MNL - MFL / MFL x 100%.
Here is an example of an engine with the max no load speed of 2250 RPM'S. and a full load speed of 2100 RPM'S.
2250 - 2100 = 150 / 2100 = 0.0714285 x 100 = 7.14%.
The link provided by Mr. Anderson will provide I'M sure more info that I can possibly muster.
On engine driving gen sets it is critical to keep the rpm's at zero droop, IN ODER TO PRODUCE 60HZ POWER, those kinds of governors will keep the engine running at the same RPM'S regardless of load.
They are called ISOCHRONOUS GOVERNORS.
Guido.

guido · Jan 7, 2009

Hello DickL.
If i can get only one response like yours then my time was not waisted.
I may post the question on the pulling board, they are always talking about governor weights and such.My aim is to challenge, and motivate interaction.
Guido.

buicanddeere · Jan 7, 2009

The Soviet flop of a copy from stolen Concord plans is a source of amusement to this day inside the intelligence community.
The Soviets noted for stealing technical plans were known to be snooping for copies of the Concord rather than spend the time and money to develop their own SS airliner.
Much similar to how the Soviets stole the plans for nuclear warheads, the F-15, F18, space shuttle etc.
Anyways the Brits equipped with a set of doctored Concord plans let them get stolen. Unknown to the Soviets the plans had relocated the center of gravity 13 ft.
A few test flights of the now wobbly Concord copy and the thing crashed. Soviets dropped that project.

Engine Question.

guido

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thurlow

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JDemaris

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buickanddeere

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pete black

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Glen D Anderson

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guido

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Dick L

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thurlow

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guido

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DickL

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Anonymous-0

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Glen D Anderson

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pete black

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Glen D Anderson

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guido

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guido

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buicanddeere

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