Possible bad copy of FEF3???

[FourEightFour]

The reason there is no difference at the low speeds is because you guys have not increased your piston speed enough to out pace the throttle setting to actually matter.


Edit: 765 going only 11 on Horseshoe sound more like a track/traffic/crew limitation vs. a limit of the Berk. By a long shot.

[mikeg1250]

The reason there is no difference at the low speeds is because you guys have not increased your piston speed enough to out pace the throttle setting to actually matter.


Edit: 765 going only 11 on Horseshoe sound more like a track/traffic/crew limitation vs. a limit of the Berk. By a long shot.

I was there and can assure you she was giving it all she had!

http://youtu.be/j4bGc3UsMpg

This is from Rich Melvin....the gentleman who was running the 765 during its 2012 assault on Allegheny Mountain and who has served as one of her primary engineers since 1985:

Steam Locomotive (is) a constant torque, variable horsepower machine.

A steam locomotive does not have tremendous starting torque (tractive effort) like a diesel. However, the torque that it does have remains constant as the speed increases. If the torque is remaining constant as the speed is increasing, that means the horsepower is also increasing as the speed goes higher. This is why it is said that if a steam locomotive can get the train started, it can pull it at speed.
...

To put this in everyday context, when we pulled the New River Trains on the former C&O with the 765, we regularly pulled 34 car trains on that route at speeds up to 70 mph. The ruling grade on that route is only .48%. This year, on the 1.7% grade at Horseshoe Curve, we could only maintain 11 mph with the equivalent load of about 18 cars. Grades make a HUGE difference.

The 765 has a high tractive effort than the 844 ( 64,135 vs 63,750 lbf) and larger cylinders (25 x 34 vs 25 x32) coupled with smaller drives. Long story short, the 765 would be able to pull a heavy consist but given the same lighter consist, 844 would be able to pull it at higher speeds.

Mike may be able to shed more light on this, but I think the part of the simulation we may be missing (or can't be properly simulated) is the multiple front end throttle. A multiple front end throttle (found on most if not all superheated steam locomotive) is a larger manifold with a rolling cam that opens different valves in the manifold as the throttle is increased. At a low throttle setting, only one of the valves would be open allowing a relatively small about of steam to enter the steam chest. While give the proper valve setting (cut off setting) enough steam could be introduced to allow the locomotive to move, given the rate of expansion need to fill the steam chest, the pressure in the steam chest would never be able to equal the boiler pressure and with each piston stroke would be quickly utilized and exhausted. As the engine begins to accelerate, the steam is used faster and faster with each piston stroke and thus more steam must be admitted to the cylinders. Pull back back on the throttle and another valve opens in the manifold.

Again, as the engine accelerates, adjustments must be made to both continue to accelerate and maintain operational efficiency. This is where the power reverse or cut-off comes into play. Remember, the back pressure we have been talking about is just that; pressure pushing back on the piston. As more power (steam) is introduced into the cylinder, the back pressure will climb and thus the engine will actually work against itself. Adjustments are made to the power reverse to begin to "hook up" the engine; reducing the back pressure by adjusting the valve setting. Depending on cylinder and valve sizes, different engines will have different "sweet spots" as far as back pressure in concerned. Typically, a good rule of thumb would be to work about 10% of the cylinder (steam chest) pressure as back pressure (e.g. 150 lbs of cylinder pressure and about 15 lbs of back pressure). Too much back pressure and the the locomotive will work against itself wasting steam and stop accelerating. Too little back pressure means that too little steam pressure is being introduced to maintain the same pulling power. As a result, the engine will begin to decelerate even though steam is still being admitted to the cylinders.

While the back pressure will rise and fall at slow speeds with each exhaust beat, the engine should never work negative back pressure (less than zero)! This can result in serious damage to the cylinders.

[FourEightFour]

I have to heavily disagree on that the consist weighs 18 cars. I count an auxiliary water car that weighs probably 2 light weight coaches, a dead diesel that weighs just the same, if not more. A tool car which is also on the heavy side, 13 revenue cars, and 4 loads of coal. That train probably equals more in the range of 21 - 25 lightweight cars empty. I do not know how much weight is added when passengers board the train in the simulation, so I figure everything as light. The thing that is missing from the simulation, amongst a long list, is curve drag. I have a feeling that horseshoe is pretty rough on the flanges. The Cole formula states that for every ton there is 8 lbs of rolling resistance, for every grade percentage there is 20 lbs per ton of resistance, and for curves there is .8 lbs of resistance per ton per degree of curvature.

On an the type of front end 844 has, the pilot valve lifts first, then numbers two and four lift at the same time, then number three lifts. At least that's the way the one I helped rebuild two months ago worked.

Also it's not really THAT damaging if the engine has negative back pressure. When going down a 4% grade light I have to alternate every mile or so running some back pressure and using the independent to keep the tires cool. Otherwise I have a tire sideways and a very po'd superintendent. But keep in mind this is something you only do light.

[mrennie]

Mike may be able to shed more light on this, but I think the part of the simulation we may be missing (or can't be properly simulated) is the multiple front end throttle. A multiple front end throttle (found on most if not all superheated steam locomotive) is a larger manifold with a rolling cam that opens different valves in the manifold as the throttle is increased. At a low throttle setting, only one of the valves would be open allowing a relatively small about of steam to enter the steam chest. While give the proper valve setting (cut off setting) enough steam could be introduced to allow the locomotive to move, given the rate of expansion need to fill the steam chest, the pressure in the steam chest would never be able to equal the boiler pressure and with each piston stroke would be quickly utilized and exhausted. As the engine begins to accelerate, the steam is used faster and faster with each piston stroke and thus more steam must be admitted to the cylinders. Pull back back on the throttle and another valve opens in the manifold.

That's right - in the Advanced version, I could actually simulate the multiple throttle valves, as I already have some scripting that calculates the value for the core code controller called "regulator" (which is what you see in the HUDs) from the position of the throttle lever in the cab and the prevailing conditions (such as reducing it for condensation and the wire-drawing effect at speed). All I'd have to do is to replace the linear transformation of the throttle lever position into a more elegant equation that takes into account the multiple ports and their sizes.

In fact, what I was told recently, by someone associated closely with the real 844, is this:

The multiple stage front end throttle is just as it sounds, it has multiple throttle valves that open as you open the throttle. In the case of the 844, it has a pilot (smaller) valve, then the main valves that open in succession as the throttle is opened until all valves are fully open. One would assume that all of this happens in a very smooth and even and equal way. The reality is: When you open the throttle, you actually feel the pilot valve open. When you open the throttle more, you actually feel the first valve catch and open. When you get to half throttle, not much happens between 1/2 and 3/4 and then you get the final lift of the valves from 3/4 to full open.

I didn't have a chance to do that before the release, or for the first patch (which I think is still in QA testing , by the way), but I'd like to do it for a second patch.

One more thing - all of this can be done for the Advanced version, but not for the HUD versions . That's because in the HUD versions, "regulator" is the throttle lever position (there's no fancy scripting in between) in order for the throttle to be controllable using the F4 HUD and the Xbox controller.

[mikeg1250]

Mike may be able to shed more light on this, but I think the part of the simulation we may be missing (or can't be properly simulated) is the multiple front end throttle. A multiple front end throttle (found on most if not all superheated steam locomotive) is a larger manifold with a rolling cam that opens different valves in the manifold as the throttle is increased. At a low throttle setting, only one of the valves would be open allowing a relatively small about of steam to enter the steam chest. While give the proper valve setting (cut off setting) enough steam could be introduced to allow the locomotive to move, given the rate of expansion need to fill the steam chest, the pressure in the steam chest would never be able to equal the boiler pressure and with each piston stroke would be quickly utilized and exhausted. As the engine begins to accelerate, the steam is used faster and faster with each piston stroke and thus more steam must be admitted to the cylinders. Pull back back on the throttle and another valve opens in the manifold.

That's right - in the Advanced version, I could actually simulate the multiple throttle valves, as I already have some scripting that calculates the value for the core code controller called "regulator" (which is what you see in the HUDs) from the position of the throttle lever in the cab and the prevailing conditions (such as reducing it for condensation and the wire-drawing effect at speed). All I'd have to do is to replace the linear transformation of the throttle lever position into a more elegant equation that takes into account the multiple ports and their sizes.

In fact, what I was told recently, by someone associated closely with the real 844, is this:

The multiple stage front end throttle is just as it sounds, it has multiple throttle valves that open as you open the throttle. In the case of the 844, it has a pilot (smaller) valve, then the main valves that open in succession as the throttle is opened until all valves are fully open. One would assume that all of this happens in a very smooth and even and equal way. The reality is: When you open the throttle, you actually feel the pilot valve open. When you open the throttle more, you actually feel the first valve catch and open. When you get to half throttle, not much happens between 1/2 and 3/4 and then you get the final lift of the valves from 3/4 to full open.

I didn't have a chance to do that before the release, or for the first patch (which I think is still in QA testing , by the way), but I'd like to do it for a second patch.

One more thing - all of this can be done for the Advanced version, but not for the HUD versions . That's because in the HUD versions, "regulator" is the throttle lever position (there's no fancy scripting in between) in order for the throttle to be controllable using the F4 HUD and the Xbox controller.

NOW WE'RE TALKING!!!! Do you think you will be able to release this in a patch at some point? Sound awesome!!

BTW: has the fist patch you talked about been released yet?

[buzz456]

Read about five lines above on your post.

"I didn't have a chance to do that before the release, or for the first patch (which I think is still in QA testing , by the way), but I'd like to do it for a second patch."

[mrennie]

Read about five lines above on your post.

"I didn't have a chance to do that before the release, or for the first patch (which I think is still in QA testing , by the way), but I'd like to do it for a second patch."

Yep, they've only had the patches for two and a half weeks (which is still a lot longer than it took me to make them).