MORE ON THE BLAST NOZZLE

[Trainman4602]

To add to the current discussion on the blast nozzle I figured that I should make a video.


You can make all the calculations that you wish the bottom line is how well does my locomotive steam.

You can make your own conclusions. I like the bark, how about you?

Here is the link

http://www.youtube.com/watch?v=vWGe_6239EQ


Look forward to more you tubes later on this week.

NJLS FALL MEET

PAUL KURTZ’S MASON BOGGIE

[BryceGTX]

Hi Dave:

I watched your video. I don't see how you proved the 1 in 6 because you did not compare this design to the optimal design. You did not even compare it to a poor design.

You said "I don't see any back pressure". I didn't either because you did not show us an indicator diagram... or a pressure plot of your blast pipe pressure.

You ran all weekend long on 50 pounds of coal. So if it was a poor design would it use 100 pounds? If it was an optimal design, would it use 25 pounds?

You say you do not care about efficiency. However, you argue your brakes use hardly any air (it is efficient in air use).

Then you say you are not sure any of the 1:1 locomotives cared about efficiency.. however, anyone that reads steam locomotive history knows how the railroads and locomotive designers were obsessed with efficiency.

For me, I have no arguement with your design. I would just like to see other ideas. I get your point, you like 1 in 6. However, you have hardly proved it is the most optimal design. Clearly multiple nozzles are more efficient. So why are you arguing?
Bryce

[Harlock]

I have finally gone in and read the entire thread about 1 in 6 and watched all of Dave's videos. Very fascinating stuff from all corners and a lot of information to keep in mind when designing an engine from scratch in the future, or scaling down an engine for which model plans are not already available. It all adds to the confidence of "but will it steam well?" when taking all of this into account.

I think the only thing that Dave is trying to defend is that if you use his method as a rule of thumb, you will end up with an engine that steams well enough to where you don't have to worry about power and is efficient by reasonable standards. As others have said, it is a good rule of thumb. This is quite acceptable for much of the live steam fraternity, which is largely a nuts and bolts crowd without a formal engineering background. When you have an engine that pops off going uphill pulling a full load, you can pretty much call it a day there. Most people are happy at that point.

I think that both sides (scientific vs. practical experience) bring a lot to the table, and that one side can be used to double check the other. For what we are doing with our models and how we are running them, the last 10% just doesn't matter, unless part of your enjoyment of the hobby includes getting every last drop of efficiency out of your design.

On a future project I have in mind, I will likely start at the 1 in 3 / 1 in 6 + bore/7 and see where that ends up, then see if there is any optimizing from there using more precise methods. More research can't hurt, but the bottom line is, you don't have to do that if you don't want to, following Dave's rule of thumb. I think the main debate here has mainly been between 'perfection' and 'good enough'. Dave isn't trying to scientifically prove anything, he's showing you that he has a well running engine using his general guide line, with a tongue-in-cheek attitude to the original thread topic.

--M

[BryceGTX]

the last 10% just doesn't matter

Are you sure we are only talking 10%.....

How do we know it is not 200%

The argument is that this loco steams great. Fine, a 1965 Ford pickup carries 3 bags of potatoes just as well as a 2010 F150. Without any other testing, we would consider them the same.

Problem is, the 1965 Pickup gets 8 mpg... The 2010 gets 20 mpg.

We are in the point of discussion where we do not know if we are getting 10 miles per pound of coal or 50 miles per pound of coal.

Bryce

[Trainman4602]

Hi Bryce

Thanks for the comments. I ask can we see a video of you locomotive running and all the efficiently charts diagrams and so forth. How much fuel you are using to water consumption, dynamometer testing results?


I can tell you that we ran the 1361 all summer long. We ran all three days at the PLS NJLS and WLS both the spring and fall meets plus a number of run days at PLS and we burned eight 50 lbs bags of coal. That was $160.00 worth.

Cheap entertainment. We had fun running not worrying about our efficiency just fun running pulling passengers and listing to the 1361 barking up a grade with a full load.
I can see were this data could be of use in full size practice but for an 1 ½ model, NO.

Can we see your locomotive video and your calculations for efficiency please.

BTW Bryce
Making steam has absolutely nothing to do with stopping your train with air brakes.

Mike

You pretty much hit the nail on the head with you comments.

Most live steamers are just a nuts and bolts gang with no sheep skin to hang up.

If that’s your bag, doing efficiency trials and so on, great. I just enjoy running and listening to the sound of the locomotive working up a grade.

That’s my thing.

[JJG Koopmans]

Great video!

I saw something like a Johnson bar on the loco, was it used or was the run in full gear?
Kind regards
Jos Koopmans

[Trainman4602]

Hi Jos

Thanks for the compliments.

I have a johnson bar ( reversing quadrent) but I don't notch it up.
At most tracks that we run at the stright aways are to short to see the effects of notching up. We usually run in the corner.

[JJG Koopmans]

Hi Dave,
I am very sorry then, but imho your video does not prove anything since my same ho tells me that any front-end will work with too much steam. Expand man!, your engine is fabulous and show it again!
Kind regards
Jos Koopmans

[Fred_V]

come on guys, lighten up.
i don't know why Dave is so set on proving he is right. if he is happy with his setup GREAT. you don't have to prove anything.

for Jos and others, myself included, refining the process is a challenge. i have already seen that adding an arch made a huge improvement in steaming and coal consumption. adding a larger nozzle reduced back pressure and made the engine run noticeably better. what else can be done?

on the other side of the pond they like to have efficiency trials. they don't HAVE to do that; they just enjoy doing it and seeing what they can get out of their engines. over here i don't know of anyone who uses their Johnson bar as it should be used.

[Bill Shields]

That I have avoided this thread...

nothing proved here but hard-headedness and lots of 'letting off of steam'.

[B&OBob]

I enjoyed Dave's video -- it was almost like riding along with him over a track with mildly varying conditions. Whether he intended to make the point or not, he showed that 1:6 is a good starting point. In the case of 1361 it is also a good place to stop and have fun; maybe 5.86:1 or 6.39:1 would be optimum, but so what -- what he has works.

It has been suggested that Dave's assertion is not based on precise comparisons with other design parameters, so it might not be optimum as he claims, and therefore doesn't prove anything. Perhaps to satisfy the doubters there should be a test made with measured amounts of coal and water (including feed water temperature and calorific value of coal); ambient air and exhaust temperatures; exhaust gas analysis; precisely calibrated indicator diagrams; thermocouples everywhere; measurement of developed power with a dynamometer car; and tests repeated with ten different engineers to eliminate operator variations.

How precise do you want to be? As far as the British IMLEC compettions are concerned, I have been to several of them since the first one in 1968 and the best you can say of the results are, efficiency is startling low and it depends as much on the engineman as the locomotive as well as on a good dose of luck on the day of the test.

In short, as someone has already posted, lighten up. This is an emperical hobby, not precise science. As for me, I will still keep a variety of exhaust nozzles in my toolbox and fit the one to my engine that gives the best track performance with the coal being used, an advantage of small scale locomotives where changes produce immediately noticable, if not measurable, results.

Bob

[jessebanning]

It sounds to me a few people would rather ridicule Dave and his "techniques" rather than take what he is offering as a basic "rule of thumb." It is obvious his technique works for him and his locomotives by his videos. He's popping his safeties while working hard. This means he is getting sufficient draft to the fire to make more steam that what he is using. One must remember that we in the "HOBBY" are not prototype railroad operations. We are not hauling long heavy trains over a vast distance. So how is efficient truly determined? If you burn up a 50 lb bag of coal in a hour, obviously something is wrong. This is a hobby and not a railroad operation. If one is that worried about efficiency and cost of operating a steam locomotive, maybe you should look into a diesel and just worry about a few gallons of fuel. Dave is just offering his advise on what works for him. I dont think it is fair to him to bash him and and to try to find flaws in free advise. This is supposed to be a place where one can seek advise and from multiple areas, not a high school court yard where all the he said she said drama takes place. If you don't like he is saying, don't follow it. Use whatever works for you.