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HFQ Official Snippet #23

This fascinating series is a combination of historical seafaring, swashbuckling adventure, and high technological science-fiction. Join us in a discussion!
Re: HFQ Official Snippet #23
Post by Cartref   » Tue Apr 28, 2015 6:31 pm

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Thank you very much again, for another snipet, despite the demanding schedules.

Cheers & Beers
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Re: HFQ Official Snippet #23
Post by AirTech   » Tue Apr 28, 2015 7:39 pm

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runsforcelery wrote: There was enormous room for improvement in the efficiency of both, since Vyrnyr’s development of pressure dynamics was still at a very early stage, and there were still a few problems with the poppet valves which admitted steam to the cylinders. Despite that, the current design would produce about sixty-one dragonpower (over fifteen hundred Old Earth horsepower) by Owl’s calculations and was probably already on a par with those of the last two decades or so of the nineteenth century.

 


Poppet valves? Who uses poppet valves on a steam engine? Slide valves are much more reliable at the sizes a steam engine requires and much easier to make and seal as you only need to be able to grind and/or scrape a smooth surface not machine a matched thermodynamically stable round one. Unreliability has been a marker of their application on steam systems (internal combustion systems are fundamentally different in this as steam has a water film to lubricate the valve seats where this is absent in internal combustion engines, steam is also very erosive so seats that don't lap themselves, producing significant leakage, requiring frequent maintenance).
The other issue is a poppet valve arrangement requires four valves per cylinder on a double acting cylinder as opposed to a single slide valve and a multi lobe camshaft to drive them, reversing is also painful.
Poppet valves do have the ability to be retimed by cam modification but this is not really an advantage unless you are going to internal combustion - in which case the conventional cylinders driving the wheels is a very bad choice.
(BTW, you can build an internal combustion engine with slide valves (or sleeve valves) but the automotive industry generally does not (a number of aeroengines have, as a lot of motor cycles (most two strokes have a form of slide valve with the cylinder porting))).
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Re: HFQ Official Snippet #23
Post by Captain Igloo   » Tue Apr 28, 2015 8:08 pm

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It was quickly found that slide valves didn't work with superheaters because the lubricants of the day couldn't protect such a great flat sliding valve under pressure (the steam pressure acted upon the valve even with balancing strips) at the superheated temperatures and valve seats were quickly worn and/or scored. In contrast, the steam pressure had no effect on the piston valve; it was completely balanced and it was much more easily lubricated. This factor, plus the port area, doomed the slide valve.

Regarding the use of slide valves on superheated engines, the superheated steam is MUCH hotter than saturated steam. The higher temperatures cause lubricating oil failure i.e it starts to break down by the splitting of the long hydrocarbon chains into shorter chains, These have much less viscosity and diminish the oil film's ability to carry load. Slide valve engines used common lubricating oil; superheated engines had to use oil specifically developed to not break down at the higher steam temperatures.
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Re: HFQ Official Snippet #23
Post by ksandgren   » Tue Apr 28, 2015 9:31 pm

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jeremyr wrote:
peke wrote:

And on a different note, I wonder what's that "other book" our celery-loving poster mentioned?


Doesn't matter, I'll read it. But I'm hoping it's either the next multiverse or safehold story.


Thanks for the snippet, RFC!

It appears the other book mentioned as being submitted two months late is "Road to Hell" in Multiverse
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Re: HFQ Official Snippet #23
Post by n7axw   » Tue Apr 28, 2015 10:13 pm

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Thanks to RFC for a very informative snippet...

I hope that David can see some light at the end of the tunnel with the current pressure on his schedule...and not because I like snippets which I certainly do.

David is no spring chicken and we don't want him crowding so hard he endangers his health.

Don
When any group seeks political power in God's name, both religion and politics are instantly corrupted.
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Re: HFQ Official Snippet #23
Post by n7axw   » Tue Apr 28, 2015 10:46 pm

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Now on to the snippet...

First, the locomotive is interesting, although it seems a bit much to invest too much effort on it before the war is over. But given that conversation Sharleyan had with her advisors back in LAMA, it's not hard to see why she is interested in it.

Moving on, we now know where the the initial issue of M96es and their pistol counterparts went...to BGV! We already had hints of that before. And those who were worried about the ammo supply can feel at least partially vindicated even if our favorate industrialist seems acutely aware of the problem and is moving to rectify the matter.

On a more positive note, we see the EOC diversifying the locations of its industrial plant, in part to Emerald, so that a catrastrophe at one location doesn't completely shut things down.

Finally, the bad guys got more out of their intelligence haul than I expected. It turns out that the primary benefit didn't have to do with steam engines, but with blast furnaces and helping the church umprove their steel production... The question remains, however, if there will be time for the church to fully implement what they have learned before the AOG armies are taken out of play and the alliance closes in.

From the description of what the Dohlarans are up to, it certainly makes good sense to give a very strong priority to isolating Dohlar and knocking her out of the war.

Don
Last edited by n7axw on Tue Apr 28, 2015 10:50 pm, edited 1 time in total.
When any group seeks political power in God's name, both religion and politics are instantly corrupted.
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Re: HFQ Official Snippet #23
Post by pokermind   » Tue Apr 28, 2015 10:48 pm

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A 2-4-0 Columbia type is the first full size locomotive made on Safehold?

Poker
CPO Poker Mind Image and, Mangy Fur the Smart Alick Spacecat.

"Better to be hung for a hexapuma than a housecat," Com. Pang Yau-pau, ART.
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Re: HFQ Official Snippet #23
Post by Annachie   » Tue Apr 28, 2015 11:30 pm

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A Columbia is 2-4-2. But either seems a good place to start. A Bigboy would be a bit much. :)
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You are so going to die. :p ~~~~ runsforcelery
~~~~~~~~~~~~~~~~~~~
still not dead. :)
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Re: HFQ Official Snippet #23
Post by xrayangiodoc   » Wed Apr 29, 2015 2:24 am

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Great snippet! When the next one is suddenly revealed I feel like the lab rat in the Skinner box who has finally received a food pellet after repeatedly pressing the bar. Intermittent reward results in the most difficult to extinguish behaviors.
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Re: HFQ Official Snippet #23
Post by Marty   » Wed Apr 29, 2015 3:06 am

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The shotgun will come in handy during the Safehold Zombie Apocalypse. :mrgreen:
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