HT Rolls to Resist Cold - effects of a critical failure?

[Þorkell]

Originally Posted by DouglasCole

I walked to class for a mile or so in -28F with strong winds. Wind chill in Chicago that day was supposedly -70F.

Uphill, both ways?

[DouglasCole]

Originally Posted by Þorkell

Uphill, both ways?

Well, the Evanston lakefront is about as flat as you'd expect one to be (very), so I will not claim that one.

It was, however, really flippin' cold.

I have since migrated to Minnesota (West Iceland?), and while I've still yet to experience -28F without windchill again, I regularly get doses in the -9 to -20 range.

Down at -20F and below, the vehicles usually quit before the people 'round here.

[Pursuivant]

Originally Posted by Fred Brackin

So rules for what happens to humans fully exposed to 100 mph winds aren't needed.

Unless you're traveling in a vehicle or the equivalent.

One of my areas of interest is historical aerial warfare; the conditions that World War I and World War II aviators faced could be just brutal. The example I gave above (-60 *F & 250 mph winds) is exactly what World War 2 heavy bomber crews faced if they had to fight from open gun positions or if combat damaged opened the interior of their aircraft. (One desperate British flier actually went out on the wing of his aircraft to fight an engine fire, tied to a rope held by his crewmates. He won the Victoria Cross for his actions). Even with multiple layers of winter clothing and heavy electrically-heated suits, frostbite could occur in a matter of seconds.

[Fred Brackin]

Originally Posted by Pursuivant

Unless you're traveling in a vehicle or the equivalent.

.

That looks closer to travelling outside a vehicle.

A complicating factor would be a need to adjust all your numbers for the atmospheric density. That bomber would probably have been flying at 25,000 feet or more. Your character needs oxygen at that height or he might black out even before the cold gets him.

You even need to adjust the rules to reduce the amount the air pushes on you. That lower density would be the only reason that wing-crawling stunt was possible.

Some extraordinary levels of rules complexity would be theoretically possible

[Pursuivant]

Originally Posted by Fred Brackin

That looks closer to traveling outside a vehicle.

Technically, but there were some WW1 and early WW2 aircraft which had crew effectively standing up in a ~60-100 mph slipstream, so it's not unreasonable to have someone exposed to 120 mph winds for hours at a time with perhaps winds up to 250 mph if the airplane is in a dive or facing headwinds. At any TL, air blowing through openings in the aircraft's fuselage (e.g., an open bomb bay) can be quite strong even if it wasn't quite traveling at the same speed as the aircraft.

Originally Posted by Fred Brackin

A complicating factor would be a need to adjust all your numbers for the atmospheric density. That bomber would probably have been flying at 25,000 feet or more. Your character needs oxygen at that height or he might black out even before the cold gets him.

The simple method, which might not be accurate, is to just multiply by air density if it's less than 1 ATM. For example, at 0.5 ATM you're effectively getting half the usual effects of moving air.

Hypoxia at altitude is different from Cold. I've got house rules that deal with that particular problem, but they're not applicable here. Suffice it to say that at altitudes much above 15000 feet you either need long periods of slow adaptation (like mountain climbers use) or else continuous oxygen supplies or else you're incapacitated within 10 seconds, unconscious within 30 seconds, and dead within 2-4 minutes.

Originally Posted by Fred Brackin

Some extraordinary levels of rules complexity would be theoretically possible

Yep. The trick is to do all this with an acceptable balance between playability and accuracy. Where that balance lies depends on your desire for simplicity & speed of play vs. bloody-minded simulation.

[Þorkell]

Originally Posted by Fred Brackin

A complicating factor would be a need to adjust all your numbers for the atmospheric density. That bomber would probably have been flying at 25,000 feet or more. Your character needs oxygen at that height or he might black out even before the cold gets him.

You didn't read that article did you? First paragraph mentions that the crewman started his wingwalk when the plane was at 10,000 feet. A bit down from that it mentions that the bomber got attacked at 13,000 feet.

[Fred Brackin]

Originally Posted by Þorkell

You didn't read that article did you? First paragraph mentions that the crewman started his wingwalk when the plane was at 10,000 feet. A bit down from that it mentions that the bomber got attacked at 13,000 feet.

I had not read it but I have now.

The Interesting thing I got out of it was that the plane was not going at 250 mph but rather only 100 mph. I had expected that the pilot would have slowed to near the stall speed of his aircraft both because of engine damage and to slow the slipstream feeding the fire.

The srticle didn't say that either but it's the logical deduction and it certainly makes wing-crawling more practical.

A quick Google makes air pressure at 10,000 feet c. 10 p.s.i. That would reduce both windchill and wind force to about 2/3rds or c. 65 mph though you do need to take into account the no doubt colder air temp at that altitude. 25,000 feet would be c. 5 p.s.i. and even 250 mph is reduced to c. 80 mph.

As I said very great complexity is possible.

[Pursuivant]

Originally Posted by Þorkell

You didn't read that article did you? First paragraph mentions that the crewman started his wingwalk when the plane was at 10,000 feet. A bit down from that it mentions that the bomber got attacked at 13,000 feet.

In fairness to Mr. Bracklin, the effects of hypoxia can start to show at ~10k feet (~3000 m) if you haven't had much time to adapt (e.g., aircrew taking off from near sea level and climbing relatively quickly to altitude). In particular, early symptoms affect vision and might slightly affect judgment and reflexes.

While the action that won Sgt. Ward his VC took place at lower altitude and speed than normal for most WW2 heavy bombers, it's not out of line for the sort of things that PCs might attempt in a game.

[Fred Brackin]

Originally Posted by Pursuivant

I

While the action that won Sgt. Ward his VC took place at lower altitude and speed than normal for most WW2 heavy bombers, it's not out of line for the sort of things that PCs might attempt in a game.

Also a medium bomber (Wellington) rather than a heavy. Not so far to crawl across the wing.

[Pursuivant]

Originally Posted by Fred Brackin

I had expected that the pilot would have slowed to near the stall speed of his aircraft both because of engine damage and to slow the slipstream feeding the fire.

Paradoxically, sometimes accelerating helped to put out a fire. WW1 pilots were sometimes able to save themselves by diving hard if the engine caught fire. OTOH, more oxygen at lower altitudes might make a fire that had "mostly" self-extinguished at altitude reignite.

Originally Posted by Fred Brackin

A quick Google makes air pressure at 10,000 feet c. 10 p.s.i. That would reduce both windchill and wind force to about 2/3rds or c. 65 mph though you do need to take into account the no doubt colder air temp at that altitude. 25,000 feet would be c. 5 p.s.i. and even 250 mph is reduced to c. 80 mph.

For game purposes, it seems simplest to just divide windchill/wind force by the standard Atmospheric Densities from GURPS Basic. Perhaps:

Very Thin, x0.01
Thin, x0.5
Standard, 1x
Dense, 3x
Very Dense, 10x

To extend the RAW for Cold, perhaps require a roll to avoid Cold every 5 minutes for windspeeds of 60+ mph (vs. every 10 minutes for winds of 30+ mph), 3 minutes for 120+ mph, 2 minutes for 250+ mph, and every minute for 500+ mph.

For example, a heroic airman clinging to an aircraft wing at 10k-feet and traveling at 100 mph would effectively be in Thin atmosphere, with an effective windspeed of just 50 mph, meaning he'd have to roll for Cold every 10 minutes.

I have no idea if these numbers are correct, however.