Heat

[billvon 2,406]

We did another tunnel camp last weekend at the Eloy tunnel. I was prepared to suffer in the heat there, but it really wasn't that bad. The only session that was really brutal was the last session on Saturday at about 3pm. I think it was about 108F outside. Other than that it was pretty tolerable. Temps ranged from mid-80's to about 104.

I think a big part of it is that when you were on the schedule we had (1 hour in, 1 to 1.5 hours out) you're in the air conditioned part of the tunnel for most of the time, so you get to cool down. Another trick that worked for me was standing in the tunnel as often as possible - the air would change direction and dry the parts of me that were getting really sweaty.

Apparently there is a misting system installed, but there was some argument over its actual effectiveness. Andy H said that the mist felt like bugs hitting you - more annoying than cooling. They didn't use it while we were there.

That last session did make me think about the benefits of starting a camp like this at 4am, though. You could be done by 10am, then go and sleep somewhere cool. (I can just hear Andy groaning at the idea of getting up at 3am . . .)

[Paige 0]

Sounds like you guys had a lot of good flying going on! The heat can get you but I also found it to be far more tolerable than I had anticipated. Ari and I also flew during the day. The tunnel took off all the hair on my arms I loved the mysters, nothing at all like when it rains (even just sprinkling) at SVO (it can hurt if it pours). I found it to be most refreshing.

I could def. see the benefits of starting at 3am and ending at 10am though. Next time we visit, it's night flights for us.

How did you like the tunnel? Did you work w. any coaches out there?

Tunnel Pink Mafia Delegate
www.TunnelPinkMafia.com

[billvon 2,406]

>Did you work w. any coaches out there?

Yep. Last time it was Andy D and Eliana; this time it was Andy and Brian. Definitely worth it. I got 3 hours of airtime total, and it was all very focused 4-way training.

[diablopilot 2]

Or one could wait and got to one of the recirculating tunnels when they get the bugs worked out of an Air Conditioning unit for it.

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You're not as good as you think you are. Seriously.

[billvon 2,406]

>when they get the bugs worked out of an Air Conditioning unit for it.Smile

I don't think anyone's going to want to pay for that. A typical tunnel takes 300-600kW when it's running, and all that power turns right back into (you guessed it) heat. To get rid of that much heat you'd have to a) put a massive heat exchanger in (which would add drag and slow down the air) and b) pull an incredible amount of heat out of the coolant. You'd likely need more power to run the A/C than you'd need for the tunnel.

You could spray water, but the people at the Eloy tunnel don't seem to like it. (Plus the water out there would end up coating everything with minerals.) You could squirt liquid nitrogen into the airstream, but that stuff's expensive.

Here's another option. At the Eloy tunnel, the intake is already a bit underground. If you go down far enough (a few hundred feet) the ground is always about the same temperature - around 50F. So you dig out a big cave underground and suck air from there. A half billion cubic feet would be enough for six hours of operation, so you'd need a cave 100 feet tall by a half mile in each direction. Heck, Larry's got a backhoe!

[AggieDave 6]

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Here's another option. At the Eloy tunnel, the intake is already a bit underground. If you go down far enough (a few hundred feet) the ground is always about the same temperature - around 50F. So you dig out a big cave underground and suck air from there. A half billion cubic feet would be enough for six hours of operation, so you'd need a cave 100 feet tall by a half mile in each direction. Heck, Larry's got a backhoe!

Or a crapload of bags of ice on that giant square grid under the tunnel...then you'd have somewhere to put your beer.

Actually, I've been wondering about the temps in the tunnel, more to the point I've been wondering about the effectiveness of the electric motors in that kind of heat and sand. Wondering what that does to the brushings and such in the motors.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[Eule 0]

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You could spray water, but the people at the Eloy tunnel don't seem to like it.

I'm not sure what is being used now, but if it's the usual kind of mister you can get at the hardware store, I wonder if smaller droplets of water would help. Something like an ultrasonic humidifier or a high-pressure system (a few hundred PSI on up) with very fine nozzles.

At Eloy, there are electric heaters on the ceiling of the antechamber for when it's cold out. I don't remember what they were rated, but I do remember that you probably wouldn't need nearly that many heaters to heat a similarly-sized room that didn't have all that air moving by it. Having said that, I wonder if providing air conditioning in the antechamber would be of any use. The idea would be to cool it off a bit in the antechamber, so you could cool off in there instead of waiting for the fans to shut down and going completely out. You'd have to use a split system, with the evaporator and fan inside the antechamber and the condenser, fan, and compressor outside it - you'd only be moving Freon, not air, into and out of the pressurized area. Just like the heaters, the system would have to be relatively huge for the size of the room.

Eule

PLF does not stand for Please Land on Face.

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[TrickyDicky 0]

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>when they get the bugs worked out of an Air Conditioning unit for it.Smile

I don't think anyone's going to want to pay for that. A typical tunnel takes 300-600kW when it's running, and all that power turns right back into (you guessed it) heat. To get rid of that much heat you'd have to a) put a massive heat exchanger in (which would add drag and slow down the air) and b) pull an incredible amount of heat out of the coolant. You'd likely need more power to run the A/C than you'd need for the tunnel.

Afaik the bodyflight tunnel has 2 massive cooling units, that take more power than the tunnel itself. They dont have a problem with slow air.

UK Skydiver for all your UK skydiving needs.

[Paulipod 0]

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I don't think anyone's going to want to pay for that. A typical tunnel takes 300-600kW when it's running, and all that power turns right back into (you guessed it) heat. To get rid of that much heat you'd have to a) put a massive heat exchanger in (which would add drag and slow down the air) and b) pull an incredible amount of heat out of the coolant. You'd likely need more power to run the A/C than you'd need for the tunnel.

I have to agree it would be nicer if the power were free

Just in case youre interested in the actuals... our ratio of cooling to power is the same, but it actually takes slightly less cooling than the motor running (ie the motor is not 100% effiecent etc) also you get a little benefit with a low ambient etc.

Fortunately for us also our heat exchange coils simply replaced the air straightening filters so they go towards making the airflow better without too much power loss

Knowing the benefits / costs it would be a tough decision of which way to go if I were building from scratch in a new tunnel....

Bodyflight Bedford
www.bodyflight.co.uk

[billvon 2,406]

>Fortunately for us also our heat exchange coils simply replaced
>the air straightening filters so they go towards making the airflow
>better without too much power loss . . .

That makes sense, thanks.

[billvon 2,406]

>Having said that, I wonder if providing air conditioning in the
>antechamber would be of any use.

Seeing how heavily the antechamber is vented to the tunnel I doubt it. Amy and I learned where to stand to get the best blast of wind off the tunnel pretty quickly.

BTW the Perris tunnel has the same sort of heater arrangement. They don't seem to heat the air too much, but the radiant heat is definitely nice on cold days.