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BrokenAeroVT
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Newbie

Postby BrokenAeroVT » Fri Sep 18, 2009 9:32 pm

Hi. I'm Tim, AKA BrokenAeroVT from YouTube.

I'm a seasoned hiker who is getting into ultralight backpacking. I have a BS in Aerospace and Ocean Engineering from Va Tech.

While my background is in engineering, I've never contemplated stove building before, so the more I can apply what I understand to ultralight backpacking stoves, the more videos I will put out. I have 4 videos about stove design. Hope you will take a look.

Right now I have two possibly three stove designs I'm seriously contemplating building. I'm just working out some of the kinks. One problem was making them too powerful. Boil time is limited by a phenomenon called the Leidenfrost Effect.

I shared this knowledge with Jason who promptly called Tinny about it. Tinny immediately made a recent video poo pooing such a limit without mentioning any specifics. :roll: I don't know where he is drawing his confidence from.

Problem is, when heat is applied too quickly to a pot, bubbles form that insulate the water from the heat. The pot overheats and the water never boils. You know what happens to an overheated Heiny.

I've run into this phenomenon at 50-60 second "boil times" (two cups of water). No matter how much fuel I add to the stove, the water just will not boil. I haven't gotten a tight fix on the limit, but I suspect it is in the ball park of to 60-90 seconds.

I contemplated overcoming this limit with a pressure cooker, then bubbles won't form at the usual boiling point of 100C since the boiling point will change to a higher temperature. You reach 100C then stop. But that would be kind of heavy to carry on the trail, wouldn't it? ;)

The other idea would be to just stir the water with a brush to displace the bubbles. Kind of makes life a little complicated, doesn't it?

There is a patent online for overcoming the Leidenfrost Effect with a bubble displacement technique for a different application, so the Leidenfrost Effect can be overcome in theory for boiling water. It's just that doing so adds weight and complexity to a stove, something we are trying to overcome as ultralight backpackers, hey?

So, when I get to the point I can fine tune my stoves to boil just before the Leidenfrost Effect, I'll post some videos. 60-90 seconds is enough for a two cup boil time, don't you think? :)

realityguy
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Re: Newbie

Postby realityguy » Fri Sep 18, 2009 9:58 pm

So, when I get to the point I can fine tune my stoves to boil just before the Leidenfrost Effect, I'll post some videos. 60-90 seconds is enough for a two cup boil time, don't you think? :)


Welcome!..and make sure it weighs less than an ounce or two..Okay?.. :mrgreen:
The views and opinions expressed by this person are his own and not the general consensus of others on this website.Realityguy

BrokenAeroVT
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Re: Newbie

Postby BrokenAeroVT » Fri Sep 18, 2009 10:17 pm

realityguy wrote:
So, when I get to the point I can fine tune my stoves to boil just before the Leidenfrost Effect, I'll post some videos. 60-90 seconds is enough for a two cup boil time, don't you think? :)


Welcome!..and make sure it weighs less than an ounce or two..Okay?.. :mrgreen:


Thankee!

At 28.4 grams per ounce, that shouldn't be a problem. Should be less than 15 g for one and might be a little heavier for the other because of need for metals that can take the heat stress. Enormously simple stove that should allow isopropyl to be used without sooting effects.

Isopropyl packs more heat per unit weight. it just needs stoichiometric attention. Stoichiometry is indespensible to stove design. It's worth learning its meaning and application to stoves.

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Ridgerunner
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Re: Newbie

Postby Ridgerunner » Fri Sep 18, 2009 11:54 pm

Hello Tim, It's great to have you on the board. You have some interesting ideas coming from a more scientific point of view. Your finned stove looks interesting and the cow video was a hoot! :lol: :lol: :lol: If you can bring 2 cups of water to a boil with Isopro in 60 -90 sec. and no soot, you will move to the head of the class. :lol: Good luck with your ideas and let us know if we can be of any help. ;) OH, and as far as....
You know what happens to an overheated Heiny.
I'm not going to touch that one! :lol:
"Many of lifes failures are people who did not realize how close they were to success when they gave up".....Thomas Edison

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Vibe
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Re: Newbie

Postby Vibe » Fri Sep 18, 2009 11:58 pm

Ridgerunner wrote:Hello Tim, It's great to have you on the board. You have some interesting ideas coming from a more scientific point of view. Your finned stove looks interesting and the cow video was a hoot! :lol: :lol: :lol: If you can bring 2 cups of water to a boil with Isopro in 60 -90 sec. and no soot, you will move to the head of the class. :lol: :

LOL. If he can do it in 2 or 3 times that yime he'll still be there. Anyone have a direct link to the videos?

Ridgerunner wrote:Good luck with your ideas and let us know if we can be of any help. ;) OH, and as far as....
You know what happens to an overheated Heiny.
I'm not going to touch that one! :lol:

Wise move RR. :DBfire:
The opinion of 10,000 men is of no value if none of them know anything about the subject.
- Marcus Aurelius--------------------------------------------- Image

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Ridgerunner
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Re: Newbie

Postby Ridgerunner » Sat Sep 19, 2009 12:20 am

LOL. If he can do it in 2 or 3 times that yime he'll still be there. Anyone have a direct link to the videos?

http://youtube.com/BrokenAeroVT

The fighting cow reminds me of the salmon commercial where the guy fights the bear for the fish :lol:
"Many of lifes failures are people who did not realize how close they were to success when they gave up".....Thomas Edison

"Live Life....Love Life....Ask More !

BrokenAeroVT
Posts: 54
Joined: Fri Sep 18, 2009 5:49 pm

Re: Newbie

Postby BrokenAeroVT » Sat Sep 19, 2009 12:34 am

Ridgerunner wrote:Hello Tim, It's great to have you on the board. You have some interesting ideas coming from a more scientific point of view. Your finned stove looks interesting and the cow video was a hoot! :lol: :lol: :lol: If you can bring 2 cups of water to a boil with Isopro in 60 -90 sec. and no soot, you will move to the head of the class. :lol: Good luck with your ideas and let us know if we can be of any help. ;) OH, and as far as....
You know what happens to an overheated Heiny.
I'm not going to touch that one! :lol:


I could use a source for a thin, lightweight, drillable cylindrical cup of brass or steel about 7/8 to 1-1/4 inch in diameter and about the same in height. A plumbing line copper end cap is too heavy for my tastes. Aluminum's melting point is too low for use as a mixing chamber. Anyone have any suggestions for local sources? I live in Virginia Beach.

Vibe
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Re: Newbie

Postby Vibe » Sat Sep 19, 2009 12:46 am

BrokenAeroVT wrote:I could use a source for a thin, lightweight, drillable cylindrical cup of brass or steel about 7/8 to 1-1/4 inch in diameter and about the same in height. A plumbing line copper end cap is too heavy for my tastes. Aluminum's melting point is too low for use as a mixing chamber. Anyone have any suggestions for local sources? I live in Virginia Beach.

I wouldn't think that you would really want that chamber getting as hot as AL melting point - but in your engineering endeavors, have you run across Bimba Cylinders. the have several "non repairable" types with thin SS walls and AL end caps crimped in.
The opinion of 10,000 men is of no value if none of them know anything about the subject.
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Ridgerunner
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Re: Newbie

Postby Ridgerunner » Sat Sep 19, 2009 1:19 am

Tim, your videos are well done and offer much fuel for thought. Your sense of humor put a big ol' smile on this ugly mug...thanks.... as far as copper caps go...what about welding/brazing thin brass or stainless sheeting?
"Many of lifes failures are people who did not realize how close they were to success when they gave up".....Thomas Edison

"Live Life....Love Life....Ask More !

BrokenAeroVT
Posts: 54
Joined: Fri Sep 18, 2009 5:49 pm

Re: Newbie

Postby BrokenAeroVT » Sat Sep 19, 2009 1:51 am

Ridgerunner wrote:Tim, your videos are well done and offer much fuel for thought. Your sense of humor put a big ol' smile on this ugly mug...thanks.... as far as copper caps go...what about welding/brazing thin brass or stainless sheeting?


I'm not equipped for welding beyond copper, and I don't believe that weld can endure the heat of a mixing chamber. I'm afraid I'm not familiar with welding steel and brass. I was hoping to find something preconstructed in the dimensions I provided, maybe something like a ss salt shaker, provided it's drillable. Maybe my drill sucks, but I tried drilling through walmart's tiny ss cups from their kitchenware section without any success.


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