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Topic: Hot Air and Elevation (8 msgs / 469 lines)
1) From: John Carls
This is a multi-part message in MIME format.
Being new to the list, I don't know if it has been noted that another =
factor to consider when deciding on a roaster is elevation.  I found =
that here at 6,000 ft in the Colorado Rockies I could only roast- in a =
HWG - about 60g rather than the 90g that seems to be possible at sea =
level.  I attributed the difference to decreased fan efficiency =
resulting in decreased agitation.  I don't have any experience with the =
other hot air roasters but it would seem likely that they to would =
suffer the same problem.
John

2) From: EuropaChris
You're likely correct.  The air at 6000 ft. is significantly less dense then air at sea level.  The motor will compensate somewhat by spinning the fan faster due to the lower air density, but the density of the air is what's key to agitate the beans.  What you need is a turbocharger on the roaster to maintain sea level performance at high altitudes...just like an airplane. :-)
Chris
"John Carls"  wrote:
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3) From: nat
Thought you might enjoy this, posted first about a year ago

4) From: John Carls
Thanks for sharing that one Nat.  And I hadn't thought about a taste
difference in beans roasted at different altitudes.  However I am heading to
Phoenix towards the end of October and I think I will take my roaster and
compare a batch from here and one I'll roast there.
As I think about it, maybe there are other factors at work here - like the
efficiency of heat tranfer from the coil to the surrounding air and then to
the beans.  Less dense air would lower it and slow the roast.  And maybe the
lower pressure effects the release of oils and CO2 and the time and
temperature of the cracks.  Not that I can do anything about it - but its
fun to contemplate.
And Kevin, it seems that back when I was flying hot air balloons we learned
that there was about a 15 to 20% decrease in burner efficiency between sea
level and 6,000 ft.  I assume a gas fired roaster would be in the same
range.
John

5) From: Rlb0803
Great story, Nat.  But when you're doing the roasting, who's flying the plane?
Also, I can't get your website link to work. I get a message saying the web site page isn't found.
Rob
About six months ago I was introduced to the art -- or should I say sport -- of coffee roasting.  I purchased all the appropriate paraphernalia including the very excellent Hearthware Gourmet coffee roaster.  I experimented with literally dozens of different green beans, both caffeinated and decaffeinated.  I would be happy to pass on some of
my blending secrets, but I think a more than adequate job has been done by literally dozens of other contributors to this and other newsgroup threads.  Therefore, I will restrict my comments to areas I suspect remained unexplored -- so far.
To make a long story short, I became so passionate about coffee roasting and I found that I wanted to discover new options for enhancing coffee flavor.  I had a secondary motive as well.  I wanted to explore ways inwhich I could always have freshly roasted coffee (mellowed 12 to 36 hours of course, depending on the blend) available to me wherever I travel.
Happily, I was able to accommodate both these objectives and I wanted pass on some of my findings to you and solicit your kind and generous comments back.
A quick note: I, like you, have tried numerous combinations of green beans, roasting them separately or together for roasting times that results in a final product which expresses the full color spectrum from an acidic light tan to charcoal singed black.  In the end analysis, I found a combination of
coffees and roasting times to make me happy and make my pallet sing.  I have found invariably that blends are better than single source beans. I too have found that each bean requires a different roasting time. Therefore, I might roast an Ethiopian bean for seven minutes and a Mexican bean for six minutes and 45 seconds.  I then blend these beans together to make a superb combo.
Of course, I purchased an extra coffee roasting unit for my vacation home at Lake Tahoe.  It was there that this adventure began.  I noticed that the coffee flavors extracted from beans roasted at the 5247 foot altitude of Tahoe tasted quite different - and much better - than those roasted at 625 foot level in my home at the San Francisco Bay Area.  At first I didn't make too much of this, but soon I discovered that I
preferred the high altitude roasted beans. My hypothesis was that a reduced atmospheric pressure improved roasting quality. I wondered what would happen if I extended this phenomenon too much higher altitudes and hence much lower pressures.
I fly a light jet called a CitationJet.  This sturdy craft allows me to fly to altitudes of 41,000 feet. At 41,000 feet the pressure is so low that the meager oxygen content of the air cannot sustain human life and exposed human beings lapse into unconsciousness within 20 seconds.  I wondered what would happen if I roasted coffee in the virtual vacuum of
41,000 feet.  If I were able to roast coffee at this lofty altitude its quality should be superb.  And better yet, this would accommodate my dual goals of roasting mobility and high altitude experimentation.
In order to accommodate roasting in a virtual vacuum, I needed to tap into a hot air supply outside the pressure vessel (known to you as the cabin) of the aircraft.  Fortunately, the CitationJet has just such an area aft of the rear pressure bulkhead (behind the rear seat).  This area is not pressurized and has plenty of available hot air. Pneumatically speaking, a steam of "bleed air" is used for many functions in the Jet. Pressurized bleed air starts out at the jet engine (this air is really, really hot -- about 800 degrees centigrade) and then passes through a first level intercooler that brings down the temperature to about 500 degrees centigrade.  In the aforementioned compartment behind the bulkhead, the 500-degree air is mixed with additional cool air by two additional intercoolers to provide many different pneumatic airplane functions including pressurization and cabin heat.  I have included a pneumatic schematic, figure 2 at website below.
By tapping this 500-degree air, and mixing it with ambient cooler air in the compartment, I was able to achieve a forced air stream at 23 PSI (pounds per square inch) at approximately 425 degrees Fahrenheit.  As I am sure you are aware, this is almost exactly the correct temperature for coffee roasting. (I did initially experiment with pure bleed at 800
degrees C hoping to get to the fabled 'third crack', but the roast was a way too dark). 
My next task was to design a way to hold a coffee-roasting flask such as the glass receptacle of the Hearthware Gourmet coffee roaster. This is easily accomplished (see figure 3 at web site below) and hot air can be forced through the glass receptacle almost exactly in the way that the actual Hearthware unit works when resting on its own base.
This arrangement works perfectly.  However, a somewhat longer roast time is required than you might imagine.  Why?  Because the ambient temperature in the compartment is extremely cold.  In fact, the temperature outside the aircraft at 41,000 feet can be as low as -60 degrees centigrade.  In the compartment, the temperature is probably closer to -20 degrees centigrade.  When the green beans are that cold initially, they take a longer time to roast to perfection.  One of the
great advantages of roasting and high altitudes is that the roasted coffee cools very rapidly once the roasting period is over.  This may significantly contribute to the spectacular quality of high altitude roasting. There may be another advantage: high altitude roasting may facilitate out gassing of CO2 enabling you to enjoy a cup immediately
upon landing instead of waiting for 24 hrs. 
I have even started to consider new modification to my aircraft that would allow me to retrieve the roasted beans while still in flight. To do this, I would have to create a pressurization camber and a means of dragging the beans to the front of the plane.  Any ideas?  (Please see photo 1 at website below to view the area under the floor of the
aircraft. This area houses many control cables but may be big enough to haul one third of a cup of beans from the roasting area to the cockpit of the craft).
For those of you interested in converting your own CitationJet  - or other jet for that matter - into an airborne roasting system, you may contact me for details on how to work with the Federal Aviation Administration (FAA) to get the appropriate authorization for modifying your aircraft.  Under no circumstances should you attempt this modification without the assistance of an authorized and licensed Airframe Inspector who in turn will be required obtained a special
certificate for your aircraft from a friendly FAA representative at your local FISDO at a major airport in your area.
The only good news here is that modifying my aircraft in this way was reasonably inexpensive when compared with other major modifications.  I was able to accomplish this modification for only $47,322.15.  Truly remarkable given the requirement for engineering documents, design specifications, heat dissipation calculations, mechanical engineering, timed flapper valves, the physical design of the receptacle holder and
its construction from a combination of exotic metals and plastics plus two certified mechanics for two weeks. I have not included any charge for my time running around between federal officials, parts manufacturers and so on.  Believe me, I have done much simpler modifications to the aircraft that cost much more, most notable the installation of a Faema espresso machine in my aircraft galley.
Roasting coffee at these altitudes is of course very efficient if you are already flying your jet somewhere.  However, if you were to fly your jet solely for the purpose of roasting coffee, the per cup cost would be
very high indeed.  
Given that:
- the Hearthware glass roasting container I use roasts only
one-third of the cup of green beans at a time
- and given that it is likely that you would need to be airborne for in excess of one hour to fly to an altitude of 41,000 feet, roast,
and then descend again to land the cost per cup of coffee made from beans roasted in this way might well exceeded $350.  No matter how good the roast may be you'd have to be very wealthy indeed to accommodate such foolish excess.
Next steps: I have several friends who are a part of our American space program through NASA.  Roasting in the absolute the vacuum of space is a possibility so exciting that the mind reels.  Stay tuned.
I welcome your comments, ideas and suggestions.  At all I can say to you is great coffee and godliness are remarkably close together, especially when you are sipping an espresso so close to heaven at 41,000 feet.
Please see photos and diagrams athttp://lists.sweetmarias.com/mailman/listinfo/homeroast">http://communities.msn.com/PlaneCoffeehomeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

6) From: Mark A. Chalkley
Hmmm.  Methinks it's too long until April for this.  Of course, the
"Hot Air" in the subject could be a bit less literal than we're being
let to believe, too...
Mark C.
On Saturday, September 21, 2002, 10:47:07 PM, you wrote:
Rac> Great story, Nat.  But when you're doing the roasting, who's flying the plane?
Rac> Also, I can't get your website link to work. I get a message saying the web site page isn't found.
Rac> Rob
Rac> About six months ago I was introduced to the art -- or should I say sport -- of coffee roasting.  I purchased all the appropriate paraphernalia including the very excellent Hearthware Gourmet
Rac> coffee roaster.  I experimented with literally dozens of different green beans, both caffeinated and decaffeinated.  I would be happy to pass on some of
Rac> my blending secrets, but I think a more than adequate job has been done by literally dozens of other contributors to this and other newsgroup threads.  Therefore, I will restrict my comments to
Rac> areas I suspect remained unexplored -- so far.
Rac> To make a long story short, I became so passionate about coffee roasting and I found that I wanted to discover new options for enhancing coffee flavor.  I had a secondary motive as well.  I
Rac> wanted to explore ways inwhich I could always have freshly roasted coffee (mellowed 12 to 36 hours of course, depending on the blend) available to me wherever I travel.
Rac> Happily, I was able to accommodate both these objectives and I wanted pass on some of my findings to you and solicit your kind and generous comments back.
Rac> A quick note: I, like you, have tried numerous combinations of green beans, roasting them separately or together for roasting times that results in a final product which expresses the full color
Rac> spectrum from an acidic light tan to charcoal singed black.  In the end analysis, I found a combination of
Rac> coffees and roasting times to make me happy and make my pallet sing.  I have found invariably that blends are better than single source beans. I too have found that each bean requires a
Rac> different roasting time. Therefore, I might roast an Ethiopian bean for seven minutes and a Mexican bean for six minutes and 45 seconds.  I then blend these beans together to make a superb combo.
Rac> Of course, I purchased an extra coffee roasting unit for my vacation home at Lake Tahoe.  It was there that this adventure began.  I noticed that the coffee flavors extracted from beans roasted
Rac> at the 5247 foot altitude of Tahoe tasted quite different - and much better - than those roasted at 625 foot level in my home at the San Francisco Bay Area.  At first I didn't make too much of
Rac> this, but soon I discovered that I
Rac> preferred the high altitude roasted beans. My hypothesis was that a reduced atmospheric pressure improved roasting quality. I wondered what would happen if I extended this phenomenon too much
Rac> higher altitudes and hence much lower pressures.
Rac> I fly a light jet called a CitationJet.  This sturdy craft allows me to fly to altitudes of 41,000 feet. At 41,000 feet the pressure is so low that the meager oxygen content of the air cannot
Rac> sustain human life and exposed human beings lapse into unconsciousness within 20 seconds.  I wondered what would happen if I roasted coffee in the virtual vacuum of
Rac> 41,000 feet.  If I were able to roast coffee at this lofty altitude its quality should be superb.  And better yet, this would accommodate my dual goals of roasting mobility and high altitude
Rac> experimentation.
Rac> In order to accommodate roasting in a virtual vacuum, I needed to tap into a hot air supply outside the pressure vessel (known to you as the cabin) of the aircraft.  Fortunately, the CitationJet
Rac> has just such an area aft of the rear pressure bulkhead (behind the rear seat).  This area is not pressurized and has plenty of available hot air. Pneumatically speaking, a steam of "bleed air"
Rac> is used for many functions in the Jet. Pressurized bleed air starts out at the jet engine (this air is really, really hot -- about 800 degrees centigrade) and then passes through a first level
Rac> intercooler that brings down the temperature to about 500 degrees centigrade.  In the aforementioned compartment behind the bulkhead, the 500-degree air is mixed with additional cool air by two
Rac> additional intercoolers to provide many different pneumatic airplane functions including pressurization and cabin heat.  I have included a pneumatic schematic, figure 2 at website below.
Rac> By tapping this 500-degree air, and mixing it with ambient cooler air in the compartment, I was able to achieve a forced air stream at 23 PSI (pounds per square inch) at approximately 425
Rac> degrees Fahrenheit.  As I am sure you are aware, this is almost exactly the correct temperature for coffee roasting. (I did initially experiment with pure bleed at 800
Rac> degrees C hoping to get to the fabled 'third crack', but the roast was a way too dark). 
Rac> My next task was to design a way to hold a coffee-roasting flask such as the glass receptacle of the Hearthware Gourmet coffee roaster. This is easily accomplished (see figure 3 at web site
Rac> below) and hot air can be forced through the glass receptacle almost exactly in the way that the actual Hearthware unit works when resting on its own base.
Rac> This arrangement works perfectly.  However, a somewhat longer roast time is required than you might imagine.  Why?  Because the ambient temperature in the compartment is extremely cold.  In
Rac> fact, the temperature outside the aircraft at 41,000 feet can be as low as -60 degrees centigrade.  In the compartment, the temperature is probably closer to -20 degrees centigrade.  When the
Rac> green beans are that cold initially, they take a longer time to roast to perfection.  One of the
Rac> great advantages of roasting and high altitudes is that the roasted coffee cools very rapidly once the roasting period is over.  This may significantly contribute to the spectacular quality of
Rac> high altitude roasting. There may be another advantage: high altitude roasting may facilitate out gassing of CO2 enabling you to enjoy a cup immediately
Rac> upon landing instead of waiting for 24 hrs. 
Rac> I have even started to consider new modification to my aircraft that would allow me to retrieve the roasted beans while still in flight. To do this, I would have to create a pressurization
Rac> camber and a means of dragging the beans to the front of the plane.  Any ideas?  (Please see photo 1 at website below to view the area under the floor of the
Rac> aircraft. This area houses many control cables but may be big enough to haul one third of a cup of beans from the roasting area to the cockpit of the craft).
Rac> For those of you interested in converting your own CitationJet  - or other jet for that matter - into an airborne roasting system, you may contact me for details on how to work with the Federal
Rac> Aviation Administration (FAA) to get the appropriate authorization for modifying your aircraft.  Under no circumstances should you attempt this modification without the assistance of an
Rac> authorized and licensed Airframe Inspector who in turn will be required obtained a special
Rac> certificate for your aircraft from a friendly FAA representative at your local FISDO at a major airport in your area.
Rac> The only good news here is that modifying my aircraft in this way was reasonably inexpensive when compared with other major modifications.  I was able to accomplish this modification for only
Rac> $47,322.15.  Truly remarkable given the requirement for engineering documents, design specifications, heat dissipation calculations, mechanical engineering, timed flapper valves, the physical
Rac> design of the receptacle holder and
Rac> its construction from a combination of exotic metals and plastics plus two certified mechanics for two weeks. I have not included any charge for my time running around between federal officials,
Rac> parts manufacturers and so on.  Believe me, I have done much simpler modifications to the aircraft that cost much more, most notable the installation of a Faema espresso machine in my aircraft
Rac> galley.
Rac> Roasting coffee at these altitudes is of course very efficient if you are already flying your jet somewhere.  However, if you were to fly your jet solely for the purpose of roasting coffee, the
Rac> per cup cost would be
Rac> very high indeed.  
Rac> Given that:
Rac> - the Hearthware glass roasting container I use roasts only
Rac> one-third of the cup of green beans at a time
Rac> - and given that it is likely that you would need to be airborne for in excess of one hour to fly to an altitude of 41,000 feet, roast,
Rac> and then descend again to land the cost per cup of coffee made from beans roasted in this way might well exceeded $350.  No matter how good the roast may be you'd have to be very wealthy indeed
Rac> to accommodate such foolish excess.
Rac> Next steps: I have several friends who are a part of our American space program through NASA.  Roasting in the absolute the vacuum of space is a possibility so exciting that the mind reels. 
Rac> Stay tuned.
Rac> I welcome your comments, ideas and suggestions.  At all I can say to you is great coffee and godliness are remarkably close together, especially when you are sipping an espresso so close to
Rac> heaven at 41,000 feet.
Rac> Please see photos and diagrams at
Rac>http://communities.msn.com/PlaneCoffeeRac>
Rac> homeroast mailing list
Rac>http://lists.sweetmarias.com/mailman/listinfo/homeroast">http://lists.sweetmarias.com/mailman/listinfo/homeroasthomeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

7) From: Ben Treichel
Hey Nat,
I'm sure that Tom & Maria would love to 'weekend' at your place in 
Tahoe. At the same time you can show them how you make 'planecoffee" ;-)
Ben
Rlb0803 wrote:
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8) From: sho2go
;-)   ;-)   ;-)
<Snip>
is great coffee and godliness are remarkably close together, especially when
you are sipping an espresso so close to heaven at 41,000 feet.
<Snip>
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast


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