Question about being unpressurized at higher (Class A) altitudes

Al G wrote:
Gawd, don't let the glider folks hear you say that.

Al G

Hey!

I heard that...

--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums...ation/200709/1

On Sep 13, 2:40 pm, "Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net
wrote:
es330td wrote:

He can't legally rent you his Velocity.

I didn't know that.

On Sep 13, 4:24 pm, Bob Moore wrote:
es330td wrote

I know that planes gain efficiency at altitude but
I don't know how high one must go to realize those gains.

Very true with jet engines....not so much with piston engines.
If you aren't turbocharged, you'll never make Class A airspace.

Bob Moore

The specs on the Aerocanard FG state that with an LIO-360 engine the
service ceiling is FL250. Not that I would be trying to make Class A
but according to the definition of service ceiling shouldn't this
plane be able to at least make FL180 and then some?

es330td wrote:


By the time this plane is built the kids will
probably be 5 or more years older




No way you get it done in less than 10 years. I've seen it countless times.


My CFI flies King
Air 350's and Citation Jets for hire so I am used to hearing about his
experiences, something very different than the flying I will be doing.


You won't be going that high.

"es330td" wrote:


The specs on the Aerocanard FG state that with an LIO-360 engine the
service ceiling is FL250. Not that I would be trying to make Class A
but according to the definition of service ceiling shouldn't this
plane be able to at least make FL180 and then some?

Yes, but you probably wouldn't want to do it.

It would probably take a long time to climb that high in a naturally-aspirated
airplane, then there's the bother and discomfort of wearing a mask once you
got there.

I think you'll find the low teens is as high as you'll want to go in the
airplane you're proposing.

--
Dan
T-182T at BFM

"John" wrote

I am not at all sure if this is accurate, but Ernie Gann in his book
"Fate is the Hunter" described an episode where he was carrying troops
in the back and they were getting a bit out of hand. He climbed and
the reduced oxygen resulted in a cabin of slumbering souls.

In airliners, all you have to do is change the cabin altitude pressure
setting, and you can do the same thing, and they do occasionally do this on
(especially on) oceanic red-eyes.

They don't have to go all that high to have a noticeable effect, but it does
make it easy for the flight attendants.
--
Jim in NC

On Sep 13, 2:34 pm, es330td wrote:
On Sep 13, 9:47 am, es330td wrote:

My father has a C182 in which I have been to about 10K ft MSL. I am
currently working on my license and am considering building a Velocity
or Aerocanard, both of which have ceilings up into Class A airspace,
one as high as FL250. (Before anyone cautions me about building one
of these, I know two people with Velocities and a local builder who
has built multiple canard aircraft. I will have lots of support and
will have logged PIC time in one long before mine is built.) While I
know that oxygen is required at altitude, what is the effect of the
lower pressure on pilot and passengers? I am doing this in part for
the purpose of transporting myself and family to visit friends and
relatives and am curious about the effect on my two children,
currently 3 and 5, and whether this will make them less pleasant to
fly with.

TIA

Thanks for everyone's responses. I am somewhat lacking in knowledge
at this point; I know my desires but not the specifics of
implementation. By the time this plane is built the kids will
probably be 5 or more years older but if my friend with the Velocity
lets me rent it it may be an issue sooner. I know that planes gain
efficiency at altitude but I don't know how high one must go to
realize those gains. I just assumed that with a service ceiling over
FL200 that pilots would generally want to go there. My CFI flies King
Air 350's and Citation Jets for hire so I am used to hearing about his
experiences, something very different than the flying I will be doing.

The airframe gains efficiency with altitude, but the engine loses
efficiency with altitude. So there is an optimum altitude where you
get the best performance. This happens to be around 8000 ft for
normally aspirated engines. Turbo charging will push this to a higher
altitude.

I don't know where you got the information that Velocity has a service
ceiling of 25k. It is not the airframe that determines the service
ceiling as much as the engine choice.

"Andrew Sarangan" wrote in message
ups.com...

The airframe gains efficiency with altitude, but the engine loses
efficiency with altitude.

How does the airframe "gain efficiency" at altitude, aside from generating
less drag?

On Sep 13, 10:51 pm, "Marc J. Zeitlin"
wrote:
es330td wrote:
..... While I know that oxygen is required at altitude, what is the
effect of the lower pressure on pilot and passengers? I am doing
this in part for the purpose of transporting myself and family to
visit friends and relatives and am curious about the effect on my
two children, currently 3 and 5, and whether this will make them
less pleasant to fly with.

You've gotten a number of reasonable answers from folks that don't fly
canard aircraft of this type - here's some info from someone that
does. I have a COZY MKIV with an O-360-A2A 180 HP engine. I
regularly fly at 13.5K ft., and have been to 15.5K ft. once. The
reasons to go that high are to get above the haze layer, get above a
cloud layer, see distant T-storm buildups, miss mountains, and get
into more favorable winds to get better fuel economy.

I normally fly around 7.5K ft - 10.5K ft., as the plane is fastest
down there (at 60-75% power) and I don't need O2. I'll go higher for
short periods of time for ground clearance when crossing the Rockies
or Sierras, or when flying over northern AZ where the ground's at 7.5K ft.

Above 18K ft., you'd have to wear a mask, rather than a cannula. The
Cannula is not particularly intrusive, but masks are. Plus, you'd
have to be on an IFR flight plan (and obviously be IR). There are a
few canard folks that regularly fly in the low 20's, but only when the
winds are favorable (generally going east).

At any rate, assuming that you've got O2 on yourself and your family,
up to 18K with cannulae, you're fine (get a pulse Oximeter so that you
can measure your blood's saturated O2 levels to make sure you're
actually getting the O2). The lower pressure has essentially no
effect, if you've got O2.

Keeping cannulae on little kids would be difficult, but as you state,
it'll be a few years (not 10, as proposed - it took 7 for me to build
my COZY, but I know many folks that have built canard aircraft in 2-5
years) before they're actually flying. In fact, per 91.211, they
don't HAVE to have O2 unless you're above 15K ft., so you can fly up
to there, use O2 for yourself, and let them nap in the back without O2.

If you're seriously considering a canard aircraft, I suggest that you
join the COZY mailing list and/or the yahoo canard-aviators mailing
list, to get information directly from hundreds of folks building and
flying canard aircraft. There are only a few Aerocanards flying (less
than 15 - maybe less than 10), and there's no specific list for them.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2007

Thanks for this response. I am serious about owning a canard; I can't
find a manufactured plane that will give me the range and speed to
make the cross country flying worth doing at a cost I can afford. I
am leaning toward the Aerocanard as it is kit rather than plans built
so it should get flying sooner rather than later.

To all: This discussion has been very educational. I haven't learned
yet at what altitude a plane gives maximum performance at cruise power
though from these responses it appears that under FL100 is expected
and preferred. I guess I'll leave Class A to the turbine powered
airplanes.

Es330td,

I guess I'll leave Class A to the turbine powered
airplanes.


Not to worry, there are plenty of countries with Class A way below
FL100.

--
Thomas Borchert (EDDH)