Question about being unpressurized at higher (Class A) altitudes

es330td wrote:

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.

He can't legally rent you his Velocity.


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.

Ask you CFI about it. While the Velocity is a hell of a plane it isn't a
Citation or King Air.

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.

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.

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?

Matt Barrow writes:

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

Less drag is a big advantage. The higher an aircraft flies, the more easily
you can move it forward. Ultimately, you end up in outer space, with no air,
and then you don't need any energy at all to keep it moving forward (the
principle behind hypersonic aircraft). This is one reason why the SR-71 is
very efficient in cruise. It's also a reason why jets fly high even though
the engines produce less power at high altitudes--the power required to
maintain a given speed decreases faster than the power provided by the
engines, as altitude increases (within certain limits).

Mxsmanic wrote in
:

Matt Barrow writes:

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

Less drag is a big advantage. The higher an aircraft flies, the more
easily you can move it forward. Ultimately, you end up in outer
space, with no air, and then you don't need any energy at all to keep
it moving forward (the principle behind hypersonic aircraft). This is
one reason why the SR-71 is very efficient in cruise. It's also a
reason why jets fly high even though the engines produce less power at
high altitudes--the power required to maintain a given speed decreases
faster than the power provided by the engines, as altitude increases
(within certain limits).


Wrong again, bozo


Bertie

On Sep 13, 10:41 pm, "Matt Barrow"
wrote:
"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?

It gains efficiency because you can move faster for the same engine
power. If you disregard drag, then you might as well disregard the
engine too because thrust = drag at level unaccelerated flight.

"Andrew Sarangan" wrote in message
oups.com...
On Sep 13, 10:41 pm, "Matt Barrow"
wrote:
"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?

It gains efficiency because you can move faster for the same engine
power.

That's not the airframe gainning efficeincy, that's called a reduction in
drag.

If you disregard drag, then you might as well disregard the
engine too because thrust = drag at level unaccelerated flight.

I'll have to dig through my library of physics books to 'splain that one.
:~)

The engine loses the _ability_ to generate power, but that has noting to do
with your T=D formula.

Think: turbocharging.

The airframe is static, so there's no gain or loss in efficiency.

Now, if you have a wing like the F-14, that could be considered as a whole
different story.

On Sep 13, 8:48 pm, Andrew Sarangan wrote:

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.- Hide quoted text -

The Velocity won't go that high; according to the specs on their
website the RG Velocities top out about FL200. The Cozy based
Aerocanard will go to FL250, according to http://www.aerocad.com/Performance.htm.
While they could be completely full of it, I don't see too many people
trusting their life and paying over $30K for a homebuilt kit to a
company that lies about its planes' performance numbers.