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.