Lancair Legacy Design Flaw?

Alan Baker wrote:

Anyone who thinks an aircraft can be made "foolproof" is a fool who
shouldn't be flying.


You won this round, Alan!

--

Richard

(remove the X to email)

"Vaughn Simon" wrote in message
...

"Gregory Hall" wrote in message
...


It looks too much like an irresponsible, hot rod, stunt plane to me.

Well, you sucked me in at first, so on a troll scale of zero-to-10 you
rate at least a five. How are things in France?

Vaughn


France? I don't live in France. I built and used to fly a Rotec Rally 2B
many years ago. It was a tail dragger with a high wing and the motor was
mounted atop the wind with a pusher prop.

When I got it trimmed out correctly at cruise speeds I could lean forward in
the seat to nose it down and lean back in the seat to nose it up. Even as
well-balanced as it was at about half throttle, when the engine quit it
would pitch up immediately and drastically because the high engine placement
and pusher prop had enough leverage so that the proper trim at the tail
counteracted the nose down force of the engine and prop. If you didn't
immediately push the stick way forward when the engine quit it was a matter
of seconds before it would nose up fast and stall and then you would have no
control at all from the stick until it fell for a while and the nose dropped
(thank god for that) so you could gain speed provided you had enough
altitude to get control of it again. But it didn't glide too well being a
single surface wing with wire bracing. Perhaps 2:1 glide ratio. But it was
easy to land with no power but you had to come in hot and steep and at the
last second pull back on the stick and flare it.

It looks to me like the Legacy would act pretty much the same if the engine
quit.

--
Gregory Hall

On Oct 30, 5:12*pm, "Gregory Hall" wrote:
"Vaughn Simon" wrote in message

...



"Gregory Hall" wrote in message
...

It looks too much like an irresponsible, hot rod, stunt plane to me.

* Well, you sucked me in at first, so on a troll scale of zero-to-10 you
rate at least a five. *How are things in France?

Vaughn

France? *I don't live in France. I built and used to fly a Rotec Rally 2B
many years ago. It was a tail dragger with a high wing and the motor was
mounted atop the wind with a pusher prop.

When I got it trimmed out correctly at cruise speeds I could lean forward in
the seat to nose it down and lean back in the seat to nose it up. Even as
well-balanced as it was at about half throttle, when the engine quit it
would pitch up immediately and drastically because the high engine placement
and pusher prop had enough leverage so that the proper trim at the tail
counteracted the nose down force of the engine and prop. If you didn't
immediately push the stick way forward when the engine quit it was a matter
of seconds before it would nose up fast and stall and then you would have no
control at all from the stick until it fell for a while and the nose dropped
(thank god for that) so you could gain speed provided you had enough
altitude to get control of it again. But it didn't glide too well being a
single surface wing with wire bracing. Perhaps 2:1 glide ratio. But it was
easy to land with no power but you had to come in hot and steep and at the
last second pull back on the stick and flare it.

It looks to me like the Legacy would act pretty much the same if the engine
quit.

--
Gregory Hall

Oh for gawd sake, you are talking about two totally different designs
and the aerodynamics of the two are totally different. The Lancair is
NOT a pusher and the engine is mounted forward of the CG instead of on
top of it. When the engine quits it will not pitch upward. The plane
you flew had the engine well above the center of gravity with a pusher
prop and as a result produced a force that pushed the nose of the
aircraft down. The two planes would not act pretty much the same at
all. The weight of the engine on the Legacy is forward of the CG and
as a result always pulling the nose of the plane down. The counter to
the nose down is the horizontal stabilizer and the elevator. Look at
the angle of incedence on the Horizontal Stabilizer and you will find
a slight downward angle, not an upward angle as is common on the
wing. This counteracts the force from the weight of the engine. An
engine out condition will not have a significant effect on pitch until
the airspeed changes and that will result in a nose down, not nose up
pull.

On Thu, 30 Oct 2008 16:36:16 -0400, Gregory Hall wrote:

This is the safest homebuilt IMO.(VariEze ). The canard makes it foolproof.

http://video.google.com.au/videoplay...77166441&hl=en

No, I have flown a Velocity and a Cozy and they are far from foolproof,
stall the canard and find out.

In article
,
Alan Baker wrote:


Anyone who thinks an aircraft can be made "foolproof" is a fool who
shouldn't be flying.

Like Mignet and his Pou-du-Ciel (Flying Flea).

Everything going swimmingly, unless you manage to somehow get it
inverted.

At which point it becomes so stable that it would stooge about until it
ran out of fuel, no way to bring it upright again.

In article ,
"Gregory Hall" wrote:

France? I don't live in France. I built and used to fly a Rotec Rally 2B
many years ago. It was a tail dragger with a high wing and the motor was
mounted atop the win[g] with a pusher prop.

When I got it trimmed out correctly at cruise speeds I could lean forward in
the seat to nose it down and lean back in the seat to nose it up.

Sort of like a Taylorcraft or Cessna 140 or similar small aircraft.

Even as
well-balanced as it was at about half throttle, when the engine quit it
would pitch up immediately and drastically because the high engine placement

.... Placed the thrust line enough above the center of drag that adding
power caused a downward pitch moment, and reducing power resulted in a
upward pitch.

and pusher prop had enough leverage so that the proper trim at the tail
counteracted the nose down force of the engine and prop.

Which is what the horizontal stab/stabilator is for.

If you didn't
immediately push the stick way forward when the engine quit it was a matter
of seconds before it would nose up fast and stall and then you would have no
control at all from the stick until it fell for a while and the nose dropped
(thank god for that) so you could gain speed provided you had enough
altitude to get control of it again. But it didn't glide too well being a
single surface wing with wire bracing. Perhaps 2:1 glide ratio. But it was
easy to land with no power but you had to come in hot and steep and at the
last second pull back on the stick and flare it.

It looks to me like the Legacy would act pretty much the same if the engine
quit.

Except for the Legacy not incorporating those design elements that
result in the pitch/power response of the Rotec Rally. The Rally needs a
lot of upward pitch dialed in for level cruise (which ought to be
contributing a lot of drag as an added bonus), giving you some nasty
response to losing power.

In particular, both thrust and drag components in the Legacy are much
closer in alignment, resulting in much less pitch change when power
changes.

The two aircraft behave very differently in many aspects, and the Legacy
not much at all as you've asserted.

Gregory Hall wrote:

I think it makes good sense. Look at the size of that engine up front. Looks
like a P-51 Mustang for pity sake. When you're being pulled along by that
big prop and heavy, powerful engine it pulls the nose of the aircraft down.
The horizontal stabilizers have to counteract this force by putting an
upward force on the nose by pushing the tail down. If and when the engine
suddenly dies the aircraft will pitch up suddenly and since the size of the
stabilizers are so puny they might easily stall and be unable to counteract
the upward pitch at the nose resulting in a tail down death spiral.


Good try, Greg, but there is so much that you have left out, or just
have plane wrong (yuk! yuk!). I'll just point out one thing that I
haven't seen anyone else mention.

Engine offset.

How an airplane behaves power-on vs. power-off can be be radically
modified with a few shims that will shift the direction the engine is
pulling. Left to right. Up to down. The numbers will be specified
with high accuracy in a set of plans. The Dyke Delta has 2/3 degree
upthrust. When you apply power it pulls the nose up. Drop power and so
does the nose. Makes for a more stable speed. There is no way you
could ever get those details from a picture over the internet.

Alan Baker wrote:
snip

Anyone who thinks an aircraft can be made "foolproof" is a fool who
shouldn't be flying.


When someone invents something foolproof someone else invents a
better fool.

Dan, U.S. Air Force, retired

"Steve Hix" wrote
Like Mignet and his Pou-du-Ciel (Flying Flea).

Everything going swimmingly, unless you manage to somehow get it
inverted.

At which point it becomes so stable that it would stooge about until it
ran out of fuel, no way to bring it upright again.

How about half of an outside loop?
--
Jim in NC

Gregory Hall wrote:

This is the safest homebuilt IMO.(VariEze ). The canard makes it foolproof.

If that were the case, the Velocity would have a better safety record
than the Lancair family. Based on my statistics from 1999 through 2006,
it doesn't... the Velocity has about a 20% higher accident rate. In
fact, the Velocity has a rate almost three TIMES higher that of the RV
fleet. Which isn't doesn't use canards, either.

The difference in fleet size does affect the statistics, of course....

Ron Wanttaja