REFLECTOR:Pure Jet Velocity KL

Jim Sower reflector@tvbf.org
Sun, 08 Feb 2004 19:17:54 -0600


--------------40B31615524A4DECB502468F
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable

<... much more worried about losing the elevator or ailerons due to flutt=
er ...>
That's a very real possibility.

<... operation of the aircraft at say 30k feet with pressure oxy system a=
s long as they do not exceed the current VNE indicated- which would be a =
really good ground speed ...>
That would pretty much guarantee flutter since it's a function of TRUE ai=
rspeed (among other things).

Besides pressure O2 at 30k, you need to watch out for the bends .... Jim =
S.


alex157@direcway.com wrote:

> I agree with Richards asssessment of the very real danger of running th=
e velocity airframe beyond it's designed VNE, although even the velocity =
has significant drag at those high speeds (drag increases as the sqare of=
 speed - re: accidentally increasing the speed in a dive) I did not see a=
nything on the Jet site that suggested that they were going to run past t=
he published VNE (maybe I missed that)- I think that the customer just wa=
nts to have the "cool" factor of running a jet back there- nothing wrong =
with decreasing the T.O. distance by 25-40%, and allowing operation of th=
e aircraft at say 30k feet with pressure oxy system as long as they do no=
t exceed the current VNE indicated- which would be a really good ground s=
peed at that altitude.  I would be much more worried about losing the ele=
vator or ailerons due to flutter than stalling the canard due to the shoc=
k wave - I really don't think that the airframe could be pushed to that s=
peed without loosing at least one of the co
> ntrol surfaces.
>
> ----- Original Message -----
> From: Greg Poole <gpoole@zeta.org.au>
> Date: Saturday, February 7, 2004 10:49 pm
> Subject: Re: REFLECTOR:Pure Jet Velocity KL
>
> > Quite sobering comment Richard!
> >
> > Greg in learning mode.
> > Sydney.
> >
> > ----- Original Message -----
> > From: <richard@riley.net>
> > To: <reflector@tvbf.org>
> > Sent: Sunday, February 08, 2004 11:55 AM
> > Subject: Re: REFLECTOR:Pure Jet Velocity KL
> >
> >
> > > I have said this before, and said it directly to some of the
> > people who
> > are
> > > building these airplanes.
> > >
> > > A jet canard is a fatal accident just waiting for someone to
> > open up the
> > > throttle.
> > >
> > > The canard will mach stall well before the main wing.  John
> > Roncz believes
> > > that the 1145MS will hit it's critical mach at  somewhere
> > between .55 -
> > .65
> > > mach.  The GU and the Velocity canard are probably in the same
> > > neighborhood.  At 25k that's only 380 mph.  At 700 lbs thrust, thes=
e
> > > converted T-55's can get that in in level flight.  Even if not,
> > withoutthe
> > > drag of a prop and some residual thrust at idle, you could start
> > out at
> > 300
> > > mph at altitude, pull back the throttle, drop the nose and be
> > through your
> > > critical mach in a few seconds.
> > >
> > > If the canard mach stalls, you're dead.  There will be no
> > possible way to
> > > recover.  Aerodynamically, it will be as if the canard has come
> > off the
> > > airplane.  The elevators will have no effect at all.  Putting
> > out the
> > > landing brake and gear won't do nearly enough.  You'll just go
> > faster and
> > > faster until something flutters to destruction or you hit the
> > ground.>
> > > I can't say this clearly enough.  This is not something you can
> > sneak up
> > > on, stretch the envelope and back off from.  This is a sudden,
> > > unrecoverable, unpredictable, 100% lethal failure mode.
> > >
> > > Here's a primmer
> > >
> > > http://142.26.194.131/aerodynamics1/High-Speed/Page2c.html
> > >
> > > The important 'graph -
> > >
> > > "The second form of drag, due to the shockwave is unique to the
> > normal> shock wave. The shock wave tends to stop the boundary
> > layer, causing the
> > > flow to separate and thereby producing effects almost the same
> > as a
> > > stall.  Thus, the term "Mach Stall" has been coined.
> > >
> > > The diagram to the left shows a wing with the lift being
> > disrupted and the
> > > drag greatly increased by a Mach Stall. In a mach stall the aircraf=
t
> > > experiences a loss of lift, increase in drag and usually a
> > tendency to
> > > pitch nose down. In other words it has most of the same symptoms
> > as a low
> > > speed stall except the angle of attack is quite small and the
> > TAS is very
> > > high."
> > >
> > > So, you're flying along very fast.  How fast?  Hard to say, but
> > above .5
> > > mach.  You decide you're going to drop a couple of hundred feet
> > to dip
> > > below some clouds.  As you do so you go just a LITTLE bit faster.
> > >
> > > Your canard stalls.  Just like it would if you were going very
> > slowly, at
> > a
> > > high angle of attack.  What happens?  The nose drops.  You go
> > faster.  The
> > > stall remains.  The nose drops more.  You go faster.  The stall
> > remains.>
> > > Eventually you tie the low altitude record.
> > >
> > > The canard we're flying couldn't be worse for delaying the onset
> > of shock
> > > waves.  It's a thick section, narrow chord, and with no sweep at
> > all.  The
> > > main wings are actually not bad, well swept, wide chord, not too
> > > thick.  But, as with the low speed stall, it's the canard that
> > matters.>
> > > The Vne of these airplanes should be no more than 300 mph.  And
> > it should
> > > be considered a Vinstantdeath.
> > >
> > >
> > >
> > > At 03:10 PM 2/6/04 -0500, you wrote:
> > > >Hi Group,
> > > >
> > > >If you're interested in seeing a pure jet Velocity XL being
> > built, go to
> > > >www.x-jets.com. Click on "projects" then click on "Velocity Jets."=

> > > >
> > > >It's being built at 44N Skyachers in New York.  Andreas has also
> > made
> > > >some remarkable mod's to the control and heating systems. Check
> > them> >out
> > > >
> > > >Mike W.
> > >
> > > _______________________________________________
> > > To change your email address, visit
> > http://www.tvbf.org/mailman/listinfo/reflector
> > >
> > > Visit the gallery!  www.tvbf.org/gallery
> > > user:pw =3D tvbf:jamaicangoose
> > > Check new archives: www.tvbf.org/pipermail
> > > Check old archives:
> > http://www.tvbf.org/archives/velocity/maillist.html
> >
> > _______________________________________________
> > To change your email address, visit
> > http://www.tvbf.org/mailman/listinfo/reflector
> > Visit the gallery!  www.tvbf.org/gallery
> > user:pw =3D tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives:
> > http://www.tvbf.org/archives/velocity/maillist.html
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinf=
o/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw =3D tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html=


--
Jim Sower ... Destiny's Plaything
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T


--------------40B31615524A4DECB502468F
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
&lt;... much more worried about losing the elevator or ailerons due to
flutter ...>
<br>That's a very real possibility.
<p>&lt;... operation of the aircraft at say 30k feet with pressure oxy
system as long as they do not exceed the current VNE indicated- which would
be a really good ground speed ...>
<br>That would pretty much <b>guarantee</b> flutter since it's a function
of TRUE airspeed (among other things).
<p>Besides pressure O2 at 30k, you need to watch out for the bends ....
Jim S.
<br>&nbsp;
<p>alex157@direcway.com wrote:
<blockquote TYPE=CITE>I agree with Richards asssessment of the very real
danger of running the velocity airframe beyond it's designed VNE, although
even the velocity has significant drag at those high speeds (drag increases
as the sqare of speed - re: accidentally increasing the speed in a dive)
I did not see anything on the Jet site that suggested that they were going
to run past the published VNE (maybe I missed that)- I think that the customer
just wants to have the "cool" factor of running a jet back there- nothing
wrong with decreasing the T.O. distance by 25-40%, and allowing operation
of the aircraft at say 30k feet with pressure oxy system as long as they
do not exceed the current VNE indicated- which would be a really good ground
speed at that altitude.&nbsp; I would be much more worried about losing
the elevator or ailerons due to flutter than stalling the canard due to
the shock wave - I really don't think that the airframe could be pushed
to that speed without loosing at least one of the co
<br>ntrol surfaces.
<p>----- Original Message -----
<br>From: Greg Poole &lt;gpoole@zeta.org.au>
<br>Date: Saturday, February 7, 2004 10:49 pm
<br>Subject: Re: REFLECTOR:Pure Jet Velocity KL
<p>> Quite sobering comment Richard!
<br>>
<br>> Greg in learning mode.
<br>> Sydney.
<br>>
<br>> ----- Original Message -----
<br>> From: &lt;richard@riley.net>
<br>> To: &lt;reflector@tvbf.org>
<br>> Sent: Sunday, February 08, 2004 11:55 AM
<br>> Subject: Re: REFLECTOR:Pure Jet Velocity KL
<br>>
<br>>
<br>> > I have said this before, and said it directly to some of the
<br>> people who
<br>> are
<br>> > building these airplanes.
<br>> >
<br>> > A jet canard is a fatal accident just waiting for someone to
<br>> open up the
<br>> > throttle.
<br>> >
<br>> > The canard will mach stall well before the main wing.&nbsp; John
<br>> Roncz believes
<br>> > that the 1145MS will hit it's critical mach at&nbsp; somewhere
<br>> between .55 -
<br>> .65
<br>> > mach.&nbsp; The GU and the Velocity canard are probably in the
same
<br>> > neighborhood.&nbsp; At 25k that's only 380 mph.&nbsp; At 700 lbs
thrust, these
<br>> > converted T-55's can get that in in level flight.&nbsp; Even if
not,
<br>> withoutthe
<br>> > drag of a prop and some residual thrust at idle, you could start
<br>> out at
<br>> 300
<br>> > mph at altitude, pull back the throttle, drop the nose and be
<br>> through your
<br>> > critical mach in a few seconds.
<br>> >
<br>> > If the canard mach stalls, you're dead.&nbsp; There will be no
<br>> possible way to
<br>> > recover.&nbsp; Aerodynamically, it will be as if the canard has
come
<br>> off the
<br>> > airplane.&nbsp; The elevators will have no effect at all.&nbsp;
Putting
<br>> out the
<br>> > landing brake and gear won't do nearly enough.&nbsp; You'll just
go
<br>> faster and
<br>> > faster until something flutters to destruction or you hit the
<br>> ground.>
<br>> > I can't say this clearly enough.&nbsp; This is not something you
can
<br>> sneak up
<br>> > on, stretch the envelope and back off from.&nbsp; This is a sudden,
<br>> > unrecoverable, unpredictable, 100% lethal failure mode.
<br>> >
<br>> > Here's a primmer
<br>> >
<br>> > <a href="http://142.26.194.131/aerodynamics1/High-Speed/Page2c.html">http://142.26.194.131/aerodynamics1/High-Speed/Page2c.html</a>
<br>> >
<br>> > The important 'graph -
<br>> >
<br>> > "The second form of drag, due to the shockwave is unique to the
<br>> normal> shock wave. The shock wave tends to stop the boundary
<br>> layer, causing the
<br>> > flow to separate and thereby producing effects almost the same
<br>> as a
<br>> > stall.&nbsp; Thus, the term "Mach Stall" has been coined.
<br>> >
<br>> > The diagram to the left shows a wing with the lift being
<br>> disrupted and the
<br>> > drag greatly increased by a Mach Stall. In a mach stall the aircraft
<br>> > experiences a loss of lift, increase in drag and usually a
<br>> tendency to
<br>> > pitch nose down. In other words it has most of the same symptoms
<br>> as a low
<br>> > speed stall except the angle of attack is quite small and the
<br>> TAS is very
<br>> > high."
<br>> >
<br>> > So, you're flying along very fast.&nbsp; How fast?&nbsp; Hard to
say, but
<br>> above .5
<br>> > mach.&nbsp; You decide you're going to drop a couple of hundred
feet
<br>> to dip
<br>> > below some clouds.&nbsp; As you do so you go just a LITTLE bit
faster.
<br>> >
<br>> > Your canard stalls.&nbsp; Just like it would if you were going
very
<br>> slowly, at
<br>> a
<br>> > high angle of attack.&nbsp; What happens?&nbsp; The nose drops.&nbsp;
You go
<br>> faster.&nbsp; The
<br>> > stall remains.&nbsp; The nose drops more.&nbsp; You go faster.&nbsp;
The stall
<br>> remains.>
<br>> > Eventually you tie the low altitude record.
<br>> >
<br>> > The canard we're flying couldn't be worse for delaying the onset
<br>> of shock
<br>> > waves.&nbsp; It's a thick section, narrow chord, and with no sweep
at
<br>> all.&nbsp; The
<br>> > main wings are actually not bad, well swept, wide chord, not too
<br>> > thick.&nbsp; But, as with the low speed stall, it's the canard
that
<br>> matters.>
<br>> > The Vne of these airplanes should be no more than 300 mph.&nbsp;
And
<br>> it should
<br>> > be considered a Vinstantdeath.
<br>> >
<br>> >
<br>> >
<br>> > At 03:10 PM 2/6/04 -0500, you wrote:
<br>> > >Hi Group,
<br>> > >
<br>> > >If you're interested in seeing a pure jet Velocity XL being
<br>> built, go to
<br>> > >www.x-jets.com. Click on "projects" then click on "Velocity Jets."
<br>> > >
<br>> > >It's being built at 44N Skyachers in New York.&nbsp; Andreas has
also
<br>> made
<br>> > >some remarkable mod's to the control and heating systems. Check
<br>> them> >out
<br>> > >
<br>> > >Mike W.
<br>> >
<br>> > _______________________________________________
<br>> > To change your email address, visit
<br>> <a href="http://www.tvbf.org/mailman/listinfo/reflector">http://www.tvbf.org/mailman/listinfo/reflector</a>
<br>> >
<br>> > Visit the gallery!&nbsp; www.tvbf.org/gallery
<br>> > user:pw = tvbf:jamaicangoose
<br>> > Check new archives: www.tvbf.org/pipermail
<br>> > Check old archives:
<br>> <a href="http://www.tvbf.org/archives/velocity/maillist.html">http://www.tvbf.org/archives/velocity/maillist.html</a>
<br>>
<br>> _______________________________________________
<br>> To change your email address, visit
<br>> <a href="http://www.tvbf.org/mailman/listinfo/reflector">http://www.tvbf.org/mailman/listinfo/reflector</a>
<br>> Visit the gallery!&nbsp; www.tvbf.org/gallery
<br>> user:pw = tvbf:jamaicangoose
<br>> Check new archives: www.tvbf.org/pipermail
<br>> Check old archives:
<br>> <a href="http://www.tvbf.org/archives/velocity/maillist.html">http://www.tvbf.org/archives/velocity/maillist.html</a>
<p>_______________________________________________
<br>To change your email address, visit <a href="http://www.tvbf.org/mailman/listinfo/reflector">http://www.tvbf.org/mailman/listinfo/reflector</a>
<p>Visit the gallery!&nbsp; www.tvbf.org/gallery
<br>user:pw = tvbf:jamaicangoose
<br>Check new archives: www.tvbf.org/pipermail
<br>Check old archives: <a href="http://www.tvbf.org/archives/velocity/maillist.html">http://www.tvbf.org/archives/velocity/maillist.html</a></blockquote>

<p>--
<br>Jim Sower ... Destiny's Plaything
<br>Crossville, TN; Chapter 5
<br>Long-EZ N83RT, Velocity N4095T
<br>&nbsp;</html>

--------------40B31615524A4DECB502468F--