Cozy IV vs. Velocity
Jeff Rosson
Anyone familiar with some of the differences between the Cozy and
Velocity? I know the Cozy is build from plans vs. build from kit,
but what about flying qualities, building times, safety, stall speed,
etc. This Thursday (Aug 17) I am taking a demo ride in a Velocity,
but I know of no one in my area (Melbourne, FL) with a Cozy. Also,
how easy is it to work with fiberglass and to make foam cores?
Thanks for any insight.
Jeff Rosson
10246...@compuserve.com
Marc Zeitlin
I guess this is going to come up every once in a while. I'm building a
COZY MKIV. You can check out my project, as well as a wealth of COZY
info, at:
http://www.ultranet.com/~marcz/cozy_mkIV/
you can check out George Venkatesh's Velocity project at:
http://www.tacoma.net/~venky/Velocity/
There was a previous string that a few people replied to on this topic
which you may be able to access (depending upon how long CS archives
newsgroups). If you have any questions, please feel free to ask via
email. (I should write a FAQ on this question :-).
--
_______________________________________________________________________
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Kirk Lindberg
> Hello,
> Anyone familiar with some of the differences between the Cozy and
> Velocity? I know the Cozy is build from plans vs. build from kit,
> but what about flying qualities, building times, safety, stall speed,
> etc.
I have been flying my Velocity for over a year now and its a great
airplane (even won an award with it at Oshkosh this year!!). I think all
the canard designs (EZE, Cozy and Velocity) are safe airplanes with good
flying qualities. Nat Puffer is a friend of mine and had the Cozy IV been
available when I started building I would have considered it.
The advantages as I see it for the Velocity are:
1. More choices - fixed gear or retract, standard or 173 wing,
standard or Elite doors.
2. More room inside
3. Faster build time
The advantages for the Cozy:
1. Less cost
2. Smaller engine (180 vs 200hp)
Both Nat and Velocity give excellent support, so the decision is really
based on criteria that you have to establish.
--
Kirk Lindberg
Velocity N94KL | _ |
kalin...@mmm.com |--------(.)--------|
St.Paul, MN O o O
HighPlane
Cozy, and finally decided to build ... an AeroCanard, a new kit that's
virtually identical to the Cozy Mk IV in design (tho slightlly roomier
inside) ... and very much Velocity in build time and techniques. It's
new--the prototype flew to Oshkosh in primer this year--but the company
(AeroCad of Yadkinville, NC) has been prefabbing parts and subassemblies
for Cozy builders and others for years (including, I think, a set of wings
for Dick Rutan's Berkut). The price is a little more than for the Cozy,
but a bit less than Velocity. So far, largely on word of mouth, they've
sold 10 fuselage tubs to Cozy builders who wanted to convert, plus another
8 complete AeroCanard kits (mine's # 3). Their phone # is 910-961-2238.
Let me know if you want me info.
Jon Jefferson, 615-524-3601
HighPlane
Frogcat
at rest. Its and awesome sight to see a line of Cozys "bowing" to a
Velocity!
--- An obviously biased Velocity builder
Carl Stevens (e00680)
Having had a chance to view a Velocity project I can describe my impression
in one word.
Heavy.
--
Carl Stevens _ Long EZ N223MM
cste...@ladc.lockheed.com _\_/^\_/_
My opinions are my own. _____/_/_/|\_\_\_____ 4 Young Eagles Flown
Tim Busch
says...
>
>In <41al98$r...@butch.lmsc.lockheed.com> cste...@butch.lmsc (Carl
>Stevens (e00680)) writes:
>
>> Having had a chance to view a Velocity project I can describe my
>> impression in one word.
>>
>> Heavy.
>
>Mark IV. Consequently, it will be somewhat heavier, as well as more
>comfortable. (And the new Elite option makes it a whole lot easier to
>get into.) Empty weight on a properly built Velocity Standard is under
>1,300 lbs (even with a decent IFR panel, but without a fancy leather
>interior), with a gross weight of 2,250. (The Velocity 173 weighs about
>50-75 lbs more, with a 150 lb higher gross weight.) The original Cozy
>Mark IV prototype had an empty weight of 1,070 pounds; I don't know
>what the current ones weigh. For me, the extra room (and easier
>construction) was well worth the 200 lbs.
>
>Chuck Caldarale PP-ASEL/IA | _ |
>Minneapolis, MN Building Velocity N828CL |------( )------|
>(Establishing a relationship with my sanding block) O o O
>
Did they ever solve the 'deep stall' problem with the Velocity?
If so, how?
Tim
Chuck Caldarale
Busch) writes:
> Did they ever solve the 'deep stall' problem with the Velocity?
> If so, how?
Yes - this is one of the questions answered in the forthcoming Velocity
FAQ, which I promise to finish Real Soon Now. The deep stall phenomenon
is not unique to the Velocity, having been subsequently demonstrated
(both expectedly and un-) in Cozys, Long-EZs, and Vari-EZs, as well as
more traditionally configured planes. Here's the info from the FAQ:
3. What is this “deep stall” I keep hearing about?
[This information was obtained from the Duane Swing, the newsletter,
and articles appearing in Sport Aviation and Kitplanes.]
Deep stall is an aerodynamic stall condition that is unrecoverable
using normal control surface movement or power manipulation. It is not
unique to canard aircraft, having been demonstrated on numerous
occasions in planes varying from Cherokees to Learjets. However, it’s
notable in a canard plane because this aircraft configuration is
intended to be stall and spin proof (the canard is supposed to stall
before the main wing, thereby not allowing a deep stall to develop).
The first Velocity deep stall occurred in a brand new aircraft
apparently loaded such that the CG was behind the aft limit (no weight
and balance had been done), and without the vortilons installed. (A
vortilon is a sort-of stall fence mounted on the bottom leading edge of
the main wing.) After entering the deep stall from a high angle of
attack, the aircraft assumed a nearly flat attitude with a fairly low
sink rate and no significant forward motion. The plane pancaked into a
canal, with the pilot receiving only minor injuries and the plane
sustaining minor damage.
This accident prompted factory investigation of this unexpected
phenomenon. Using gap seals on the canard/elevator junction (don't try
this at home), a test pilot in Totally Orange reproduced the deep stall
situation, even to the point of riding the plane into the water
(Atlantic Ocean, this time). Although he was wearing a parachute, the
pilot chose to stay with the plane since the sink rate was less than
1,200 fpm - no injuries resulted, and he was picked up by the Coast
Guard a short time later. Totally Orange suffered no significant damage
during the “landing”, but did require some repair after being dragged
onto the beach (yes, Velocities do float).
After this, Dan Maher developed a couple of tools to help investigate
the problem and potential solutions. The first of these was a 210 lb
weight installed in Totally Orange that could be moved in flight to
alter the CG, and help bring the nose down if a deep stall should
occur. The second was an outdoor wind tunnel - a Velocity mounted on a
trailer in such a way that the aircraft could pivot up and down to
simulate any angle of attack desired while the trailer was being pulled
around the airport by a truck.
After testing various configurations on the trailer, the test pilot
again duplicated the deep stall in Totally Orange, this time being able
to recover without getting wet. The plane was then fitted with the fix
developed on the trailer, and reflown. The fix (60 inch leading edge
cuffs on the outboard end of each wing) cured the problem - as the
trailer tests indicated it would, and was promptly made available to
all the builders, at no charge. Since the cuffs did not exactly enhance
the appearance of the plane, Dan reworked the main wing, adding about
2.5 inches to the outboard chord, and modifying the outboard airfoil
slightly. As soon as it was ready, the new wing began shipping with all
subsequent kits.
Since the Velocity testing, deep stall problems have also been found in
certain EZs, as well as the Cozy Mark IV. The Cozy fix involved
requiring the use of the lower winglets (which some builders had been
leaving off), and a slightly shorter canard (causing it to stall
earlier). The Velocity fix did not measurably affect its performance.
One final installment in the deep stall saga hammered home the lesson
of not flying an aircraft outside of its envelope. This was a fatal
inverted stall, caused by a wake turbulence encounter with a 727 inside
the Orlando TCA (both aircraft were in contact with ATC). The accident
plane was the first kitbuilt Standard FG, modified by the builder,
without the outboard wing cuffs, and loaded 2.5 inches aft of the CG
limit. The plane went into an inverted deep stall, lost power, and with
the CG where it was, recovery was impossible. The plane had been
altered to carry more fuel by removing the aft fuel bulkhead, thus
extending the tank area rearwards to the main spar, and moving the CG
dangerously far aft. The factory had tried on numerous occasions to get
the builder to put it back. DON'T EVER, EVER MUCK WITH THE CG THIS
WAY!! Even a Cherokee or a C172 could not have recovered when loaded
like this.
- Chuck
HighPlane
were already built/flying, and redesigned the wing slightly to prevent the
problem on subsequent kits. I'm not an AE, so can't speak to the details;
somebody else??
HighPlane (Jon Jefferson, Higher Plane Communications, Knoxville, TN)
Bill Coleman AA4LR
(Tim Busch) wrote:
>
> Did they ever solve the 'deep stall' problem with the Velocity?
> If so, how?
First of all, there was never a "deep stall" problem in the Velocity as
originally designed. The only fatalities reported with a Velocity in the
deep stall condition were caused by an encounter with wake turbulence that
caused the fuel to displace rearward in the modified tanks. Bereft of
flying speed and out of CG range, an inverted deep stall ensued with fatal
results.
So, the problem was basically of margin over "deep stall". This was solved
in two ways:
1) For original Velocity wings, outboard cuffs were added to the main
wings to delay the onset of main wing stall.
2) For newer kits (and all 173 models), a new wing design with better
sections is used to delay onset of main wing stall. This "three piece"
wing has better stall characteristics than the cuffed wing.
Canard designs are extremely sensitive to CG positioning. Much of the
safety factor built-in to the design require the CG to stay in range.
Careful loading to ensure you are entirely inside the CG envelope is quite
important.
I find that the Velocity aircraft solution to improving deep stall margin
more acceptable than the Cozy Mark IV solution of hacking off Canard span.
Chopping the canard causes increases in takeoff and landing roll (due to
higher flying speeds) as well as lower climb rate and higher pitch buck
speeds (due to same).
The only other story I've heard of a deep stall condition happened with a
fellow flight testing his RG model. He entered a deep stall and managed to
escape by lowering the gear. Turns out his main wings LACKED VORTILONS!
Needless to say, he added the vortilons before he flew again.
--
Bill Coleman, AA4LR Mail: aa...@radio.org
Quote: "The same light shines on vineyards that makes deserts." -- Steve Hackett
Terry Schell;x3332
>Did they ever solve the 'deep stall' problem with the Velocity?
>If so, how?
>Tim
This is the proverbial "Did you ever stop beating your wife?"
question. The only Velocities the have had a "deep stall" (as far
as I know) had modified main wings.
I think there should be a law that you cannot call your plane a "XXXX"
if you make any changes to the airframe or aerodynamics that are
specifically contraindicated in the manual for that plane.
Terry Schell
(Just kidding about the law. The FAA would probably be in charge of
the enforcement.)