Newsletter# 61 / April 1998
3/4/98
Dear Nat,
I have the same 3-blade Performance prop that you list in the
newsletter, but with an 8 inch prop extension. Maybe that is part of the reason my plane
is so quiet. I took sound measurements again yesterday and got 92 db (full throttle at
5,000 ft.) Based on what I have been reading lately, my plane is several db quieter than
normal. When I take other pilots for rides, the first thing they notice is the fantastic
visibility, the second thing they notice is how smooth and quiet it is. Of course the
Cessna pilots are totally green when they look at the airspeed indicator!
Thanks for the great design! I hope to see you and Shirley at Oshkosh
and then Copper State. I wanted to go to Lakeland, but it looks like I won't be able to
get off work.
Mark Beduhn
Cozy IV N494CZ
Newsletter# 61 / April 1998
12/2/97
Dear Nat & Shirley,
I am sorry for not writing sooner, but I am enjoying flying my Cozy
Mark IV so much I don't want anything to interfere! I am happy to report that on 4/3/97,
my Cozy Mark IV, N55CR made its first flight. When I got out onto the runway to do my high
speed taxi test, everything felt so good, that I took off and made my first flight. The
flight lasted for forty five minutes and I went up to an altitude of 6,000 feet above the
airport. The landing was very smooth, and the plane handled exactly as advertised. My
aircraft has a 0 timed 0-360 Lycoming and a 3 blade Performance prop, all electric trim
and landing brake and gear. I brought a cowhide home from Sun ‘n 'n and hand sewed
the taupe leather interior. The instrument panel has carbon fiber overlays and full
instrumentation including a stereo system. To date, we have 150 hours on the plane (with
no problems so far) and have taken trips to Rough River Kentucky, Georgia, Maryland and
Florida. My top speed thus far has been a very fast 216 mph at 8,000 feet. We are
extremely pleased with both the plans and the finished product. If anyone comes to this
area and would like to take a flight, I would be happy to show off the plane. Thank you
again Nat, for such an excellent aircraft.
Chris Scida
Rocky Point, NY
Newsletter# 61 / April 1998
12/21/97
Dear Nat,
Cozy N171BH, now with flight test and FAA signoff complete, has 46
hours on it. The interior is being sewn up, and spinner and wheelpants will come next. I
plan to attack the fly-in circuit next year as my work schedule allows. I can't wait.
Brian Heinitz
Roseville, CA
Newsletter# 61 / April 1998
1/20/98
Dear Nat,
Happy new year! After reading the flying qualities report on the
Velocity, along with the follow up article "Rock & Roll" by Ed Kolano in the
January 1998 issue of Sport Aviation, I decided to do some more testing on my Cozy.
In summary, the flying qualities report found that in the landing
configuration at 90 KIAS, the Velocity has a strong Dutch roll "interfering with the
airplane’s roll rate during aileron-only rolls from 30 degree right wing down to 30
degrees left wing down." With full left aileron applied, the Velocity begins to roll
as it should, but a strong adverse yaw causes enough sideslip to roll the airplane against
the direction of the aileron input. So a yaw-roll oscillation occurs, fighting the desired
roll input and turn, resulting in some pretty sloppy, and annoying flying. Now, any normal
pilot would have applied coordinated rudder and the messy wing rock and nose wag would
have been avoided, thereby keeping your passengers from getting sick! But I couldn't wait
to test for this on my Cozy.
But due to El Nino, I had to wait. In my flight test program, I tested
for Dutch roll, adverse yaw, and checked dynamic roll response. My notes show that all
Dutch roll attempts dampened within 4 cycles (max allowable is 6). Yaw tested as neither
adverse or proverse. Dynamic roll response revealed no roll hesitation, with proper
balance between degree of stick input and roll rate. In short, my Cozy passed these and
other stability and control tests with flying colors. But did I miss something? The Sport
Aviation article got me wondering.
Today the rains finally took a break and unbelievably: no fog! So I
launched. I set N171BH up in the landing configuration and tested at speeds between 80 and
100 KIAS. Starting with an established 30 or 45 degree left or right bank, I applied
aileron-only full stick inputs rolling out of the bank, through level flight, and through
an equal bank in the opposite direction. All that worry for nothing! My Cozy exhibits none
of the strong Dutch rolling found in the Velocity article. Adverse yaw was very small to
none at all. There wasn't even a hint of Dutch roll. Naturally, roll rate was slower at
lower than at higher speeds, and I didn't time it. But each attempt resulted in a smooth
and steady and continuous roll from the starting point through wings level to the opposite
side. I estimate the total time for each maneuver was between 4 to 6 seconds, depending on
starting bank angle and airspeed. Then, once coordinated rudder is added (don't need much)
my Cozy handles very well in the pattern.
One thing I haven't tried yet is to seal the gap between the top wing
skin and aileron with tape over the hinge line. A friend of mine says it makes the
ailerons noticeably more responsive in his Varieze. I plan to try it on my airplane. A
faster roll rate at low pattern speeds could be useful if I ever get wrapped in somebody's
wake at a busy airport. Meanwhile, I'm very pleased with the flying qualities of the Cozy.
Now, if I could just get a set of wheel pants and a spinner installed.
Brian Heinitz
Roseville, CA
Editor: Brian has a 3-place. The better directional stability he
refers to at low speeds could be due to the lower winglets, which the Velocity may not
have had. Also, roll response is faster on the Mark IV, because the ailerons are farther
outboard due to the 2 ft. greater wingspan.
Newsletter# 61 / April 1998
2/4/98
Dear Nat,
Just a note to let you know how COZY 267 CZ is doing. I installed an
0-320 about 8 months ago and after a few months of testing and debugging, I'm seeing about
a 300 ft. shorter take off with a climb of 1500 to 1800 fpm. The top speed has increased
about 10 kts. This is a much better performance over the 135 hp 0-290
As per our last phone conversation, have you heard if cutting the
exhaust pipes off at an angle has any advantages? (Editor: No) Hope to see you at
Sun 'n Fun in the spring!
John Ashe
Durham, NC
1/2/98
Dear Nat,
I recently began flying Cozy aircraft 98RH which was built by my
father, Ray Hart of Williamsburg, VA. Along with the aircraft he gave me a library of past
issues of your newsletter, which I have really enjoyed reading and found very informative.
I am amazed at how much there is to learn about these aircraft. I look forward to
receiving future copies of the newsletter and flying your design. While I am still
learning about the aircraft, so far it is a great flying machine!!
Terry Hart
Lawrenceville GA
Newsletter# 63 / October 1998
6/18/98
Dear Nat,
I cannot believe that I have over 500 hours on my Cozy III. I have flown it from
Maryland to northern Canada, down to the Grand Turk islands, and then as far west as the
Grand Canyon. But it got a little fat over the years and I found that I was only climbing
at 400 fpm at 10,000 ft. This would be great for a GA plane but not for one of ours. So,
as we discussed at S&F, I went out and got an O-320 B2B which I am rebuilding. I
bought an engine that had been lying around a parts dealers storage shed for years for
$1500. It had no logs, but when I broke it open it had very little rust or wear. The crank
flange was bent too badly so I had to get a reconditioned crank.
Your builders who are in the market for an engine should know that the crank is the
most expensive part of the engine. New ones cost over $4000. They should not get an
"experimental" crank as they are not up to our needs. Sure we are pushing a
wooden prop, but with the prop extensions we are using, you would get a severe gyroscopic
wobble with only a little deformation of the crank and/or flange.
I have just gotten all the parts back yellow tagged, so I will soon start to rebuild
the engine. I have a very experienced AI who is looking over my shoulder (yes, there are
under-qualified AI's). Rebuilding the engine is almost as much fun as building the plane.
Will let you know if I run into anything unique.
Did some interesting air flow work with oil on the wings and VGs. If you would like me
to write something up, let me know.
I am looking for a used prop for the 0-320, climb or cruise, it does not matter. After
I use it this summer and fall I plan to use the wooden prop as a core for a composite lay
up this winter. I want a light but stronger prop than I have been flying with. Say hello
to Shirley from Janie and me.
Ken Brimmer
Bowie, MD
Newsletter# 63 / October 1998
9/10/98
Hello Nat,
I have been enjoying the heck out of the Cozy III. Thanks once again for creating this
bird. Outside air temps are starting to drop, today only 91, hope for 65 Saturday morning.
I can't wait to try the plane out at these temps.
Ken Reiter
Dallas, TX