Aeronautical Engineering Help needed

BllFs6 wrote:
isnt that like trying to compare a high mileage compact car to a dragster?

I don't know of any dragsters that have to pull 6gs in a corner.
Induced drag is an issue with Reno racers. When I was working with
Randy Howell, when he owned Madder Maxxx, I worked on convincing him to
fly a looser course, to lower the loading in the corners. He agreed to
go out in practice and fly three laps tight around the pylons and three
laps loose around the pylons. By his own admission, he turned much
faster laps flying loose. This was exactly what I had predicted using
my race course simulation program (which is NOT a CFD program!).

Dave

Some more data on racing.

I flew model aircraft in races for a number of years. Top speed in
class was about 100 mph.

When you came up to a pylon and cut the corner tight and pulled high
G's you bled off airspeed.

We used fixed pitch props and you had two choices. With a flat pitch
prop you had lots of thrust in turn and didn't lose very much
airspeed. and would accelerate back to top speed for that prop very
fast.

If you used a high pitch prop you lost speed in the turn and slowly
accelerated to top speed on the straight away however you had a high
flat out top speed with the high pitch prop and would overtake the
flat pitch prop on the straight away. Next pylon the flat pitch prop
would turn tighter and not lose as much airspeed and take the lead
again.

Propping the engine correctly let you win races. Engine power varied
with moisture and temp so each day and sometimes each race as the day
wore on required a different pitched prop to max out the capability of
your bird.

Am sure the Reno boys have a more fancy method than we used but I
learned a lot flying in competition that could be applied directly to
GA and up aircraft.

Big John


On Wed, 07 Jan 2004 11:03:00 -0800, David Lednicer
wrote:

BllFs6 wrote:
isnt that like trying to compare a high mileage compact car to a dragster?

I don't know of any dragsters that have to pull 6gs in a corner.
Induced drag is an issue with Reno racers. When I was working with
Randy Howell, when he owned Madder Maxxx, I worked on convincing him to
fly a looser course, to lower the loading in the corners. He agreed to
go out in practice and fly three laps tight around the pylons and three
laps loose around the pylons. By his own admission, he turned much
faster laps flying loose. This was exactly what I had predicted using
my race course simulation program (which is NOT a CFD program!).

Ed Wischmeyer wrote:

Canard aircraft hold several FAI recognized world records in altitude,
speed, and range. A canard holds the CAFE Challenge efficiency record
and will likely have a lock on it for years to come. Canards have
been flown to numerous first-place race wins and high race placings in
competitions against non-canard designs.

That's not engineering analysis, that rhetoric trying to impress and to
win an argument. Can we go back to lift distributions, please?


When engineering analysis doesn't jibe with reality, I choose reality
as the final arbiter. Your "rhetoric trying to impress" remark was
not only rude, but reveals that you missed the very point.

David O -- http://www.AirplaneZone.com

David Lednicer wrote:

1) I purposely said "long range", not range. For long range, you do
slow down to near L/D max.

Your response to Richard's claim that canards have good range began
with, "I've got to disagree with your assertion that canards are good
for range." Others can judge for themselves whether Richard was
talking about cruise range or about range at max L/D. You already
know my take on both Richard's meaning and your response.

2) For cruise range like you talk about, you're right, the Long EZ is
actually better than an RV-6. This is due to the Long EZ's low zero
lift drag and reasonable induced drag efficiency.

Q.E.D.

3) Calling me "Pilgrim" is technically incorrect. My mother's family
came to the Puritan Bay Colony ten years (1632) after the Mayflower
landed (1622).

Relax, cowboy, it's just an expression.

3) Your average speed for Voyager is incorrect. They covered 24,986.73
statute miles in 216 hours, 3 minutes and 44 seconds. This works out to
115.6 mph ground speed. I have been told that this is a pretty good
approximation of the average true airspeed.

Your 115.6 mph is the FAI accredited average ground speed based on the
FAI accredited distance flown. It is not, however, the actual average
ground speed flown. The 122 mph figure I cited is the actual average
ground speed flown based on the actual distance flown (26,366 statute
miles).

Oh, so only Burt knows anything about designing airplanes.

No, but with all due respect, I would better trust Burt on this
particular subject.

David O -- http://www.AirplaneZone.com

David Lednicer wrote:

How about dropping the ax you are grinding and learning some basic aero?
The "overall elliptical sum" is NOT a false premise. It is also a
"CFD-based musing". This dates back to the 1920s and people like
Ludwing Prandtl and Max Munk.

Those studies were not of, did not consider, and do not apply to
canard aircraft with winglets.

Your arguments are ancedotal. Mine are engineering based.

The correct term for an argument based upon verifiable real-world data
is "empirical", not "anecdotal". My argument was deliberately
empirical. When engineering analysis doesn't jibe with reality, I
choose reality as the final arbiter.

Show me a canard Reno racer that has ever won a race.

To my knowledge, the highest placed canard aircraft (*) at Reno was
David Ronnerberg's Berkut which finished second place among six
Glasairs in 1999. The first place Glasair III was 9.4 mph faster than
the Berkut and the Berkut was 11.9 mph faster than the third place
Glasair III. Although the Berkut did not take first place, its second
place showing remains a valid example of a high canard placing among
non-canard aircraft. Thanks for helping to reinforce my point.

David O -- http://www.AirplaneZone.com

* The purpose-built screamer "Pushy Galore" had a small canard but
also a T-tail.

RU ok wrote:

Hell, I even like canards....

Me too. I particularly enjoy stir-fry mallard. Wait, the water fowl
thread already happened!

David "fashionably late" O -- http://www.AirplaneZone.com

David O wrote:
Those studies were not of, did not consider, and do not apply to
canard aircraft with winglets.

These studies apply to ANY arrangement of lifting surfaces. Even your
idol Burt Rutan uses them.

And my family met Columbus at the dock. So what?

Jim



David O
shared these priceless pearls of wisdom:

-David Lednicer wrote:

-
-3) Calling me "Pilgrim" is technically incorrect. My mother's family
-came to the Puritan Bay Colony ten years (1632) after the Mayflower
-landed (1622).
-
-Relax, cowboy, it's just an expression.




Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Richard Riley wrote:

And, just for the record, Dave Ronneberg few the airplane at Reno. But I paid
for it. It was mine.

Well then, congrats on the second place showing.

David O -- http://www.AirplaneZone.com

On Thu, 08 Jan 2004 22:43:42 -0500, David O
wrote:

:Richard Riley wrote:
:
:And, just for the record, Dave Ronneberg few the airplane at Reno. But I paid
:for it. It was mine.
:
:Well then, congrats on the second place showing.

Thanks. It's faster now, I'll do better next time.