Johnson Flight Tests have been updated

Greg, you did a fine job of putting these articles up
and the effort is greatly appreciated. I read them all
and found useful information in all of them.

I was not putting down anyones pilot report.

But...

Give ten pilots the opportunity to fly a new ship and
you will get ten different pilot reports, each will have
his own opinion depending on a variety of things,
including experience, skill or ability, weight, etc.

All of these pilot reports are subjective, Wheras I
believe Dick Johnson's flight reports are more OBJECTIVE.
Backed up by flight tests with measured and recorded
results. They feature polars and numbers relating real
world results.

Over the years, manufacturers have consistantly given
their L/D numbers to be 1 or 2 points higher than was
revealed after Mr. Johnson tested a production craft.
Dick Johnson has established his credibility among
glider pilots by being very independant in his testing.

My issue is with the claimed L/D of the Sparrowhawk.

I was hoping to see an independent review of this
sailplane with polars.

Willie

Willie wrote:
My issue is with the claimed L/D of the Sparrowhawk.

I was hoping to see an independent review of this
sailplane with polars.

The tests have been done, it was discussed at the SSA convention. It
hasn't been published in Soaring, yet, so it is no surprise it isn't online.

Earlier, Marc Ramsey wrote:

The tests have been done, it was discussed
at the SSA convention. It hasn't been
published in Soaring, yet, so it is no
surprise it isn't online.

Hmmm. I was pretty sure I did see it in Soaring. Now I'd better go
check.

Willie wrote:

All of these pilot reports are subjective, Wheras I
believe Dick Johnson's flight reports are more OBJECTIVE.
Backed up by flight tests with measured and recorded
results. They feature polars and numbers relating real
world results.

Even Dick will tell you that a flight test is not exactly "real world
results". How many contests or soaring flights are flown in dead calm
conditions at steady speeds? The early ASW 24 is an interesting example
of this, as it tested well, but did not climb well in mid-afternoon
turbulence. Later models changed the airfoil slightly, showing no change
in flight testing, but definitely improving the climb. Another example
back in the '80s from Schleicher is the ASW 20, which outdid the
Ventus in dolphin style flying, but not in straight steady glides. One
glide suffered separation in pull-ups, the other did not.

Even ensuring these "dead calm" conditions is a major problem, which is
why the Alafliegs use a very carefully tested comparison sailplane to
fly with the glider they are testing, instead of trying to measure
actual sink rates.

Also, as Dick has explained in the past, his results are not based
entirely on objective criteria, but involve some "educated guessing"
about which points to ignore and exactly where to draw the curve through
points that are kept. As you might expect, not all aerodynamicists or
sailplane designers agree with this approach!

The point I'm slowly making is it sounds like you may be giving too much
weight to Dick's flight tests, instead of considering it just one of a
number of ways of evaluating a glider's performance in the _real_ world.
This is definitely more difficult to do with a new glider whose small
numbers mean there isn't much real world flying you can examine.

The people at Windward Performance tell me they believe the calculated
value of 36:1 is reasonable, based on informal glide testing against
several other types of gliders in the 35+ L/D range. I don't know if
this practical for you, but if I were seriously interested in a
SparrowHawk, I'd try to arrange to fly one, or to fly along side one in
glider with the performance I'd want it to have (Std Cirrus? Std
Libelle?). Great Western Soaring might be the place to do this, since
they are a SparrowHak dealer and will have a SparrowHawk there, and
maybe other sailplanes to rent for the comparison. A couple days there
would be money well spent when considering the purchase of a new sailplane.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

On 28 Apr 2005 20:19:15 GMT, John Galloway
wrote:

Well - there's a thing -as a non SSA UK pilot for years
until yesterday I could get straight to the Johnson
flight tests (including yesterday the newly posted
ones) and then today all of a sudden I can't.

http://www.ssa.org/Magazines/Johnson.asp

Anyone got a new link?

The wayback machine web site has som of them -
http://web.archive.org/web/200402141...es/Johnson.asp

Chris

At 10:30 02 May 2005, Chris Rowland wrote:
On 28 Apr 2005 20:19:15 GMT, John Galloway
wrote:

Well - there's a thing -as a non SSA UK pilot for years
until yesterday I could get straight to the Johnson
flight tests (including yesterday the newly posted
ones) and then today all of a sudden I can't.

http://www.ssa.org/Magazines/Johnson.asp

Anyone got a new link?

The wayback machine web site has som of them -
http://web.archive.org/web/200402141....ssa.org/Magaz
ines/Johnson.asp

Chris

Chris,

Thanks. That's a good archive site that I knew nothing
about - and it gets me back to what I could previously
access.

I still feel that it is a shame that the SSA have decided
to deny general web access to all of the Johnson tests
at the time they have posted some more recent ones.
The are a unique resource of independent data.

No polars are ever going to be totally true but Dick
Johnson has a record of picking up quite few valid
performance issues over the years. DFVLR polars are
surprisingly smooth, surprisingly better at higher
speeds than Johnson's, don't show individual flap polars,
and are available only by individual purchase 2 years
after measurement or in manufacturers manuals. I always
use Dick Johnson's data (if available) for glide computers.

John Galloway

The Idaflieg/DLR measurement data is available only after 2 years (except
when a manufacturer agrees to an earlier date) because manufacturer do
actually trust these polars - and a bad polar for a particular glider could
make the company go belly up...

The Idaflieg measurement setup is much more sophisticated than any private
individual could afford, and I would always Idaflieg data if I had a choice.

BTW, my Idaflieg polar for the ASW20 does show individual flap settings...

--
Bert Willing

ASW20 "TW"


"John Galloway" a écrit dans le message
de news: ...
At 10:30 02 May 2005, Chris Rowland wrote:
On 28 Apr 2005 20:19:15 GMT, John Galloway
wrote:
No polars are ever going to be totally true but Dick
Johnson has a record of picking up quite few valid
performance issues over the years. DFVLR polars are
surprisingly smooth, surprisingly better at higher
speeds than Johnson's, don't show individual flap polars,
and are available only by individual purchase 2 years
after measurement or in manufacturers manuals. I always
use Dick Johnson's data (if available) for glide computers.

John Galloway

I've been watching Dick Johnson's reports for several decades. The usual
pattern is for a new glider to be produced with a claimed L/D that is
significantly higher than what results from Dick's testing. The
manufacturer will sometimes pick on dick's methodology and claim that it
doesn't show everything about the glider in question or is somehow unfair.

Much later, when the glider is no longer in production, the general opinion
will be that Dick was dead on with the original report.

Dick's methodology is the best there is given limited budgets. Even so, the
results are far better than what could be reasonably expected which is a
tribute to Dick's skill as an engineer and pilot. A great benefit is that
the same methodology has been consistently and meticulously applied to a
huge number of gliders over a very long time so there is a lot of data to
compare and consequently a lot of confidence in the results.

We all owe a great debt to Dick and the TSA for the years of work they have
done testing gliders.

Bill Daniels


"John Galloway" wrote in message
...
At 10:30 02 May 2005, Chris Rowland wrote:
On 28 Apr 2005 20:19:15 GMT, John Galloway
wrote:

Well - there's a thing -as a non SSA UK pilot for years
until yesterday I could get straight to the Johnson
flight tests (including yesterday the newly posted
ones) and then today all of a sudden I can't.

http://www.ssa.org/Magazines/Johnson.asp

Anyone got a new link?

The wayback machine web site has som of them -
http://web.archive.org/web/200402141....ssa.org/Magaz
ines/Johnson.asp

Chris

Chris,

Thanks. That's a good archive site that I knew nothing
about - and it gets me back to what I could previously
access.

I still feel that it is a shame that the SSA have decided
to deny general web access to all of the Johnson tests
at the time they have posted some more recent ones.
The are a unique resource of independent data.

No polars are ever going to be totally true but Dick
Johnson has a record of picking up quite few valid
performance issues over the years. DFVLR polars are
surprisingly smooth, surprisingly better at higher
speeds than Johnson's, don't show individual flap polars,
and are available only by individual purchase 2 years
after measurement or in manufacturers manuals. I always
use Dick Johnson's data (if available) for glide computers.

John Galloway

I agree.

At 17:30 02 May 2005, Bill Daniels wrote:
I've been watching Dick Johnson's reports for several
decades. The usual
pattern is for a new glider to be produced with a claimed
L/D that is
significantly higher than what results from Dick's
testing. The
manufacturer will sometimes pick on dick's methodology
and claim that it
doesn't show everything about the glider in question
or is somehow unfair.

Much later, when the glider is no longer in production,
the general opinion
will be that Dick was dead on with the original report.

Dick's methodology is the best there is given limited
budgets. Even so, the
results are far better than what could be reasonably
expected which is a
tribute to Dick's skill as an engineer and pilot.
A great benefit is that
the same methodology has been consistently and meticulously
applied to a
huge number of gliders over a very long time so there
is a lot of data to
compare and consequently a lot of confidence in the
results.

We all owe a great debt to Dick and the TSA for the
years of work they have
done testing gliders.

Bill Daniels


'John Galloway' wrote in message
...
At 10:30 02 May 2005, Chris Rowland wrote:
On 28 Apr 2005 20:19:15 GMT, John Galloway
wrote:

Well - there's a thing -as a non SSA UK pilot for
years
until yesterday I could get straight to the Johnson
flight tests (including yesterday the newly posted
ones) and then today all of a sudden I can't.

http://www.ssa.org/Magazines/Johnson.asp

Anyone got a new link?

The wayback machine web site has som of them -
http://web.archive.org/web/200402141...w.ssa.org/Maga
z
ines/Johnson.asp

Chris

Chris,

Thanks. That's a good archive site that I knew nothing
about - and it gets me back to what I could previously
access.

I still feel that it is a shame that the SSA have
decided
to deny general web access to all of the Johnson tests
at the time they have posted some more recent ones.
The are a unique resource of independent data.

No polars are ever going to be totally true but Dick
Johnson has a record of picking up quite few valid
performance issues over the years. DFVLR polars
are
surprisingly smooth, surprisingly better at higher
speeds than Johnson's, don't show individual flap
polars,
and are available only by individual purchase 2 years
after measurement or in manufacturers manuals. I
always
use Dick Johnson's data (if available) for glide computers.

John Galloway

Is the Idaflieg/DLR measurement data available on the web somewhere?

I hear complaints about Dick's measurements but know of no other
sources of info.

at the moment I'd like to see the info for the Mosquito 303B

Chris