AirTalk.org

Gary Emerson · Guest

Greetings,

Looking for some real world data on what the max altitude that a Duo T
can sustain level flight. Would also be nice to know what sort of climb
performance people have seen at lower altitudes. I know it'll climb to
6500ft MSL and average around 150 FPM, but hoping to get more data points.

Gary

BTIZ · Guest

Now that is an interesting data point... I'd be interested in others also..

If that DuoT can't climb above 6500ft MSL at better than 150fpm, then I
would not even attempt a takeoff out here in the summer time. Airport Elev,
2833MSL, Baro 30.00, Temp 100F, puts the DA at 6000ft. Granted there can be
found a thermal right on the runway to assist, but there is also strong down
near strong up.

Another favorite launch site, at 5500MSL, Baro 30.00 and 90F puts the DA at
8500, even if the temp is still only 80F, the DA is 7940.

I've noticed a DG500M on the market that flies regularly out of Colorado,
would the seller care to offer some data points?

Maybe the DG808B?

BT
"Gary Emerson" <emerson_gary (AT) hotmail (DOT) com> wrote

BTIZ · Guest

ok... I have received two lashes with the noodle that the Duo T is a
"sustainer" and not self launch...

but by the same token... of the Duo T can only "sustain" 6500MSL DA... it is
nothing more than a glider out here... I'll admit... I did use that word
"take off" in regards to "sustainer" operations

The POINT is that Density Altitude during standard summer operations will
make the use of the "sustainer engine" worthless. 6500DA is below GROUND
LEVEL in our peak flying season, maybe it will only extend the glide back to
something landable.. but I would not want to count on it to "maintain
altitude".

But then again.. with temps such as these.. we don't need no stinking
engine.

BT

"BTIZ" <btiznospm2 (AT) cox (DOT) nospm.net> wrote

Gary Emerson · Guest

Just to clarify just a tad, we shut down the turbo at 6500 ft because we
had final glide back to home, not because we weren't climbing. We still
had about 125-150 FPM up at that point. I've never had a need to fire
it up at any higher altitude and so I'm curious if anyone else has...
I'd love to hear that you could hold altitude at 10k ft.

BTIZ wrote:

Bill Daniels · Guest

Here's an exercise. Look at the Duo's L/D curve for the value at a useful
speed like 100kts then divide that into the flying weight. That will be the
thrust required to maintain level flight at that speed.

Maybe replacing that balky IC engine & prop with one or two of Bob Carlsons
dinky microjets that burn the Jet-A ballast might work.

Here's how it worked out with the Nimbus 2C. L/D at 100 Kts at 1433 lbs. GW
is 37:1. 1433/37 = 39Lbs thrust. One AMT microjet produces 54 pounds of
thrust at 100 Kats - probably up to the flight levels. That's good cruise
plus a little extra. It gets even better as the fuel weight burns off.

Bill Daniels

"BTIZ" <btiznospm2 (AT) cox (DOT) nospm.net> wrote

John Galloway · Guest

Look at the climb rate/altitude in the graph and time
to climb graph in the Duo T manual? These graphs are
realistic - for example I know that the Discus 2cT
graphs were derived from 11 hours of engine climb testing
time. The Duo T will only be expected to get as much
as 150fpm at low density altitudes.

BTW the advantageous climb rate of a self sustainer
isn't just the rate of climb above level flight but
the rate of climb above the rate of sink at around
max LD - so the Duo T at typical UK flying altitudes
is gaining almost 300fpm over its non turbo twin =
notionally 3000 feet higher after 10 minutes engine
burn and, crucially, about 10 miles closer to an airfield/ridge/th
ermal.

Even with zero rate of climb in the US midwest then
if the Duo T engine is started at a safe altitude then
the likelyhood of an off-airfield landing will be considerably
reduced - it just might not be the home airfield:-)

At 03:06 26 November 2005, Gary Emerson wrote:

Greg Arnold · Guest

John Galloway wrote:

John Galloway · Guest

At 16:18 26 November 2005, Greg Arnold wrote:

Walter Kronester · Guest

To supply some real world data:
At density altitudes from around 3500 ft to 7000 ft I got
between 250 and 300 fpm with 170 lbs pilot weight
and 180 - 230 fpm with (2 persons) 380 lbs (no additional water).
(VSI-Output, no precise measurement, but in correlation with altimeter
data).
Theese values were very similar in two different airplanes.
I think this climb rate is really acceptable for a sustainer only engine,
but please do never expect to escape from a downwash with a sustainer
engine.
A glide ratio of 16 seems realistic for me with the engine extended but not
running.
So before extending the engine look out for an emergency field near by.
I hope this helps
Walter Kronester

PS: I love this bird!

BTIZ · Guest

Thanx Walter.. I take it you are referring to the DuoT

"Walter Kronester" <wkronester.no_spam. (AT) web (DOT) de> wrote

Ted · Guest

I fly a Ventus CM which uses the same basic SOLO engine block. The
major problem I have with higher flights is the progressive over rich
mixture at altitude ( there is no mechanism for leaning.) I have
climbed to 12,000 but started with marginally lean carburator jet
settings. I think John Lubon (who also flys a CM) told me he was able
to get to the 14,000 ft. published service ceiling by setting the
mixture so lean on the ground that the engine would only run with
partial choke! One technique I don't recommend is to try to lean by
partially closing the fuel shut of valve. I managed to burn a cylinder
trying this trick.
BTIZ wrote:

graham@sgi.com · Guest

At Boulder we had a DG808B & my DG500M this past Summer. The DG808B
seems to outperform the Pawnee by most everyone's estimation probably
regularly beating 500fpm on the 8500 DA typicall day as quoted below,
thats without water but still very impressive to watch and very quiet.

My DG500M doesn't do as well as the 808 but has less power and much
more weight. Looking through my notes where I actually recorded data I
see on July 10 at Boulder (1V5) approx 5300MSL, 88F, Baro 30.01, 9
minutes to shutdown at 8300 ft. Probably a minute of that was with the
engine idling before shutdown. So about 375fpm actual but I was solo.
A few weeks before that flying dual with my buddy Rolf at Gallup NM
dual climb rates at DA of about 10k looked to be about 300fpm. From
the logger traces no averages below 250fpm nor any above 400fpm dual
over a week with typicall DA 10k.

Without checking all the data (aren't loggers cool ?) it feels like the
DG500M gets better climb performance on its own then when behind the
180HP Super Cup but not as good as the 235HP Pawnee. It also feels
that weight makes more of a difference then DA. I have never self
launched my DG below Boulder's field elev nor fly in cooler weather so
can't really comment on the other side of the spectrum. Though I read
(maybe on the Aux Sailplane Assc news group or the DG owner site) that
the flapped ships do much better. It is interesting that DG had
problems certifying the new non-flapped DG-1000 as a self launcher and
for now its only available as a "turbo" like the Duo Discus. I follow
the manual and climb at flaps +10degrees at Vy 49kts.

Graham Beasley DG-500M Hotel Golf
home.comcast.net/~grahambeasley/dg4sale

BTIZ wrote:

John Galloway · Guest

At 00:54 27 November 2005, Walter Kronester wrote:

Bob Korves · Guest

[email]graham (AT) sgi (DOT) com[/email] wrote in
news:1133114507.285099.78730 (AT) f14g2000cwb (DOT) googlegroups.com:

Paul · Guest

Though I read