Cambridge 302 problem..HELP Please

[Robert Holliday]

My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates 10
knots lift (it is set up for super netto). The total energy is set at 0% as
per instructions. It is not set up for electronic compensation. I checked
for leaks in the TE probe and tubing and found none. I just had it
upgraded to the USB port and the software fixed so it would not "fill
up" the flight log storage. Has anyone had this kind of problem? any
ideas?
thanks.
bob holliday

[T8]

On Jun 22, 11:00*am, Robert Holliday > wrote:
> My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates 10
> knots lift (it is set up for super netto). The total energy is set at 0% as
> per instructions. It is not set up for electronic compensation. I checked
> for leaks in the TE probe and tubing and found none. I just had it
> upgraded to the USB port and the software fixed so it would not "fill
> up" the flight log storage. Has anyone had this kind of problem? any
> ideas?
> thanks.
> bob holliday

Your 302 requires pitot, static and TE connections. Did you
mistakenly connect the static port to a TE source, thereby causing the
TAS computed by the 302 to be very high?

-T8

[Darryl Ramm]

On Jun 22, 8:14*am, T8 > wrote:
> On Jun 22, 11:00*am, Robert Holliday > wrote:
>
> > My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates 10
> > knots lift (it is set up for super netto). The total energy is set at 0% as
> > per instructions. It is not set up for electronic compensation. I checked
> > for leaks in the TE probe and tubing and found none. I just had it
> > upgraded to the USB port and the software fixed so it would not "fill
> > up" the flight log storage. Has anyone had this kind of problem? any
> > ideas?
> > thanks.
> > bob holliday
>
> Your 302 requires pitot, static and TE connections. *Did you
> mistakenly connect the static port to a TE source, thereby causing the
> TAS computed by the 302 to be very high?
>
> -T8

That would be my guess as well.

And when debugging C302 things like this go to Screen #10 and see what
it thinks the TAS is.

Darryl

[Paul Remde]

Hi Bob,

My best guess is that the polar data is not entered into the 302 correctly.
Please double check it and perhaps have a soaring friends double check it as
well.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.

"Robert Holliday" > wrote in message
...
> My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates
> 10
> knots lift (it is set up for super netto). The total energy is set at 0%
> as
> per instructions. It is not set up for electronic compensation. I checked
> for leaks in the TE probe and tubing and found none. I just had it
> upgraded to the USB port and the software fixed so it would not "fill
> up" the flight log storage. Has anyone had this kind of problem? any
> ideas?
> thanks.
> bob holliday
>

[Richard[_9_]]

On Jun 22, 8:00*am, Robert Holliday > wrote:
> My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates 10
> knots lift (it is set up for super netto). The total energy is set at 0% as
> per instructions. It is not set up for electronic compensation. I checked
> for leaks in the TE probe and tubing and found none. I just had it
> upgraded to the USB port and the software fixed so it would not "fill
> up" the flight log storage. Has anyone had this kind of problem? any
> ideas?
> thanks.
> bob holliday

Robert,

Check you neumatic connections, pitot, static & TE to the 302 before
you fly.

During Flight

Go to screen 10 and make sure the 302 indicated airspeed is close to
your airspeed indicator. This will alert you if the pneumatic
corrections are correct.


Richard
www.craggyaero.com

[Robert Holliday]

That is the first thing i checked. the TE tube is patent and if you blow
into the TE probe the air comes out the tube that i have connected to the
TE port on the instrument.
bob
At 15:14 22 June 2009, T8 wrote:
>On Jun 22, 11:00=A0am, Robert Holliday wrote:
>> My 302 seems to work OK at 60 knots but when i fly 80 knots it
indicates
>=
>10
>> knots lift (it is set up for super netto). The total energy is set at
0%
>=
>as
>> per instructions. It is not set up for electronic compensation. I
>checked
>> for leaks in the TE probe and tubing and found none. I just had it
>> upgraded to the USB port and the software fixed so it would not "fill
>> up" the flight log storage. Has anyone had this kind of problem? any
>> ideas?
>> thanks.
>> bob holliday
>
>Your 302 requires pitot, static and TE connections. Did you
>mistakenly connect the static port to a TE source, thereby causing the
>TAS computed by the 302 to be very high?
>
>-T8
>

[David Prather]

I have the same problem-- tremendous "lift" starting at 80 kts. I am
trying to share the TE connection with a mechanical Winter vario that
works with a capacity flask. Does anyone else share TE between a
mechanical vario and the 302?

-David Prather


At 15:00 22 June 2009, Robert Holliday wrote:
>My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates
10
>knots lift (it is set up for super netto). The total energy is set at 0%
>as
>per instructions. It is not set up for electronic compensation. I
checked
>for leaks in the TE probe and tubing and found none. I just had it
>upgraded to the USB port and the software fixed so it would not "fill
>up" the flight log storage. Has anyone had this kind of problem? any
>ideas?
>thanks.
>bob holliday
>
>

[David Prather]

I have the same problem-- tremendous "lift" starting at 80 kts. I am
trying to share the TE connection with a mechanical Winter vario that
works with a capacity flask. Does anyone else share TE between a
mechanical vario and the 302?

-David Prather


At 15:00 22 June 2009, Robert Holliday wrote:
>My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates
10
>knots lift (it is set up for super netto). The total energy is set at 0%
>as
>per instructions. It is not set up for electronic compensation. I
checked
>for leaks in the TE probe and tubing and found none. I just had it
>upgraded to the USB port and the software fixed so it would not "fill
>up" the flight log storage. Has anyone had this kind of problem? any
>ideas?
>thanks.
>bob holliday
>
>

[Darryl Ramm]

On Jun 24, 7:45*pm, David Prather
> wrote:
> I have the same problem-- tremendous "lift" starting at 80 kts. I am
> trying to share the TE connection with a mechanical Winter vario that
> works with a capacity flask. Does anyone else share TE between a
> mechanical vario and the 302?
>
> -David Prather
>
> At 15:00 22 June 2009, Robert Holliday wrote:
>
> >My 302 seems to work OK at 60 knots but when i fly 80 knots it indicates
> 10
> >knots lift (it is set up for super netto). The total energy is set at 0%
> >as
> >per instructions. It is not set up for electronic compensation. I
> checked
> >for leaks in the TE probe and tubing and found none. I just had it
> >upgraded to the USB port and the software fixed so it would not "fill
> >up" the flight log storage. Has anyone had this kind of problem? any
> >ideas?
> >thanks.
> >bob holliday
>
>

Share the TE line? Hopefully not joined close by. One of the leading
claims to fame of the C302 is it is a direct reading variometer. It
digitally measures pressure and calculates the rate of change, it is
not measuring air flow to/from the capacity like with a vane based
vario. If you have both on that TE line split the line well away from
the instruments so there is some impedance in the line so the flow to
the flask does not screw up the C302 entirely. The standard
recommendation is to split back behind the seat area and run two lines
up to the panel.

You can also just put the C302 on the static port (esp. if you have a
tripe probe) and use electronic compensation. I know Dave Ellis
claimed a good TE probe should be better, but the electronic
compensation works great for me. That also provides you some
redundancy between a problem in the TE line talking out both varios.

Darryl

[T8]

On Jun 24, 10:45*pm, David Prather
> wrote:
> I have the same problem-- tremendous "lift" starting at 80 kts. I am
> trying to share the TE connection with a mechanical Winter vario that
> works with a capacity flask. Does anyone else share TE between a
> mechanical vario and the 302?
>
> -David Prather

David -

302 works best with dedicated TE and static ports. Excess volumes in
the systems (capacity vario, asi, altimiter) play hell with pressure
transducer instruments like 302. TE can be shared, with some loss of
performance. As previously noted, the closer the "tee" is to the
probe, the better. I would suggest test flying with dedicated ports,
then work from there to a compromise that works for you. Pitot may be
shared with asi.

As far as anomalous "lift" indications in cruise, obvious things to
check were covered -- correct connections, no leaks (including probe
socket o-rings), correct polar in 302, correct ias showing on 302.

Electronic compensation is fraught with difficulties (chiefly that is
extremely sensitive to *small* pneumatic errors in both magnitude and
timing) and never recommended as a preferred approach.

-Evan Ludeman / T8

[T8]

On Jun 25, 8:50*am, T8 > wrote:
> On Jun 24, 10:45*pm, David Prather
>
> > wrote:
> > I have the same problem-- tremendous "lift" starting at 80 kts. I am
> > trying to share the TE connection with a mechanical Winter vario that
> > works with a capacity flask. Does anyone else share TE between a
> > mechanical vario and the 302?
>
> > -David Prather
>
> David -
>
> 302 works best with dedicated TE and static ports. *Excess volumes in
> the systems (capacity vario, asi, altimiter) play hell with pressure
> transducer instruments like 302. *TE can be shared, with some loss of
> performance. *As previously noted, the closer the "tee" is to the
> probe, the better. *I would suggest test flying with dedicated ports,
> then work from there to a compromise that works for you. *Pitot may be
> shared with asi.
>
> As far as anomalous "lift" indications in cruise, obvious things to
> check were covered -- correct connections, no leaks (including probe
> socket o-rings), correct polar in 302, correct ias showing on 302.
>
> Electronic compensation is fraught with difficulties (chiefly that is
> extremely sensitive to *small* pneumatic errors in both magnitude and
> timing) and never recommended as a preferred approach.
>
> -Evan Ludeman / T8

Edit: "TE can be shared with a capacity type vario, with some loss of
performance". But don't put the tee close to the instruments if you
do this!

All ports may be shared with other pressure transducer type
instruments, without loss of performance. Tee location not critical
in this case.

-T8

[Robert Holliday]

Thanks to all for the help.
The polar was set incorrectly.
I really appreciate everything.
bob holliday
At 03:18 25 June 2009, Darryl Ramm wrote:
>On Jun 24, 7:45=A0pm, David Prather
> wrote:
>> I have the same problem-- tremendous "lift" starting at 80 kts. I am
>> trying to share the TE connection with a mechanical Winter vario that
>> works with a capacity flask. Does anyone else share TE between a
>> mechanical vario and the 302?
>>
>> -David Prather
>>
>> At 15:00 22 June 2009, Robert Holliday wrote:
>>
>> >My 302 seems to work OK at 60 knots but when i fly 80 knots it
>indicates
>> 10
>> >knots lift (it is set up for super netto). The total energy is set at
>0%
>> >as
>> >per instructions. It is not set up for electronic compensation. I
>> checked
>> >for leaks in the TE probe and tubing and found none. I just had it
>> >upgraded to the USB port and the software fixed so it would not
"fill
>> >up" the flight log storage. Has anyone had this kind of problem? any
>> >ideas?
>> >thanks.
>> >bob holliday
>>
>>
>
>Share the TE line? Hopefully not joined close by. One of the leading
>claims to fame of the C302 is it is a direct reading variometer. It
>digitally measures pressure and calculates the rate of change, it is
>not measuring air flow to/from the capacity like with a vane based
>vario. If you have both on that TE line split the line well away from
>the instruments so there is some impedance in the line so the flow to
>the flask does not screw up the C302 entirely. The standard
>recommendation is to split back behind the seat area and run two lines
>up to the panel.
>
>You can also just put the C302 on the static port (esp. if you have a
>tripe probe) and use electronic compensation. I know Dave Ellis
>claimed a good TE probe should be better, but the electronic
>compensation works great for me. That also provides you some
>redundancy between a problem in the TE line talking out both varios.
>
>Darryl
>