Re: 302 Engine Noise Level ?

[Robert & Susan Mercer]

Yup. I have the 2.63 firmware now, but no ENL sensor, and don't have a motor
glider but still get a ENL landout in SeeYou shortly after release. I had
to upgrade firmware as a last resort to download a flight that got stuck
inside the instrument during a contest.

Dave Mercer

"Bob Kibby" > wrote in message
. net...
> I have the engine noise level (ENL) upgraded Cambridge 302. I also have a
> motor glider. When I analyze my flights with SeeYou I get a "landed out"
> indication due to ENL when I haven't started my engine. When I compare my
> 302 ENL output with my Cambridge Model 20 ENL output I see a gross
> difference, i.e. the 302 output is an order of magnitude higher. Is anyone
> else with the ENL upgrade to the 302 experiencing this problem? Thanks,
> "2BK"
> --
>
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[Ian Strachan]

In article >, Bob Kibby
> writes

>I have the engine noise level (ENL) upgraded Cambridge 302. I also have a
>motor glider. When I analyze my flights with SeeYou I get a "landed out"
>indication due to ENL when I haven't started my engine. When I compare my
>302 ENL output with my Cambridge Model 20 ENL output I see a gross
>difference, i.e. the 302 output is an order of magnitude higher.

The original Cambridge ENL system as fitted to the models 10, 20 and 25,
was based on a maximum ENL figure of 195. So a two-stroke motor glider
should give fixes with ENL values of about this figure when the engine
is run at high power.

The more modern Model 302 conforms with the IGC Specification which
requires that the ENL system uses the full three-number range from 000
to 999. So for that reason alone you will get some five times the ENL
figures that you were used to with the earlier models (which have
"grandfather rights" and were not changed from their original maximum
ENL of 195 to 999).

For any IGC approved recorder with an ENL system, the ENL numbers that
you should get in various phases of flight, are given in Annex B to the
IGC approval document. These are based on tests made by the IGC GNSS
Flight Recorder Approval Committee (GFAC), that I chair. All current
IGC approval documents are posted on the web at:

http://www.fai.org/gliding/gnss/igc_approved_frs.pdf

and for the recorders to which you refer:
http://www.fai.org/gliding/gnss/cambridge10_20_25.pdf
and
http://www.fai.org/gliding/gnss/cambridge302.pdf

For ENL figures, see para B4 in these documents.

--------------------------

General

If any recorder is producing very different ENL values to those given in
Annex B to the approval, as a general rule it should be returned to the
manufacturer for the ENL system to be re-set to the Annex B values (or
to an agent of the manufacturer who is authorised to make such
adjustments and to carry out a secure re-set on the recorder).

GFAC has occasionally seen IGC files from recorders where the ENL values
seem to have been set too low (not sensitive enough) and also too high
(too sensitive). Fortunately, this is unusual. We remind manufacturers
from time to time that when a recorder is sold it should conform to what
it says in the IGC approval document. Pilots should check also, which
is what you are doing!

Some gliders produce an "organ pipe" sound if flown with the cockpit
panels open and with either sideslip or at high speed. Since this can
produce high ENL figures on the IGC file (but still lower than with
engine) these conditions should be avoided. Again, see Annex B to the
IGC approval document for the type of recorder that you use.

Finally, if you still think that you have an anomaly in the IGC file
from a particular recorder, you can always email the IGC file(s) to me
and GFAC will have a look at it and advise you.

--
Ian Strachan
Chairman, IGC GNSS Flight Recorder Approval Committee

Bentworth Hall West
Bentworth
Alton, Hampshire GU34 5LA
ENGLAND


Tel: +44 1420 564 195
Fax: +44 1420 563 140