On Wednesday, August 28, 2013 6:10:05 AM UTC-7, wrote:
Good to hear about the voice alerts. This is another very strong point in favor of the Butterfly Vario.

The C302 has a gear warning buzzer but the volume is controlled in synch with the vario volume so that when I turn the vario volume down when I am getting ready to land the gear buzzer gets turned down. When I need a quiet cockpit the most and am at risk of a gear up situation the C302 fails me. Are the volumes for each feature controlled independently in the Butterfly vario?

Yes the Butterfly seems to be manufactured by Triadis. Not sure who is doing the firmware. The voice alerts (and vario, and cruise tones) are each independently adjustable. In addition, there is a speed dependent volume adjustment (so it will be louder when going faster) and also a connection to the push-to-talk microphone switch so that when you talk on the radio, the volume will be turned down (again, a settable amount from 0-100%). I have found the latter a nice feature.

Is it a better vario than a CAI 302? I think strict vario function has been fairly well trodden ground. I like the presentation better on the Butterfly, it has nearly the same filtering adjustments, and cannot be set a lot faster than the 302 - not that you would necessarily want that, it (and the 302) get pretty twitchy when the filtering is reduced to the minimum. I expect both of these and any other pressure transducer instrument are accurately reporting the pressure rate of change, which is about all they can do.

Now, that is not the end of the story. The VAM is an inertially derived netto, and theoretically can filter horizontal gusts which a traditional netto or vario cannot. Actually in the Butterfly you are able to derive the VAM from barographic information, inertial information, or any mix of the two from 0-100%. I have settled on about 80% inertial, at 100% it seems hard to interpret, but I haven't played with all of the available filtering much yet. However I have watched the VAM and vario extensively in thermals (keeping an eye on the Flarm display of course, don't have time to look outside ), and I am beginning to wonder if I would do better thermalling from the VAM needle, instead of the vario needle. In rough western desert thermals it is kind of hard to tell without a lot of flying next to people to see if there is a difference in ultimate climb rate. There are many times when the needles agree, usually with the VAM leading the vario - this is good. There are also times when they don't agree, and often in those cases it is not obvious why.

Second, the inertially derived wind is nearly instantaneous, and varies a *great deal* around thermals. From the "feel" of things, I judge it accurate: when I feel a sudden sideways gust entering a thermal, sure enough there it is displayed on the vario. Vector shifts of 180 deg and 20 knots velocity compared to wind average on the PDA are somewhat common where I fly. I have just been informed by Buttefly that I can display this difference on iGlide, haven't tried it yet as I just got the equipment needed to connect it up. I am beginning to learn to use this information to tell me which direction the thermal core is.

So there is extra information available to the instrument, and the pilot, that was not there on the CAI 302. I don't think it will instantly turn me into a threat at the Nationals. However I hopeful it will improve my climbs, when and if I learn how to use it. In the mean time it is a damned entertaining instrument!