Butterfly

On Saturday, August 31, 2013 7:14:55 AM UTC-7, wrote:
On Wednesday, August 28, 2013 1:39:50 PM UTC-4, John Carlyle wrote:

On Tuesday, August 27, 2013 10:02:49 PM UTC-4, jfitch wrote:



I have one and I like it. But I have not used an LX7000 so I cannot compare. It has a zillion more functions and features than the CAI 302 that it replaced in my panel, and has a very nice user interface. It does a bunch of things buut its unique features seem to be:







* Nearly instantaneous wind calculation (inertially derived)







* Inertially derived Vertical Airmass Movement (VAM) which in theory eliminates horizontal gust errors







* Artificial Horizon Reference







The VAM requires some interpretation, but I think supplies some new information that I didn't have before. There are some other varios on the market claiming to use inertial sensing, but it is less clear what they actually do with it, if anything.







What do you think the VAM is telling you that you don't already know?







-John, Q3



This is a good point. I considered buying the Butterfly variometer to replace the 302 but ended up buying ClearNav. The price was not much of consideration. I watched a couple of videos of the Butterfly variometer in real flight situation and the VAM and the variometer indications hardly ever agreed. This was very confusing. Instead of feeling air pilot would spend more time with eyes in the cockpit watching not one but two indicators and get confused by conflicting information. What sense does it make to increase the workload?



The VAM is not used to filter out gusts probably because no one can figure out the algorithm to do so considering what seems often as conflicting information.



I think the LX, ClearNav and Butterfly as variometers come very close the rest seems just like options on a well equipped car.



I only wish ClearNav sound to be nicer. The sound award goes to Butterfly and LX. ClearNav are you listening? We want nicer sounding variometer.



Due to sound of ClearNav vario if I were to choose again I would have gone with LX.

There are many settings on both the vario and VAM filtering. Watching a short video will not give you much of a feel of the capability of these features, as it might in an older, simpler instrument. For example the VAM can be set up as derived from completely barographic information (like traditional netto) in which case it will track the vario needle quite well - and any additional information be effectively discarded. Set up the way I have it, the VAM and vario sometimes don't agree, and I cannot understand why. Much of the time though, when they don't agree it makes perfect sense. In straight flight it pretty much always makes sense, so like others I use the VAM rather than vario for target speed in cruise making it less likely you are chasing gusts instead of rising or sinking air.