Butterfly vario side-by-side with ClearNav vario

On Friday, May 17, 2013 2:59:18 PM UTC-6, son_of_flubber wrote:
On Friday, May 17, 2013 2:23:21 PM UTC-4, Mike the Strike wrote:

The advent of varios with inertial probes that enable the compensation or identification of horizontal gusts



So does the ClearNav

1)have an inertial probe and

2)does it have the software (at the moment) to filter out horizontal gusts?



So does an "inertial probe" and an "accelerometer" both provide the same sensor inputs to the software?

I'm not sure how it is actually being implemented but I would interpret "inertial probe" as an IMU (Inertial Measurement Unit). IMU's have 3-axis gyros and 3-axis accelerometers. The gyros keep the accelerometers aligned up-down, east-west and north-south. MEMS IMU's these days are nearly chip-size so one could be inside the vario with GPS position data serving as a calibration signal to compensate for drift. This means vertical acceleration can be measured and the integral (velocity) can be displayed as a vario signal. The advantages of an inertial vario include zero lag, gust insensitivity and complete freedom from TE probes and associated plumbing.

The gust/thermal discrimination is done by comparing the inertial-TE with air-data TE. If the air-data shows a gain in total energy but the inertial data doesn't, it's a gust.

The above is the most elegant implementation but partial implementation could also provide an advance over the old air-data only varios.

In theory, both the butterfly and the CN have enough innards to really advance variometry, because they have the potential to measure the vertical speed of air around the glider.

If you fly in to a thermal, the g meter increases. If you pull back on the stick the g meter increases. But the gyros can tell that the glider nosed up in the latter case. So, the vario can measure "netto g" if you will, the acceleration of the glider caused by changes in the surrounding air.

This is much faster than a vario. For a vario to work, you have to fly into the rising air, g increases, F = MA does its work, the glider starts rising vertically, then the vario can start to measure it. The system based on g and heading does it instantly, at least giving a second or two earlier lift detection.

Looking at sideways g, correcting for yaw, also can tell the vario if there is a sideways gust. Looking at fore and aft g can tell the vario if the glider has entered a wind shear on the nose rather than vertical thermal.

Eventually, by comparing the GPS track through space with the relative wind, these various could also measure outside air motion directly.

I don't know how much of this is currently programmed in to either one, but the potential seems intriguing.

John Cochrane

On Friday, May 17, 2013 6:20:24 PM UTC-7, wrote:
If you fly in to a thermal, the g meter increases. If you pull back on the stick the g meter increases. But the gyros can tell that the glider nosed up in the latter case. So, the vario can measure "netto g" if you will, the acceleration of the glider caused by changes in the surrounding air.


What happens when the flaps go positive?

Marc

I am also very interested in the Butterfly vario. I have some questions that the Butterfly people have not answered for me yet.

I fly with a mechanical vario on the T.E. probe and my 302 with electronic compensation. I wanted two independent systems and I was having difficulties with the 302 and mechanical varios on the same T.E. probe line.

How would the Butterfly work with electronic compensation? Any significant loss of functions?

What issues could be anticipated with the Butterfly vario and a mechanical vario (Winter or Sage) sharing the same T.E. probe?

Guy Acheson "DDS"

On Sun, 19 May 2013 11:19:48 -0700, drguyacheson wrote:

I am also very interested in the Butterfly vario. I have some questions
that the Butterfly people have not answered for me yet.

I fly with a mechanical vario on the T.E. probe and my 302 with
electronic compensation. I wanted two independent systems and I was
having difficulties with the 302 and mechanical varios on the same T.E.
probe line.

Feeding both a capacity-based vario and a pressure sensing vario from the
same TE probe is known to cause problems if the T-junction is close to
both instruments. Moving the T-junction away from the panel, i.e. using
long connections between the T and the two varios fixes it. There's a
note on Mike Borgelt's website saying that if the T-junction is either
under your seat pan or behind it the problem should disappear.

What issues could be anticipated with the Butterfly vario and a
mechanical vario (Winter or Sage) sharing the same T.E. probe?

As described above.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Sunday, 19 May 2013 21:19:48 UTC+3, wrote:
I am also very interested in the Butterfly vario. I have some questions that the Butterfly people have not answered for me yet.



I fly with a mechanical vario on the T.E. probe and my 302 with electronic compensation. I wanted two independent systems and I was having difficulties with the 302 and mechanical varios on the same T.E. probe line.



How would the Butterfly work with electronic compensation? Any significant loss of functions?



What issues could be anticipated with the Butterfly vario and a mechanical vario (Winter or Sage) sharing the same T.E. probe?



Guy Acheson "DDS"

I have BF and mechanical vario (0,3l capacity) connected to same TE tube. I haven't witness any problems so far. BF vario requires TE tube, there is no option for electronic compensation.

krasw

BF vario requires TE tube, there is no option for electronic compensation.

Thats right. Discussions about this are old and I guess you all know the arguments. As you may figure we believe that TE compensation is way superior.

Cheers
Marc

On Wednesday, May 15, 2013 3:50:37 PM UTC-7, wrote:
Anyone used these two varios in the same flight? How do they compare?

The Butterfly has flap input, analog potentiometer so continuous reading. I don't know if they use it for anything, but the input is there.

On Sunday, May 19, 2013 11:24:46 PM UTC+2, jfitch wrote:
On Wednesday, May 15, 2013 3:50:37 PM UTC-7, wrote:

Anyone used these two varios in the same flight? How do they compare?



The Butterfly has flap input, analog potentiometer so continuous reading. I don't know if they use it for anything, but the input is there.

yep, we do. We will use it in the future for flap position indication and flap optimization + to help filter flap-induced (dynamic) changes in lift better.