Van's Air Force
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GRT Mini X airspeed sluggish?
- Thread starter markscogg
- Start date
erikpmort
Well Known Member
I think I second this problem. But not for landing. However it hasn't hurt me. Better than reading fast I guess. I've made better landings since I moved to an efis over the old steam gauge. I can hold a tighter airspeed and anticipate trends on the tape. I really love the value of the mini. I want an hxr bad now.
Greg_Toman
Member
Airspeed Response and Rate-of-Change
There is no adjustment on the Mini for the filtering of the airspeed. This filtering could be responsible for the difference in response time of the airspeed you have observed. If there were significant restrictions or possibly water trapped in your pitot/static connections, this could also cause an effect like this.
The filtering we use on the airspeed is the same we have used for the last 10 years on all of our EFIS products. The filtering was chosen as a compromise between response time and smoothness. We have never had any complaints or issues regarding response time of our airspeed, so if it is significantly slow, I would take a look to make sure the pitot line is not kinked or somehow restricted.
The smoothness of our airspeed allows the rotating digits to clearly show the rate-of-change of airspeed, which I find as important as the airspeed itself.
The observation about the landings being better with an EFIS are probably true. I bought an airplane with a competitors EFIS, and I found the airspeed responded quickly, but was so noisy that the rotating digits did not convey any rate-of-change of airspeed, as they were just moving erratically. I had not realized how my brain was picking that data up unconsciously from our EFIS, and how without rate-of-change of airspeed it was harder to know how my airspeed was changing. I had to compensate by re-checking my airspeed more often on approach, and I did find it harder to control my airspeed as precisely.
Greg Toman
Grand Rapids Technologies, Inc.
There is no adjustment on the Mini for the filtering of the airspeed. This filtering could be responsible for the difference in response time of the airspeed you have observed. If there were significant restrictions or possibly water trapped in your pitot/static connections, this could also cause an effect like this.
The filtering we use on the airspeed is the same we have used for the last 10 years on all of our EFIS products. The filtering was chosen as a compromise between response time and smoothness. We have never had any complaints or issues regarding response time of our airspeed, so if it is significantly slow, I would take a look to make sure the pitot line is not kinked or somehow restricted.
The smoothness of our airspeed allows the rotating digits to clearly show the rate-of-change of airspeed, which I find as important as the airspeed itself.
The observation about the landings being better with an EFIS are probably true. I bought an airplane with a competitors EFIS, and I found the airspeed responded quickly, but was so noisy that the rotating digits did not convey any rate-of-change of airspeed, as they were just moving erratically. I had not realized how my brain was picking that data up unconsciously from our EFIS, and how without rate-of-change of airspeed it was harder to know how my airspeed was changing. I had to compensate by re-checking my airspeed more often on approach, and I did find it harder to control my airspeed as precisely.
Greg Toman
Grand Rapids Technologies, Inc.
GRT air data presentation
I second Greg's comments on how our brain "uses" the data.
I tested the first EFIS extensively in flight and brought along various human factors experts from different regions in the FAA.
We learned a lot in the early days. One interesting thing was "cheating".
The data showed pilots used analog data from their peripheral vision (coming from backup steam gauges) and were not aware of it. Particularly VSI.
Anyway, long story short. I use the GRT mini as my primary airspeed indicator currently in a 9A. The filtering and rate of change are spot on for control of the aircraft in all realms of flight. Give it some time and I think you will see the light. Report back, if you would and let us know.
I second Greg's comments on how our brain "uses" the data.
I tested the first EFIS extensively in flight and brought along various human factors experts from different regions in the FAA.
We learned a lot in the early days. One interesting thing was "cheating".
The data showed pilots used analog data from their peripheral vision (coming from backup steam gauges) and were not aware of it. Particularly VSI.
Anyway, long story short. I use the GRT mini as my primary airspeed indicator currently in a 9A. The filtering and rate of change are spot on for control of the aircraft in all realms of flight. Give it some time and I think you will see the light. Report back, if you would and let us know.
GRT Mini X Pitot Static tube size
The Mini X and the Skyview in this plane are both hooked up with Nylo-Seal -4 fittings.
That is 1/4" OD tube with .035 wall . Then there is an insert placed in each tube end before locking it down in the union "T", elbow or whatever you are using. (insert part number is 259-N 04.)
The hole in this insert is small, just slightly over 1/8".
Is that what most people are using?
Can you get a seal without using the fitting in the end of the tube?
The Mini X and the Skyview in this plane are both hooked up with Nylo-Seal -4 fittings.
That is 1/4" OD tube with .035 wall . Then there is an insert placed in each tube end before locking it down in the union "T", elbow or whatever you are using. (insert part number is 259-N 04.)
The hole in this insert is small, just slightly over 1/8".
Is that what most people are using?
Can you get a seal without using the fitting in the end of the tube?
