logansc
Well Known Member
I?m having trouble working this one out.
My Rocket has been flying fine for years, but I have just installed an AFS/Dynon ADHR supporting a single AF5600 display and the other equipment necessary in order to gain ADSB compliance. I decided to retain my standard ASI and altimeter as much for aesthetic reasons as any other. The old ASI is now plumbed to a new AoA capable Dynon pitot that is ?tee?d? to the ADHR?s in the rear of the airplane. Because this is my 4th system upgrade (!) it has worked out that the two systems are connected to two separate static ports---the standard airspeed to a forward set and the ADHR?s to a separate set of sources on the rear fuselage. Both airspeed indicators work but display speeds that in addition to being very low, are different from each other. I have some confidence at least in the accuracy of the static sources since both the standard altimeter and the AF5600 altimeter tape are in agreement and are connected to the same two separate static sources as the ASI?s.
The displayed speed differences vary with airspeed but at modest cruise power settings where I used to see 165+ knots or so, I?m now seeing 125 up front (standard ASI) and 115 or so on the AFS tape driven by the ADHR. At approach speeds of (an estimated) 80 knots, the ASI is reading closer to 50 knots and the AF5600 airspeed tape is even lower. Turning final at ?50 knots? is interesting!
An NTPS ground speed flight test and both GPS ground speeds (GNS530W and AFS5600) agree with each other at around 170 knots for the first configuration above (where the ASI is showing only 125 knots or so). The speed sourced from the ADHR can be ?tuned? to the correct number if need be, but the standard ASI still should not be that far off. The discrepancy between the two airspeeds can probably be explained at least in part by the two different static sources but that doesn?t explain why either or both of them are so low. Seems to me that all this means I must have a pitot (rather than/or in addition to, a static) leak somewhere OR, connecting two airspeeds to a single pitot tube is not workable in this particular configuration. Or, maybe it's something else entirely?
Before I take the whole thing apart again (which in the Rocket is a significant undertaking), does anything here stand out as a probable cause or course of action to anyone?
Sorry for the long post, building the airplane in the first place was way easier than this!
Lee...
My Rocket has been flying fine for years, but I have just installed an AFS/Dynon ADHR supporting a single AF5600 display and the other equipment necessary in order to gain ADSB compliance. I decided to retain my standard ASI and altimeter as much for aesthetic reasons as any other. The old ASI is now plumbed to a new AoA capable Dynon pitot that is ?tee?d? to the ADHR?s in the rear of the airplane. Because this is my 4th system upgrade (!) it has worked out that the two systems are connected to two separate static ports---the standard airspeed to a forward set and the ADHR?s to a separate set of sources on the rear fuselage. Both airspeed indicators work but display speeds that in addition to being very low, are different from each other. I have some confidence at least in the accuracy of the static sources since both the standard altimeter and the AF5600 altimeter tape are in agreement and are connected to the same two separate static sources as the ASI?s.
The displayed speed differences vary with airspeed but at modest cruise power settings where I used to see 165+ knots or so, I?m now seeing 125 up front (standard ASI) and 115 or so on the AFS tape driven by the ADHR. At approach speeds of (an estimated) 80 knots, the ASI is reading closer to 50 knots and the AF5600 airspeed tape is even lower. Turning final at ?50 knots? is interesting!
An NTPS ground speed flight test and both GPS ground speeds (GNS530W and AFS5600) agree with each other at around 170 knots for the first configuration above (where the ASI is showing only 125 knots or so). The speed sourced from the ADHR can be ?tuned? to the correct number if need be, but the standard ASI still should not be that far off. The discrepancy between the two airspeeds can probably be explained at least in part by the two different static sources but that doesn?t explain why either or both of them are so low. Seems to me that all this means I must have a pitot (rather than/or in addition to, a static) leak somewhere OR, connecting two airspeeds to a single pitot tube is not workable in this particular configuration. Or, maybe it's something else entirely?
Before I take the whole thing apart again (which in the Rocket is a significant undertaking), does anything here stand out as a probable cause or course of action to anyone?
Sorry for the long post, building the airplane in the first place was way easier than this!
Lee...