I’d keep a totally independent attitude source any time. I already had some issues with my Aspen, luckily all in VMC, and it told me some lessons. It’s relieving to know how to double check whether instruments are indicating well.
Looking at the electric motor I drive my vacuum pump / KI256 test rig, I’d say about 1/4HP at 1200rpm and 1/2HP at 2400rpm, very roughly.
Friction losses in the engine will be 2 orders of magnitude bigger – extrapolate the curves here backwards to zero power.
How much power does it take to run a vacuum pump? 1/4 HP?
good, thought it was only on the exp version.
Gonna upgrade my exp setup to software V8.0 today, hope for only pleasant surprises 
Dan wrote:
Apologies, my wording in this post wasn’t really what I thought… and so was the reference to Density Altitude, which I am presented with whilst on the ground… but which is, as far as I know, only available for the Experimental G5 model.
You get this in certified G5s as well. At least I’ve seen it in a C172 with dual G5’s.
@Airborne_Again, sure one needs TAS, e.g. OAT via GAD13 analog/digital converter for winds aloft. On top of the GMU11 magnetometer thru the CAN bus.
Apologies, my wording in this post wasn’t really what I thought… and so was the reference to Density Altitude, which I am presented with whilst on the ground… but which is, as far as I know, only available for the Experimental G5 model.
Dan wrote:
You either mean a magnetometer like the GMU11 (give you winds aloft), or the OAT sensor for density altitude… no worries, read ya 5
You need both for winds aloft. Without the OAT sensor, you don’t get TAS. I would guess that Archer-181 installed a magnetometer from the start. (A G5 EHSI without a magnetometer wouldn’t make much sense.)
Archer-181 wrote:
I installed the OAT probe 12 months later for winds aloft
You either mean a magnetometer like the GMU11 (give you winds aloft), or the OAT sensor for density altitude… no worries, read ya 5
That sounds rather like the Aspen EFD “software fixes” for the OAT reading several degrees off.
Snoopy wrote:
What problems with the G5 did you experience?
For the first few iterations of the firmware, the horizon was often quite inaccurate (it would show a bank of up to 10 degrees in straight and level flight). This was despite good air data and GPS reception. Many of the first series of firmware updates had a changelog item “improved attitude calculation”. With the current version of the firmware I’ve not seen any problems with the attitude display, even when towing gliders (where there’s typically only about 30 seconds from startup to applying power for takeoff and no prolonged taxi). With the original firmware versions, a short taxi would often leave the attitude display showing a 20 degree bank on takeoff when the wings were actually level!
The air data sensors on mine also failed after about 2 years, I sent it in for service, the replacement unit has not had any issues.
