Ragsf15e

201 windscreen and lasar cowl closure. 3 blade prop to negate those.

You’re within a knot of me. I appreciate that you did the 3 way speed test instead of just saying you get 175mph TAS based on your Aspen/G5/430W or whatever. Try same power settings at 6500’ (will be more fuel flow). Likely hit 150.

I think you did real good! Even with the 530W. The screen is plenty big to use for weather and traffic, you got lpv approaches, and it’s super easy swap to the Avidyne when you’re ready. The gtx345 is great too with Bluetooth to your favorite flight apps. Plus backup AHRS ADI... which for you is #4 so maybe a little overkill.

Yep, they publish gross, but it definitely changes. Mine is 100mph for my f though... surprised yours is 107mph? Thought our airplane would be same-2740 gross weight?

Until you have to get behind there... I can’t get to a damn thing behind my panel! I was just drooling over the access you have in those pictures!

Definitely agree, but nobody else seems to understand this! The 4 way runs are close if there isn’t a real strong wind. I usually do both and find them within 1 knot so the 4 way is probably close enough if it’s easier to understand. The 4 way will always give a slightly higher speed because the wind drift is being added to your forward speed. It’s slight, but it’s there.

Definitely agree with your analysis of horsepower, but I think the huge variability shown here is from differences in drag. Especially from misrigging, gear not tucked, franken-antennas, etc. at our cruise speed, drag is at least as important as thrust... maybe they’re equally important?

Only 165? In the decent from cruise, I’m usually in the 180s or better!

Can of worms been opened with a speed topic on Mooneyspace. Luckily we’ve never discussed this topic before...

Thats a fast one. Is that with 4 way tests or computed with your indicated as, altitude, temp, etc?

I agree, but he was light in all those tests. 1 person, no bags. I can notice several knots when light. Honestly I use the 430w TAS to compare to my own 4 way tests and it’s usually off by several knots. My IAS is 5 knots higher than it should be. The correction to CAS takes out about 2 knots of that error. Best altitude for me is around 6,500’ DA. Ill be pushing 149-150ish. Mpg suffers down low though.

Mine is very similar to yours but with a 3 blade speedbrake. I’m usually 142-148kts ROP between 7-10,000’ density altitude. Depending on density altitude and weight. If you’re cruising at 10,000’ in socal, what’s the da? You’re losing some speed up that high. Also, take the 5 minutes to do a 4 way gps test. You’re using your indicated airspeed to compute TAS and the IAS is likely off by a few knots.

New guy just stumped Mooneyspace?! Even Doc?! What’s this world coming to?

I’m happy to close this one out with a solution and a lot of learning. Oh, and an AMU or two thrown out chasing the wrong culprit. The problem started with a low bus voltage, around 13.2, but sometimes 13.5, sometimes 12.9. Relatively variable during flight. Looking back through engine monitor data, it has been slowly declining on average for 2 years. Before that, it was solid at 14.0. Mechanic suggested replacing alternator at last annual so I did. Brushes were worn. I trust him very much on engine/cylinders/flight controls... in the future, I’ll do much more homework with electrical issues. No change with alternator. Lived with it for a while but it was declining. Tried to use Zeftronics troubleshooting guide but needed just a little more specific help as I had no experience troubleshooting electrical. Now I do. Talked to different mechanic. Talked me into new voltage regulator because “that’s cheaper than paying us for a few hours of troubleshooting.” No change in voltage. Although now I have a spare Zeftronics VR if anyone needs one. Decided to try my own hand. Bought $20 voltmeter at Lowes. Spent couple hours quality time with airplane apart. Cowl off, battery/avionics compartment open, instrument panel cover off. Identified two issues... Master Switch on my airplane is a single switch, dual pole. Not only does it Power the master relay, but it connects the alternator field wire. It isn’t the later model split switch. My switch is getting old. Voltage drop across it is the maximum allowable on the Zeftronics troubleshooting guide, .5 V. There is absolutely no access to change that switch without tearing out the panel. It’s on the list for next time the panel is apart. The other issue was the bus voltage was good (matched battery relay) but power input to the VR was .4-.6 volts lower. Found out the “alt field” circuit breaker was actually the power for the VR. Tested drop across the CB... .5 volts. New circuit breaker cost me $20 on spruce. It was accessible from under the panel so I changed it. Just flew it... 14volts and rock steady! Be aware, the electrical diagrams in the maintenance manual are model and year specific. I was surprised to see that both my field wire and my VR power wire went back behind the panel and then came back to the engine compartment. Also, that “battery master” switch on older models also cuts off the alternator field, so could be an area for resistance. They are cheap switches if you can get to them. Anyone want a working alternator with worn brushes or a gently used Zeftronics VR??

+1. Here’s a picture.