Back Up ASI

[pfhoeycfi]

I put a backup MGL ASI/ALT in case I lose my efis or all power and I can switch it from the main bus to a 9v battery with a panel mounted switch. I slso have the reserve lift indicator.

[Skippydiesel]

Bryan, I am a dedicated convert from GA to Recreational Aircraft Association Australia (RAAus). Did some flying in a Citabria recently - felt like flying a tank.

My personal view of RAA class aircraft is that the KISS principal should be, wherever practical adhered to. Some RAA pilots seem to try and get their aircrafts level of system redundancy up to or better than GA - I don't understand this (unless its a bragging issue). BUT where a cost effective nil impact on performance safety enhancement can be implemented, I tend to go for it.

My new Sonex has come to me with a level of systems sophistication I never aspired to - not suggesting for a moment that I will undo the "package" I have purchased.

I have researched installing an A of A compatible with my Dynon - seems to be a simple cost effective enhancement that would improve my aircraft safety, particularly when attempting a landing on marginal field. Unfortunately the systems I have looked at would require significant changes to my pitot mounting - so something that may happen in the future.

The installation of a small analogue ASI, cost not too different from the A of A mast, will, in the event of a Dynon failure, give me all the information that I might need to get me down & stopped all in one piece. In the short term I think this will be the way I will go.

As for finding oneself landing down wind - most of my flying is over heavily treed, undulating to precipitous, terrain with only the occasional small field. An engine out would see me looking for the open space that I felt I could put down in with the greatest chance of my survival and secondly least damage to the aircraft - this could quite easily involve a down wind landing . When I fly out west the country opens up into larger flatter terrain, infinitely more options for a successful "out landing" I could even be picky about which 1000 acre field I might like to put down on.

[Onex107]

There are plans for a standalone AOA on the internet. It does not use your pitot and does not use power. I built my probe out of scrap alum. The only expense is a differential pressure gage, less than $100 here. It does have to be mounted somewhere easy to see when landing. After 350 hours in my Onex I wouldn't fly without one in any airplane.

[onex28]

Hi Morris, what degree do you have your AOA SET AT?

David W

[Sonex1517]

There are plans for a standalone AOA on the internet. It does not use your pitot and does not use power. I built my probe out of scrap alum. The only expense is a differential pressure gage, less than $100 here. It does have to be mounted somewhere easy to see when landing. After 350 hours in my Onex I wouldn't fly without one in any airplane.

You can find a write up of the LRI here

https://img1.wsimg.com/blobby/go/e83c7c ... 4222140376

https://sonexfoundation.com/safety-%26-education

[Onex107]

Hi Morris, what degree do you have your AOA SET AT?

David W

The angle of the probe is adjustable. It's mounted on the inspection plate on the left stub wing. I don't remember exactly but it's somewhere around 53 degrees I think. I adjusted the angle until when it stalled the gage was just inside of the red area. This is 46-47 mph. The gage comes off the peg at 70 so the green and yellow areas are used primarily on approach and landing. But, doing high speed turns, 360's, 2 G's, you come very close to a stall also.

[Skippydiesel]

With Reference to the A of A Plans, Page 10, Drawing

1. Why is the mast angled forward?
2. The two inlet holes seem (from the drawing) to be aligned - same forward location and parallel to air flow ?
3. If my observation of 2 is correct, could the mast be vertical?

[Onex107]

The holes are parallel but located on 45 deg. surfaces. When the wing increases it's angle of attack, the pressure on the holes unbalance and the differential pressure indicates how much angle there is. When the wing stalls, the pressures are the most different.

[Skippydiesel]

The holes are parallel but located on 45 deg. surfaces. When the wing increases it's angle of attack, the pressure on the holes unbalance and the differential pressure indicates how much angle there is. When the wing stalls, the pressures are the most different.

Have you looked at other A of A's - The Dynon doesn't require a 45 degree angle surface but if memory serves the lower port is set at 45 degrees to the upper.

[onex28]

Thanks Morrie, I’ve started at 60 degrees and will drop to 53. I shortened my wingtips (19 feet wingspan now) so my adjustment may be slightly different than yours. Now I have to find out why my ADSB stopped reporting altitude.