Back Up ASI

[Skippydiesel]

Hi All,
My new Sonex has an all digital panel - have been thinking - what if I have a major power failure to the panel & everything goes black ? True its an unlikely scenario, especially as I already have a back up battery for such an occurrence. BUT WHAT IF ?
Seems to me I can pretty well fly the aircraft without any instruments - just attitude & power BUT once I get into the circuit/start to slow for a landing, everything MAY start to get a wee bit stressful.
What instrument(s) might improve the situation? Do you agree that an ASI is the minimum that I would need to ensure a safe landing?
I have very limited panel space, so I think I will limit my back up ASI to 57mm (2 1/4")
The important speeds will be those that assist with landing, so the minimum should be 35-110 Knots. Most gauges operate best in the mid range, so a gauge that indicates 20-120 knots should be just about right.
So what would you recommend?
So far I have looked at;

SWIFT 10-06293
LXNAV Airdata Indicator
Falcon ASI120N-2
Midcontinent MD 25-160
UMA 16-211-120

[pilotyoung]

I just put a new all digital panel in my Onex. I have been flying an RV-12 with an all digital panel for 4 1/2 years. My friends sometimes ask me what I am going to do if the power goes out. I tell them, Look out the window, fly the airplane, and land it somewhere, hopefully on an airport.

When I used to teach students, before I would let them solo, I would cover up the six pack of instruments and tell them to fly the pattern and land. The first reaction was I can't, I don't have an airspeed indicator or an altimeter. I told them fly the same attitude and power settings you have been flying. You know those, fly them. I never had one crash.

So I am totally comfortable flying an all electric airplane. If you are not, get with a CFI and have him turn off the digital instruments just before you enter the pattern and land. Do it several times and it will give you confidence. If you are still not comfortable, add an airspeed indicator.

[GraemeSmith]

I just put a new all digital panel in my Onex. I have been flying an RV-12 with an all digital panel for 4 1/2 years. My friends sometimes ask me what I am going to do if the power goes out. I tell them, Look out the window, fly the airplane, and land it somewhere, hopefully on an airport.

When I used to teach students, before I would let them solo, I would cover up the six pack of instruments and tell them to fly the pattern and land. The first reaction was I can't, I don't have an airspeed indicator or an altimeter. I told them fly the same attitude and power settings you have been flying. You know those, fly them. I never had one crash.

So I am totally comfortable flying an all electric airplane. If you are not, get with a CFI and have him turn off the digital instruments just before you enter the pattern and land. Do it several times and it will give you confidence. If you are still not comfortable, add an airspeed indicator.

This is excellent advice.

You don't see your average Certificated aircraft come with an extra ASI or any of the other instruments in the 6 pack. We don't fly a Sonex with two engines (though we DO have dual ignition systems). It's a weight/cost/risk analysis. Which is not to say that you can't decide to put another ASI in if you bend your risk analysis that way if you are so inclined.

[Onex107]

My AOA/ASI reads from 70 mph to 0 with stall speed indicated at the beginning of the red area. Green, yellow, and red aeras on a differential pressure gauge. The probe is non-electric and home made from internet plans. A friend has made 3D drawings of the probe and makes them on a 3D printer. It even makes the pipe tap in the tubing connections. I use the AOA every time I land. It's in my line of sight on the left top of the panel. If you practice tight 180 degree turns you will be surprised how close you come to stall in a 2G turn. It's the only instrument necessary , and will help you make better landings. Wouldn't fly without one. Total cost about $75.00

[daleandee]

My AOA/ASI reads from 70 mph to 0 with stall speed indicated at the beginning of the red area. Green, yellow, and red aeras on a differential pressure gauge. The probe is non-electric and home made from internet plans. A friend has made 3D drawings of the probe and makes them on a 3D printer. It even makes the pipe tap in the tubing connections. I use the AOA every time I land. It's in my line of sight on the left top of the panel. If you practice tight 180 degree turns you will be surprised how close you come to stall in a 2G turn. It's the only instrument necessary , and will help you make better landings. Wouldn't fly without one. Total cost about $75.00

I agree that a pilot must be able to fly the plane without a reference to instruments. Having said that, what is said here not only answers the question asked, but gives not only a backup to the ASI but another really neat tool in the panel and something that just may, in an emergency situation, keep a pilot from stalling & falling.

I've installed an LRI (Lift Reserve Indicator) on the last two Sonex aircraft I have owned and I believe they are worth their weight. I also have the mechanical type and on my current plane it has been flawless for 10 years. Highly recommended!

Here's an approach (during flight testing many years ago) and you can see it on the left of the panel:

https://www.youtube.com/watch?v=WjA7JDJVKeQ

[Rynoth]

I will echo sentiments above on adding mechanical AOA or LRI to your panel. It will not only provide you a backup for airspeed in the slow flight envelope, it will provide you with additional information that's extremely useful in all low-speed/high-aoa stages of flight. In other words, it's BETTER (and cheaper) than a backup Airspeed indicator.

Here's a video I made awhile back demonstrating my LRI.

https://youtu.be/7aVS91ogf1c

[Scott Todd]

This has become my new pet peeve during instruction and flight reviews. LOOK OUT THE WINDOW! The attitude of the airplane will tell you everything. Practice it a bit. The nose should NEVER go above the horizon until the flare. If its level, speed is good. If the nose is below the horizon, you have energy to spare. If the nose is above the horizon, you better be flaring for landing. If your Space Shuttle panel quits, don't try to land on that 1000' foot strip unless you have done is hundreds of times without reference to your ASI. Proper training and a little practice should be able to talk you out of back-up instruments. And our stuff is pretty reliable these days...

[DCASonex]

One other reason for an old style mechanical airspeed gauge (and or LRI) On my GRT Sport SX, the large numerical airspeed display that immediately catches one's eye on a quick scan, updates too slowly for a Sonex. It does have a tiny white arrow that moves up and down the linear scale in real time, but you have to look for it. I use my old mechanical airspeed indicator on all landings (and an eye on the LRI.)

David A.

[Skippydiesel]

Great responses, my thanks to you all.

A few months back, I had been considering an A of A - I will now revisit that subject.

To the advocates of flight without reference to instruments:
Some of your responses lean toward normalising (arm chair response) an emergency situation - non of us know for sure how we will react (that's why its an emergency).
In my view having a still functioning instrument(s) will greatly assist the pilot to achieve a good outcome.
Most of us, who have accumulated a few flight hours, can fly our aircraft without reference to the panel (when the aircraft is performing as expected) but we ourselves are not "configured" for flight so rely on artificial senses/instrument to achieve this state.
Try to put yourself in the situation where you have no flight instruments (may have additional problems), the need to make a safe landing, possibly into a paddock, which could include a tail wind component - a functioning flight instrument ASI or AoA might just be the critical factor in a survivable or not, result.

[Bryan Cotton]

Some of us have had airspeed failures and survived. I had a pitot cover freeze on a C140 once. My L33 Blanik used to frequently get water in the system. It's not hard to deal with as long as you are not IFR.

The probability of a dual emergency, loss of airspeed AND having to land in a paddock with a tailwind is probably extremely remote.

With that said, if you want it, and it makes you more comfortable, by all means put redundancy in.