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Glass & Spins

dwschaefer

Active Member
I just completed a phenomenal spin course. It was great!!

However, during the ground work, I was shown a video from the back-seat of an RV-8 with a glass display ...which CLEARLY lagged big-time behind the recovery. The aircraft was back level, blue sky up and the display still showed it to be upside down!

I'm curious for those of you that have glass and spin your aircraft ..is this a "normal" situation .. I haven't tried my GRT AHARS yet ... for such a lag for the display to catch up. I told the instructor I'd research with the experts.

Thanks...

DWS
RV6-A N142DS
"Nerdgasm"
 
Hi there, yes, it's pretty normal for this to happen in my airplane. I have dual Dynon Skyview D700 displays. The PFD takes a few seconds to come back to reality after a spin or other aerobatic maneuvers.

To me it's a non-event because my attention is 99.9% outside the window anyway. I'm not the least bit concerned because the ADAHRS always catches up later, and you can't damage it by flying aerobatics. I would MUCH rather have glass than gyros when doing aerobatics. I hope this helps.
 
My experience is the same as Gash's. The Dynon ADAHRS looses it's marbles pretty quickly. I think the Garmin equipment is probably a notch or two above Dynon in this respect.

Even a roll or two will throw the Skyview out of whack. Not entirely confidence building.
 
That's what I'm thinking. Night or IFR and the autopilot or something else creates an upset. Turbulence, any number of scenarios. Spatial disorientation.

Mistakes happen and one should have a fighting chance to correct the situation.

I think this is a big deal. Very interesting. A thread of its own in the Safety section. All should be advise.
 
So if you're flying IFR with glass and you get into an upset condition what do you do?

Same as any other time flying in IMC:
1. Cross-check,
2. Interpretation,
3. Aircraft control.

If there's a problem with the glass, you'll find it during step one. If the glass has gone wonky, revert to standby instruments (you do have those, right?) until glass regains its marbles.
 
So if you're flying IFR with glass and you get into an upset condition what do you do?

An upset condition is, IMHO, going to have rotation rates much less than a spin, so you do an unusual attitude recovery just like you always do.

One possibility (I might be blowing smoke here) is that if the vibrating gyros in the glass cockpit get confused, the trusty old turn coordinator will be too stupid to get tumbled and will still be usable -- if you can do a partial panel extremely unusual attitude recovery.

It would be fun to go try that all out, but my G3X airplane is not good for spins, and my surgically repaired spine would probably complain a lot on the Gs you could pull in a spin recovery.

On the other hand, if you want to see what your gyros will do, get a qualified person in the other seat (if you're not) and do some frisky maneuvers and see what the instruments do, and look for the chevrons and other symbols when bank and roll angles get big. Just be careful not to overspeed the RV when you're doing those things.

Ed
 
Pilots of yesteryear didn't worry much about spinning gyros. They employed another method said to have a favorable outcome. It's called the "whiskey bottle and duck" method. When caught short of fuel and above a solid overcast... drink the bottle down to half full and use that for attitude and throw out the duck while following him down in a full on spin. We don't need no stinkeen gyros.:)

Cheers,

Hans
 
My wife's grandfather was a B-25 pilot in WWII. He told me a story about the whiskey and duck method! Funny that you should bring this up!
 
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Attitude Rate Limit

Can't say for sure, but the video you refer to is possibly from spin training I did with CE Cavegnaro in my RV-8. Before anybody gets upset about the Dynon Skyview ADAHRS "tumbling", please go read their excellent Pilot's User Guide, Chapter 4, which states; Attitude Rate Limit - Skyview's ADAHRS will operate normally at rotational rates of up to 150 degrees per second in any axis. If the aircraft's rotational rate exceeds 150 degrees per second, as can happen in a well-developed spin or when performing aggressive aerobatic maneuvers, the PFD page will annunciate "ATTITUDE RECOVERYING".......
The Dynon ADAHRS performance in my RV-8 during spins is considered normal ops for the SKyview and not a safety issue (at least for my installation in my aircraft). I perform spins by looking outside the aircraft for situational awareness, not inside at the SKyview. I have done numerous loops and rolls and the Skyview ADAHRS performs perfectly.....unless I exceed 150 degrees of rate change per second. Go look at a typical gyro driven AI and see what is looks like after a well developed spin / recovery and if comes back to life in 2-3 seconds.
 
Before anybody gets upset about the Dynon Skyview ADAHRS "tumbling", please go read their excellent Pilot's User Guide, Chapter 4, which states; Attitude Rate Limit - Skyview's ADAHRS will operate normally at rotational rates of up to 150 degrees per second in any axis.

Dynon's ADAHRS does operate within it's spec; I don't think anyone has said otherwise. I contend that it's not a bad spec, either - just that Garmin spec or actual performance is likely better.

Also, mechanical gyros tumble too.
 
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FWIW: Saw Sean Tucker at his operation last year and noticed both of the biplanes had Dynon D-10s installed. Since I had one I asked how they were holding up and if they ever "tumbled". He said they were totally reliable and he had never noticed any attitude errors no matter what he did in flight.

Don Broussard
RV 9 Rebuild in Progress
57 Pacer
 
I guess it's the legend that won't die...

My grandfather was a B-25 pilot in WWII. He told me a story about the whiskey and duck method! Funny that you should bring this up!

...that a liquid surface (or suspended dice from the rearview mirror) will provide attitude reference in any type of accelerated flight. It just ain't so, else we could rely on our inner ear or seat of the pants to do the same, and we would not be able to pour milk at the top of a loop.

I'm sure it's possible, perhaps safest, to spin down through an undercast and recover once clear, if no standby instruments are available. But your whiskey bottle will NOT be showing you a reliable horizon during that maneuver. Not even close.
 
It's a joke Bill. It was funny back then, and it's still funny now. Nobody is really serious about it. ;)

He also used to tell stories about being over the ocean, half way between Okinawa and the Japanese mainland. Mandatory total radio silence. Then some young guy in the formation would radio: "Who dat?" Then another guy would reply: "Who dat say who dat?" Then another: "Who dat say who dat say who dat?" Finally the old man would get on the radio and yell "Everybody shut the **** up!"

...And an hour later it would start all over again.

Pilot humor. Gotta love it.
 
Or a couple of geese and form up with them.

Besides tumbling EFIS, navigators, like my GTN650, loose lock with the satellites if you roll or pull hard enough to blank out the antenna's view. Knocks out ADS-B since it's the WAAS source, and a sure-fire way to fail your $500 rebate ride.

John Siebold
"No drinking on final."
 
...that a liquid surface (or suspended dice from the rearview mirror) will provide attitude reference in any type of accelerated flight. It just ain't so, else we could rely on our inner ear or seat of the pants to do the same, and we would not be able to pour milk at the top of a loop.

The liquid in the bottle was more for courage than flight attitude:rolleyes: . Having an attitude back then probably accounts for many of aviation's advances.

Cheers,

Hans
 
FWIW: Saw Sean Tucker at his operation last year and noticed both of the biplanes had Dynon D-10s installed. Since I had one I asked how they were holding up and if they ever "tumbled". He said they were totally reliable and he had never noticed any attitude errors no matter what he did in flight.
I rather suspect he flies his most energetic manoeuvers without reference to any instruments... By the time he wants to look at them again they'll have self-righted. I know i've tumbled my D-10A and it's unlikely i'm doing anything as fun as he does in his biplanes... :p
 
Can't say for sure, but the video you refer to is possibly from spin training I did with CE Cavegnaro in my RV-8. Before anybody gets upset about the Dynon Skyview ADAHRS "tumbling", please go read their excellent Pilot's User Guide, Chapter 4, which states; Attitude Rate Limit - Skyview's ADAHRS will operate normally at rotational rates of up to 150 degrees per second in any axis. If the aircraft's rotational rate exceeds 150 degrees per second, as can happen in a well-developed spin or when performing aggressive aerobatic maneuvers, the PFD page will annunciate "ATTITUDE RECOVERYING".......
The Dynon ADAHRS performance in my RV-8 during spins is considered normal ops for the SKyview and not a safety issue (at least for my installation in my aircraft). I perform spins by looking outside the aircraft for situational awareness, not inside at the SKyview. I have done numerous loops and rolls and the Skyview ADAHRS performs perfectly.....unless I exceed 150 degrees of rate change per second. Go look at a typical gyro driven AI and see what is looks like after a well developed spin / recovery and if comes back to life in 2-3 seconds.

Not pointing fingers .. or anything else at vendors ..I specifically didn't mention vendors to avoid 'mine is better than your's' conversations. Just curious about how glass recovers vs. old mechanical instruments. Thus my question.

Thanks..
DWS
 
The engine will quit...

Dear Bob can you tell me why the engine stops? is carburated? Fuel pump was on?

Best Regards

..if the fuel tanks do not have a baffled compartment, to keep the fuel over the pickup tubes. Without this aerobatic mod, the fuel will 'sling' outboard during a spin, away from the pickup tubes, thereby starving the engine.

I think.
 
I'm not quite sure that glass cockpit AHRS tumbling during aerobatics or spinning is a reason to be concerned about the same happening during an upset in IMC.

If that was a serious problem, then no modern commercial aircraft would be flying IMC, as they all have glass primary instruments and glass standby instruments. In simulator training we get them into some pretty major upsets and they don't go blank or tumble, because the gyro rates simply aren't high enough during that sort of manoeuvring.

Spinning is a different issue though, and gyro tumbling after spinning is not unique to glass instruments. During my military flying training I remember conventional attitude gyros being in all sorts of wonderful attitudes after recovery from a spin. They also didn't automatically regain good attitude information after a few seconds. They had to be manually re-caged while you flew straight and level, which you could only do if you were either in visual conditions, or had good "limited-panel" IMC flying skills.
 
Dear Bob can you tell me why the engine stops? is carburated? Fuel pump was on?

Best Regards
Hernan, It is a high compression IO-375 fuel injected. It only happened that one time. I live in Denver and my airport is at 5673" (KBJC 1,730 m) I was doing spins at 10,000' and I believe I had the engine too lean for that altitude. I believe the prop stopped because it is a low mass composite prop but smarter people than me can chime in.
 
I was just afraid someone might believe it ;-)

It's a joke Bill. It was funny back then, and it's still funny now. Nobody is really serious about it. ;)

He also used to tell stories about being over the ocean, half way between Okinawa and the Japanese mainland. Mandatory total radio silence. Then some young guy in the formation would radio: "Who dat?" Then another guy would reply: "Who dat say who dat?" Then another: "Who dat say who dat say who dat?" Finally the old man would get on the radio and yell "Everybody shut the **** up!"

...And an hour later it would start all over again.

Pilot humor. Gotta love it.

My Dad told that story many times. To hear him tell it, the banter originated in the course of 453rd BG operations over Europe. He hated that war and wanted nothing to do with getting into the belly of an airplane ever after, but the man was a bundle of paradoxes, to be sure. My mom surprised him with a tour of a Liberator on static display when he was about 70. He climbed to his top turret position and back out again, looked at her and said, "Sorry, sweetie - it's like a coffin in there..." He was silent the whole drive home. A few years later the vanity tags on his pickup truck bore the message "WHOODAT."

Go figure.
 
I'm not quite sure that glass cockpit AHRS tumbling during aerobatics or spinning is a reason to be concerned about the same happening during an upset in IMC.

I've had the Dynon ADAHRS tumble exactly once in IMC, so it is a potential issue. Comparing an experimental ADAHRS unit from any of the manufacturers to the multiply-redundant, tested-to-h**l-and-back certified equipment used on commercial aircraft may not be a reasonable comparison.
 
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Hernan, It is a high compression IO-375 fuel injected. It only happened that one time. I live in Denver and my airport is at 5673" (KBJC 1,730 m) I was doing spins at 10,000' and I believe I had the engine too lean for that altitude. I believe the prop stopped because it is a low mass composite prop but smarter people than me can chime in.

This happens regularly to me when the tanks are at less than 1/2-1/3 full and I do more than 5-6 turns in a spin. I think the fuel simply moves outboard away from the pickups due to centrifugal force.
 
This happens regularly to me when the tanks are at less than 1/2-1/3 full and I do more than 5-6 turns in a spin. I think the fuel simply moves outboard away from the pickups due to centrifugal force.


Same here. I don't have a flop tube. So the fuel gets pushed to the outside which makes the engine quit after a couple of seconds and the prop will stop shortly thereafter. Happens every time. See:

http://www.spatscheck.com/oliver/Spin.mp4

If I counted correctly prop stopped after about 9 turns engine quits a bit sooner then that in that video which is actually surprisingly long considering that the fuel gets pushed outside pretty much right away. So there is quite a bit of fuel in the system.

The only problem with that is that you have to keep the downline after recovery for a while longer before the prop starts spinning again (starts spinning at about 160mph). So the recovery took about 2000 feet compared to a couple hundred feed after a 3 turn spin. Partially due to the recovery taking longer (2 turns or so) but partially also due to keeping the downline a bit longer . Something to keep in mind in case you try.

As for glass. Yes my Dynon starts tumbling after a small number of turns and recovers in a couple of seconds after leveled. Interestingly my GPS (GPS2020) gives up after 20 or so turns. Now I specifically put my GPS in the wing tip so it works during acro and I can go through the sports man routine without loosing GPS coverage or accuracy. So it's not an issue of line of sight. So not sure why that happens. Hope I don't have a loose connector or something... .

Oliver
 
I've had the Dynon ADAHRS tumble exactly once in IMC, so it is a potential issue. Comparing an experimental ADAHRS unit from any of the manufacturers to the multiply-redundant, tested-to-h**l-and-back certified equipment used on commercial aircraft is a reasonable comparison.
I've had the fully certified standby attitude indicator go irretrievably belly up on a B767, in straight & level flight while still fully powered and with no failure flags.

But of course this is why you have more than a single attitude source, and an independent power supply, whatever aircraft you plan to fly in instrument conditions.
 
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