[grantcarruthers]

Finally got my RV-4 in my hot little hands and am starting to expand the envelope. So question is, how much should I worry about the gyros in the panel for simple rolls and beginner beginner acro. Is there a simple way to vent the vacuum temporarily to deactivate the gyros and will this improve their survival during light acro or would it be worse if they were not spinning and 'rigid'?? Sorry if this is a completely stupid question. The HI doesn't precess at all like the crud I've rented and I'd like to keep it that way.

 

[Mel]

Most modern gyros will do fine in roll. They do not like pitch greater than about 80 degrees, so loops will tumble them.
Disconnecting them from vacuum will not help much. Unless they are cageable, they will still bang against the stops.
If your airplane has not been tested for acro, you will have to put it back into phase I for a minimum of 5 hours. Your operating limitations will give you guidance on this.

 

[JonJay]

Tested for Acro?

Most modern gyros will do fine in roll. They do not like pitch greater than about 80 degrees, so loops will tumble them.
Disconnecting them from vacuum will not help much. Unless they are cageable, they will still bang against the stops.
If your airplane has not been tested for acro, you will have to put it back into phase I for a minimum of 5 hours. Your operating limitations will give you guidance on this.

Hey Mel, not meaning to hijack this thread, but noticed your response on testing for Acro. I was doing Acro almost from day one, but what constitutes testing? I show in my logs what manuevers where performed, but is there more to be done?

 

[Mel]

Hey Mel, not meaning to hijack this thread, but noticed your response on testing for Acro. I was doing Acro almost from day one, but what constitutes testing? I show in my logs what manuevers where performed, but is there more to be done?

Testing is doing any maneuver not already listed.

 

[grantcarruthers]

How much damage is done by tumbling though I guess is my question? As far as testing vs. operating limitations goes I suppose thats a legal answer but is it realistic? I bought the -4 to keep entertained as I take my time building the -8. I don't even know if I have a copy of the operating limitations to tell you the truth!! I just assumed that if Van designed a plane to +6/-3 thats what you get?

 

[gasman]

REQUIRED

I don't even know if I have a copy of the operating limitations to tell you the truth!! I just assumed that if Van designed a plane to +6/-3 thats what you get?

That is part of the paperwork that is required to be in the aircraft. And it might just say..... "THIS AIRCRAFT PROHIBITED FROM ACROBATIC FLIGHT" plus a few other things that you should know.

 

[Mel]

Look at your Airworthiness Certificate!

It states that "Operating Limitations dated xx/xx/xxxx are a part of this certificate." The aircraft cannot be operated legally without the operating limitations. And like Gasman says, there's a very good chance that they might say "This aircraft is prohibited from aerobatic flight." Some people do not request aerobatic privileges.
Also, Van did indeed design the RV-4 to meet aerobatic standards, BUT, Van probably didn't build that particular aircraft!
Gyro tumbling puts a lot of uneven wear on the bearings greatly reducing the life of the gyro.

 

[boomer]

Finally got my RV-4 in my hot little hands and am starting to expand the envelope. So question is, how much should I worry about the gyros in the panel for simple rolls and beginner beginner acro.

What about the digital EFIS's like the Dynon, etc.?

-John

 

[dan]

What about the digital EFIS's like the Dynon, etc.?

-John

If I only had a nickel for every time my Dynon EFIS-D10 was tossed through a roll or loop...

 

[Ironflight]

What about the digital EFIS's like the Dynon, etc.?

-John

That is probably one of the strongest argument for solid-state "gyros" in RV's - they stay happy as clams through whatever you want to do with the airplane! Take it on an IFR cross-country one day, and turn it upside the next - and never worry about messing up the gyro bearings. I doubt I'll ever own a mechanical gyro again....

Paul

 

[mike newall]

Perhaps we have eventually found a practical use for Falcon instruments - fit them, aerobat them, change them on the annual - won't cost much and they won't last much longer in any case

 

[boomer]

That is probably one of the strongest argument for solid-state "gyros" in RV's - they stay happy as clams through whatever you want to do with the airplane! Take it on an IFR cross-country one day, and turn it upside the next - and never worry about messing up the gyro bearings. I doubt I'll ever own a mechanical gyro again....

Paul

Paul, thanks for the reply. What I was really asking is if they tumble during acro. In other words, do they give accruate pitch and bank during acro maneuvers and are they indicateing properly immediately after acro?

-John

 

[Ironflight]

Hi John - now I understand! As far as I can tell, the GRT AHRS and Display Units are accurate all the way through typical maneuvers (rolls, loops, etc). I haven't spent much time "head's down" during such events, but at a glance, they seem to be accurately portraying the attitudes.

Paul

 

[boomer]

Hi John - now I understand! As far as I can tell, the GRT AHRS and Display Units are accurate all the way through typical maneuvers (rolls, loops, etc). I haven't spent much time "head's down" during such events, but at a glance, they seem to be accurately portraying the attitudes.

Paul

Thanks, in a previous life I did a good bit of acro type stuff IMC when the ADI was the only thing available, so I like to sneek a peek.

-John

 

[gmcjetpilot]

Take them out? Put them back in?

Finally got my RV-4 in my hot little hands and am starting to expand the envelope. So question is, how much should I worry about the gyros in the panel for simple rolls and beginner beginner acro. Is there a simple way to vent the vacuum temporarily to deactivate the gyros and will this improve their survival during light acro or would it be worse if they were not spinning and 'rigid'?? Sorry if this is a completely stupid question. The HI doesn't precess at all like the crud I've rented and I'd like to keep it that way.

My first RV was a dash 4 and I put a full panel of gyros in 2-vac 1-elec t&b. Over many years of doing acro I overhauled all three gyros (including the elec T&B) and went through two vac pumps. I did a ton of acro. In my opinion there was a direct relation to the early demise of my gyros and acro. I think the Vac pump did no like the acro either. I ended up taking all of the vac gyros and pump out for local flying and covered the holes in the panel. I left the hoses, filter and regulator in. I could reinstall the whole set-up in a hour or so. So my solution was to take the vac gyros out and put them back in when needed. I still did some acro with the gyros in. When flying cross country I'd put them back in. However once flying is some scud with out the gyros (except the elec T&B), I really wished I had them in. Bottom line don't worry about it, but plan on wearing them out faster. Faster? 10% or 50% less life who knows. I think it depends on many factors. Gyros are funny delicate things. Even hard landing can toast a gyro, as well as sitting too long on the shelf with out being run. I'm not recommending taking them in and out, but that is almost the only solution if you don't want to do any acro damage to them. If you just cut the Vac air they will flop around and probably do more damage.

 

[grantcarruthers]

Thanks, that's the concise 'been there, my experience is...' answer I was looking for.

PS, couple of rolls went quite well the other day. By the book, literally. It'll be a few more before my brain can totally keep up with the scenery. Kind of like my first spins (not in the RV, back in primary training) where you're left with that "what just happened" expression!! Fun, controlled, but way weird when 239.9 of your 240 hours are well under 60 degrees bank.

 

[Bill Dicus]

Acro, instruments

We've flown routine +6 and -4 G's for 25 years in our Pitts and the turn and bank still works fine. Have heard repeatedly that AI's and DG's don't do well with frequent acro. Am going with EFIS in the -8 for this and other good reasons. Check Dan Checkoway's site (hope spelling is right). He has Dynon I think and it works fine with most acro. Just playing with mine (in my hands) I can exceed pitch or roll limits and the unit greys out but still gives attitude indication very close to reality. The ACS is apparently tolerant of higher rates and other EFIS's each have their own limits. No worry about mechanical gyros. Bill