Aircraft 'G' meters

[Tomo]

This has been on my mind the last little while, and the Drifter crash just recently made it even more clear to me.

 

How do you know what G's you're pulling?

 

How do you know if you're not going over the limit?

 

All the questions would be answered if you had a G meter, but how many aircraft have them? not many, unless aerobatical I presume.

 

The thing that bothers me, when you first start out, you can distinctly feel the G's, then you grow accustomed to them, and they don't ''feel'' as bad as what they could be. I know that from my own experience.

 

Not sure about the Drifter exactly, but I know the J120 is +4 -2 G and you don't go over that. Now 4 G isn't much... I mean, it would be for a beginner, but I bet you - someone with a handful of hrs wouldn't really cringe to much at 4 G. Can you see what I'm getting at?

 

I remember doing steep turn lessons, and the small amount of G's pulled on that felt a lot, now it's nothing... and to pull equivalent G's to what it used to "feel" like, would be a lot more now.

 

Is this what is causing aircraft structural failures? I mean, you can see how it would happen quite easily.

 

Can you buy portable G meters? If you could, (I'll find out when I can) I will invest in one for sure. Just to see what I'm actually pulling, and I bet I'll be getting closer to that limit than when I first started.

 

Another concern, who knows their safe 'turbulence penetration' speed? The maneuvering speed? Something at 100kts will pull a lot more G on a pull up/large control deflection then something doing 60kts. Try going around a corner on the road at 60klm, then come back and do it at 100klm. Any difference?

 

I hope I'm not just blabbering on - but this is something I've been thinking about quite a lot, as I said above. We all know what the aircraft can handle re G wise, but do we know if we are actually exceeding it?

 

Food for thought.

 

 

[Spin]

Tomo, unless you're extremely fit and used to pulling G (think aerobatics or fighter jock), by the time you're approaching 4G the world is starting to go a little grey on you. I don't think you're going to get there by accident. I take your point though about turbulence penetration, the forces increase pretty rapidly with speed.

 

 

[Vev]

Hi Tomo,

 

Not sure of the a/c you hire have a EFIS fitted ... many of these have G meters as part of their fuction... this is not often known.

 

Cheers

 

Jack

 

 

[Vorticity]

You can buy g meters from mgl or similar or even put one on an iPhone and track the g that you pull through your flight.

 

Honest though tomo, you shouldnt be too worried about breaking a drifter. The one at dalby is a nice machine, has not been upside down in the surf and isn't constantly aeroed. Most of us fly such sedate flight profiles that it just isn't an issue in newish type aircraft such as the jab or a tecnam.

 

Don't worry about the g meter, and keep listening to that little voice in your head like you did in inglwood.

 

 

[winsor68]

When it comes to buying a second hand aircraft how can you tell what sort of forces the aircraft has been subject to? Is there any economical way to check the spars and flying wires?

 

 

[Mazda]

I typed a reply and it disappeared! An abbreviated version.

 

G meters are great but they are not always the answer.

 

If you fly around and do level steep turns of less than 60 degrees, you won't have a problem, that's 2gs. To do a loop in a Citabria takes about 3gs. In a competition you might want a bit more than that.

 

But if you are flying around pulling 4gs while not doing aeros you are probably up to no good or in a bit of trouble.

 

As for the pilot, pulling 4gs for a second or so is not the same as a sustained 4gs. Even if you pull well over 4gs for a second or so the pilot is unlikely to grey out.

 

Also consider transitional G - going from negative to positive gs is not kind on the pilot, or on the airframe. Imagine a rag wing aircraft (with wires and tubes) bunting over, with zero or negative G, the wires etc are slack. If you suddenly apply positive G, to the wires it is like cracking a whip. The rapid onset of G can result in structural failure and the G-meter may not show any over stressing. An all metal aluminium riveted aircraft with loose rivets can suffer the same fate. A pilot going from negative to positive G is much more likely to suffer the effects of G, including G-LOC.

 

One important thing to consider is rolling G. If you are rolling, you should only pull G equivalent to 2/3rds of the published aircraft G limit to avoid overstressing the aircraft. So if your aircraft limit is +4g, when rolling if you pull more than about 2.5g, you are exceeding the G limit of the aircraft. A G meter won't help you there either.

 

Aerobatics training goes through all of this.

 

So please don't muck around without appropriate training. If you want to pull g and fly aeros, get the training and do it properly. Otherwise stay within the normal limits.

 

 

[Guest basscheffers]

What Mazda said...

 

Also: My SportStar supposedly can do +6/-4, but as at least one unfortunate soul (well, idiot) could testify if he didn't have a garden on his belly doing that regularly and/or sustained will end in tears.

 

Just because an aircraft has a specific limit, do not assume it won't fall apart as long as the meter says you were always under. Even some aircraft *designed* for aeros and high-G have a severely limited airframe life when doing regular aerobatics in it.

 

 

[Tomo]

Thanks heaps for the feedback guys...

 

I believe it's a worth while thing to understand, and as Mazda mentions about the roll, you don't realize what you could be inflicting on the aircraft if you fly out of the normal envelope.

 

 

[sseeker]

If you have a Dynon D10A in your aircraft, this has a G meter built in (pretty sure)

 

 

[country kid]

your proberly right essentialy 1-2 g is nothing to me any more but when i first started flying it was noticable but know i dont even flinch. it would be a good idea or after market g meters arent dear, my mate has a drifter but he dosent consider it necassary. its wire braced rated +6 -4 i think he said?

 

 

[Admin]

When I took delivery of my brand new CT that had the twin Dynons I checked them and found that in the pre-delivery testing the aircraft had got to 2.1g which was great to know - when I sold it the max the aircraft had got to was still 2.1g

 

 

[monty]

your proberly right essentialy 1-2 g is nothing to me any more but when i first started flying it was noticable but know i dont even flinch. it would be a good idea or after market g meters arent dear, my mate has a drifter but he dosent consider it necassary. its wire braced rated +6 -4 i think he said?

Hi guy's, just a bit of info on the drifter. I have an Ausflight Drifter and they are rated at +4.06 and -3.00 with no more than 60 degrees bank angles and under no condition aerobatic manoeuvres, including spins. this is from the manual.

However I have done spins and such only so I know what to do if an emergency does happen. You do need to know what the plane can and can't do. I am only a novice at flying so I am not sure of the affects of G's but figure that when your eye sockets are popping thats too fast.

 

I have the Ausflight Austrailian Drifter Operators manual on my computor if anyone has a Drifter (or not) and would like a copy emailed to them.

 

Just my 2 Cents worth.

 

Monty

 

 

[dazza 38]

Hi Guys, i would like to add to this, Bass and Mazda have covered it. I would like to add a bit more. This is from memory- The F111, (and most if not all military jets like it )has G metres that have a are non-resettable recording (like a hour metre).The meters are recorded and placed in a maintence record etc. If the a/c has sustained x amount of G's, their are inspections carried out IAW publications.The hornet (apparently never worked on them) have a points system, where as when they get to a certain amount of points, inspections are carried out. As both of these a/c got older, individual a/c started having restrictions place on the Ie- how many G could/can be placed on the a/c.A fair few F111's had g resrictions placed on them before i got out of the RAAF, 1998.

 

Aerobatic a/c that are built realy strong but can only sustain that g loading for a certain amount of time. One of the strongest is the yak 52, with that spar mods that were supposed to have been completed by 1985.The yak was designed to be able to sustain a load of 7 G's for 2000 hours(continuous).Guys that is alot, and for a long timeframe.Getting back to the drifter or other a/c which are non aerobatic but are stress to eg- +6 -4.As discussed and covered above by our friends above.G meters are a good idea, along as people dont used them incorrectly and think that because my a/c is stressed to eg +6 or what ever,i can do that day in day out.That is not the case. I know this is long winded and we have gone through this a while ago, on another thread but people still keep dieing.I wish that people who want to do aero's, do in a certified GA aircraft with a certified instructor until signed off.Thank You.

 

Ps- sorry for highjacking your thread abit Thomas.

 

 

[country kid]

i would love to have a read of that manual monty i dont have as drifter personaly but i use my mates alot and if things work out want to get one :D if you could foreward it to me my email is [email protected] that would be great

 

 

[Tomo]

Just for your interest, you can download Maxair and Austflight Drifter POH's here.

 

Thanks guys for your input above.

 

 

[monty]

Thanks Tomo, I didn't know where to download it. I got mine from a friend.

 

Dave if you have any trouble let me know and I will email it.

 

Monty

 

 

[Guest Cloudsuck]

After owning an aerobatic plane fitted with a G-Meter, I now always have one in my aircraft. I fitted one to my Tecnam when it was new and have never pulled more than 3G but regularly pull 2G in steep turns, dives etc.

 

 

Unless you are doing aeros all the time, pulling 4G will never go unnoticed by the average punter. As Mazda said, if you are pulling 4G, you are being naughty or in trouble. I used to pull to 4G when doing loops in the Yak. And yes, rolling G is the one to be real careful of.

 

 

It has been my experience that pilots who have never pulled G always think that they are pulling 4 when they are actually only pulling 2. I am a bit of a G pansy and 4G is plenty enough for me. I have felt 5G in an L39 Albatross and it was not comfortable. I saw a mate do a routine in a YAK-50 one day and when he landed, the G-Meter was pegged at 9G.

 

 

[Tomo]

Cloudsuck: what type are you using? is it portable or relies on aircraft power source - ie mounted in the instrument panel?

 

Also when I said 4g, I was just making a point, I'm sure I would never get there! But it is true how you get more and more used to something so to make it still feel the same, you often get further into it.

 

Copy the fact that you shouldn't rely on anything other than your training a lot of the time. And a G meter isn't going to save you, but it'd be pretty interesting how much you do pull on some occasions.

 

 

[Guest Cloudsuck]

Cloudsuck: what type are you using? is it portable or relies on aircraft power source - ie mounted in the instrument panel?Also when I said 4g, I was just making a point, I'm sure I would never get there! But it is true how you get more and more used to something so to make it still feel the same, you often get further into it.

 

Copy the fact that you shouldn't rely on anything other than your training a lot of the time. And a G meter isn't going to save you, but it'd be pretty interesting how much you do pull on some occasions.

Tomo, this is a good thread you have put up. And you are right, pilots can get G-Fit. The one I'm using is not powered and is simply a mechanical unit (Photo attached). I prefer this over the electric ones. I have a mate with an electric one in his Savannah and he is surprised at how he never gets over 1G:laugh: I think a G-meter is a pretty simple and good addition to any aircraft. If you have ne ver used one, you will be surprised that how, in really head banging turbulence when you think the wings are going to come off, you are only hitting 1.5G.

 

There is a G-Meter app for the iPhone. It seems to work correctly.

 

 

 

[Guest Walter Buschor]

These are all god comments.

 

I reall don't know like most of us how many g's we are "pulling" when doing this or that. I do remember though that I did pull up to 6.5 G's for brief periods when fling the Decathlon. This happened on more than one occasion. It is very easy to do and yes " one does grey out " but it is only for a split second. In normal flying though i have never had anything that feels more than about 2 g's no matter what I do. To reach 4 g's would really take something silly or deliberate .

 

If we fly within our parameters I do believe we are safe and a G meter is not required. To be honest If at my age I tried Aeros again I do feel I would not be up to it for long. Age does play a part. Even at 24 I used to be "wasted" after 1 hour. I'd hate to think how I'd feel at 49....

 

Come to think of it I'd give it a miss .

 

As most of us are getting on a little aero's probably don't rate very high.

 

If we use our panes as they are ment to be used a G meter n my opinion is a waste of time exept that id just might encourage someone to test the limits of the AC.

 

Don't fit it nd remove temptation.

 

Fly safe

 

Walter

 

 

[Guest rocketdriver]

If I remember correctly, if the G meter sensor is not mounted at the C of G it will overread due to the moment arm .....

 

 

[djpacro]

We all know what the aircraft can handle re G wise .....

Well Tomo, after reading this thread I am pretty sure that not everyone knows what their aircraft can handle.

........ but do we know if we are actually exceeding it?

To add to the previous useful comments - some structures give signs of overstressing such as wrinkles in the metal skin or changes in wing rigging - when the limit load has been exceeded but at less than the ultimate load which is 50% higher. Of course, the owner won't be impressed as it will be expensive to fix. Something to add to your pre-flight check if appropriate.I always keep a significant margin below the limit load factor when doing aerobatics to allow for misjudgement or an unexpected gust.

 

Indeed.

[jetjr]

If you have a Dynon D10A in your aircraft, this has a G meter built in (pretty sure)

All Dynon EFIS have G meter, need to put it up as option on top LHS of screen, you loose TAS and other more useful stuff though

 

 

[Captain]

I have the G-meter active on the screen of my Dynon 180 and have never seen more than 1.6 +ve or 0.9 -ve.

 

But then again, I just fly it like I was taught to.

 

Maybe I should make a You-Tube Video or two, and ramp it up a bit.