CoolGuy
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Largest Obstacles To Overcome To Build The A380

Fri Mar 30, 2007 12:45 pm

What were some of the greatest challenges from an engineering standpoint to build the A380? I'm impressed that it was actually accomplished with a wingspan of only 80m (in order to fit into the 80x80m box). Anything else? I know it's an amazing piece of work from an engineering point of view, but why?
 
lehpron
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RE: Largest Obstacles To Overcome To Build The A380

Fri Mar 30, 2007 7:45 pm

Personally, I think the business case would be a bigger obstacle, all companies do research to tell whether something is worth investing in. Airbus would have had to look at it from both the perspective of using current technology or being forced to develop newer technology to bring costs down of the estimated development. If the item costed too much that they couldn't sell enough, it would be a problem. I would suppose Airbus determined that throughout the lifetime of the then-A3XX a certain number of planes could be sold which justified the launch of the program. All companies do stuff like this, whether it is your favorite sodapop or even a tv show.

Quoting CoolGuy (Thread starter):
I'm impressed that it was actually accomplished with a wingspan of only 80m (in order to fit into the 80x80m box).

If we limit ourselves to tube-wing designs, then yes it is impressive. But from what is known about the BWB and other concepts, we have quite a bit of evolving to go.

IMO, it is a bad thing when technology doesn't progress just because not all of it is used practically. By the time current technology cannot keep up, the newer tech would cost way more. This is why I believe companies should bite a bullet more often instead of bitch about their bottomline and ROI's.
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CF188A
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RE: Largest Obstacles To Overcome To Build The A380

Fri Mar 30, 2007 8:42 pm

Business again.... to manipulate airports and get A380 ready gates. Airbus could not just assume that every International Airport would just welcome it with open arms.

Secondly, weight. Wasn't there a big thing about how many airports needed to strengthen the first 1000ft of runway due to the impact upon landing?
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CoolGuy
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RE: Largest Obstacles To Overcome To Build The A380

Sat Mar 31, 2007 1:14 am

Quoting CF188A (Reply 2):

Secondly, weight. Wasn't there a big thing about how many airports needed to strengthen the first 1000ft of runway due to the impact upon landing?

I thought the A380 will have less of an impact because the weight is spread out over more landing gear (less per wheel).
 
Analog
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RE: Largest Obstacles To Overcome To Build The A38

Sat Mar 31, 2007 2:05 am

Quoting CF188A (Reply 2):
Secondly, weight. Wasn't there a big thing about how many airports needed to strengthen the first 1000ft of runway due to the impact upon landing?

I think it's more an issue of the load-bearing widths of the runways & taxiways.
Check out this old presentation (MS PowerPoint): A380 @ ATL
 
cymro
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 05, 2007 6:22 am

Quoting Lehpron (Reply 1):
If we limit ourselves to tube-wing designs, then yes it is impressive. But from what is known about the BWB and other concepts, we have quite a bit of evolving to go.

What is BWB short for?
 
oly720man
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 05, 2007 7:22 am

Quoting Cymro (Reply 6):
What is BWB short for?

Blended wing body



http://oea.larc.nasa.gov/PAIS/BWB.html
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Jetlagged
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 05, 2007 8:45 pm

The biggest technical obstacle for the A380 was keeping it's weight down. Then there was the logistical nightmare of transporting the huge sub-assemblies from factories all round Europe to Toulouse for final assembly. Now there is the grossly under-estimated electrical wiring production problems, not least because of the carte-blanche given to interior designers for different airlines.
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Starlionblue
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 05, 2007 10:13 pm

Quoting Jetlagged (Reply 7):
Now there is the grossly under-estimated electrical wiring production problems, not least because of the carte-blanche given to interior designers for different airlines.

Hindsight may be 20/20, but I would say the decision to use incompatible versions of CATIA to design the wiring and the rest of the aircraft was not very wise.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
saintsman
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 05, 2007 10:45 pm

I'm sure the new technology cost a bit to develop however it may have a good chance of being used on the A350. Spend on one project, save on another.
 
cymro
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RE: Largest Obstacles To Overcome To Build The A380

Tue Apr 10, 2007 7:39 am

Quoting Oly720man (Reply 6):
Blended wing body

thanks Oly720man
 
A320ajm
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 12, 2007 9:26 pm

I think it would have been the physics. Is it possible to build such a big aircraft an lift it in the sky? For example, the A380 will have a larger air resistance than other aircraft. This could have affected the terminal velocity, stopping the aircraft from getting enough speed to take off or cruise. This would have also affected the maximum speed.
Feel free to criticise me, i am only 15, but i really like physics.
Thanks
A320ajm
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Starlionblue
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 12, 2007 9:43 pm

Quoting A320ajm (Reply 11):
I think it would have been the physics. Is it possible to build such a big aircraft an lift it in the sky? For example, the A380 will have a larger air resistance than other aircraft. This could have affected the terminal velocity, stopping the aircraft from getting enough speed to take off or cruise. This would have also affected the maximum speed.
Feel free to criticise me, i am only 15, but i really like physics.

First of all: Keep loving physics!

But I shall criticize.  Wink The aerodynamics of tubes with wings is well understood. Aerodynamically, the 380 is "just" a scaled up version of the airliners in service today. Double decker designs have been proposed for decades. The main problems have been other than aerodynamics. The 380 may have more air resistance, but it also has more powerful engines and a wing with more lift. All is scaled up in proportion.

Of course there were aerodynamic challenges, such as designing an appropriate wing to fit in the 80x80 box.


Another kind of engineering/physics: materials science, was probably a much bigger challenge than the aerodynamics. Scaling structural strength up to match size is tricky. As far as I know, weight increases faster than size if you scale up, so you have to find lighter materials.


And there are the infamous logistical challenges!
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jacobin777
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RE: Largest Obstacles To Overcome To Build The A380

Thu Apr 19, 2007 6:22 pm

Quoting Starlionblue (Reply 12):

Another kind of engineering/physics: materials science, was probably a much bigger challenge than the aerodynamics. Scaling structural strength up to match size is tricky. As far as I know, weight increases faster than size if you scale up, so you have to find lighter materials.

...had the A380 been designed now, it probably would have been a much more efficient aircraft-i.e.-probably more CFRP than it has and certainly next generation engines..

....that being said, it would have been financially impossible for Airbus to design/manufacture and build the A320NG, A350XWB and A380 at the same time.....


The A380 and B748 are probably the last two mostly-aluminum jets to be built.....
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astuteman
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RE: Largest Obstacles To Overcome To Build The A380

Fri Apr 20, 2007 12:38 am

Quoting A320ajm (Reply 11):
I think it would have been the physics. Is it possible to build such a big aircraft an lift it in the sky?

A320ajm - welcome to A-net. Hope you enjoy it. You'll learn lots, especially here on Tech-ops.

For what its worth, the A380 has been specifically designed with a very high lift wing.
The A380 is type certified at 569 tonnes (a 747-400 is around 400 tonnes)
The A380 wing has been designed to provide enough lift to give a 625 tonne version of the aircraft the same field, and climb performance as the 747.
(Whether a 625 tonne A380 version is ever built is a different matter).
But that is why the A380 wing is so incredibly large.
In fact, the wing area is so great, that the A380 wing loading (aircraft weight divided by wing area) is much lower than a 747.

The result of this is that the 569 tonne A380 actually has substantially better take-off and climb capability than the 747-400
It also has a lower landing speed  Smile

Quoting A320ajm (Reply 11):
For example, the A380 will have a larger air resistance than other aircraft

It's worth having a bit of care to differentiate between the air resistance and the lift.
One advantage that the huge 80m wingspan confers on the A380 is that it allows it to produce much more lift without a proportional increase in drag (resistance, as you put it).
That capability is a function of the wing span.

Quoting Starlionblue (Reply 12):
Of course there were aerodynamic challenges, such as designing an appropriate wing to fit in the 80x80 box.

Hence comments like this. Airbus would have liked the wing span to be even greater (about 82.5m to 83m I believe), but they promised Airport Authorities around the world that the A380 would fit in an 80m x 80m "box" (without a lid, presumably...  biggrin  )

Quoting A320ajm (Reply 11):
This would have also affected the maximum speed.

This tends to be governed (I understand) by the onset of supersonic shockwaves in the airflow over the aircraft at high speed. When this happens, the drag (resistance) rises dramatically.
That is the reason that the A380 has such a long "forehead" above the cockpit windows.
It gives the airflow much more time to accelerate over that great big body without going supersonic, hence much less drag (resistance) at high speed.

The two guys on A-net that coached me in aerodynamics are OldAeroGuy and Zeke
I'm just regurgitating what they told me  Smile

Regards
 
zenarcade
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RE: Largest Obstacles To Overcome To Build The A380

Fri Apr 20, 2007 1:37 pm

Amazing post Astuteman! I'm sure many of us have learned something from reading it.

"One advantage that the huge 80m wingspan confers on the A380 is that it allows it to produce much more lift without a proportional increase in drag (resistance, as you put it)."

Could you possibly explain this further?

Wouldn't any additional lateral wing structure and wing paneling along the span naturally cause drag?

[Edited 2007-04-20 06:39:06]
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astuteman
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RE: Largest Obstacles To Overcome To Build The A380

Fri Apr 20, 2007 7:15 pm

Quoting Zenarcade (Reply 15):
"One advantage that the huge 80m wingspan confers on the A380 is that it allows it to produce much more lift without a proportional increase in drag (resistance, as you put it)."

Could you possibly explain this further?

In reality, you're best talking to OldAeroGuy and Zeke - they're much more "expert" on the matter. Read this thread (on this forum a bit lower down the page...) and prepare to get you head blown apart...  biggrin 
A380 And 748i Drag Comparisons (by Astuteman Feb 23 2007 in Tech Ops)

Grossly oversimplified, total drag comprises of subsets, such as:-
lift drag,
wetted (surface) area drag,
and appendage drag.

The lift drag component is very sensitive to wingspan, and (I'm told) can be expressed as

aircraft weight/the span squared

In other words, if you double the wing span, you reduce the lift drag by a factor of 4!  thumbsup 

Quoting Zenarcade (Reply 15):
Wouldn't any additional lateral wing structure and wing paneling along the span naturally cause drag?

The downside is that the bigger wing is a) heavier, and b) has a bigger wetted area, hence, as you say, the wetted area drag increases.  thumbsdown 

All manufacturers will trade these two conflicts off to achieve the best optimum. (typically, the longer the range, the better a big wingspan optimises)

This is why gliders have huge long, thin wings. it minimises lift drag, and minimises wetted area drag at the same time.

Airbus have said the optimum wing-span for a 625 tonne A380 would have been 82.5m to 85m.
Unfortunately, they were constrained by the 80m "box" that they agreed with the airports.

At this point field performance comes in.
In order to guarantee the take-off and landing capability of the 625 tonne option, Airbus had to achieve a certain wing area in order to generate the lift.
Because the span was constrained, the depth of the wing (from leading edge to trailing edge) is greater than it would typically be (it has a low aspect ratio).
This gives NO advantage in terms of lift drag, but sadly ADDS wetted area drag, AND weight.

The 569 tonne A380 of today is thus saddled with an overly large, overly heavy wing, because Airbus wanted to have the capability to grow the plane to 625 tonnes one day.
Without this, I'm sure the current A380 would still have an 80m wingspan, but with a much "thinner" wing (from front to back), which would be lighter too.

Engineers have a great many variables to juggle when making their decisions, and almost every decision trades a desirable charachteristic against an undesirable one.

Hope that helps.

Regards
 
flipdewaf
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RE: Largest Obstacles To Overcome To Build The A380

Sat Apr 21, 2007 8:21 pm

Quoting Astuteman (Reply 14):
A380 would fit in an 80m x 80m "box" (without a lid, presumably... biggrin )

The box has an 80ft high lid doesnt it?

Fred
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astuteman
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RE: Largest Obstacles To Overcome To Build The A380

Sun Apr 22, 2007 3:54 am

Quoting Flipdewaf (Reply 17):
The box has an 80ft high lid doesnt it?

At least whilst stationary or taxiing..  biggrin 
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XT6Wagon
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RE: Largest Obstacles To Overcome To Build The A380

Tue Apr 24, 2007 3:00 pm

The retarded management was the biggest obstacle. Or the national politics if you want to play the "chicken or the egg" game.
 
Vorticity
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RE: Largest Obstacles To Overcome To Build The A380

Tue Apr 24, 2007 3:44 pm

Quoting CoolGuy (Thread starter):
What were some of the greatest challenges from an engineering standpoint to build the A380? I'm impressed that it was actually accomplished with a wingspan of only 80m (in order to fit into the 80x80m box). Anything else? I know it's an amazing piece of work from an engineering point of view, but why?

$$$

The biggest engineering challenge in commercial aviation is money. The airplane has to be efficient, afforadable and it has to meet a million other constraints that academia never thinks about. (Which is why there are not BWB commercial airliners flying)
Thermodynamics and english units don't mix...
 
zenarcade
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RE: Largest Obstacles To Overcome To Build The A380

Wed Apr 25, 2007 3:40 pm

Quoting Vorticity (Reply 20):
The biggest engineering challenge in commercial aviation is money.

Money would not be an engineering challenge. Instead it would be a cause for engineering.
If a plane falls on the tarmac and no one is there, does it make any sound? - Starlionblue
 
Ps76
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RE: Largest Obstacles To Overcome To Build The A380

Thu May 10, 2007 11:28 am

Hi,

I have also noticed often that the A380 wing also looks too big for the aircraft, but sometimes think it must have been like this becuase the double-deck fuselage is much heavier. However it does seem incredibly big so have wondered if it would fly 0.8M cruise with much more down trim than something like the A340 etc.?

I think making the structure would have been one of the hardest part. Would making a pressure vessel of such large internal volume/non-circular shape not be much harder than fuselages before? I have no real idea how the aluminium fueslage section is built but I'm guessing pieces are put in a frameworks for joining to make circular longitunally spaced ribs and joined with longitudinal long pieces to form the basic framework with skin also riveted on (is the skin not made tight to provide further strength too?). Have once visited the A380 public factory tour in St.Nazaire where there were fuselage sections and the massive volume/non-circle shape looked like it would be much harder to make rigid/strong to me (especially while making light?)

Finally I wonder with the length of the A380 not making it a little less naturally aerodynamically stable - maybe a little more "jittery" (though not unsafe) (I wonder similarly like with the A318). If the aircraft is pivoting about it's center of gravity wouldn't the short wing-tail length not be approaching the desired minimum level. I once saw a video with a GeeBee(?) in it - obviously it's not that extreme by any means but I'm guessing it wouldn't want to be too much shorter? (Although I don't understand why the less pivot length would mean a 'harder' natural stability except by feeling intuitively that it would).

P.
 
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Starlionblue
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RE: Largest Obstacles To Overcome To Build The A38

Thu May 10, 2007 9:03 pm

Quoting Ps76 (Reply 22):
Finally I wonder with the length of the A380 not making it a little less naturally aerodynamically stable - maybe a little more "jitter

Nah. There are other aircraft with such a proportionally short moment arm. For example the 318. No problem. Just larger empennage.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
rwessel
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RE: Largest Obstacles To Overcome To Build The A380

Fri May 11, 2007 1:46 pm

Quoting Starlionblue (Reply 23):
Nah. There are other aircraft with such a proportionally short moment arm. For example the 318. No problem. Just larger empennage.

The 747SP being another perfect example.
 
Ps76
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RE: Largest Obstacles To Overcome To Build The A380

Sat May 12, 2007 4:29 am

Quoting Starlionblue (Reply 23):

Quoting Ps76 (Reply 22):
Finally I wonder with the length of the A380 not making it a little less naturally aerodynamically stable - maybe a little more "jitter

Nah. There are other aircraft with such a proportionally short moment arm. For example the 318. No problem. Just larger empennage.

Quoting Rwessel (Reply 24):

Quoting Starlionblue (Reply 23):
Nah. There are other aircraft with such a proportionally short moment arm. For example the 318. No problem. Just larger empennage.

The 747SP being another perfect example.

Nice replies. Very polite/civilized (not)!

P.

[Edited 2007-05-11 21:31:43]
 
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Starlionblue
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RE: Largest Obstacles To Overcome To Build The A380

Sat May 12, 2007 5:09 am

Quoting Ps76 (Reply 25):
Nice replies. Very polite/civilized (not)!

???
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Ps76
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RE: Largest Obstacles To Overcome To Build The A380

Sat May 12, 2007 6:24 am

Quoting Starlionblue (Reply 26):

Quoting Ps76 (Reply 25):
Nice replies. Very polite/civilized (not)!

???

The replies basically sounded rude to me - more dismissive/arrogant than too much else. Whatever.

P.
 
Kukkudrill
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RE: Largest Obstacles To Overcome To Build The A380

Sat May 12, 2007 6:46 am

Quoting Ps76 (Reply 27):
The replies basically sounded rude to me - more dismissive/arrogant than too much else. Whatever.

What gives you that impression? I don't see any rudeness.
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Starlionblue
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RE: Largest Obstacles To Overcome To Build The A380

Sat May 12, 2007 9:45 pm

Quoting Ps76 (Reply 27):
The replies basically sounded rude to me - more dismissive/arrogant than too much else. Whatever.

It should be well known on the forums that I am not particularly prone to rudeness or condescension. I'm sorry if you got that impression. May I recommend you grow a thicker skin?

As a primer, let me provide this:
- Not rude. Trying to correct without being condescending: "Nah, not really"
- Rude and dismissive: "You are obviously a 14 year old using daddy's computer. You know nothing of aviation. I have forty years experience flying everything from the Wright Flyer to 747s (with a stint as Space Shuttle commander) and I can tell you that you are totally off the mark pal."
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
astuteman
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RE: Largest Obstacles To Overcome To Build The A380

Tue May 15, 2007 2:13 am

Quoting Ps76 (Reply 22):
I have also noticed often that the A380 wing also looks too big for the aircraft, but sometimes think it must have been like this becuase the double-deck fuselage is much heavier.

If you look further up the thread, you'll see a clear and concise (I hope  Wink ) explanation of EXACTLY why the A380 wing is the size it is. Reading the thread is most definitely to be recommended.  Smile

Quoting Ps76 (Reply 22):
Would making a pressure vessel of such large internal volume/non-circular shape not be much harder than fuselages before?

No, it would be no harder.

Quoting Ps76 (Reply 22):
Finally I wonder with the length of the A380 not making it a little less naturally aerodynamically stable - maybe a little more "jittery"

As Starlionblue so reasonably pointed out, the A380 has a humungous tail.
It's actually too large, as it's been designed to cope with a 625t A380, whereas the current one is only 569t.  Smile

(PS - If you can tolerate a bit of friendly advice, if you think Starlionblue's and Rwessel's responses were in the least bit rude, you're in the wrong forum. From my seat they were perfectly reasonable, pleasant, in fact, responses.
Go on Civil Aviation, and say you think the 787 (or A380) is a piece of Cr*p. You'll pretty soon get a reference point for unpleasant responses....  Smile )

Regards
 
prebennorholm
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RE: Largest Obstacles To Overcome To Build The A380

Wed May 16, 2007 4:19 am

Quoting Ps76 (Reply 22):
I think making the structure would have been one of the hardest part. Would making a pressure vessel of such large internal volume/non-circular shape not be much harder than fuselages before?

"Non-circular" ???

The A380 fuselage is indeed circular. But there are three circles. It is what is called a "triple bubble" design.

The upper fuselage above the the upper floor is circular, and stretch of the upper floor keeps it in shape when pressurized.

Same with the lower fuselage below the lower floor.

The diameter of the circular walls between the lower and upper floors is calculated so it keeps exactly the same circular shape whatever the cabin pressure difference may be.

In principle that is nothing new. Double bubble is almost the norm on airliners. DC-8, DC-9, MD-80, B-707, 717, 727, 737, 757 and many more, they are all double bubbles relying on stretch of the floor to keep it in shape.

The A380 has one more bubble than usual, but then it also has one more floor to keep it in shape.

The B747 is actually a lot more complicated since it up front has a double bubble which blends into a single bubble. Some day I would like so see how they did that stunt.
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WingedMigrator
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RE: Largest Obstacles To Overcome To Build The A380

Wed May 16, 2007 11:54 am

Quoting Prebennorholm (Reply 31):
The A380 fuselage is indeed circular. But there are three circles. It is what is called a "triple bubble" design.

The A380 fuselage has an ovoid cross section. The radius of curvature of the skin varies continuously. It is a "triple bubble" only in the sense that the floor beams are in tension from pressure loads.
 
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Starlionblue
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RE: Largest Obstacles To Overcome To Build The A380

Wed May 16, 2007 12:35 pm

Quoting Prebennorholm (Reply 31):

The B747 is actually a lot more complicated since it up front has a double bubble which blends into a single bubble. Some day I would like so see how they did that stunt.

With difficulty, seeing as the slab sides created such troubles when certifying.  Wink
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