19 replies to this topic

[planogram]

Crazy test pilot Tex Johnson does a barrel roll in the pioneering Boeing 707. Makes me wonder what modern commercial planes are truly capable of in terms of performance and maneuverability if pushed to the limits.

[AlexVandross]

There are air shows were 747s do this kind of maneuvering.

[planogram]

AlexVandross, on 07 February 2013 - 03:34 AM, said:

There are air shows were 747s do this kind of maneuvering.

That would be interesting to see, do you have a video link or pics?

[Crag_r]

Its only a 1 G maneuver (what you experience living at sea level on Earth all the time), I can technically do the same thing in my 172

[planogram]

Crag_r, on 07 February 2013 - 06:31 AM, said:

Its only a 1 G maneuver (what you experience living at sea level on Earth all the time), I can technically do the same thing in my 172

In theory, however the 172 has a gravity fed fuel system. I wouldn't try it.

[bearrick]

That was a prototype.  Sometimes those have mostly stripped interiors when being taken around to sell to prospective buyers.  Plus no passengers or cargo.  And I know they do the vomit comet... maybe they could take thrill seekers up and do stuff like that in addition to the weightless dives.

I'd love it.

[lapon2046]

Some 747's have pulled several G's and possibly broken Mach 1: http://en.wikipedia....ines_Flight_006
They landed OK, but the elevators were shot.

[Lieutenant_Bob264]

it invariably seems that anyone discussing "high g" maneuvers in any form of media uses an aileron roll as the generic clip, annoys me every time, lol.

[Crag_r]

planogram, on 07 February 2013 - 11:42 AM, said:

In theory, however the 172 has a gravity fed fuel system. I wouldn't try it.

Well i have enough fuel in the engine fuel reservoir for the maneuver, and its fuel injected not a carbie, i can use the aux fuel pump if i have to.

[SkyWolf__WM]

Wings would quite quickly fall off.

[gaidalcain85]

MacMyers, on 07 February 2013 - 10:54 PM, said:

Wings would quite quickly fall off.

Why would you say that? In fact the wings would not fall off, planes are built a little tougher than that  

[CrashTailspin]

*puts flight instructor / airline pilot hat on*

AlexVandross, on 07 February 2013 - 03:34 AM, said:

There are air shows were 747s do this kind of maneuvering.

To my knowledge, a 747 has never been barrel rolled at an airshow.  There was a crazy B-52 pilot at Fairchild AFB a while back who thought his B-52 was an F-16.  He thought this so much so that he decided to prove it.....until he augered into the ground from an unrecoverable high-bank turn.

Crag_r, on 07 February 2013 - 06:31 AM, said:

Its only a 1 G maneuver (what you experience living at sea level on Earth all the time), I can technically do the same thing in my 172

This is true.  A properly executed barrel roll is a continuous 1-G maneuver, since you're continuously applying back pressure throughout the maneuver.

planogram, on 07 February 2013 - 11:42 AM, said:

In theory, however the 172 has a gravity fed fuel system. I wouldn't try it.

Regardless if it had a gravity fed system or required a fuel pump, so long as positive Gs were applied to the aircraft, fuel will still feed to the engine.  The issue comes when you start applying negative Gs to an aircraft that is not fuel-injected.  

A perfect example of this is early-Mk. Spitfires vs. Messerschmitt Bf.109s during the Battle of Britain.  Bf.109s were fuel-injected, while Spitfires were not.  When being pursued by a Spitfire, a 109 pilot would simply push the stick forward and enter a steep dive.  If the Spit pilot did this, they would un-port the fuel and potentially cause their engine to seize.  To alleviate this, the Spit pilot could roll inverted and pull on the stick, causing positive Gs and allowing them to continue the pursuit.

MacMyers, on 07 February 2013 - 10:54 PM, said:

Wings would quite quickly fall off.

A 1-G maneuver causes no significant additional stress to the aircraft.  What you're thinking of is a term called Load Factor.  Load factor is the total amount of lift the aircraft is producing divided by the aircraft's weight, which is expressed in the term "Gs".



In level flight, an aircraft's total lift equals its weight.  However, when an aircraft enters a level turn, its vertical component of lift now equals its weight.  In order to create enough vertical lift to equal its weight, the aircraft has to create more total lift.  This total lift (and equal but opposite "resultant force") now gets divided by the aircraft's weight, which results in the aircraft's Load Factor.

Any time an aircraft produces more total lift than the aircraft's weight, it experiences a Load Factor of more than 1.  For example, a level 60 degree bank turn equals 2Gs.  A 70 degree bank turn is 3Gs.  Keep in mind, however, that lift is always relative to the aircraft's flight path, and not necessarily in which direction the nose is pointed.  But I digress...

Suffice to say that a discussion on Load Factor is best done in a classroom (with a lot of markerboards and multiple colored markers).  A forum?  Not the greatest locale.

[SkyWolf__WM]

gaidalcain85, on 08 February 2013 - 01:58 AM, said:

Why would you say that? In fact the wings would not fall off, planes are built a little tougher than that  

Heh... OK trying flying one upside down for awhile. I'm not talking about a G controlled roll.

[Sgt_Goldham]

MacMyers, on 08 February 2013 - 06:08 AM, said:

Heh... OK trying flying one upside down for awhile. I'm not talking about a G controlled roll.

Flying inverted does not produce any more g's than normal.

[stealth250]

CrashTailspin, on 08 February 2013 - 03:03 AM, said:

*puts flight instructor / airline pilot hat on*



To my knowledge, a 747 has never been barrel rolled at an airshow.  There was a crazy B-52 pilot at Fairchild AFB a while back who thought his B-52 was an F-16.  He thought this so much so that he decided to prove it.....until he augered into the ground from an unrecoverable high-bank turn.



This is true.  A properly executed barrel roll is a continuous 1-G maneuver, since you're continuously applying back pressure throughout the maneuver.



Regardless if it had a gravity fed system or required a fuel pump, so long as positive Gs were applied to the aircraft, fuel will still feed to the engine.  The issue comes when you start applying negative Gs to an aircraft that is not fuel-injected.  

A perfect example of this is early-Mk. Spitfires vs. Messerschmitt Bf.109s during the Battle of Britain.  Bf.109s were fuel-injected, while Spitfires were not.  When being pursued by a Spitfire, a 109 pilot would simply push the stick forward and enter a steep dive.  If the Spit pilot did this, they would un-port the fuel and potentially cause their engine to seize.  To alleviate this, the Spit pilot could roll inverted and pull on the stick, causing positive Gs and allowing them to continue the pursuit.



A 1-G maneuver causes no significant additional stress to the aircraft.  What you're thinking of is a term called Load Factor.  Load factor is the total amount of lift the aircraft is producing divided by the aircraft's weight, which is expressed in the term "Gs".



In level flight, an aircraft's total lift equals its weight.  However, when an aircraft enters a level turn, its vertical component of lift now equals its weight.  In order to create enough vertical lift to equal its weight, the aircraft has to create more total lift.  This total lift (and equal but opposite "resultant force") now gets divided by the aircraft's weight, which results in the aircraft's Load Factor.

Any time an aircraft produces more total lift than the aircraft's weight, it experiences a Load Factor of more than 1.  For example, a level 60 degree bank turn equals 2Gs.  A 70 degree bank turn is 3Gs.  Keep in mind, however, that lift is always relative to the aircraft's flight path, and not necessarily in which direction the nose is pointed.  But I digress...

Suffice to say that a discussion on Load Factor is best done in a classroom (with a lot of markerboards and multiple colored markers).  A forum?  Not the greatest locale.

????.anyway what kind of plane do you pilot?

[SkyWolf__WM]

Sgt_Goldham, on 18 February 2013 - 07:50 PM, said:

Flying inverted does not produce any more g's than normal.

Heheh... yeah... but the aircraft is not designed to take said G's on the top of the control surfaces. If you try to fly most aircraft inverted the wings will come off. Quite rapidly in fact.

Try it it if you don't believe me.

[stealth250]

MacMyers, on 18 February 2013 - 08:25 PM, said:

Heheh... yeah... but the aircraft is not designed to take said G's on the top of the control surfaces. If you try to fly most aircraft inverted the wings will come off. Quite rapidly in fact.

Try it it if you don't believe me.

can I borrow our Boeing 707?

[Old_Crow51]

MacMyers, on 18 February 2013 - 08:25 PM, said:

Heheh... yeah... but the aircraft is not designed to take said G's on the top of the control surfaces. If you try to fly most aircraft inverted the wings will come off. Quite rapidly in fact.

Try it it if you don't believe me.

My god!

You put the same load on the wings flying inverted as you do flying level, the only difference is because the airfoil is upside down the aircraft is going to want to pull down as opposed to up (most aircraft). The Extra 300's wings are designed with zero incidence, so it will fly equally as good upside down as it would right side up.

Basically what Crash said is completely correct, as he is a pilot, and I as well am a pilot. We have to learn this stuff from day one.

[Crag_r]

MacMyers, on 18 February 2013 - 08:25 PM, said:

Heheh... yeah... but the aircraft is not designed to take said G's on the top of the control surfaces. If you try to fly most aircraft inverted the wings will come off. Quite rapidly in fact.

Try it it if you don't believe me.

You only have -1G while flying inverted in Level flight, legally in order for an Aircraft to be Airworthy (for the most part) it has to be able to easily cope with that.

So no the wings will not fall off, remember wings are VERY strong things they take the entire weight of the Aircraft in the Air.

[SkyWolf__WM]

Heh... this is a pretty funny topic.

I guess it depends on your definition of "flying inverted"