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Ground Power Augmentation  
User currently offline3arrows From Slovakia, joined Nov 2008, 5 posts, RR: 0
Posted (5 years 9 months 1 week 2 days 8 hours ago) and read 2416 times:

Hi guys! I make one bachelor project about ground power augmentation (GPA). For more closely explain, it is same ground device, which can help aircraft with take-off from runway. So GPA generate kind of energy, which is afford to aircraft in time of take-off from runway. For realization this devices (GPA) can by ramp, electromagnetic forces (electromagnetic rail), or catapult. Advantages of GPA could by reduction of consumption fuel, annoying sound around airport and reduction of emission. So what You think about GPA? Can by GPA realized in operation? Thank you for your opinions.

9 replies: All unread, jump to last
 
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 1, posted (5 years 9 months 1 week 2 days 5 hours ago) and read 2385 times:

Considering the weight of todays commercial aircraft,the advantages would never be present.
Practically it would never work out.also what would be reliability & back up of the system correctly functioning.

Personally I can only think of small aircraft or UAVs.

regds
MEL



Think of the brighter side!
User currently offlineWPIAeroGuy From United States of America, joined Aug 2007, 240 posts, RR: 0
Reply 2, posted (5 years 9 months 1 week 2 days 4 hours ago) and read 2365 times:



Quoting 3arrows (Thread starter):
reduction of consumption fuel

This has been brought up before, and its a common misconception that some sort of ground catapult will save fuel. Before any sort of launch the engines will have to be at takeoff thrust anyway, you're not saving fuel just because the engines aren't technically launching the aircraft.
The only reason I can see for a GPA is where runway space is very limited (as an aircraft carrier).

If the runway is shorter then that could make it easier to get around noise restrictions, but it won't mean that the engines are at less thrust, thus producing less noise.



-WPIAeroGuy
User currently offlinePGNCS From United States of America, joined Apr 2007, 2821 posts, RR: 45
Reply 3, posted (5 years 9 months 1 week 2 days 3 hours ago) and read 2356 times:



Quoting WPIAeroGuy (Reply 2):
Quoting 3arrows (Thread starter):
reduction of consumption fuel

This has been brought up before, and its a common misconception that some sort of ground catapult will save fuel. Before any sort of launch the engines will have to be at takeoff thrust anyway, you're not saving fuel just because the engines aren't technically launching the aircraft.
The only reason I can see for a GPA is where runway space is very limited (as an aircraft carrier).

If the runway is shorter then that could make it easier to get around noise restrictions, but it won't mean that the engines are at less thrust, thus producing less noise.

Agreed. Not to mention that the aircraft would have to be made immensely heavier to withstand the stresses involved, which would more than offset any potential savings. You also are unlikely to find many passengers willing or eager to endure the G-loads that would ensue.


User currently offline3arrows From Slovakia, joined Nov 2008, 5 posts, RR: 0
Reply 4, posted (5 years 9 months 1 week 4 hours ago) and read 2192 times:

what about passengers a G force. So the name of title it isn´t so good, becouse this device shouldn´t speed up the aircraft just as on aircraft carrier, but this device should by only compensation of the part of energy, wich is necessery to take-off from runway. It means, the passenger can feel the same G-force, wich is on normal take-off (in civil aircraft)

User currently offlineSB From United Kingdom, joined Aug 2006, 216 posts, RR: 0
Reply 5, posted (5 years 9 months 1 week 4 hours ago) and read 2182 times:

So essentially you nudge the aircraft into the air allowing a take-off with, for example, climb power set rather than take-off power? An interesting idea but I don't see it saving much fuel - the engines will still be running - and we already routinely use derated power (sometimes very close to climb thrust itself) for take-off to prolong engine life.

S.



"Confirm leave the hold and maintain 320kts?!"
User currently offlineWPIAeroGuy From United States of America, joined Aug 2007, 240 posts, RR: 0
Reply 6, posted (5 years 9 months 1 week 3 hours ago) and read 2176 times:



Quoting SB (Reply 5):
So essentially you nudge the aircraft into the air allowing a take-off with, for example, climb power set rather than take-off power? An interesting idea but I don't see it saving much fuel - the engines will still be running - and we already routinely use derated power (sometimes very close to climb thrust itself) for take-off to prolong engine life.

S.

If you're going to be at climb thrust at liftoff, wouldn't you also have to be at climb speed? In that case you'd have to increase runway length, which would most likely negate any benefits whatsoever.

Catapults and other systems have their purpose, its just not to save fuel. Maybe future engines will have reliability high enough so that there could be a powered launch under minimum thrust until a certain altitude at which point the thrust would increase, but I don't see it as being likely.



-WPIAeroGuy
User currently offlineSB From United Kingdom, joined Aug 2006, 216 posts, RR: 0
Reply 7, posted (5 years 9 months 1 week 1 hour ago) and read 2146 times:

No, thrust required is a function of weight, acceleration and vertical gradient. The airspeed (V2) is also a function of weight, but isn't related to the thrust available. The take-off run would indeed be much longer due to reduced thrust, but that's where the nudge could come in.

Generally thrust reduction altitude is lower than acceleration altitude.

S.



"Confirm leave the hold and maintain 320kts?!"
User currently offlineBond007 From United States of America, joined Mar 2005, 5408 posts, RR: 8
Reply 8, posted (5 years 9 months 1 week 1 hour ago) and read 2141 times:

Presumably there is a conveyor belt somewhere in this scenario?


Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlinePGNCS From United States of America, joined Apr 2007, 2821 posts, RR: 45
Reply 9, posted (5 years 9 months 1 week 1 hour ago) and read 2139 times:



Quoting Bond007 (Reply 8):
Presumably there is a conveyor belt somewhere in this scenario?

Jimbo...man, you beat me to it!  Smile


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