GolfOscarDelta From India, joined Feb 2008, 170 posts, RR: 0 Posted (7 years 9 months 3 weeks 3 days 18 hours ago) and read 6587 times:
Can retired aircraft be modified to be used as ground effect aircraft?
Assuming that a majority of the airliners are retired mainly due to the toll on their fuselages from repeated pressurization-depressurization cycles; can these aircraft still be used if they don’t have to undergo pressurization cycles, i.e. can they be used if they are required to fly only a few feet off the ground thus avoiding the pressurization issues?
Next question: is it possible to modify a MD-8X(DC-9X) or a 727 or any other rear engined airliner to take pontoons instead of landing gears? (Assuming that suitable pontoons are designed and suitable structural reinforcements can be made)
If the answer to my above two questions is yes, can such a modified aircraft be used as a wing in ground effect aircraft?
My ultimate point is, a lot of MD-8X’s will be retired in the next few years and so will most of the remaining 727’s. So if such a modification as described above is possible and my initial assumption (regarding retirement of airliners) is right, then can these modified aircraft be used as inter-island/port to port/coast to coast, ground effect aircraft/ferries? Potentially replacing watercraft.
Would they be attractive enough in terms of cost?
Will they have a CASM comparable to ferries? Considering that the modified aircraft has been bought for a fraction of its original price since it has paid for itself and going to be retired
The challenges involved (that I can think of):
1. Modifying the aircraft to take on pontoons instead of landing gear
2. Corrosion on engine parts and other aircraft parts due to salt water
3. Wings are optimized to be most efficient at higher speeds, hence lower efficiencies (if the wing can be replaced with a purpose designed wing then even better)
1. An aircraft with pontoons will probably have its max speed limited to a speed even lower than the gear down velocity (faster than a watercraft but still not fast enough)
2. Navigation w.r.t water based traffic viz. other watercraft
3. Passenger boarding, baggage handling, fueling, misc. airport related operation issues.
4. Noise both inside aircraft and to the surroundings, due to jet engines being so close to the ground
Given this much:
Now is all this possible?
If it is possible what other challenges (technical/operational/other) could be faced in implementing such an idea?
Also another question at this juncture, why haven’t WiG aircraft caught on commercially? Are any technological breakthroughs or technologies required to make them an operational reality?
Avioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 1, posted (7 years 9 months 3 weeks 3 days 17 hours ago) and read 6562 times:
I think you'll find that the reason for retirement of the aircraft you mention is more on the lines of economics dictated by the engines rather than airframe fatigue.
There's plenty of life left in the MD80 series fleet but the engines burn too much fuel when compared to the next generation aircraft and the upcoming noise and carbon emission standards won't be easy to meet for any reasonable cost.
I also think you'll find the stresses on an aircraft in ground effect are not minor by any measure and the Boeing aircraft, in particular, will be hard put to meet the demands. Plus the engines on the 727's would have to be upgraded again at prohibitive cost to make them feasable at all.
Just one old gray hair's opinion mind you. . .
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
HAWK21M From India, joined Jan 2001, 31821 posts, RR: 55
Reply 2, posted (7 years 9 months 3 weeks 3 days 9 hours ago) and read 6507 times:
Its always economics that grounds an Aircraft permanently most of the time.
the checks due to keep the Aircraft airworthy is not worth the expenses hence its works out better to sell the Aircraft or scrap it.
Any Aircraft wanting to fly will need to be Airworthy on paper too.
Dw747400 From United States of America, joined Aug 2001, 1274 posts, RR: 1
Reply 3, posted (7 years 9 months 2 weeks 5 days 20 hours ago) and read 6306 times:
Keep in mind aircraft are optimized for the flight levels as well. A B737, for example, burns twice as much fuel going from BWI to CLT at 2000 feet (I don't know about terrain, this is just theoretical) as it does at FL400. The L/D benefit of staying in ground effect might help some, but I doubt it can make up for those numbers.
MX757 From United States of America, joined Aug 2005, 628 posts, RR: 11
Reply 5, posted (7 years 9 months 2 weeks 5 days 14 hours ago) and read 6258 times:
Quoting GolfOscarDelta (Thread starter): Next question: is it possible to modify a MD-8X(DC-9X) or a 727 or any other rear engined airliner to take pontoons instead of landing gears? (Assuming that suitable pontoons are designed and suitable structural reinforcements can be made)
Probably not. If pontoons were installed on the nose and main landing gear the resulting rooster tail from take off and landing would more than likely go directly into the engine inlets causing flame-out. This is an inherent problem with tail mounted engines. I have spent many times in the inlets of DC-9/MD-80s and 727s repairing or changing fan blades (disk change) due FOD being thrown into engines from the main gear tires.
Then again anything is possible if somebody wants to spend the money.