Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Will We See Jet Donkeys Soon?  
User currently offlineLH707330 From United States of America, joined Jun 2012, 588 posts, RR: 0
Posted (1 year 7 months 1 week 5 days 22 hours ago) and read 5884 times:

I was reading this FG article and the picture of the aircraft taking off with the dolly caught my eye. The idea of propelling aircraft with a ground-based acceleration device is not new (aircraft carrier catapults), but what regulatory hurdles would need to be surmounted to enable this for commercial aircraft?

I see many benefits to jet donkey use, including reduced weight due to smaller engines, less flaps gear, shorter takeoff rolls, better climbout due to lower flap drag (smaller/no flaps), less jet noise, and the ability to use a rechargeable (with renewables) dolly to accelerate the aircraft. Downsides include infrastructure dependency (what if you divert to a field without them?). When I was in college I considered entering this as an Airbus fly your ideas challenge entry, but then figured that it seemed like such an obvious move that it would have been done already if there weren't a big log in the road. Thoughts?

22 replies: All unread, jump to last
 
User currently offlinerwessel From United States of America, joined Jan 2007, 2238 posts, RR: 2
Reply 1, posted (1 year 7 months 1 week 5 days 22 hours ago) and read 5849 times:
Support Airliners.net - become a First Class Member!

Quoting LH707330 (Thread starter):
Downsides include infrastructure dependency (what if you divert to a field without them?).

Emergency airfields could be equipped with an updated version of the USAF's HAVR Bounce or USN's Flexdeck systems (or perhaps the contemporary British system). Basically an arresting cable to stop the aircraft, and a bouncy mat for the now stopped aircraft to drop onto.   

Check out the article in:

http://www.public.navy.mil/airfor/centennial/Documents/vol3iss3.pdf


User currently offlineTWA772LR From United States of America, joined Nov 2011, 1137 posts, RR: 1
Reply 2, posted (1 year 7 months 1 week 5 days 21 hours ago) and read 5821 times:

They do have arresting cables for military fighter planes, like the Israeli F15 that lost the wing and landed used an arresting cable. I guess it could be possible to launch a 747 or A380 with a catapult-like system, just the ammount of power and force behind it would be immense.


Я говорю по-русский. :)
User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2033 posts, RR: 13
Reply 3, posted (1 year 7 months 1 week 5 days 18 hours ago) and read 5748 times:

Hm, why not use the landscape - and build downhill sloped runways for take-off, like the one at CVF?


I've seen that in a magazine, back in the late 1980ies... I wonder how the V1 and required runway length calculations will be, though.



David



Keeping calm is terrorism against those who want to live in fear.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 4, posted (1 year 7 months 1 week 5 days 16 hours ago) and read 5697 times:

Quoting flyingturtle (Reply 3):

Hm, why not use the landscape - and build downhill sloped runways for take-off, like the one at CVF?


I've seen that in a magazine, back in the late 1980ies... I wonder how the V1 and required runway length calculations will be, though.

There was a post years ago about this I think. The Dash 7 is at V1 when it releases the brakes. 



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 5, posted (1 year 7 months 1 week 5 days 11 hours ago) and read 5579 times:

Quoting LH707330 (Thread starter):
what regulatory hurdles would need to be surmounted to enable this for commercial aircraft?

The "hurdle" is that no regulations exist right now; such a system would require a total re-write of the takeoff requirements regulations because the existing regulations just wouldn't work. The last time a regulatory re-write of that magnitude was required was probably the invention of the jet engine.

You also need to figure out a way to deal with single-engine go-around, where you can't get any help from the ground.

Tom.


User currently offlineHAWK21M From India, joined Jan 2001, 31568 posts, RR: 57
Reply 6, posted (1 year 7 months 1 week 5 days 7 hours ago) and read 5464 times:

Quoting LH707330 (Thread starter):
jet donkey

Whats the history on this term usage.



Think of the brighter side!
User currently offlinevikkyvik From United States of America, joined Jul 2003, 9391 posts, RR: 27
Reply 7, posted (1 year 7 months 1 week 5 days 6 hours ago) and read 5445 times:
Support Airliners.net - become a First Class Member!

Quoting flyingturtle (Reply 3):
Hm, why not use the landscape - and build downhill sloped runways for take-off, like the one at CVF?

Some airports are exceptions due to terrain, like CVF, but in general, what do you do when the wind switches directions?



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2033 posts, RR: 13
Reply 8, posted (1 year 7 months 1 week 5 days 2 hours ago) and read 5355 times:

Quoting vikkyvik (Reply 7):
Some airports are exceptions due to terrain, like CVF, but in general, what do you do when the wind switches directions?

Hoist sails and call it a sailplane.   


David



Keeping calm is terrorism against those who want to live in fear.
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 25
Reply 9, posted (1 year 7 months 1 week 5 days 1 hour ago) and read 5331 times:

Quoting LH707330 (Thread starter):
The idea of propelling aircraft with a ground-based acceleration device is not new (aircraft carrier catapults), but what regulatory hurdles would need to be surmounted to enable this for commercial aircraft?

You couldn't do it with today's commercial airframes. The structure is not built for this kind of abuse. You'll rip that nose gear off like a toothpick!

Even if the technology was applied to commercial aircraft, it would be a very expensive venture. The costs outweigh the benefits. IMO, I don't ever see this coming.



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineLH707330 From United States of America, joined Jun 2012, 588 posts, RR: 0
Reply 10, posted (1 year 7 months 1 week 4 days 21 hours ago) and read 5234 times:

Quoting HAWK21M (Reply 6):
Whats the history on this term usage.

Not precisely sure, but I think the USAF thought of it back in the 1950s sometime when they were looking at ways to get a/c off the ground from short strips.

Quoting AirframeAS (Reply 9):
You couldn't do it with today's commercial airframes. The structure is not built for this kind of abuse. You'll rip that nose gear off like a toothpick!

I was thinking you attach it to the mains and have a sort of backstay from the gear legs aft.


User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 25
Reply 11, posted (1 year 7 months 1 week 4 days 14 hours ago) and read 5136 times:

Quoting LH707330 (Reply 10):
I was thinking you attach it to the mains and have a sort of backstay from the gear legs aft.

With some aircraft, like the 738 and 739 which are tail heavy, that's not going to work.



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlinewingscrubber From UK - England, joined Sep 2001, 845 posts, RR: 0
Reply 12, posted (1 year 7 months 1 week 4 days 7 hours ago) and read 5078 times:

I don't think the term 'jet donkey' will catch on! How about 'runway shuttle', or 'aircraft acceleration carraige' ?  
I think usage of something along the lines of aircraft carrier-style catapults, winches or carriages (the wright brothers used this method) is overdue for modern airliners. The obvious benefits are noise reduction, increased take-off performance and increased fuel efficiency - but it's a cost prohibitive concept.

Here's another idea; what about a Maglev runway? That could drastically improve take-off efficiency if an air vehicle could be accelerated up to a safe climb speed and then released, and in addition if that same aircraft could land on a Maglev runway too then it would need no landing gear or brakes, which could result in a much lighter aircraft.  

But - I severely doubt it'll ever happen, even though there's the old adage, a mile of road will take you one mile, a mile of runway will take you anywhere, the seem could apply to a mile of maglev runway  



Resident TechOps Troll
User currently offlinebhill From United States of America, joined Sep 2001, 924 posts, RR: 0
Reply 13, posted (1 year 7 months 1 week 4 days 7 hours ago) and read 5074 times:

Conveyor belts anyone?.................................


Carpe Pices
User currently offlineFabo From Slovakia, joined Aug 2005, 1211 posts, RR: 1
Reply 14, posted (1 year 7 months 1 week 4 days 2 hours ago) and read 5010 times:

Quoting flyingturtle (Reply 3):
Hm, why not use the landscape - and build downhill sloped runways for take-off, like the one at CVF?
Quoting flyingturtle (Reply 3):
I wonder how the V1 and required runway length calculations will be, though.

I cant help, but post a meme:



(ASDR stands for Accelerate-Stop Distance Required, and stands for the distance that the aircraft need to accelerate to V1 and stop again, obviously must be less than runway available)

Anyway regarding smaller engines, the aircraft would still have to be able to drag itself into climb on MTOW with one engine out, so I am not sure that would be feasible,
less/simpler flaps, I am afraid you still have to land... but it might be possible to get away with less flaps actually used for T/O,
all in all too small a benefit to be viable IMHO.



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlineLH707330 From United States of America, joined Jun 2012, 588 posts, RR: 0
Reply 15, posted (1 year 7 months 1 week 4 days ago) and read 4978 times:

Quoting Fabo (Reply 14):
less/simpler flaps, I am afraid you still have to land...

Couldn't you use a massive spoiler mounted directly over the gear leg that goes all the way back to the trailing edge to plant the gear and enable more aggressive braking? On a long haul a/c this might make more sense because your landing weight is a lot lower so you can lower your approach speed.


User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2033 posts, RR: 13
Reply 16, posted (1 year 7 months 1 week 3 days 17 hours ago) and read 4928 times:

Quoting Fabo (Reply 14):

Thank you, I've had a good laugh. 

I can't find that drawing that apeared in the 1980ies popular science magazine "P.M.", but it was even more dangerous - it was really a ski jump, and the airport was on top of a 30-story building. With a downward-sloped runway at least, you could offer a generous overrun area...



David



Keeping calm is terrorism against those who want to live in fear.
User currently offlineHAWK21M From India, joined Jan 2001, 31568 posts, RR: 57
Reply 17, posted (1 year 7 months 1 week 3 days 15 hours ago) and read 4921 times:

Quoting bhill (Reply 13):
Conveyor belts anyone?........

sure remember that debate...went on for a long time....



Think of the brighter side!
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 25
Reply 18, posted (1 year 7 months 1 week 3 days 13 hours ago) and read 4903 times:

Quoting HAWK21M (Reply 17):

Quoting bhill (Reply 13):
Conveyor belts anyone?........

sure remember that debate...went on for a long time....


With record replies and views! Good old days!



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlinePihero From France, joined Jan 2005, 4136 posts, RR: 76
Reply 19, posted (1 year 7 months 1 week 3 days 8 hours ago) and read 4835 times:
Support Airliners.net - become a First Class Member!

As usual, many things have been invented already. Just need to come out with improvred design.
The Baroudeur was designed some sixty years ago.
Have a look at this

But trhere probably is a simpler solution : electric motors bto the main gears.



Contrail designer
User currently offlineLH707330 From United States of America, joined Jun 2012, 588 posts, RR: 0
Reply 20, posted (1 year 7 months 1 week 1 day 9 hours ago) and read 4589 times:

Quoting Pihero (Reply 19):
The Baroudeur was designed some sixty years ago.

Which in turn took that idea from the Me-163 Komet, but I digress.

Quoting Pihero (Reply 19):
But trhere probably is a simpler solution : electric motors bto the main gears.

I'd imagine you'd have wheelspin issues with current aircraft tires....


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3423 posts, RR: 67
Reply 21, posted (1 year 7 months 3 days 12 hours ago) and read 3964 times:

Quoting HAWK21M (Reply 6):
Whats the history on this term usage.

The donkey part goes back to railroading where "helper" engines were kept at hilly portions of a route to assist in getting a train over the hills. The "helpers" were referred to as "donkeys".



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineLH707330 From United States of America, joined Jun 2012, 588 posts, RR: 0
Reply 22, posted (1 year 7 months 1 day 8 hours ago) and read 3766 times:

Here's another reference, this time referred to as "tractors." Looks like they may seem serious about finding a way to solve this issue.

http://www.flightglobal.com/news/art...ails-are-all-in-the-future-376312/


Top Of Page
Forum Index

Reply To This Topic Will We See Jet Donkeys Soon?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Will We See A Negatively Stable Airliner? posted Wed Apr 13 2005 21:41:51 by Lemmy
Changes We Will Ever See A 747-8F/I(ER)? posted Mon Jan 3 2011 14:46:08 by 747400sp
Truthfully, Will We Ever See A SST Again? posted Sat Aug 1 2009 20:59:45 by 747400sp
Will We Ever See Winglets On The Stabiliser posted Sun Feb 10 2008 12:56:18 by NEMA
Will We See An Twin Enigine A/C Powered By TP400 posted Tue May 3 2011 14:59:19 by 747400sp
Will Ever See A TU 254? posted Sat Jan 17 2009 10:27:26 by 747400sp
Engine Technology - Do We See A Revolution? posted Wed Dec 14 2005 19:28:26 by TheSonntag
Why Don't We See "Secondary Inlet Doors" Anymore? posted Sun May 9 2004 14:52:12 by YS11
The Year We Will See The End Of Tri Holers? posted Wed Jan 18 2012 18:50:15 by c5load
Will A Prop Ever Be Able To Go As Fast As A Jet? posted Fri Jul 23 2010 15:05:08 by c5load

Sponsor Message:
Printer friendly format