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KC-135 Required Runway Length  
User currently offlinetsra From United States of America, joined Feb 2007, 208 posts, RR: 0
Posted (9 months 4 weeks 23 hours ago) and read 5992 times:

I was wondering if anyone knows what the takeoff/landing requirements for the KC-135 are on a typical training or air show (if that ever happens again) sortie. I think I may of heard 7,000 feet and a shorter amount if permission was granted but was not sure. Do we know the performance difference between a KC-135 and KC-46 yet?

20 replies: All unread, jump to last
 
User currently offlinerc135x From , joined Dec 1969, posts, RR:
Reply 1, posted (9 months 4 weeks 23 hours ago) and read 5988 times:

7000 feet x 147 feet.

See Section 5, page 48.

http://www.vusaf.org/amwtc/97amw/55%...light%20Guide-%2021%20Aug%2004.pdf

Obviously there are possible variations under special conditions (Cherokee Rose, for example), but these are the operational limits.


User currently offlinebigbird From United States of America, joined Aug 2004, 179 posts, RR: 0
Reply 2, posted (9 months 4 weeks 16 hours ago) and read 5882 times:
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I realize that this was a long time ago but when I was stationed at Robins AFB back in the mid-1960s our KC-135A s would use between 11000 and 12000 on T/O. It was closer to the latter on hot days. Sometimes they would return after their missions and still have some pine needles in the intakes from the tops of trees at the end of the runway. Of course these were fully loaded airplanes. If anyone here ever witnessed a fully loaded "water wagon" they were truly something to behold.


bigbird from georgia
User currently offlineKC135Hydraulics From United States of America, joined Nov 2012, 270 posts, RR: 0
Reply 3, posted (9 months 4 weeks 11 hours ago) and read 5804 times:

Quoting bigbird (Reply 2):
Quoting bigbird (Reply 2):
I realize that this was a long time ago but when I was stationed at Robins AFB back in the mid-1960s our KC-135A s would use between 11000 and 12000 on T/O. It was closer to the latter on hot days. Sometimes they would return after their missions and still have some pine needles in the intakes from the tops of trees at the end of the runway. Of course these were fully loaded airplanes. If anyone here ever witnessed a fully loaded "water wagon" they were truly something to behold.

The R-models have decidedly better takeoff performance as you may expect.


User currently onlinemoose135 From United States of America, joined Oct 2004, 2245 posts, RR: 11
Reply 4, posted (9 months 3 weeks 6 days 22 hours ago) and read 5711 times:

Quoting bigbird (Reply 2):
If anyone here ever witnessed a fully loaded "water wagon" they were truly something to behold.

Took off out of Pease, dragging some F-4s to Europe. 285K gross weight, with water, we used better than 10,000 feet of runway to get airborne. Never got to fly an R-model, but from what I've seen, they are much better performers. Of course, kids flying them these days will never experience the sound and fury of a wet takeoff...

We were Gods - we made water burn!



KC-135 - Passing gas and taking names!
User currently offlinebigbird From United States of America, joined Aug 2004, 179 posts, RR: 0
Reply 5, posted (9 months 3 weeks 6 days 16 hours ago) and read 5649 times:
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You had to keep water warm also. When the temperature dropped below a certain point we had to run the MD-3 power units to keep the water on the "alert birds". Also in real cold climates, i.e. Goose Bay, where I was stationed I believe the water was drained. Is this correct? I am not sure as it was a long time ago. I was stationed there in 1965-66.


bigbird from georgia
User currently offlinerc135x From , joined Dec 1969, posts, RR:
Reply 6, posted (9 months 3 weeks 6 days 15 hours ago) and read 5634 times:

Quoting bigbird (Reply 5):
When the temperature dropped below a certain point we had to run the MD-3 power units to keep the water on the "alert birds". Also in real cold climates, i.e. Goose Bay, where I was stationed I believe the water was drained. Is this correct? I am not sure as it was a long time ago.

You are indeed correct. As it has been an equally long time, I don't recall the temperature when heat was applied or when the water was drained.

Alert was always hard on the airplanes: heating water, tire rotation, maintenance necessitated by weekly "horns." It was just as hard on the crew chiefs who huddled in alert trucks in the freezing weather.


User currently onlinemoose135 From United States of America, joined Oct 2004, 2245 posts, RR: 11
Reply 7, posted (9 months 3 weeks 6 days 14 hours ago) and read 5615 times:

Quoting rc135x (Reply 6):
I don't recall the temperature when heat was applied or when the water was drained.

Outside air temp below 40F required heaters, OAT below 20F and we dumped the water. Amazing the stuff that you find rattling around your head...

Quoting rc135x (Reply 6):
It was just as hard on the crew chiefs who huddled in alert trucks in the freezing weather.

Ain't that the truth! Always felt for those guys.



KC-135 - Passing gas and taking names!
User currently offlinebigbird From United States of America, joined Aug 2004, 179 posts, RR: 0
Reply 8, posted (9 months 3 weeks 5 days 16 hours ago) and read 5433 times:
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I was one of the APs that was out there along with them. I can really relate.


bigbird from georgia
User currently offlinerc135x From , joined Dec 1969, posts, RR:
Reply 9, posted (9 months 3 weeks 5 days 14 hours ago) and read 5399 times:

Quoting moose135 (Reply 7):
OAT below 20F and we dumped the water

Thanks Moose.

Remember when they would dump the water and it would pool under the airplane and freeze the tires to the ramp? Then it would warm up in the daytime to 30 or so and they would have to reload water, then dump it again. You could play hockey on that ice.


User currently offlinetaxpilot From United States of America, joined Sep 2006, 97 posts, RR: 1
Reply 10, posted (9 months 3 weeks 4 days 20 hours ago) and read 5282 times:

Quoting moose135 (Reply 4):
Took off out of Pease, dragging some F-4s to Europe. 285K gross weight, with water, we used better than 10,000 feet of runway to get airborne. Never got to fly an R-model, but from what I've seen, they are much better performers. Of course, kids flying them these days will never experience the sound and fury of a wet takeoff...

We were Gods - we made water burn!



Mine was on a cool fall morning. Routine, but thumping the departure end arresting cable on rotation does get your attention! Our calculated level off was 800' AGL (normal1000'). I accelerated out to climb speed at 500'.

Good memories.


User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12064 posts, RR: 52
Reply 11, posted (9 months 3 weeks 4 days 13 hours ago) and read 5199 times:

Quoting bigbird (Reply 5):
You had to keep water warm also. When the temperature dropped below a certain point we had to run the MD-3 power units to keep the water on the "alert birds". Also in real cold climates, i.e. Goose Bay, where I was stationed I believe the water was drained. Is this correct? I am not sure as it was a long time ago. I was stationed there in 1965-66.

I remember we pulled alert at Goose Bay when I was at Plattsburgh, Pease and Grissom also pulled alert there.

Quoting moose135 (Reply 7):
Outside air temp below 40F required heaters, OAT below 20F and we dumped the water. Amazing the stuff that you find rattling around your head...

Yeap, been there, done that.

Quoting rc135x (Reply 9):
Then it would warm up in the daytime to 30 or so and they would have to reload water, then dump it again. You could play hockey on that ice.

Actually, you didn't have to reload water after dumping it the night before because temps dropped below 20. The old J-57s were stronger engines than most realized. At EWO weights, usually a KC-135A/Q alert bird could get off the available runway with dry thrust at temps as high as about 38. T/O data was normally computed with a maximum allowable loss of thrust (such as loosing water on one engine), or minimum allowable thrust (dry thrust in cooler weather). IIRC, wet T/O EPR was about 2.85, and maximum dry EPR, in the mid 30 degrees would be up towards 2.65 to 2.70 EPR. I could be a little off on my numbers, it has been 22 years ago. But using reduced thrust take-offs since the 1970s really helped engine reliability.


User currently onlineRevelation From United States of America, joined Feb 2005, 11932 posts, RR: 25
Reply 12, posted (9 months 3 weeks 4 days 13 hours ago) and read 5197 times:

Quoting taxpilot (Reply 10):
Mine was on a cool fall morning. Routine, but thumping the departure end arresting cable on rotation does get your attention! Our calculated level off was 800' AGL (normal1000'). I accelerated out to climb speed at 500'.

Good memories.

Maybe for you, not so much for whomever cleaned your underwear!  

Thanks to all you cold warriors (see what I did there?) out there!



Inspiration, move me brightly!
User currently offlinee38 From United States of America, joined May 2008, 300 posts, RR: 0
Reply 13, posted (9 months 3 weeks 3 days 18 hours ago) and read 5082 times:

quoting moose135 (Reply 4), "Never got to fly an R-model, but from what I've seen, they are much better performers."

John, much better performers? Absolutely 100 percent, and that's quite an understatement! In comparing the KC-135A to the KC-135R, in terms of control, performance, and overall capability, flying the R model was like flying a completely different airplane. In terms of "engine-out" situations, performance was no longer the issue, control was. You would have loved it.  
One of the best decisions the Air Force/SAC every made. Nevertheless, glad you had the opportunity to fly a piece of American aviation history (KC-135A) and thank you for your service to our nation.

Thank you also for your service KC135TopBoom and taxpilot.

e38

[Edited 2013-06-30 11:56:01]

User currently offlinewindy95 From United States of America, joined Dec 2008, 2690 posts, RR: 8
Reply 14, posted (9 months 2 weeks 5 days 19 hours ago) and read 4686 times:

Quoting KC135TopBoom (Reply 11):
IIRC, wet T/O EPR was about 2.85, and maximum dry EPR, in the mid 30 degrees would be up towards 2.65 to 2.70 EPR. I could be a little off on my numbers, it has been 22 years ago

Dry Thrust when trimming the engine was 1.60 with wet being 1.81.



OMG-Obama Must Go
User currently onlinemoose135 From United States of America, joined Oct 2004, 2245 posts, RR: 11
Reply 15, posted (9 months 2 weeks 5 days 18 hours ago) and read 4675 times:

Quoting windy95 (Reply 14):
Dry Thrust when trimming the engine was 1.60 with wet being 1.81.

Wet EPR on take off was 2.83. Dry was usually 2.20+ more on colder days, but I'd have to dig out my Dash-1 to look it up...



KC-135 - Passing gas and taking names!
User currently offlinewindy95 From United States of America, joined Dec 2008, 2690 posts, RR: 8
Reply 16, posted (9 months 2 weeks 4 days 20 hours ago) and read 4533 times:

Yes it is 2.83. Do not know why I put a 1. For the engine trims we put in the dry value and when we engaged the water it needed to come out to the 2.83. Being the fuel control guy and lying underneath the engine during the trim was not fun. Usually called for a 12 pack afterwards back at the dorm.


OMG-Obama Must Go
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12064 posts, RR: 52
Reply 17, posted (9 months 2 weeks 3 days 23 hours ago) and read 4437 times:

For wet thrust on the J-57 equipped KC-135 was to set 2.83 EPR initially, then reset to 2.35 once you accelerated though 30 KIAS on the runway. It was similar on dry thrust T/Os, set the EPRs at an initial EPR reading, then reset to a slightly higher value once past 30 KIAS.

User currently offlinerc135x From , joined Dec 1969, posts, RR:
Reply 18, posted (9 months 2 weeks 2 days 23 hours ago) and read 4369 times:

Just to clarify I believe the procedure was to set dry takeoff EPR, start the water, and then set 2.83 EPR (TRT-takeoff rated thrust). This setting remained in use until water runout during the acceleration phase of the initial climb out, at which point climb EPR (normal rated thrust) was set.

For heavy weight water takeoffs, especially those associated with an HHD (higher-headquarters directed, meaning "get it done") mission, we started the water while stopped and didn't start rolling until water had kicked in on all four engines. Sometimes it didn't, and because the actuators were in the throttle quadrant to detect throttle position, you could bang on the quadrant with your fist and sometimes get the water to start if it was lagging on one engine.

Some pilots never did rolling water-injected takeoffs because (1) if water was needed then they wanted to make sure it was working or (2) if they needed to dump the water for some reason it should be done while stationary given the several minute dump time, decreasing the aircraft weight by 5500 or so pounds, IIRC.

Incidentally, the switch to start the water was in front of the co-pilot's left knee. Pushing the switch UP started the water, pushing it DOWN dumped the water. That was a mistake NO copilot ever wanted to make, but it did happen on occasion. Once started, dumping water could not be stopped.


User currently offlinewindy95 From United States of America, joined Dec 2008, 2690 posts, RR: 8
Reply 19, posted (9 months 2 weeks 2 days 22 hours ago) and read 4358 times:

Quoting rc135x (Reply 18):
Just to clarify I believe the procedure was to set dry takeoff EPR, start the water, and then set 2.83 EPR (TRT-takeoff rated thrust). This setting remained in use until water runout during the acceleration phase of the initial climb out, at which point climb EPR (normal rated thrust) was set.

Correct and this was the same method used when trimming the engine. Set the dry EPR and then turn on the pumps and if it wsa timmed right it would come out to 2.83. We would have to keep adjusting until we could meet that target.



OMG-Obama Must Go
User currently offline135mech From United States of America, joined Oct 2006, 396 posts, RR: 4
Reply 20, posted (9 months 1 week 6 days 19 hours ago) and read 4169 times:
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Hey guys, sorry haven't chatted in a while - have missed your knowledge!

WOW, distant memories! As a crew chief, but never actually got to perform "alert" sadly, watching the MITO's on the B-52G's and KC-135A's at Fairchild at the time was "awe"some. Running ground man on water runs was always more "bone-rattling" then the R-models, but both planes always amazed me! For those of you that never got the pleasure of experiencing the hoovers, their spin-up is just inspiring!

Over the years I was priviledged to work all of the engine models due to my first 2 years in England [J-57's, TF-33's - 4 different versions, and the blessed F108/CFM-56-2B].

I was always amazed at the "courage" of the first two jets to go! I remember the LAST EVER KC-135Q take off out of Rhiyad, in 140+F and he took EVERY BIT of that shorter narrow runway next to us and that black smoke lasted forever!

We literally doubled the power with the upgrade, went from 11K thrust to 22K thrust per engine. Each engine is rated individually and a lot of them are around 21,800 but the CFM-562B is a 22K class engine.
[Edited for spelling]

Regards,
135Mech

[Edited 2013-07-11 10:26:30]

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