Jackbr From Australia, joined Dec 2009, 616 posts, RR: 0 Posted (4 months 10 hours ago) and read 4638 times:
I've seen a lot of videos of 707s taking off - many show the aircraft having its brakes held until the engines seem to reach full take off power before being released. I've only seen one video (a 1989 video of a private 707-123B) making a rolling take off.
Were rolling take offs rare on the 707 (and DC-8, CV-880 etc)?
simairlinenet From United States of America, joined Oct 2005, 738 posts, RR: 1 Reply 1, posted (4 months 9 hours ago) and read 4615 times:
Not knowing for certain, my initial suspicion is that runway lengths in that era were in many cases not sufficiently extended to allow for rolling or idle stop takeoffs.
nonfirm From United States of America, joined Sep 2005, 434 posts, RR: 0 Reply 2, posted (4 months 9 hours ago) and read 4601 times:
Check this link here. This is for a Virtual Airline but it has a takeoff procedure in it.Here is part of the section.Again I do not know how accurate the info is. http://www.vpiaheritage.com/707procedures.pdf
Standard Takeoff Procedures
Standard takeoff procedures include the following:
• The captain will use nosewheel steering to 80 knots.
• The first officer will hold the nosewheel on the runway and keep the wings level to 80 knots.
• The pilot not making the takeoff will call out “Airspeed, 80 knots, V1, Vr, V2, Positive climb,
and 800 feet.”
• The engineer will automatically switch to an operating generator if essential power is lost.
• The pilot making the takeoff will advance the throttles to about 0.10 below the target
takeoff EPR value. The engineer will trim the engines to takeoff thrust and monitor the
power throughout the takeoff regime. Once set, the captain will position his hand on the
throttles until V1.
• The captain will make any decision to discontinue the takeoff and will execute the RTO
procedures.
• The captain will remove his hand from the throttles at V1.
Takeoff Positioning
Takeoff performance calculations presume the use of all available runway. Good judgment
dictates that a minimum amount of runway be used in positioning for takeoff, especially when
TOGW is runway-limited.
Applying Takeoff Thrust
On all airplanes, set the chart rolling-takeoff EPR values, with appropriate turbocompressor
corrections, on the EPR gauges. When aligned with the runway:
• Advance throttles smoothly.
• Pause until all engines have accelerated and are stabilized at 60% to 65% N1.
• If using brakes, ease them off.
• Smoothly advance the throttles to about 0.10 below target takeoff EPR-bug value. Call for
takeoff thrust.
• Between 40 and 80 knots, adjust the thrust to bug value. Do not readjust EPR after 80 knots
except to stay within EGT or N1-N1 limits. During the takeoff roll, the ERP may drop as
much as 0.03 by Vr. Do not adjust or recover for this drop since engine over-boost will
occur. Also, be alert for N1 over-speed on hot weather takeoffs.
This technique of applying thrust permits even heating and expansion of the engines, reduces peak
temperatures and avoids controllability problems associated with asymmetric engine acceleration.
Takeoffs made from a static condition may be made as required. Set static takeoff EPR before
releasing the brakes. Ease the brakes off. All other procedures remain the same. 5
Advancing the number 3 throttle to the takeoff setting will cause an intermittent horn to sound for
any of the following reasons:
• Speedbrake lever out of the zero detent.
• Stabilizer index out of the green band.
• Flaps not in a takeoff position.
Northwest727 From United States of America, joined Jul 2005, 475 posts, RR: 1 Reply 3, posted (4 months 4 hours ago) and read 4492 times:
My guess is that early turbine engines spooled up rather slow, maybe by holding the brakes they allowed the thrust from the engines to stabilize, but that is a guess. 411A would answer this question perfectly as soon as he signed on, if he was still with us, unfortunately...
clydenairways From Ireland, joined Jan 2007, 683 posts, RR: 0 Reply 5, posted (3 months 4 weeks 1 day 6 hours ago) and read 4055 times:
Quoting Jackbr (Thread starter): I've seen a lot of videos of 707s taking off - many show the aircraft having its brakes held until the engines seem to reach full take off power before being released. I've only seen one video (a 1989 video of a private 707-123B) making a rolling take off.
For any aircraft that is performance limited off a particular runway, you may see that happening. But it was much a much more common practice with older aircraft, especialy when they were heavy. 707,DC8,747-100,IL62 etc
But i've also seen 737,EJets,Airbus do this off very short runways.
I think you've seen a lot of Saha Air 707 clips, who do hold the brakes on most takeoffs. It was never standard 707 practise, and Saha do it because those engines are just so old, and have so many locally-made parts inside them, it just gives them a decent few seconds, and sometimes quite a few seconds, to spool everything way up and really watch the indications and totally establish that all four are stable before committing to a roll. Once the aircraft is moving, there are other things to look for, so it does make sense.
gr8circle From Canada, joined Dec 2005, 2836 posts, RR: 5 Reply 7, posted (3 months 3 weeks 2 days 15 hours ago) and read 3231 times:
I did a lot of flying on the B707 back in the 70's when I was small......AI 707's, both RR and P&W powered......takeoffs were always with power building up with brakes on and then commencing TO roll....don't ever remember a rolling takeoff.....that's something I only encountered when I started flying on more modern planes in the 80's.....
BAe146QT From United Kingdom, joined Sep 2006, 989 posts, RR: 0 Reply 8, posted (3 months 2 weeks 4 days 22 hours ago) and read 2817 times:
Obligatory on-topic bit:
I've always assumed, judging by the movement of the aircraft, that brakes weren't applied during the final run-up at take-off, since the aircraft is rolling at the time. Clearly that's based on adult observations where I had any idea what might be going on up front. I can't say I remember what my 747 experiences were like in the mid-70s.
Quoting Northwest727 (Reply 3): 411A would answer this question perfectly as soon as he signed on, if he was still with us, unfortunately...
Apologies for being off-topic, but what happened to him please? I've been away from the site for a while and so don't know who has left and why.
Fabo From Slovakia, joined Aug 2005, 826 posts, RR: 1 Reply 9, posted (3 months 2 weeks 3 days 19 hours ago) and read 2669 times:
Quoting BAe146QT (Reply 8): Apologies for being off-topic, but what happened to him please? I've been away from the site for a while and so don't know who has left and why.
He left, as they say, for the Western skies
France 1789, Eastern Europe 1989, Northern Africa 2011
B777LRF From Luxembourg, joined Nov 2008, 719 posts, RR: 3 Reply 11, posted (3 months 2 weeks 1 hour ago) and read 2339 times:
Been many, many, years since the last time I was onboard a 707 (well, a 720 actually) and rolling take-offs were common operating from homebase (long runway) whereas standing the engines up while holding the brakes were common when departing from down route (short runway, usually very warm too).
I've been onboard MD80s that were held on the brakes while the engines were spooled up, and I've done rolling take-offs as well.
On the B757s I used to fly we were initially not allowed to do rolling take-offs, but can only recall a few instances where the engines were spooled up while holding her on the brakes. Later on we got a new CP who didn't have a problem with rolling take-offs, and the SOP were changed accordingly. After that rolling take-offs were not unusual if the Captain was PF (no tiller on FO side, so the Skipper did all the taxying), whereas FO take-offs were usually from a stand still. But even that wasn't cut in stone; as a FO I did rolling take-offs as well.
I guess the answer is, as is very often the case in aviation: It depends .....
From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
musang From United Kingdom, joined Apr 2001, 686 posts, RR: 8 Reply 12, posted (3 months 1 week 5 days 20 hours ago) and read 2155 times:
Interesting.
We fly Classic 737s and a few years ago one crew set t/o thrust while stationary. It blew chunks out of the asphalt runway which impacted the tailplane (stabiliser) leading edge and belly. A subsequent enquiry to Boeing by our Management provoked the response that the manufacturer saw negligible t/o roll reduction from brakes on t/o thrust launches when compared to setting thrust with the brakes off. We are now advised not to set t/o thrust on the brakes, but having said that we don't serve any really short runways.
The other consideration for under-wing engines is of course FOD.
However, advice on the 146 was that on short runways, setting t/o thrust on the brakes was what the performance was predicated on. On short, slippery runways (e.g. compacted snow) we had to increase to t/o thrust, and if it started to skid, just release the brakes and let her rip.
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