11-15-2007, 11:16 PM #1
What Else Do We Find Interesting???
I have really been interested in jet engines as of late and find it amazing a jet is required to lift off with one engine........just how POWERFUL are these bad boys?? What does it feel like when a bird takes an engine down on lift off?? Oh man I think I'd crap my pants. LOL
11-15-2007, 11:32 PM #2
MD11 one of the bird's I worked on. A single engine is rated at 62000lb thrust at SL.. X Three.
That is with the PW engines.
The GE engine was 61500
The GE's spooled up faster but the PW's had the range.
Tomorrow I will dig up some photos of changing #2 engine in Bakersfield... Talk about a small runway for the MD11....
11-15-2007, 11:35 PM #3
Had some time in on the B1B.. All 100 built.
Four General Electric F-101-GE-102 turbofan engines with afterburners power the B-1B, a long-range strategic bomber, capable of flying intercontinental missions without refueling, then penetrating sophisticated enemy defenses. The aircraft can perform a variety of missions, including that of a conventional weapons carrier for theater operations.
The first operational B-1B was delivered to the Air Force at Dyess Air Force Base, Texas, in June 1985, with initial operational capability on Oct. 1, 1986. The final B-1B was delivered in May 1988.
The B-1B has captured more than 80 world records for speed, payload and distance. The National Aeronautic Association recognized the B-1B for completing one of the five most memorable record flights for 2003.
B-1B Aircraft Facts
Thrust: 30,000-plus pounds with afterburner, per engine
Length: 146 feet (44.5 meters)
Wingspan: 137 feet (41.8 meters) extended forward, 79 feet (24.1 meters) swept aft
Height: 34 feet (10.4 meters)
Weight: Empty, approximately 190,000 pounds (86,183 kilograms)
Maximum Takeoff Weight: 477,000 pounds ((216,634 kilograms)
Speed: 900-plus mph (Mach 1.2 at sea level)
Range: Intercontinental, unrefueled
Ceiling: More than 30,000 feet (9,144 meters)
Crew: Four (aircraft commander, pilot, offensive systems officer and defensive systems officer)
Armament: Up to 84 Mark 82 conventional 500-pound bombs, or 30 CBU-87/89/97, or 24 JDAMS. Also can be reconfigured to carry a wide range of nuclear weapons.
11-15-2007, 11:40 PM #4
RS-27A (rocket engine)
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The RS-27A is a medium-sized rocket engine developed by Rocketdyne for use on the Delta II and Delta III rockets. It is fueled by a kerosene / LOX mixture in a gas-generator cycle. The engine is a modified version of its predecessor, the RS-27; its thrust nozzle has been extended to increase its area ratio from 8:1 to 12:1, which provides greater efficiency at altitude.
11-15-2007, 11:48 PM #5
So you're going down the runway, V1 is passed, the engine croaks and the pilot says, "lets fly!!" Why doesn't he say, "lets stop!"? Because to try to stop may not be possible on the remaining runway. All of that is calculated. Accelerate Stop, Accelerate Go. Both distances are figured into each takeoff.
So after V1, stopping on the remaining runway may or may not be possible. And even if it's obviously possible on a 2 mile long runway, the pilot is trained to takeoff anyhow so that his reflexes are consistent when the crap hits the fan. If he's passed V1 and aborts the takeoff, he's actually violated federal regulations, but the regs also say that he can deviate from the regs to meet the emergency.
An engine failure on the runway actually is NOT life threatening. Redundancy is lost, yes, because you have only one engine left, but that remaining engine is no more likely to fail just because the other one died. In fact, we plan to fly on that one engine for hundreds of miles if necessary to get to a suitable airport for landing if our takeoff airport is too fogged in to return to it. If being on one engine was life threatening, the system wouldn't allow allow the alternate airport to be an hour away.
I've had a couple events at V1...one was a surging engine and it really got my attention. Another engine failure I didn't even notice right away because it rolled back so smoothly and i was climbing out over water which makes it hard to judge climb performance. I knew something wasn't right, but I had to scan my gauges to figure out exactly what was wrong.
I'm in a simulator every 6 months being trained and tested on engine failures on the runway and continuing the takeoff. It's a big deal in real life because most pilots never experience any engine failures in an entire career! So when it happens for real, you pucker up, BUT your training takes over and you realize very quickly that your plane is flying very well and that the procedures work very well, and you bring it around for a landing.
I was in a hotel van crash where another car took us out and caused us to hit a concrete median wall head on at 40 mph...no seat belts...lots of injuries but right away my training kicked in and we evacuated the van like we're trained to evacuate an airplane crash. Training is key to handling emergencies.
Turbine engines are awesome. Tons of power in a very lightweight package. So much better and smoother than piston power and simpler to operate.
Last edited by 1996SLTX; 11-16-2007 at 12:19 AM.
11-16-2007, 12:02 AM #6
Beer, I've got 1000 hours towards an A&P from college and another 2000 hours turning wrenches as an apprentice while I was inbetween flights. That experience has given me a sense of calm and insight when the crap has hit the fan.
Most pilots don't get that kind of systems knowledge and I wouldn't trade it for anything. It also gives me the ability to communicate better with the mechanics so that they get a better idea of what's wrong with the bird.
11-16-2007, 01:23 AM #7
11-16-2007, 01:28 AM #8
11-16-2007, 01:37 AM #9
How is it you wound up a pilot?
Do you get tired of or even feel the g's on take off anymore? That has to be one of the most invigerating feelings (roller coaster is a little brutal in the ride department) and what got me to start thinking about the power required to get a jet off the ground.
I mean we're talking tons of weight pushed down the run way and then traveling for hours on end just to do it again and again.
It just seems the PWC guys could do a little better job with todays technology in terms of reliability and getting the bugs worked out before it winds up in the consumers hands.
Gheeesh, I'm rambling again.
11-16-2007, 08:07 AM #10
On takeoff, the acceleration is cool, but what I never get used to is when the transition is made from rolling on the ground to being airborn and vice versa. That you get cleared to takeoff or land. That once in the air, you have to keep doing your job....you can't quit or you die. That you look out the window and realize that it is that wing plus the power of the engines that is "planing" you through the air. Flying is really special. After 25 years of doing it, much of it is routine and boring, but when you really pinch yourself and take it all in, you smile and give thanks for such a unique and awesome way to make money.
Jet engines mostly get worn out from starting cycles and takeoff cycles. This is because that is usually where the peak temperatures are and the jet engine's life is a balance between max life and max power. If a jet engine was started once and left to run at very low power, the hot section of the motor probably wouldn't ever wear out. But that wouldn't be very efficient so they run the engine as hot as possible (read: more fuel which equals more thrust) but not so hot as to wear the engine out too fast as they are really expensive with exotic metals and tons of labor to build them. Higher temps equal a shorter life between overhauls.
So to save the engine, most of the time when you're a passenger in the plane and sitting on the runway, when the pilot spools up the engine, he won't be using full power. There are charts that compare aircraft weight with runway length, temperature and altitude, and from that a "reduced" power setting is attained and used for that takeoff. Less power equals lower temps on takeoff which equals a longer engine life. A longer engine life saves the company a lot of money plus provides the pilots with a more reliable engine. The first German jet engines had to be overhauled every 25 hours of flight. I've flown motors with 12,000 hours. They are exceptionally reliable.
But even at that reduced power setting, if an engine quits on takeoff, the remaining engine will still pull the aircraft off the runway and over the obstacles AND the pilot can increase power on that engine or the engine may do that automatically.
All of this is figured into every departure. Now runway length is what it is at a given airport, the weather is what is at a given moment, and the motors only have so much power available. So to ensure that the plane can take off on one engine if needed and climb over hills and buildings, then the only variable under the pilot's control is total aircraft weight. There is max structural limit the plane is designed to carry, but that may have to be lowered in order to meet operational factors. Why? So that when plane is going down the runway and below that decision speed of V1 it can stop on the remaining runway, and at or above V1, the plane can continue to accelerate on one engine and take off on the remaining runway, THEN climb out over near and more distant obstacles. By controlling total aircraft weight, we ensure that an engine failure on takeoff is NOT a life threatening event because the plane can fly well and climb and not hit the ground.
There's a really cool seal in jet engines....Labyrinth seal....check it out... http://en.wikipedia.org/wiki/Labyrinth_seal
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