Ship 741At this point it is hard to believe anything that comes out of Boeing regarding the 787. A mainstream news organization has more credibility than them, and by them I mean the whole team: labor and management.
Sadly, with only one other major airframe manufacturer, prospective customers have few alternatives.
Ship 741A bit of a technical one here, but have heard much about how the triple core Trents and RB-211 suffer much less from degradation in performance and fuel burn than the twin core competitors such as the GE-90.
My question is partly how does this happen, and also what kind of percentage degradation is there, and how do the two sets compare over time fuel burn wise ( I understand the GE-90 has a lowere fuel burn initially), obviously this is pretty vague with various models (and for different aircraft) available, but is there some general rule?
Cheers
I will be the first to admit that there is a lot I do not know about the topic, but perhaps I can contribute some information.
Most airlines have some way to capture actual fuel burn on each flight. This data gets fed back into the computer and a performance factor for each individual airplane is continually updated (the computer calculates planned versus actual). As the burn gets higher, due to engine wear, weight of the airplane changing, dirt accumulating, etc. the flight planning system is fed this data and gives a little more fuel to successive flights. Of course, things like an engine change, or an aircraft overhaul/interior modification cause the calculation to be reset. The initial setting is normally from manufacturer supplied data.
The wear of an engine can be monitored within fractions of percentage points. As I say, I am not an expert, but I believe it would be rare for an engine burn to increase more than 5% due to wear alone, but that can be significant on a long haul flight. I must say that I am unaware of an degradation differences due solely to the number of spools.
Keep in mind also that engines on newer airplanes (330/340/777/etc) have extensive on-board computer monitoring capability. The data captured is very detailed, all the critical parameters and then some. This data can be read in real time at the airline headquarters or wherever their engine monitoring is done. It is possible to see an individual engine deteriorating to the point where it would fail. The trick is to run it as long as possible with on-wing maintenance and then change it before it fails. This capability is an important factor in the success of ETOPS.
Ship 741WOW! Great work.
The only thing I remain curious about is the undersea component. Every time I see the charts of the surface capability of the aircraft and missiles, I wonder about the similar chart showing under-sea capabilities. The very large number of ASW helos that the Russian carriers embark versus the relatively few carried aboard the USN carriers leads me to believe that the USN has much more SSN capability attached to its CVN battle groups. As secretive as the “Silent Service” is, I don’t suppose there is much hard data available on true SSN capabilites, let along information on operational doctrine. (For that matter, I’m still wondering about doctrinal difference WRT USN employment of 1 seat versus 2 seat SH’s.)
Ship 741I hope this isn’t another case of a union shooting itself in the foot…
or wounding the goose that lays the golden egg…
I don’t think there is any doubt about it….this is in fact exactly what the union has done. My prediction is that the company will be further incentivized to outsource work AND move more work away from Seattle, and the union will attempt to negate this through political activity from a labor-friendly congress and president. The fight goes on.
Ship 741For really longhaul you need more engines in order to be efficient. It all boils down to the engine failure on take off scenario. Let me explain…
If a certain aircraft needs 60,000 pounds of thrust in order to achieve the minimum engine out performance after take off, then that aircraft will need 2×60,000 pound thrust engines for normal operation. This way it can achieve the engine failure criteria but you have an aircraft that produces 120,000 pounds of thrust at full power. If that same aircraft had been designed as a 4 engined aircraft it would need 4×20,000 pounds of thrust engines. Now in the event of an engine failing it would still have the 60,000 pounds of thrust required to climb (and the performance loss would not be so marked). The 4 engined aircraft would have a total all engines working max thrust of 80,000 pounds as opposed to 120,000 for the twin. If it takes say 40,000 pounds of thrust to maintain the aircraft in level flight in the cruise, the 4 engined aircraft is running its engines closer to optimum than the twin engined aircraft. This is why the A330 is ideal for hopping from the UK to Florida but the A340 flies to the far east, etc.
The post above must be the most misleading post in the history of aviation. I know it’s several years old, but I just ran across it.
The reality is that the twin is ALWAYS more efficient. The block fuel burn per seat is ALWAYS less with the twin. This is why the 777 has outsold the 340, why the 330 is selling so well, and why the 787 and 350 will both be twins.
No one who is a serious student of aviation doubts that the twin is more efficient, it is such a slam dunk that one does not even have to post the data to “prove” it here.
Ship 741Here is a link for the Frank comments:
http://www.southcoasttoday.com/apps/pbcs.dll/article?AID=/20081024/NEWS/810240332/-1/NEWS10
“In a meeting with the editorial board of The Standard-Times, Rep. Frank, D-Mass., also called for a 25 percent cut in military spending, saying the Pentagon has to start choosing from its many weapons programs, and that upper-income taxpayers are going to see an increase in what they are asked to pay.”
IMHO, there is no way that a could of big defense programs don’t get whacked, no matter who gets elected. IMHO, more get whacked in an Obama presidency, the question is: which ones survive? Who ya gonna hitch your wagons to?
Ship 741Here is a link for the Frank comments:
http://www.southcoasttoday.com/apps/pbcs.dll/article?AID=/20081024/NEWS/810240332/-1/NEWS10
“In a meeting with the editorial board of The Standard-Times, Rep. Frank, D-Mass., also called for a 25 percent cut in military spending, saying the Pentagon has to start choosing from its many weapons programs, and that upper-income taxpayers are going to see an increase in what they are asked to pay.”
IMHO, there is no way that a could of big defense programs don’t get whacked, no matter who gets elected. IMHO, more get whacked in an Obama presidency, the question is: which ones survive? Who ya gonna hitch your wagons to?
Ship 741To be honest, it wouldn’t be fuzzy bunnies and lollipops with McCain either. He seems to take delight in kicking the Pentagon and defense contractors in the teeth. Witness his conduct in the Boeing tanker lease deal.
True dat. He saved the taxpayers 6 billion by stopping the corrupt Boeing lease deal. But why waste time trying to figure out what he will do when every poll has Obama winning?
Ship 741To be honest, it wouldn’t be fuzzy bunnies and lollipops with McCain either. He seems to take delight in kicking the Pentagon and defense contractors in the teeth. Witness his conduct in the Boeing tanker lease deal.
True dat. He saved the taxpayers 6 billion by stopping the corrupt Boeing lease deal. But why waste time trying to figure out what he will do when every poll has Obama winning?
Ship 741Sorry, but is this issue appropriate for an aviation forum?
I considered not posting it, or rephrasing it. But the bottom line is that the military aviation programs are gonna have to be cut because of the increasing cost of the domestic programs. The two are inextricably linked…..guns versus butter. Does anyone not see military aviation suffering in an Obama Presidency?
Ship 741Sorry, but is this issue appropriate for an aviation forum?
I considered not posting it, or rephrasing it. But the bottom line is that the military aviation programs are gonna have to be cut because of the increasing cost of the domestic programs. The two are inextricably linked…..guns versus butter. Does anyone not see military aviation suffering in an Obama Presidency?
Ship 741But with its APG 79 and application of stealth technology (realistically, bettered only by the F-22 and the still in development F-35), the shoot first window opened up for a Block 2 SH renders the “better” airframe performance of some of its contemporaries irrelevant.
That was my kind of my point…..its irrelevant to quote one or two aspects of a particular fighter’s performance envelope, when other factors can be game changers. The SH is an example of an airplane that can be bested in several important performance arenas, but it is still formidable due to the “system” around it. The important points are the training, support, AAR, AWACS, sensors, missiles, doctrine, mass, etc, etc, etc.
Ship 741looks like it’s already affecting them:
Ship 741I live in the southern U.S. and did a down and back to Grand Cayman a year or two ago on the jumpseat and managed to snap this pic over the Captains left shoulder with my cellphone. The bungee for his earpiece cord kind of obscures it but I thought it was cool nonetheless.
Note: 7000 ft runway with water off the end and no taxiways….must back taxi on the runway. We got a flight idle descent from FL380 and were cleared to land a long way out due to no other traffic. When we departed an hour later, we were cleared to takeoff and climb to FL390. Kinda strange to have such unrestricted clearances nowadays…don’t often get a clearance to FL390 from the tower.
Ship 741I also wonder if the RAF birds will get a better kit? It seems that the last time the RC’s received a major upgrade was the early 80’s (though I am far from an expert on the topic). Given the rate of electronic/computer progress, the 1980’s is the relative stone ages.
If the “guts” of the existing USAF RC’s are really that old, I would be surprised if spares aren’t becoming a real problem also. Maybe the RAF birds will be the impetus for an upgrade of the whole group?
Hey, just thinking out loud here…..
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