TOFL/BFL Question

[Oldmoparguy1]

Opps, forgot.
Recently saw a program on the Smithsonian channel about the development of the 747. I think it was called Great Planes.

 

[Mr Nice]

fdcg27,

Are you a GA pilot ?
I notice you comment quite often in various aviation threads.

 

[fdcg27]

Well, I referred to myself in a post above as having a simple GA single mind.
To me, anything that flies is magic, whether it be a few rented hours in a C172 on a pretty June day or sitting in the back of an airliner.
I've gotten to fly in a hot air balloon as well as a Tri-Motor Ford and I even plan our travel to try to get types we haven't flown on before as well as through airports we've not visited before. My wife couldn't care less as long as we get where we're intending to go close to when we intended to be there.
I've always loved aircraft and flying.
To me, a day at the Air Force Museum, which is not too far from us, is magic.
A weekday is best, since there are no crowds.

 

[Astro14]

Thought of this discussion as I took off from Maui last night.

Runway 2. 6995' useable runway. 4kts XW. 0HW. 21C. 30.06". 233,300# airplane.

For reduced thrust, of 1.66 EPR, v-speeds were:
V1 135. VR 139. V2 143

For max thrust of 1.77 EPR, v-speeds were:
V1 121. VR 136. V2 143

The takeoff safety speed of V2 is the same, and is really a function of climb performance (which is based in weight, CG, atmospherics, slope, etc.).

But there is a slightly lower VR with more power -which makes sense with a higher acceleration rate. Rotate just a bit sooner to intercept V2.

But here's the key point: with more power on the airplane, and greater acceleration, the decision to go is made SOONER with MORE runway in front of the airplane.

Clearly, with higher thrust, the airplane rotates with more runway remaining. In a balanced field calculation, you would have a higher V1 at higher power. But we don't do balanced field...

In this case, the airplane has the performance to "go" at a lower speed when it has more power. That greater runway in front of it, and the higher engine thrust, allows for an earlier V1 go decision.

With an 80 foot cliff off the end of the runway, I'm OK with biasing towards the go decision...

Cheers,
Astro

 

[DeepFriar]

Looks like our 747 discussion is sadly timely. United said today they are retiring the rest of the jumbo fleet by year's end. With Delta doing the same, the end is now clearly in sight. What's that leave? BA? A few freighters? Supportability, sustainability for the Air Force One project not enhanced by evaporating fleet base either I'm guessing. That procurement will probably now have to include a concurrent lifetime spares buy that adds much expense to a two unit buy. If I was Boeing I would be pitching a recapitalization program that would include replacement of all the command post aircraft (NCAP, Looking Glass, et al) as well.

 

[Astro14]

United's announcement was a surprise. It accelerated the retirement date for our remaining 747-400s by a year. The 777-300ER simply costs less to operate and we just bought 14 of them. I anticipate more of those airplanes.

Former airliners generally end up in the hands of freight operators. Lots of UAL 727s, 757s and DC-10s wore FedEx colors after UAL retired them. When an airliner is in the air for 10-20 hours per day, fuel costs really matter. When it's in the air for three hours, cost of ownership, particularly depreciation, matters much more.

You'll see 747-400s in freight service for a long time to come. The older -100s and -200s are almost gone now. The 747-8s will likely end up in freight service as well. There'll be 747s in the skies long after production shuts down.

 

[CT8]

When at work the DC 10 and 747 Freighters would sit all day.

 

[DeepFriar]

The Great Circle Mapper website, www.gcmap.com , has interesting input on the United 747 retirement plans. It has a little history on the fleet evolution over the years (including the 747SPs that were ex-Pan Am) and a snap shot map of some of the old routes. I like that site, simple to use and fun to play with for the geography/navigation interested/afflicted. Good time wasters like, what possible city pair(s) would take you directly over Thule Air Force Base if on the Great Circle Route? No "Polar Routes" for this one. Never heard of Thule? Lucky boy.

 

[CT8]

Originally Posted By: Astro14
One need only look at the sweep angle of the wings to know that the 747 was built for speed.

The 747 was built for awesome ! I love the plane for some reason.Lots of bathrooms maybe. The 777 is really nice and on the outside, the 787 is a very,very pretty girl.