Posts by user "TopBunk" [Posts: 6 Total up-votes: 0 Page: 1 of 1]¶

M2D

A B747-400 at max take off weight (398tonnes) ex LHR would typically have a V1 ~ 155 kts, a Vr of about 170 and a V2 of 182 kts, so not dissimilar V1 speeds, but very different Vr and V2.

[I should add that this figures are for using reduced thrust and about 1.6 EPR on the RB211-524G engines where max thrust is about 1.72 EPR. Full thrust may result in an increased V1, I would guess].

This would suggest similar braking capabilities bearing in mind the differing TOWs involved. As to the relative brake unit weights I couldn't comment, nor therefore on the relative design pros and cons.

Numbers offered purely in response to your request.

Not sure that the landing brake energy is more relevant, the RTO case must involve much more energy - a high speed, greater mass and less room to stop.

Anyway, at Max LW of 285 tonnes, the Vref25 is about 159 and Vref30 is 153, add 5 for the increment and you have the threshold speeds. At a more usual landing weight of 245 tonnes, they reduce to 148/142 +5 respectively.

I feel that I must pick you up there! As I see the guages each engine is consuming 5.4 tonnes/hour. A B747-400 will consume about 10-11 tonnes/hour and not over 20! So over double the speed but double the fuel consumption.

Landroger

If you look here it suggests that it did fly on a limited number of flights.

"Afterwards, "Sierra Delta" started a promotion campaign in Europe and the Middle East. For the Pepsi commercial operation, there were a total of 16 flights (including the ferry flights from ORY) and 10 cities visited. Each flight, except the first and last ones, would have been occasions to go supersonic"

I'll get back in my box then

Sort of .... the aircraft expanded when at Mach 2, so it grew in length etc. This growth translated itself into the gap that the hat was put in. When it cooled on decel/descent, the gap closed wedging in the hat.

Simples...