Originally Posted by
Chris Scott
Looking forward to your ten cents' worth, Jelle!
Thanks Chris!
As a bit of context for power demands, the 777 has two 120kVA generators for a total generating capacity of 240kVA, the 787 uses four starter/generators of 250kVA each, for a total of 1000kVA. Compared to that, four times 48kVA is not a lot, but it was more than what the 707 needed...
I realised that fail safe/safe life are dated terms, but they were in vogue when the VC10 was designed. I don't know the specifics of all the modern airframes but on the 737 family, Boeing managed to increase the available life on a fuselage from 60,000 to 75,000 cycles when they went from the Classic Generation (-300,400,500) to the Next Generation (-600 and on) models. Long range airframes can take a longer time to reach such a cycle limit. A 747 was originally designed for 20,000 cycles, 60,000 hours or 20 years. On that airframe it is not an absolute limit (a 747-100 surpassed 100,000 hours in 1996) but it takes expensive repairs and modifications to make sure you can keep it in the air. There is an old
FlightGlobal article here that includes a list of several types including design life numbers. The 787 was designed for 44,000 cycles (don't know the hours) but a test airframe went through a simulated 160,000 cycles without any cracking. While that validates the use of composites to counter fatigue related structural issues, the big question is whether other influences are going to age the airframe in any way as it clocks up the hours. Anyway, the point I was trying to make is that you better have a good thought about a realistic design life for the airframe from the start as it may help in keeping the weight down as well as the testing costs.
Things have gone a bit quiet on the plans to get the Dunsfold VC10 back in the air again. While I would not recommend restarting production on the VC10, putting one in the air again to provide AAR for a while may well be a worthwhile effort. And if it does work out, we may well get to listen to the roar of four Conways again...
Great photo of ZD241 there Tony