Aircraft usually are not certified to takeoff in excessive temperatures, usually around the 39-42 degree mark. Some are certified a tad higher up to around 46 degrees. This is typically due to reduced thrust available at higher temperatures. Some composite aircraft do have an internal temperature gauge which restricts high temp takeoffs, the composite will flex too much. Once airborne, the outside temperatures just get colder, down to a minimum of around -50 degrees.
"What are your thoughts on the new Boeing 787's and their use of up to 80% carbon fibre in overall construction?" Fingers crossed they know what they are doing! :rofl: I'm sure Boeing has done massive amounts of testing etc over & above what they are required to do by law. Still I personally would like to see them buzz around for a few years before I go for a ride in one (to prove themselves) - mind you then they COULD get weaker with age
They already have proven themselves. The designs have been around for a long time. Its the first time its been used as the primary material in a transport category aircraft, but not the first time for use in an aircraft. Weaker with age, everything gets weaker with age. There are overhaul times for everything. Maintenance schedules are massive, I wouldn?t be concerned in the slightest. Airliners in the past have been lost due to fatigue in metal components and poor designs. Boeing have tested the shit outta it, and as a result it has been delayed a number of times. It will still have a max temp takeoff restriction in a similar range to most others in its class.
I am aware they have been various light aircraft - made from CF for years, there are some prominent light 2 seater kit aircraft on the market. Particularly The 'Sting' as I mentioned before. There in lies my concern, Commerical aircraft are incomparable to light aircraft. The amount of fatigue stresses, heat stresses, cycles (take off and landings), gross loading etc are huge. Aluminium is alot more forgiving and gives obvious signs / prior warning when fatigue and corrosion begins to present itself. CF isnt as forgiving. Are these Wet wings? How does CF react with fuel (say a leak from a bladder etc). How well do they cope with radiant heat in an engine fire etc. Also carbon fibre conducts electricity very well - how do they fair with lightning stike? I know all these things have been tested and what not, but such things are usally only discussed publicly - in hindsite of an accident. I would love to know what kind of TBO the wings themselves are said to have. Best regards,
Having personally seen the results of a mild lightning strike on a carbon fibre airframe I would suggest even on an aircraft that size one big strike = end of life for aircraft. Yeah they have bonding straps & static wicks & this that & every other thing but end result after a strike was bad very very bad, the craft carried on flying & landed safely but it was seriously damaged, engines had to be replaced, ECUs replaced, avionics replaced/repaired, large sections of the nose had to be repaired, the wing tip literally blew apart! It was all fun & games & big $ Anyone remember the Airbus crash in the states that time the vertical stabiliser sheered off under high load (wake turbulence from another large jet they said in the end)
Evil Twin, I hope youre not suggesting that you happen to be the first individual to have ever thought up these concerns? And that at not one stage in the immense and massive multibillion dollar engineering project, you are the first to bring these issues to light? Everything you have mentioned has been addressed. The reason that predominantly only light aircraft of 2-4 seaters have used CF is because that what the market dictates. There have been no new release mid-sized regional type aircraft released since the 80`s. The 747 was released in the 60`s and is still going strong. Fatigue and stress is all taken care of in periodic maintenance inspections. The most punished aircraft I can consider in cycles, operating time, G loadings and landing stresses is a fibreglass semi monocoque aircraft. These aircraft are limited to a 12,000 hour TBO wing. At 6,000 hours they need to be returned to the factory for an internal inspection. CF conducts electricity significantly less than any metal counterpart. Whereas in an all metal aircraft, the electricity can flow through all surfaces relatively well without damaging much. That is unless its a large enough strike like a mega strike. The problem with composite is that it is highly resistant and will allow the electricity to travel though the rest of the metal, which can cause serious damage to control cable, hinges... whatever. So they employ Lightening Strike Protection, similar to that of any large city building. It utilises large metal pathways for the electricity to flow in and out of the aircraft without damage. Composite fuel tanks have been around forever. That no new news. Imm unfamiliar with what the 787 uses a wet or dry wing. The composite a/c I know all uses wet wings without an issue. It seems a little discrediting, that you would trust transport aircraft manufactures and their operators for decades, and then when they release newer and better tech for the advancement and safety of everyone involved, you would question the same processes that have kept the industry going for so long.
Look familiar? Off the SAU GB thread. APCT shafts same as Chris's. Was supposed to be the 2000ft.lb one too. Busted on the first drive, 1st to 2nd change at about 4000rpm at approx 3psi of boost. R34 GTR with Holinger. Apparently the shaft was made from the wrong material... Might be worth chasing up Chris. Jim Leslie is the guy to talk to, he is the MD of the company. Apparently very reasonable to deal with. Gave the guy a new shaft and his money back Contact details too: email: jleslie@acpt.com Phone: 00111714-895-5544 If anyone wants to check out the thread here it is: Clicky GB was done through STS too Causes some headaches... Shitfight for that starts about page 9, mainly to do with currency fluctuations. Shitfight for bodgy products starts about post 580. Few people had trouble with vibrations too, one shaft was way out of ballance. Hmmm.
Hmmm I think I will bolt my PST carbon fibre up now and give it hell at full boost. Was going to wait til turbo upgrade but am curious now to see if its more of a ACPT fault/problem (which is the only ones I've seen broken)
Ask the manufacture not me, you could touch the exhaust after it was running for hours and it would be cool to the touch, maybe thats why they said to keep it out of the sun? Cause they had something protecting it from the hot exhaust gases?
Interesting pics Chrispy. If you look closely the contruction is bias layed unidirectional cloth. Uni cloth is a lot cheaper than woven cloth. whihc is whay they have used it most likely. But see how it has failed. It has torn between the uni strands. If this had been bias layed woven cloth it probably wouldnt have failed as the cloth is woven and interlinked. In this shaft you are relying on the resin between the layers to bond them together. This could be made a lot better with some thought. Doesnt seem to be any longtitudinal layers that I can see. Must'nt be all that strong longtitudinally. Also seems light on for cloth quantity IMO.
Yeah why not, PST ones are spose to be better quality than the APCT shafts though (from what I've heard)
Thanks for the post Chris. I have already e-mailed James and now I'm waiting on my second reply. He asked for some pics of the damage and hopefully it will all work out ok. I now have the stock shaft installed and its handling the power pretty well.
Umm noo I think I mentioned that when I said "I know all these things have been tested and what not, but such things are usally only discussed publicly - in hindsite of an accident." Boeing 777? sorry thats a widebody Yes yes yes - hence the reason for speculation - can I not speculate? I would speculate and say that lightning also has a heat element to it. I am not claiming any facts here by any means! Noted I never said I didnt trust anyone, I speculated and asked questions. I didn't tell anyone not to fly. How often has history shown us that "aircraft manufacturers" or any industry experts have gotten it wrong. Either through under engineering, overengineering disregarding unlikely or 1 in 100 events etc and people who have put their trust in such organisations have lost their lives? One would imagaine something as simple as a CF driveshaft should be a simple straight forward engineering process. And people pay good money in trusting these things are manufactured and tested to certain standards as well. Thanks for your imput WhiteKnight - I don't want to start a flame war or anything.
I was looking for this when the subject was current, but only just found it. I particarlly like the last comment of this. (Courtesy Meyers Aircraft Company)
