Bobbing on Take off

[Guest totalbetrayal]

Hi folks, my first ever post here so please be gentle ok!I have been using PMDG products for a long time now, so I am fairly competent, especially regarding the 747-400.My problem (just recently) is that when I am on my take off roll, the aircraft (747) will begin to rock / bounce. This increases in intensity until eventually, at around V2, it will "Crash" on the runway.As you can imagine, this is infuriating, especially after an hour or so of planning etc.All weights etc are fine,I also use the popular "Topcat" tool for all take off data.What can be causing this????Many thanxDuncan

[Guest Clansman]

Hi Duncan,Some airports are known to be broken and cause crashes on takeoff rolls. I'm not sure which ones, though.If you tell which airport/runway you're using, I'm sure someone will confirm if it's broken or not in no time.Cheers,Pedro Venda.

[Guest totalbetrayal]

Hi, it was LIRF RW25, perhaps it was due to me holding it momentarily on the Toe Brakes as I brought her up to 40% N1 prior to TOGA ?Duncan

[Captain Caveman 1]

i just had the same problem, and had had it many times. today at LIRF for me to!

[Headley 26]

Must be the runway surface ...There are many topics that cover this subject.Look at this topic ...http://forums.avsim.net/dcboard.php?az=sho...ing_type=searchand also do a search with "runway surface" and you may find many topics related to this problem ...Hope this helps

[Guest totalbetrayal]

ahh, now I see....many thanx to all!Duncs