The only speed effected by this is VR, but you still use the same V speeds, is a slow rotation allowed prior to reaching V2?
Photons, I don't think you are correct . It may be permissable to use the same speeds but in reality the V1 will be different, you've already mentioned that Vr will be different, and by my way of thinking V2
may change based on the different Vr and the increased rate of accelleration.
I would really like to see someone like Mad Scientist do a comparison of two thrust settings to see what the differences are. Might be a bit tricky to get across on here though.
To determine whether to use a bleeds on or off takeoff, you MUST include 4,000 Ib's to you actual gross weight. A bleeds on takeoff with the assumed method must also include this correction.
I'm not sure what you're saying here. I think there may be some sort of language barrier. Are you talking about "padding " the figures or are you saying that with bleeds off you can lift 4000lbs more? From the charts I use you can either do it or you can't, the performance engineers have already done the maths on what can be lifted. The only reason we would add any weight to our "actual gross weight" as you say, is to avoid having to do the numbers again if our zero fuel weight changes between our provisional load sheet and our final load sheet.
To determine whether to use the assumed temp method, refer to your flex temp gw column of the runway in use.
I think everyone commenting on this knows how to do the basic calculations on a day to day basis. What I am hoping is to get a bit better understanding of exactly what the relationship is between thrust and weight and the V speeds. I will do some research tonight and try and impress the clever ones on here with my knowledge tomorrow
