Vimd

[come fly]

Can anyone tell a bit about Vimd. Just confusing me a little, got a test coming up?
Also if an aircraft rotates 10 kts earlier, what effect does this have on TORR and TODR?
Thanks for your help.

[divinehover]

Vimd is your min drag speed (indicated). It is used in Range and Endurence calculations, not Take Off performance calculations. With referance to the take off you would have to compare Vimd to Vr to see what the effect eould be. If it was the same then there would no effect. If it were lower and you tried to unstick there would be a chance the a/c wouldn't fly. (Weight would exceed Lift). If it were faster the story becomes a little more complex but this has nothing to do with the question.

[mustafagander]

come fly, I don't know about Vimd offhand.
If you were to rotate 10 kt early that would be very likely to blow your performance calculations out of the water. AFAIK it all depends on weight. Ask your performance gurus, DO NOT be tempted to become a test pilot and give it a try.
Do I need to lecture you on what airline pilots do??

[Oktas8]

Vimd is approximately the best range cruise speed for a piston engine aircraft, and approximately the best endurance speed for a turbo jet aircraft. Any beginner's principles of flight text will give you more information.

If you rotate quite early, you may "unstick" earlier, so use less runway to get airborne (reduced TORR). However, you will be airborne at a low speed and high AoA, therefore have high induced drag and be less likely to maintain a normal climb gradient. TODR may be increased.

Just bear in mind that I've given answers based on some wild assumptions on my part, and on some experience of questions examiners like to ask. Mustafagander is correct - don't try this yourself in the real world, where assumptions may kill.

Cheers,
O8