Cool! I have a taker!
Ok, once I am at V2+20 and am in the enroute configuration (flaps up gear up) I can use figure 41 on page 81 of the Performance section of the AFM. Thats the final segment net take off climb chart. Typically at max all up weight and for airfields up to 2000 feet the lowest climb gradient I can get is about 5 degrees and for every value I have checked is better than the flapped gradient (as expected). The really big advantage here is that as you can see from the conditions I am operating at max continuous and therefore I can continue the climb to MSA which you can't do if you are in the flapped condition. This is a huge advantage in terms of workload - the aircraft is easier to fly and you just stick in the autopilot and climb till you're safe. This is how the aircraft was designed to be operated. Incidentally, all the time the flaps are travelling the aircraft is trending towards a better climb gradient (this is the point which took about 40 mins on the phone to Montreal to get clear and I'm waiting for it in writing) but what that means is that if you select flaps up at V2+20 and the engine fails as the flaps start to travel you will ALWAYS be in a better situation but cant prove by how much. In addition, I have a few mins (the remaining of the 5 minutes) left at max thrust before I actually have to reduce thrust to max continuous so am outperforming the data. And I took off earlier along the runway. And I climbed better to the point where I retracted the flap and the engine failed. All of this is to my benefit - unaccounted for and I can't use it in my calculations - but its all gravy...
Once the aircraft reaches 1500 feet OR MSA I accelerated to my enroute climb speed of 190 kts and climb if desired.
Now... one bloke had the guts to take the bet.. you all need to club together to help him pay.
I will try to post the images but need to get them on the t'interweb to do that.
Either that or just send me your email address privately and I'll send them over.
Still all absolutely sure you know whats going on? Ever actually looked at the performance section of your challenger manual CLDRVR? ...thought not...
Just to reiterate. What I have been saying, what the manual tells you to do, is supported in the performance section of the manual (I strongly suspect it is for all the aircraft discussed here) and the fact is that very very few of us know how to use it. Most people don't even know what the different segments are! its all a bit of a joke.