Fortunately, the runway appears to be long enough that you will get airborne simply due to the runway dropping from below you due to the curvature of the earth.
Joking aside – for the abort, pick an abort point of the approximate factored landing distance from 50ft – if you haven’t achieved 50ft at that point, you can still land back. No point in barreling down the runway to get airborne only to find out you won’t climb.
Check your tyres – they’ll be working quite hard.
Oh, and all the stuff above. The lift fairies that give you IAS are exactly the same ones that tickle the wing. Stick by book speeds.
I don’t know about the Dakota specifically (so check the POH!) but all other constant-speed non-turbocharged piston aircraft I have flown have a “best power” mixture at 100F rich of peak. Assuming you’ve got an EGT, I’d do a static full-power runup and lean to that EGT value.
When doing such a runup make sure you’re not on gravel or loose ground, but on solid and clean concrete or tarmac. It’s all too easy to pick up small stones, debris, sand and so forth. This can damage the prop and even clog up your air filter. And in those situations you don’t even want to think about carb heat or other alternate air checks that bypass the air filter.
A_A agree, it is a good rule of thumb, but at some point your excess power becomes negligible and you may not climb out of ground effect.
Flying at dawn or at night in the coolest possible air will create some safety margin.
Archie wrote:
You might want to define an Acceleration Check Point. At half the ground roll (TORR) your should have achieved 2/3 of your lift-off speed. (simple mathematical equasion) Otherwise you won’t make your expected TODR.
This is an approximation which is valid if acceleration is more or less constant. I would not rely on that on a departure from Addis Abbeba.
Thanks all. We’re definitely planning on an acceleration check point.
This morning we’ve had confirmation of our fuel in Addis, we’re getting a ~ 55 gallon drum (unfortunately it can only be ordered by the drum and is very expensive). That will give us full tanks (we should have landed in Addis with at least 20 – 25 gallons) and with two people will be still be well below our MTOW.
If anyone is interested you’re more than welcome to follow the trip on my Instagram account, just request to follow (https://www.instagram.com/nicolassharp/)
You might want to define an Acceleration Check Point. At half the ground roll (TORR) your should have achieved 2/3 of your lift-off speed. (simple mathematical equasion) Otherwise you won’t make your expected TODR.
I have been flying a Piper Archer 2 from Addis Abeba towards Yemen. The runway was long enough for our overweight aircraft (ferry tank) to rotate, but we had quite some trouble to get over the mountains around it. It can be tricky. Temps can be high. Leaning for max performance helps while trying to climb out. I would take all the fuel you can get.
I would agree with the sentiments on fuel. The major rule of flying in remote areas is take as much as you can assuming long enough runways.
I was in South Africa not too long ago, dealing with similar issues. We had 8,500 ft DA almost every day, we took of with a PA28-140 with 3 people on board, bags and fuel to the tabs. Acceleration was less than stellar, you need a bit of runway.
Dakotas are quite common down there because they can carry so much and have plenty of reserve power. As Bosco wrote above, I’d take all the fuel I can w/i W&B limits.
Lean slighty directly after start (~2cm), lean to peak rpm during the run-up (when the rpm starts to come down, push it back in ~5mm / 1/4").
Rotate at your normal speed, but level off as soon as airborne 2-3m above the runway to pick up speed before the actual climb.
