Ibra wrote:
I guess for ATO training you have concession to revert to NCO?The +40% is probably UK specific (on top of Part-CAT), it’s a figure that you apply to any POH performance numbers (it’s CAA POH supplement for public transport), not sure if you have apply it to TOD or ASDR but I doubt you are getting less than 900m for CAT operations
@Ibra, did you mean +34% on take-offs and +43% on landings for Public transport?
Pink 110 local copy
Peter wrote:
Sure, but all certified piston twins are supposed to “climb” on one engine
That depends on when they were certified. And not necessarily in the take-off configuration.
arj1 wrote:
did you mean +34% on take-offs and +43% on landings for Public transport?
Interestingly, before part-NCO, Swedish authorities required +43% on landings for private ops, but +0% for takeoff…
Ibra wrote:
Yes, in typical less than 800m runways you have to reject at 30kts-40kts, after that it’s mostly a controlled crash
At Vr, V1 in GA (SEP NCO on raw POH TO data+x%) it’s outgoing only
It’s far away at least from my experience. We have 800 meters of runway on my homebase, with offset thresholds due to roads at both ends of the runway, so remaining 600 meters for landing. My personal limit for touchdown is the marking of halfway, leaving 400 meters to stop from around 60 knots. It’s not that harsh for the brakes as it may sound.
800 meters are still sufficient to realise a necessary abort of the takeoff run the “easy way”: 400 meters or halfway through the runway there should be more or less rotation speed (depending on weight and aircraft type and so on). You still have enough runway left to stop from that point. So if at halfway all looks fine it is a “go”, and if not, it’s a “stop”. This is typically done like this for anything up to Twin Comanche. If you’re heavier or worse power/weight ratio, then you’ll need a longer runway to have calculations “the easy way”.
I think my Comanche needs about 250 meters of runway for a full stop out of touchdown speed (60-65 knots). I already had to test it, and I’m not happy about it. This is with full brakes.
Well let’s see. My most recent rejected takeoffs. A forgotten pitot tube cover in a PA28, noted at about 40-50 knots.
Next one, some really big birds (gooses I think) on a runway close to the Rhine River, which did not make any intention to vacate the runway. I’ve been aware of them. Aborted at about 40 knots, on the next takeoff run they had moved on to some field next to the runway.
Next one, two fouled spark plugs in the same cylinder. Had to wait really loooooong at holding point, at least 15 minutes, where special VFR operation was active. There was only one traffic allowed airborne in the CTR. There’s no way to “burn free” two spark plugs in the same cylinder, so I had to abort the whole flight (today I’d know what to do)..
There is a huge span of possible rejected takeoffs. I think the most important thing is to have in mind, that takeoff run will only be completed if ALL goes fine. So the mindset is to abort in practically any case if not all is fine. It’s the same mindset for an instrument landing. You are only good to land if all is fine and runway in sight. With this mindset, a rejected takeoff is a non-issue.
Rejected takeoffs get more interesting, if the TORA is less than the double necessary for the aircraft and weather conditions. It is where you have to start to calculate.
huv wrote:
with a very bad and tired engine
“Tired engines” are not necessarily low on power. Misadjustments, airflow blockings, and valve train wear are the main causes of low power on ContiLycosauruses (add turbo and control if turboed, but that is evident in MP indication), irrespective of tiredness and age.
172driver wrote:
Good luck with that, most of the light MEPs have very, shall we call it anemic, climb performance on one engine. Depending on DA that ‘performance’ may in fact be a negative value
Exactly, and they are only required to climb with dead-engine feathered and gear up…at the right speed and level of sideslip…
I thought they were only required to keep their heading during an engine failure, not climb.
Peter wrote:
I am surprised one would reject takeoffs on a twin that readily. They are after all supposed to take off and fly on one engine – subject to the required speed having been achieved.
Take off on one? That may be the case in jets, but not in a light twin, the performance is generally not that good.
In a jet the decision making is clear and logical; above V1 you continue, below you abort.
V1 can occur while you are still on the runway, it matters not, the decision is the same.
All the piston twins and turboprops I have flown do not really have such an option. Until one is established in the climb all bets are off and I have been taught to treat them like a single by closing both throttles, not that it’s ever happened to me outside of a training scenario..
Most light MEPs will climb at MTOW on one engine, clean. Of course DA affect the climb rate. But one of the worst the Piper Apache at ISA and MSL will climb at about 150ft per min.
A Twinkie may be a little better, a DA42 or PA44 will perhaps climb at 200fpm. As you get more powerful so the climb rate usually gets a bit better rising to some twins where it is a non entity. One of main problems is keeping the speed above Vmca, which is why many pilots delay Vr until the aircraft is above Vmca.
Take off on one? That may be the case in jets, but not in a light twin, the performance is generally not that good.
We must have wires crossed, and my twin expertise is nil (1.5hrs on a 421C, against 2700+hrs in SEP 
) but surely that is what this bible on MEP EFATO thread and particularly here discusses
If a twin is supposed to crash upon an engine failure (assuming a balanced runway, which I accept most piston GA does not comply with, of necessity) then all the various numbers like V1 and Vmca are meaningless.
which is why many pilots delay Vr until the aircraft is above Vmca.
Exactly.
