what_next wrote:
If you don’t lower the nose during an engine failure in a climb you will get into trouble. If you initially lower the nose during an engine failure in the cruise you lose nothing, because the little extra speed can be converted back into altitude or glide range once you are satisfied that your speed is safe. Most accidents after engine problems (especially on twins!) are caused by aircraft getting too slow and falling out of the sky. Therefore lowering the nose as an instinctive reactions seems a smart thing to do for me.
I agree instinctive reaction must be to lower nose.
Some low wing aircraft with a fuselage tank behind the engine, and above the carburetor, can maintain level on gravity feed, but not climb. A C90 engined Jodel had the engine die when climbing out of a valley. As the pilot lowered the nose, the engine picked up. After this happened a second time, he maintained level flight to his home strip. The mechanical pump lever was worn, and had slipped off. There was no electric pump fitted.
This prompted an inspection of our O200 pump at Permit renewal. For the second time in my flying career, there was a post-maintenance air leak at the fuel pump, detected by loss of power in climb with electric pump off, and fixed after a turn-back.
JasonC wrote:
I agree instinctive reaction must be to lower nose.
That depends. A tank is usually design with the pick up aft in the tank, in a special lowered department. The lowest part of the tank is therefore aft. When low on fuel, you will always get fuel when climbing, but could run out (in the small compartment) when diving, because the fuel is shifted fwd.
LeSving wrote:
That depends. A tank is usually design with the pick up aft in the tank, in a special lowered department.
That really depends and one must know one’s own aircraft in this respect. There has been a multitude of accidents and incidendts with Cessna twins (especially C310 and 340) which accidentally took of with the auxiliary tanks selected. These tanks, when not full, will expose their pick ups in any significant positive pitch attitude. A system like that would hopefully not get certified today.
LeSving wrote:
That depends. A tank is usually design with the pick up aft in the tank, in a special lowered department. The lowest part of the tank is therefore aft. When low on fuel, you will always get fuel when climbing, but could run out (in the small compartment) when diving, because the fuel is shifted fwd.
Ok, so on climb out you get an engine failure, you are going to hold the nose high (or even raise the nose) in the hope that you have a low fuel problem so the engine might restart?
Please don’t get him started.
As Jason said. Lower the nose. Then think.
Lowering the nose will lower the carb with respect to the tanks, but that is irrelevant to the reason for lowering the nose.
A few litres in a tank will have little effect on the outcome, even if raising the nose made them available.
Converting speed to height is just keeping your attention away from the problem. It was different in a WW2 fighter, with more speed and inertia.
PS The last fuel in the Jodel DR1050 rear tank is not available in the climb.
Noe wrote:
However, now that I think about it, even in flat terrain / no wind, you won’t have a circle: you can’t reach as far back as forward, as you lose non negligible time / distance / altitude / energy in the turn.
Yes, I disregarded it. You’d get the additional complication of how quickly I can turn and with what sink rate (although it’s good to know what bank angle offers a good compromise). I wouldn’t expect any such software to take that into account and Peter wrote about wind. And the fact you can’t reach as far back as forward doesn’t show the issue.
It won’t be oval anyway. Consider turning back (in no wind for the sake of argument). Say you turn 180 ° to the right and then go directly back. You’ll end up some distance (the width of the turn) to the right of the track. The analogous goes if you turn to the left. What if you want to reach a spot right on the track? You’ll have to turn more than 180 ° and you won’t be able to reach as far “down” – a sort of cleft will be created. That’s not circle nor oval nor elipse. I guess one half of it (it would be bilaterally symmetrical) might be a sort of a spiral.
JasonC wrote:
I agree instinctive reaction must be to lower nose.
For me it’s more “watch the speed.” There are situations where I’m sort of spring loaded so to speak. For example, “pushing over” is important in case a winch launch of a glider goes wrong (say the line breaks). At that point, you’re ready for it, you’re practically waiting for it to happen (and in some clubs they botch it from time to time to keep you on your toes). It won’t really surprise you unless you gave in to complacency. I probably won’t be in this mindset in cruise or cruise climb unless I feel there is little margin for error in which case I’ll have a plan ready and will be waiting to execute it. It’s like being pushed into a corner. If I feel cornered, I’ll be looking for a way out and will be ready. Also, when it comes to instinctual responses, I try to keep them in line with what helicopters need as they tend to be less forgiving. And you don’t want to push the stick (the cyclic) forward in a helicopter after engine failure (it would reduce rotor speed).
Martin wrote:
Yes, I disregarded it. You’d get the additional complication of how quickly I can turn and with what sink rate (although it’s good to know what bank angle offers a good compromise).
I have a copy of an old (1974) scientific article “The possible impossible turn” which makes a theoretical analysis of what the optimum flight profile should be if you want to turn back to the runway after an engine failure on initial climb-out. The turn itself should be done at 45° of bank at a speed 5% above stall.
That is not quite the same situation as an enroute engine failure as in the initial climb-out scenario you are aiming for a point which is known from the start (the runway), but it still gives a hint that the speed should be lower and the bank angle higher than you might first think.
JasonC wrote:
Ok, so on climb out you get an engine failure, you are going to hold the nose high (or even raise the nose) in the hope that you have a low fuel problem so the engine might restart?
No. What I mean is that if you are low on fuel and heading in a slight downward path toward an airport, the engine can easily stop due to fuel starvation, even with plenty of fuel on board. Lowering the nose further will certainly not help, but raising it, even only for a second, will.
