Engine out practice

[Keith Simmons]

I am keen to build a electric twin and in the future, 4 engines.

4 engines is easier if one happens to fail, but I am sure it would be sensible to practice an engine out on a twin by switching off power to an engine from a safe height & speed and switch on the 'dead' engine if getting out of control. A buddy box if you want more security if things go south.

Full size, pilots practice on simulators and (in the air in multi engine trainers?)

Has this been done or do we find out if we can cope when it actually happens with models?

Keith

[Phil 9]

I have not heard of this for a model before. With a good electric setup a single motor failure would be an unlikely occurrence one would have thought.

I often thought if a rudder gyro might help a twin in the event of an engine out.

Any ideas of what models you will build?

[Martin Harris - Moderator]

I used to do it regularly on my Slim Twin - but it's possibly the easiest non-coaxial twin to handle with closely spaced engines and twin fins/rudders in the slipstream of both engines. I lost an engine on the maiden (and my first twin flight) and found it quite easy to balance out with rudder.

So the answer is really that it would depend on the type of model you're using - some can be rather unforgiving. My usual advice is to treat an engine out as a deadstick - close the throttle (and don't be tempted to use it again) as soon as you lose an engine unless you're very familiar with its single engine behaviour.

[Martin Harris - Moderator]

Posted by Phil 9 on 28/07/2016 13:20:34:

With a good electric setup a single motor failure would be an unlikely occurrence one would have thought.

But not unknown. I lost my Nijhuis Mosquito on its maiden due to a motor shaft failure (ignored my advice above and stupidly opened the throttle when I was getting too close to a hedge). Some years ago I watched a Hornet flick into the ground instantaneously when one prop left the motor on a fast pass (owned/flown by a meticulous owner with experience of immensely powerful electric set-ups) - and I had a dead stick the other week while flying a friend's model with dozens of flights under its belt...on landing, all control was lost due to the main battery wires unsoldering themselves from the (well within spec) melting ESC/BEC - a very lucky model!

[Peter Miller]

Now my Grumpy Tigercub with two ic engines is a little dream.You hardly notice when one engines goes out. Probably the best twin engined trainer going.

[Keith Simmons]

The Article on the home page of flying technique:what goes up... Got me started when reading multi engined models and what happens if it goes wrong?

I find that it's best to experience and practice controlling the model so you then know what's possible and not panic when it does happen. Be forewarned in my view.

I would love to build an Avro Manchester and I understand that single engine out happens too often due to the unreliable Vulture engines. (It was delimited in power as the cooling fluid or lubricant was not effective enough) Having 3 fins as an earlier mk1 and maybe two fins and a larger tail plane as a mk1A if I don't get enough yaw control. (I think the majority crashed as the remaining engine was overtaxed, causing it also to fail)

[MattyB]

Posted by Keith Simmons on 28/07/2016 12:56:38:

I am keen to build a electric twin and in the future, 4 engines.

4 engines is easier if one happens to fail, but I am sure it would be sensible to practice an engine out on a twin by switching off power to an engine from a safe height & speed and switch on the 'dead' engine if getting out of control. A buddy box if you want more security if things go south.

Full size, pilots practice on simulators and (in the air in multi engine trainers?)

Has this been done or do we find out if we can cope when it actually happens with models?

With an OpenTX based transmitter like the Taranis it would be pretty easy to setup an "engine out" simulator - click the momentary and it takes out one or other of the motors at random, but if you advance throttle to full it automatically powers up the dead engine. You could do the same with a Jeti too I'm sure, but more mainstream TXs without logical switches are likely to struggle.

[Mike T]

I managed it (sort of) on my 388! One throttle (esc) channel was mixed to a rotary control knob, primarily to trim-out the inconsistencies between esc's so that throttle response was linear. It had a side benefit in that said knob could be fully wound back to close down one motor. Installed in a Twinstar II, it was useful for single engined practice. (It became superfluous as one motor always quit before the other anyway!)

[Tony Cook]

I, like Mr Miller, enjoy oil burner twins..on one of my early models, I had the misfortune of an 'engine out' and needed power to maintain height, the model flick rolled and I lost the plane. Since then I've learnt to open the throttle slowly to feel what's happening and use the rudder. Over and above this I've set a 'throttle cut' for both engines using a mix on one of the auxiliary switches and then just glide. Used it twice and works a treat when all else fails. I'm sure you could do the same with electric. Multi-engines really have great sound & presence!

[Paul Marsh]

This is good for engine out - can keep flying with just one engine...even take off and fly on one, if you've got a concrete runway.

[Martin Harris - Moderator]

Posted by MattyB on 28/07/2016 18:37:59:

With an OpenTX based transmitter like the Taranis it would be pretty easy to setup an "engine out" simulator - click the momentary and it takes out one or other of the motors at random, but if you advance throttle to full it automatically powers up the dead engine. You could do the same with a Jeti too I'm sure, but more mainstream TXs without logical switches are likely to struggle.

I don't recall the details, but I was using an FF9 at the time so any reasonably capable transmitter should be able to do it with mixes and a little imagination.

[MattyB]

Yes, any mid range or above TX should be able to run dual throttle setups so with a few free mixes you can setup the ability to shut one motor down. Making it a random motor that cuts to add additional realism though I somehow doubt; for that you need a way to create an oscillating signal and use that as a feed to logical switches that trigger the throttle mix on a latch.

Edited By MattyB on 29/07/2016 00:29:29

[Martin Harris - Moderator]

Sorry, you're quite right Matty - I was guilty of speed reading and thinking more of the original requirement to be able to shut an engine down to idle selectively.

[MattyB]

That would still be of some value to learn how to handle the model with one motor out, but for me the crucial bit is really getting used to quickly identifying it's happened, and which one it is. Any delay in doing that or diagnosing that the wrong engine has been shut down could be a catastrophe, hence the need for the practice shutdown to (ideally) be random.

Edited By MattyB on 29/07/2016 09:42:55

[Keith Simmons]

Thanks Matty, maybe learning to handle the model with one motor is to me the first step down that path and once you have identified how much power needed for level flight, that to me is the benchmark to what you can fall back on. Next is random practice shut down first on level flight and then at any time during the flying session.

After all the solders practice drill so often that when it does happen, the solders react without thinking.

This to me is useful as if anything does happen unexpectly, you react quickly and give yourself a bit more time to see if you can recover the model safely and in one piece.

Can you set up this with the ESC per motor? Looks more tricky to add the random motor cut-off?

Keith

[The Wright Stuff]

Maybe just get someone else to assign the switch to one or other engine before the flight, without telling you which one. Then you hit the switch to kill one, but you yourself don't know which one will shut down!

[Keith Simmons]

That's doable and me on a buddy box to happen unexpectly. Feel safer with that and the above is a good idea but then you are prepared when you hit the switch.

Brings me to a time when the instructor releases the tow cable early and other tricks when learning to fly gliders. Happy days.

[David perry 1]

Keeping control of a twin with OEO is hard enough full size! In fact, on most non-perf A twins the BEST option in engine failure for MOST non-professional (i.e. well rehearsed) pilots is to quickly close the other engine and land dead stick.

On an electric model I should think a sensing circuit that closes the live engine when sensing a dead one is the best option. Fit a gyro in the rudder to keep the model safe for a few seconds until the sensor kills the second motor, then glide to land safely.

The problem with engine failures is not that they are unflyable it's that they always take you by surprise! If you survive the shock then its a balancing act between enough rudder and aileron to keep the model straight, then balancing throttle against the now enormous drag - recall that when losing one of two engines you have not lost 50 percent power but more like 60 to 75 percent power because of drag. Aye, it's fun

David

[Martin Harris - Moderator]

I loved the advice that I once heard - that in the event of an engine failure in a twin, the purpose of the other engine is to fly you to the scene of the crash!

[Keith Simmons]

I will add a gyro to help out on multi's. Thanks.

Having a gyro to kick in helps as a few seconds pass before you take action as you observe the flying behaviour of the model, while as a full size you react quicker as you are in the aircraft.

Perhaps to reduce the power on a good engine as well to help the gyro but that may confuse as it will mask what's going on?

On a SR-71 Blackbird, the gyro kicks in so quickly that the pilot feels rapid deceleration but has no idea which side is effected and looks at his instruments to find out. At air shows the blackbird often does a pass with one engine on idle and the other on increased power. (Full afterburner?) The Blackbird is always on afterburner when it flies on missions.

But on a Foxbat, a loss of an engine results in a loss of the aircraft as it yaws to destruction at high speed and the pilot has to eject.

Keith

Edited By Keith Simmons on 30/07/2016 09:09:58

[MattyB]

Posted by Keith Simmons on 29/07/2016 10:07:02:

Thanks Matty, maybe learning to handle the model with one motor is to me the first step down that path and once you have identified how much power needed for level flight, that to me is the benchmark to what you can fall back on. Next is random practice shut down first on level flight and then at any time during the flying session.

After all the solders practice drill so often that when it does happen, the solders react without thinking.

This to me is useful as if anything does happen unexpectly, you react quickly and give yourself a bit more time to see if you can recover the model safely and in one piece.

Can you set up this with the ESC per motor? Looks more tricky to add the random motor cut-off?

Yes, shouldn't be an issue. I don't have an electric twin at present, but may still set this up using OpenTX Companion S an experiment. When I get it working I will post the eepe to RCSettings.

Edited By MattyB on 30/07/2016 10:17:52