Cold battery

[LondonJ]

Hi guys,

Just wondering if someone could tell me whether this is as a stupid an idea as I think it is.

The battery in your plane is so cold it can't turn the engine over to start up, assuming there is no external power source can you get another (working) battery and connect it to with jump leads to the original battery or do you go home?

J

[Mark 1]

Why don't you just hand start it?

[Sensible]

Jump leads will do it just the same as for a car. Be mindful that when the engine starts that it may throw grit over the car and damage the shiny paintwork. Also, risk of the aircraft moving forward and damaging the car and aircraft if the tail hits the car when you get out of the aircraft to disconnect the car from the aircraft.

A hand swing will do the trick but it's not for the untrained or fainthearted!

[david viewing]

Jump leads will do it just the same as for a car.

Provided it's a 12v aircraft !!!

[LondonJ]

Thanks for the advice guys, I didn't know you could swing a PA28 prop but I think I'll get someone to show me how before I give that one a go.

I wouldn't have used my actual car to do it, rather a battery from a different aircraft. Anyway the sun's finally come out so with any luck it will be 6 months of warm, calm summer days.:rolleyes:

[Yorks.ppl]

I was taught that you should never fly with a battery that couldn't start the engine on the ground, reason being that whilst jump starting the battery would get the engine going it would not solve the problem with the battery that left it so flat that it could not start the engine. It would therefore possibly not re-start the engine following an engine failure in flight.

That said, those for whom hand swinging is the only way of starting the engine will probably think the above argument is nonsense. ;)

[Sensible]

The engine will turn over if the aircraft is put into a dive - providing that you have the altitude of course:\

[Yorks.ppl]

sensible, is that in a dive without use of the starter motor?

[Genghis the Engineer]

I've done this, and so far not damaged the car - but the point about not flying with a flat battery is sound.

I'd be much more inclined if in no hurry to start the car engine, connect up the jump leads, then go off for a tea and bacon sandwich. Come back in an hour, move the car, and start the aeroplane with a now (hopefully) fairly good battery.

G

[Sensible]

Yppl. starter motor unnecessary. A a propeller will "windmill" especially if the aircraft is put into a steep dive. Not sure about high performance engines since I've never tried it but it works on spam cans and motor gliders.

[DubTrub]

not for the untrained or fainthearted

Nor is diving an aircraft with a stationary prop to get the engine going.

[ShyTorque]

Not a major problem if you have the altitude to do it. The prop on the Bulldog sometimes used to stop during spins, if the spin direction was the same as the prop rotation.

Note that it's the airflow through the prop during the pitching recovery from the descent, rather than high IAS, that tends to push the motor over compression.