Handstarting the Douglas B-19 - Aircraft of World War II

Graeme · 05-23-2009, 06:58 AM

Found this in an old magazine today. Caption reads...

Quote:

The B-19 represented old technology in many ways. Its giant 17 ft diameter propellers had to be turned by hand, prior to engine start.

Looks like rope burn waiting to happen. Centripetal force removed the ropes once started? Did any warplane engines of WWII have to be hand started?

HoHun · 05-23-2009, 08:15 AM

Hi Graeme,

>Did any warplane engines of WWII have to be hand started?

I don't believe any of the powerful engines were hand-started, if you discount devices like the DB 601's hand-cranked inertia starter.

Note that the quote doesn't actually mention hand-starting, but merely turning the propeller. This appears to have been standard operating procedure, mainly to ensure that there was no "liquid lock" present in an engine, resulting from oil seeping into the bottom cylinder, that would prevent the engine from turning (unless done with sufficient force to break something, as the stater motor could).

From what I'e read, one or two crewmen were usually enough to turn the engine, so the picture above seems a bit crowded - perhaps because everyone wants to be featured on the photograph. Enough crewmen pulling at the same time might also be able to break something ...

The practice seems to have become unnecessary only post-WW2 when the starter motors were equipped with reliable clutches to disengage them if the torque became too high. It might be that the wartime engines were thus equipped too and the operaters just lacked the trust in them while suffering no shortage in manpower - I don't know for certain.

Regards,

Henning (HoHun)

Graeme · 05-23-2009, 09:48 AM

Quote:

Originally Posted by HoHun

Note that the quote doesn't actually mention hand-starting, but merely turning the propeller.

Thanks Henning. Ignorantly I thought it was the process to start the engine.

GrauGeist · 05-23-2009, 02:06 PM

HoHun has it right, Graeme

The earlier radials needed this process performed on them as the oil would settle in the lower cylinders and hand turning would clear the oil, preventing a hydraulic lock. Later engines were designed to eliminate this condition.

It takes two people per prop to "push through" or more, depending on your time frame.

They push the "push through" 9 times or three times per prop on the three bladed engines. They start on the outboard engine on the right wing, moving to the inboard engine, then the inboard on the left wing, then on to the last engine.

When the engine has been rotated, the prop is positioned with one blade at the 12 O'clock position and an engine that is waiting to be rotated has a prop facing to the 6 O'clock position. The photo shows #1 engine in the position indicating it hasn't been rotated yet, and barely visable are the bottom of the props on the right wing showing they have been rotated already.

A tall bomber would have to have a rope gang to turn the props since the guys aren't tall enough to physically push the blades, like on a B-17 for example.

FLYBOYJ · 05-23-2009, 03:32 PM

Usually to remove liquid lock, one would pull a few sparkplugs on the lower cylinders. If not removed it would bend connecting rods. T-28s have a set up to remove the excess oil build up.

wheelsup_cavu · 05-23-2009, 04:23 PM

There are several videos showing this procedure being done.
Of course I can't find one right now when I want it.

I never knew the reason why they were doing it.
Another tidbit of information for my files.
Thanks.

Wheelsup

05-23-2009, 02:06 PM	#4
GrauGeist Senior Member Join Date: Aug 2008 Location: Redding, California Posts: 3,346	HoHun has it right, Graeme The earlier radials needed this process performed on them as the oil would settle in the lower cylinders and hand turning would clear the oil, preventing a hydraulic lock. Later engines were designed to eliminate this condition. It takes two people per prop to "push through" or more, depending on your time frame. They push the "push through" 9 times or three times per prop on the three bladed engines. They start on the outboard engine on the right wing, moving to the inboard engine, then the inboard on the left wing, then on to the last engine. When the engine has been rotated, the prop is positioned with one blade at the 12 O'clock position and an engine that is waiting to be rotated has a prop facing to the 6 O'clock position. The photo shows #1 engine in the position indicating it hasn't been rotated yet, and barely visable are the bottom of the props on the right wing showing they have been rotated already. A tall bomber would have to have a rope gang to turn the props since the guys aren't tall enough to physically push the blades, like on a B-17 for example. __________________ "Look back over the past, with its changing empires that rose and fell, and you can foresee the future." - Marcus Aurelius, Emperor of Rome > I Support Doug Gillis <

05-23-2009, 03:32 PM	#5
FLYBOYJ IP/Mech THE GREAT GAZOO Join Date: Apr 2005 Location: Colorado, USA Posts: 16,049	Usually to remove liquid lock, one would pull a few sparkplugs on the lower cylinders. If not removed it would bend connecting rods. T-28s have a set up to remove the excess oil build up. __________________ "IF ITS RED OR DUSTY, DON'T TOUCH IT"

05-23-2009, 04:23 PM	#6
wheelsup_cavu Senior Member Join Date: Mar 2009 Location: Corona, California Posts: 1,534	There are several videos showing this procedure being done. Of course I can't find one right now when I want it. I never knew the reason why they were doing it. Another tidbit of information for my files. Thanks. Wheelsup __________________ Cheers Wheelsup_cavu Wheels's Photos - Time lapse build of an F/A-18 Super Hornet - Lock N' Load

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05-23-2009, 08:15 AM	#2
HoHun Senior Member Join Date: Oct 2006 Posts: 1,765	Hi Graeme, >Did any warplane engines of WWII have to be hand started? I don't believe any of the powerful engines were hand-started, if you discount devices like the DB 601's hand-cranked inertia starter. Note that the quote doesn't actually mention hand-starting, but merely turning the propeller. This appears to have been standard operating procedure, mainly to ensure that there was no "liquid lock" present in an engine, resulting from oil seeping into the bottom cylinder, that would prevent the engine from turning (unless done with sufficient force to break something, as the stater motor could). From what I'e read, one or two crewmen were usually enough to turn the engine, so the picture above seems a bit crowded - perhaps because everyone wants to be featured on the photograph. Enough crewmen pulling at the same time might also be able to break something ... The practice seems to have become unnecessary only post-WW2 when the starter motors were equipped with reliable clutches to disengage them if the torque became too high. It might be that the wartime engines were thus equipped too and the operaters just lacked the trust in them while suffering no shortage in manpower - I don't know for certain. Regards, Henning (HoHun)