33 foot propellers? That must be one big mother of an aircraft?

[Phil Lamovie]

'Tis a Vickers Vimmy 1918 Model Bomber
2 x 454 chevy big blocks with from memory a 4:1 redux
giving about 2500 ft/lbs or about 90 mph flat stick
One section of the trip was aborted due to 100 mph
head winds !! they were flying backwards !!!

The test stand was for US certification of the redux
which was required to be "bench" tested for 30 hours.
The aircraft had to be registered somewhere and as it
was designed in England and built in Australia it seemed
only fair to register it in the country that has the most
lax aviation rules. 

The prop had to be used to "simulate" the cyclic loading on the box

The engines were mounted between the upper and lower wings
about 20 feet off the ground.

The tower was built and paid for by National Geographic
funding. (so it was free)

The size of the props was "calculated" on the predicted
available torque at rated rpm. The "engineers got it about 
25% wrong. (they guessed too low)

Net result was that the pilots used the extra (non certified)
power trying to out run a monsoon and busted a crank.

Apparently this caused " some noticeable vibration"

Regards

Phil Lamovie

Injec Racing