Shake, rattle and roll

Julian Bone · Post by **Julian Bone** » Wed Jul 09, 2008 7:03 pm

a wax cylinder and a needle would probably work quite well or try drawing a circle on a piece of paper
to reduce vibration just cut off mixture to engine

Richard Mole · Post by **Richard Mole** » Thu Sep 25, 2008 8:40 pm

I have just seen from his website that my good friend Mark Langford has discovered a 'low cost' propeller balancer - see http://home.hiwaay.net/~langford/dynavibe/
Its obviously not a general tool for assessing 'ride quality' but its moving in that general direction.

Captain Pulsar · Post by **Captain Pulsar** » Wed Oct 01, 2008 10:17 am

Probably a silly suggestion, but I've noticed during descent that the fluid in my compass (which needs topping up) provides an elaborate surface pattern that would appear to be correlated to cockpit vibration. During descent the trusty rotax has the occasional miss when not under load and I have noticed a huge spike appear in the surface behaviour of the compass fluid that coincides with the pulse felt through the structure.

I wonder if this might be exploited whereby a simple calibrated tube of compass fluid rigidly mounted to the coaming might provide a visual picture of the vibration encountered and perhaps might be calibrated with small increments to measure the amplitude of the spikes observed on the surface of the fluid.

Ok its probably daft, but it got me to thinking, at least it would be cheap!!

Richard Mole · Post by **Richard Mole** » Wed Oct 01, 2008 1:01 pm

Its probably one of those clever observations that you could use to modify the operation of the a/c so as to avoid the spikes as much as possible, with a view to giving the rotating masses a longer fatigue life or whatever.

It reminds me of that US guy, Bob (Hoover?) was it, who used to loop a twin with the engines out and with a glass of water resting on top of the panel to encourage him to fly smoothly! If I think that my own flying has got a bit physical (!) I imagine a glass - or should it be tumbler - of water in the cockpit as a device to encourage smoother control inputs.

Pete · Post by **Pete** » Thu Oct 09, 2008 4:34 pm

It was actually my compass revolving at about 5 RPM that convinced me to throw away my old prop.

Marvelous things compasses - occasionally use it when flying too.