Propeller installation

[compsci]

I have replaced the Senswitch wood propeller on my U.S. J230

 

with another Senswitch wood propeller. I have been told that

 

JABIRU Australia suggest installing the propeller 60 degrees

 

off from the manufacturer's instructions. Does anyone know this to be

 

true and if so why?

 

Compsci

 

 

[Modest Pilot]

I guess I'm lucky having access to a dynamic prop balancing rig.

 

It doesn't seem to make a difference how you bolt it on, so I settled on a spot that stops the prop horizontal (most of the time) on shutdown!

 

 

[Guest Qwerty]

I have replaced the Senswitch wood propeller on my U.S. J230with another Senswitch wood propeller. I have been told that

JABIRU Australia suggest installing the propeller 60 degrees

 

off from the manufacturer's instructions. Does anyone know this to be

 

true and if so why?

 

Compsci

What are the manufacturers recommendations. 60 deg from what???? I'm with Modest, My a/c is a tail wheel and I like the prop horizontal.

 

 

[compsci]

What are the manufacturers recommendations. 60 deg from what???? I'm with Modest, My a/c is a tail wheel and I like the prop horizontal.

Senswhich installation instructions are

 

1. Position piston in cylinder one at the top of the cylinder.

 

2. Install prop at 10:00 and 4:00 o'clock.

 

The prop stops at random positions.

 

 

[Guest Qwerty]

Thanks Compsci, do they say why the prop needs to be installed to these specs? This is all completely new to me. I don't undertsand their thinking.

 

 

[compsci]

Thanks Compsci, do they say why the prop needs to be installed to these specs? This is all completely new to me. I don't undertsand their thinking.

They say....it allows for easier hand propping.

 

 

[facthunter]

Prop. position.

 

A six cylinder has the chance of stopping in 3 positions (If it is responding to compression pressure), So why would it matter. That gives a pretty random outcome, anyhow.

 

As has been said, the Jabiru motor with standard ignition systems , cannot be propswung. You can test the compressions by pulling the motor through, so for standardisation of "feel" you might go for a uniform position, for that reason

 

A four cylinder motor has the compressions at 180 degrees so (If it is not geared) you could achieve an outcome. The few 4 cyl motors that I am familiar with in GA aircraft are set up in a specific position and I would relate that to the suitability of the position for propswinging.

 

Incidently I would NEVER move a prop to any position with a conventional GA motor without extreme care, as the "Impulse" on the magneto gives a sensational spark at zero revs, when it goes "click" This only happens in the forward direction. Some engines should not be turned in the reverse direction, (the ones fitted with vacuum pumps), also.

 

Are we talking about Sensenich props here, or is there another new brand that I don't know about out there? Nev

 

 

[compsci]

It is a Sensenich. I miss-spelled the name of the propeller manufacturer.

 

 

[facthunter]

Sorry.

 

I wasn't trying to embarass you, Sometimes new close-sounding names appear. They (Sensenich), are a very old manufacturer of wood and now composite props. Original equipment on a lot of famous aircraft.. Nev

 

 

[compsci]

That's OK...read what Qwerty (above) called me.

 

 

[Bruce Tuncks]

prop position

 

If you had a dynamic prop balancer, there would be a position where the total system vibration was less, you would have to find it by trial and error.

 

I'd be interested to hear from anyone who has had a dynamic balance done on an older Jab, the type with no spinner backplate.

 

Bruce

 

 

[Guest Qwerty]

That's OK...read what Qwerty (above) called me.

Sorry mate, I wasn't referring to you. I get a bit short on for patience with the seeming endless stupidity from "Gen Y" and particularly Gen Y from the USA with their "go figure", "whatever" and other repedative, brainless retorts.

 

Your question re prop orientation is something that I am actually very interested in. On another thread, I have started a similar discussion re horizontal prop parking orientation supposedly due to moisture movement.

 

 

[compsci]

Qwerty,

 

In what Jabiru document does it state that the J230 (or 3300 engine)

 

is not to be hand propped?

 

Compsci

 

 

[Guest Qwerty]

Its not prohibited, the problem is that the 3300 ingition is a coil type rather than a magnito, fine distinction I know but the difference is that the coils will not (legal disclaimer here, in most cases) fire under about 300 RPM which is above the speed that you can throw the prop. Its a pitty not to have the option to hand start. A few years ago, I did a trip half the length of the country (Oz) in a C177, the starter crapped its self after the first leg. We simlpy kept flying (for the next two weeks) hand starting it. They hand start well, for safety you really need two people (preferably two pilots) though.