Bolly Prop

[Bruce Tuncks]

Anybody know about the Bolly prop shown on their ad with a Jabiru?

 

I wonder how it can work, but they say its for a direct-drive engine. There was a trial of a previous Bolly prop on a Jabiru in SA which ended with a blade being thrown off, so I'm sure this new one is different........

 

Bruce

 

 

[Guest brentc]

I saw this too and wondered the same for the exact same reasons.

 

I question the offering given that the company is now under new management.

 

There are of course other carbon props available for Jabiru engines so I'm thinking that they must have modified their model to be similar. As a side note, my carbon prop is solid which not all of them are.

 

 

[jetjr]

I think that particular Jab was next to thier stand @ Natfly, Someone I spoke to said it had only been running for a short time.

 

Real thing they are working on is inflight adjustable for the Jabiru - expected to be around $6K

 

JR

 

 

[Guest jabiru]

Phone call from Bolly!

 

Well boys only this week I had a phone call from Peter, from Bolly in regard the new Jabiru propeller !! they had just returned from Bundaberg after extensive testing with the Jabiru factory,and now further testing at a Queensland university that has the capacity to give it the ten tonn test, and all is looking very good and a report is being drawn up to give to Rod.S shortly,the cost of the two blade propeller with variable ground pitch is around the $1,800,they are also working very hard to have the GA propeller for the Bundaberg Airshow.I am Looking forward with great anticipation to reading and hearing more reports on the this new propeller for my SK Jabiru before my decision is made.

 

 

 

Regards Shaun.

 

 

[Guest Orion]

"I question the offering given that the company is now under new management."

 

Hi BrentC

 

What has a management change got to do with it ?

 

Have i missed something ?

 

Cheers

 

Kent

 

 

[Guest brentc]

Put it this way Kent. The previous management was working on a carbon prop for the Jabiru. It shed a blade and the aircraft (and possibly pilot) were nearly lost (the engine was almost ripped from its' mounts) Then a message was posted on their website to the effect that there would be no further development of Bolly props for Jabiru engines.

 

I then note that they are under new management (presumably new owners) and now a Jabiru prop is back on the cards.

 

Just an observation as you would hope that something major has been changed in the propellor design before you would want to purchase one.

 

My prop has supposedly been tested to 50 tonnes, so I wonder if the Bolly is hollow or solid? Any idea Shaun?

 

 

[Tomo]

I overheard Steve Bell (Raa Tech Manager) talking something about Bolly and Brolga props... something about he's been working with one of them and got them producing again....

 

I'm not sure about any of that, but If you give Steve a buz he'll soon let you know I'm sure...

 

 

[Guest Orion]

Hi BrentC

 

Thanks for the background info.

 

Maybe new management means fresh ideas and approach.

 

cheers

 

kent

 

 

[Guest jabiru]

Solid Prop!!!

 

Brent

 

 

 

Yes Peter did say that the new prop is a all new Solid Prop,and it is also not the Series five, as per the advertisement on the Bolly prop web site,this is a totally new propeller designed specifically for the Jabiru engine.

 

 

[Bruce Tuncks]

I have the idea that the light wood prop is easy on the crankshaft, so a more rigid prop may have some rubber in the hub to absorb some of the pulsation of a direct drive.

 

Bruce

 

 

[Modest Pilot]

The hub of the prop is solid composite as are the blades. Rod told me that Jabiru would consider approving it for some applications pending successful testing. The hard part here (stress gauges etc. are costly) is the vibration testing for the 10 or so primary modes of vibrations. I’ve flown in my mates J250 with his nice looking new 3 bladed Petronius (spelling?) prop. Very smooth but the vibrations are quite different, less vibration than the approved wooden props and much higher frequency. It’s the harmonics that worry me; what happens if they build up on say an engine frequency; remember the Lockheed Electras; it tore the wing off!

 

I think I’ll stick to approved props or ones tested by very high time in service in futurensider aproving it for some apllications pending

 

 

[facthunter]

prop vibration harmonics

 

You are right to be concerned about the damage of torsional vibrations, with engine/ prop combinations, but in the interests of historical accuracy, the shedding of the Lockheed Electra L-188 wings was from another cause. Deformation of the engine mounts altered the thrust line of the prop and a wing twisting aerolastic situation (another harmonic) occurred at a critical airspeed and almost instantly took the wing off.

 

The propellers which were of fabricated alloy steel, did suffer from extensive cracking which was detected by low frequency vibration meters, When a particular level of vibration was detected the engine was shut down. However that is not connected with the wing problem.

 

.........I think about 4 aircraft were lost with the wing problem, and it remained a mystery as to what was happening, till one was observed from another aircraft. Nev

 

 

[Guest pelorus32]

[snip] As a side note, my carbon prop is solid which not all of them are.

G'day Brent,

 

which prop is that?

 

Regards

 

Mike

 

 

[Modest Pilot]

Quiet right Nev, I was on L188s at the time. It was actually the cracked engine mount that started the harmonic that took the wing off, there was also the runaway prop problem to get your attention! In fact sounds mad but you actually pushed the throttle full forward to engage the prop locks. All a bit to long on details to explain; but the point was that there was no warning to the pilot until it happened. The lesson I think is if you change anything that changes prop, engine, airframe relationships be very very carefull!

 

 

[Guest brentc]

G'day Brent,which prop is that?

 

Regards

 

Mike

It's the Revolution, made in Bundaberg by former Jab timber prop manufacturer. Whilst it's not approved for factory built models I'm of the belief that an agreement between manufacturer and Jabiru was a bee's knee away but fell through.

 

I'm still not too sure about the carbon hub. Aside from perhaps a kilo or two I'm not sure on what the advantages are.

 

I'm also told that the Sensinich was approved due to the manufacturer providing resonance information to Jabiru.