Why park a timber prop horizontal?

[facthunter]

Pushing Areas.

 

There are plenty of places on an aircraft that you would not apply much force to. I have always used the prop (Near the hub) as a suitable place to push the aircraft. The engine mounts and where the U/C is mounted are the strongest parts of a light aircraft. Where else would you push a Jab if you are on your own and don't have a jigger to attach to the nose/ tailwheel. Nev

 

 

[Guest Qwerty]

Sorry to disagree Qwerty,Paint will not seal out moisture

 

Lots of other proprietry 'sealants' also will not seal out moisture.

 

Paint and other like sealants are permeable and allow the substrate to "breathe" this means allows moisture in and out in the right atmospheric circumstances.

 

Our own Skin will keep out rain but it is permeable

 

Dont let the paint ads on TV fool you.

No disagreement Skydog, sealed is sealed and painted is painted.

 

Dont get me started about TV. They say "the news is next" and the next thing you see is a bloody ad.

 

And how about "the end of the decade" Idiots. A decade will end 10 years after it starts, so the end of the decade that started on 29/12/1999 ended yesterday.

 

If they (idiots on TV and radio) are talking about the end of the 199th decade of the calander, that certainly occours in 365 days time.

 

 

[Captain]

Qwerty

 

Below is excerpt from the Jabiru 3300 manual. As an engine, airframe and prop manufacturere surely they must have detected some out-of-balance from vertical storage to use such wording:

 

Quote

 

Leave the propeller in the horizontal position to ensure even distribution of liquids in the wood. If left in the vertical position, liquids will drain to the lower tip resulting in an unbalanced propeller.

 

 

 

Unquote

 

 

 

 

 

 

 

Hope this helps.

 

 

 

 

 

Geoff

 

 

[turboplanner]

If they (idiots on TV and radio) are talking about the end of the 199th decade of the calander, that certainly occours in 365 days time.

OK Qwerty, you've sucked me in. What's this about the 199th decade of the Calendar - are you working on the Mayan Calendar?

 

Captain, why do Jabiru insist on following Tiger Moth technology? Why not one of the more modern materials? When I look at photos of parked Jabs, there must be a lot of out of balance props out there.

 

 

[Guest Qwerty]

Turbo,

 

I'm talking about our calendar, Georgian or Roman or what ever the hell it is.

 

The end of 2010 is the end of the 199th decade. The same way that the end of 2001 was the end of the millenium (on our calendar). I suppose I need to explain it.......

 

The first decade started at the start of year 1 and ended at the start of year eleven.

 

The second decade started at the start of year 11 and ended at the start of year twentyone.

 

it follows then that;

 

The 199th decade started at the start of year 2001 and ends at the start of year 2011.

 

Simple.

 

Thats not to say a decade didn't end last night, just not a calandar decade.

 

As for Jabiru and their park the prop horizontal, they can expect a call from me some time real soon.

 

Cheers, Qwerty

 

 

[turboplanner]

I forgot....and having to wimp it every time it rains

 

 

[Captain]

Captain, why do Jabiru insist on following Tiger Moth technology? Why not one of the more modern materials? When I look at photos of parked Jabs, there must be a lot of out of balance props out there.

G'day Tubb,

 

My guess is price and the fact that the "Tiger Moth technology" works OK.

 

Although surely timber props have a good place in this Recreational Aviation caper, and it seems to me that they are heaps of happy Jabiru prop users. After all, all this thread was discussing is which way to park them.

 

But any Jab owner who has gone to a Sensenich (and I am one of 'em) will tell you how much better they are, although at a reasonable increase in dollars.

 

Looks like some of these posts are hotting up a bit in 2010.

 

Regards Geoff

 

 

[BigPete]

I too, :thumb_up: am a propellor puller - what more can I say? :big_grin::big_grin::big_grin:

 

regards

 

i_dunno

 

 

[Guest Qwerty]

...... why do Jabiru insist on following Tiger Moth technology? Why not one of the more modern materials? ..........

Tubo, timber has a lot to recommend it.

 

Its cheap

 

Its easy to work

 

Its stronger than metal

 

It does not fatigue, an important property for a prop.

 

It has better fire resistance than metal (and probably FRPs but I'm not sure about that)

 

It has better resonance qualities than metals (in a/c applications)

 

Here are a few touchy feely reasons for you too

 

It is from a renewable resource

 

It is a Carbon positive (rather than a significant Carbon cost to produce)

 

It is non toxic (other than for blackwood and thats only used in furniture anyway)

 

 

[BigPete]

AND (this is a biggie)

 

it absorbs a hell of a lot of energy if you have a prop strike.

 

regards

 

PS - it's also cheaper to maintain and refurbish.

 

 

[Guest ozzie]

Plus a timber prop is pretty easy to make yourself.

 

 

[RKW]

The end of 2010 is the end of the 199th decade. The same way that the end of 2001 was the end of the millenium (on our calendar). I suppose I need to explain it.......

 

Hi Qwerty, I think you are on the right track, but wouldn't the end of 2000 be the end of the second millenium. First millenium I thought would be year 1 to 1000, second millenium year 1001 to 2000 etc... please correct me if I'm barking up the wrong tree. Best Regards, Bob

 

 

[turboplanner]

Only if you were a Christian. I read recently that the US only switched to the Gregorian Calendar in 1975, and there were other versions along the way so we may be in 2010 or we may not.

 

There are ancient civilizations dating back as far as 20,000 years who accurately calculated dates from the stars, the Mayans being just one group.

 

 

[Guest ozzie]

Only if you were a Christian. I read recently that the US only switched to the Gregorian Calendar in 1975, and there were other versions along the way so we may be in 2010 or we may not.There are ancient civilizations dating back as far as 20,000 years who accurately calculated dates from the stars, the Mayans being just one group.

does this affect the ageing of the timber

 

 

[turboplanner]

Only during a Leap Year.

 

 

[Guest Andys@coffs]

....But any Jab owner who has gone to a Sensenich (and I am one of 'em) will tell you how much better they are, although at a reasonable increase in dollars....

Geoff,

 

Are you using the wood or the composite Sensenich and when you say its better, in what way(s) are they better?

 

I ask in that my original jab prop sustained some minor delamination damage due rain recently and I have to do something which is one of:-

 

1) new prop ($1050 plus GST I think, plus freight, or the time and cost for me to fly up there)

 

2) rework of the leading edge (about $280 plush freight in 2 directions, or the time and cost to fly up and stay the time it takes to rework)

 

3) Sensenich wood

 

4) Sensenich composite

 

5) Other composites, Brent has one....btw no post from him for some time... anyone seen or heard from him for a while?

 

Andy

 

 

[turboplanner]

You'll probably find him over on pprune

 

 

[Captain]

Geoff,Are you using the wood or the composite Sensenich and when you say its better, in what way(s) are they better?

 

I ask in that my original jab prop sustained some minor delamination damage due rain recently and I have to do something which is one of:-

 

1) new prop ($1050 plus GST I think, plus freight, or the time and cost for me to fly up there)

 

2) rework of the leading edge (about $280 plush freight in 2 directions, or the time and cost to fly up and stay the time it takes to rework)

 

3) Sensenich wood

 

4) Sensenich composite

 

5) Other composites, Brent has one....btw no post from him for some time... anyone seen or heard from him for a while?

 

Andy

G'day Andy,

 

I went for the Sensenich ground adjustable carbon fibre unit, purchased direct from Sensenich USA after many email exchanges with them ...... and with a Cummins spinner.

 

Sensenich were extremely helpful and communicative.

 

My conclusion is that the blade shape must be more efficient as, after a few test flights to adjust it to optimum, it appears to accelerate better and also gives 2 or 3 knots better cruise at same revs .......... and it is much smoother.

 

I previously flew Wally Rudin's 230 with a Sensenich timber prop and it was very well balanced.

 

PM me if you would like further background on why I went carbon fibre and prices etc and PM me your email address if you would like to see some pics.

 

Regards Geoff

 

 

[jetjr]

Off topic BUT

 

Im just getting a new prop for J200 and have researched this a far bit recently

 

Some options are

 

Wood

 

Jabiru - QA had better improved since the last one I bought and had to be replaced.

 

Sensinich - good long track record, actually 2 options here, from Jabiru I think are uncoated so nearly raw timber, Direct from maker can have coating which adds to resilince and waterproofing. Factory sometimes does special pricing which makes them better value.

 

Carbon Fibre - cant be fitted to LSA AC ie J230

 

Sensinich - 2 Blade, dont know much and quite expensive for 2B, should be good though.

 

Bolly - 2 and 3, probably OK but have had a few problems, someone else can run them for a while first, good local support.

 

Petrony (Revoloution Bundy) - 3B, wont answer his phone, but good value I think.

 

Duc/Helice - 2 and 3B, looks very good, similar price, 6 yr warranty, advanced materials and manufacture, supported well from NZ, recommended highly from users AND thier opposition.

 

My new 3B Duc (as in chook not duck!) is on the way

 

 

[Guest Qwerty]

Off topic BUTIm just getting a new prop for J200 and have researched this a far bit recently

Some options are

 

Wood

 

Jabiru - QA had better improved since the last one I bought and had to be replaced.

 

Sensinich - good long track record, actually 2 options here, from Jabiru I think are uncoated so nearly raw timber, Direct from maker can have coating which adds to resilince and waterproofing. Factory sometimes does special pricing which makes them better value.

 

Carbon Fibre - cant be fitted to LSA AC ie J230

 

Sensinich - 2 Blade, dont know much and quite expensive for 2B, should be good though.

 

Bolly - 2 and 3, probably OK but have had a few problems, someone else can run them for a while first, good local support.

 

Petrony (Revoloution Bundy) - 3B, wont answer his phone, but good value I think.

 

Duc/Helice - 2 and 3B, looks very good, similar price, 6 yr warranty, advanced materials and manufacture, supported well from NZ, recommended highly from users AND thier opposition.

 

My new 3B Duc (as in chook not duck!) is on the way

Also consider Richard Sweetapple in Bris and Wayne Holden in Lightening Ridge (ex Mick Dye's business)

 

I recently had a 60" x 48"/49" with a urethane leading edge made by Richard, it is an excellent prop, its accelerates better than the Jab prop. It also flies OK in the rain. the long grass on a few of the strips thatI have used has removed some paint but I am very happy with my fatigue proof prop.

 

 

[Guest Maj Millard]

I'll always park a wood prop Horizontal, and have for years. If you have used a wood prop, especially a sizeable one, and not left it parked horizontal, you will sometimes feel a little vibration on start-up.

 

If the finest Synthetic oil is Hydroscopic, and will absorb water, so will a wood or composit prop blade, especially one with a bit of unsealed wear on the leading edge.

 

If you can achieve final balance with a fine layer of paint at the tip, a few grams of moisture unevenly distributed will make a difference.

 

I think the safest way to leave a prop, from the point of view of walking into it in a semi-dark hangar is to park it at a 45 deg angle, but you just can't do it with wood.................

 

 

[Guest Qwerty]

OK Maj, so you have a timber prop with some wear on the leading edge. You park the prop horizontal and the dew settles on the left blade on the leading edge but not on the leading edge of the right blade. How is that going to keep this mythical moisture content even?

 

BTW did you read my first post, I think it was my first post where I stated my scepticism about the moisture flows down hill theory.

 

 

[Guest Andys@coffs]

Qwerty

 

recently I saanded the sealer off the end of my prop tips. On startup there was an immediate but small Towering CB that formed from the released moisture. while the engine ran rough with vibrations on startup, as soon as the cloud started to disipated so to did the vibrations. Now that Ive let the water out, I'll reseal

 

(We now return you to the mores serious programing....)

 

Andy

 

 

[turboplanner]

Warrior parked at Lightning Ridge with the prop vertical.......because I can...

 

 

 

[Guest Maj Millard]

Querty, if you look at wood under a magnafying device, it is just a series of many small cells. These cells, (when it was a tree minding it's own business in a forrest somewhere), were for amongst other things, the orderly transfer of water, upwards by the way. Wood by it's nature is designed to allow for the flow of moisture

 

For the same reason it is very important to always vacume wood after sanding, and before glueing. These little cells get filled with sawdust, but instead you want the glue to flow into them for a maximum structural glue bond.

 

If you allow your fine wood prop to get to the point where the LE has lost it's finish, and you leave it out on a dewy night, or heaven forbid fly through some light rain, your prop is going to soak it in like a sponge...it's designed to do just that.......................................