Propeller manufacture in OZ

[Oscar]

Thanks Oscar, I don't think that I have the skill to achieve a finish like that with a hand lay-up. I would love to see them being made.My impression is that most of the strength comes from the glass and not the hoop-pine.

Bruce, the strength comes from the wood; the glass provides some extra stiffness to limit blade twist under load, and critically, a barrier against moisture. As you know, you need to leave your prop. in the horizontal position when hangaring the aircraft, so the moisture already in it does not travel through the wood grain and unbalance the prop; ( the wood is dried to a moisture content of around 15%), so if you have an area of de-laminated 'glass with any hole through it and wet conditions, the wood will take in moisture and unbalance the prop.

 

 

[Oscar]

Bruce: there's more useful information at Post #37 in: Jabiru Prop failure

 

 

[spacesailor]

Just another aside "the flap sanding disk" works well But Wear a "dust mask". please!. differently scented woods smell good but are very bad for your lungs.

 

spacesailor

 

 

[Yenn]

How much truth is thre in the advice about water moving through the prop from top to bottom. I would doubt that water would run downhill if there was dryer timber above.

 

I seldom put my prop horizontal and it runs as smoothly as anyone would want. Air humidity varies from very low to very high here. I would rather let the camshaft sit where it wants, than turn the prop to horizontal.

 

 

[spacesailor]

My thought!,

 

If the prop is horizontal, always on the same side, can it take a droop, & throw the balance out.

 

spacesailor

 

 

[Bruce Tuncks]

I don't think so space. Gliders don't get anhedral from sitting in the heat with wingtips unsupported, although one manufacturer said to put supports in there, time has shown it does not happen.

 

And Yenn, I reckon you are right, but the horizontal prop idea could have come from planes left out in the rain. I can imagine a vertical prop left in the rain becoming heavier on the downhill side. For a prop in a hangar, I agree with you.

 

 

[spacesailor]

BruceTuncks

 

DO SO:

 

I know/knew of a RAF-cadets (ATC, ME!) glider grounded by a droopy wing. Slingsby training glider.

 

And it was in the hanger, mostly. and a "barrage balloon, used for parachute jumping, Great scary fun. Just an information link to Mosquito site. http://peoplesmosquito.org.uk

 

spacesailor

 

 

[Bruce Tuncks]

Was that a wooden glider space?

 

And yes he Mosquito was great, I guess you know the sad story about the Australian ones.

 

 

[spacesailor]

All the "Slingsby's were wooden.

 

If you have the time or are good at internet searching!,

 

Can you find a photograph of the V bomber crash at Nottingham ( Saturday 20th September 1958 it was “Battle of Britain” Day. And like many other R.A.F. stations throughout the country R.A.F. Syerston was staged an open day.). One photo was looking down the runway with a lad with shorts looking at the smoke of the crash.

 

I think it was me (in the shorts, as ATC dress was long trousers,)

 

spacesailor

 

Think I've got it.

 

 

[Bruce Tuncks]

Nope space, there was the Slingsby Vega which was a glass 15 meter type. It made the news with a mid-air breakup. The glider was being flown in Europe at the time. There was a subsequent picture on the cover of Australian Gliding mag of Vega wings being tested to destruction, with the wingtips parallel.

 

I wonder about the expertise of the RAF and gliders...There is a story about a RAF glider in which the officers who had outlanded it left the de-rig to the lower ranks while they ate their pub lunch. The lower ranks couldn't see how to take the wings off so they used an axe.

 

 

[spacesailor]

The AXE!

 

I've De-rigged Hundreds if not thousands, to load onto trucks, then slide them off into the mouth of the smelter, giant radial,s went in with props attached.

 

Most of them big American bombers, were flyable, but alas no pilots to fly them as the yanks went home.

 

Only had a couple of rides in the good Dakotas from RAF bases were we picked up aircraft to scrap.

 

spacesailor

 

 

[spacesailor]

Conceded, The Vickers-Slingsby T-65 Vega 1977, but hadn't Fred sold out & retired.

 

I nearly got another DC3. When the VH-EDC ditched into Botany Bay 24 April 1994.

 

I was sailing passed the end of the runway as VH-EDC took off, then came back again.

 

spacesailor

 

 

[Bruce Tuncks]

The axe story came from an English gliding book I read in the 1970's, and the context was that you should train your crew instead of leaving it to their imagination.

 

Getting back to props, I notice the new Jabiru prop looks pretty good aerodynamically. But is it as gentle on the crankshaft as the old wooden one?