Author Topic: By Jupiter  (Read 75255 times)

Online Vixen

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Re: By Jupiter
« Reply #375 on: June 13, 2019, 12:12:53 PM »
For the Jupiter propeller, I followed the manufactures drawing (in reduced scale) as closely as possible. There are five 5mm thick laminates towards the top followed by two 11mm laminates with another 5 mm at the bottom of the stack, thats eight laminates in total. The laminates are arranged so that the wood grain alternates. This will enhance the appearance of the finished blades while improving the strength and stability of the blades. The glue bond line between the laminates is just visible.  The joint line is a great help while sanding the blades to the required profile. The joint lines should form  long gentle curves, any irregularities can be easily seen and sanded out.

I roughed the laminations to the approximate shape against the roller end of my belt sander using a 60 grit belt. I used more 60 grit sandpaper, glued to flat and round backings, to sand the blades to the correct profile. The profile was constantly checked against the metal templates. It was a long, slow and dusty process, Thankfully, I have now finished the flat(ish) rear face of both blades. There will be a delay of a few days before I can attempt to carve/ sand the front face of each blade to the correct profile

That Sopwith triplane has been recreated with some magnificent craftsmanship, a tribute to all who help build it. I sometimes think these older wooden airframes and wings look better without the linen and dope coverings. That way you can more easily admire the delicacy of the structure and the workmanship involved. I love the two brass magneto switches, they look as if the came from a Victorian front parlor.

At the Boscombe Down museum of Test Flying, they have a non flying replica of a BE 2 from 1917. It has a n enormous four bladed wooden propeller attached to the reproduction Renault V8 engine. The propeller was carved in genuine Honduras mahogany, The timber used to laminate that propeller came from the big central dinning table that once graced the dinning room in the Officer's Mess (Officers Club)

It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline petertha

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Re: By Jupiter
« Reply #376 on: June 14, 2019, 07:50:23 PM »
It appears to have eighteen veneer thin layers and has a far better finish that the pics convey. It's beauty, in my eyes, is spoilt somewhat by what appears to be silver felt tip pen writing on the blade. I have no idea of the manufacturer - I assume it must be  writing on the blade - 12 inch diameter with a 10 inch pitch I have no idea what the D N stands for though. It was given to me in the last couple of weeks or so - beautifully carved (machined?) and finished  I can't tell you much more than it was intended for use on R/C aerobatic aircraft.  My friend who gave it to me used to fly R/C aerobatics competitively but told me he was always loathe to use it due to it's high cost .

You have a collectors item.
http://www.rcuniverse.com/forum/rc-pattern-flying-101/9431658-asano-prettner-wooden-propeller.html
http://www.orihime.ne.jp/~cac3619/profile/plofile.htm
I've personally ran that same prop early 80's (ex F3A pattern pilot). They were works of art, produced in Japan. Hard to get hold of even then & yes, relatively expensive. Breaking one was a sad day. Many of the top dogs ran them during what I consider the golden era of pattern when turnaround was emerging. That lettering might even be stock, I seem to recall that look. Possibly MK or one of the Japanese accessories companies were (re)distributing them & they had different color stains/finishes too. For some period you could get them semi-finished at reduced cost if you were so inclined. I cant remember what D stands for but I believe N was narrow chord. There were also some small USA based home brew operations that produced decent props. Pylon racing props also had a parallel lineage through this era with even more black magic & voodoo mystique. Then APC entered the scene like a 1200 pound gorilla with highly engineered injection molded props spanning vast P/D increments and that was the end of that for 'woodies'. Sorry about the discussion detour, just so happens to be a memorable chunk of my life :)
« Last Edit: June 15, 2019, 04:28:26 AM by petertha »

Offline Art K

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Re: By Jupiter
« Reply #377 on: June 15, 2019, 02:08:26 AM »
Petertha,
It is a gorgeous prop, and what would we be without detours. I must admit the only thing I had with a prop was a Testors P51 with a Cox .049 that ran once but never flew.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Ian S C

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Re: By Jupiter
« Reply #378 on: June 15, 2019, 02:20:14 PM »
One for the collection, a nice prop on a replica Nieuport 24 owned byTony Scarlett, the engine is a Austrailan made Rotec R-3600 radial.
Ian S C
         

Online Vixen

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Re: By Jupiter
« Reply #379 on: June 23, 2019, 01:30:06 PM »
My battle with the 'brown stuff' is almost over. The 40 inch diameter propeller for the Jupiter emerges from an enormous pile of sawdust. It was a slow and dusty process but deeply satisfying. The smooth flowing lines of the blades are incredibly therapeutic to stoke and fondle when all the hard work is over.

Eight laminates of West African Sapele Mahogany were sawn to shape (slightly oversize) and bonded together with Cascamite Urea-formaldehyde resin. When fully cured, the laminate stack was roughed out against the end roller of a belt sander. The blades were then brought to the requires profiles by hand using only 60 grit Aluminium Oxide sand paper and a set of accurate templates. The sandpaper was glued to flat and round backings, these proved to be very durable and the sand papers did not need to be replaced frequently. The process was slow and produced an incredible amount of saw dust. Unfortunately the weather was unreasonably wet for the time of year, so most of the work had to be conducted inside the workshop. I expect to be cleaning up the dust for months.

When the blades were finally to the correct profile, the propeller was mounted on a spindle and balanced. Quite a bit of extra sanding was required to achieve a balance for both blades and both sides of the hub. Fine sandpaper 150 grit was used to smooth the surfaces before several coats of Danish Oil were applied. Danish Oil is a mixture of Tung Oil, Linseed oils, which are air drying natural oils (oil seeds) which seal the wood surfaces and emphasises the natural grain of the wood.

I will let these pictures do the talking.



















I will do the final assembly to bolt the splined hub into the propeller after the final coats of Danish Oil have been applied and allowed to cure. I expect I will need to add an extra coat of the oil to one side to restore the balance of the blades.

Does anyone out there know of a supplier of 2BA castellated nuts? It would be good to find eight of them for the propeller hub bolts.

Stay tuned

Mike



 
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Online Jasonb

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Re: By Jupiter
« Reply #380 on: June 23, 2019, 01:50:32 PM »
That looks the part.

As for the nuts I would have thought you and the CNC could do them blindfold compared to the other complex parts of the engine.

Offline Chipmaster

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Re: By Jupiter
« Reply #381 on: June 23, 2019, 02:08:47 PM »

Offline fumopuc

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Re: By Jupiter
« Reply #382 on: June 23, 2019, 02:09:58 PM »
Mike, a simple wow.
I donīt want to get hit by one of these ends.
« Last Edit: June 23, 2019, 02:13:29 PM by fumopuc »
Kind Regards
Achim

Online steamer

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Re: By Jupiter
« Reply #383 on: June 23, 2019, 02:48:36 PM »
Beautiful Mike!......yeah I'd make the nuts....

Dave
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Damned ijjit!

Offline kvom

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Re: By Jupiter
« Reply #384 on: June 23, 2019, 02:59:29 PM »
How do you balance a prop?

Beautiful job as ever.

Offline b.lindsey

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Re: By Jupiter
« Reply #385 on: June 23, 2019, 03:05:46 PM »
That prop is just gorgeous!!!!

Bill

Offline Johnmcc69

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Re: By Jupiter
« Reply #386 on: June 23, 2019, 03:14:32 PM »
That's just beautiful! You should be very pleased with that.

 John

Offline Ye-Ole Steam Dude

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Re: By Jupiter
« Reply #387 on: June 23, 2019, 05:06:07 PM »
Hello Mike,

Stunning!  :ThumbsUp:

Have a great day,
Thomas
Thomas

Online Vixen

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Re: By Jupiter
« Reply #388 on: June 24, 2019, 11:44:52 AM »
Thank you all for calling in. it's always appreciated.

Kvom, I was only able to do a static balance of the prop. The prop was mounted on bearings and free to turn, make sure the door is closed and the fan is off otherwise the prop can spin in the breeze. With the propeller horizontal, it is easy to see which is the heavier blade. With the propeller vertical you can also see which side of the hub or blades is heavier. I sanded more material evenly off the heavier side of the hub and off the leading edge of the heavier blade until a balance was achieved. It takes a lot of sanding to remove even a small amount of weight.
When the surface finish has fully dried and hardened, I will need to repeat the balancing, this time by applying an extra coat of Danish OIl to the lighter blade.

Mke
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Ian S C

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Re: By Jupiter
« Reply #389 on: June 24, 2019, 01:19:13 PM »
Would you not have the nuts plain with holes drilled for lock wire rather than castellated nuts, then again the hole in the corner of a 2 BA nut is going to be a bit small.
Ian S C

 

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