Nieuport research

brinesharks · 1 May 2009, 05:48 AM

Quote:

Originally Posted by Doug Bigler

3. Why would they have used ash rather than Spruce?

Ash is stronger than spruce for a given cross section, and harder. I know Sopwith used spruce for capstrips and birch plywood for rib webs. I think Nieuport used solid poplar for webs so maybe the ash capstrips compensated for the absence of plywood there. Sopwith also went from using spruce in Pup spars to using ash for the Camel's spars, probably in response to Pup wing failures.

The Nieuport did use 5mm Poplar - I had assumed it was Poplar ply! Makes a lot more sense now...

I plan to use 6mm Birch Ply with Poplar webs with Ash capstrips as per the original.

One thing I don't understand is why they would use 8mm Maple fuselage formers on the turtle deck? Any suggestions?

Doug Bigler · 1 May 2009, 09:56 AM

Re: "I would be very interested in reading documentation of the circumstances surrounding such PUP wing failures. The mechanics of this would be most informative. Could you please point me in the right direction?"

Joe,
I first read of Sopwith wing failure in a ~1980 Cross & Cockade article "The Pup's Predecessor: The Sopwith SMLTBP". It described a SMLTBP built in Australia by Basil Watson who flew successive loops at an airshow and induced wing failure resulting in a fatal crash. I also read (can't remember where) about a RFC pilot who performed the same manouver in a Pup with the same result, while trying to demonstrate the strength of the Pup's wings. In Bruce's book on the Pup, in the chapter on training, a pilot is quoted saying he was afraid to loop or tight spin the Pup because of its reputation for losing its wings and he never saw anyone else perform those manouvers in the Pup. There is also listing of a Pup losing its wings at 2000' in the latter part of that book. The book also refers to a lot of shoddy workmanship being found in Pup wings, to complicate things. Don't know specifics on exactly which parts failed.

Brinesharks,
Can't comment on the maple other than that it's a strong and hard wood.

Joe Perkel · 1 May 2009, 08:30 PM

Quote:

Originally Posted by Doug Bigler

The Sopwith SMLTBP". It described a SMLTBP built in Australia by Basil Watson who flew successive loops at an airshow and induced wing failure resulting in a fatal crash..

Doug,

Thank you! I have to dig out my PUP Datafile (in a box somewhere), but I do recall the reference to Basil Watson. Apparently a former Sopwith employee who ran off with some drawings, (the modern equivalent of stealing from Los Alamos).

The interest is in the identical spar sections for the Baby / Schneider. My suspicion, is a structure specific stress concentration, and not so much cross sectional failure. Just a guess, will try to dig a bit, but no reference to such failures in the several hundreds of operational Babies and Schneider's, so that lends a bit of credence to my supposition.

Thanks again!

brinesharks · 17 May 2009, 04:18 AM

Another research question - the Hardesty drawings state that the interplane struts are 'hollow' Spruce. I don't have any reference on the extent of the hollowing. Any ideas?

brinesharks · 6 November 2009, 03:38 AM

Ok - a whole lot more research and some lucky breaks have answered my own question.

Here's an excerpt from Flugsport magazine:

It shows the cross section of the struts with dimensions plus the lower attachment point (answering another question I had about the shape of the fitting!).

brinesharks · 6 November 2009, 03:43 AM

Continuing on from the discussion of various woods - I have been educating myself about wood bending. Several references suggest that Ash is an ideal timber to bend and steam bending is recommended. However they also say that Spruce is difficult to bend (in one book the author says it's the hardest to bend successfully) and another says that soft woods should not be steam bent rather soaked in water and then held to shape until dry.

j ferguson · 6 November 2009, 03:59 AM

Those look like splines in the section. Do you know what material they might be?

That's a really nice drawing. Are there a lot of other similar drawings?

john

karrart · 6 November 2009, 09:56 AM

Quote:

Originally Posted by j ferguson

Those look like splines in the section. Do you know what material they might be?

That's a really nice drawing. Are there a lot of other similar drawings?

john

Here's a quicky I remembered- right off the top of my head!
Robert Karr
The Fine Art of Aviation/Robert Karr, Grant-Free Artist

John McKenzie · 6 November 2009, 10:59 AM

Hi all ..These tongues in grooves , are used for alignement and to prevent the two ,pre-hollowed out halves, from slipping about under glue pressure .
They are short grain hardwood , but Birch or similar ply would do very well . From memory , they would be about 8 x 2.5 mm x Length ,..The central grain running in the 8mm direction if 3 ply wood .
This is a common method in use at the time on many different aircraft ,for hollowed out , 2 part sections . and can be seen also in the Nieuport wing spars .
In the Nieuport interplane struts , the hollowing stops short of their ends.

Re Bending , It is as easy to bend Spruce as Ash , However , Ash , being more open grained , takes less time to absorb water . ..In general , for cap strip size pieces , Just soak in cold water overnight , say in the bath ( If you dare ! ) , then next day , place in a tank / trough of boiling water ( with a lid ) , over the gas stove , for about 8 minutes ,keeping just below the surface if possible , so as not to dry out , then quickly remove and bend over the former ...Allow to dry for about a day ...You could with advantage , allow an extra 15 % over the required bend , for spring back .
Same method can be used for steaming , but its more critical in not overheating the thin timber and causing brittleness ...
Generally use about 1 hour per 1" thickness of timber for up to an inch thickness.
Dont forget , The wood expands considerably when steamed/boiled and it may be necessary to take this into account in form tool design .
Regards John.

brinesharks · 6 November 2009, 08:09 PM

Thanks for all the responses. The Flugsport magazine must have been a great read in its day. Their artists certainly did good work. Karrat shows the other drawing of Nieuport parts from the mag. I also have the original Rozendaal article which has some sketches in it.

John M - thanks for the advice on bending. I'm used to doing model capstrips and water/ammonia was an easy way of doing it. The Nieuport lower wing isn't much bigger than the models I used to build either!

I now have the cross section dimensions of the struts but it seems Rozendaal didn't detail any struts in his drawings. The Macchi drawings I have only show the Ni11 struts and I assume they are different as the Ni11 wings were different sizes and sweep back compared to the Ni17.

BTW - can anyone suggest a way of cutting the aerofoil profile inside the struts? I could do it easily if they were 'through' grooves but not sure how to do stopped ones with that profile. Is it a case of using various plane iron cutters and smoothing the rest by hand/scraper?