The XPB Stage 1 underway.

[bexrbetter]

So I popped into work this arvo and put a couple more hours in...

 

 

 

 

Oh, and when I said matched hole, that is the skins and ribs, it is difficult to supply spars with pre-matched holes so the skins have pilot holes to make life easy, just drill away, no measuring, pin-punching etc. hassles.

 

 

 

[Birdseye]

Looks very neat, in fact better than many commercial products I've seen. Have you settled on the firewall forward arrangements?

 

 

[bexrbetter]

Looks very neat, in fact better than many commercial products I've seen. Have you settled on the firewall forward arrangements?

Thank you.

 

I am definitely going with an engine and propeller although this had been first choice ..

 

EB Enterprises 121G - Flux Capacitor | O'Reilly Auto Parts

 

Oh and the wing has 1.8 degrees of twist in it for anti-wing tip stall, was as easy as pie, seriously.

 

 

[Birdseye]

Excellent engine choice. Presumably they have both radial and in-line options.

 

 

[Nobody]

Excellent engine choice. Presumably they have both radial and in-line options.

Does it run on mogas? I have heard that plutonium is hard to obtain these days.....

 

 

[bexrbetter]

I have heard that plutonium is hard to obtain these days.....

Phhttt, don't you know how close to the Russian and North Korean borders I live?

 

 

[geoffreywh]

Coming along very nicely....what is the plan re: u/c? a "Grove" type preformed steel or alu bar , 6" Ingegno wheels? I suggest the engine planned for would be beginning with an "R" and not round....Plus those nice 4 cyl Suzuki's that you wrote about...Might be too much engine (if that's possible?)

 

 

[bexrbetter]

those nice 4 cyl Suzuki's that you wrote about...Might be too much engine (if that's possible?)

Yeah I have to think about an engine soon. I do have a Subaru EA81 to immediate hand, but the Suzuki is certainly tempting based on it's availability here.

 

Have a couple of U/C choices, I do have to start thinking about that as well, first i got to work out some rudder pedals and cables so I can get the turtledeck on.

 

 

[onetrack]

It's looking good. Of course, it must be pure coincidence, that it looks more and more like a Morgan Aeroworks Cheetah, with every additional component and photo. We wouldn't expect anything less, coming out of China.

 

 

[bexrbetter]

It's looking good. Of course, it must be pure coincidence, that it looks more and more like a Morgan Aeroworks Cheetah, with every additional component and photo. We wouldn't expect anything less, coming out of China.

It's actually closer to a Zenith 650 using KR2/Morgan build technique ideas.

 

I happen to think the Morgan is good mix of simplicity and robustness, and surprised more don't follow that path, it is certainly one of the easier methods to build a plane.

 

It's no secret, I've mentioned it before, I admired the Morgan build technique so I bought a kit to learn from it, but nothing's copied. You do know the Morgan is a direct copy of a KR2, slightly extended, but in aluminium don't you? Makes your "China copy" joke ironic.

 

I would have been more than happy to build (slightly modified) Morgans by the way, would have been a damn sight easier.

 

 

[Hawkeye]

Looking great Bex.

 

My ideal a/c would be an XPB2 - ie. high wing taildragger with as ASE 750T engine, or maybe the n/a version will suffice.

 

Can't wait to see your finished plane.

 

cheers john

 

 

[onetrack]

Nearly everyone has to get their construction and engineering ideas from somewhere. It is extremely rare for a completely new and original idea to appear.

 

The Americans are just as notorious as anyone else for stealing ideas and designs - and then, when patent lawsuits are lodged, even claiming stridently, that the disputed idea/design is purely their original thoughts and principles.

 

"Prior art" is the classic American defence to any patent lawsuit.

 

 

[bexrbetter]

So ya knows it's time to do the other nose, ya knows.

 

Wing upside down, lay the sheets on to the pre matched holes and pop.

 

 

Flip over, strap the sheets down and play around a bit until you get a few more pre-matched holes lined up. Once you get a few in it lines most of the holes up although you have to fiddle and ream a few on the over laps, no big deal.

 

 

Set up the wing twist and drill/pop a few of the pre-pilot holes along the spar cap to secure the twist ..

 

 

Then get a result ...

 

 

And then there were 2 ....

 

 

 

[Marty_d]

Nice work! I'm assuming you haven't yet riveted to the spar (rear skins would lap under?)

 

 

[bexrbetter]

I'm assuming you haven't yet riveted to the spar (rear skins would lap under?)

The twist is setup with a handful of rivets along the spar holding it currently*, and yes, some will need to come back out to slip the rear skin panels under.

 

*I'm doing it this way in order to check each step as I go.

 

 

[geoffreywh]

Did I miss a step or did the "gull wing" part get deleted along the way? Not that I mind, mind you, but I remember a cute spar set up that has now disappeared. The "washout" looks good and helps prevent those nasty tip stalls.

 

 

[Marty_d]

Did I miss a step or did the "gull wing" part get deleted along the way? Not that I mind, mind you, but I remember a cute spar set up that has now disappeared. The "washout" looks good and helps prevent those nasty tip stalls.

You've been gulled.

 

 

[bexrbetter]

Did I miss a step or did the "gull wing" part get deleted along the way?

Reduced to smaller gull ends and later, wing tips.

 

 

You've been gulled.

'Cause he's gullible.

 

 

[geoffreywh]

oh there it is! The gull was there all the time........In the free flight model world, tapered (thickness and planform ) wings reduce drag and those nasty wing tip vortices. What are the gains in full size aircraft apart from looking really sexy. .....As an aside, Can we PLEASE PLEASE, not have those god-awful wing thip thingies as the Morgan has. (Did I say Please?)

 

 

[RKW]

Some people like those wing tip thingies!

 

 

[onetrack]

There are figures of 3.5 to 5.5% efficiency gains banded around for commercial aircraft winglets. However, aircraft cruise speeds obviously play a large part in those figures.

 

It appears Boeing have decided raked wingtips are enough to get satisfactory efficiency gains on the Dreamliner. At risk of bringing scorn upon my head, Wikipedia has a pretty substantial page on winglets.

 

Wingtip device - Wikipedia

 

I would hazard a WAG that the efficiency gains of winglets on the likes of the XPB would be so minimal, as to be unworthy of inclusion in the design. I'm sure Bex will soon advise.

 

I must admit, I was surprised to find how long they have been around. No doubt the ancient Egyptians had a version, too.

 

As always, Fred Lanchester was a brilliant engineer, long before his time. He thought up winglets 6 years before the Wright Bros got off the ground!

 

 

[bexrbetter]

Can we PLEASE PLEASE, not have those god-awful wing thip thingies as the Morgan has.

Thanks for the tip.

 

 

[pylon500]

Some companies spend years researching wingtip design;

 

 

Some don't think it matters...

 

 

[Birdseye]

Latest example is Airbus resurrecting them, but primarily as a means of increasing effective wingspan without physically extending it beyond the 80 metres footprint permitted under current airport standards.

 

 

[kasper]

and on some wings they are essential:

 

 

Take them off this one and the aircraft is uncontrollable with them on its like an express train on new rails