The XPB Stage 1 underway.

[bexrbetter]

The general idea of your carry-through is OK but I'm a bit concerned about some of the details.

By the way, I was in a bit of a hurry today and don't want to be seen as coming off short on HITC's well reasoned and technically correct input (relative) - as usual.

 

I am still fiddling, the structure is incomplete (hell I only decided on Saturday night and I had something to show on Monday!) and HITCs material and sizings were well off what I am using, but otherwise I couldn't think of a airplane or pilot that I would feel more safer in than one designed, built and piloted by HITC, his admirable record in aviation stands and his writings on any subject to do with homebuilding are always to be respected and I wish I had a 1/10th of his hands on real world experience.

 

Also every bit of aluminium you see is 6061, either T5, extrusions, or T6, sheet, and the stainless is 316, this ain't a Bunnings build.

 

 

[Head in the clouds]

Well - thanks for the kind words.

 

I'm quite sure that my guesstimate of the material sizes you've used for the carry through are not likely to be exact, but I still think they look a bit light ...

 

I notice you've not said what the actual sizing is though. On closer inspection of your photos the caps are a little larger than I first thought but I'd be surprised if they're larger than 50x3 angle and since you say it's 6061T5 then at a yield strength of 210MPa they'd calc out at 21.77kg/sqmm and have a cross-sectional area of 291sqmm, giving them a capability of 6.4T - which is still only about half what you need.

 

I'm not meaning to rain on your parade but I really think you need to build the whole carry through on the bench before 'inserting' it through the fuselage. Your photos show that you've riveted it into place via pop-rivets to the angles each side of the fuselage - that's a nice simple attachment method BTW, and quite secure enough since it can't 'escape' vertically, so only needs to be held in location laterally - but if you do plan to solid rivet the web then it'd be much easier bucking it on the bench than trying to do it in-situ. If you use pop rivets you'll be building a very limited service life airframe, they'll work loose in a short while in that highly stressed location.

 

Just for reference I've posted some pictures below of the carry-through I used on AussieMozzie which I never completed, but which is a similar wing arrangement for a pretty much identical weight aircraft. If you compare the size of the structural members you'll see why I think you might be a bit on the light side. Note that on this carry-through I have tapered the spar cap material at the outboard ends where the load is transferred from the aly caps to the nearly 800MPa heat-treated chromoly wing attachment plates, so to compare the actual member size you need to look at the carry through near its centre rather than at the ends, but as you can see, the spars for a cantilever wing need to be quite massive, even when using 6061T6 alloy -

 

 

 

 

 

[Marty_d]

Well - thanks for the kind words.I'm quite sure that my guesstimate of the material sizes you've used for the carry through are not likely to be exact, but I still think they look a bit light ...

 

I notice you've not said what the actual sizing is though. On closer inspection of your photos the caps are a little larger than I first thought but I'd be surprised if they're larger than 50x3 angle and since you say it's 6061T5 then at a yield strength of 210MPa they'd calc out at 21.77kg/sqmm and have a cross-sectional area of 291sqmm, giving them a capability of 6.4T - which is still only about half what you need.

 

I'm not meaning to rain on your parade but I really think you need to build the whole carry through on the bench before 'inserting' it through the fuselage. Your photos show that you've riveted it into place via pop-rivets to the angles each side of the fuselage - that's a nice simple attachment method BTW, and quite secure enough since it can't 'escape' vertically, so only needs to be held in location laterally - but if you do plan to solid rivet the web then it'd be much easier bucking it on the bench than trying to do it in-situ. If you use pop rivets you'll be building a very limited service life airframe, they'll work loose in a short while in that highly stressed location.

 

Just for reference I've posted some pictures below of the carry-through I used on AussieMozzie which I never completed, but which is a similar wing arrangement for a pretty much identical weight aircraft. If you compare the size of the structural members you'll see why I think you might be a bit on the light side. Note that on this carry-through I have tapered the spar cap material at the outboard ends where the load is transferred from the aly caps to the nearly 800MPa heat-treated chromoly wing attachment plates, so to compare the actual member size you need to look at the carry through near its centre rather than at the ends, but as you can see, the spars for a cantilever wing need to be quite massive, even when using 6061T6 alloy -

 

[ATTACH]44131[/ATTACH] [ATTACH]44132[/ATTACH] [ATTACH]44133[/ATTACH]

HITC, in the far future when I design my Spitfire, I would love to seek your opinion on some design aspects!

 

 

[bexrbetter]

I'm not meaning to rain on your parade but I really think you need to build the whole carry through on the bench before 'inserting' it through the fuselage.

From post #243 ..

 

and make it in 2 pieces to save myself stripping the frame down again to get it in but otherwise would be a single piece crossmember support plate.

.. and here is the ex-State 6T riveting press I was looking at last week, not the old green one but the newer, sexy blue one under the black plastic on the left that you can't see ..

 

 

.I notice you've not said what the actual sizing is though.

Yes, no I didn't. As mentioned, the structure is incomplete and there is no point in making determinations based on what you can see currently.

 

 

[flyvulcan]

I thought that the primary aim for this build was to test and validate Bex's construction technique, rather than to build a flyable aircraft. If it happened to result in a flyable aircraft, great. But I think what Bex is doing here is learning how to optimize his building process which he seems to be doing a good job of and he is learning a lot along the way.

 

In the "real" aircraft, he may use different gauge or different spec'd material, he may not have the same number of lightening holes, he may use solid rivets instead of pull rivets etc. If his test sample works with quick to install pull rivets etc, then it bodes well for when he has finalized the design for his aircraft and he conducts the build of his prototype "aircraft" rather than his prototype "construction method test frame".

 

He will likely take on board the suggestions that have been made, in all the areas of design, fabrication and form etc. and consider them on their merits. At the end of the day, thanks to his ingenuity in developing a simple construction technique, combined with his own design input and the input of others, he could possibly come up with a product that works and appeals to the masses.

 

I say Bex, keep at it and forumites, keep making suggestions and inputs (especially HITC whose inputs are extremely valuable).

 

 

[bexrbetter]

.He will likely take on board the suggestions that have been made,

Indeed.

 

I would like to make it very clear that I take all suggestions and comments very seriously and always research options offered even though I have a dig (usually very dry and not noticed) or seem a bit obtuse occasionally with 86000 things going 'round in my head, that's just me.

 

There is no such thing as a stupid question or offering and the very reason I read forums often is to gain knowledge, I can go months without picking up anything and then, boom, a revelation that makes it all worth while - often a bit picked from someone's crazy obscure idea.

 

 

[FlyingVizsla]

Mr FV wants to recommend the book I got for him from EAA - "GA Airfoils - A Catalog of Airfoils for General Aviation Use" by Harry Riblett (sixth edition 1996). Some wives get their husbands socks and undies. I joined EAA and get him interesting books I want to read ...

 

 

 

He thinks it's the bees knees with regard to wing design. Look forward to seeing the Bex Special flying.

 

Sue

 

 

[IBob]

Mr FV wants to recommend the book I got for him from EAA - "GA Airfoils - A Catalog of Airfoils for General Aviation Use" by Harry Riblett (sixth edition 1996). Some wives get their husbands socks and undies. I joined EAA and get him interesting books I want to read ...  

 

He thinks it's the bees knees with regard to wing design. Look forward to seeing the Bex Special flying.

 

Sue

O most fortunate of men.........you'd don't have a spare sister or two, by any chance???

 

 

[bexrbetter]

Look forward to seeing the Bex Special flying.

 

Sue

As I very much enjoy reading yaw updates Sue.

 

O most fortunate of men.........you'd don't have a spare sister or two, by any chance???

IT'S A TRAP, RUN!

 

 

[Pilot Pete]

Love the pun

 

 

[Soleair]

In my work on prototype aircraft design & builds, we would design the airframe first. Then build it. Then use that build as a test item, and test it to destruction.

 

In this way, the assembly methods could be proved, the expense of using aircraft grade materials was not wasted, and valuable insight into how the structure failed at ultimate loads was gained.

 

Bex's system looks interesting, and I wish him well. But it would save a lot of time, effort, & money if he were to design it on paper first, then build & test to destruction a fully representative structure. It will help his own & his future customers' confidence, provide hard evidence to back up tech specs, and go a long way to assist in certification.

 

Apart from the cost element, it is much quicker to rub out lines (ok, hit 'delete' in CAD) & redraw, than to bin hard structure & rebuild.

 

 

[bexrbetter]

Bex's system looks interesting, and I wish him well. But it would save a lot of time, effort, & money if he were to design it on paper first, then build & test to destruction a fully representative structure.

I spend more time in CAD than at the factory actually

 

I just spent 3 days designing a terrific quick release/folding wing system in CAD to find ....

 

A/ I had to rely on someone else for a critical part of the construction - and they couldn't meet my expectations,

 

and

 

B/ The idea and fit-up was awesome on the computer, but quite difficult to achieve with consistency in the real world - I'm not just building one, I'm building something that needs to be repeatable over and over easily by the 'sometimes less than savy'.

 

Besides being stupidly cheap to do so, even in higher grade materials, I'm quite happy with playing around trying for new discoveries on my time with my money and my effort, no need for you to be concerned in those areas, thanks.

 

When the time comes I won't just load test, I will test to absolute destruction to verify.

 

 

[bexrbetter]

I just spent 3 days designing a terrific quick release/folding wing system in CAD to find ....

Make it 5 days now, but I think I've nailed it. Undo 2 easily accessible bolts (inside the cockpit), pull the wing out, twist it and fold it down the side in one easy action.

 

It should result in similar to this - note I am not using this mechanism, posted just to give you the idea only ..

 

 

One aim is to be able to park it into a 20' shipping container.

 

Will get down to the factory this arvo and on the way I will stop for materials - $20 worth of common metals that anyone can buy and a couple of hours work with normal home workshop tools should do it.

 

... and that's part of the goal - buying and building a kit is one thing, being able to maintain and repair it yourself is another.

 

 

[bexrbetter]

I tried to hack my thumb off today with a rabid 4" grinder and thin cutting blade, so there may be no updates for a couple of days.

 

 

[planedriver]

Take great care with those thin cutting blades mate, they'd cut through your thumb in a couple of seconds .

 

Also keep it clear of your middle finger, just in case your car horn packs it in.

 

 

[bexrbetter]

Take great care with those thin cutting blades mate, they'd cut through your thumb in a couple of seconds

Obviously my mistake, I didn't realise you had to hold it there for a couple of seconds to get all the way through.

 

 

[AussieB1rd]

I'm a big fan of wing folding so will be interested in how you go with this there are some very simple ideas out there.

 

 

[bexrbetter]

I'm a big fan of wing folding so will be interested in how you go with this there are some very simple ideas out there.

I have pretty much failed to find "very simple ideas" out there for low wing aircraft. Even when the process is simple, often the mechanism is bespoke and difficult to manufacturer or replace if damaged. I am using $20 worth of common materials that anybody could repair.

 

Some of the high wings are brilliantly simple, bit easier when you have a wing strut to aid the process.

 

 

[flyerme]

I tried to hack my thumb off today with a rabid 4" grinder and thin cutting blade, so there may be no updates for a couple of days.

Hmmm. 10 years ago I was using a 9" grinder with wire wheel to strip down farm machinary for respraying . On the particular day I was wearing track pants and going comando.. I was grinding the draw bar and like an ijet, I pushed my thigh in to grinder for more penetration... Not good !!! In an instant my track pants ripped off me like a chip and dale stripper and grinder ended up in my groin with a ball of ripped track pants.. Pulled grinder away to find my goodies un unrecognisable !!!!!! Went I to shock lol. Boss man raced me to hospital and boy was I relieved when they cleaned me up to find a 6" x 1.5" by 4 mil deep gash in my groin/ inner thigh stopping just before my good bits.. The wire brush had spread bits of flesh and what not all over my goodies making them look .. Well not so good... So no damage down there .PHEW..- Now a huge scar looks like burn scar.. Lesson learned. No loose cloths around wire wheels. Jeans or overies...(overalls;) lol

 

 

[bexrbetter]

boy was I relieved when they cleaned me up to find a 6" x 1.5"

Hot nurse?

 

Got a shocking headache, can't sleep, not sure if it's the injury or the drugs they gave me - or both.

 

That's my excuse, what the hell are you doing awake at 4am?

 

 

[flyerme]

Hot nurse?Got a shocking headache, can't sleep, not sure if it's the injury or the drugs they gave me - or both.

 

That's my excuse, what the hell are you doing awake at 4am?

WX. Recorded 41 kt. Gust and sleet falling. Nasty out there :( And no female nurse :(. Male doc ... Embarrassing. Specially hobbling in with an old greasy sheet wrapped around my lower half lol. Truth... I never sleep ;)

 

 

[Kyle Communications]

i was awake at 3am... been watching youtube videos since ...dying here with the man flu :(

 

 

[Marty_d]

I tried to hack my thumb off today with a rabid 4" grinder and thin cutting blade, so there may be no updates for a couple of days.

Take care of it. Hope you heal quickly!

 

 

[bexrbetter]

Thanks Marty.

 

Bored hanging around with my sore hand today so here is a gif of the wing fold using simple tube and a heim joint .. or rose joint if you're British. The Heim company in America took a licence to produce them in the US while the Rose company did so in the UK in case you were ever wondering.

 

 

 

[AussieB1rd]

so here is a gif of the wing fold using simple tube and a heim joint

Pretty sure a square peg in a square hole wont work, here is a thread relating to some wings folds and a sonex think the first one maybe just what your looking for, or like the other sonex, make the wing root part of the fuse and just fold vertically, if was ok for FU4 Corsair then it should be ok for this lil baby.

 

Folding Wing Modification for a Sonex--considerations