The XPB Stage 1 underway.

[Marty_d]

I use a circular saw for thicker, long cuts actually, not a joke.

Me too. It may not be particularly good for the teeth, but the drop saw does a great job on extrusion and other thick stuff. I keep a "good" 80 tooth blade for woodwork and an old one for aluminium.

 

 

[bexrbetter]

So I'm slowly getting through the thumb pain and the heatwave is going away a little, so getting back up to speed.

 

Concentrating on the tail a bit now and after a few iterations of horizontal stabiliser pivots, have arrived at this mock up - please note just a rubbish piece of square tube to test with, all bolts loose, no nuts even, and not indicative of the final materials used.

 

 

 

 

[Pilot Pete]

Does it work better with the camera upside down ?

 

 

[Marty_d]

He's filming the first loop.

 

 

[bexrbetter]

He's filming the first loop.

Yup, honing my skills for the aerobatic version.

 

 

[bexrbetter]

So I'm almost settled on a design for the center wing crossmember after a bunch of experiments.

 

I have simplified it to a self supporting, easily produced and assembled module, along with far simplified design for the side plates to attach it to the longerons. Both are simply laser cut, folded and bolted/riveted together in minutes - and very importantly, super cheap.

 

I haven't decided on the final material yet so don't take the prototype pieces shown here made from galvanised sheet as the actual finalised product. Sheet steel is less painful to my pocket to throw in the rubbish bin if the design proves to need changes a few steps further along.

 

 

 

 

 

[M61A1]

Trained mice.I'm not sure you are you even serious with that rudimentary question, are you aware of how many aircraft use rivets in tubes ..... a lot, and there's a plethora of tools available.

 

Personally I use a modified 2.5mm allen key modified to suit, in a cordless drill. The 6 sides of the allen key give great grip in the drill too.

 

[ATTACH=full]43049[/ATTACH]

Perhaps?...

Deburr Master | Deburring Tools | Chamfering Tools | Ultra Tools

 

 

[Nobody]

Bex,

 

I hesitate adding this comment as I realise it is difficult to judge with only two photos, but do you mind sharing your thoughts on the pattern of lightening holes in the carry through? I would have thought that the moment was constant through the member and you would want as much material as possible in the top flange. Is there something else going on here?

 

The pattern in the sie with the increasing hole size looks good, following the shear flow.

 

Nobody

 

 

[bexrbetter]

Bex,I hesitate adding this comment as I realise it is difficult to judge with only two photos, but do you mind sharing your thoughts on the pattern of lightening holes in the carry through? I would have thought that the moment was constant through the member and you would want as much material as possible in the top flange. Is there something else going on here?

Yup, there's a lot more going on and I don't actually need either top or lower flanges, but without them I felt it would look too weird for acceptance from the rather conservative, not to mention, gossipy, Flyers.

 

You should see the plane I would like to build!

 

 

Bex,The pattern in the side with the increasing hole size looks good, following the shear flow.

And considerably smaller than what they could be, be I can't align front and rear if I went bigger, would look weird.

 

 

[bexrbetter]

Funny how some things run.

 

Many times you need to compromise on what design you want due to lack of common or easy to source materials.

 

Sometimes it all goes to plan.

 

But there's a few other times that everything not only falls into place, but suddenly you see a chance to do even better and easier with simple design and common materials, and the wings just took a turn that way.

 

I had worked out a simple method and material list for a simple straight wing with dihedral, then when I was playing in the computer a few days ago optimising it, suddenly I realised that it was actually easier and less effort with the same material list to make a gullwing which very few planes have other than a few Gliders.

 

There's some possible minimal aero advantages, but the real reason is they just look better, it's that simple.

 

 

 

[bexrbetter]

[onetrack]

Bex, doesn't the gullwing design mean more fasteners, and multiple wing sections, that detract from the inherent strength of one straight, simple section?

 

 

[bexrbetter]

Bex, doesn't the gullwing design mean more fasteners, and multiple wing sections, that detract from the inherent strength of one straight, simple section?

Again; "I had worked out a simple method and material list for a simple straight wing with dihedral, then when I was playing in the computer a few days ago optimising it, suddenly I realised that it was actually easier and less effort with the same material list to make a gullwing"

 

If you did it in some of the traditional styles of building then in some cases you might be right, but you may have noticed already that I don't do things like other people do.

 

 

[Marty_d]

I look forward to seeing how it's less effort than a straight wing... bottom line is there's a change in the plane of the wing which requires a joint in the skins at the very least.

 

 

[onetrack]

If you did it in some of the traditional styles of building then in some cases you might be right, but you may have noticed already that I don't do things like other people do.

Ahhh, Yes! So this design improvement, is just the gradual progression, towards the fabulous and unique Bex Ornithopter?

 

 

[Pilot Pete]

bottom line is there's a change in the plane of the wing which requires a joint in the skins at the very least.

Arent there joins in the skins of most wings anyway?

[Pilot Pete]

Do you still plan on having a rotatable hinge joint at the root to enable wing fold back with the gull wing?

 

 

[bexrbetter]

Ahhh, Yes! So this design improvement, is just the gradual progression, towards the fabulous and unique Bex Ornithopter?

"design improvement" might be construed the wrong way. I'm not claiming anything is better design wise other than being far cheaper, easier and faster to build.

 

If you equate planes to cars, there's plenty of BMW's through to Ferrari's out there, especially related to price, but not so many Toyota Camrys.

 

bottom line is there's a change in the plane of the wing which requires a joint in the skins at the very least.

Bottom line is there already was a join in the wing skin at the same place, nothing has changed at all, same sheets, same ribs, same spars as I would have used for the straight wing.

 

As I said, and for the 3rd time; the material list is unchanged.

 

 

 

 

 

[bexrbetter]

Do you still plan on having a rotatable hinge joint at the root to enable wing fold back with the gull wing?

Yes, I see a folding wing as a crucial part of the craft.

 

Far too many people complaining about storage costs as part of plane ownership.

 

Some attribute the good sales of the Sonex Onex to it's folding wings/easy storage capability for example.

 

 

[Marty_d]

Arent there joins in the skins of most wings anyway?

Along the length? Not in mine, unless you count where the top skin angles down to the top of the cockpit.

 

 

[bexrbetter]

Along the length? Not in mine, unless you count where the top skin angles down to the top of the cockpit.

Many craft have a full length skin but I choose not to for cost and especially handling concerns, a decision made long before any gullwing considerations.

 

 

[bexrbetter]

Err, Ruffasguts, what is "optimistic" about my comment?

 

 

[ruffasguts]

Err, Ruffasguts, what is "optimistic" about my comment?

must be fat finger trouble .not intentional unknown button pressing

find whatu are doing interesting god luck with it

 

Mick

 

 

[bexrbetter]

must be fat finger trouble

Ha! Yeah, certainly not the first time that's happened!

 

Thanks

 

 

[onetrack]

If you equate planes to cars, there's plenty of BMW's through to Ferrari's out there, especially related to price, but not so many Toyota Camrys.

Yes, and a lot of people forget that the Toyota Camry is one of the biggest-selling cars in the country (beaten only by the Corolla) - and there's very little I can't do in a Camry, that can't be done in a BMW or Ferrari - except perhaps, run at exceptionally high speeds.

The missus has an ASV50 Atara-S and it's actually a very very good car to drive. It corners like its on rails, it's a superb highway car, it produces quite adequate power at 135kw, and I can get it down to 6.4L/100km consistently on a smooth level freeway at 100kmh.

 

The motoring journalists will tell you the Camry is just a POS, typical Toyota whitegoods offering - but these blokes worship the European badges, and won't even consider the massive problems that come with Euro badges, such as horrendous parts prices, over-engineering resulting in constant niggly problems, and massive depreciation.

 

Roll on with the Ornithopter. Just remember, putting a bend in the wings has to have advantages on more than one front, besides looks, and not consuming more material.

 

I'd personally be concerned about the bend producing control and linkage complications, and control surfaces operation complications.