The XPB Stage 1 underway.

[Deskpilot]

Hmmm, not sure that I like it. Why didn't you keep the trailing edge on the same angle as the rest of the wing. I realize that you've got more area to help prevent to wing-tip stall but..........

 

 

[Bruce Tuncks]

Yep, I agree with deskpilot. It looks structurally wrong.

 

One question though, how much washout is going into those wings?

 

As far as engines are concerned, I would be wanting to fit a Jabiru engine if that were an option.

 

Thanks Bex for the reports.

 

 

[geoffreywh]

sorry Bex, My understanding is that to prevent tip stalling the tip leading edge should have a negative twist? ie: washout....( or have I read it wrong. (Quite possible) and that last bit of wing just has to follow the aileron line, please.

 

 

[bexrbetter]

I realize that you've got more area to help prevent to wing-tip stall but..........

Exactly, I have more area to help prevent wing tip stall .... "but" what?

 

But you're against attempts to help prevent one of the biggest killers in flying?

 

It looks structurally wrong.

A zero foundation comment that sadly can't be unseen.

 

The coming load test will prove otherwise.

 

One question though, how much washout is going into those wings?

 

sorry Bex, My understanding is that to prevent tip stalling the tip leading edge should have a negative twist? ie: washout....( or have I read it wrong. (Quite possible) and that last bit of wing just has to follow the aileron line, please.

I swore I posted it, apparently not, although it is here ..

 

My extraordinary plane build ... - Page 9

 

The wing washout is 2 degrees by wing end, the trailing edge of the wing tip independently has 2 degrees neg twist by it's end, so obviously it arrives at 0 degrees AoA.

 

 

 

[kasper]

I vote not aesthetically pleasing.

 

Twist itself avoids/delays tip stall which is the killer you reference but twist on a tapered wing will work just as well ... though added wing area at lower angle of attack out there will also add more protection.

 

BUT I would drag up the issue posted above on roll control - more wing area outside the aileron will slow the response rate even more ... I would love to not have the inset aileron on my old 95.10 sapphire to increase roll response but I'm not modding the wings for that.

 

I've not a crystal ball but I can foresee you modding your wing tips to put taper in to the tip and to have aileron out to the tip

 

 

[Bruce Tuncks]

Sorry Bex, I should have just said it doesn't look attractive. I see the logic about tip stalling. There are other ways to address this like airfoil change and washout as has been suggested

 

 

[bexrbetter]

I vote not aesthetically pleasing.

Oh well, we'll just have to wait and see what it looks like when finished.

 

Twist itself avoids/delays tip stall which is the killer you reference but twist on a tapered wing will work just as well ... though added wing area at lower angle of attack out there will also add more protection.

Yes, I have twist (washout) and added area.

 

No problem Bruce, thanks for the clarification.

 

 

[pylon500]

OK, makes a little more sense with the chordline diagram.

 

 

I'm assuming it is the tip section that has the twist, as opposed to the whole wing?

 

Having the taper ratio change at the tip (getting proportionally wider) is going to do some odd things to the span loading on the spar out there, but probably OK.

 

There does seem to be some pointless complexity going into this thing, to say nothing of the overkill of rivets from what I can see so far.

 

The spar rivet pitch looks OK, but have look at the rivet pitch on the wing ribs of a Cessna or Piper, not unusual to have nearly 2" pitch on only 3/32 rivets.

 

Still not sure what the scalloped doubler on the ailerons is for?

 

I had promised myself not to get too involved as I figured most beginners pick up some of the standard way of doing things before they get too far in, but your resources seem to be able to let you go ahead in leaps and bounds...

 

Maybe missing a few pointers along the way?

 

Can't find the 'chin scratch' emoji

 

 

[bexrbetter]

I'm assuming it is the tip section that has the twist, as opposed to the whole wing?

Not sure what the problem is with my English, maybe I've been offshore for too long?

 

I be best friend you mister.

 

I said;

 

The wing washout is 2 degrees by wing end, the trailing edge of the wing tip independently has 2 degrees neg twist by it's end, so obviously it arrives at 0 degrees AoA.

 

Note the entire wing is 2 degrees positive (washout) and the grey area trailing edge tip is 2 degrees negative.

 

Or one could imaging the grey area as a 'Mini Flap' set at 1 degree (included angle)

 

I think the planform in respect to the wings looks dandy myself ..

 

 

 

[bexrbetter]

Because I can ..

 

 

You guys need to stop worrying about the rivets, as with everything else, I have proven there's a plan.

 

 

[flyerme]

Because I can ..[ATTACH=full]50953[/ATTACH]

 

You guys need to stop worrying about the rivets, as with everything else, I have proven there's a plan.

I have to agree with Bex here in regards to the wings WAIT UNTILL ITS FINISHED to deside if she is pretty or pretty ugly. I just spent 7 hrs on a painting and my wife said " whats that crap?" Then 20 mins later she was amazed at the end result when the lil details went in in the final process. In saying that the CAD pic above looks pretty sweet to me And has a nice destiction anout it that stands out. I may be wierd but i actualky like it

 

 

[onetrack]

Bex, have you got, or can you get, access to a wind tunnel, to check on whether the actual airflow over the entire wing structure is performing, or will perform, as designed? Many a time, a calculated result is not the same as actual result.

 

 

[bexrbetter]

Bex, have you got, or can you get, access to a wind tunnel, to check on whether the actual airflow over the entire wing structure is performing, or will perform, as designed? Many a time, a calculated result is not the same as actual result.

Not that complicated, simple foil, normal parameters, nothing special, nor a requirement for the time and money when I am able to change things rapidly while testing. The aileron and flaps are adjustable in mere minutes for reflex, those wing tips are nothing to reshape and refit (not even finished yet either) and I can adjust the wing's AoA a little on the run.

 

Oddly enough, I do (or did) have access to a windtunnel, and military at that. But how many manufacturer's designs at rec flying level have ever seen a windtunnel.

 

 

[Bruce Tuncks]

My next kit aircraft will be a matched-hole metal plane. I still reckon fiberglass is a better material but it is so dusty and sticky that I want a change.

 

So keep up the good work Bex, and yes the wingtips look ok on the full plan view where you can see the tip chord is not greater than the aileron-end chord.

 

 

[bexrbetter]

the tip chord is not greater than the aileron-end chord.

Yes that was a "WTHell?" moment, will be rectified next time, not changing it just for the sake of change at the moment.

 

However, a little Paint Shop Pro touchup, and add a shark fin, and I know for sure you guys are now drooling.

 

 

My next kit aircraft will be a matched-hole metal plane. I still reckon fiberglass is a better material but it is so dusty and sticky that I want a change.

High wing I presume?

 

 

[geoffreywh]

Oh no! not the shark fin. Will it be removable?

 

 

[Marty_d]

Oh no! not the shark fin.

He's soup-ing it up.

 

 

[pmccarthy]

Shark fin soup later?

 

 

[SDQDI]

Anyway that puts to rest the argument that he won't ever Finish it.

 

 

[bexrbetter]

I've had enough of these bad puns,

 

Fin.

 

 

[bexrbetter]

These days I have been very busy with some other important issues, but getting a bit into the plane.

 

At the moment I am sorting the pedals and seating, that go hand in hand for positioning of course.

 

For the pedal shafts I am using some bushings that needed clamps to be made and I am very happy the position I am in now to make these things myself. I spent a total of 2 hours drawing the clamps, going to the laser shop and cutting them, then to the sheetmetal shop to fold them, and now I have a couple of sets of very suitable, and identical clamps.

 

If you notice I laser pointed tabs on each end for the fold guy to accurately position them. All folded at once and later the joins whipped off with an angle grinder.

 

It is important that they could be replicated at home if they ever needed to be replaced in the future, and as you can see some drilling and folding in a vice would produce them, albeit not quite as accurately abd as fast as the CAD and laser.

 

 

 

[geoffreywh]

neat

 

 

[PA.]

These days I have been very busy with some other important issues, but getting a bit into the plane.At the moment I am sorting the pedals and seating, that go hand in hand for positioning of course.

 

For the pedal shafts I am using some bushings that needed clamps to be made and I am very happy the position I am in now to make these things myself. I spent a total of 2 hours drawing the clamps, going to the laser shop and cutting them, then to the sheetmetal shop to fold them, and now I have a couple of sets of very suitable, and identical clamps.

 

If you notice I laser pointed tabs on each end for the fold guy to accurately position them. All folded at once and later the joins whipped off with an angle grinder.

 

It is important that they could be replicated at home if they ever needed to be replaced in the future, and as you can see some drilling and folding in a vice would produce them, albeit not quite as accurately abd as fast as the CAD and laser.

 

[ATTACH=full]51049[/ATTACH]

This would make it easier to trim.

 

 

[bexrbetter]

Today I built the front floor inclusive of rudder pedal shaft mountings, what the brackets above are meant for.

 

Ready to be fitted, and then I can work on rudder cables which is stopping me from fitting the turtledeck.

 

 

 

 

[geoffreywh]

good idea using those pipe clamps!