I'm drowning, in bits of an Mu28

[gerryb]

hi keith,
the blue and orange lines in your sketch show exactly what you don't want-humps.  gentle sanding rather than 'all guns blazing'  will bring down the filler to the profile you need.

as you sand down the filler, use a straight edge laid across the wing/filler/wing. as you begin, you will see daylight underneath the straight edge.  as work progresses and the filler goes down, you will see less and less of a gap underneath the straight edge until finally the edge will roll across the wing in a smooth movement without any homps , bumps or hollows.

don't forget you will be veneering the wing with obechi and that will also help to maintain the curve.

re the spar itself,  the most important part of it is the vertical part between top and bottom carbon pieces.  on a 4m wing, please do not leave this piece out.  it is carrying most of the loads and stresses and will strengthen your wing way more than if you leave it out.

[Happy Days]

Okay Ger,….I’m still not totally sure that I’m gonna be able to get the profile dead right, but then, as I was told once by a wise man, “Precision engineering is a question of compromise!” :roll:

If it goes wrong I’ll blame you.

BTW just as an aside………I was up on Mt’ Lienster today. Great conditions, warm breeze, broken cloud, plenty of lift.
Anyway, I nearly managed a vertical ‘8’ The Alpina has much better energy retention than the other planes I’ve got.
What I’m lacking at the moment is balls! :oops:

K.

[gerryb]

hi keith,   you jammy dodger!!!!!  sounds like you had a right good day's flying.    we were on tountinna tonight and if it wasn't raining, it was covered in cloud and a howling gale for good measure.  still, we got some flying, but not enough to satiate the fagacites.

re the attainment of perfection vis-a-vis wing sections......it's what we all strive for but somewhere along the line we have to say 'that's fine'. otherwise, we would never get anything finished and into the air.  as another wise man said, (a frenchman as it happens) "we are weekend flyers".  so i suggest you work out a plan of action,  get yourself set up on the work bench,  and take the plunge.  as the nike add says  'just do it'.    you'll be glad you did.    

[Happy Days]

I have no idea what “fagacites” means. :?  (Personally I think you’re just showing off with all these strange words!)

As for ‘just doing it’ I guess you’re right, although I can see myself producing one wing half with one profile, and the other wing half with a slightly different one. The plane will probably end up flying round in circles. :roll:  

(But then they do say, “One good turn deserves another” :lol: ……………Okay,….I‘m going …)

[Fred]

AAhhh Keith! Good to see that you started the Mu!  :clap:

For the wing, don't bother too much!
Cut the groove, put your carbone tape, use a bit of light (polyfilla) filler, and off you go!

I can guarantee that you will not see any difference in the way the glider is flying.

[Happy Days]

Ahhh!…….good to see you back Mon Ami.

That’s the conclusion I came too after all the other good advise I received.

Work on the wing has stopped for the moment while I build a stronger and longer work bench ……Longer… for obvious reasons, and stronger… because of the total weight it’ll have to support when the obechi is applied.

I’ve also had to take some time out to perform open heart surgery on my beloved Alpina :shock: , following an disastrous launch. :cry:
I really don’t know what went wrong. I launched the plane, she flew for a moment before flaring up vertically, stalling, falling back down and landing on her tail,(still verticle) then cart wheeled onto her right wing tip. At this point the fuse broke in half   (literally half way along its length.)

I couldn’t believe my eyes, and promptly burst into tears. :oops:  A very nice young lady  (probably in her eighties) tried to consol me in my distress and offered me a tissue to wipe my eyes.

K.

[Fred]

:lol: nice lady, keep her if you can!    

Good luck with the repairs, thanksfully, a fuselage is easy fixed, but let us know if you need some help  

[Fred]

Was browsing the Interweb, and found this...



Motivation back?  :mrgreen:  O:)

[Happy Days]

Okay, okay,……I’m working on it!


The three sections of the left wing half are stuck together, carbon tape has been epoxyed into the top of the wing and light filler sanded down to aprox profile shape.
Two days ago I epoxyed the obechi to the top of the wing as you can see in the picture. Unknown to me at the time, some of the epoxy has percolated through the obechi and stuck bits of the top foam blank to the top of the wing! You can see the little bits of styrene on the top of the wing. They’re not just laying there,…..they’re stuck there! :oops:  


Some constructors recommended using 700+ kgs weight when gluing the obechi, some told me they had just used old telephone directories,……I ended up using 300kg over the entire wing half, with most of the weight concentrated near the root half of the wing.

I’m still haunted by the thought of these wings snapping half way through a tight loop so I’m going to insert a wooden spar and another strip of carbon tape on the underside of the wing. But first I need to find a Wing joiner socket to fit into the root of this wing half.

So, little by little she starts to take shape.

Just turning to Freds picture, it does look a quite magnificent beast! (The plane I mean, not the guy carrying it ) :roll:

K.