ASK-13

[Fred]

Oh, and forgot, 3 degrees from 1mm or 2 metres from the centre line, it's the same  

[andrew wallace]

ok guys the dihedral is measured in degree's and minutes so the measurement is 3 degree's 30 minutes which works out at 3 1/2 degrees  :lol:  :lol:

thanks to GEEW from www.scalesoaring.co.uk for explaining it  :clap:  :clap:

[andrew wallace]

i've just drew out what 3 1/2 degree's looks like over 75 inches
at the tip the dihedral will be 5 inches

[gerryb]

hi andrew, you seem to have dih sorted out on k13. have you decided on wing joining system yet? in his 'bible' cliff shows how to build a full length box spar using balsa and ply. i followed this method for my k13 and built a brass box/ steel bar joiner into the box spar. this brass box can be fixed to the spar on its centre line, looking at it from the front.  i also used brass box across the full width of the fuse to carry the steel bar. this means the dih angle is carried right into and across the fuse.  it also means i had to stagger the brass boxes, one in front of the other. because the spar is raked forward and the  brass boxes are at right angles to the fuse centre line, i widened the top and bottom spars to ensure the brass boxes were securely attached to the formers within the spar.
using this method provides you with a very strong wing but you must make sure your measurements are accurate from the start. after almost 20 years and several less than perfect landings, my k13 is still going strong.
 by the way, have you thought of a colour scheme yet? i used the dublin gliding club's ei112 scheme. i think they also had the same scheme with another reg. might be nice to see them both up together, (just a thought).
regards, gb

[andrew wallace]

hi Gerry
thanks for that reply, i have been pondering over the wing joiner now for a few weeks  :?:
one of the ways i had thought about doing it is the was you have described
i have a 1/4 scale pat teakle Pic20 and it's done the same way  

haven't thought about the colour scheme yet but i do like the idea of yellow

[billscottni]

I know you've done more than this Andrew! Let's see some more pics!

[andrew wallace]

after seeing Gerry's ask13 and alans ask8 thought i'd need to get my finger out
i've now sorted the brass box for the wing joiner in the first four ribs


made these arms for the air brakes out of 2mm aluminium


got some supplies today glue, pins and i brought some silicone paper from work great for building on nothing sticks to it  


so i might get a bit done over the next few days  

[Happy Days]

Not if you drink all those Budweiser's you won’t! :lol:

[andrew wallace]

ok guys i've had a cracking summer flying now it's time to get back to the building  

at the minute no glue has been added when i'm happy i'll start and glue everything down

only problem i'm having is with the first four ribs the first rib(no 0) seems to be much bigger than the rest is this right maybe Gerryb can help
the rib is the right size i've checked it against the plan

it's nowhere near the other ribs
do i have to bend it down  :?:

[billscottni]

Is it maybe supposed to be angled to give the dihedral angle?

[andrew wallace]

good point bill  :clap:
i have the first rib at an angle and maybe it's not enough :?:

i'll have to have a look again  

[andrew wallace]

had a look at the full size K13 at the ulster gliding club it's all stripped down and on a trailer
i noticed the first rib is also bigger on the real thing so i'll have to bend the rib down or something :?:

[billscottni]

Is it almost like a "fillet" shape then Andrew?

[gerryb]

hi andrew,
good to see you're back at the building board.

that root rib is a pain in the ass to deal with. the bottom of the rib is not flush with the rest of the ribs. it extends above and below the other ribs, so the height of the rib in your photo is not accurate.

lowering the rib will ease the stress on the spar and allow you to fit it to the root rib easier.

the other thing you can do is cut the spar slot deeper in the rib so it runs straight across all the ribs. you can then add balsa to the top of the spar to fair in the ribs to a streamlined finish.

because the rib extends above & below, i would suggest you leave the root rib off the wing until you have more of the wing constructed. you can then push the root of the wing over the building board for fitting the root rib.

in the previous photo you show the trailing edge fully pinned to the board. i would advise you raise the wing tip about 6mm to allow for a few degrees of washout. this washout starts at the aileron root. in slow flying a/c like the k13, washout is very important, especially when setting up for landing.

hope this helps, keep up the good work, gb

[andrew wallace]

ha gerry i knew you would sort it  :clap:
i'm going to take your advice on lowering the main spar think that would be the easier option  :clap:
the trailing edge isn't glued down yet i was thinking about the wash out  :?:  but i have it all sorted in my head now so hopefully things will move along fast now  

don't know why but i find it hard to build during the summer months and once it comes to september can't wait to get in the shed