minimoa mo2a -chris williams plan and cliff evans kit

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chris williams
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by chris williams » 06 Oct 2018, 17:23

OK, FBI investigation under way... First of all, R1c is too short: my mistake. Amended PDF attached. Now look at the pic of the root rib. This is actually all the root ribs superimposed on each other. You can see that the spar slots are all identical (Good old Compufoil). So, I've printed out part of the plan and cut some more ribs and...presto a similar result. Putting two of the ribs side by side on the spars shows that they are at a different angle. To quote Douglas Adams: 'this is, of course, impossible'. Have to prepare for MW now, so further investigations will have to wait until Monday
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P1050209.jpg
P1050213.jpg
Ribs Composite.jpg
R1c R2-6a.pdf
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mick a
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by mick a » 06 Oct 2018, 17:39

thanks chris
thought i was going nuts !!
will await the out come , thought was strange as rest of it all fits perfect

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chris williams
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by chris williams » 08 Oct 2018, 21:12

Having seen that two other ribs are slightly misaligned, the cause of the problem is obvious: despite my careful cutting out of the slots, the slight discrepancies involved in the manual creation of the ribs are the culprit. This is exacerbated by the depth of the spars, which are so specified as to make the glueing area at the gull join sufficient for the job. The solution should be relatively simple: ease out the slots for the upper spar to allow the ribs to take up their proper position. The inner panel ribs will be aligned by the two TE segments and the flap spar; the outer panel ribs will be aligned by the aileron spar. (I have always done this without fiddling with the slots: presumably the spruce is flexible enough to take up any of the differences)
In the case of the MO2a, when the wing is locked into shape with the addition of the top sheeting, the two short lengths of TE either side of the flap are clamped to a straight edge whilst the glue dries...

The foregoing must be true, I have a hangar full of wings that say so!
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IMG_2449 copy.jpg
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mick a
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by mick a » 09 Oct 2018, 00:58

thanks chris
just to get it correct, i should make the slots in the root ribs 1b wider so they fit onto the short
trailing edge at root , and the same for the 1c ribs ?
the ribs you show in pics are for the outer wing , not built that as yet
when i pin the spar on the plan the back of all r1 ribs are off the plan, which seems correct as the shape of ribs dictates this , if i cut the slots in 1b and 1c to fit to the short trailing edge , i will then have a gap at the top spar ( i can always fill this )
have tried again and still twists
just going to glue all up and try to get twists out later as just going round in circles
just looks like lots of washout on inner wing

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chris williams
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by chris williams » 09 Oct 2018, 07:59

Wing twist at this stage is irrelevant. It's not until the wing is on the jig supports and the top sheeting added that it all gets locked in place. As it stands at the moment you can twist the wing in any direction you like!

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Cliff Evans
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by Cliff Evans » 09 Oct 2018, 08:03

All these twists and turns! Isn't making model aeroplanes fun!

mick a
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by mick a » 09 Oct 2018, 12:01

that’s one way of putting it Cliff
it will get there , just can’t seem to get it to work at the moment , so think will just leave it for a while - hope the balsa gods will sort it
...

mick a
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by mick a » 09 Oct 2018, 12:25

thanks Chris
will do that , the spar won’t twist at the root
rib , as the joiner box is there and it’s solid
just concerned about lack of contact from the first 3 ribs at the root as wanted this to be strong and it seems i have to keep adding little bits in , it just doesn’t seem strong and it looks like i’m just bodging it up as i go along
but keep going

Tom Pack
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by Tom Pack » 09 Oct 2018, 13:58

mick a wrote:
09 Oct 2018, 12:25
thanks Chris
will do that , the spar won’t twist at the root
rib , as the joiner box is there and it’s solid
just concerned about lack of contact from the first 3 ribs at the root as wanted this to be strong and it seems i have to keep adding little bits in , it just doesn’t seem strong and it looks like i’m just bodging it up as i go along
but keep going
Do 1 of 2 things........1 cut a whole new rib with the correct spar slots.....or 2 cut a partial rib and double up the area where the gaps are from making the existing rib “fit”.

mick a
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Re: minimoa mo2a -chris williams plan and cliff evans kit

Post by mick a » 09 Oct 2018, 14:58

yea i think that’s what i will do
although already cut 4 new ones ,
just want to be sure all in correct place
with the root ribs etc as once all glued in
that’s it ,so just trying to figure out a
point to measure everything straight from
as every time so far (4 attempts ) it’s been wrong eithe trailing edge spar to high / too low
etc etc
hopefully will do

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