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Author Topic: KK Minimoa. Couple of Qs  (Read 414 times)
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TheLurker
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« on: May 31, 2019, 03:56:24 PM »

I've been wanting to have another go at a Minimoa for a very, very long time but there are a couple of things to sort out before I make a start, which I'm hoping to do early next year.

Removeable Wings
I intend building the next one at 70%-75% of the original plan span to make it a) eligible for hi-start and b) easier to store but if at all possible I'd like to build it with removeable wings because of b) because even at ~36" I'm pushed for storage space.  I have some half formed ideas about this, but I'm more than happy to steal adopt someone else's proven solution if anyone else has done this.

Anhedral outer section of wing
First time around I bottled* setting the anhedral outer section on the wing by cracking it.  Guess what? A Minimoa will fly, sort of, with just dihedral set at the wing roots.  Every time I fish out the plan I look at this and think there must be a better way to build the wing.

Various thoughts on this.
+ Leave the spars outboard of the crank point unglued to allow them to "creep" a bit so they're not under undue tension after cracking.
+ Build on an angled jig/former
+ Build the wing as two sections setting the anhedral angle on the inner section outer rib.

I like the simplicity of the third option, but am concerned that it may not be string enough and I can't see how to make the first option work.  Advice / suggestions welcomed.

Cheers,
Lurk.

*I was 10 rising 11 , Dad was working away from home as was the supplier of the kit my "Uncle" Bill so although there is a degree of shame felt at my lack of gumption I don't lose any sleep over it.  Smiley
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applehoney
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« Reply #1 on: May 31, 2019, 06:13:18 PM »

Pushing my memory back over some seventy years ..  does not the Minimoa already have removable wings? Tongue and box attachments which, for me, almost guaranteed that a wing would fall off under tow or in flight.

Not a design I remember with affection but .. each to their own.  :-)
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SP250
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« Reply #2 on: May 31, 2019, 06:55:14 PM »

Lurk

The KK 50" MM does indeed have tongue and box removable wings - job done with an elastic band and small hooks holding them together.

Most effective way to build the wing is with an angled building board for the gull section. 
However if you double up the ribs where the anhedral tip joint is and halve the angle for each of these ribs when building flat, that will do as its a very "squint scale" model.

John M
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TheLurker
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« Reply #3 on: June 01, 2019, 05:15:40 AM »

Quote from: "applehoney, SP250"
applehoney > ...does not the Minimoa already have removable wings? Tongue and box attachments which, for me, almost guaranteed that a wing would fall off under tow or in flight.

SP250 > The KK 50" MM does indeed have tongue and box removable wings ...

It certainly does, but my first attempt had the wings fixed permanently because I didn't trust the friction fit.  I was a cautious sort of soul even then and I couldn't see a good way to secure the wings other than with lashings of ginger beer balsa cement.

Quote from: "applehoney"
Not a design I remember with affection but...
A tendency to lose a wing will generally have a deleterious effect on one's opinion of a design. Smiley

I'm not expecting it to be a great flier, especially scaled down, but an historical wrong (i.e. my first attempt) must be righted.


Quote from: SP250
Most effective way to build the wing is with an angled building board for the gull section. 
However if you double up the ribs where the anhedral tip joint is and halve the angle for each of these ribs when building flat, that will do as its a very "squint scale" model.
Thanks for that John.  Confirms my opinion of the cracked spar approach as "cracked".

Lurk.
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DavidJP
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« Reply #4 on: June 01, 2019, 05:26:14 AM »

Much as I recall my association with the Minimoa but one thong I can say is mine flew very well.  There was a slope in the local park and launched from the top of that it went on for ages.  I was also about 11 and had a little help from my cousin who suggested retaking the wing via a peg (matchstick) through the wing and tongue.  I much later built one about 8 or 9ft span which I flew off the slopes
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TheLurker
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« Reply #5 on: June 01, 2019, 05:34:09 AM »

Quote from: DavidJP
...via a peg (matchstick) through the wing and tongue. 
I was thinking a bit of soft/medium infill between the stringers over the top of the wing with a peg feeding into the box and each tongue (much like full size gliders) so it's very good to know you've already proved the idea works. I'll steal ideas from anyone, I'm not proud. Smiley
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Graham Banham
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« Reply #6 on: June 02, 2019, 03:31:09 AM »

Mine  (going back 40 years) never lost a wing due to the wing falling off the tongue, with no other retention other than friction: i don’t remember the plan showing any additional securing method, and the anhedral wasn’t a problem as from memory it’s barely there, if at all: the outer wing panels are either flat or have reduced dihedral compared to the inners.

What the tongue and box setup on the plan isn’t is anywhere near strong enough for the tow (KK Chief anyone?). If i were doing it now i’d use a pair of wire joiners across the fus and alloy tubes extending several bays into the wings. You can still do the hook and band thing across the fus, or better still, magnets.

Substantial braces across the fus between the LE’s and TE’s are essential to avoid the wing pivot/ fus crush effect, and i infilled the nose between the stringers on mine: in retrospect i should have done this back to the wing LE.

Flew nice and slowly though, but only when calm.
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DavidJP
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« Reply #7 on: June 02, 2019, 06:19:45 AM »

Only 40 years - then you can remember it all very easliy. Wink  I am pretty sure the matchsticks we used were not very strong (just post war and all that) and I remember the old men sitting down and splitting them in half - two for on you see.  And if you are wondering how they struck them without breaking - well they were held very close to the tip - the finger tips almost over the bit that lit - yes it burnt the finger and you could always tell who practised that because their index finger tips was scorched!

After nearly 70 years I don't honestly remember how I dealt with the dihedral break but what ever I did must have worked.  Today I would most certainly use magnets to secure the wings.

My other favourite in the range was the Pixie.  I think I built about three - a half size one for indoor would look cute!

So wish you well with your build Lurky old boy - will watch with interest.   
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DavidJP
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« Reply #8 on: June 02, 2019, 06:30:04 AM »

Meant to add that if you are building from try KK plan on the outer zone copy there is comment about the ribs not fitting and they offer an alternative.... but I think VMC now produce one so have probably corrected it all. But then I think you are proposing building a reduced size version - so the OZ plan may be the one to use as it can be easily resized.   
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TheLurker
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« Reply #9 on: June 03, 2019, 02:44:03 PM »

Quote from: Graham Banham
....the tongue and box setup on the plan isn’t is anywhere near strong enough for the tow ...
....Substantial braces across the fus between the LE’s and TE’s are essential to avoid the wing pivot/ fus crush effect, and i infilled the nose between the stringers on mine: in retrospect i should have done this back to the wing LE.
That's worth knowing.  Thanks very much.

Quote from: DavidJP
... the ribs not fitting and they offer an alternative....
The "original" rib profiles on the OZ copy of the KK plan are utterly barking mad (they're some sort of Gottingen profile, mebbe G652) and bear no resemblance to the kit ribs I remember cutting out.  The OZ plan has some much saner profiles as well which look more like what I remember from my build.

Quote from: DavidJP
...VMC now produce one so have probably corrected it all.
They do and at forty quid it's very tempting, but I do want a ~36" span version

Quote from: DavidJP
...the OZ plan may be the one to use as it can be easily resized.   
Aye.  I already have a photo-reduction of it to about 75%, but I think I'll probably end up tracing it and working up a clean SVG and then PDF version that'll let me scale to an exact span.  The local print shop only charges a couple of quid for an A1 print from PDF.

Lurk.
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TheLurker
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« Reply #10 on: June 21, 2019, 03:54:05 AM »

Good news/bad news.

Good news; VMC are releasing a brand new 50" Minimoa.  There was/is a link to Farcebook on the VMC website.  I don't "do" Farcebook so can't tell you any more, but it sounds like a ground-up rework.

Bad news;  It reads as though it's designed for RC and they're also discontinuing/have discontinued the KK Minimoa.

I'm a little sad to see the demise of the KK kit, but as noted upthread by Graham there were a number of issues with it and if the new VMC kit can be built as freeflight model for us skinflints that won't spring for RC kit then there is no bad news.


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DavidJP
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« Reply #11 on: June 21, 2019, 04:07:15 AM »

Possibly VMC are  mindful of the coming need to be able to keep the model in the field nowadays and hence radio.  Can you not just buy the plan?  I don't do disgrace book either so can't help there!

Not a case of being a skinflint on the radio - just prefer FF so will do it whilst I can.  I just can't get back into radio!
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TheLurker
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« Reply #12 on: June 21, 2019, 04:17:50 AM »

Quote from: DavidJP
...- just prefer FF so will do it whilst I can.  
Likewise.  Decent radio gear is far more affordable these days than it used to be, but I much prefer the (relative) simplicity of freeflight. The fact that it's cheaper as well is bonus. Smiley
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FreeFlightModeller
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« Reply #13 on: June 21, 2019, 05:16:03 AM »

The Minimoa was always on the list, but never built one.

For me, free flight is about the model flying .... radio control is too much about the pilot. FFF!
(free flight forever ... it's a covert group  Roll Eyes  )
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DavidJP
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« Reply #14 on: June 21, 2019, 07:23:42 AM »

Actually Russ, my old China, the way things are going I think there is a fair chance that it will be FF Forever.  At least with the smaller and lighter models anyway.  I am quite surprised on the number of FF people one meets.  And a number have gone the full circle and back to FF after doing radio.  And as you say, it is what aeromodelling is all about.  That and folk like old Lurk here with his sense of humour.........   Helps maintain a balance in todays troubled world!
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