Flair Junior 60 Build

[Arron Davison]

Hi guys

Need some help please I am building the above got to the centre wing section plans and instructions go a little vague here!

[David Davis]

If I remember correctly you have three or four quarter-inch ribs making up the centre section, two 1/4" spars one above the other and another about 2/3rds the way back, a leading and tgrailing edge. You now have to cut slots in the centre section ribs to accomodate the plywood dihedral braces, then prop the wings up to the correct height and allow the glue to dry.

I reckon that any white glue would be suitable for the purpose of gluing the wings together, others would recommend using half-hour epoxy and increasing the thickness of the dihedral braces. Your choice, but if you want something aerobatic build a pattern ship!

[Arron Davison]

Are the spars still 1/4 X 1/4 as the pre cut slots are a lot deeper! I have taken photos but do not no how to up load them?

[David Davis]

I really can't help you there Arron as I no longer have the plan and I was working from memory.

As for uploading pictures it's not that difficult. You have to start an album but I can't remember how I started mine. Perhaps you have to click on the "camera" icon in the top row, I really can't remember but someone who's better with computers will be along in a minute to advise you.

[ken anderson.]

Arron...I've sent you a photo of my JNR 60 center section,have a look at it and its pretty straight forward..... mine is from the Flair kit which was built in 1991...yours may be a different plan/kit....have a look...

ken Anderson...ne....1....JNR Dept.

[Mike Etheridge 1]

This plan / elevation was supplied in the 1955 Keil Kraft New Junior 60 which is the same as the Flair Junior 60, whereas the Ben Buckle Junior 60 is the 1946 version with slimmer fuselage. The drawing shows the wing centre section detail:

Perhaps I can scan this drawing again so that the centre section is shown fully/

Edited By Mike Etheridge 1 on 26/08/2017 20:26:58

[Mike Etheridge 1]

New scan showing the centre section detail which does not appear to include the ply wing braces. Many have recommended beefing up the ply braces from what was originally specified so that the wings do not fold due to stunt manoeuvres.

[brokenenglish]

You're getting off track with wrong data concerning the wing spars.

In the original 1946 J60, the mainspar is one hefty spar, 1/4" wide by about 5/8 or 3/4" deep. There is a secondary top spar (square), under the rear edge of the LE sheeting. That's all, only those two spars, and I think that's the version that was mentioned in the OP. Note that this same spar layout is also used on the Majestic Major and on the APS Just Junior, but Ben Buckle added an additional rear lower spar on the Majestic Major, for extra strength and covering support.

The three 1/4" square spars are one of the mods. in the 1955 version, which I don't think is the model being built by the OP.

 

Edited By brokenenglish on 26/08/2017 21:02:15

[Mike Etheridge 1]

B E, I have both versions of the Junior 60 and certainly the Flair model is a copy of the 1955 version. I have the Flair plan also, but my original 1955 plan was stolen apart from the detail drawing above. I can confirm that the Flair plan and Keil Kraft plan match. However I have a copy of the Ben Buckle plan but it would appear that the wings were shown on a separate drawing which I do not have. AD needs to confirm then which model he is making. The width of the Flair version fuselage is 4 inches , the width of the Ben Buckle fuselage is 3 1/2 inches.

Edited By Mike Etheridge 1 on 26/08/2017 21:28:48

[Braddock, VC]

OP entitled Flair junior 60 build.

Be very careful when you're out driving, old bill do roadside sight tests.

[brokenenglish]

OK, I don't know why, but I was under the impression that the OP had a Ben Buckle kit...

Anyway, just to clarify, I've just cobbled up the wing ribs for the two versions, from stuff on my hard disk.

Here are the wing ribs:

[brokenenglish]

Posted by Braddock, VC on 26/08/2017 21:26:35:

OP entitled Flair junior 60 build.

Be very careful when you're out driving, old bill do roadside sight tests.

Not in France they don't, but I'll bear your advice in mind!

One last point, it was said that the spar notches are much deeper than 1/4" (which misled me), but on the 1955 version, the spar notches are much deeper on the three centre section ribs, 1/4" thick.

Edited By brokenenglish on 26/08/2017 21:32:02

Edited By brokenenglish on 26/08/2017 21:32:43

Edited By brokenenglish on 26/08/2017 21:33:15

[David Davis]

There are two Junior 60 threads running simultaneously on this forum. Both models fly well providing you don't over-stress the wing with violent aerobatics.

This thread refers to the Flair Junior 60 which, as stated above, features the wider 1955 fuselage and three-spar wing.

The other thread refers to the Ben Buckle kit with the narrower fuselage and weaker two-spar wing **LINK**.

Hence the confusion.

[PatMc]

Posted by Arron Davison on 26/08/2017 16:26:52:
Hi guys

Need some help please I am building the above got to the centre wing section plans and instructions go a little vague here!

Here's a couple of pics of my Flair Jnr60 centre section -

As you will see the wings have peg & screw retention instead of elastic bands. Refer to the drawing in Mike Etheridge's second post fit W5 & balsa (shown as plastic wood) block if using bands.

BTW the peg & screw wing retention addresses the wing folding problem as well as looking neater than the designed method. If rubber bands are prefered, modifying the cabin to allow front dowels to be positioned much higher will do the same but not as cleanly.

[Arron Davison]

Hi Pat,

That is perfect thank you.

The question i have is why is the cut so deep for the 1/4 spars and dihedral braces?

As you can see from yours they are not flush to the bottom surface?

This is what i was worried about do i glue them all the way in like yours?

[Dave from the future]

Is it just because the centre ribs are flat bottomed and don't have the undercamber that the other ribs have, so the centre section sits flat on the fuselage top?

[kc]

An original Albert Hatful drawing is available on Outerzone and this seems a little clearer on the centre section.

PatMc said "the peg & screw wing retention addresses the wing folding problem" But why & how? ( I don't disbelive you PatMc but just interested in how!)

Edited By kc on 05/09/2017 13:49:10

[PatMc]

Posted by kc on 05/09/2017 13:48:45:

PatMc said "the peg & screw wing retention addresses the wing folding problem" But why & how? ( I don't disbelive you PatMc but just interested in how!)

I believe that the wing folding problems aren't because the wing structure is weak but because the distance between the dowels holding the wing bands & the wing is too great. If the front dowel was positioned closer to the wing, as in most similar designs, the stretch limit of the bands would be about 1/4 as much for the same holding power. This extra flexibility allows the wing LE to be pulled away from the fuselage even when quite moderate G is pulled (such as during loops or panic situation recovery by beginners) causing an increase in the A of A which in turn increases the G force further etc ... until either the limit of the bands' stretch is reached or the wings fold or both. Even if the wings survive this excessive load they stand a fair chance of being weakened & if subjected to the same treatment several times are likely to fail eventualy.

Drawing below is fairly accurate to scale illustrating what I mean.

Blue spot is Jnr 60 design dowel position, red spot more common position.

Of course using pegs & screws, as I've done, eliminates any unwanted increase in A of A during high G manoevers.

BTW the same design limitation is true of the KK Super 60, though I notice that the drawings in OZ show the wing dowels moved to similar positions to the front one in my drawing.

 

Edited By PatMc on 06/09/2017 22:06:02