Junior 60 build

[Geoff S]

In a weird brain spasm, I've decided to build a 3 channel Junior 60. I have a set of wing ribs and (hopefully) enough balsa in stock for the rest. I've never had a model like that (I built a standard 4 channel trainer when I started out) but, in my increasing dotage it seems to suit a more relaxed flying style (of course it may bore to extinction 🙂 ) It will be electric, probably with a 3S 2200 LiPO for energy and whatever motor seems suitable.

 

One thing I have noticed is that vintage type models don't track very well on the ground for take-off.  I put this down to a very forward undercarriage which seems to be designed to protect the propeller for free-flight landing rather than ROG take-offs - presumably they were hand-launched.   So, at the risk of being criticised for modifying a perfect good old design, I intend to put the wheels in a more conventional position at about the wing l/e.

[J D 8 - Moderator]

Here is my Mercury Matador built in 1971/72 with DC Saber and flown FF back then. Attic queen for many years until fitted with radio assist and a throttled PAW 09 a dozen years ago and still airworthy. It to has forward UC position from the time most had to carve their own prop. Mostly hand launched ROG is possible on short grass, a wire tail skid that drags in the grass to start with helps keep straight I recon.

  Second model is an OD I built 28 years ago, I wanted to push the limits as to how aerobatic a rudder elevator model could be. Large control surfaces make FUN GUS highly aerobatic, somewhat hairybatic I say when rudder/elevator stick is in the corners. Things like flick twinkle rolls are possible, fast spins both ways up, even end over end tumbles if one sets up the entry right.  Be gentle on the stick and it is like any other Rudder elevator type.  Go for it the way you want it I say.  John.

 

[Skippers Walker]

Hi Geoff, Well done with choosing the J60. The original design in all it's formats just goes on and on. A reliable flyer in most reasonable wind conditions, I usually give my electric conversion air time when conditions are fairly calm. Great fun just cruising around on a nice day. I've built a number of the 'golden oldies' in recent years and yes, they can sometimes be a bit tricky to taxi. I usually wheel em out into wind by hand and then enjoy the flight!

Have fun building and flying your model, you won't be disappointed. I strongly suggest that aerobatics are a bit risky and quite unnecessary in my opinion. If you want loops and roll get the right model for the job.

Best wishes

SW

[payneib]

I built mine direct from the Ben Buckle kit, there's no need to move the UC - once it's moving the rudder works. You need to think of an almost "flying taxi" to get proper ground handling. 

 

I'd advise a larger battery - mine fly's on 3s 2600s (full set up as recommended on the 4max website) and still needed 150gm+ of ballast in the nose. The bigger the battery, the lower the useless weight penalty. 

 

Flying it will, eventually, bore you to death. The most exciting it really gets is trying to get low, tight, close in lazy 8s. But Ye Olde Timer aircraft are the most therapeutic of builds. 

[John Lee]

I fly a Super 60 when the mood takes me. I would not want it as my only model but it is just great when the occasion fits.

 

I'd suggest that you mix the Rudder to Aileron 100% so that you can instinctively steer with either stick for a seamless transition from ground to sky. And I also use a larger battery, 3000-3300MAh in my case.

[Mike T]

My J60 has the u/c in the designed position and gives no problems.  The forward positioning gives the plane it's characteristic appearance and stance.  If you're that concerned about ground handling, then maybe the Super 60 is a better option?

[David Davis]

The Junior 60 was my first successful r/c model built from a Flair kit so I have a soft spot for the model. Bear in mind that there are two sorts of Junior 60: the original 1946 design and the 1955 version which had a wider fuselage stronger wing and larger rudder. These modifications suited the heavy receivers of the period. https://outerzone.co.uk/plan_details.asp?ID=9995 and https://outerzone.co.uk/plan_details.asp?ID=1398 They are a great relaxing flyer in calm conditions. I've built two of them and plan to build another over winter covered in doculam and tissue and powered by a 15 glow.

 

Two pictures of mine to encourage you.

 

 

[Edgeflyer]

I also have a soft spot for mine. Bought used for near nothing, oil soaked and thick Solartex covering. It flew so well I decided to restore and electrify it. 3 channel control is fine. Hovers into a good head wind and lands at near zero ground speed. No problem with take off even with it's tiny rudder. Also love my old Southerner 60 and I have a Buccaneer and KK Falcon being restored.

[PatMc]

Hi Geoff, which version are you building ? The 1946 version as in the Ben Buckle kit or the 1955 version as kitted by Flair ?

 

 

[Geoff S]

I'm not sure. I've downloaded the drawing from both Outerzone and Aerofred (they seem to be the same) which I think are the updated ones to allow for single channel control.  There's just a tiny rudder and it looks like no elevator.  I assume the expected power source would be a diesel engine with a set throttle.  I may make the rudder a bit bigger and add elevators, obviously.  I think the tail is supposed to be detachable but I'll probably have it permanently attached.

 

I don't think I've ever built a model exactly to plan.  There's usually something I change, even if it's very minor.  In any case, even kits rarely show every detail and leave some up to the builder.  This will be no different - after all, no servo mounts or battery access are shown, so all that will be 'invented' by me. It'll still look like a Junior 60, though but it'll be my Junior 60 🙂  The drawings don't show the dihedral other than by using the wing brace angle as a guide but I don't suppose it's super critical as long as it's the same both sides ... and a lot more than I'm used to.

[cymaz]

I had a Flair kit, fitted with an SC30fs. I had to raise the trailing edge wing seat by at least 1/8” to stop it taking off nearly vertical 🙄

[David Davis]

8 hours ago, Geoff S said:

I'm not sure. I've downloaded the drawing from both Outerzone and Aerofred (they seem to be the same) which I think are the updated ones to allow for single channel control.  There's just a tiny rudder and it looks like no elevator.  I assume the expected power source would be a diesel engine with a set throttle.  I may make the rudder a bit bigger and add elevators, obviously.  I think the tail is supposed to be detachable but I'll probably have it permanently attached.

 

I don't think I've ever built a model exactly to plan.  There's usually something I change, even if it's very minor.  In any case, even kits rarely show every detail and leave some up to the builder.  This will be no different - after all, no servo mounts or battery access are shown, so all that will be 'invented' by me. It'll still look like a Junior 60, though but it'll be my Junior 60 🙂  The drawings don't show the dihedral other than by using the wing brace angle as a guide but I don't suppose it's super critical as long as it's the same both sides ... and a lot more than I'm used to.

 

Geoff if you have a look at the 1955 plan you'll see that there are three 1/4" wing spars.  https://outerzone.co.uk/plan_details.asp?ID=1398, two spars above one another at the wing rib's highest point, connected by inter-spar webbing and another halfway between these ribs and the trailing edge.

 

I helped a fiend build a Ben Buckle Junior 60 which is based upon the 1946 design. His model, the maroon and white one, is pictured below.This only has two spars: https://www.benbucklevintage.com/index.php?main_page=product_info&cPath=2_9&products_id=85.

 

You said that you had a set of wing ribs. By identifying whether you have two or three slots you'll be able to work out which version you have.

 

Incidentally, Ben Buckle's prototype seems to have been powered by an ED Competition Special. I'm surprised that this engine developed sufficient power to fly it.

 

[Geoff S]

Both drawings I have, as well as the CNC cut ribset I've indulged in, show 3 0.25" spars, so presumably it's the later version.

 

The rudder seems tiny.  Is it adequate or perhaps worth making bigger?   The J60 in David's picture above has a much bigger rudder than my drawings show. It also seems to have a separated elevator (there are 2 push rods), so does the rudder extend below the tailplane as on most modern models?

 

I've also downloaded a pdf with construction sketches that must be quite old because it describes how to put 2x30v batteries in series for an HT supply and how to fit the battery for the escapement (I don't think I'll attempt an escapement).  It also says that the dihedral is 6" at the wing tips.  It's interesting that the wing span is always described as 60" when it is, in fact 63". 

[David Davis]

Both of my Junior 60s have been built off the Flair plan. In that plan the rudder pivots off a piece of 1/4" square balsa located at the highest point of the fin. I will build a similar fin and rudder when I get round to building my next Junior 60.

 

Frans' maroon and white model, built from a Ben Buckle kit has a much smaller rudder. In flight it was not an issue until you were trying to land. The reduced airflow made the rudder very unresponsive.

[PatMc]

17 hours ago, Geoff S said:

I'm not sure. I've downloaded the drawing from both Outerzone and Aerofred (they seem to be the same) which I think are the updated ones to allow for single channel control.  There's just a tiny rudder and it looks like no elevator.  I assume the expected power source would be a diesel engine with a set throttle.  I may make the rudder a bit bigger and add elevators, obviously.  I think the tail is supposed to be detachable but I'll probably have it permanently attached.

 

I don't think I've ever built a model exactly to plan.  There's usually something I change, even if it's very minor.  In any case, even kits rarely show every detail and leave some up to the builder.  This will be no different - after all, no servo mounts or battery access are shown, so all that will be 'invented' by me. It'll still look like a Junior 60, though but it'll be my Junior 60 🙂  The drawings don't show the dihedral other than by using the wing brace angle as a guide but I don't suppose it's super critical as long as it's the same both sides ... and a lot more than I'm used to.

Geoff, I'm not sure if you realise it but the bold printed parts of my post are links to Outerzones latest uploaded version of the KK original Jnr 60 plans as opposed to plans re-drawn by Ben Buckle & Flair (IMO the 1955 version is preferable from our POV).

I built mine in about 1986 from the Flair kit but made a number of modifications.

Most important IMO one was to add a new birch ply former & use wing bolts instead of elastic bands. The designed use of long distance between wing & band anchor point allows too much "stretchability" of the band for RC flying. This can cause the wing LE to lift in mild aerobatics & even sharply applied elevator corrections, which can cause too much G force & subsequent folding wings. Many people have advocated beefing up the wing centre joint but failed to identify the reason for the problem, the wings on mine are not beefed up in any way & the model has been looped, rolled flown inverted etc with no issues since it was built. In fact I've managed to loop it a number of times & roll a couple of times using the old single channel full rudder only spiral down to build up speed although I did sometimes cheat & also judiciously use throttle control (but never elevator) - buttock clench excercising manoeuvers if you're up for it. ☺️

The other mods were to make the tail removable for maintenance, to facilitate an inverted engine's fuel tank position, pull - pull control connections & occasional fitting of floats.

Finaly the original KK plans didn't show any CG position, it may have been suggested in an instruction leaflet but I'm not aware of this, those shown on BB & Flair plans must have been the kit makers' preferences. When I converted my Jnr to electric power I incrementally removed the nose weight until the CG ended in the position shown in the attached PDF sketch. Result is that the model can be flown over a wider range of speeds than previously to suit prevailing the wind conditions (or my mood) merely by using elevator trim & throttle control.

 

Jnr60_mods full size.pdf

 

PS Here's a link to my Jnr 60 conversion from ic to electric

Edited September 21 by PatMc

[PatMc]

9 hours ago, cymaz said:

I had a Flair kit, fitted with an SC30fs. I had to raise the trailing edge wing seat by at least 1/8” to stop it taking off nearly vertical 🙄

I use throttle control & elevator trim - it's easier 😉

[kc]

2 hours ago, PatMc said:

The other mods were to make the tail removable for maintenance,

It might be useful to know exactly how you made the tail removable yet still aligned - bolts or rubber bands?

[PatMc]

58 minutes ago, kc said:

It might be useful to know exactly how you made the tail removable yet still aligned - bolts or rubber bands?

It's shown in the bottom right of the Jnr60 mods PDF sketch.

[Geoff S]

That's very useful, Pat - particularly the pointer to your thread about the restoration of your old J60.  It seems as far as J60s go there many ways to skin that particular cat.  I've printed the starboard wing drawing and stuck the A4 sheets together and cut some 1/4"x1/4" spars from a sheet so I should at least have a wing in a few days (I'm just hoping the electricity stays on with a thunderstorm rumbling away as I type).

[kc]

15 hours ago, PatMc said:

It's shown in the bottom right of the Jnr60 mods PDF sketch.

Sorry, I didn't notice that as it was very small on the screen when I opened the pdf.  Viewed with the photos in that old thread makes it clear.  Altogether a very ingenious but simple system that could be used on many other models too for transport or storage.

Edited September 22 by kc

[Geoff S]

I've printed  parts of the drawings I downloaded from the Outerzone and there are some interesting anomalies.  They're not too serious but they are there.

 

eg

 

 

That's one of the very nicely CNC cut ribs from the set I bought last week laid on top of the rib drawing of the Outerzone drawing I've printed.  It matches very well - even perfectly.  However, when actually assembling the parts over the drawing, the extra single wing spar and the trailing edge are 1/4" out from where the spar needs to be to fit the rib notch.  Obviously the parts are king and the wing will be built to suit the ribs.  It just seems odd. 

 

I hadn't appreciated that the wing is under cambered and that the rear spar needs too be packed up about 2mm because it doesn't lie flat to the building board.  Nothing's glued yet - I'm still pondering 🙂  

[kc]

It seems that the Ben Buckle plans show a flat bottom wing while the Outerzone plans show undercambered.  

 

If you have not already seen it the book on RC library ' Big Four '  (free to download )explains how the Junior 60 was developed into the Super 60

[PatMc]

2 hours ago, Geoff S said:

I've printed  parts of the drawings I downloaded from the Outerzone and there are some interesting anomalies.  They're not too serious but they are there.

 

eg

 

 

That's one of the very nicely CNC cut ribs from the set I bought last week laid on top of the rib drawing of the Outerzone drawing I've printed.  It matches very well - even perfectly.  However, when actually assembling the parts over the drawing, the extra single wing spar and the trailing edge are 1/4" out from where the spar needs to be to fit the rib notch.  Obviously the parts are king and the wing will be built to suit the ribs.  It just seems odd. 

I think the reason for the anomaly is that the plan is showing a "typical" wing section it doesn't claim to be the actual section. KK didn't normaly print their ribs or formers etc accurately on their plans as they didn't want people building from their mates plan instead of buying a kit. Which of course means that Ben Buckle & Flair kits may not have 100% accurate parts of the originals.

 

Here's a chunk from OZ 1955 plan with the "typical" rib rotated 90 degrees confirming what you found.

 

 

[PatMc]

9 hours ago, kc said:

Sorry, I didn't notice that as it was very small on the screen when I opened the pdf.  Viewed with the photos in that old thread makes it clear.  Altogether a very ingenious but simple system that could be used on many other models too for transport or storage.

Glad you liked it. I've modified the tail units or tailplane alone on about 7 or 8 models that I currently have as I've built them. Some, like my Jnr 60 & Magnatilla only ever the tails removed for maintenance etc but some of my electric gliders routinely have their tailplanes removed for storage & transport between outings.

The Jnr 60's is a little over-complicated as I wanted to keep the elevator linkage pull-pull but out of sight.

BTW another reason I do it is that I have more trust in bolted on tail unit than a glued in place one. 

Edited September 22 by PatMc

[Geoff S]

3 hours ago, PatMc said:

I think the reason for the anomaly is that the plan is showing a "typical" wing section it doesn't claim to be the actual section. KK didn't normaly print their ribs or formers etc accurately on their plans as they didn't want people building from their mates plan instead of buying a kit. Which of course means that Ben Buckle & Flair kits may not have 100% accurate parts of the originals.

 

Here's a chunk from OZ 1955 plan with the "typical" rib rotated 90 degrees confirming what you found.

 

 

 

That sounds reasonable. I hope it doesn't apply to any former drawings, too.  I'll have to be careful when building the fuselage.  At least my J60 will have a bit more wing area and hence lower wing loading (probably) than the original kits.  I'm also curious as to what that dotted diagonal item is - the one that starts at the leading edge of 'typical wing section' figure.