Junior 60 build

[kc]

That dotted line indicates to me that it's the LE sheeting in the 'glued at LE position' -perhaps it's then bent down  after glue has set at LE.

[David Davis]

In my opinion it's the undercambered wing section which gives the Junior 60 its grateful flying characteristics.

[Geoff S]

9 hours ago, kc said:

That dotted line indicates to me that it's the LE sheeting in the 'glued at LE position' -perhaps it's then bent down  after glue has set at LE.

 

Ah yes, I think you're right.  It's not exactly either necessary or all that useful information.  It seems odd to clutter an already crowded drawing.  Well spotted.

[Christopher Wolfe]

1 hour ago, Geoff S said:

 

Ah yes, I think you're right.  It's not exactly either necessary or all that useful information.  It seems odd to clutter an already crowded drawing.  Well spotted.

 

Actually it is quite useful information for a beginner builder to prevent them making the mistake of glueing the sheeting to the top spar and then trying to make it fit to the L.E. later.

 

Personally, I would trim the front edge of the sheeting (to ensure that it is straight), dry fit and mark the top spar location, cut to fit, dampen the outside and glue into place using balsa cement at the leading edge seam (for sandability) and an aliphatic adhesive to attach to the wing ribs and spar.

 

A few pins and maybe some tape to hold everything in place, make a cuppa, eat your supper and leave to dry overnight.

 

* Chris *

 

 

[Lowandslow]

Just in case you’re interested Geoff when repairing my Ben Buckle JR60 electric kit I made the nose about 40mm longer and as a result have been able to dispense with any additional lead nose weight. Dry fit the under slung battery box to achieve the desired CoG. All up weight on the original was almost 4lb and now it’s nearer 31/2lb.

[Geoff S]

10 minutes ago, Lowandslow said:

Just in case you’re interested Geoff when repairing my Ben Buckle JR60 electric kit I made the nose about 40mm longer and as a result have been able to dispense with any additional lead nose weight. Dry fit the under slung battery box to achieve the desired CoG. All up weight on the original was almost 4lb and now it’s nearer 31/2lb.

 

That had crossed my mind, too, at the risk of horrifying purists 🙂   I did a similar thing when I built a Limbo Dancer from the plans of the kit version I destroyed.  I found it difficult to get it to balance on the first build.  40mm is quite a lot to add but if it saves weight ...  

 

Worth thinking about.

[Lowandslow]

You’ve already upset the purists Geoff by mentioning electric 😂

[PatMc]

I added some nose weight to mine to achieve the cg shown on the Flair kit plan when I built it around 1986 & it was ic powered. When I re-furbed & converted it to electric around 2012 I removed the nose weight incrimentaly until the cg was back to the point shown on the pdf posted earlier. It now has a better glide & wider speed range than originaly but is just as benign to control. As mentioned in an earlier post KK didn't specify a cg position on the plan of either original versions but probably suggested builders found a cg position that suited themselves by trial & error over the ubiquitous long grass. 

 

BTW it's a fallacy that the engines used in models like the Jnr 60 were heavy compared with today, the first Jnr 60 I saw was in 1956 it was F/F & powered by a either a Yulon 30 or 49 (I don't know which) glow plug engine. The owner also had a single channel later version Jnr 60 powered by an ED racer. The Yulon 30 weighed about 5 oz the 49 about 6 oz, the ED racer about 5.5oz. Petrol engines of the era were also lightweight  but required a battery & ignition coil, however these latter were usually sited with the cg in mind.   

 

Another fallacy is that 4s ic power is in keeping with the period of vintage models whilst electric power isn't. There were no suitable 4stroke engines for Jnr 60 size models until around the late 1970's early '80's. Even then the first available were 40 size & a bit OTT. OTOH the first electric powered RC model - a Radio Queen - flew on electric power around 1957. Graupner's & Sanwa were also flying FF electric powered models around a year or two later. Pete Russell successfully coverted his STOL Mk 1 to electric power as an experiment about 10 years before the OS40 FS appeared.

Edited September 23 by PatMc