Junior 60 incidences

[cymaz]

Sc 30fs I had in mine...great little motor. It needs as much lead as is required...if that doesn't sound too odd.

Closed loop on rudder and elevator, love the idea, very classy. Miss it out on the throttle though.

I added about 1/4- 3/8 to the TE wing seat. That stopped it flying like a home-sick angel.

Enjoy the phut- phut of the little 4 stroke as you quietly and gracefully do T /G's on a warm, calm summers' evening...ah bliss

I crashed mine when the wings clapped

[gangster]

Bob. Yes agree it's best to get the lead at least to the far side of the bulkhead 3/8 dowel sounds a little clumsy but not Terrible 1/4 square hard balsa would be fine. I am a little surprised it is underpowered with that motor. If you want to Fly it through the sky even like a 40 powered trainer you will be making trim changes for the rest of your life. The J60 is an elegant gracefully old lady. Fly it with minimum power and enjoy its beauty and grace And that is coming from someone who for most of his modelling life thought that all models 60" and below should have an Irvine 60 up front

[Bob Cotsford]

It would probably be fine with 1/2lb of lead removed! I do quite like my vintage models to float around, my Eros certainly does - 84" on an OS FS48 and it doesn't want to land, even at tickover. Nice for thermaling on a sunny day too.

[David Davis]

Bob, I agree with Gangster, get as much weight up-front as you can, I have the Rx battery under the engine in mine. Furthermore, the engine in mine is an HP VT 25 fourstroke which only just powers it. I've heard these engines described as, "Heavy as a 40, power of a 10!" but the extra weight is handy in the J 60's short nose. Once in the air, the model flies extremely slowly gaining a few feet on every circuit. My friends in my French club have never seen anything like it! .

As I have stated in previous posts, the Junior 60 was designed as a free-flight model so that providing the engine was running, the model would climb. With engines with a throttle it is possible to reduce the power output to such a degree that the model will fly straight and level or even to descend under power.

Picture of the fuel-soaked veteran below, warped wing and all but without the engine fitted.

[Bob Cotsford]

I think I may just strip this model out and do a bit of weighing, then do a fresh ground up installation and see what difference I can make to it's AUW. Winter is coming and I'm on long term sick leave so there's plenty of time. I'll leave the external 'patina' 'cos I can't be doing with a full on restoration but it'll be an interesting exercise to slim it down.

Any thoughts re gluing the tail on? I can't see any real need for it to be removable as I won't be stripping it down to carry on a pushbike and getting rid of the dowels and bands will save a few precious grams from the back end.

[ken anderson.]

here's the ne...1 version...OS 30 4/st...and 1/2 lb of lead in the nose....

ken Anderson...ne...1....... lead dept.

[Bob Cotsford]

1/2lb = 8oz=~240gm. Say a conservative 3:1 moment ratio for the effective position of the pushrods - wonder if the two 10mm pushrods plus 2mm threaded rods each end in mine weigh more or less than that 80gms? Might be I could save that much lead just by going closed loop! It will be interesting to see.

 

As near as I can make out on the kitchen scales the complete fuselage and tailplane weighs 4lb 11oz at the moment, so my target is to beat 4lb 3oz.

Edited By Bob Cotsford on 02/11/2016 11:08:14

[PatMc]

Before I converted my Jnr 60 to electric the OS25fp engine + nose weight was about 8.5oz [i.e. less than the weight of an OS26fs]. Most of it's ic powered flying was with an OS max 25 fitted with home made silencer, same weight when ballast added.
But my Jnr has the cg over 1" rear of the plan cg & is still a sedate flyer. I arrived at the cg by progressive incremental reduction of nose weight used for the first flights. IMO the cg position is virtualy optional due the tailplane area being so a large compared to the wing area.

Final ic engine used - OS 25FP.

Original OS max 25.

The refurb thread of my Jnr includes info on fixing the tail with a single small screw & ply tongue, [IMO better than gluing, neater & lighter than rubber bands & more secure than both] also info on pull-pull for rudder & elevators.

[Braddock, VC]

Irvine used to sell big brass prop spinner nuts that weigh about 80 grammes iirc, they go on an os 26 just fine and everything else with a 1/4 unf/6mm threaded prop shaft.

They put the weight exactly where you need it, it also acts as a flywheel to some degree, enhancing the slow running qualities, already great, of the little 4 stroke.

Glue the tail bits on and do closed loop for rudder and elevator and you may not need any more lead though with solartex it may be necessary.

Fitting the battery beneath the engine is one way of avoiding further lead though it can get oily unless you bite the bullet and modify the 26 fs by plugging the oil vent and drilling a small (1.5mm) hole from the rocker chamber into the inlet tract then sealing the rocker cover with hylomar or similar. You may have to richen up the slow running needle slightly to compensate.

You used to be able to buy rubber tyred, alloy hubbed wheels that helped as well.

Personally I've never felt the need to have wing bolts on mine but the one I've seen with them looked really neat.

As far as flying abilities of the J60, it's a marvellous way of learning how to thermal, some of my longer flights have been made after the engine cuts.

[Braddock, VC]

double post, oops!

PS I go along with patmc, c of g is very conservatively sited on the flair j60, wouldn't want to comment on the BB one.

FWIW my first J60, 1955 - 56 flew with an ED racer, covered in tissue and doped ( the plane, not the engine). The racer is no way a match for the os 26 fs. 

 

Edited By Braddock, VC on 02/11/2016 13:05:06

Edited By Braddock, VC on 02/11/2016 13:08:16

Edited By Braddock, VC on 02/11/2016 13:10:18

[Don Fry]

I used to have one, 20 size Magnum 2st, Slec 4 oz tank, mounted upright in the engine bay, then servos right at front in the cabin, battery underneath servos, close loops to the tail, clevises at the servo end. With that installation it needed no lead. Plan built, 3 lbs 12 oz, solartex covered. Very nice flier, about 40 minutes on the four once tank.

[Mike T]

Weight at the front is the key (and next to nought at the back of course). Mine has an OS40FS, Solartex'ed wings and fus., Litespan'ed tail. Servos, rx, tank and NiCad (yes, NiCad) all up front. No Lead!

The wheels are B&Q buggy wheels (NLA). A bit OTT perhaps, but they are light and the proportions are just right.

[Bob Cotsford]

Thanks for the comments. Pat, i like the bolt on tail, I have some 3mm inserts and nylon bolts spare from the Eros tail which is held on by 4 nylon bolts into inserts in the tailplane.

I doubt it will come down below 4lb, but I'd be happy if it lost 1/2lb or a shade more. Still, I have all winter to play with it.

[Bob Cotsford]

Thought I'd better drain the fuselage after the bung came out of the tank the other day, so while I was at it a bit of dismantling took place.

Pushrods - 2.3oz. 128 and 148 servos in the old Futaba plastic tray - 5.5oz - all behind the CofG.

Lead (between and on the U/C legs) 1lb 0.2oz. Bit of a daft place to put it!

Unfortunately despite what looks like a recent coat of Poly-C or similar the half former holding the rear U/C member is rotted, cracked and pretty moth eaten with some poorly positioned slots - previous wiring routes? I'll have to try soaking the nose in hot water and detergent tomorrow to see if the oil washes out. At least it's not bare wood. If there's anything clean enough to take glue it'll need a doubler adding to take the U/C. I don't think I need to worry about keeping the rework light! At least the aluminium hub balloon tyred wheels are quite nice.

[onetenor]

Why not try making a smaller lightly built tailplane.Say a 1/4 smaller. than standard. Should improve things John

[David Davis]

I made the tailplane on my first Junior 60 out of such heavy wood that I required one and a half pounds of lead in the nose to get the model to balance properly! It flew well in a wind mind!

I made a second tailplane out of lighter wood and was able to remove the lead entirely.

I don't think that a smaller tailplane is necessary, besides it would not look right!

[Bob Cotsford]

Posted by onetenor on 04/11/2016 04:55:30:

Why not try making a smaller lightly built tailplane.Say a 1/4 smaller. than standard. Should improve things John

too many other projects to spend much time on an airframe I only bought for the engine John! If anyone offered me say £10 for the bare airframe I'd probably take it. As it is I'll have a quick fiddle with it while it's raining, and if all else fails I've got a brand new ASP 28 2 stroke doing nothing. With a 10*4/5 that will take care of any lead related issues. Ain't no finessing taking place on this one

It looks to be the original KK design with narrow set hardwood bearers and I'm guessing it's had at least one previous makeover.

The airwheels would look good on my Eros, they may not stay on the J60.

Edited By Bob Cotsford on 04/11/2016 08:30:02

[Mike Etheridge 1]

HI MIke

I'm interested in your conversion of the E.D.Racer as I i'm thinking of doing the same to mine .

Could yo give some more details , are the exaust manifolds self made or commercial items , and how did you connect up the R/C carb .

Thanks Keith

I have only just seen this request Keith. In 1976 when I changed my Junior 60 to proportional radio witha Sanwa Mini 2 radio, I was able to buy an RC throttle and the exhaust stacks from Avicraft in Kent for the ED Racer. To buy them now would be difficult although it would be worth contacting Weston UK Ltd who have some ED spares as they bought the company. New pictures below:

[The real Ron Truth]

Ive flown vintage for years and the incidence set up is designed to be variable.

I can fly with the standard trim for calm days and add a shim to the tail LE if its windy to reduce the rate of climb.

Ive never shimmed the wing as its takes away some of the charm of the design and results in a sports model. Remember: Throttle is for altitude, elevator is for speed.

[PatMc]

Posted by The real Ron Truth on 05/11/2016 20:29:53:

Ive flown vintage for years and the incidence set up is designed to be variable.

I can fly with the standard trim for calm days and add a shim to the tail LE if its windy to reduce the rate of climb.

Ive never shimmed the wing as its takes away some of the charm of the design and results in a sports model. Remember: Throttle is for altitude, elevator is for speed.

Also remember : shim is for free flight, elevator trim is for RC.

[The real Ron Truth]

Pat,

I was always encouraged to have a model fly so the controls appear at neutral whilst in level flight . Adding elevator trim is fine in practice but always looks a fudge . Apart from that your wrote right!

[PatMc]

Ron, I don't see how elevator trim can be a fudge.

But I'd say that shimming is definitely an unnecessary fudge.

[Bob Cotsford]

My Eros needs quite a bit of down at full throttle (OS FS48), I'd be happy to adjust the tailplane incidence but it would mean rebuilding half of the fin so I settle for a throttle mix. Our RC versions are generally heavier than the free flight originals and 'adequately' powered so fly faster and that's why I think they need the extra down.

I've washed the interior of the J60 with hot soapy water, boiling water and meths but some of the wood still feels oily. Thin CA seems to stick to the balsa infills though so I can attach servo mounting rails ok. Luckily the former to which the rear U/C leg fixes seems clean enough to accept glue now I've cut the rot away. That will get a birch ply doubler epoxied to it - 3/32 liteply for an U/C attachment? Got to be Ben Buckle. Did you know that a grey Sullivan snake is well under half the weight of a 3/8" hardwood dowel - 15gm against 40? Guess it's getting a snake on the elevator seeing as the weather isn't playing ball this weekend. At this rate it will have to be a keeper, 'patina' and all.

[PatMc]

Actually Bob, I think our modern RC versions are often lighter than the original FF but we use motors that are much more powerful. Many of the original large FF usually only flew in calm or light wind conditions. In these conditions we could simply throttle back to fly like them without any need for the down trim in order to make headway.

OTOH some 1940's & 50's vintage types were actually launched to climb very steeply on excess power using a timer to cut the motor after a short run [typicaly 10 - 15 secs] followed by a long glide & the owner on a bike. In modern times I've seen a number of this type of model being flown puttering around nicely at low throttle with the proud owner convinced he's trimmed it to faithfully emulate the original.

 

Edited By PatMc on 06/11/2016 00:31:17

[Bob Cotsford]

Ah yes, a steep left turn spiral under power with the model trimmed for a right turn on glide. I'm still not convinced that our RC models are lighter though!

As for power, my original Eros that I inherited in 1968ish was powered by a McCoy 29 for single channel use, I'm sure that the articles I've found indicated an AUW of 4lb odd for the prototype as a freeflight model.  My current porker is more like 7lb (too much paint!) with an OS Surpass 48.  It's still good for a steep climb then half an hour of thermal sniffing though

Edited By Bob Cotsford on 06/11/2016 10:57:31