WOT4e flying v Junior 60 (with elec conversion)?

[911hillclimber]

Interesting.

This model was built and never flown and was full of Futaba radio servos etc.

I scrapped an FMS Kingfisher and re-used the servos from that, mounted in the tail similar to yours but 'hidden' under the tail plane and long

wires back to the Rx

I was not sure that was lighter, but easy conversion and I knew it would all work with my DX6, the main reason for the change over.

 

I've ordered a big box of weight strips.

Will look at the CofG articles too as this will make quite a difference to the nose weight mass.

 

Looks like the elevator movement is about 15 deg up and 12 deg down.

[Andy Gates]

911,

 

If you have  put standard size servos in the tail it will need LOTS of nose weight. Each standard servo weighs about 35g.

The photo with the servos in the tail are small servos about 10 - 17g each.

Either way, I would fit the servos in the fuselage as far forwards as realistically possible then use push rods or snakes to move the surfaces. This way the amount of weight required in the nose will drop and the plane will be much more pleasant to fly.

 

Good luck

[911hillclimber]

That was the conclusion I had almost reached this afternoon as the only way to shift weight to the front.

I think your suggestion will make life better.

On other builds I've made the classic wire/balsa runs from servo to surface links, possibly as light as you can make such runs.

 

With the snow on it's way, could be a good time to change things round.

[john davidson 1]

Nose ballast is literally dead  weight. J60 was my first rc plane 40 years ago and I knew enough even at that time to extend the engine bearers so ballast was not needed, Why has no one mentioned this simple   mod ?

[payneib]

21 minutes ago, john davidson 1 said:

Nose ballast is literally dead  weight. J60 was my first rc plane 40 years ago and I knew enough even at that time to extend the engine bearers so ballast was not needed, Why has no one mentioned this simple   mod ?

Probably because the engine bearers are already well built in to the business end of the fuselage, and it's not worth cutting up a perfectly good airframe when they fly perfectly well with a bit of a ballast in the nose. 

[Andy Gates]

If you are really getting weight critical, then closed loop connections to the rudder will be lighter still and more in keeping with "vintage" machines

[911hillclimber]

This plane was all built and drilled for an IC engine but the engine etc was never installed, hence never flown.

The control links were not in the plane, just the servos on a rough ply plate.

 

As it is all covered (rather well) I don't want to cut open holes other than a breather hole to help cool the ESC.

I was/am hoping such a hole will allow threading the snakes through.

 

I've just ordered 2 x 36" snakes with fittings from 4Max. 36" will get me from the tail surfaces to the prop, so I can get the servo's right forward and also mount the 3S 2200 battery vertically right up against the bulkhead so weight will be as far forward of the CofG as I can get it.

 

Must admit, the servo's taken from the foam plane do seem very small, but the change around will be better in the long run and as said, remove the need for much of the additional nose weight.

 

Quite like this type of tinkering on these planes, so all good in my book.

 

+++++++

Thought I would own =up and say I have just looked deep down in the fuselage and the two outer tubes for the snakes are all glued in place inside the balsa frame... What a bonus! Just need to feed the steel wires in and terminate to the surfaces and servos once mounted far forward.

Edited January 3 by 911hillclimber

[kc]

It would be so much better to move the Lipo further forward to achieve CG rather than add lead to the plane.   Even if it changes the looks a little and offends the purists it will produce a better flying plane.    Worth trying a 'lash up' first to determine how much further forward the Lipo (and / or the motor ) needs to go.

Edited January 3 by kc

[kc]

23 minutes ago, 911hillclimber said:

feed the steel wires

Do you mean the thin closed loop wire ( fishing trace stuff ) or heavy Bowden wire?   Closed loop needs two wires to each surface ( Push and Pull ) while snakes need just one.    The outers for snakes might not suit the plastic inners as standards vary- need to check if they would run smoothly and not bind.

 

If you make any changes it's worth remembering the old trick -- before you pull anything out of the fuselage tie or tape a string to it to pull the new wire/snake etc back in.   Much easier!

[Don Fry]

Thin nylon covered fishing stuff, mine is 15 kilo. Other weights exist, but a mate gave me a reel half a lifetime ago, and it’s still going.

[J D 8 - Moderator]

3 hours ago, kc said:

Do you mean the thin closed loop wire ( fishing trace stuff ) or heavy Bowden wire?   Closed loop needs two wires to each surface ( Push and Pull ) 

  It's pull and pull, wire can't push. On my Veron Cardinal they are just nylon fishing line, and are external from just behind wing.

[Phil Green]

5 hours ago, Andy Gates said:

The photo with the servos in the tail are small servos about 10 - 17g each.

They're 8.5gm servos, Emax ES08A:

 

[PatMc]

5 hours ago, john davidson 1 said:

Nose ballast is literally dead  weight. J60 was my first rc plane 40 years ago and I knew enough even at that time to extend the engine bearers so ballast was not needed, Why has no one mentioned this simple   mod ?

Because it's not necessary. The cg shown on all modern copies of both original plans are estimates made by the whoever drew the particular copy. The original KK plans of both versions of the Jnr 60 doesn't show or mention the cg position. As mentioned by Phil Green in a post yesterday my model now has the cg @ around 40% (It's actually about 1.3" behind that shown on the Flair version plan). It might have ended further back still but since it flew (flies) with no vices with that particular balance there was no point changing it.

 

[PatMc]

BTW Phil, I hadn't seen that RCG post until today - a bit too late to answer it now but it does agree with my opinion on why so many have problems with vintage models. IMO the plan revivalists should only make changes they can justify or at least point out where they have made any changes & why.

[Christopher Wolfe]

10 hours ago, Andy Gates said:

If you are really getting weight critical, then closed loop connections to the rudder will be lighter still and more in keeping with "vintage" machines

 

I find it quite interesting to see the 'modern trend' is to add servo's at the rear end of a vintage model aircraft.

 

There is no respect for the original designer or the aerodynamics involved when the objective was to achieve a stable Free Flight model and adding a radio was a luxury that could be afforded by few in the frugal days after WW2.

 

Closed loop cable connections are ideal for this type of model, keep the weight of servos and batteries close to the CG.

 

[David Davis]

I must agree with Christopher Wolfe and question the use of rear mounted servos in a model with such a short nose as the Junior 60.

 

I have recently completed the build of a Galaxy Models "Mystic." This is a large sports-aerobatic model fitted in my case with a Laser 155 engine. I assumed that by having an oversized fourstroke in the nose that I could easily fit two standard size servos to the rear and still achieve the correct c of g. Initial assembly showed that the model was tail heavy so I moved the servos to a more conventional position and all was well. Bear in mind that the Mystic does not have a short nose.

 

As I've said above, I plan to build Junior 60 over the next three months, cover it in tissue over doculam and power it by an OS 15. This will be my third Junior 60 and I intend to build it as light as possible. I have some small servos set aside for the project but may well use standard servos as far forward as possible given the need for nose weight on the Junior 60.

 

911 if I were to build an electric powered Junior 60, I would mount the LiPo vertically behind the F2 former and build an access hatch into the underside.

[911hillclimber]

Yes, and that negates the need to un-band the wing every time to change the battery.

 

Plan now is to action all these excellent suggestions.

 

Current FMS servos to the very front, either side of the vertical LiPo 3S 2200 battery, bottom hatch install.

Snakes to the rear surfaces.

Steel or brass prop nut

Minimal I hope nose weight dropped into the engine nose box.

[Phil Green]

7 hours ago, Christopher Wolfe said:

I find it quite interesting to see the 'modern trend' is to add servo's at the rear end of a vintage model aircraft.

I wasnt aware of any modern trend, I simply had to fit the model out at very short notice and lightweight servos were the easiest and quickest option. 

 

7 hours ago, Christopher Wolfe said:

Closed loop cable connections are ideal for this type of model, keep the weight of servos and batteries close to the CG.

 

Yes they are if you have time to install them, I have done that on other models. Most of my models have a single torque-rod to the rudder which would have been the most 'period appropriate' method.  Although it was necessary to get that particular J60 ready at very short notice, its been happily flying in this configuration for 7 years now, with only 80 grammes of tyre-balance weights up front.

 

7 hours ago, Christopher Wolfe said:

There is no respect for the original designer ...

 

Now why on earth would you say that. I have massive respect for Albert Hatfull and designers of that era, in fact one of our annual S/C & Retro R/C events was themed in his name.  At least mine fly on reeds,  a method appropriate to the J60 era, presumably yours would be proportional?

I'm going to withdraw from this particular discussion now, I've had several Junior 60s and simply thought I could contribute, theres no need for personal jibes about respect  :)

Happy New Year

Cheers

Phil

 

[911hillclimber]

I'm sorry this has generated a some discord.

 

I think I'll come back when I have a 'result' and can show what I've done and the weights needed to balance the plane around the wing spar.

 

Certainly the experienced flyer at the Club's field will only buddy Tx with me if he is happy with the balance which has been on the deepest of the wing section on my foam models, so on this design the spar which is 70mm from the leading edge.

That will be the aim: to CofG at 70mm knowing I can balance either side of that but be nose heavy if anything.

 

I'll add some pics if I can remember how to post on this forum.

Edited January 4 by 911hillclimber

[David Davis 2]

When the model is complete you'll have an aircraft which is a delight to fly even when you are capable of flying much more demanding aircraft.

[Christopher Wolfe]

17 hours ago, Phil Green said:

I wasnt aware of any modern trend, I simply had to fit the model out at very short notice and lightweight servos were the easiest and quickest option. 

 

 

Yes they are if you have time to install them, I have done that on other models. Most of my models have a single torque-rod to the rudder which would have been the most 'period appropriate' method.  Although it was necessary to get that particular J60 ready at very short notice, its been happily flying in this configuration for 7 years now, with only 80 grammes of tyre-balance weights up front.

 

 

Now why on earth would you say that. I have massive respect for Albert Hatfull and designers of that era, in fact one of our annual S/C & Retro R/C events was themed in his name.  At least mine fly on reeds,  a method appropriate to the J60 era, presumably yours would be proportional?

I'm going to withdraw from this particular discussion now, I've had several Junior 60s and simply thought I could contribute, theres no need for personal jibes about respect  🙂

Happy New Year

Cheers

Phil

 

Oh dear, I was not trying to offend anybody and am sorry that you took this personally Phil.

 

I have the greatest respect for people who actually build and fly classic designs and especially the single channel adaptations using 2.4GHz equipment.

 

My reply was maybe poorly worded and so I apologise, it was not intended as a jab at yourself or anybody else.

 

What I was trying to point out is that with the short nose of many older designs there can be quite a large moment arm with the tailplane a long way behind the CG so that even a few grammes at the tail end is magnified by the moment arm thus requiring extra weight at the nose to compensate.

 

Like others, I find that a simple closed loop system using fishing trace or Spiderwire results in a lightweight model with all the 'heavy' bits up front.

 

Not all my models are proportional, they are mainly Free Flight actually so I well understand the importance getting everything correctly aligned and balanced of but I still have a few Elmic escapements and OS single channel relay/actuators.

 

My first successful R/C model was a s/c KK Super 60, Elmic escapement, first flown at Wanstead Flats over 50 years ago using McGregor bang-bang equipment.

 

May everybody have a great new year.

 

* Chris *

 

 

[911hillclimber]

The 're-conversion' is going (too?) well.

The ESC and it's wire lengths (not generous) sort of dictated the layout.

The hole from the servo space by the engine bearers has been enlarged to 20 x 15 mm and the motor leads can pass into the engine bay well with some length to connect and the excess tucks away down into the engine bay side cheeks,

The lead to the battery and Rx are now inside the servo bay and playing at being the plane's dash board.

 

The cooling I hope will be ok....

 

The battery now stands vertically and is in-between the engine bearers and sits on the sheet balsa base by the under carriage and neatly protrudes in the right place to link to the ESC and Rx yet right up (bar 5mm) to the rear of the bulkhead of the engine bay. I know this means removing the wing to change batteries, but no big deal.

 

Having removed the attempts of the previous builder(s) of the plane i have the original servo mount holes deep into the servo bay.

Using the FMS servos (which are a mighty 10 grams with horn and 100 mm long leads) this servo platform of the original needs to come up a good 20mm to align the servo horns to the existing  snake tubes and avoid as much as possible any 'out-of-straight' passage of the wires from the horns to the entry of the snake tube.

 

I can also site the servos 10mm aft of the C of G, so not too bad.

[911hillclimber]

Have to stop now while the snakes arrive soon I hope.

 

Everything is in place now to move the weight forwards as above.

 

The conclusion of all this is at 70 mm spar position from the leading edge the additional nose wight is 290 grams to be added, that's 15 Oz or nearly a pound!

 

Nothing I can see to make this less, so it will have to be so.

 

Bit dissapointed, but watched a YouTube video of a similar plane and R/C electric on a new build Junior and the flyer had to keep strapping lead strips to the nose to get it to glide 'flat' and fly. He seemed a very experienced flyer.

 

Pics to follow when all done and cleaned up.

[David Davis 2]

One pound is still eight ounces less than the weight carried by my first Junior 60!

 

No chance of fitting a bigger battery? A closed loop system on the rudder would save a little weight too.

[911hillclimber]

That's good to read!

Being used to a foam WOT4e this plane feels like a lead weight, but I flew a 4 stroke/ balsa version last year (plane my buddy was flying) and the plane few really well in the 10 mph gusts typical of our air field on a very good day.

 

I have a set of 4 x 3 cell batteries that fit all the planes I have somehow amassed over 4 years, but doubt i can find room now for a fatter battery, I guess a 5 cell 2200 is longer than the 3 or probably larger in all dimensions.

 

Today, I think I'll tidy the plane up and get the radio all working, drill the prop to 8 mm dia shaft and machine the brass/steel nut which will add yet more balance, "every little helps".