BB Junior 60 build - battery hatch

[Mike Hardy]

Having built the wing the next task is the fuselage. I plan to use the OS 1050 motor and a Turnigy Li-Po battery 3s 4000mAh dimensions 148 X 50 X 21 wt 503gm. Where should I place the battery hatch and any thoughts on a hatch design - there must be many on here who have already done this, so any tips would be appreciated.

Mike.

[Mike Etheridge 1]

I have two Junior 60 fuselages,one I built in 1962/3 with ED Racer power and the other I acquired from the Nationals 'swap meet' in about 2006 which has a 25 glow motor. Rather than a Lipo battery for electric flight I of course only needed to accommodate flight batteries. Originally the 1962 'New Junior 60' which is equivalent to the new 'Flair Junior 60' had an 'Ever Ready 1289' battery which wedged nicely between the formers that support(ed) the undercarriage at low level. I bolted the battery in with a ply strap arrangement. The bolts also held a ply hatch in place. This arrangement has lasted 50 years and currently holds a flat Ni mH battery in place. On the acquired Ben Buckle fuselage which is equivalent to the original narrow 1946 Keil Kraft Junior 60 the flight battery is just wedged with foam rubber in the same location but without any hatch.

Edited By Mike Etheridge 1 on 18/09/2012 12:25:38

[Mike Hardy]

Thanks Mike, they certainly look impressive!! I had not realised there were so many different 'Junior 60's' about, do they all relate back to Ben Buckle's design?

Mike.

[Steve Hargreaves - Moderator]

I think Mike (Hardy) is wondering how to secure the main flight battery in an electric powered version here Mike (Etheridge)....

[Steve Hargreaves - Moderator]

The Junior 60 dates back many, many moons Mike....1946 in fact when it was designed by Albert E Hatfull for KeilKraft. Keil Kraft closed in the early 80's & Ben Buckle re-kitted many vintage designs from this era....

The Junior 60 evolved into the Super 60 as radio controlled flight became more commonplace....

[David Davis]

I built a Flair Junior 60 for electric power several years ago in the days of NiCads and geared brushed motors.

I cut a slot in the firewall and attached a plywood box to the back of it, into which the NiCad slid. The box was well-ventilated with holes cut with a tank cutter and at the rear I incororated a Terry clip which gripped the NiCad while in use. In the event of a heavy landing the NiCad simply shot out of the front!

You couldn't use the Terry clip with LiPos but you could use the same box-and-slot arrangement.

Sorry, no photos, someone made me an offer I couldn't refuse years ago.

[Mike Hardy]

Thanks David I have heard about but not seen a Li-Po - is it a gel type of battery with soft walls? I like the idea of using a ply base and ty-rap the Li-Po to the base that is if they can be clamped.

Mike.

[Steve Hargreaves - Moderator]

Mike...you talk about a Turnigy Lipo in your opening post.....these are Lithium chemistry type batteries & are pretty much the mainstay of electric flight these days....very high energy density (ie a lot of power for not much weight). They are usually rectangular & lend themselves to being clamped to a flat plate very nicely.

If you are a beginner to electric flight then can I suggest some bedtime reading for you here ....

[Mike Etheridge 1]

Mike,

Steve has highlighted the issue that I had only to accommodate 4.5 / 6 volt battery packs to operate the radio in my Junior 60's and not a 9/10/11 volt flight pack to operate a brushless motor plus radio.

If you opt to use a lipo battery I am wondering how much lead ballast you will need to get the C/G right? ---both my Junior 60's have a 1/2 lb of lead in the nose(s)

The Keil Kraft 1955 'New Junior 60' had a wider fuselage than the 1946 model to accommodate the old valve radio and the HT and LT batteries needed in the past. My plan of 1962 shows this arrangement.

Best Wishes

Mike

[Mike Hardy]

Thanks Steve and Mike - it looks burning the candle tonight!!!

[PatMc]

Mike have you had a look at this thread showing Propaghandi's Jnr 60 build ? There's a photo of his battery hatch in the second page.

If you want to get the battery as far forward as possible you could try something like the method I used in my Magnattila but instead of leaving it open cover the front with a hinged hatch secured with magnets at the rear.

The Magnattila's cowl is cut away at the bottom so the battery is easily accessable but not obtrusive.

[John Payne]

Mike, if it of any interest, I have a J60 with a 2700 3S Lipo and the access hatch is on the bottom of the fuselage and is a simple affair. It is a ply plate which keys into a slot to the rear and has a servo arm secured with a screw at the front which pivots back over the ply plate to hold it in place. The battery is inserted from underneath and is held in by velcro on the battery and a ply plate secured to the fuselage structure between the original bulkhead and the first screen uprights. If that is unclear, let me know and I will take photos for you tomorrow. This arrangement allows the lipo to be changed quickly without any tools and moves the weight as far forward as possible. Cheers, John.

[Capt Kremen]

Mike H,

My two penny worth input ...

I've just renovated my late fathers 1946 plan Junior 60, converting it to electric from previous lives flying with Oliver Tiger diesel, OS 4-stroke glow among various ic motors used.

I fitted a brushless outrunner motor directly inplace of the i.c. paxolin motor plate and use a 3300mAh 3S LiPo flight pack held vertically just inside the 'cabin' behind the windscreen at the front. A few pieces of foam packing stop it rattling around or moving during flight.

No battery hatch needed, I don't find the removal of wing bands a chore to swap flight batteries between flights as it only takes a few minutes at most.

The model retains its original Solartex covering (including tailplane) and balances spot on 81mm from the leading edge without any additional 'dead weight' ballast. The C of G can go further back to 110 mm and still be OK if somewhat more responsive to control inputs.

Flight times of 15mins plus are easily achieved with plenty of capacity in reserve.

Edited By Capt Kremen on 18/09/2012 22:31:07

[Mike Hardy]

Thanks PatMc, John and Cap. Kreman. John if you could take a few pics of your battery set-up I would be grateful.

Whilst on here can anyone tell me how to form 1/4 sq. longerons!! I have tried steaming and soaking but they still remain firm and will not bend. I think this is another 'black art' trick peculiar to this hobby.

It would be advantageous for us beginners if a 'hints and tips' article could be published in the Mag covering this and other techniques. (Mods, pass on to the editor please)

Mike.

[Steve Hargreaves - Moderator]

Seek & ye shall find Mike......see here...

[Mike Hardy]

Thanks Steve - what would we do without you guys!!!!

[John Payne]

Mike, just picked this up, been out all day. I'll take a couple of photos in the morning and get them posted in. Cheers, John.

[David Davis]

Posted by Mike Hardy on 19/09/2012 09:24:11:

Thanks PatMc, John and Cap. Kreman. John if you could take a few pics of your battery set-up I would be grateful.

Whilst on here can anyone tell me how to form 1/4 sq. longerons!! I have tried steaming and soaking but they still remain firm and will not bend. I think this is another 'black art' trick peculiar to this hobby.

I've never had problems getting 1/4" sq balsa to conform to the shape of a Junior 60 fuselage but I once built a double-sized Vic Smeed Tomboy which has a much sharper lower fuselage curve and I couldn't get 1/4" balsa to bend to the shape regardless of how many pins I used . I solved the problem by making up the longerons from two 1/4"x1/8" strips.

[John Payne]

Hi Mike, photos as promised. Forget the backgrounds (!) and the fact this is a previously enjoyed, and modified, model.

This first photo shows the cover closed and locked in place. (it wasn't a servo arm is was a wire clamp to hold it closed)

The second photo shows the cover released.

The third photo shows the inside of that bay with the ESC and velcro to retain the lipo visible.

I have not had any problems with the battery coming loose in flight and it requires no great effort to remove the lipo for charging with no tools required. if you need any more help let me know. Cheers, John.

[Mike Hardy]

Thanks John, to make things clear to me - is the Li-Po mounted vertically along with the ESC? Is the nose aperture left open? The pics makes things a lot clearer. I am building the fuselage at the moment and plan to use a 4000mAh Li-Po for extra weight and longer flight times. Ii think a motor and battery pack will need to be obtained before the fuselage can be progressed.

Mike.

[John Payne]

Mike, glad to help. The nose aperture is left open as originally I used that to get in a 10 cell nicad pack, in the same way as PatMc does in his post. I found it awkward as the motor/ESC wires got in the way. The aperture now allows cooling air into the fuselage for the lipo and ESC. The bigger lipo is a good idea as I still need around 7 ounces of lead in a hatch above the motor to bring the CG to the correct position (very important!). Even with all this weight it still outperforms some of the gliders on a good day. I now use it as a camera plane and it flies well even with a digital camera mounted on the front. If you need any more info let me know and I will catch up later this evening. Cheers, John.