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Aug 17, 2019, 05:53 PM
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Watts New F5J mK2, CNC shortkit build


The Watts New F5J is an F5J entry competition balsamodel (uses a carbon boom) designed and built by Brian Austin in 2014. He's AKA BOF Essex here on RC.groups.com. Check links below for his builds. He won the eastern F5J league in Great Britain for three consecutive years, in 2014, 2015 and 2016 with the Watts New. His plans are handdrawed and then digitalized in 1:1. There exist a mk1, mk2 and a V-tail version. of the Watts New. Short kit is available from glidergear.com.au (Mr Greg Potter)

Specifications:
3,8m wingspan
AUW from 1,7kg-2.2kg (All Up Weight depends on lightness of balsa parts, reinforcement choices, electronics etc)
Propeller: Aeronaut CAM Carbon 16x8
Motor: Hacker A20-6 XL 10-pole EVO 2500kv 4,4:1 (130g)
ESC: Not decided on yet. 55A minimum.
Battery: from 850mAh 3S up to 1300mAh 3S
2xAileron: KST X08 (8g per servo)
2xFlap: KST X10 mini (23g per servo)
1xElevator: KST X08 (8g per servo)
1xRudder: KST X08 (8g per servo
Carbon boom from a CLM Pro #130 fuselage kit. (Might change to something else due to this particular carbon boom being 2 cm shorter in lenght than the plan, and a bit narrow at the tail end.

The hacker A20-6 XL EVO 2500KV paired with an 16x8 propeller should result in about 375W.
Watts New Mk2 has a one (Edit: two inches) inch longer nose than the mK1, which enables a lighter battery choice (enabling a 850mAh 3S in mk2, from 1300mAh 3S in mk1)
I divert from original plans with a pull-spring on the rudder. The rudder servo will be placed in the fuselage under the wing with kevlar thread going through the carbon boom to the rudder. As per plans, the elevator servo will sit beneath the horisontal stabilizer, inside the pylon.

Plans and instructions were bought from Brian Austin last year for 25 GBP through a PM here on rcgroups.com (his user name: BOF Essex).
I bought the short kit for wing ribs+balsa spars (about 90AUD), horisontal and vertical stabiliser (about 40AUD) and balsa fuselage (about 75AUD) from Mr Potter at Glidergear.com.au in Australia. The total costs of these short kits (exluding VAT and shipping) was approximately 215AUD, which I think is a lot of sailplane for the money.

Do keep in mind one still have to source for lighweight balsasheets for the wing, thin fibreglass cloth for fibreglassing the wing, carbon strips for the wing spar and tail, carbon tow for reinforcement of fuselage's inside and the servo trays in wing, carbon rod and aluminium tube for wing joiners (Edit: or better, scratch build the joiners), screws for wing and horisontal stabilizer, just to mention the most important hardware.

You can check out Mr. Austins build threads here:
Watts New mk1 (2014) and mk2 (Longer nose + reinforcements, 2016):
https://www.rcgroups.com/forums/show...atts-New/page1
Watts New "Swansong" (V-tail version, 2017) :
http://www.esoaring.net/forum/viewto...st=0&sk=t&sd=a

Other builders:
https://www.rcgroups.com/forums/show...tt-s-New-build
Last edited by Kristian1987; Aug 23, 2019 at 03:54 PM.
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Aug 17, 2019, 06:13 PM
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Horisontal stabiliser has been built over the course of two evenings using Titebond 3 waterproof wood glue and 30 min epoxy. Elevator has been sanded to shape.

I overlooked the carbon strip reinforcement around the center part. So I had to saw open four ribs and the center, glue in carbon strips with epoxy and glue ribs back in again.

Next up is building the vertical stab and rudder. After that I will build the fuselage and ending with the wing after that.

I'm building this model at my local RC-club, which has a new and very nice building room. I'm building on flat styropor-plates, otherwise used for isolating buildings.
Last edited by Kristian1987; Aug 17, 2019 at 06:22 PM.
Aug 17, 2019, 07:14 PM
What you looking' at fool!
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Aug 18, 2019, 03:16 PM
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Essex BOF's Avatar
Quote:
Originally Posted by Kristian1987
The Watts New F5J is an F5J entry competition balsamodel (uses a carbon boom) designed and built by Brian Austin in 2014. He's AKA BOF Essex here on RC.groups.com. Check links below for his builds. He won the eastern F5J league in Great Britain for three consecutive years, in 2014, 2015 and 2016 with the Watts New. His plans are handdrawed and then digitalized in 1:1. There exist a mk1, mk2 and a V-tail version. of the Watts New. Short kit is available from glidergear.com.au (Mr Greg Potter)

Specifications:
3,8m wingspan
AUW from 1,7kg-2.2kg (All Up Weight depends on lightness of balsa parts, reinforcement choices, electronics etc)
Propeller: Aeronaut CAM Carbon 16x8
Motor: Hacker A20-6 XL 10-pole EVO 2500kv 4,4:1 (130g)
ESC: Not decided on yet. 55A minimum.
Battery: from 850mAh 3S up to 1300mAh 3S
2xAileron: KST X08 (8g per servo)
2xFlap: KST X10 mini (23g per servo
1xElevator: KST X08 (8g per servo)
1xRudder: KST X08 (8g per servo
Carbon boom from a CLM Pro #130 fuselage kit. (Might change to something else due to this particular carbon boom being 2 cm shorter in lenght than the plan, and a bit narrow at the tail end.

The hacker A20-6 XL EVO 2500KV paired with an 16x8 propeller should result in about 375W.
Watts New Mk2 has a one inch longer nose than the mK1, which enables a lighter battery choice (enabling a 850mAh 3S in mk2, from 1300mAh 3S in mk1)
I divert from original plans with a pull-spring on the rudder. The rudder servo will be placed in the fuselage under the wing with kevlar thread going through the carbon boom to the rudder. As per plans, the elevator servo will sit beneath the horisontal stabilizer, inside the pylon.

Plans and instructions were bought from Brian Austin last year for 25 GBP through a PM here on rcgroups.com (his user name: BOF Essex).
I bought the short kit for wing ribs+balsa spars (about 90AUD), horisontal and vertical stabiliser (about 40AUD) and balsa fuselage (about 75AUD) from Mr Potter at Glidergear.com.au in Australia. The total costs of these short kits (exluding VAT and shipping) was approximately 215AUD, which I think is a lot of sailplane for the money.

Do keep in mind one still have to source for lighweight balsasheets for the wing, thin fibreglass cloth for fibreglassing the wing, carbon strips for the wing spar and tail, carbon tow for reinforcement of fuselage's inside and the servo trays in wing, carbon rod and aluminium tube for wing joiners, screws for wing and horisontal stabilizer, just to mention the most important hardware.

You can check out Mr. Austins build threads here:
Watts New mk1 (2014) and mk2 (Longer nose + reinforcements, 2016):
https://www.rcgroups.com/forums/show...atts-New/page1
Watts New "Swansong" (V-tail version, 2017) :
http://www.esoaring.net/forum/viewto...st=0&sk=t&sd=a

Other builders:
https://www.rcgroups.com/forums/show...tt-s-New-build
A couple of points. The nose length increase should read 2 inches(50.8mm) rather than 1 inch. I always build the tailplane with the elevator in one piece, then cut it free when shaped to section, this is repeated for the flaps & ailerons, built as a wing, glassed then cut free & inner facings glued in by insetting into the facing joints.
My experience of Titebond has not been good, as I found it became brittle and joint would fail. Maybe me, but do not use it now.
I made my own 4 degree joiners, from carbon fibre, in a mould . If using a straight joiner make sure you can achieve the correct dihedral angle, as the wing is not that thick to take the angle of the tubes. Either way, I use a one piece of tubing, that is slid into both panels that are going to meet, so as the match when coming together. This is cut through between the two panels , having left a small amount to be flushed off, after having glued the ply facing ribs, onto the balsa facing ribs
Last edited by Essex BOF; Aug 19, 2019 at 10:32 AM.
Aug 26, 2019, 08:28 PM
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Thank you Brian, I've edited in your corrections to the first post.

I managed to put in almost five hours today on the vertical stab and rudder. 30 min Epoxy was used where the carbon strip was sandwiched for the leading edge of the vertical stab. And Titebond 3 for the balsa parts. Tools used mostly today was a small flat tungsten file and my trusty 30 cm tungsten sanding block, which makes sanding balsa, carbon and ply to shape a quick and easy job.

The CNC short kit for the fuselage will arrive by mail in a week or two, so there might not be too much activity here until then.
Aug 29, 2019, 03:23 PM
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Interesting seeing the build using laser cut parts which I did not have. I built the rear surfaces using parallel wood for the ribs, to aid the build, then shaped to section after. The fin was built in my hands using cyno , for glueing. The vertical stern post was made up of the lamination of carbon sheet, untapered at this stage, The bottom rib that is glued to the boom with stern post, is glued to the SP making sure it is square position wise, the leading edge of fin, is offered up to the SP & bottom rib, checking for square and parallel to the SP when viewed from the front. Mark the positions of intermediate ribs, which are the added, to complete item. Rudder is a repeat in an opposite view. Couple of pictures showing the fin with carbon in lay on L E
On the Mk 2 version, I laminated .1 carbon sheet between two 2 layers of 2mm sheet. This firms it up and gives a good guide when sanding to section.
I also assembled the fin and tail plane onto the boom, as an assembly before setting it up to attach to the main pod.

This is not to tread on other building of the model, that others may take up, just as a guide to help. The laser cut parts looks as they greatly simplify the construction, so can be the way to go.

Keep us posted Kristian
Sep 04, 2019, 03:35 PM
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Thread OP
Thanks for the input Brian. I have managed to put in two to three evenings worth of work the last days, and also made some trips to a couple different hardware stores to get some items needed; carbon tow, aluminium tube, M4 screws plus nuts, balsa strips, balsa and ply plates etc.

I've aso been working simultaneously on another F5J project the last week: Höllein Inside F5J. It's the second time I'm building an Inside F5J. this time its a lightweight project, trying to get it down to 950g from 1100g, Just a delight to build that model by the way, a perfect beginner kit.

So I laminated the fuselage sides (balsa and ply) with Titebond 3. Had to watch out a bit for warping, I used any weights I could find to keep everything flat while glue dried. Used thick CA to glue in the longerons/frames for the fuselage sides. The keel has been glued to the two formers it attaches to. I had to cut to shape a bit in one of the CNC formers, but nothing drastic. Otherwise there's been some sanding and filing, quite a bit use of dremel to make parts fit and go together.

Tomorrow I will probably glue the fuselage together and hopefully start on the pylon for the horisontal stabilizer and aligning the tail feathers. I think I have all the hardware now to get that stuff going. I decided to use the boom from the CLM-pro #130 set I had originally bought for this project. I will extend the boom one cm at the narrow end with some balsa type of plug or something, as the boom is one cm short of the Watts new plans. I also made the motor firewall today. Used some paper to trace out the three screw holes for the Hacker motor and transferred those onto the ply firewall. Looks like center was achieved.

And yes, I did manage to glue the frames/longerons on the ply side of the fuselage, which was the outside of the fuselage. Luckily I had bought two fuselage short kits, so I just laminated one more side from the other set and continued. The ply side will be on the inside of this model. No excuses for such a mistake. Well, I've been sick from work with a nasty cold, so guess I have an excuse after all.
Last edited by Kristian1987; Sep 04, 2019 at 06:45 PM.
Sep 05, 2019, 10:45 AM
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Essex BOF's Avatar
Hi Kristian
I could have sent you a PDF file for the motor screws, as I usually draw them on a CAD drawing & print full size, then paste onto a fibre glass PC board, as the motor mount and 38mm dia. Glue this onto the F1 former, then use this as a jig to drill holes, for motor and the outside 38 mm as a template to shape the nose.
I always mark the inner side of the sides, so as not to end up with 2 of the same orientation, as happened to you.The ply doublers can be used to cut the 3/32(2mm) balsa side's, so using an impact adhesive, they can be bonded onto the sheet, then cut around as a template, so saving trying to line up to a cut balsa side.

Found searching E Bay can throw up parts needed, such as screws carbon flat strip for spars.
If you get stuck, message me and will advise on things that may not be clear.

BTW I do not think the 1 centimetre loss on the boom length will make a lot of difference really.
Brian
Last edited by Essex BOF; Sep 06, 2019 at 03:08 AM.
Sep 15, 2019, 02:54 PM
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My fellow RC buddy is also building a Watts New F5J


Just a quick update on my friend's Watts New build. He started his build in September and we're actually building our Watts news side by side in our local RC clubs buildingroom for the time being. So hopefully we learn from each others experience as we're progressing in the process.

As you can see he has the long #133 fuselage from CLM-Pro.com. He is using the all-flying horisontal stabiliser option. Tail feathers and wing parts are Watts New CNC'ed parts from glidergear.com.au. All up weight on #133 fuselage with tail feathers and all electronics inside was about 600 grams.

My friend is going a radical route on the wing build as he wants it to be a lightweight floater, hoping for 1,3-1,6 kg AUW. So he is going for just a D-box with oracover. Flat balsa strips along the top an bottom sides of the ribs to support the oracover. Wing spar will be a carbonfibre square tube 10mmx10mm as seen in one of the images. Seems very stiff. The square tube is hollow, with an 8mm round hole throughout the tube. Wing joiner is planned to be an 8mm steel/aluminium rod, angled at 4 degrees and which will fit inside the square tube which acts as a wing spar and joiner combined.

The order of operations on my friend's wing build here is based on his experience and intuition. It is very different from Brian Austin's tried and proven method, which I will follow in my own build. As you can see he has glued in the ribs first to the LE and bottom spars, and he now has to clip out a rib length of 10mm from the mid section of every rib to allow the square carbon Fibre tube 10mmx10mm wing spar to fit in between all the ribs. Then he will sand the LE to shape and complete it with sheets of balsa for a D-box.
Last edited by Kristian1987; Sep 15, 2019 at 04:21 PM.


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