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Member postings for Martyn K

Here is a list of all the postings Martyn K has made in our forums. Click on a thread name to jump to the thread.

Thread: 20 cc V-twin two stroke
14/10/2018 22:20:07
Yes. So will I. Good luck.

Ps. Do you have a spare dynamix carb with that box of bits?

Edited By Martyn K on 14/10/2018 22:20:53

Thread: K5682 - Martyn's Fury
14/10/2018 22:14:50
It's the way i build my gliders tony. Makes for a strong and reliable joint. Its not easy to describe - and it is a bit of a faff but I think worthwhile persevering with

Edited By Martyn K on 14/10/2018 22:15:25

14/10/2018 21:12:24

....continued

The spars are 1/4" wide. The idea is to have carbon fire (5mm diameter) stubs permanently fixed into each wing half. These fit perfectly into 1/4" OD brass tube. The stubs and tube fit into one bay each side of the wing break, the stubs therefore are 2 bays long.

wing3.jpg

So for the centre, a dummy spar was created that holds the tube in a curved cradle, so it is parallel with the spar - i.e point straight out.

wing4.jpg

Its a bit of a faff getting it to fit and leave enough space for the upper spar which will encapsulate the tube so it is supported top and bottom. It took me 4 or 5 hours to get all 4 correct. 2 front and 2 rear). The tube is aligned just under the upper spar, not centrally...

The epoxy was gently heated and the top spar and other ply B5/B6 in the centre was added

wing6.jpg

then it was all clamped up while the PVA dried. The resin can take its time because it isn't going to move

The CF rod in the outer will need to drop about 3mm to accommodate the 4 degrees dihedral in the lower wings (2 degrees dihedral in the upper wing).

So pack up the wing and cut a length of carbon fibre rod and insert into the tube.

wing10.jpg

Align the wing so that its not swept back or forwards. You will need to pack up the wing tip packing to line up the front spar. Carefully sand the spars and TE (LE not fitted yet) until you get a good joint and secure into place - I used a mix of pins and weights. I then added the dihedral rib breaks with the inner (centre section) ribs vertical - not canted at 2 degrees as you may expect. I had to cut a couple of extra ribs for this so used some nice 3/32" balsa for the two inner ribs in the outer panel.

wing11.jpg

The next job was to cut wedged in balsa to support the CF rod

Its a 3mm drop so quite easy to sand that down from a piece of 1/4 x 1/8 at the rear and 1/4 square at the front

wing9.jpg

Wedges not shown on this photo but its clear where they will go.. (Hopefully)

Finally glue and clamp up and keep your fingers crossed that no epoxy has seeped into the tube...

wing12.jpg

This photo shows the upper wedge fitted before the rear top spar was added afterwards. You can also see the centre ribs fitted. These will have ply cap ribs fitted.after the wing has been sheeted

More to come

Martyn

14/10/2018 21:12:06

Getting severe withdrawal symptoms watching all these tail surfaces and fuselages being built so I thought that I had better make a start.

My Fury will have a few minor changes. I was at our local club (SCRCS) a week or so ago and watching Grand Maestro, the Honourable and Venerable Gordon Whitehead flying his lovely DH82a Tiger Moth. When he came to pack it up I was astounded on how easy it was to de-rig and dismantle. The secret of course was the 3 piece wings held in place by the active rigging. I was already toying with the idea of splitting the wings - but primarily for storage so the scene had been set. I just had to make a few tweaks to the Fury design

While I was still thinking this through, I started on what appears to be the easy bit, the lower wing.

win13.jpg

Every project has to start somewhere

The 1/16 balsa TA was cut and a strip of 1/4 x 1/16 spruce added to the upper surface (instead of balsa. I have gone for spruce to add a bit of ding resistance. By the time it has been sanded to profile you wont notice the weight.

I also made my first mistake - didn't take long. I didn't lift the underside spar to allow for the 1/32 packing to help keep the covering off the spars. Danny spotted this almost straight away, but I was puzzled why I missed it. The shop bought 1/4 x 1/8 balsa strip was a good deal thicker that 1/8 so when I seated the ribs, they fitted perfectly - no alarm bells raised.

Blindly carrying on and feeling pretty pleased and mentally noting how well everything fitted

wing14.jpg

 

A few pointers. The rear part of the rib sits flat with the lower spar (supposed to be) packed up by 1/32". The front spar is about 6mm in mid air and will need spacers. I didn't have the thick spar problem as this one came from a different batch.

wing15.jpg

When I cam to fit the wing tip, the ply and balsa parts fitted great. However, the tip ribs appear to have the slot cut in the wrong place. You can see from the plan. The cut away should be over the ply inner perimeter. It was easy to trim back about 2 or 3mm but that has made the front of the rib short. mmm I didn't think that through as I cut back and glued it into place

wing16.jpg

So you can see where I was up to on Friday evening when I packed up.

I had a BMFA council meeting in Leicester yesterday, so only an hour in the shed before I had to leave

Started work on the centre section.

wing1.jpg

B5 & B6 are cut from ply and hacked into 3 pieces.

The front and rear of the ply boxes glued into place with the intermediate part of the ribs

wing2.jpg

Likewise the outer parts are glued onto the end of the wing half. Note the upper spar is just temporarily inserted while the glue for the brace dries.

 

 

Edited By Martyn K on 14/10/2018 21:13:23

Thread: Rearwin Speedster 6000
12/10/2018 14:40:35
If the woktop is flat then it will be ok. Make sure you go up to the wall as stuff will fall down the back. Just tack the corners so you can remove it if you dont like it. Mine last about 2 to 3 years.

You can see from tne photo that i put an offcut of carboard to protect it when its being used as a work area. Its not a workbench though so you may need to think through your working procedures

Martyn
11/10/2018 18:36:32
Thanks both

I love plasterboard for building on. Its cheap and easy to replace when it gets damaged. Which it will. I just tack it to a pine board that has lateral braces underneath to prevent it bowing.

I have 3 building boards. Daddy is 2m long x 500mm wide, mummy is about 1.4m x 300mm and baby is about 750mm x 300mm.

All are plasterboard on pine

Edited By Martyn K on 11/10/2018 18:37:08

11/10/2018 16:26:12

A bit of progress in the last couple of weeks

Wing has (mainly) been built. All very straightforward

wing1.jpg

The only real highlight is that I have used 0.006" unidirectional carbon cyano'd to the top and bottom of the spars.

wing2.jpg

Wingtips laminated around a cardboard template with cling film to protect the wood. No carbon in these tops they are strong enough without additional reinforcement

wing3.jpg

The aileron inlays were added after the wing was assembled, cutting slots into the ribs with a razor blade and gently teasing out the slot. Quite time consuming but it does mean that the slots fit the wood exactly. The ailerons have been separated except for the TE...

wing4.jpg

The other wing.. The LE sheeting is 1/32" balsa, sanded thinner..

wing5.jpg

I puzzled over how to join the wings. On the 6000C (this version and the C stands for Cirrus), this version does not have the clear plastic roof which means I can hide some structure.

The wings have rather think end ribs - this was intentional as I envisaged I would use these structurally rather than just tissue supports. I settled on two spruce link spars. A bit heavy but only 2.5mm square. The wings will also be supported by the wing struts so should be strong enough

There will be servo in each wing half to drive the ailerons. I am going to use Danny's method of sprung hinges made from floppy disk media and a pull chord to hold them down.

The wing was parked while I got on with the fuselage.

The UC fairing and spats have been bothering me since I drew the plan up. Apart from being draggy, I was puzzled how I could build these light enough for an indoor model but strong enough to withstand my landings

uc1.jpg

The LE of the fairing is from very light 3/16 balsa then seriously sanded down. The UC legs are bent through from 20swg piano wire and fastened to a 3mm lite ply plate - with most of the ply removed.. The root fairings are from 1.5mm balsa and sanded back

uc2.jpg

Another shot. I actually made an error bending the wire - the down leg near the wheel was about 8mm too long. I thought it looked odd. Fortunately I managed to straighten re-bend it without any damage.

uc3.jpg

The spats and wheels were from 3/8" balsa - the spats have 1/16" sides. I have cheated a little here, the spats are about 1/3 thinner than they should be. However at 4.6 gms, I am quite pleased

uc4.jpg

And fitted. The TE of the UC fairings are from 1/32" balsa sheet. You can also see the lower hatch. All access to battery, radio gear and servos will be here.

uc5.jpg

Finally, standing on its own wheels. The motor has been mounted )and then wrapped in cling film and tape to keep dust out and the front of the cowl added. Still some sanding to do but you can see how little wood there is left in the cowl sides. You can also see the flat edge of the spats, I have tried to maintain the shape on the outside but I am sure the judges will spot that. If AUW looks OK, I may well widen the inside as well before I cover it. Should be easy to do.

I still have the wing mounting to finish and the cockpit interior to do, but its coming along nicely. I need to get this mainly out of the way before I can start the fury.. Which I am itching to do...

More to come

Martyn

Thread: Announcing Plans for the 2019 Mass Build
10/10/2018 09:21:40

I have done every MB except for one (Skywriter). If the model choice is right then I'll be up for this one as well. My favourite by a long way was the Ballerina - scaled up by 115%. It is still my go-to model for days at the club.

The Astro Hog would be a good choice but its not a cheap build. It is a very big wing/model. I actually built one for the vintage Mass Build many years ago but it was 'lost' after a Rx switch failure crying

Thread: Laminated wing tips
09/10/2018 09:16:39

On my indoor or lightweight models I add a lamination of 0.006" unidirectional carbon, the next to inner lamination. I use cardboard templates edge wrapped with cling film as suggested above.

I tend to soak in luke warm water for about 30 minutes then draw the wood through my fingers to squeeze out excess water, I use PVA as an adhesive - lots of it but as its damp it just tend to run away (epoxy o the carbon layer). You need to pull the laminations very tight. I use pins in balsa blocks to hold the laminations in. When dry - usually within 12 hours in a shed environment, I then run a few drops of cyano into the seams before I remove the laminate assembly. This hardens the wood quite nicely

Thread: Hawker Fury Mk1 Replica, K1930 (OO-HFU)
04/10/2018 15:12:59

Looking good Andy

It looks smaller than I expected unless your mug holds half a gallon of coffee

Martyn

Thread: UKCAA @ Huddersfield MAC - 30th September (Revised)
03/10/2018 13:42:06

It looked great. Flew very well indeed

Thread: RAF's Finest Biplane? Hawker Fury MkI
03/10/2018 13:07:48

Hi Stuart

I have already sent you a PM with my address but I can see it hasn't been read. Click on the letter/inbox icon at the top of the page ModelFlying web page. It should be flashing at you

Martyn

Edited By Martyn K on 03/10/2018 13:08:24

03/10/2018 11:39:37

A quick question on the (full size) Fury Aileron linkages. I assume that the upper ailerons are connected to lower ailerons with pushrods and then a closed loop cable system. The lower ailerons were 'driven' by the pilot.

 

Is that correct? Still in the planning stage..

Edited By Martyn K on 03/10/2018 11:42:48

Thread: Hawker Fury Mk1 Replica, K1930 (OO-HFU)
03/10/2018 10:50:07

Looking forward to following this one as well Andy

Thread: UKCAA @ Huddersfield MAC - 30th September (Revised)
03/10/2018 10:32:32

More photos courtesy of Tony Saxby

saxby11.jpg

saxby12.jpg

saxby13.jpg

saxby14.jpg

saxby15.jpg

saxby16.jpg

saxby17.jpg

saxby18.jpg

saxby19.jpg

saxby20.jpg

03/10/2018 10:30:40

The weather wasn't brilliant but we still had a great turn out with a few new members as well. Very breezy and quite cold. The gusty wind caught out quite a few in the afternoon contest but there were no casualties.

The event was a morning fly-in and a 2 round contest in the afternoon to Pick5 and Pick7 rules. Great fun.

 
Flightline walkabout

 

Photos below are all courtesy of Tony Saxby

saxby1.jpg

 

saxby2.jpg

 

saxby3.jpg

saxby4.jpg

 

saxby5.jpg

 

saxby6.jpg

 

saxby7.jpg

 

saxby8.jpg

 

saxby9.jpg

saxby10.jpg

Edited By Martyn K on 03/10/2018 10:33:08

Thread: S1581 Hawker Nimrod MkI
03/10/2018 10:00:42

Hi Danny

Back to the fin rigging wires, this photo doesn't show a front fin rigging wire

hf 44.jpg

No hole either

Martyn

02/10/2018 16:33:17

On the full size and the model there is a slot in the fin for the rear fin >< tailplane rigging wire. I can see this on the plan. Your heading Nimrod shows a front wire as well. How will this be fastened Danny?

Martyn

Thread: Aldi bargains
02/10/2018 12:15:59

I got one earlier this year and paid £40 for it. Its useful, but not as useful as I thought. Quality is more than adequate for light usage,

Martyn

Thread: S1581 Hawker Nimrod MkI
01/10/2018 21:30:39

I still haven't unrolled my plan. Still too much on the building board and maintenance tasks this week. Will make a start in a few days. I just wish I could build as neat as that though.

What are the rudder hinges Danny?

Martyn

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