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K5682 - Martyn's Fury

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Martyn K04/12/2018 16:55:36
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A bit more progress.

The tailplane has now been slotted for the hinges and it seems fine. Quite happy with that

The past couple of days, I have been working on the fin and rudder.

The rudder hinges (on the full size) are a little bit more complex than the elevator. Its a sort of double take. At first glance it looks like they are hinged on the tube rudder post but that is not the case. the hinge is actually a small bolt hinge just in front of the rudder LE. a plate from the rudder post sandwiched between 2 plates from the TE of the fin.

So..

rudder1.jpg

I made 3 sets of these. 1.5mm GF and a short length of 6mm carbon tube to fit the slot that I will cut

rudder2.jpg

Sorry for the crap photos - they are quite small (8mm wide) and my new phone macro facility isn't as good as the old one.

rudder3.jpg

The pivot holes were drilled out for 2mm brass tube bush which was used to align the fin side of the hinges. In this photo you can also see a carbon fin post that will support the rear of the fin, dropping into a pseudo ali box at the rear of the fusealge

rudder4.jpg

The fin side of the hinge needs recessing further = about 2mm as the gap is too wide. The hinge line needs to be just on the LE of the rudder. There is also a small piece of GF board packing between the plates to get the correct separation for the rudder side of the hinge

The 3rd hinge set will be the lower pivot point that will sit in the fuselage.

More to come - albeit slowly

Martyn

Colin Leighfield04/12/2018 18:57:02
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Doesn’t seem slow to me Martyn!

Martyn K04/12/2018 22:30:17
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I am enjoying doing these fiddly bits. Probably a bit pointless as it will never be a class a scale model but these little touches will hopefully add a little je ne sais quoit. If that is spelt correctly 😂
Colin Leighfield04/12/2018 22:45:24
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Almost! (You don’t need the “t” unless you fancy a game on deck).  I’m currently suffering “stringer blindness”, but most of them are done now.

 

Edited By Colin Leighfield on 04/12/2018 22:46:23

Edited By Colin Leighfield on 04/12/2018 22:47:37

Martyn K05/12/2018 10:48:03
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4760 forum posts
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Wait til you start the cap strips Colin... You'll be needing a labrador

Colin Leighfield05/12/2018 15:15:52
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5551 forum posts
2266 photos

Oh dear, can’t I just use some thicker ribs instead?

Martyn K07/12/2018 12:12:41
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4760 forum posts
3436 photos

I have put the tail surfaces away. It all nearly fits but the hinge shrouds are a bit of a so and so to fit... Later

Made a start on the fuselage

Just like everyone else, I made two sides, one on top of the other.

fus1.jpg

All quite straightforward. The sides are separated by a layer of cling film

fus4.jpg

While that was drying, I started on the Firewall.

I am going to cut a big hole in the top to allow cooling air to flow through and probably out through the cockpit. As this is a big lump of motor, I have added another 3mm ply layer as reinforcement

fus2.jpg

Cut the additional slots out on the scroll saw. It really needs finer blades to get in all the fiddly bit.

When dry, I started to mark out the firewall for the inbuilt radial engine mount.

The prop shaft axis was carefully marked ( no side or down thank heavens) on the firewall and checked and double checked then left overnight and checked again..

fus3.jpg

I finally committed and drilled it.

So - although I dont have any pics the firewall and two front formers have been fitted.

However, I have run into a small problem.

How do you fit the very last former (that holds the skid)? The longerons are extended behind this point and taper together so the former cannot be slid over the longerons. I guess that you have to break the join with the last upright but before I butcher my carefully assembled fur can someone confirm that please?

Thanks

More to come

Martyn

Danny Fenton07/12/2018 12:23:32
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Hi Martyn, it ha sbeen discussed several times, even made it into RCM&E last time. The bulkhead has to be slid over with the blocks.

fury43.jpg

Cheers

Danny

Colin Leighfield07/12/2018 12:24:22
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5551 forum posts
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Martyn, it might make your eyes water to think about it, but I found that there was enough spring in the wood to pinch it in with fingers and slide through without it breaking. My heart was in my mouth but I got away with it. I had been thinking about cutting in three and gluing it in that way!

Martyn K07/12/2018 12:28:48
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4760 forum posts
3436 photos

Thanks both

Danny, I have tried that and failed However my longeron extensions look a little longer than yours, but I am sure that mine were cut to plan,

I'll try 'springing it Colin but I have used rather firm wood. They didn't seem too compliant when I tried easing it over

Martyn

Danny Fenton07/12/2018 14:32:44
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8840 forum posts
3699 photos

I puzzled over this for 5 minutes myself. It does go together without brute force.

The longerons do have to be cut to the plan length, and chamfer, otherwise it wont go on.

Cheers

Danny

Martyn K07/12/2018 17:30:24
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4760 forum posts
3436 photos

All sorted - thanks

Today is a decorating day. My task this weekend is to get the spare bedroom decorated ready for a new carpet and bed being delivered and fitted on Monday, The good news is that there is plenty of time while paint dries

Picking up from this morning

fus5.jpg

Front firewall fitted with cooling outlet. As my engine will be radial mounted, the main bearers are slightly smaller and the gaps filled with shims of beech.

fus6.jpg

All the side triangular bits fitted and into the jig for the pull together at the rear

fus7.jpg

I eventually got the former in place but I had to unglue both the rear uprights. At this point, the lower triangle is not glued in.

fus8.jpg

The reason why is that I had to cut a keyhole slot for skid.... which looks like this

skid1.jpg

Main skid from 1.5mm FG board, side panels from 1.5mm ply

skid2.jpg

The lower front rear edge is packed out with 2mm balsa. There is 1/32 ply bearing plate where the LE of the skid fits

skid3.jpg

And glued into place. A couple of short lengths of triangle to support the balsa

skid4.jpg

And another shot

skid5.jpg

From underneath.

The spring was something I had in my spring drawer and was stretched until the tension felt right. You can see I have also added a little extra reinforcement at the front of the ply former and the skid plates have triangles to hold them steady in front of the pivot

The plan is to add some 1/64 balsa sides and fair it very slightly

More to come

Martyn

Danny Fenton07/12/2018 18:13:32
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8840 forum posts
3699 photos
Your longerons still dont look chamfered Martyn? No wonder you had to take it apart. Getting the blocks in without the chamfers is not really possible, it's like a chinese puzzle
Looking good though well done
Cheers
Danny
Martyn K13/12/2018 10:39:50
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4760 forum posts
3436 photos

The bedroom decorating was completed but to be honest I felt too knackered to do much building over the weekend.

But I have made some progress though

fus9.jpg

I have move dthe position of the hardwood beam for the upper wing mounting. I have also increased the size as well. The M4 steel bolt captive nuts are moved nearer to the formers to reduce the bending load.

As this is raked, the bolt holes had to be raked as well so a drilling plan was devised

fus14.jpg

The cross hatch shows the thicker beams and the angle for the measured at 7 degrees. Note that the bottom beam has also been increased in size as well. 90mm M4 allen bolts are on order.

fus11.jpg

Stringers next... There are rather a lot. I used 3/32 on the upper deck but very light 1/8 balsa on the sides and bottom

fus12.jpg

A test fit of the tailplane was promising

fus17.jpg

A slight change from the plan at the front of the bottom stringers. They rest on top of a piece of 3/16 sheet balsa and then infilled the last 12mm with balsa. This is to try and get the wing fairings something like accurate - later

fus18.jpg

The side pieces were fun. The side pieces seem to fit better upside down..

A chat with our Mentor and Maestro put me right. I had missed or forgotten about the post with the correct shaped former sides.

fus19.jpg

The front upper hatch isn't going to be there. Access will be from the bottom. Two pieces of 1" triangle glued into place to give some wood to sand out the gun troughs. The rest will be planked with 3mm balsa

fus20.jpg

The sides went in place last night. These are 1.5mm balsa and will mainly have a second laminate of 1.5mm balsa on top. The reason. Well I am not happy with the cowl. It stops just after exhaust port 4. The full size definitely does not have a join there and I think it will look odd.

The ali panelling for the sides actually goes back to the cabanes so I am going to try extending by adding GF side cheeks to the existing Sarik Cowl (the shape following the full size panel lines). This will be 1.0 to 1.5mm thick and will sit on top of the balsa sheeting. The remainder will then be sheeted using balsa alongside the glass fibre extensions - if that makes sense. I now need to make a pair of gently curved female moulds - which I can do from the sheeted fuselage I have just done.

This is newish territory for me. It will be interesting to see how it comes out.

fus20.jpg

More to come...

Martyn

Danny Fenton13/12/2018 11:24:20
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8840 forum posts
3699 photos

Did you reshape the formers Martyn, or go with them as per plan?

When I lay a straight edge on the fus sides and the cowl, there is a significant dip around F1, very dissapointed in the plan in this area. So making an entirely new longer cowl would be the way forward. I don't think I have the stamina for that on this model. But we will see.....

Cheers

Danny

Martyn K13/12/2018 11:33:27
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4760 forum posts
3436 photos

I started with your revised shapes, but just slightly larger and then used a very long (1m) sanding stick to blend the formers in longitudinally. The side pieces went on very nicely as a result. I also added one extra former on the LHS as I thought the gap between the rear formers was a bit big

I am also not happy with the shape of the cowl. Full stop. It looks too dumpy. But I am going to have to make do. Making a new one from scratch is out of my comfort one. One day perhaps but not in the build lifetime of this model

Martyn

Martyn K13/12/2018 11:37:38
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4760 forum posts
3436 photos

Danny

I am rapidly coming to the conclusion that anything that was Class A scale in the 70s is probably only Stand Off Scale nowadays. There were just too many compromises that could be made which cannot be done today due to the amount of digital information available. I think that its something to bear in mind for the future.

As this is only intended to be SOS for me, I am not too worried but I can imagine the scale diehards (like you) tearing their hair out in frustration.

I have to admit, I am enjoying this build far more than the Chippie. Glad I did the wings first as well.

Martyn

Colin Leighfield13/12/2018 12:16:38
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5551 forum posts
2266 photos

I have used Danny’s new former shapes and so far they look ok. I followed the plan with the underside stringers and the block balsa sanded to a triangular section behind the lower wing root, that looks ok. As I started working on the wing seat I found that I had some apparent misalignment somewhere because the gaps between the bottom of the former side pieces were more than 1/8” above the seat, so had to extend them slightly individually to get them right. I hope to get on with that tonight. I have also been messing about with the side sheeting based on using 1/8”, 3 mm, but you say that you are using 1.5mm and double layering? That sounds like an easier way of doing it. I will follow your idea of running the sanding block alongside the side formers to get the profiles consistent. I find as I go along that I have to make adjustments here and there as I go along, some of it down to the plan and some of it down to my building accuracy or lack of it. I like the way you have done the tail skid, although I confess that I will simply depend on springy wire! There will be very little load on it in practice though so it should be ok.

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