Danny's "poor mans Spitty"

[Danny Fenton]

Okay I think we have a result that will do. Its not perfect but without redrawing the plan it never will be. The fit of the rudder and elevator is lovely and tightly shrouded on the full size, and this is difficult with the way this is drawn.

However if you make the rudder leading edge something like this.....

completely rounded at the top hinge, but only partially at the lower.

The hinges need to be extended a couple of mm extra from the fin

The shrouds will need to be larger Hope they come off cleanly. Don't want to make another fin too

Cheers

Danny

Edited By Danny Fenton on 03/10/2014 16:42:32

[Terry Walters]

Looks like a workable solution Danny. I'll have go at the same thing. Like you say the full size​ is neat and close fitted. Not got anywhere near what I wanted to do today but have had good look at the elevators and a bit of thought needs to be given to cut outs for hinges in the core and providing for the elevator wire in the inner edges. There will be very critical line up of the hinge apertures for both elevators and the rudder.

Nobody said it would be easy! At least we have learnt that the plan cannot be relied upon 100 percent! Forewarned is forearmed!

Terry

[Danny Fenton]

Okay I think i will show how i did the tailplane, as long as I can get the warps out it worked reasonably well.

Firstly though somebody was sloshing runny CA everywhere so I thought I would show the sort of tips to glue that i use

Z ends I use for medium and thick CA without the small capillary tubing, with for thin CA

However these I find much easier to keep clear of blockages than Z ends. Simply tap the bottle on the table when you are done and the tube amazingly clears ready for next time.

These tubes allow the glue to flow almost like writing with the tip, the glues flows out in a very fine line, great for ribs etc.

You should not have to apply all but the slightest pressure, and usually gravity is sufficient.

Tailplane:

Same technique as Terry, but dont worry about them being absolutely perpendicular.

I glued the sheeting onto the trailing edge spar, and then trued the ribs as i glued them to the sheeting, curving the sheeting as I went.

[Danny Fenton]

I then trued up the rib lengths and shaped the leading edge before fitting

Sanding the other side of the leading edge in situ

I then added the 1/4 block for the fin post to attach too. The plan is vague here and I have followed Terry and made it full height. The easy way to make sure this block is absolutely upright is to make a short spacer from a stick of 1/8 x 1/8. measure from the rear spar to the rear of the block on the plan, then use this to position the block. A small chamfer will be needed where it meets the sheeting/skin.

As I might have said I have a wave in the leading edges, its the same on both sides, hopefully i can find a way to jig things before the top sheeting goes on.

Cheers

Danny

[Nev]

Looking good. This is my next step, is there any advantage in doing the sheeting in two halves, left and right, I'm only thinking it may lessen the stress in the sheet and reduce the warping effect.

Going back to the rudder, I'm not sure I understand what the problem was with number two ? I can see from the drawing of the 1/4 scale that the gap at the top between fin and rudder needs to be wider, so it swings true but isn't that just a case of ofsett tha hinge. I must be missing something.

Edited By Nev on 03/10/2014 18:52:33

[Danny Fenton]

Hi Nev if you can keep the sheet whole it will be much stronger.
The main problem with rudder two was it was too thin at the base. The hinge offset should be the same at top and the bottom. As it was only 8mm there wasnt room for the fattened lower section to lean forward as Jerrys does.
If you aren't too worried about the fit then just sand the leading edge to fit when central
Cheers
Danny

[Dennis Mulhair]

Hi Danny,

I've made a start and have created a build blog so everyone can follow my progress. Its called "Chipmunks for beginners" but I had a problem uploading my pictures even though I created an album called Dennis's chipmunk

Dennis

[Terry Walters]

Dennis/Danny - I've already sent Dennis a link to find out how to insert photos.

Terry

Edited By Terry Walters on 03/10/2014 20:50:38

[Martin Fane]

Hi Danny

Thanks for leading the way with your build log, I'm following slowly and learning all the time, fin is almost done. Regarding your tailplane, did you find the woodpack rear spar undersize compared to the plan like in Terrys build ? Did you use as was or cut a new one ?

Keep up the great work

Martin

[Danny Fenton]

Hi Martin, thanks for the kind words. The rear spar was a perfect fit. However I have orignal plans. I have had a copy made so that I could build over the copy and keep the good ones on the wall for reference. guess what the copies are a fraction out...... Are you using original Traplet plans?

I did do as terry did and that is slide the hinge hole over by the thickness of a rib

I am still in two minds about starting the tailplane again, I seem to be doing that a lot on this build but I reckon splitting the ribs is the way to go if anybody is watching. I think John is going to try that?.....

Cheers

Danny

[Martin Fane]

Danny

I have an original plan from traplet. I found the same as previous ie the plan view of the tailplane rear spar is larger than the actual woodpack part. However the view of the complete tailplane and the wood part agree.

I measured up the plan rib spacing and the distance from the tailplane centre line to the left and right rib 2s differ by a mm or so (this error was mentioned in another thread). This looks to account for the apparent error in the wood part hinge slot, maybe this is also why the ribs are slightly out of alignment at the leading edge when located as per the plan.

Thanks again for your great thread, its making this build a much easier task for a relative novice like myself. fin done, hope to crack on with the tailplane tomorrow, maybe even the rudder now you have resolved that little problem area.

Martin

[John Howitt 1]

Danny

I am enjoying your blog which is highlighting problems that I never foresaw. Your method for fixing shrouds was most illuminating. However would it not be possible to use a strip of ply of the same thickness as the sheeting and thus avoid the sanding down? I can't imagine that the extra weight would be much of an issue. What am I missing?

Keep up the good work.

John

[Danny Fenton]

Hi John the groove should be 1/64 deep the ply is the same thickness so very little sanding is needed. The shroud needs to be as thin as possible
Cheers
Danny

[Danny Fenton]

Well I hope you guys are enjoying my ineptitude here LOL I am now on my second tailplane, it took three rudders to get one I liked so I suppose its no surprise. The problem with the tailplane was the sheeting pulled the two centre ribs out of allignment dramatically, and I couldn't easily correct this. So I ripped it apart and have started again.

Now Terry has shown the upright method with great success, I still don't know how he got it to stay still while he glued it unless he has extra hands he did not confess too having when I saw him in July

Anyway, the other method and I would suggest it will be the easiest is to split everything in half and make the tailplane the same way the elevators and rudder are made with a central core. Dont forget to remove the 1/16 bit to allow for the core

So if you have seen those two ways and my rubbish build in the air way, what other way could we do this?

Well here is another method that works, a bit fiddly but here goes:

Basically using the plans you work out the amount you would have to pack up the leading edge, trailing edge etc to make it lie flat on the building board.

This may look a bit Heath Robinson, but the pieces of packing balsa are very carefully made the thickness they are. And they may look out of allignment but thats deliberate. I had to create a shelf for the leading edge of the ribs to sit on. Also be aware that the trailing edge must be packed up too, this is becuase the ribs are fatter between the trailing edge spar and leading edge.....and of course the trailing edge is tapered so needs more packing at the tips than the centre.

I just have to wait until the Titebond goes off to see if it is straight, fingers crossed......

Cheers

Danny

[Martin Fane]

Hi Danny

Sorry to hear about the tailplane woes, you must be gutted, lets hope the tail is the only area for these problems and the rest of the build is more straightforward.

I used your previous method for my tailplane construction yesterday - I left to come to work with just one skin to put on. I thought it was all OK and straight but now after reading your last post I'm worried ! maybe on closer inspection I will find the same problem - I need to get home and inspect !!

How did things go with your fin - I recall you wanted to fit a larger shrouds - did the old ones come off OK ?

Keep up the great work

Martin

Edited By Martin Fane on 06/10/2014 05:56:55

Edited By Martin Fane on 06/10/2014 05:57:09

[Terry Walters]

Morning Danny!

SWMBO says that if you are building 2 or 3 models then I needn't bother and can get on with the jobs she wants to be done!

Jigging up is the best way I think and most likely to succeed - I thought you said you were impatient? !

I used aliphatic glue to hold the rear edge and then clamped it. Next I teased the front edge down and glued/clamped it. Then turned it over and CA'd the ribs. Top skin was glued/clamped with aliphatic after the bottom sheet had set. It was the first time I had built in my hand and off board. Beginner's luck?

Hope to do bit again today but may get a wood delivery - we'll see!

[Danny Fenton]

Thanks Terry Couldn't wait to find out if I had a true tailplane.... I have Just need to block the hinge area and get the elevators made before I fit the sheeting to the other side

Cheers

Danny

[Tony Bennett]

been a bit of a trial then young man.

still it will all be worth it in the end...........................i hope.

i must order the plans for mine soon.

[Danny Fenton]

Thanks Tony, this is my first Dennis Bryant build and it takes a while to get a feel for how a desgner does stuff, and how accurate his plan is. I have been very spoilt by the Brian Taylor plans, they are very accurate and as long as your part matches the plan it will fit. This is a bit more hit and miss. I am glad I have started the way I have if I had started on the wings or fus undoing and redoing would be harder.

For those that are struggling with the BA hinges etc, here is the link to the screws washers and nuts required.

This is from MACC Models who I have used for quite a while, excellent service. Shipping will be around £2.50 so have a rummage at their other stuff. The 12BA nuts and bolts are great for detailing

PS I am not affiliated to MACC Models in any way, just a satisfied customer, I am sure there are other suppliers just as good.

Cheers

Danny

Edited By Danny Fenton on 06/10/2014 13:34:33

[Andy Muckley]

Hi Danny just started reading your'e blog and i must say what great work, i will start mine later and will do as you have done, it's brilliant with the pics to explain it all,as i think i would have been in a muddle without this. A big thank's mate.

[Danny Fenton]

LOL Andy just remember that we don't know what we are doing either We are just winging it! But we will get there

Cheers

Danny

[Terry Walters]

'Winging it' I'm a long way to being even at that level Danny!

Good news on your tailplane - the world was waiting! !

Thanks for the nuts and bolts link too - I've never knowingly bought BA sizes before - engineering is a world of which I know nothing! They'll be going to a UK address for me to pick up in a couple of weeks assuming you approve my annual leave.

Been building the rudder today and will post on my blog later. Interestingly, as I was looking at the fin and remembering your advice to make sure the bottom rib is at the right angle I noticed that in the cut pack that rib actually has that joint cut at exactly the angle req'd (as long as it's up the right way!) - it may be a fortuitous error - or - it my be the result a good bit of programming! Any one else got that? !

Terry

[Danny Fenton]

Hi Terry well the elvators are as much fun as the rudder. I think I have it sorted though.

Right in the wood pack, bet you were all wishing you had this now? Anyway the elevator ribs are included, however the rib in line with tailplane rib 1 (call it E1?) should be made from 1/4 blasa not the 1/8 precut. so transfer this to 1/4 balsa.

The other ribs in the set work outwards, the clue that you have the right ones are that they just fit within the core. The ribs have a correct way up as Terry aluded to (this was the same for the rudder) and only one angle is 90 degrees this is the one to go at the core leading edge junction obviously. The tricky part with this was getting the leading edge thickness right. Well I am pleased to say that as long as you bring the leading edge up to the same height as the pre cut ribs you should be okay

I seem to remember there was a question as to the taper of the ribs, curved or flat. All the pics I have looks to me as though the line is flat on the elevator and the rudder, straight from the leading edge radius to the trailing edge.

I haven't added the ttrailing edge stiffener/doubler yet but I will do. The reason for the edging will become clear when you cover the surfaces. The film will try to stick to the core and leave an awful wavy stuck down-not stuck down line. The edging balsa gives the covering a clear and definite edge.

Cheers

Danny

[Danny Fenton]

Oooo meant to show you a pic of the end 1/4 balsa rib and the profile for the leading edge. It looks like the profile/section on the plan but is thicker

Cheers

Danny

[cymaz]

Danny, with the hinge point inside the elevator, will it not bind while moving? Or have I missed something.