Airsail - Dehavilland Chipmunk Kit

I haven't posted many updates lately, mainly because I'm taking a long time with the painting process and there seems little point in repeating picture at different stages of painting. Updates will follow soon as I hope it will be ready for flying next month!

 

In the meantime I'm stuck trying to identify one of the supplied plastic parts.

 

I can't find and mention of it in the instructions nor see any sign of it on the plan. If any past or present builders of this kit can identify it I'd be very grateful.

Hi Richard,

 

I'll have a look in my box of bits this afternoon and see if I can help. Initial thought - is it the duck tail that goes onto the very rear of the fuselage, extending underneath the rudder?

 

Cheers

 

Gav

Hi Richard,

 

I've not got too far lately. Been building a new "Hangar" and rearranging the garage as things wree getting unworkable. Have got as far as finishing the poly-C on the wing and have covered from behind the sheeted area with Solartex. I will take a photo and post it later tonight. Am looking forward to getting onto the fuselage and some progress. I think i have tried to re-engineer / over-engineer the wing to get it more scale like and caused myself no end of problems and probably not got the desired result. Anyway, it's all a learning curve.

 

Catch you soon

 

Gav

Richard,

That's the fairing that sits between the Horisontal Stabiliser and the Rudder.  It'll need some trimming.

Looks pretty accurate to the real thing actually.

 

Have a look here...

 

 

Cheers,

 

Hugh

 

Richard, I am hoping you can help me here. The 5mm sq stringers F19 and F20 - do they both run up and into the F1 Balsa? My F1 balsa has a 6mm sq notch in it and I'm unsure whether thet have just cut this a bit too big, or whether it should be 10mm to take both stringers.

 

I have found that he accuracy of the cut outs in the Fus formers is really poor, when I try to laminate the F2 balsa and ply the cut outs don't match.

 

My F1 ply former has no notches at all, but I think the plan shows stringers going through the F1 ply former. What was yours like?

 

Cheers

 

Gav

Gav,

 

No, F19 finishes just in front of F2  - shown with a bevel on the plan.

 

 

F1 Ply should not have any notches in it as it forms the front firewall face into the cowled area.

 

 

Hi Richard,

 

Sussed out F19 thanks, I picked it up as you say with a bevel on each end.

F1 ply okay then, I just can't be confident with anything in this Airsail kit!

The laminated pieces on the wiong centre section were like that in my kit as well, the tooling they have used for my parts is really poor.

 

Anyway, I guess that's the challenge.

 

Cheers

 

Gav

Hi Richard, more questions.......

 

When I fit the stringer F20 as far back as F6 it induces a twist in the fuselage in the direction shown. I guess if it is fitted with the rest of the fus all pinned down to the bench it might come out straight, but I'd rather not have a stressed structure. The position of the slot in F6 forces a sharp downward turn and twist in the stringer. My thinking is to soak the stringer and then fit.

 

I am really questioning if this looks right to you - I haven't put something in the wrong way???

 

 

Cheers

 

Gav

Gav,

 

I obviously can't look at mine as it is all sheeted in now.  But looking at the fuselage in that area the sheeting does have a curve to it so it follows that the stringers beneath must have the same shape.  I do have a vague recollection of applying a bit of steam to something and it might have been that so your idea of soaking is in line with that. It does look right.

Cheers Richard. I have soaked, set to shape and glued, will leave overnight pinned to bench and see how it comes out.

 

Rather than turn the plan over and wet with parrafin I have traced the profile onto some greaseproof paper, reversed this and used to assemble the other side. It is glued with the formers in place and left to dry overnight. (Forgot to drill the holes in the formers for the elevator control rod, so will have to work that out tomorrow night)

 

I am going to try and make a sliding canopy by embedding 2 brass strips either side of the fuselage, so will have to give that some thought before I start sheeting. The destructions state to complete the forward sheeting before joining the halves - can you see any reason why this can't be done last?

 

Where are you up to now? Have you sorted out a steerable tailwheel?

 

Cheers

 

Gav

Gav,

 

If you'll excuse me butting in, you might have seen, earlier in the thread, my musings on the tailwheel - whatever you do I wouldn't advise leaving it castering as per full size - but if you want it steerable rather than fixed as mine has ended up, how about building in an extra servo Y leaded to the rudder or on another channel, radio permitting?

 

Martin

I did the same with the plan as I didn't think the parrafin trick would work as I had covered my plan with clear plastic.  

I did drill the control rod holes but found later I had not got them quite right and had to redrill some of them later and had to make further adjustments after sheeting as they didn't emerge quite in the right places for elevator and rudder. Couldn't get any tool between the formers so turned a drill bit by hand - quite easy with balsa!

 

For the steerable tail wheel I have used one of these .  I made a ply base to fix the wheel support which I fixed above the bottom block as it the arm is such that the fuselage would be too high if you fit the arm after the block.  Had to improvise the control connection for it as there was no way to connect up with the rudder at the rear end. My solution was to put a splitter on the rudder control rod around the middle of the fuselage (I think between F7 & F8).  If you look back to earlier posts you should see a bit about the tail wheel.  With hindsight I would go for a separate servo for the tail wheel Y leaded onto the rudder channel. On the subject of servos the mounting is very much down to you to devise your own! 

 

As to where I am. I am getting towards finishing off.  At various stages of construction, everything has been fitted together, but now before final finishing I'm trying get everything together so that I can check the balance before I fininsh the tail as I think it is heading towards being rather nose heavy so may need to put some weight in the tail.  I've been a bit lax in photo taking in the later stages so have not got much to show!

   Great thread Richard.The chipmunk is one of my all time favourites,can,t wait to see the finished product!!

Emil,  Thank you for your kind words!

 

I've finally got round to taking some more photos.

 

 

Firstly, I would recommend to all future builders of this kit (or any other for that matter) to knock up a bespoke stand something like this.  I wish I'd thought of it earlier as it may have saved some of the damage I created in the process of building!

This shows the steerable tail wheel.  You can also see the elevator control linkage.  The paint on the evelators is not the final finish but I wanted to get the interfaces failed before I glued the hinges in place.

 

Here is a view of the tail. Work in progress glassing the fin with Poly-C.  Plastic trim also fitted to fin.

 

THe fuselage servo bay. Please excuse the current jumble of wires but I haven't sorted out where to fix the receiver battery yet.

 

Here is the engine mounted. I changed the standard exhaust manifold for a 90 degree version which nicely brought the exhaust round to fit neatly within the cowl. The silicon extension exits through a hole in the cowl.  I've also fitted a refuelling valve.

 

 

And with the cowl on, the refuelling valve is accessible.

 

Richard,

 

Please make sure that the elevator linkage doesn't introduce potential for flutter - the straighter the linkage the more rigid it will be - unless your bent linkage is very stiff it looks a little suspect in the picture to me.

 

I do appreciate that it may be far more rigid than it appears in the photo of course but it's better to be safe than sorry when you've done all that work so please forgive the unsolicited comment!