Chris Van Hoof's Cozy Mk IV

Plan # 219


Chapter 22 - Electrical Installation

Don't need wiring, till I have a plane ... That said, we will follow Marc Zeitlin and install the battery box in the nose ... since we obtained an IO 360 motor, but have a llok at the snazzy wingtips that I'm creating, they will house the strobe and the steady lights. Just does not make sense to have such a clean aeroplane and then hang stuff on the outside :-)

the preparation for the cutting shown here, lots of headscratching and trepidation.

Here you see the cut out piece on top, a shaped male mould for the lense and a block of wood that will become the mould for the right hand wingtip.

Just ordinary tools such as saws, files, rasps and sandpaper were used here.

These male mould then received multiple layers of duct tape to the same thickness as the perspex and polycarbon sheet that we will use.

This whole lot was put in a box and filled with pourfoam, thus producing a female side of the mould.

When the wife was out for the day we put the sheets in the oven and cranked this up to 140 deg C.

This renders the material soft and pliable and with gloves you just drape it over the male mould, push the lot into the female and wait for it to cool down.

The multiple varied curves taught me all about patience and perseverance!

So eventually we could use 2 out of 14 attempts, with 2 spare for in case.

Since we now have the lens, it is a matter of getting the shapes to match and then create a lip for the installation. The lens will be held in place with two screws.

And here it is fitted. 

And with this setup you will need some white lights to indicate the rear of the plane.

This was done by chamfering a 25 mm plastic pipe, which will received bright white LED's.

Q & A

 Does it look good - it does, to me :-)

How much time for this mod - all in exceeds 150 hrs.

Would i do it again - not really, change it maybe to a bolt on cover a la Jabiru.

(Which goes to show that any deviation from the standard plan sets you back more than you cater for.)

Because we gained such vast experience with the above, we felt that the "recognition" lights would be easier, and they were, mostly because the don't have compound curves.


Chapter 23 - Engine Installation

And  then my friend Brian Zeederberg  sourced an IO-360 and here it is in the workshop -- man, they have a lot of pieces.

We are learning all about aviation motors. At this stage I am not clever yet, but I'm learning fast ... what I have noticed is that they talk more bull about motors that about white wine :-) ... and everyone is an expert !

The engine mounting was being created by Wayne Estment's "B H Welding" outfit, since I used their facilities for smaller stuff, I can now recommend them ... and they don't charge US Dollars ... that means a saving of 50%, man they should start exporting to the USA :-)

Gavin Lawson put this all together as per the Lycoming literature and we will soon know how much power it puts out.

Both photos show the completed motor on a special transport stand designed by Gavin Lawson.

All you have to do is: hang the motor on a hoist, remove the stand, bolt the engine mounting on and install the complete caboodle in the plane.

Of course we still will fit the baffles, oil cooler, pipes, wireing and cables, but the end is in sight :-)



Due to the Rand / U$ exchange rate at the time, a ready made cowling was unaffordable, thus we make our own.

Anyway, we then fitted the motor to the firewall and determined the space required, as well as the clearances ... this is one very tightly cowled effort, so watch this space.

Gavin Lawson was talented with the lathe and manufactured a wood crankshaft, which was very usefull to determine the exact position of the flywheel, prop extension and to hold the former, as is shown on the photo.


Wrap it up with clingwrap (Saran wrap for the USA folks) and add foam and shape to suit.

Pollyfilla the plug, tape with boxtape so that it will release and cover with BID & UNI.

Here gavin Lawson (L) & Chris van Hoof are working against the clock, the winter sun was warmer than anticipated :-)

Wings removed, ready to turn the plane over, thus you invite your EAA buddies 

and have a lunch, after the turning :-)

We did tell you that the shell of the motor was installed, didn't we?

This photo made us decide to install the "boat tail" 

Gavin Lawson does the final shaping and measuring, before we do the layups.

And the final product, Top is on the LH, bottom on the RH.


So, once again we could get on with fitting the motor.

The plan of action is as follows.

Bracket to front and rear of throttle body to eliminate vibration. (rear bracket in position).

Carbon fiber pipe (here shown in blue foam) increasing in size (same as Lyc part but increase from 45 deg to 180 deg) to get air from throttle body to sump, etc. White foam indicates airfilter, just for show and tell.

and this is the foam core, ready for smoothing and covering with carbon fibre. the carbon fibre is not attached to the bracket - it will receive a carbon fibre flange - all manufactured in one piece. Of course, the alum bracket had to be made 3 times. Because my mother raised a slow child :-)

The inlet on the sump is off center, so we learnt to do this quicker :-)

Here is the freshly made carbon pipe still attached to the Aluminium flange. Foam was made smooth with Polly Filla, a plaster type filler, then sanded smooth (150) and sealed with red candle wax, also the holes, so that no epoxy could get to grips with this. Finally a good rubbing with Run-In-Wax which is a mould release agent. (Smells and feels just like ordinary floor wax). After the layups, it was left to cure 24 Hours at room temp (24C), then i shoved it in the house oven, at 100C for 3 hrs and 120C for another 3 hrs, then i got bored with it and declared it hard, so we'll have to see how it all pans out :-)

The sump drain is rerouted to the side (RH in direction of flight) for access. On the LH side of this photo we will manufacture an air-entry box which will house the airfilter.

And the final product, seen from the rear.

Then the exhaust pipes were fitted, I had the local exhaust shoppe bend a bunch of 90 deg angles, so that I could cut and tack this lot in place, about 5 hours total time.

Plane is standing upside down :-)


Chapter 24 - Covers & Fairings

We're nowhere there yet, so we don't even know how much we should worry.


Chapter 25 - Finishing

So we started on that filling & sanding thing everyone talks about, well I must be missing something, or maybe Graham Pick did such a superb job with the foam cores that it seems to be very little, bar the odd drip of epoxy ... anyway, it'll probably show once we start with the primer.

The gap on the strake to the wing is one metal blade hacksaw blade wide, so i chamfered the top edges, so that the silicone sealer will have some body to expand. The rear gap along the main spar is 3mm, same reasoning. Silicone sealer can expand up to 30% of the gap sealed, the one i've got does anyway :-)

This micro, filling, sanding stuff is not too difficult, it is really just a bunch of manual labour. The sun gets to you, here in Johannesburg, South Africa, so you work best before 10 am and after 4 pm. Otherwise you work in 30( to 40C ( 95F to 104F).

Anyway it took two weekends to complete the bottom of the LH wing and strake.

I'm getting fit, but not liking it, may just farm this work out ... we'll see.

And don't park your plane under a berry tree ... 

OK I took a decision to have the final sanding done by Arthur Smith. So that meant that we loaded the whole contraption onto a loaned flatbed trailer and pulled the wagon to Pietersburg (now called Polokwane).

The Landing brake must be pulling too tight against the body, so this will need adjusting, to stop the warping ... no, it is not the sun :-)

The advice from the group was to make a new one ... so there goes.

The Hinges seem to be proud by 1mm, and the specified screws sit out in the wind too, So i added two layers to the outside of  the hinge area, then recessed the taper end of the washer shown and floxed this in place. Then replaced the screws with SS taperheads and will finish the microfiller flush with the washer.

It looks faster, even if it isn't :-)



Internal Finish:

 I'll be finishing with a commercially available Hammer tone paint ... It looks a bit like the background to this web page, but with an ever so "subtle" blue/green finish. Its hard as nails, hides a huge amount of pockle and other unmentionables. But i do like the fibreglass weave that show thru, that looks really neat :-)

Universal undercoat is applied to get to the final gaps and spots ... everything shows up now!

It may not show clearly on this photo, but the nose was not round enough, so we ground all the paint away, added (max about 10 mm) micro and some bi cloth and did the finishing all afresh. Although it was round compared to a straightedge, it did not feel right when you ran your hand over it ... now it does :-)

The hand is an awful tool, it picks up the smallest imperfections, now you know why these amateur builders walk around an airshow feeling things :-)

External finish:

Samples of the colour have been done on my Partenavia wheel spats. Simply divine, so beautiful, I could just about lick them :-),

The paint used is Spies Hechter - MB511 white base, finished with a clearcote tinted with 20% Blue Green Perlescent.

Does it shine - you betcha!


Chapter 26 - Upholstery

We're nowhere there yet, but Gray with some Turquoise seems a good idea.


Test flights

Only imaginary flights have taken place, so far the performance is absolutely phenomenal.

Practical testing will be reported, when tests are conducted ...

Meanwhile, I'm now actually dreaming the flights ... its getting close !


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