Justin's Raven

[justin.schoeman]

Some videos...

First attempt at a start:
http://www.youtube.com/watch?v=zxWNPe8bJ-g

Second attempt (a little more throttle and unnecessary extra mixture):
http://www.youtube.com/watch?v=53ajrg6seTA

Final run for the day (a little more juice and a deliberate lean-cut at the end):
http://www.youtube.com/watch?v=7wUWcb0Mdl0

[justin.schoeman]

I was very naughty, and took the weekend off to watch my nephew try out for
the Mozambique T20 cricket team (he was selected for the preliminary
squad!).

In the week nights, I have made slow and steady progress on the baffles. It
is horribly finicky work - the baffles need to seal perfectly, or you loose
cooling capability - which is probably the most important aspect of a VW
installation.

The baffles on the cylinders are high temperature composits, molded directly
on the cylinders - so they seal nicely already. Getting the aluminium bits
to seal as well is taking time.

Fortunately, tonight I figured out the trickiest bit - sealing around the
inlet manifold and the top of the head. It turns out a piece of 1" square
bar fits absolutely perfectly (after an hour with a drill and dremel).
Provides a good seal, and a rock solid anchor point for the rest of the head
baffles.

Will be another few nights of work, but will hopefully be ready for doing
the setup runs and tuning by Sunday.

[justin.schoeman]

Still slogging along. Regretting my decision to make my own baffles rather than use the Sonex templates and super-tins. In the end, mine will probably (they damn well better!) cool a lot better, but the amount of effort is horrible.

Here is a small sampling of the bits of baffle for one side of the engine:

The picture is missing the bottom edge baffles. The cylinder baffles are finished, but the cylinder head baffles are giving me grief. Should have made and fitted them before fitting the heads to the engine...

[justin.schoeman]

The final set of baffles (1 side shown):

Air does not leave the plenum without passing between 2 fins, or through controlled gaps around the exhaust ports (hottest part of the heads).

After all this work, I really hope this works as expected!

[justin.schoeman]

As usual, I didn't quite get as far as I wanted. Was planning on doing high power runs and tuning today - but got bogged down installing those %^&*( baffles. Which idiot decided to build them???

The results of the days labor:

Top View:

Bottom View:

Bad photo, but if you look carefully, you can see how much of the bottom of the head is baffled. Every mm^2 of fin area is exposed to flowing air from the baffles...

And a front view, with the plenum top on:

The sides do straighten up, once the screws are in...

[justin.schoeman]

Almost forgot - while I had some assistants today, I did the fuel flow tests. 65l/h level, and 55l/h with the tail on the ground. And the flow rate was maintained until a few ml from empty. Unusable fuel is also minimal. 450ml in level attitude, and 800ml with the tail on the ground.

This is another nice aspect of the AeroVee engine - the fuel system is incredibly simple. Finger strainer in the tank, tap, gascolater, carb. That is it. No filters, no pumps, nothing to go wrong. I hope.

[justin.schoeman]

OK - This has to be the most frustrating problem ever. Two weekends ago, I had the baffles and everything finished, and was ready to do some high power tests and tuning. BUT when I turned on the panel, my oil temp read 0...

I had redone all the fwf wiring, so this was the first suspect. All checked out OK. Next suspect - grounding. But that was also OK. So it had to be the sender, right? (I had bumped, and bent) the terminal while refitting the oil cooler.)

So I order a new one. A week and a half later I get a call - sorry not going to arrive before the holidays. So call MGL and Rainier says - no problem - just get a VDO sender from Diesel Electric. Grabbed one today, hooked it up, set up the sender, and hey-presto temp is 0...

Fitted new wiring, a dedicated ground line, and a little fiddling, and suddenly reading 23C! Start redoing wiring, hook it up again, and temp is 0. Fiddle some more, and it comes up, but a little later it is 0 again.

Lots of measuring and testing later, I discover the MGL is just not reading correctly. Turns out, the MGL doesn't display oil temperatures <21C! It goes 23, 22, 21, 0... The few weeks since the last engine runs were enough to briong ambient temps below 20, so that the MGL no longer registered oil temp.

Wasted a big chunk of time and money figuring this out .

[Duck Rogers]

I'm surprised that Rainier didn't tell you this, or is the instrument faulty?

[justin.schoeman]

I'm surprised that Rainier didn't tell you this, or is the instrument faulty?

I am sure he would have told me, if I had mentioned that I was replacing a faulty sender - I just asked him about getting a new one. Didn't tell him why.

The instrument isn't faulty - it is just the way they chose to implement the voltage-temperature conversion. The lowest calibration point is 20C - once you go below that they just give '0'... Obvious (I mean - who wants to measure oil temps below 20C???), but frustrating.

Fiddle with the sensor long enough (so that your body heat warms it up), and suddenly everything works. Leave it 10 seconds - and it just says 0...

[Aerosan]

Hi Justin

What sender did you buy?

Cheers Sanna

[justin.schoeman]

Hi Justin

What sender did you buy?

Cheers Sanna

At the moment I have a Nissan Sentra sender (using programmable probe setting), but the new one is a VDO 1/8" NPT sender. Can't remember the part number, but apparently all VDO oil temp senders use the same resistance range.

[justin.schoeman]

Made a good start at the cowling so far.

First, made a few fillers to block off the bigger chunks of dead space, then wrapped the whole thing in a lot of clingwrap. The lots of masking tape to close off the edges. Then some more cling wrap, and some more masking tape for good measure. If this leaks, I am going to be in deep doo-doo... Should really have removed most of the fwf stuff first to be safe - but I am too lazy .

Next, a few polystyrene sheets, marked, waxed and carefully positioned to give the reference surfaces.

Then I added some corex panels for the rest, and my cellphone battery went flat, so no more pics.

Unfortunately, I completely misjudged the amount of foam required, so I only managed to fill the mold about half way. I hope they are open on Tuesday, so that I can buy more.

With the mold framework held in place with a variety of clamps, straps and jacks, I can't really do much on the rest of the plane until this is done - so I suppose I get to take a little holiday now .

[justin.schoeman]

Plastocure was open this morning (fortunately) - so I got some more PU foam. Filled the mold after work, and peeled it:

Next, start cutting out the air inlets - these will eventually fix the shape of the nose of the cowl:

Tomorrow, lots more cutting and sanding...

[Boet]

Strongs mate, go do it somewhere remote. It becomes VERY messy, and it goes in EVERYWHERE when you start sanding! Wear goggles, for let me tell you, NOT nice when you get some blown into your eyes. Note my carving tool. Very handy for determining the initial shape. Just be carefull, that you do not end up with half a VW. Whatever: Let the creative juices flow!!







Now where the hell did he get to be so clever?

[justin.schoeman]

Strongs mate, go do it somewhere remote. It becomes VERY messy, and it goes in EVERYWHERE when you start sanding! Wear goggles, for let me tell you, NOT nice when you get some blown into your eyes. Note my carving tool. Very handy for determining the initial shape. Just be carefull, that you do not end up with half a VW. Whatever: Let the creative juices flow!!







Now where the hell did he get to be so clever?

Thanks Boet. Just finished re-reading your email before making the next assault on the workshop... Lots of good info in there!

Unfortunately, it takes two hands to maneuver the plane out of the garage, and all my friends have decided that this is a great time to go on holiday! So I will just have to keep working there, and clean the mess up later...