A wet Orange evening…

What do you do when your buddies throw you in pool at 11pm in the middle of the highveld winter?  Well, if you were in Vancouver, like my buddy Wim, you’d have your wife and family calling an ambulance to revive you perhaps… but in Johannesburg you can get thrown in the pool in midwinter and scarper out of it so fast so as not to properly damage your down jacket (well, we’ll see…)

But, you have consider the character of the mates who would do such a thing to you.  After watching the great Holland (congratulations Wim!) vs Uraguy game, and in the spirit of Ubuntu (see below) I imagined that we would all be in the same spirit of joy and unabashed fun. but….

 Mike Mason, who is the great impersonator of all things offbeat and wild, goaded me on.  And Topknott, that great big orangeheaded wingnut built of brawn and character, not only did not come to my aid at the moment of disaster, but actively aided and abbeted in the horrible moment… Spook, whom I have had eons of engaement with, described to me how he narrowly escaped my fate by jumping a narrow part of the pool… but didn’t help me out.. hmm…

And there are several others whom I have a bone to pick with…   At one’s time of dire need I imagined that you mates would come along to help you.. out of the pool, not into it.

In retrospect, perhaps I should not have thrown the hosts furniture into the pool though …

Night night all!

PS as an addednum, and an imporatnt one at that, I congratulate the Dutch team in thier win against Uraguy; it was an exciting last few minutes and, as the Uraguyans fought back, we all held our breath hoping that Holland would hold out… and they did.  Viva the Hollanders!

Archbishop Desmond Tutu offered a definition in a 1999 book:^[3]

A person with Ubuntu is open and available to others, affirming of others, does not feel threatened that others are able and good, for he or she has a proper self-assurance that comes from knowing that he or she belongs in a greater whole and is diminished when others are humiliated or diminished, when others are tortured or oppressed.

Racial Bias….

I was once asked, by an Afrikaaner, whether I was a ‘***fir boetie’, after I had defended a black storeman who worked with us. I replied, “no, but I’m not an Afrikaaner boetie either.” I have also been asked whether I am a racist. And I have wondered whether I am? I am the product of apartheid South Africa- a white SA male raised in the 70’s and 80’s. I was never really politically aware then (and now in many ways)- there were always too many interesting engineering type things to work out and explore.

But I had to go to do my military service and I had previously been exposed to a well controlled environment (by our then government). In the military we learnt all about ‘die swart gevaar’ (the black danger) and ‘die rooi gevaar’ (the red danger), which were the black masses and communism. In those days communism was a fairly real threat to all western governments, so perhaps that was vaguely real- but I think that it was simply an excuse to persecute government plans. The black masses were also a real threat, but that just because the National Party had kept them under the boot for so long, and because blacks were very badly treated in general.

As an aside, to demonstrate the kind of repression that existed, I recall one lecture that we received from an Afrikaans Colonel, telling us all about these dangers. At the end we were permitted questions- you could always tell when you had asked a question that hit a nerve or that the establishment or officer could not answer.  To ask a question you had to stand up to attention and then ask the question; if it was a question that could not, or would not be answered the response was, “kak vraag, sit!” (shit question, sit!).  In this particular case the consequences were a bit more dramatic and dire, if not as sudden.

A well educated political science student with more awareness and courage than I had asked  to present a question, upon which he stood up and very clearly stated that he thought that the ‘rooi gevaar’ and ‘swart gevaar’ were a figment of the SADF’s (South African Defence Force) imagination, followed by the start of a response to the points the Colonel had raised in support of his (the Colonels) argument. He didn’t get far and we were all sheparded out to get our ‘staaldaks, webbing and geweer’ (steel helmets, webbing and rifle) and to ‘tree-aan in die pad’ (form up in the road). This was normally the precursor to what was universally known as an ‘opfok’ (fuckup),which meant an hour or three of being ‘jaaged’ (chased) around an exercise spot somewhere in the camp, to teach us a lesson (and until you were properly opgefok- fucked up). Often the officers would arrange for an ambulance and medics to be present during an opfok, and then you knew that you were in for a serious opfok… This time they didn’t have time for that but we had a serious one nonetheless. So all this to say, the situation didn’t really encourage questioning… and if you weren’t politically aware you were fairly well inculcated into the system.

This is not to say that I was someone ‘who (in retrospect) always felt that what we were doing (in perpetuating the apartheid system) was somehow wrong’; I didn’t, but I also didn’t not- I was somewhat ambivalent. What I could relate to as being wrong was individual examples of mistreatment.

Back to the point… after the military service and out of the army one started to get more sense of life, and of course the free elections here (in SA) changed ones perspective. ‘People of colour’ were now your colleges; society was on its way to integration. What persisted was the bias that I had towards those people of colour, and what I struggled with was the issue of racism- was I or was I not, a racist? What really annoyed me was that, in this ‘new’ South Africa, it was cool to profess that we were all equal, and very, very uncool to be in any way discriminatory towards non-whites. My unease was defining for me- what I most desired was to be able to dislike whom I wanted to, for whatever reason; or like whomever I wanted to, for whatever reason. And I certainly didn’t want to be placed in any sort of category. But I did recognise that I had a racial bias; so my initial reaction towards non-whites was not favourable. Only when I got to know someone by some sort of interaction could I really form an opinion of how I would feel about them- and then it didn’t matter what colour they were; who they were had become more important. I think that bias is just part of the conditioning that I received whilst growing up in SA in the apartheid years; not an easy thing to unlearn. But I think that I can fairly say that I am not a racist… and that the education continues. Most of all, I would like to be able to like and dislike whom I choose to, without fear of being labelled anything other than ‘a standard person’.

Picture: the REAL swart gevaar!  🙂 

Gearbox back in; throttle stops stoppage!

Whoohoo! The new seals look as if they are working.  After the gearbox was installed we ran the engine for a while, and apart from a small overflow from the gearbox reservoir, there were no leaks.  We ran the engine for about 15 minutes and cycled the prop several times; for the first time the prop is cycling and controlling properly.  So now its back to fixing the myriad of snags to get the aircraft into the air.

One problem that has been annoying is that the throttle position sensor has been difficult to set up.  The throttle position sensor is a very important sensor that is used as a reference (together with the engine revs) to determine how much fuel to inject into the engine.  So calibrating it is important.  Unfortunately it seems to have been ‘clocked’ incorrectly, that is, put into the wrong position.  This means that it is biased to one side of its range and now one cannot set the throttle stops without some jiggery-pokery.  After mucking about with this for the last while and then trying to set it up properly again today I got fed up and decided to properly adjust the position or ‘clocking’.  In the first picture here you can see the side of the throttle body and the circled bit is where the position sensor is mounted; here the inlet pipe from the turbo has been removed (normally to the right of the throttle body in this pic).  The sensor needs to be rotated a bit clockwise to be able to use its range properly.

So I whipped off the throttle body and lurked off to visit Manfred Springer who has a small factory on the airfield.  Manfred is the founder of Aviate Aviation, the company that produced the rugged South African weight shift aircraft called the Raptor.  He is an excellent fellow and has been very helpful and generous in the past few weeks as I have been working at the airfield putting the Tundra together.  I set the throttle body up on his milling machine and, with some trepidation, drilled and tapped two new holes for the sensor.  It took some careful setting up and preparation- the drilling and tapping part is quick but it is always the setup that takes the time.  That done the body was mounted back onto the engine and all of a sardine I could get the proper range of the sensor.

From there it was almost a cinch to set the throttle stops- just a couple of lessons to learn about the interfacing software.  I ran the engine for 20 minutes as well and monitored the temperatures; all’s well so far.  The engine also responds to the throttle a lot better now that the range is properly set up.  The last photo here shows the sensor back in place (arrowed, bottom left), now properly clocked.  The throttle pushrod (double headed arrow) is pushing the butterfly valve open.  An interesting thing to note here is that this is ‘full throttle’ as I have set it.  It doesn’t look like full throttle, where the butterfly valve would be ‘flat’ relative to the incomming airflow; and in fact the valve can indeed open to that setting.  But, the travel of the valve, compared to the volume that is exposed as the valve opens, is very non-linear, so very small opening increments of the butterfly valve at the start of its travel makes a HUGE difference in the relative inflow.  After the valve has opened more than around 5-10 degrees from the closed postion the effect of futher opening is not as dramatic.  This is probably also due the the large diameter of the inlet.  So the ‘almost fully open’ position of the valve that you see here is actually way past FULL THROTTLE!  🙂

Possible next post- ZU-MUD’s first flight!

Re-assembling the gearbox…

Over the past couple of days I put the gearbox back together.  SKF, in the form of Andre Weyers, was extremely helpful in getting the new seals, O-rings and so forth.  He lent me his ear and provided some much needed expertise and advice.

The reassembly of the ‘box was fairly easy, but as with all things, its only easy once you have made all of the mistakes first; then you can get on and do it correctly…

First the main gear and its shaft was put into position and the housing lowered onto it, with replacement of the relative O-ring (the ‘gearshaft’ is arrowed).  This was all fine and now the ‘collar’ had to be replaced.  Here there are two pins that locate the collar into place, sized in the incomprehensible system of measurement (imperial) to ¼ inch, or 6.35mm.

One pin was missing (turns out later that it was in the hole but quite deeply- I saw it but assumed that what I saw was as blocking pin).  Getting a 6.35mm pin in South Africa is possible, but it takes time.  A mate of mine suggested using a drill and then cutting it to form a pin. 

The correct size drill is an equal pain to get but I found that a 6.40mm drill fitted very snugly and would work.  After I cut it and got everything ready I decided to have a quick poke with a screwdriver at the ‘blocking pin’ already in the hole.  Out popped the missing pin.  #$%&^^!!!

(right now I am listening to “If I ever leave this world alive” by ‘Flogging Molly’; as the composers might say, “ it’s a grand song!”  Thanks Susie!)

So now I was ready to put the collar into place; but here you have to be careful- you can put the collar in place and then slide the prop shaft onto its splines, in situ, but if you are not careful, and even if you are, you could push the lips of the seal out the wrong way- and then no more seal.  Also, you have to make sure that you align the hole in the gear shaft with the hole in the prop shaft so that the high pressure oil leading to the prop can get through. 

The propshaft is the blurry thing in front of the in focus chair (sorry, the light in the hanger is not good).  So you make a mark on the top of the splines so as to align them later.  Then you carefully push the collar onto the propshaft and make sure that the seal lips are the right way around.  Now you have the whole bangshoot ready to drop on to the box.

The gearshaft and propshaft oil transfer holes are lined up and the whole collar is wiggled into position. 

 The gearshaft is supported by two tapered bearings that are pulled against one another by a bloody great nut.  To tighten this you need two ‘special factory tools’, which were also required for the dismantling.  The first is a bloody great socket (which I think was an M36) which had to be machined down slightly to fit into the propshaft, and the second is a bar that has some lugs on it. 

This bar fits onto the propshaft so that you can loosen or tighten the nut.  The nut was tightened up and a bit of stout wire used to lock the castle nut in place.

After that the box went back onto the engine and tomorrow I’ll try to run it all again.

Lastly I lurked off to JR’s Exhausts where they kindly, and for free, added a bit to the exhaust so that I can put it back on for the test runs.  We are going to install a silencer and I had to cut part of the exhaust off to make a mock-up of the space in which the silencer can fit; so now it has to go back for the test runs and flights whilst the silencer guy makes the silencer.

It’s never over….

Jay

Crossflow Gearbox for Subaru Engine

The gearbox is used to bring the prop speed down to an acceptable limit – the engine crankshaft will turn between 4000rpm and 5500rpm to be in its optimal torque range, whereas the prop needs to turn at a max speed of around 2500rpm.  This speed is determined by the diameter of the prop- you want to aviod the tips of the prop going faster than the speed of sound, so the bigger the diameter the slower the prop must rev.

In the Crossflow gearbox two spur gears are used, with the larger gear having the teeth cut on the inside of the gear circle, and the smaller gear has its teeth on the outside in the more conventional manner.  The main shaft is supported by two big bearings and at the end of the shaft, near the propeller, there is a collar that is used to intoduce high pressure oil from the prop Constant Speed Unit (CSU) or governor, through a hole in the prop shaft into its centre.  From there it pushes up against the base of a piston in the propeller and this then changes the pitch of the prop, which is controlled by the CSU.

The CSU is mounted onto a pad or base on the gearbox, which is machined to a specific, fairly universal, pattern (AND20010) that is known to both the gearbox and CSU manufacturers.  The CSU takes engine oil at 3-5 Bar and pressurises it to 22Bar and then either delivers it to the prop or returns it to the engine, depending on what is required by its speed setting.

In the picture the oil is delivered from the engine at the top of the pad (the silver/ aluminium coloured bit) via the blue AN fitting.  It then exits out the pad into the CSU via hole A.  After being pressurised it goes back into the gearbox body through hole B and is channeled to the collar via drillings.  The collar is to the left.  At the bottom of the pad, opposite the oil inlet pipe and hole A is the return line from the CSU to the engine.  The flexible line that is to the left and below the pad (the one with the 90 deg bend) is what gave us our first problem.  This is an oil return line from the collar back to the engine sump.  Now that is just fine if you are not using a CSU as it circulates oil to the collar and back to the engine, or simply drains any oil from the collar back to the engine.

However, it does not allow any pressure to build up in the propshaft and so the piston does not travel and the prop will not cycle (change pitch).  After a while I figured that out and blocked the return line, like so:

Great, now the prop cycled and we ran the engine and started tests on it.  But after around 10 minutes of running oil started pissing out of the gearbox oil resevior.  The gearbox has its own oil bath, which has oil that is completely different to the engine oil.  Trouble was, the oil that was coming out of the gearbox resevoir looked to be engine oil…  With no support from Crossflow we decided to strip the gearbox down to try and figure out what was going on.  Here is the ‘naked’ engine in the front of the aircraft, now sans gearbox:

So now I opened the gearbox carefully, dreading perhaps hearing ‘sproing’ as some spring or equally vital part jumps out and dissapears into the same place that single socks go to; wherefrom they never return…

But it turned out to be fairly simple and the problem was immediately obvious.  Some oil seals had burst.  After going to SKF and getting a specialist to identify these it turns out that they are rated for a maximum of 5 Bar.  So 22 Bar popped them in short order.  Why the heck did Crossflow put 5Bar seals in an area that would see 22Bar?  Who knows?  I think that perhaps they were hitting a cash flow crunch (familiar to most in the aviation business) and shipped the box out, maybe hoping to sort it out later…

Here is the collar with the damaged seals.  The bottom left arrow shows where the oil comes into the collar from the CSU; it then turns and comes out the hole indicated by the right top arrow.  This hole aligns with a hole in the prop shaft and, even though the shaft is spinning around it is spinning in a pressurised chamber so the oil enters the centre of the shaft and pushes the piston.  You can see the damage to one seal between the two arrows.  These seals now have to be replaced with custom made high pressure seals that are being made in Austria for us.

Hopefully that will sort out the gearbox issue and we can get back to fine tuning the engine…

Posted by Jay Hyde

Subaru Aircraft Engine by Crossflow

I am having to learn this blog stuff so this is the second post of the same thing; not sure where the first post went!  This was meant to be linked to the photo in the previous post…

Crossflow was a Canadian company that used various Subaru engines as the basis for an aircraft engine.  They added bits like an Engine Control Unit (ECU), a fuel injection systems, inlet manifolds, wiring harnass and a gearbox that would bring the crank speed down to the required propeller speed.

They seem to have sold a few engines and then they went bust.  I have been working on one of these that was bought for use in a DreamAircraft Tundra, also from Canada.  When Crossflow went bust we were left in the dark and have had to puzzle out what they have done, mistakes and all.  Before I lurch off and slag Crossflow off let me say that I do not think that they set out to cheat anyone, or that they deliverately made mistakes to save  money.  The world of aviation, whilst seemingly awash with money, is a difficult place to actually make money.  This is mostly because the production runs are so small that it is very difficult to amortize your costs, and start up costs are huge.

So, whilst I am going to point out what problems I have found with the Crossflow product, I think that these came about because they were pinched by cash flow issues- in the case of this particular engine.  Whilst the engine has not yet been run extensively the basic engineering seems good and mostly the workmanship is also good.

OK, enough background.  The engine that I have been dealing with is a (I think) 2.2 litre one that has an IHI Turbo fitted to it- so not an ‘original’ Subaru supplied turbo.  It is fuel injected and has a DTA S60 ECU.  I have had great support from DTA in the UK (http://www.dtafast.co.uk/).  The first problem that was encountered was that the crank sensor (a hall sensor) was incorrectly wired in that its shield was earthed at both sides.  I didn’t pick this up but another Crossflow user did and I happened to see his post on the Aeroelectric forum (great forum by the way).  DTA recomends earthing on only one side and the engine won’t start if you have the shield earthed on both sides.

There were several other problems with the wiring as well, viz.; two of the high tension coils were not properly wired and not recieving power so the engine ran on only 2 out of the 4 cylinders at first.  The starter wire was not connected through.  The oil temperature sensor was not wired with a resistor as recomended by DTA.  No fuel pumps were supplied, nor any pressure regulator.

But worst of all so far, two of the oil seals in the gearbox were completely incorrectly specified.  They had a rating of 5 bar and there was 22 bar being delivered to them.  In my next post I’ll describe what happened and how we are busy trying to solve this problem…

Subaru Engine by Crossflow

Front of the Tundra

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