Tuesday, 30 June 2009

June in review

It's been a pretty successful month and for the first time I feel that I can see the end of the project in sight. Not that the job is even half complete yet but I can sense that the number of unresolved problems is dwindling fast and I'm getting a better handle on how long things take.

The month started and ended with lots of purchasing activity. I've got most of the avionics that I need and am expecting delivery of the engine management system tomorrow. Apart from the paint job, I'm now more or less finished with the big price tag purchases, though no doubt there will be a few big bills associated with getting the Permit To Fly in the bag.

Meanwhile, I've made big progress with the fuselage, engine and wings, all of which are nearing completion. July should see lots of these loose ends completed. I'm looking into getting the aircraft painted, probably around September time and then I'll be moving from the local workshop up to Kirkbride airfield for final assembly and flight trials.

Exciting times ahead!

Monday, 29 June 2009

Closing the fuselage

Another minor milestone was passed yesterday when I riveted the starboard side of the fuselage, thereby effectively losing access to the mid section behind the cockpit except for via various small access panels. This was not done without a certain amount of trepidation! I checked and double checked that there were no missing or loose parts, antennas were properly fixed and no swarf, old rivet ends or other FOD were left inside.

In the end the 200 or so rivets only took about an hour to install. I then experimented with fitting the side windows, which, being curved, are somewhat awkward to precisely position. What a difference riveting and fitting the windows makes to the rigidity of the fuselage! And it looks good too.

I also did a little work on the engine, fitting various drain and venting pipes in place. Whilst these are no big deal, they are still important to the overall operation of the engine and have to be carefully routed to avoid sources of heat - the exhaust pipes in particular. I found the small metal stay that is used to support the airbox against the firewall and fitted that.

Finally, I spent some time auditing missing parts at the workshop in order to place an order today, hopefully. In the process, I found a few aluminium pieces that I can't for now fathom how to fit. No doubt I'll work it out in due course.

Today I hope to order the D120 engine management system. When that arrives I shall have plenty of work to do but for the time being I am more or less stopped on all fronts awaiting parts.

Total project time is now 150h 50 minutes. If you believe the marketing blurb, I am half way through the construction project. Somehow I don't think so.

Friday, 26 June 2009

What shall we call her?

Before too much longer I shall have to think of a name for SC700320.

Well, not so much a name - although that's not such a bad idea - rather, a call sign. All aircraft in the world have a unique call sign that is used to legally identify the aircraft and when talking to ATC.

In the UK, call signs start with a G, for Great Britain, followed by exactly four letters. For a small additional fee you can have any four letter call sign that has not previously been issued, with the proviso that naughty words are not allowed! Once a call sign has been issued it is never reused, even if the aircraft is subsequently scrapped or moved overseas and re-registered. That's a bit of a shame, because G-JOHN would have been quite nice. Long since gone, of course.

So my mind turns to suitable call signs. My Warrior is G-JLIN for, hopefully, obvious reasons. My initials are JRL, so I could have G-JRLS for example. Or perhaps G-JONS or G-JONL (ignoring for the moment the fact that my name is John, not Jon). My amateur radio call sign is G3WGV, so I could perhaps go for G-WGVS, though that looks and sounds a bit of a mouthful! And I'm not sure that I want to inextricably link my two main hobbies.

On balance, I think I'll probably go for G-JONL. It's not a decision that has to be made right now but time is marching on and the CAA is not known for speedy work, so I can't leave it for too much longer!

Wings again

Slowly but surely I am getting ready to finish the wings. Over the past few days, Chris and I have drilled out all the rivet pilot holes and carefully vacuumed out the resulting debris, using his rather excellent Henry vacuum cleaner. I've also finalised the pitot/static tube fittings, which required some thin tube for the pitot tube itself. It turns out that 3/16" windscreen washer piping from Halfords is the perfect solution, for the princely sum of £2.99!

I had just enough hardware in stock to fix one of the strobe/nav light assemblies onto a wingtip. The port wing turned out to be the lucky recipient. That done, we took a deep breath and riveted the wingtip onto the end of the wing. Chris was keen to have a few rivets to his name and the picture shows him working away on the top side of the wingtip.

Putting the wingtip back on for the first time in a couple of months reminded me just how large these wings are! The graceful upsweep of the wingtip certainly shortens the overall length of the wing somewhat but it's a very deep wing, which explains the excellent low speed handling, of course.

For now, we've not riveted the underside of the wingtip, so we still have access to the inside of the wing. This is necessary because I am still waiting for some nut plates for the inspection panels. Whilst I can mount them without access to the wing interior, I'm scared of inadvertently dropping one and being unable to retrieve it from deep within the innards of the wing! I think I'm going to have to give up on the factory and order them myself. I just can't wait any longer. Nut plates are not expensive but it's just very frustrating that the kit is incomplete and I seem to be unable to get any response from the manufacturer/distributor.

I also did a few electrical wiring tasks, far too mundane to detail here. Soon I shall have to make a start on the instrument panels but again I am waiting for parts. I shall be placing all sorts of orders for kit over the next few days, including the D120 Engine Management System (>£2000 just for that bit... ouch!). So very soon we should be able to completely finish the wings, the fuselage and the engine. Then it will be time to start on the interior, with instrument panel and upholstery the main work items to tackle.

Total project time is now 141h 35m.

Wednesday, 24 June 2009

Antennas and other things

Last weekend I took part in another fly in to Glenforsa on the Isle of Mull. Once again it was IFR flying both ways, which does make me wonder about how much use I might get out of the Sportcruiser, given that it is a day/VFR only craft. On the other hand, it's a gorgeous evening here and it would be absolutely perfect for a Sportcruiser bimble. Less than one quarter of my flying is in IMC, so perhaps I worry unduly?

Anyway, there's progress to report on various fronts over the last week. Firstly, I have been busy with the engine electrics, which are now more or less finished. Much of this is, for me at least, rather heavy electrical engineering, with lots of amps and correspondingly chunky cables. The starter wiring is all in 4AWG wire, which is a pig to deal with but at least the leads are short, so voltage drops will be insignificant, leading to better engine cranking speed.

I've also wired all the engine management systems, with the result that there are even more cables in the cockpit waiting for the instrument panels to be installed. Soon I shall have to start on the instrument panel, if for no other reason than to avoid being submerged under a sea of spaghetti!

With the assistance of my pal Chris I've also finished the installation of the Nav and Com antennas. All antennas were then checked for a good SWR (Standing Wave Ratio - a measure of the correct tuning of the antenna). The two Com antennas both show around 1.5:1 across the Com frequency range (118-136MHz) and the Nav antenna is similarly a good match in the Nav spectrum of 108-118MHz. That's good to know as it means that I can be confident that the entire antenna system is functional without actually installing the avionics. With that work complete we vacuumed out the fuselage and, as far as I can tell there is no reason now why the fuselage should remain open.

We've also been busy with the wings. I wanted to fit a stall warner and that needed the port wing to be laid flat on its upper surface, so I could position the sensor and run the cable. It's a somewhat scary proposition drilling the hole for the cable more or less on the wing leading edge! Not as scary as chopping bits out of the tail fin for the Nav antenna though. With that work completed, I believe the wings are similarly ready to be finally riveted closed. So it looks like I have a lot of riveting to do over the next few days.

Finally, we thought it would be a good idea to check out the horizontal tailplane. This has been hiding away in its wooden box since I first got the kit in March. Now with the trestles arranged for the wing work, it was easy to also take a good look at the tailplane. It looks good! Having got it out of its box, we couldn't resist the temptation to trial fit it to the fuselage. It's a bit of a tight fit, which is probably a good thing but it fitted easily enough at the second attempt and provided us with a glimpse of how the aircraft will look when completed.

I'm awaiting a package of parts from the UK distributor which will, hopefully, enable me to get on with completing the engine. Meanwhile it looks like I have riveting times ahead. Total project time is now 137h 35m.

Thursday, 18 June 2009

Wings 'n' things

I've not been able to spend a lot of time on the project recently due to some consultancy work and other interests. Nevertheless, there is some progress to report.

I spent a rather stormy afternoon placing a few hundred rivets in the wings. So far I've not actually sealed up the undersides, in fact there is still work to do on the port wing, installing the stall warner and sorting out the pitot and static pressure lines. Meanwhile, black clouds were gathering and soon all hell broke loose with lightning and thunder crashes and lots of pea-sized hail. For the next hour I was marooned in the workshop, a fascinated observer of Mother Nature's awesome power. Glad I wasn't flying!

I've also cut the holes to mount the wingtip strobes and navigation lights. Gauging the best position for these lights is not easy, as the wingtip sweeps back and up into a winglet. Unfortunately there is a fairly large area behind the aircraft where the wingtip shields the lights, so I shall have to give serious consideration to mounting a vertical fin strobe/nav light.

Back to the fuselage, I've mounted the Nav antenna on the vertical fin and heaved a sigh of relief that everything lines up nicely. I've also wired up most of the alternator electrics and a few more bits of control circuitry. So progress is being made, albeit perhaps not as quickly as I would like. Total project time is now 124 hours, 05 minutes.

Friday, 12 June 2009

Rivet, Rivet, Rivet!

Today I riveted the entire port side of the aircraft, some 220 rivets in total. This was the first real test of the pneumatic riveter and it seems to work very well indeed, albeit the spent mandrels occasionally do not drop out of the back, eventually necessitating some minor maintenance work. I would hate to even contemplate doing that much riveting with the hand riveter!

The other side of the fuselage stays open for the time being, as I still have work to do that is much easier while the fuselage is open. I think it'll be a couple of weeks yet before I'm ready to close the fuselage completely. Meanwhile, I feel that I've gained useful practical experience with using the riveter and I'm more confident about riveting up the wings now.

I also completed the heavy current electrical wiring in the engine compartment. This is basically the wiring to the master solenoid, the starter solenoid and, of course the starter itself. Rather than trust earthing via the chassis, I've run separate high power cable to the starter motor ground as well. I've used 25mm2 Tefzal coated wire, so there should be virtually no voltage drop when operating the starter.

Finally, and very carefully, I drilled and cut out the slots in the top of the tail fin for my Nav antenna. This was definitely a case of mark, check twice and then cut very carefully! The result looks good. I've fabricated a small frame for the antenna to sit on and that seems to do the trick. I just need to get some correctly sized mounting screws to finish the job. Then I'll need to cut corresponding slots in the fibreglass tail fin cap. I think I will wait until the antenna is mounted in its final position before attempting that!

I spent a total of 6 hours 30 minutes at the workshop today and it's good to see progress on several fronts as a result. Total project time is now 118h 35m.

Wednesday, 10 June 2009

Avionics & Fuselage

My avionics order arrived today. Lots of shiny new toys to play with! So I spent a happy few hours examining all the bits and trying to visualise how it will all look when it's installed. First though, I needed to get the antennas installed.

This turns out to not be quite as simple as I at first thought. The two communications antennas will be located along the centre line on top of the fuselage. The only problem is that this is where the two aluminium skins overlap and are riveted together. So one side of the ridge line is higher than the other. The solution is a small aluminium shim, so I fabricated one with a pair of tin snips.

I also had to drill out a few rivets and countersink them so that the antenna will sit flat on the surface. Finally I had to drill the mounting holes. This has to be done with quite considerable precision in order that the antennas are vertical and properly in line with the tail fin and each other.

That completed, I decided that I might as well continue with drilling out the pilot rivet holes in the fuselage. This is a bit tricky as it is necessary to line up the various internal bulkheads before drilling. Until they are riveted, bulkheads and, especially, frames are quite flimsy and it would be very easy to drill in the wrong place and make a mess of them.

So it's Cleco time folks! The trick is to drill out one set of pilot holes separately in the skin and then in the bulkhead. This ensures that the holes are in the right place and can then be Clecoed together. Nearby pilot holes will now be properly aligned and can be drilled out. The process continues until all the holes have been drilled or you run out of Clecos!

Well in fact I just had enough Clecos. I've now drilled out all the pilot holes to the correct size on both sides of the fuselage, ready for when I come to rivet the whole ensemble in a few weeks' time. It was also a useful learning exercise before starting the same task on the wings. These are an altogether bigger project than the fuselage!

Whilst I was at it, I drilled out the rivet holes for the tail fin fairing, as once the fuselage is riveted up, this fairing can also be attached.

Finally I looked into how best to mount the Nav antenna in the tail fin cap. There's not a lot of room up there but it will fit, just. I have to cut away a small section of the tail fin to let the antenna elements out. That's definitely a measure N-times, cut once activity! If I get it wrong then I'll have to replace the tail fin skin. Big job... and expensive. Let's not go there.

All in all some good progress on several fronts over the past couple of days. Total project time is now 112h 5m

Progress on several fronts

Now that the weather has become rather more seasonal I've recently spent some time at the workshop, with good progress to report.

Firstly, I've started on the engine electrics. There are various temperature and pressure sensors that all have to be wired back to the engine management system plus, of course all the power wiring around the battery and alternator. The instrument wiring was simple enough, albeit I had to think about how best to route the cables in order to avoid exhaust pipes and other stuff that little electrical cables are best kept clear of.

I have obtained a supply of heavy duty cable for the starter circuitry and am just awaiting the arrival of a suitably heavy duty crimping tool so I can attach the rather large terminals. Meanwhile, I laid the cables for the fuel pump and starter.

For various reasons, I have decided to separate the "Magneto" controls from the starter switch. This is mainly to make it possible to crank the engine without the magnetos active, as received wisdom suggests that this is the best way to start the engine when cold. A further consideration is that the pilot's (P1) instrument panel is quite full and there isn't really room for the very large combined magneto and starter key-switch.

So I've obtained a much smaller spring loaded key switch which will activate the starter and two small rocker switches will control the two magnetos. The rocker switches have red LEDs built in which I'll use as a warning light to show when the magneto is cut.

As I am stalled on the fuel system, awaiting parts from the factory, I'll be making more progress with the electrics over the next few days.

Monday, 8 June 2009

Avionics purchased!

Today I spent some money. A lot of money in fact. I finally placed the contract for the avionics for my Sportcruiser and should have lots of new shiny toys to play with in a few days time.

So what did I go for in the end?

Well my earlier article, where I was discussing my initial thoughts turned out to be pretty close to what I've ended up getting. Here's the list:
  • Garmin SL30 (Com 1 and Nav 1)
  • Garmin SL40 (Com 2)
  • Garmin GTX328 (Mode S transponder)
  • Altitude encoder for transponder
  • Intercom system
In addition to the above primary units, I've bought various support items
  • "Obs" indicator for SL30 Nav 1 (gives en-route VOR indications and also supports Instrument Landing System)
  • Antennas for Com 1, Com 2, Nav 1 and Mode S transponder
  • Mounting for my Garmin GPS296
With all that lot installed, my Sportcruiser will be very well equipped indeed. In fact it is almost equipped to full instrument flying standard and could certainly be used as such in an emergency.

Avionics is an expensive aspect of the expensive hobby of flying. The bill for all this kit was over £8000 and there's still a few minor items to source. But for such a nice aircraft there seems little point in scrimping on such things. After all, I shall, hopefully, be flying her for many years and will be able to get a great deal of satisfaction from having built her to my own exacting specification.

Friday, 5 June 2009

Winter returns

Golly! I went to the workshop this afternoon planning to do a bit more work on the aircraft. I lasted just over one hour! Just two days ago we had temperatures in the upper 20s. Today it's under 6°C, there's a sprinkling of snow on the high Pennines (I cannot recall ever seeing snow on the Pennines in June) and it's raining. After an hour I was frozen! It's colder than it was in early March when I was setting up the workshop.

So this is a non-progress report. I did manage to check out a few things and generally pottered for a while thinking about next steps and so on but no useful work was done.

This weekend I am supposed to be doing a 24 hour amateur radio contest from a tent in a field near Carlisle. Can't say I'm particularly enthusiastic. Pub sounds like an altogether better plan...


I'm rapidly coming to the conclusion that I need to change my strategy for instrumentation. My Sportcruiser came with what are disparagingly referred to as steam instruments. That is, each function has a separate physical instrument on the pilot's instrument panel. The modern alternative is misleadingly referred to as a glass cockpit and involves the use of large multifunction electronic displays to show essentially the same information.

Instrumentation divides into three categories
Flight instrumentation
I am essentially still a fan of separate instruments for the flight instruments. These are used to keep track of what the aircraft is doing and include four key instruments:
  • Air speed indicator
  • Attitude indicator
  • Altitude indicator
  • Direction indicator
In addition, it is usual to add at least two other instruments
  • Turn coordinator
  • Rate of climb/descent indicator.
Collectively, these six instruments make up what is known as the six pack. These instruments are in a standard layout in almost every aircraft and pilots get to know this layout very early on in their training. Whilst the glass panel implementation of these critically important instruments tries to approximately mirror the standard layout, this isn't entirely practicable, so there is a definite learning curve associated with the glass panel that does not exist if steam instruments are fitted.

A further problem with the glass panel for flight instruments is the sheer configurability of these modern systems. As a result, the pilot has multiple buttons to press, differing displays to comprehend and with all that the prospect of being suddenly unable to "read" the instrument at some mission critical instant. There is also the issue of placing all your instrumentation "eggs" in one basket - a problem that is sufficiently worrying that the authorities insist that some key instruments are replicated in "steam" form when glass flight instrumentation is installed.

I think I quite like the one instrument for one function approach, aka steam instruments, for flight instrumentation. These are instruments that the pilot refers to on a second-by-second basis and like the speedometer in a car, they need to be kept simple, easy to read and, above all, unambiguous.

So it looks like I'll be sticking with steam flight instruments then.

Engine management instrumentation
Things are far from so clear cut when it comes to engine instrumentation. In principle, there are dozens of engine parameters that can usefully be monitored and, in some cases, displayed. There usually isn't enough space on an aircraft instrument panel for so many dials and even if there is, it would be almost impossible for the pilot to keep track of so many different parameters.

This problem is solved in modern cars by using an engine management system which checks the myriad of engine parameters and, if something is amiss, lights an alarm indicator or, perhaps, provides more information via a multifunction display. This simplistic approach to providing information to the driver is not really adequate for aircraft engine management but the general principle adapts well to aviation.

Hence, I am seriously considering a glass implementation for engine management instrumentation. Typically, in a small aircraft such as the Sportcruiser, one might expect to display the following engine-related parameters
  • Engine speed (effectively, power)
  • Oil pressure
  • Oil temperature
  • Cylinder head temperature
  • Fuel pressure
  • Fuel level in each tank
  • Battery voltage and/or current
  • Engine running hours (Hobbs meter)
Already we have nine instruments and there are many additional things that it would be useful to at least occasionally look at. For example, although there is a cylinder head temperature gauge (CHT), that only monitors one cylinder. How much better to be able to monitor all four cylinders. Similarly, it would be nice to have fuel flow indications and, with that, estimated endurance, economy (in effect, miles per gallon) and so on.

Few of these engine parameters need to be monitored continually. Indeed, most of the engine instruments are only normally checked once every ten minutes or so as part of what pilots call their FREDA checks. But engine parameters can suddenly go out of specification without warning, so the ability for the instrumentation to continually monitor and, if necessary, raise an alarm is valuable.

For all these reasons, I am very seriously contemplating a glass engine management system (EMS). Unfortunately this means I shall have to get (and cut holes in) a new instrument panel, plus I will have a pile of unused steam engine instruments left over. I think the benefits far outweigh the additional cost. Ah well, what's another couple of grand given what's already been spent on this project!

Wednesday, 3 June 2009

Engine-ering (3)

I've been quite busy over the past couple of days, mainly working on the engine but also occasionally taking time out to tinker with other areas.

The engine is now starting to look a little more complete, with the exhaust and airbox systems more or less fully installed. The two systems are quite closely related because of the need to be able to select Carb heat, which in effect directs warm air from the exhaust muffler area into the carburettors. This is mainly to avoid (or dispose of) icing that can occur in the carburettor venturi, especially in humid conditions. In addition, the warm air from around the exhaust muffler is used to provide cabin heating.

So there are various large diameter hoses (scat hoses) linking the two systems and these too have now been installed.

I've also installed the throttle control lever and associated cables. The throttle control sits in the centre console between the two seats and actually has two levers, one for throttle and one for the choke control, used when cold starting. In fact there are four cables in total due to the fact that the engine has two carburettors. Two throttle cables and two choke cables.

Finally, I've at last done a bit of riveting! I was able to try out the pneumatic riveter and the good news is that it works very well indeed. Most times a single pull of the trigger completes the rivet pull. The result is a much cleaner riveting action than could ever be achieved using a hand riveter. This will be an enormous benefit when I come to install the 400 or so rivets in each wing. I just don't think I could contemplate that much riveting with a hand tool! For today I was content to set a grand total of 26 rivets to attach the mounting brackets for the tail fin fairing. A nice easy job to get started with.

Total project time is now 103h 5m

The LAA inspector's visit

Tom, my local LAA inspector came down to the workshop today to see how the project is getting on. There was quite a lot to show him and plenty to talk about!

Firstly he was able to check over my electrics, which he pronounced himself very impressed with. That's very reassuring as it's one of the key areas where there is little guidance in the manuals, so I've had to do most of the design and implementation work from scratch. He also took a good look inside the fuselage and checked out the undercarriage.

Next was the flying surfaces and we spent an enjoyable 30 minutes or so looking at the elevators and flaps (which are currently removed from the wings) and at the rudder assembly. All of these parts met with his approval, so we moved on to the wings themselves. An internal inspection is required so I had de-riveted the underside of both wings, ready for his inspection. Once again, he was pleased with the standard of construction and he has now given me authorisation to rivet up both wings and, thereby, complete one of the major build tasks.

Finally we turned to the firewall forward area. Here there is currently much work in progress as I am installing the engine and support services. Nevertheless, he was happy to inspect the engine mounting and firewall construction, all of which was declared satisfactory.

So a very successful day and a significant milestone in the construction programme. Tom signed off the following sections:

  • (1) Inspection of workshop facilities (actually this was done on his first visit)
  • (2) Fuselage structure and internal examination
  • (3) Wings internal examination
  • (5) Elevator structure and build quality
  • (6) Rudder structure and build quality
  • (9) Firewall and engine mounting
  • (10) Undercarriage
I also took the opportunity to discuss some of the ideas I am working on for instrumentation and avionics. It's also becoming apparent that I shall soon have to start thinking about things like painting and moving the aircraft up to Kirkbride. It's probably a few months away yet but if I can keep the current rate of progress going then it'll need attention fairly soon.

All in all a successful day. Chris and I went for a couple of pints and some lunch to celebrate!