My History (specifically to do with my KR2)

My Flying Experience

My flying career prior to fly the KR2 was
    213.8 hrs in 17 different types of Gliders/Motor Gliders
    8.7 hrs in the Light Wing (5.6 hrs to get my AUF licences and to go solo)
    5.2 hrs in a SkyFox Gazelle
    18 hrs in GA (General Aviation) aircraft more than 2 years ago.

I have an AEI (Air Experience Instructor) Rating and I'm also Aerobatic Rated in gliders. My powered flight experience is very limited. I consider myself to be a very inexperienced pilot, but I'm confident in my abilities and I know my limits.

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The KR2 as Purchased

When I purchased the KR2 in September 2003 it had supposedly been flown for 1 hour. The owner was selling as he was leaving Australia. I trailed the KR2 from Brisbane to home, Atherton Tablelands, some 1800km.

The KR2 was built to plans (so I'm told) and fitted with a Hirth F30U 2-stroke engine, 92HP at 6500 RPM. Propeller was home made 54" x 596". Instruments were minimal and basic.

Once at home I started checking over the KR2, first a weights and balances were done. My KR2 was in the very rear of the Centre of Gravity range. I decided to add a GRS ballistic chute to the aircraft as I had no grantees on the quality of the workmanship on airframe structural integrity. I spent the next 3 months going over everything I could on the KR2. I found the temperatures to be a bit high so I modified the cowling to improve the air flow.

In January 2004 I was ready to fly but there was no hanger space available in the Atherton area, so my KR2 sat at home in the shed till July 2004.

I had a test pilot to do the first flight, he lined the KR2 up and started his ground roll only to back off after 50 meters. He said there was something wrong as there was not enough power being developed.

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Engine Problems.

The engine had about 10 hours total running time, though it is quite old and has sat for some time while the aircraft was being built (prior to me purchasing it)

It started cold ok and appeared to run well, right up to temperature and for 15+ minutes, but was not developing enough horsepower.

I would shutdown and wait 4 minutes and restart and it ran very rough. I was at a bit of a loss since it ran fine from a cold start. I had to leave it 2 hours before it would start and run OK again. All 4 coils and 8 plugs are sparking, I checked them with a timing light to see if they would flash. I disconnected the taco to ensure it was not the problem. I replaced the spark plugs and checked every connection many times. I could operate the throttle and the engine rpm did not change. I tried leaning and richening the low mixture. I shut off the fuel to try and lean the engine out completely, all it did was cut out without the normal high revving of a 2-stroke before it stops.

Next I checked the fuel system. The F30U has 2 Mikuni carburettors that have a return line so excess fuel can return to the engine. I moved the return line so I could see any air bubbles returning form the carburettors. There were not any bubbles so there could not be a vapour lock.

Next I checked the electrical system as best I could, given that Hirth didn't supply any expected voltages for the electrical system or resistance values for the coils. Given that the engine performed correctly when cold, readings were taken. Once the engine began running rough the same readings were taken with very little difference in the results. Therefore the electrical was OK.

Next I pulled the engine and stripped it down to find rust on the front half of crankshaft. The bearings and the centre seal were very worn and totally unserviceable. The centre two con-rod small ends were also blued from over heating. The worn seal was allowing crank case pressure to leak between the front and rear chambers, thus causing the engine to run lean and cause over heating. From the over heating I could not trust the pistons, cylinders or heads. Therefore I was up for a new crankshaft, cylinders, pistons and heads (a new engine).

The problem was that the engine was not properly stored during the building period of the KR2. Moisture got in and rusted the crankshaft.

The original problem is NOT the fault of Hirth or the engine

While trying to diagnose the problem, I was frustrated by support not meeting my requirements or standards.

The local Australian dealer tried to help, but had never encountered this problem.

I asked the dealer for contact details of anyone who had the same engine as me so I could get some ideas from them. He said there was no one with a similar setup and that most F30's were in hovercraft or gyro copters. Still no one else to talk to.

I contacted the manufacturer and received no help and was referred back to the dealer. I contacted the dealer and the manufacturer and asked for information to be able to analyse the electrical system and did not receive any information. The dealer said that Hirth did not give him that information.

I eventually found other people with Hirth engines in a similar setup to me and non were happy with the engines.

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New Engine.

Having made the discission to replace the old engine I opted for a Jabiru 2200 engine, similar weight and 7hp less horsepower but a better torque curve and the best support I've ever experienced.

This required a firewall forward rebuild and a rework of the instrument panel.

The firewall forward rebuild was quite interesting and rewarding. A new engine mount, new cowling and new prop were required. See my Jabiru 2200 Engine page for more details. Were to put the engine (I know, up front) was the question, engine mount length cost me many sleepless nights. But, I resolved it, see my Weights and Balance page to see how.

The reworked instrument panel high lighted one particular problem, some of the gauges were to close to the compass, causing large variation. Also the fuel sight gauge was in the middle of the instrument panel requiring an empty tank to work on the instrument panel. I split the instrument panel into 2 sides.

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New Main Undercarriage.

While replacing the engine I decided to replace the retractable undercarriage with a more durable Jabiru undercarriage. This proved to be quite easy as Jabiru sell their components in kit form and all I had to do was create 3 mounting brackets to bolt on to the main spar using the old retractable's bolt holes.

Several mods were required to the peddle assembly to get the toe brakes working.

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Performance Information.

Now for some stats.
    Engine is a 2.2L Jabiru 4 cylinder - total engine time only 1.3 hours on the ground, engine red line should be 3300 RPM
    Prop is a Richard Sweetapple 56 X 56 timber prop
    Static RPM is 2800
    Initially max RPM was 2900, very tight motor.
    By 2.7 hours max RPM had increased to 3000.
    Best climb is 980ft/min at 80kts but the CHT's are climbing.
    Ideal climb is about 750ft/min at 100kts, Oil temp of 90C and CHT temp of 290F
    Stall is about 43kts
    Cruise at 115kts.

I'm very happy with the Jabiru. I'm only getting 115 knots cruise at the moment but that should go up as I make some improvements:

    1. I'm currently running a 56 X 56 prop which is limiting the Jabiru to a maximum of 2950 RPM, it should be a max of 3300.
       So I'm going to re-pitch the prop soon.
    2. I have no wheel pants on yet
    3. The holes for the old retractable undercarriage are still under the wings
    4. No Wing to Wing Stub joint cover strip yet.
    5. Ballistic chute protrudes below the engine cowl and will be fared at some point.

More information to follow as I get it together.