RP-Kestrel (Experimental) 9H-ADX

The first aircraft designed and built in Malta. It is currently located in the Main Exhibition Hanger at the Museum.

Background

One of our members, Reno Psaila, has kept himself busy these last twenty-five years designing and building a full size home-built aircraft, now registered as 9H-ADX. We’ll let him tell us all about it:

I was fourteen, and had just returned from Qrendi Strip on my bicycle. In a bag I had the remnants of a Hawker Tempest control-line model. I went into my father’s workshop and inspected the full damage. Next morning I decided that I would patch it up into a non-flying model and start designing a large-scale version. While enlarging the drawings on a sheet of 3-ply, which eventually finished up at the back of a wardrobe, a thought crept into my mind . . . maybe when I get older I will build myself a full size aircraft!

At 17 years of age I designed the first Maltese VW buggy which I named the RhinoBug and also worked on customising sports cars, which introduced me to working with fibreglass. Some years later I was designing hulls and superstructures for speedboats and cabin cruisers, which were produced locally.

Years passed, I got married and after I had my first child, I started building and flying radio-controlled models. The second model I built, I modified a mid wing design into a low wing version, which flew better than the original. In the meantime (1980’s) we started seeing R/C models with fibreglass fuselages and I built moulds of the most popular designs and started supplying other modellers.

End of 1983, I went to the USA to get my PPL. In one of the hangars I saw an unfinished VW powered KR-2 plans-built project and immediately the thought to build a full size aircraft surfaced again. Back in Malta, this became an obsession and I started researching on home-built/experimental aircraft. I joined the EAA, PFA and the French RSA and from the onset, I decided to first build a one third scale model to check the flying characteristics of my design. (This is known as the poor man’s wind tunnel.)

The model was ready in 1989, and Ing Joe Pule, who was the best radio-control pilot at the time, test flew it at Hal Far airfield. Kestrel flew well. Later Joe commented that: "…it was one of the mildest models I have flown. It practically landed itself. The model was so streamlined that I only used half throttle throughout the flight. I have no doubt that a full size one will have a similar flight envelope." I had used the same airfoil section on the model as the one planned on the full size.

At the end of 1989, I started laminating the fuselage in the moulds I had prepared months before. I had to seal and heat my one-car garage, situated at the back of my house, to obtain the right temperature and relative humidity. Three months later I extracted the fuselage monocoque shell from the moulds and Kestrel was born. At the time, the Malta DCA was not very encouraging as they had never handled a similar project before; so after consultation and guidance from Mr Paul Morley, I approached the UK Popular Flying Association (now LAA) to evaluate the design and build of Kestrel.

Although I worked on the project nearly every day after office hours, progress was slow. Every component had to be designed, plugs built and moulds taken, metal fittings hand-fabricated and aviation hardware sourced mostly from the USA. From the early stages I realized that to achieve my dream I had to break-up the building of the prototype into small components. Preparation of moulds was undertaken during the winter months and laminating epoxy ordered in time so that once the temperature in my workshop was above 18 degrees Celsius and the relative humidity below 65%, I would go ahead and laminate the parts.

In 1994 I had saved enough money to order my factory re-built zero-time Lycoming O-235L2C engine. Once this arrived I designed the engine mount and nose leg structure.

In February 2002 Mr Francis Donaldson, Chief engineer at PFA, was brought to Malta for 3 days to see the Kestrel first-hand and to discuss it in depth with me and PFA inspector Paul Morley. Trevor Crowe representing the DCA- Malta was also present.

The following years saw the Kestrel undergoing static structural limit load testing. The wing was loaded to 5.8g at 14 degrees positive angle of attack. The forward fuselage was subjected to a combined bending, torque and shear test under engine loads and side loads. The rear fuselage was tested under tailplane and fin loads, both symmetric and asymmetric; the tailplane and vertical fin were likewise tested. These static load tests were done at 1.5 x limit load.

Naturally all of the above work took considerable time as this required that first calculations were worked out and mode of loading identified and sent for PFA approval prior to the actual test. Rigs had to be built and after approval, conduct the actual test, prepare a report complete with photographic and video evidence and mailed to PFA HQ for final clearance. Suffice it to say that it took me nearly 3 months to pack over 8000 lbs of sand in bags containing 25 lbs, 15 lbs, 10 lbs and 5 lbs, which were each weighed twice on 2 different scales and marked accordingly. Incidentally all of 8090 lbs were loaded on the wing!

Luckily all the above tests proved successful. The one and only failure I experienced was while carrying out a load deflection test on the composite main undercarriage. One of the legs broke under prolonged loading and had to be redesigned and fabricated out of 2024-T6 aluminium instead. This necessitated a set of new-build leg fairings.

During 2006 to 2009 little progress was achieved although I did design and build a custom trailer in preparation for transporting the Kestrel out of my home-garage.

The period between 2010 up to the end of November 2013, was spent applying the final finish, acquiring the electric CS GT-Propeller, redesigning and fabricating the new instrument panel to accommodate a Dynon Skyview EFIS system, apart from the conventional analogue gauges and Garmin navcom, transponder and audio panel.

With the help of Mr Joseph Chetcuti, a very good and capable friend, we designed the electrical system and I installed all the cables and wired all the instruments. Joe then inspected the installation.

‘Ultraleather’ and carpeting material was ordered from Texas, USA for the cockpit furnishing. I had the stitching done at a local commercial outlet but I fitted and glued it all in place. The seats utilise ‘memory foam’.

Another 3 months were spent stitching a full aircraft cover; while I made out the patterns and material cutting, my wife did all the sewing.

November 23, 2013 was a big day for me. With the help of my sons Kirk and Dirk, now both grown men, and my ‘project-widowed’ wife acting as camera person, RP-Kestrel was carefully pushed out tail first from my workshop/garage with only 3mm space to spare from the tailplane tips and centre section ends to the metal door frame. Once on the road it was winched onto the purpose-built trailer and hooked to my Land Rover. We proceeded slowly to the Malta Aviation Museum at Ta’ Qali, where Ray and David Polidano were waiting for us. A second trip was made to collect the outer main wings.

Since then, I have been experiencing a strange ‘depressed’ feeling every time I enter my empty workshop/garage but it all goes away when I drive up to the Aviation Museum and work on Kestrel which now is a complete aircraft. Another ego boost comes from hearing the positive comments from the volunteers and visitors to the Museum.

I must take this opportunity to thank the Malta Aviation Museum Foundation, especially the Polidano team for making me welcome and for letting me use the space at Ta Qali to trial assemble RP-Kestrel and hopefully do the fuel-flow tests, system checks weight and balance and first engine run before disassembling the wings and transport my project to MIA for flight tests next year.

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