Building of the Vailly Aviation

92" Hawker Sea Fury

This is a story of a making a model of Hawker Sea Fury and participating with that model in the F4C competition class in the World Championships to be held in Sweden 2006.

	Oct. 2005 The beginning of this project happened when I bought the plans and cabin from Vailly Aviation a couple of years ago. It, however, was not started until October 2005 when I got the inspiration to finally start the building process. All the parts were sawed and sanded in a couple of days and the building started with the fuselage. I had to make a jig to hold the formers in place. This was constructed from heavyduty balsawood that I had no other need for. Because the inspiration was quite strong, the assembly process was started in the living room...
	December 2005 The fuselage formers were made from 3mm balsa with 0,4mm plywood on both sides. Light but quite strong. If I would do this again, I would use a good quality 3mm light plywood as it´s cheaper, strong enough and not too heavy. Also easier to sand and drill. The front fuselage sides are 3mm plywood with some lightening holes. I extended the sides to get the engine into correct location. They are also parallel to each other, original had some taper towards the rear.
	The tail wheel former is 3mm plywood. The front end has 3mm aircraft grade plywood parts and in some areas this is doubled for added strenght. All unnecessary weight has been removed from the formers, basically because it is not needed there!
	First pictures from the wing, the assembly process was quite fast up to this point. And we are now in my shop, it was time to clean the living room... The center ribs are from 3mm balsa with 0,4mm plywood on each side. Some landing gear ribs have 2,5mm and 3mm plywood reinforcements. The outer wing ribs are 2,5mm balsa.
	January 2006 The wing has 5mm x 15mm hardwood main spars and similar size balsa rear spar with shear webs starting from 3mm in the center and gradually thinning to 1,5mm in the tip. At the center the spars are divided to get clearance for the main landing gear. Wing sheeting was done with 2,5mm balsa. The sheeting alone takes 28 sheets of balsa! For this project I ordered 50 sheets of both 2,5mm and 3mm balsa and it turned out that almost all of the 2,5mm sheets were used at the end of the project.
	There are many lightening holes in the ribs, in retrospect I could have omitted a couple of these as they weakened the ribs unnecessarily in some areas. The balsa that I used was so good quality (light) that the holes made no difference in the total weight that was saved. I decided to make the elevator separable because I have to transport this beast to international contests. The connecting rod is a 16mm carbon tube with homemade glassfibre outer tubes. The outer tubes have 2 layers of 160g fabric on them. The outer curved end is made from 4 layers of 3mm balsa wetted, bended and laminated together.
	As the elevator was originally going to be glued to the fuselage, I had to make some plywood formers to house the tubes rigidly. The fuselage jig proved to be quite helpful at this stage as it was easy to make measurements of the correct elevator position and angle of attack.
	Some motivational pictures from this stage of the build, it starts to look like a big machine. The landing gear base has been glued to the wing. It is made from 4 layers of 3mm aircraft grade plywood as I didn´t have any thicker plywood at hand. Also the fuselage has been removed from the jig and the sheeting has been continued on the sides leaving only the bottom open to install some hardware inside. The fuselage is sheeted with 3mm balsa.
	The fin is now glued in place and some blocks glued to the front of the fin to get the correct curvature for the dorsal fin. Also a light plywood center rib is glued for the elevator. The engine heat is transferred trought these vents outside from the cowling. They are 30mm glassfibre tubes.
	The elevator servo is going to be placed in the root of the elevator with short pushrod. The servo is going to be Hitec digital 5245 MG. Picture from the wing attachment area from the fuselage. This box is made from 3mm plywood as are the sides. The wing is going to be fastened with 6mm steel bolts. You can see how close the parallel sides ended here with the outer skin. I´m happy with the result as it gives more space inside and it was easier to construct in the beginning.
	The full scale Sea Fury wing is not symmetric in plan view because the other side has a cooler for the engine. Both sides have carburator air intakes, Will see how this behaves in flight... Test attachment of the engine package, it´s quite compact with Toni Clark Hydromount and silencer together with Zenoah 62. I am thinking of rerouting the carburetor air intake to be inside the fuselage but I have to think about it a couple of more times.
	February 2006 Again motivational picture from the assembly, the size is beginning to be quite obvious. I got the landing gear from Sierra Precision, it is the scale version and is truly a masterpiece of NC-machining. At first I decided to make my own landing gear but soon realized that the time was running fast and it would probably be more expensive than this, although this aint cheap either!
	The landing gears are tilted forward quite profoundly which is a good this considering the landing approach. This way the impact is directed in to the spring and not so much in to the bending of the leg. The wing fillet is done from 0,8mm plywood with some formers to give shape for the skin.
	The wing fillet got its cover from 2,5mm balsa which had to be persuaded a little bit to correctly form into shape, it looks like a hedgehog now. The dorsal fin is now covered with easy to sand filler which needs to be sanded smooth.
	Wing bottom received it´s balsa covering of 2,5mm thick sheets. I used lot´s of pins and some tape to hold it together.
	Rudder servo is located behind the canopy in a honeycomb-balsa sandwich plate which is light and strong. Rudder control is with nylon coated steel wire of 45lb tensile strenght.
	March 2006 Tailwheel and it´s actuator are in very tight spot, I had to modify the control unit by replacing some alu parts with modified plywood bits. The actuator is pneumatic and the unit is from Sierra Precision.
	Fuselage to wing fillet is now sanded and looks very good. The front fillet was quite complicated in shape and this had to be done based on pictures as the drawing didn´t give any guidance.
	Tailwheel and mainwheel doors are made from a couple layers of 160g/m2 glass fabric. First I put a clear tape over the balsa to act as separator.
	The rudder wire is on a loop in rudder, this way no visible horns are needed. The wing bottom is now sheeted and wheel and servo wells are opened. I also made acces points for the drop tanks but sadly didn´t ahev any time to put a actuator inside the wing. So they are only for ground use.
	Flaps are made from 10mm carbon tubes acting as spar together with balsa sheet and plywood ribs. The tube is fastened from both ends with a roller bearing. Wing received it´s left side cooling duct. Sanding was quite a job. Hopefully it doesn´t give any unwanted phenomena in air.
	Landing gear unit is from Sierra Precision, it is really a masterpiece. It has the same kind of spring system as the fullscale. Wheels are Du-Bro 5".
	April 2006 Cockpit tub is done from balsa sheet to house the pilot and instruments. This way they can be removed if needed. The cowling side flap has been done from glass and filler is used to create the blended shape of the front fuselage to wing fillet.
	After all the sanding was done, it was time to do the glassing. I used 25 g/m2 fabric for this and SP115 resin. The most curved shapes were done in separate pieces and larger flat areas as one piece.
	May 2006 After the first very thin coat of resin I sanded the edges and added a second thin coat. Again some sanding and then the third coat but this time with some colouring agent added. This helps the sanding process as most of the third coat is sanded a way and only in some dry areas the third coat is left. With this method it is very easy to see when you have sanded enough through the third coat. It was a massive effort to wet sand all that, the wing is not a small area alone....
	June 2006 The tailplane fille was done by first clear taping and then laying and shaping a modeling clay in this area. Then a couple of layers of 160g/m2 fabric and filling it and sanding afterwards. It turned out to be quite nice looking.
	July 2006 And then, finally, it was time to do the painting. All the parts (and there were a lot´s of them) received a 1K primer first and then the final colour coats of Sikkens 2K paint. I run out of thinner and hardener many times, as there were a lot surface area to cover! Luckily I had access to a professional spray booth and this painting was a really a joy task to do. In retrospect I would have made the primer just a thin coat and not to fully cover the balsa texture. This only added unnecessary weight for the model.
	I did some panel lines to the wing and to the fuselage by adding some primer with a brush and using tape as edge before painting. It turned out to be quite a good looking after it was all painted. The final installation of landing gear and servos happend in my living room as the time was running out and I had to do 14 hour days with this project to get it finished before the competition. Luckily I had my sommer holidays at the time. All the small bits and things had to be finsihed before the first flight could take place. And there were a lot of them...
	Then I got the plane in a condition that I could begin with the engine testing. The engine, ZG62 with hydromount and Clark muffler, was brand new so it had to be run in before the first flight. I lost many evenings because engine did´t start and finally after installing the remote spark retardant system I got it running. Then the real shock came in one evening when I was making the final checks before the first flight. The plane was tail heavy, and I mean TAIL HEAVY! I had to put nearly 1,4 kg´s of ballast in the nose to get it balanced. And the total weight rose a very close to the 15 kg limit of the F4C class...
	The departure day for the competition quickly came and I still hadn´t made the first flight with this beast. The stress was awfull and I didn´t want to quit now (yes I did many times, but didn´t..;-)). I had to make the decision to drive to Turku where our boat harbor was and make the first flight there in local airfield. My home field has military activity during days so that was not an option. I did some additional engine tests (see the lead in top of the engine box!) and then cowled her up for the first flight.
12.7.2006 The first flight is done, YES! I was alone at the field so no inflight pictures to show from this event. I lined her up in the grass runway of Turku model airfield and then advanced the throtte. As she was still slightly tail heavy and had some up trim on elevator, the plane quickly arose from the grass and I had to put almost all available down trim on the radio to get her into level flight. The heavy weight was really easy to feel as a simple loop was a difficult to perform without a slight dive. I was flying full throttle all the time but still the speed was slowish.	The rolls seems to be quite nice, it has some tendecy to do a barrel roll instead of a axial roll. It must be because of the low wing position and some incidence on wing. Inverted flight is ok and I did some cubans as well but the most difficult problem is the lack of speed. This will show up in almost all figures which need some heigth changes like loops, cubans and immelmans. Then came the time for landing. I did some passes with reduced speed and it reduced the speed quite quickly and dropped height as well. I decided to make the first attempt without the flaps. The Turku airfield has no end obstacles so it is very easy to make a long shallow finale and this is what I did.	The landing was really nice and flat, no tendency to drop a wing or bounce. It took the whole lenght of the field to get it stopped and finally when it stopped at the end of the field I was really reliefed! It flies, with some challenges but it flies! Then I had to quickly load all the stuff back to my car and drove to the harbor to meet my team mate and board the ship to Sweden. The first flight had happened just 3 hours before our departure! Some might say that is quite tight...
	The next day we arrived in Sweden and drove to the competition site in Bråvalla. There we did the final detail and paintwork that we could to our models and assembled them in the gym area of local school building. While assembling the plane I discovered that my flap servos didn´t function at all! Obviously they had their motors somehow burnt, propably because they were pushing the flap against the wing when retracted. So I made a decision to tape the flaps shut and remove the servos for some weigth saving. The level of detail in some other competitors planes was astonishing, they really looked like miniatyres of the real planes. My Sea Fury, on the other hand, was missing landing gear doors, engine details, cockpit interior and the surface detailing...
	We had one official training day where all the pilots were allowed a one flight each. I did the flight and got some more confidence on the flight handling of this beast. The landing was bouncy as the hard tarmac didn´t absorb any impact. The competition started quickly on the next day and I was selected to be the first one from team Finland to fly. The flight was ok considering the circumstances and landing was, again, a bouncy one. Flaps could not be used.
	These pictures are taken by the local competition fotographer. The inflight posture of the Hawker Sea Fury looks really nice. You can see that at that time I didn´t have the landing gear doors installed nor did I have the actuator mechanism for the tail gear doors. The landing attitude is ok but after the first touch it had a tendency to bounce, sometimes taking a quite a big bounces...
	The end result from the competition was that I reached a 49th place. I got decent scores from the flight manouvres but in static the plane was lacking so much detail that it got severly downgraded for that. Anyway, the plane was in one piece and the goal was reached. In competition I did the 2nd, 3rd, 4th and 5th flight of this plane. Some other competitors have had their planes for many years so in that retrospect it was a success for me.
	Year 2007 What happened after that? Well the engine got swapped for a bigger twin, ZG80 for more nose weight and power. Some servos were moved forwards to help with the balance. And finally I got the gear doors installed and actuators working for both main and tail wheel doors. The cockpit is still to be done, but it will be done...
	In August 2007 I participated in F4C Nordic Championsips in Torslanda, Sweden. The result was 13th place. I also did some local competitions where I reached the first place.

Updated 15.02.2008