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Jul 27, 2013, 01:51 PM
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FMS T28 Part 9: Using a stock trainer towards the maiden

Not feeling much confident to maiden my heavy 3,7kg highly modified one, I bought a second hand stock 2,7kg V1 Trojan via internet. Although it had flown about 40 times from a grass field, that model was unscratched except for glued together broken main geardoor. The previous owner had kept it stock except for a reinforced nosegear and installation of a quality 60Amp ESC, and the addition of some weight in the tail. As we used the same batteries, and his Spectrum AR600 remained in the airframe, I couldn’t come any closer to a bind and fly model for a reasonable price, and according to his experiences, the CG was ok with the 4S4000 battery fully at the back of the tray. That Navy aircraft looked much more attractive as a stock one, due to detailed realistic weathering painstakingly applied by the previous owner.

Closer analysis back home revealed the flaps could be bent up slightly under high load factors, only being limited by the servo being stressed. I had encountered that phenomena in a previous FMS P51 and that had led to uncommanded roll inputs during loops or steep turns, and pullout of dives. On the mustang I corrected that with just two small almost invisible strips of carbon where the flaps met the fuselage, resulting in a kind of mechanical uplock point. On my training T28 I choose another solution, and just epoxied small scrap plates of hardwood resting against recesses cutout in the wing blend part of the fuselage. I later painted that white, together with the tailweights to conceal everything a bit, and that was acceptable because I never intended that model to become a show stopper.

I soon had it at the airfield for my maiden Trojan flight and was surprised how quickly it flew of the runway, and had to prevent the nose from raising any higher. Maybe the previous owner intentionally arranged it that way to relieve his nose gear from bumps on his unhardened surface, but this surprised me much and required positive control in a matter of seconds. Once at speed it behaved well and was easy to fly, but I preferred a more longitudinal stable model. The landing was easy after a long float (a stock T28 can be flown at ridiculous slow speeds) and I was able to keep the nose in the air long after touchdown. I then mechanically adjusted the elevators down so the angle after the flight remained the same, but now with neutral trim. Next I placed the recharged battery in the front of the tray. The second takeoff was much smoother and the stall check revealed no bad behaviors. Pitch sensitivity was now much better and a CG dive check confirmed it now was on the spot.

I used the model for what it was purchased, performing all kind of maneuvers to get a feel of the flight envelope, and adjusting my DX10t transmitter so the model responded to my likes. At the end I adopted following settings: no dual rate and servo links as from the box, 30% expo on the ailerons and the elevator, 40% on the rudder (mainly to minimize sensitivity of the nosewheel steering. I dialed in 15% aileron to rudder mix to neutralize adverse yaw and tendency for tip stalls during turns, but also use that feature for more precise steering (less abrupt) on the ground. Except for short turns I mostly steer the aircraft on the ground by ailerons, the mix causing the nose wheel the minimal adjustments needed to keep a straight line, also during takeoff and landing. The distance between nosewheel and maingear is so short it is easy to overcorrect with the rudder, the airplane weaving over the runway and causing much strain to the nosegear mechanism. I also found out a trimmed out flaps up aircraft needed only about 5% elevator correction for either takeoff or land flaps settings.

Compared to the other FMS 140cm span series warbirds, the T28 is remarkably easy to fly and even better, it is much more rigid and tracks as a rock, even in turbulent air. Aerobatics can be executed deceivingly easily and all controls are effective and harmonic, allowing you to fly precise scale like maneuvers. During most 8 minute flights, I practiced about 4 touch and go approaches, leaving the gear out for safety, before coming in for a full stop landing requiring about 30 meters rollout (on smooth tarmac) if landed at the correct speed with full flaps.

My first idea was to gradually add (non-functional) batteries to that training bird to increase the weight so I got used to flying it towards the 3,7kg my finished scale T28 weighs. Even if the bathtub with battery and wiring is huge, the canopy drops in rather low, leaving little space around the CG. I even toyed with the idea of flying with additional batteries without the cockpit in place, but finally rejected that, feeling this airplane could handle much higher weights without problems. I did replace the stock 500kv engine with the V3 580kv engine and that made a huge change. The airplane climbed out at twice the rate, and was now capable of flying immense round loopings, all with the stock scale prop. With just the removal of the prop, 3 screws holding the huge plastic nose cover, and the 4 screws of the engine mount, you can just then unscrew the 500kv and replace it with the 580kv, all in less than 10 minutes. I also was amazed the 580kv didn’t affect the endurance of the battery much, I still flew 8 minute flights with about 30% juice left after landing.

I slowly felt ready for nursing my highly finished T28 in the air, so I inserted my now proven 580kv engine in it, mounting the 500kv one back in the trainer. I also swapped the 60Amp ESc for a stock V1 50Amp in the trainer and put it for sale. It was gone in 2 days, without losing a penny. For the ones interested in seeing my former trainer in action, you can watch some footage still equipped with the stock 500kv engine on following links, taken during a windy day that kept all other club foamies on the ground. Unfortunately the camera was one of those modern ones with a screen, and the filmer had a hard time following my maneuvering Trojan in the sky, completely losing the plane on my baseturn to finals so the landing is not available.
The first shots are about the taxi out
T28navy taxiout (0 min 16 sec)

The second film covers the takeoff and first maneuvers till the cameraman lost me
FMS T28navy takeoff and maneuvers (0 min 57 sec)

The final film bit shows the rest of the maneuvers and the gear extension till he lost me in downwind
FMS T28navy man2 (1 min 38 sec)

A few weeks after those shots, I maidened my nice T28 after I had duplicated all the flight related transmitter settings from my trainer model into the scale one. I also put the old one on the Sig CG balancer and made sure my scale one balanced 85mm back from the intersection depicted in the manual. That maiden flight was in fact a non-event, the extra speed I took for the (no flap )takeoff and (takeoff flap) landing was too much, and the model felt very much at ease with its 35% increase in basic weight. It flew even more stable and had no vices during the intentional stalls. The only surprise I got was when it flicked on top of a loop. Recovery was prompt but that is what induced me in a higher speed landing as necessary. I didn’t change anything to the aircraft nor transmitter after that maiden, a proof the trainer aircraft had ironed out all the possible glitches.
A week later I had it with me again, and arriving at the airfield I noticed the real one parked in front of the hangar for maintenance. It didn’t take me long to photograph both together for some memorable shots of this matching pair.

The owner/pilot of the real one was amazed what I had produced, but even more when I fired up the engine with its associated Pratt&Whitney typical startup sound. He got his camera out and filmed everything but I’m still awaiting the DVD which he will hand me over next time we happen to meet. When he finally inspected my model in more detail he really was surprised to see himself in correct clothing in the front cockpit. He jokingly said he now was stuck always flying with the same cap. I pointed out I had installed a woman in the back seat, hoping I once could accompany him for a ride. He and his usual back seat friend immediately said that would be no problem in the near future, when it eventually fits our schedules. You can imagine what kind of smile that brought to my face.

After helping him put his aircraft back in the hangar because the maintenance guys probably had put too much pressure on his main struts, causing the tail to hit the roof even with the self-tow machine raised to max height on the nosewheel, I invited him to come over and watch my second flight. He also filmed that and was impressed how well it flew (when young he also was an avid R/C flyer). This time I had made a takeoff flap takeoff, and after aerobatic maneuvers (unloading the aircraft on top so it wouldn’t flick anymore), I made a textbook full flap landing, graciously turning off halfway the runway and shutting down with the typical sound a meter in front of his toes. I wonder how the film out of his pocket camera will turn out, and will post it when I get it. No further adjustments were needed but I’ll soon replace the stock nosewheel with a 2-1/4 inch one to reflect the large tire on his aircraft. I tried it on my trainer but it was slightly too wide for the cutout in the nosewell, causing it to stick out a bit and jamming the doors at the end of the sequenced retraction cycle.
Here are the 2 short sequences taken with a mobile phone by the owner/pilot of the real aircraft that day. Don't forget to open your speakers so you can hear the MrRcSound system during startup and taxi.
FMS T28 startup, real aircraft in background (0 min 30 sec)

FMS T28 flight2 takeoff (1 min 29 sec)

The first of September 2013 everything magically aligned. The weather was not so good, but it was flyable and a new member of our modelclub had a camera for pictures and movies. During the afternoon the owner of the real T28 landed from Germany in his light aircraft and when he opened the hangar we went looking inside. To my surprise he rolled the Trojan out, he had promised to make a few passes over the nearby airfield of Kiewit during their annual open door. Whilst preflighting his usual back seater came to me and told me I could take his place. Wearing jeans and sport shoes (due to the cold wind) I quickly boarded the plane via the built in steps in the port flap. Those were big steps and once in the roomy cockpit I got some help with the parachute and the 5-point safely belt. The guy then wanted to point out all the instruments but I declined, recognizing them at first glance since I had used pictures of his cockpit for my model. On the other hand, I insisted getting the operating instructions for the canopy and its emergency operation because I would hate surviving a mishap trapped in a burning aircraft, unable to get out because the pilot might be incapacitated. The glasshouse is enormous, operates by handles but also can be retracted by pneumatic pressure for quick exit.

Startup was uneventful but it took long to warm up the radial engine so I cut some parts of the movie out, and until now have no movies about the actual takeoff or landing, just the taxi out.
T28 start Laurence (1 min 36 sec)

The flight unfortunately got abbreviated by a birdstrike performing an authorised low pass over the Kiewit runway, at 200kts and about 30ft. We heard a load bang and although suspecting a birdstrike we couldn't see obvious damage. Only after we got out of the aircraft at Zwartberg did we notice how serious the impact must have been, this was no Colibri or other small bird.

I was very fortunate to get a ride in this full size aircraft, no matter how short it was, and all that thanks to building a model of it.

More to come on this page when things change or become available
Last edited by BAF23; Sep 11, 2013 at 11:33 AM.
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Apr 24, 2014, 11:22 PM
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Wonderful wonderful story. Thank you very much for sharing the build log and well everything. You are what makes this a good site!

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