How I made a STOL plane with a 250km/h cruise

How I made a STOL plane with a 250km/h cruise
I wanted to make an all-metal, fastest possible, two-seat aircraft with a wide, comfortable cabin and a true cruise speed of 250 kilometers per hour that could reliably take off from a small any other area within 150 meters at full takeoff weight (MTOW 600 kg) and land in an equally short area. In addition, I figured I would have an aircraft that would be quiet enough not to attract unwanted attention. The total purchase price had to be no more than 500 000 CZK.

Not one of the world's aircraft manufacturers meets that specification. Or not to my knowledge. And precisely because it is not easy, I resolved to do it, even though I am almost alone.

In short, I wanted to build a metal Shark with the features of a STOL airplane, like a Piper Cub, and the ultimate in on-board comfort like a  other full metal best plane, so I wouldn't feel like a sardine. I most like to modify things and equipment that have value and that have the potential to increase that value. It doesn't matter if it's an airframe, an automotive engine, or an in-flight adjustable propeller.

For my goal of getting a fast airplane that can take off from 150 meters, I purchased a warped (poorly fused) NG-6 600 kg kit airplane that was built the old-fashioned way. It was not made with a hole to hole system. One wing was warped, poorly riveted in the jig and the fuselage was cut in half before mating.


The two halves of the NG-6 Via fuselage before contact as they were brought home to us.


The NG-6 is a very similar aircraft to the another planes build in Kunovice, or at least an early version of it. The NG-6 dealer at the time was unable to deliver the rest of the parts even after several years, which he solemnly promised every time I called or even physically visited him many times. In the end, he didn't even answer his phone. Parts like the steering, cockpit, landing gear, inner bulkhead, other composite parts, rudder and the entire elevator were never delivered to me. I found out later that it wasn't just in my case. It wasn't the first time he did it, nor will it be the last. I tried to get the parts elsewhere from the primary manufacturers, of which there were many, but I always learned unpublishable things and that they were no longer making them, that they had to turn in the jigs and didn't get their due in time.

Cool, you got it! I thought...


I would have been left crying my eyes out if I had given up. I wanted it for the maximum possible amazing comfort on board, a spacious cabin suitable for long hours of travel, a very liftable wing allowing short takeoffs, a sexy shape and finally because it is the latest Czech all-metal construction.

I couldn't afford it, so I took a different route and built a very similar aircraft, called "DREAM TRAINER FZ", as it can't have the same name as the original, NG-4 and NG-6 Via, for the few changes described below.

The downside is that I have to go to an LAA approved technician every year for a technical inspection. However, I must thank him as he has been very busy with me and very understanding of my unconventional ideas. Above all for the grace with which he handled it. I'm very happy for him and thank him because he didn't hold back in helping me choose the most suitable solution from the many options I suggested.

I would also like to take this opportunity to thank another gentleman who helped me with the latest version of the elevator that no longer resists flutter, the metal rudder and also with other parts needed to complete the aircraft. We agreed that I would not name him. There are good people cheering on individual builders. I'm very glad there are, but it's hard to find them.

The DREAM TRAINER FZ is actually pretty much the same as the original NG-6 and Bristell except for a few modifications. You could say that I modified and further improved the original for my needs. As a user pilot of any short area and also as a test pilot, I felt further possibilities of improvement for my, one might say, specific use in operating on a short any other area near a 236 meter long forest.

I assumed that I would stop my 1.2 TSI engine conversion into the aircraft in the 2.0 version, engine codes CBZA, CBZB, CBZ, an all-aluminum Czech eight-valve, turbocharged, direct-injection, cylinder fuel-injected powerplant. The engine is re-chipped up to 140 HP and 210 Nm. I insisted on a very low noise requirement for the power unit and propeller so that complaints from nearby traffic would not come in unnecessarily.

I made the following modifications to my DREAM TRAINER FZ aircraft out of compulsion and sometimes for my own pleasure:

Modifying the fuselage for a different cabin and better stress distribution from the engine bed.

The original cabin has a frame underneath it, which is part of it and encloses the hull "ship" from the fire bulkhead to behind the cabin. Of course, I didn't have that with the cab and couldn't get one with the original cab for over a year. So I had to come up with another, equally massive, strong and aerodynamic solution.

I created a shallow D-section with curved ends from 0,5 stainless steel sheet, which when applied to the covering side sheet reinforces the whole cabin longitudinally around the axis of the aircraft and forms a safety arch - frame - behind the cabin. And it is connected as a welded unit to the individual fuselage bulkheads. In addition, I used a stronger Russian aerospace 0.7 mm sheet from old stock for the rear fuselage wall behind the cabin, which spreads the safety frame further into the fuselage tube without the rear windows behind the cabin. Should my plane ever tip over, the fuselage should be many times stiffer than the original. So it's a big plus for the crew.

From this longitudinal stainless steel frame, the internal engine bed is longitudinally extruded and riveted, forming an internal truss of 20×20×1.5 steel billets, which also distributes the forces to mount the 120-140 HP, 200-210 Nm 1.2 TSI engine. This truss of the inner bed - supporting the third point of the silent block, which is woven into the engine head - also houses the foot steering with pedals hanging down. Thus, the force distribution from the engine goes through the frame profile described above to behind the seats in the longitudinal axis of the aircraft, and at the front of the engine bulkhead the distribution goes down to the landing gear tunnel through two spars. I sized the truss for an engine with many times more power than I ended up using.

In-flight openable cabin

I like to feel free and I like to fly with an open cockpit, especially the girls like it during the golden hour before sunset, which is such an unreal romance...

That's why I adapted the cabin from a TECNAM P 2002 Sierra, which was available from an Italian manufacturer. This cabin is larger and more spacious in the crew head area.


Modifying the cabin for more interior space and easier cooling in the summer. Can be flown with open cabin! The cabin can fit two 2m guys and have more clearance in the shoulders and around the head.


The NG-6 is a very similar to another  aircraft  from Kunovice , or at least an early version of it. The then NG-6 dealer was unable to deliver the rest of the parts even after several years, which he solemnly promised every time I called him or even physically visited him many times. In the end, he didn't even answer his phone. Parts like the steering, cockpit, landing gear, inner bulkhead, other composite parts, rudder and the entire elevator were never delivered to me. I found out later that it wasn't just in my case. It wasn't the first time he did it, nor will it be the last. I tried to get the parts elsewhere from the primary manufacturers, of which there were many, but I always learned unpublishable things and that they were no longer making them, that they had to turn in the jigs and didn't get their due in time.

Cool, you got it! I thought...

I was counting on the fact that they make almost the same plane in Kunovice , where they had very similar components (cabin, elevator, rudder, end arcs), but the owner there, with whom I had otherwise good relations, told me that I should have chosen and bought a proper and quality plane from them. He insisted that he would not sell me a bolt for a competing machine. I really didn't expect that, although I understand it now.

I would have been left crying my eyes out if I had given up. I always wanted a best fullmetall type. I wanted it for the maximum possible amazing comfort on board, a spacious cabin suitable for long hours of travel, a very liftable wing allowing short takeoffs, a sexy shape and finally because it is the latest Czech all-metal construction.

I couldn't afford it, so I took a different route and built a very similar aircraft, called "DREAM TRAINER FZ", as it can't have the same name as the original, NG-4 and NG-6 Via, for the few changes described below.

The downside is that I have to go to an LAA approved technician every year for a technical inspection. However, I must thank him as he has been very busy with me and very understanding of my unconventional ideas. Above all for the grace with which he handled it. I'm very happy for him and thank him because he didn't hold back in helping me choose the most suitable solution from the many options I suggested.

I would also like to take this opportunity to thank another gentleman who helped me with the latest version of the elevator that no longer resists flutter, the metal rudder and also with other parts needed to complete the aircraft. We agreed that I would not name him. There are good people cheering on individual builders. I'm very glad there are, but it's hard to find them.

The DREAM TRAINER FZ is actually pretty much the same as the original NG-6 and very similar Bristell except for a few modifications. You could say that I modified and further improved the original for my needs. As a user pilot of any short area and also as a test pilot, I felt further possibilities of improvement for my, one might say, specific use in operating on a short any other area near a 236 meter long forest.

I assumed that I would stop my 1.2 TSI engine conversion into the aircraft in the 2.0 version, engine codes CBZA, CBZB, CBZ, an all-aluminum Czech eight-valve, turbocharged, direct-injection, cylinder fuel-injected powerplant. The engine is re-chipped up to 140 HP and 210 Nm. I insisted on a very low noise requirement for the power unit and propeller so that complaints from nearby traffic would not come in unnecessarily.

I made the following modifications to my DREAM TRAINER FZ aircraft out of compulsion and sometimes for my own pleasure:

Modifying the fuselage for a different cabin and better stress distribution from the engine bed.

The original cabin has a frame underneath that is part of it and encloses the fuselage "ship" from the firewall to behind the cabin. Of course, I didn't have that with the cab and couldn't get one with the original cab for over a year. So I had to come up with another, equally massive, strong and aerodynamic solution.

I created a shallow D-section with curved ends from 0,5 stainless steel sheet, which when applied to the covering side sheet reinforces the whole cabin longitudinally around the axis of the aircraft and forms a safety arch - frame - behind the cabin. And it is connected as a welded unit to the individual fuselage bulkheads. In addition, I used a stronger Russian aerospace 0.7 mm sheet from old stock for the rear fuselage wall behind the cabin, which spreads the safety frame further into the fuselage tube without the rear windows behind the cabin. Should my plane ever tip over, the fuselage should be many times stiffer than the original. So it's a big plus for the crew.

From this longitudinal stainless steel frame, the internal engine bed is longitudinally extruded and riveted, forming an internal truss of 20×20×1.5 steel billets, which also distributes the forces to mount the 120-140 HP, 200-210 Nm 1.2 TSI engine. This truss of the inner bed - supporting the third point of the silent block, which is woven into the engine head - also houses the foot steering with pedals hanging down. Thus, the force distribution from the engine goes through the frame profile described above to behind the seats in the longitudinal axis of the aircraft, and at the front of the engine bulkhead the distribution goes down to the landing gear tunnel through two spars. I sized the truss for an engine with many times more power than I ended up using.

In-flight openable cabin.

I like to feel free and I like to fly with an open cockpit, especially the girls like to do it during the golden hour before sunset, which is such an incredible romance...

That's why I adapted the cockpit from a TECNAM P 2002 Sierra, which was available from an Italian manufacturer. This cabin is larger and more spacious in the crew head area.


Modifying the cabin for more interior space and easier cooling in the summer. Can be flown with open cabin! The cabin can fit two 2m guys and have more clearance in the shoulders and around the head.



I had to cut, reinforce, extend and modify the cab and the front shield frame. I also had 7075 rails made to move the cab. The rails are inserted into the frame profile that was designed for them. This way I can fly with an open cockpit like a convertible. I close the cockpit during takeoff and landing because drift forms behind it and would impair takeoff and landing performance. Open cockpit cruising speed is limited to a maximum of 140 km/h. This open-cabin speed could be even higher, but that is assuming that I specially laminate the edges of the relocatable cabin, and I don't want to invest any more time in that.

More rudder authority and increased controllability in critical modes

From a lot of feedback from the flying public and from reading about aviation accidents, I've found that I'd probably need a much more effective rudder on this type of airplane that will work reliably even at those low speeds around 85 to 100 mph where I force the airplane to fly on my whatever other short area with rotors from nearby woods and farm buildings, especially when I fly year-round. So I raised the rudder, interspersed the main rudder spar, sculpted additional ribs and increased the surface area and provided corner relief.

I have not tested the rudder in a corkscrew, I am not qualified to do so, and sharp stalls and corkscrews are prohibited with UL aircraft, so I cannot tell you how the modification did or did not affect the corkscrew. However, at low speeds without prop blowdown I feel more rudder authority, also there is no need to pedal so much against reaction torque on takeoff, which is also related to the appropriately set engine axis about 4 degrees to the right and 2.5 down in the direction of flight from the pilot compared to the aircraft axis. Another advantage is greater maneuverability with the cabin open in flight.


DREAM TRAINER FZ with retractable cabin, enlarged rudder with corner relief, still without the composite wing fuselage transitions, end curves and aerodynamic wheel covers that I could not get.


Faster flap handling and greater flap deflection

The flaps were electrically operated on the original, which is a good "flap-proof" solution that incorporates increasing drag and lift at the same time during slow extension, thus slowing the aircraft down on its own, so you probably won't exceed the speed for flap stress. However, for my purposes of cross country flying and short takeoff and landing from a small area, electric flap control is a very unfortunate solution that will not allow the full potential of both the machine and any greater piloting skills to be exploited.

I have redesigned the flap control to a hand lever with a continuously variable adjustment with a latch and flap deflection up to about 45 degrees secured by a latch, and to another position of about 55 degrees I have the ability to extend the flaps by force. I simply hold the flaps in the position I need them. I have a direct response from the pressure on the flaps through the lever, and I can feel both the speed and force required to hold the flaps. The solution is some 45-55 degrees of flap extension without a latch and for competition use only.

Yes, of course. Such a solution is not for the "average pilot" and even a test pilot must think of a gradual, targeted and very deliberate reduction in forward speed while extending the flaps so as not to put excessive stress on the structure. However, this has its undeniable advantages. Using the flaps over 45 degrees and then closing them at the correct flare height of about 20 cm above the ground allows an immediate stall, which I usually accommodate by preceding with an even higher angle of attack, i.e. pulling the elevator. This way I can brake like a bird - still in the air. And after landing, I can use the full braking effect because the airplane is already without substantial lift.

Landings can be shortened by 50 to 70 feet using these gadgets if I play with high angle of attack at low altitude with flap control. The flaps can be manipulated and used in other ways.

End of I. part.

Filip Zejda

LETECKÁ ŠKOLA ROKU

V roce 2014 jsme se umístili na skvělém druhém místě v anketě "Letecká škola roku" ve kategorii škol věnujících se výcviku pilotů ultralehkých letadel.

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