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Dec 07, 2014, 04:18 PM
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Nieuport 17 Slowflier from E-flite

When I started flying indoor during the winter of 2013 I had no envy to buy the traditional aerobatic generic Depron models that are so popular. My penchant for scale led me to buy a micro Spitfire from Parkzone. Changing the delivered UK colored model into the Belgian markings MH434 like it flew during summer 1991, added much more weight and caused the minimum airspeed to increase so much that it became difficult to fly in our limited dimension sports hall, its small size also made it difficult for me to estimate its real distance from the walls. An internet search for a more suitable model made me search for a larger biplane. It thus became the E-flite Nieuport 17 which I ever dreamed of building as a full-size replica and for which I ordered the Redfern plans in 1983. I never realized that dream (due to the lack of suitable engine at a reasonable price) but decided to at least fly a model of it in my chosen finish of a Nieuport 23 flown by the famous pilot Edmond Thieffry during the first world war. Removal of the colors and decorations on the original model caused so much damage that I had to use too much filler on the tail, necessitating additional weight in the nose, and the additional paint coats and decorations didn’t help keep the weight down.
Nieuport 23-2
Being a rudder-only model, it didn’t turn well despite the much increased dihedral. Rolling out of even moderate turns required much anticipation, and I also experimented with different incident angles of the top wind in order to expose the rudder more to the airstream without being affected by the turbulence of the high body angle.
Video of the maiden flight:
Nieuport indoor maiden (0 min 28 sec)

I kept on trying it to behave during the following weekends, but to no avail, whatever I modified. It’s best use became to decorate my eating room by hanging under the light. Here are some movies of how it flew.
Nieuport - straighten up and fly right :-) (0 min 42 sec)

Nieuport part deux (0 min 26 sec)

For the winter of 2014 I purchased another Nieuport 17 E-flite kit, but with the intention of keeping it lighter by not modifying the original decoration. To get reacquainted of flying between walls, I initially got my old rudder-only Magnum out, and expectantly twice hit the walls AFTER being on the ground. A few days later I understood what happened. After summer flying months my fingers got conditioned to separate inputs for ailerons (in the air) and rudder (on the ground). On the rudder-only Magnum I connected the rudder to my usual aileron stick (I fly mode2 as in real aircraft). That worked fine in the air, but if things went wrong and I got it timely on the ground, my mind commanded my fingers to apply full rudder to avoid the wall, but that resulted in nothing because the rudder channel didn’t move anything on the model. That is the moment I decided to quit flying 2-axis airplanes and even for indoor flying equipping all my birds with proper separate aileron and rudder controls.

Modifying the Nieuport 17 kit for ailerons was a challenge because of the many possibilities. Bottom line, I first wanted it lightweight, then simple, scale like, adjustable, and with differential ailerons. The latter was driven by testing my aileron equipped Acro Magnum the weekend before. With my age, my reactions and depth perception are regressing, so I tend to fly slower between the walls. Those rather large ailerons lowering into the airstream produced a lot of adverse yaw and if unchecked by liberal use of pro-rudder, the increased angle of attack caused the model to rapidly tip stall. Thanks to rapid reactions it didn’t cause me to crash, but the recoveries were delicate saves in sometimes unwanted directions. The Nieuport having only two ailerons on the upper wing, rather small and getting ever wider towards the tip, would only aggravate the problem.

After a week of brainstorming and eliminating various options such as a servo in each wing directly actuating its own aileron by means of the servo arm being glued to the inner part of the aileron (discarded due to the weight of the double servos with long wires into the fuselage and aesthetically unacceptable looks on this 2mm thick foam wing), a single servo under the center of the top wing using pushrods and 90 bellcranks to move the ailerons by control horns (eliminated mainly because of weight concerns and difficulty gluing everything on that thin wing), I adopted a modification along the basic layout of the real aircraft, using torque tubes running along the top wings. Those were then connected to pushrods straight out of the cockpit. There was just sufficient space under the cockpit opening to cut away some plastic and glue small wooden blocks so I could mount a 5gram servo horizontally where the instrument panel would have been. The double servo arm then operated the vertical pushrods which were affixed to adjustable free rotating links.
A carbon or plastic torque tube would by itself have been lighter, but both ends would have needed glued-on arms to transmit the movement from the servo to the ailerons, creating excessive weight and the risks of things coming apart because of the very small glue contact area between slippery components. The very slow speed of the model and the delicate nature of the 5gram servo nylon gears made me opt for a single 0,8mm diameter piano wire judiciously bent at both extremities, just strong enough to transmit torque, but sufficiently flexible to absorb reverse aileron to servo forces in case of crashes. I used the same philosophy for minimizing the length (weight) of the wire and only connect it to the inboard portion of the aileron (even knowing the 1mm thick widening ailerons could wrap a lot). It’s kind of auto-correcting, at slow speed there is little wind force and the aileron will defect along all its width, at higher speed, only the inner portion will deflect much, the outer portion will remain much more streamlined.

Bending the 0,8mm piano wire was easy, 90 at the aileron side to be glued on the aileron, but at the center of the wing the bend was not made parallel, but at a 45 angle from the wing in order to create some degree of differential aileron movement. I still needed an adjustable connection to the servo, so I took some leftover x-shaped servo arms and cut 3 arms away. Those were slid over the length of the piano wire to be used as pivots under the wing. The remaining servo arm was the pivoted around the inboard section, and the end of the 45 wire bent to pass through the inner arm hole to transmit the torque without relying on glue. Once dry fitted for correct symmetrical angles on both wings, small slits were cut through the bottom of the top wing to accommodate the ends of the cutoff servo arms after a tad of PU glue was applied. After drying, the system seemed to move as intended, and the actuating servo arm got some adjustable pivoting guides bolted on.
nieuport 17-6
In the meantime the rest of the fuselage got assembled as per e-flite instructions, and final mating was approaching. Before making irreversible bonds, I mated the top wing to the cabane struts and cut the aileron-servo uplinks to what I estimated to be the correct length, then fastened them to the aileron system already installed in the wing, and used my servo tester to find out how things worked, and they didn’t. The straight servo arm pivoting movement was much too large and wrapped the wings, and although inserting the wires closer to the center reduced the movements, the connection of the smaller distance on the servo arm towards the wider separated pivot system negated all the benefits of my initial differential setup, and even resulted in reverse differential aileron operation.

With some mechanical analytical looks I found a workable solution. I replaced the straight servo arm by a x-shaped short one of which I cut off both upper arms, resulting in a negative v-shaped contraption that could restore the differential movement up. Unfortunately, my cut off vertical pushrods now became too short and I had to make slightly longer ones (easy task with z-bend pliers). That system operated like I wanted, but simulating air load on the aileron revealed that the 0,8mm wire was not sufficiently torque resistant to transmit the movement. There was no way I could remove the already installed assembly without damaging the wing, so I opted to use rigid plastic sleeve material which was solidly glued around the thin piano wire to increase the torque resistance. I thus had to cut lengths of tube to fit between the wing pivots, cut the sleeve through over its length, applied glue to the wire, pushed the sleeve over the wire span wise, then rotating it to spread the expanding glue, and all that without a single drop of glue or damage on the 1mm thick Depron it was almost touching. Strips of thin paper that I moved every 10 minutes during the first hour ensured everything moved freely, and after another dry-fitting and aileron operation test I was satisfied the system could operate satisfactorily.
The rest of the assembly of the model was performed as per instruction booklet, except that I mounted both the ESC and the receiver forward of the firewall. That gave me more freedom to play with the battery location in its large cavity. The flimsy plastic wheels being too slippery for polished indoor floors, I replaced them with stronger wheels hubs with rubber tires, to which I glued the inside and outside conical dishes of the cutout kit wheels. Incidentally the original and improved landing gear assembly both weigh exactly the same 21 grams.
Even using ailerons, I kept the recommended kit dihedral but used 0,3mm nylon fish wire for the bracing wires. They are less visible than the provided kit wire, but at least passing them through the many holes and especially fuselage tubes was much easier. The aileron system in the center of the wing allowed for only minimal clearance for the flying wires, and a tweezers had to be used to pass them through the aft cabane struts. With all the slack taken out, PU wood glue was applied with a toothpick in the strut orifices, and the next morning everything was solid and the dihedral remained in position after removing the artificial wing supports. A lightweight pilot figure was glued in the cockpit, and after a weight (250gr battery included) and balance check (no lead used), the battery was kept in position by elastics and the control throws verified and adjusted. The 87cm span model has 19,03 square decimeter wings and the wing load calculates at a mere 13gr/dm2. The Old cannibalized Nieuport 23 next to the newly rigged Nieuport 17
As I learned from another experienced “scale” indoor flyer, mixing a serious amount of rudder with the ailerons, made the model much more responsive, and reduced the tendency to tip-stall during sudden turns. I wasn’t ashamed to dial in a 50% mix, and kept it that way after the proving flights. In our small sports hall I used the diagonal to first make a takeoff, a few wiggles of the ailerons, and landed straight ahead before the corner. Being pleased with both the banking and leveling capabilities of the model, and reassured that the balance looked good and elevator control was adequate, I taxied back and took off again. This time along the flight line so as to allow a 200 degree turn before the wall, landing the opposite diagonal (there luckily is no up- nor downwind in a sports hall). The banking and rollout during that turn were 5 times easier than with my first Nieuport, so I lined up again and this time took off for a real flight. This time the full patterns proved easy to control, and even tighter turns were possible when experimenting with various circles in the middle of the limited room. A few landings were executed, but it became clear this fighter had to be landed with about half power, otherwise it drops its nose too fast.

Very satisfied about the first real flight, I quickly made some control adjustments and talked to the others (who stayed on the ground during that maiden). Besides that it flew well, I got very little usable inputs. Some thought I needed a coarser prop on the Turnigy 2211-2300 because they heard my engine scream without producing much forward speed. I had flown mostly around power, and felt comfortable with what I saw and felt. Hey, this is a WW1 fighter and not an indoor 3D model ! A real Nieuport didn’t even have the luxury to throttle back, the only way to come down was by using a “blipper switch” on the stick to completely eliminate the ignition. The engine kept turning due to its windmilling prop and huge inertia (rotating cylinders!). My model was very representative for that type of engine management so I neglected their comments and made two more flights exploring the flight envelope at slightly different speeds, executing turn reversals and patterns in the opposite direction. I’m convinced besides being the most attractive model of our club, it’s the best indoor flyer I had so far.

Notwithstanding the huge aileron to rudder mix, it still demands appropriate minimum speeds. Getting below it rapidly gives visual signals that it doesn’t want to respond to ailerons anymore. Persevering probably would result in tip-stall. Recovery at the first symptoms (by just minimal release of aileron input and relaxing the back-pressure, is straightforward).

After further trimming, the model proved very rewarding and not so difficult to fly in those small confines, I will not change anything to that model anymore and am fully happy with my lightweight aileron conversion. The only thing I did, was apply some liquid rubber around the tailskid to prevent the model from making pirouettes after landing or during taxi. That Nieuport 17 is definitely the kind of model I feel comfortable with in our small sports hall, and I ordered another pre-WW1 model (this time in traditional built) to join the fleet during winter 2015-2016. The flights I also did on the same date with the Acro Magnum went fine, it proves that for me that ailerons are a must.

A week later Phaedra had her camera to witness the maiden of her Twin Otter, but also took the opportunity to film my Nieuport 17. I made a couple of flights that day, but later got a midair with another model, and his prop sliced through the leading edge of my wing. I landed uneventful, and thanks to clubmembers suggesting me to pick up the pieces of Depron from under the crash area, I got the model ready for action the same evening, with minimal damage to the looks and integrity. Here is the short video of the previous flight.
Nieuport ailerons (1 min 25 sec)
Last edited by BAF23; Dec 07, 2014 at 06:04 PM.
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Dec 03, 2016, 09:07 AM
The sky is the limit
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Nov 2016 cosmetic changes

I loved the looks of my old Belgian semi camouflaged Nieuport and the flying qualities of my modified later model. Although end 2016 I hadn't flown it for more than a year (I got tired risking my indoor models in the midst of crazy flying people in a too small indoor venue), I automatically looked at it a few times a day, hanging from the ceiling of the dining room. In-between model restorations I took it off the hook and decided for a makeover of the still standard e-flite looks . The limiting factor for that model was weight, this time no more preparation with filler and relatively heavy painting. I therefore opted from an early war scheme of a 1st Belgian Squadron, before they later painted the upper surfaces green to minimize the reflections as seen from above against the Flanders' fields.

The wings could thus remain intact and change of the 6 French marking into Belgian ones by keeping the original red outer rings, but brushing kid's water paint yellow over white and black over blue to change them into the 6 Belgian wing markings. This required the removal of some of the clear tape I used as hinges for the added aileron mechanism but that went well using a scalpel. The same recipe was applied to the tail colors, and a thin marker pen used to apply the period N5021 factory follow-on number. The French markings all around the fuselage were half adhesive/half glued and impossible to remove without traces from the silver sprayed thin Depron fuselage sides. I already was lucky not to tear the Depron apart and resisted trying to correct the damage. The self adhesive red comet markings I had made for the first model came off relatively easy and were applied on the second model. These did not cover the damaged sides completely but attract so much attention that people don't seem to observe the damages anymore.

I also swapped the red/silver engine cowl for the silver one I had made a few years ago. The prop was removed and using flowing through eachother shades of brown plastic paint I was able to reproduce the looks of a wooden prop. Last but not least the Lewis gun on top of the wing was removed and replaced by a modified barrel gun that was glued on top of the front fuselage, as mounted on all Belgian Nieport 23 models of nr1 sqn. This is not a true scale model but now at least doesn't look like all the other thousand of other e-flite models anymore. Not that I am fanatic, but I prefer to see a representative Belgian historic aircraft than a French machine in my daily living room. All systems and electronics were checked again and this nice indoor model is ready to take the skies whenever I feel like it again.

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