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Sep 24, 2020, 02:38 PM
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Build Log

Fly-Fly F100F, rebuild of a sad looking second hand EDF model


Pic 17oct20-3


Rationale

In 2014 I stumbled upon an advertisement of a second-hand Fly-Fly F100 in flying condition for what seemed a reasonable price. Some time before that I already had purchased one of the last original kits of that brand because I ever wanted to make a nice model of the French Air Force two-seater I had the chance to fly just weeks before it was phased out. Even as the second-hand one was in a sorry state, I bought it to use as a trainer and eventual source for spares if the need aroused. All of that laid dormant together with other kits and aircraft on my attic for years. End of summer 2020 I had a two week lul in my program and thought that getting the second-hand one ready for some test-flying with various EDFís I had collected would be a useful way of filling that time. Once in my workroom I was very disappointed about the way that model had been very grossly assembled and decorated. The guy I bought it from had been a firefighter at the airbase of Beauvechin and should at least have been familiar with the fact that the USAF star stood on two legs instead of on its head!

Pic 0017c


Speaking of legs, when you see how the nose-gear had been fastened to the fuselage you get an idea about the craftsmanship? of that modeller. I think he used a complete jar of Gorilla type glue on that model. Furthermore duct tape had been used to cover other atrocities before being painted, and during sticker application he had not followed the deep crease lines and after they became loose he used clear Scotch tape to keep the ends flat!

Pic 0024c


Dismantling the sorry looking bird revealed even more unpleasant surprises. The wiring was a mess, with lots of extra bits that had been added in an unprofessional way, and a cheap HK servo-reverser for the moving stabs. The ESC had been just glued to the roof in front of the fan-case that had been very unprofessionally installed in very roughly scraped out foam. The fan itself was extremely deteriorated and I wonder how much air it still moved. Obviously that damage could not have been caused from operating on the military runway as he claimed. Having no nosewheel steering he obviously ended-up in the surrounding clay soil, or crashed into it.

Pic 0029c


Whatever air it moved aft still had to find its way through a very turbulent aft fuselage, marred by all kind of obstructing wiring and plugs that had been glued at places that were difficult to reach for complete removal. A look through the exhaust from where the EDF-unit had been, you can imagine it wasnít easy to separate all that wiring and plugs from the inside of that long tunnel.

Pic 0031c


I then made an inventory of the electronics that I found or extracted:
Rud + ailerons: 9gr Hextronic hxt 900 1,6kg-cm
Ele: 2x13gr Turnigy 9018mg 2,5kg-cm miniservos
Gear: EPF DSR46T assembly and controller (min 6V), non-steerable nosewheel
EDF: 90mm Taft 11 blade, Kv1450, 6S, 316gr, 3,2kg at 98Amp
ESC: Hobbywing Flyfun 100A opto 2-6s

Options

Could the model be saved? Yes. Could the model be useful? Yes. Could the model be restored to an acceptable standard? Difficult, but it could later possibly serve as a base for a unique project I had in mind since I saw a real F107 at the Pima air museum, but that will eventually be for much later, it first needed to serve as a trainer and testbed. I decided to start with a general cleanup of the mess, then install a new fan in the shroud, install new wiring and making the nosewheel steerable. At that stage things just had to be working, not really look good. After test-flying and acquainting with this second-hand model, the brand-new kit will be assembled much more scale with the settings I found out on this one. On various Forums I read that people moved the main gear forward and some even the entire wing. This old ungainly thing was exactly what I needed to butcher. Butchering was exactly what I did for two days, thatís how much time I needed to just remove all the excess glue inside and outside the foam, plus most of the wiring. That was necessary to allow the air from both the intake and cheater hole to flow smoothly with minimal interruption into the fan and back out the aft exhaust. To avoid damaging the fan on the ground, a FOD screen will also be mounted in the cheater hole.
As most of the decoration was barely holding, it was completely removed. The factory cg of 265mm was reported to be too much forward, for the 280mm mark (preferred by many modelers) batteries had to be moved very much aft. I therefore elected to move the EDF assembly as much aft as I could and that meant against the wooden part that form a short aft wing spar and keeps the wings together at the correct angle. The ESC position was chosen just aft of the EDF, under its intended wooden frame and cooled by the exhaust. That wooden plate has more cooling slots and above it is a tunnel originating behind the battery room. By making adequately sized fresh air holes forward of that, it only serves it purpose when the hot air can escape. I therefore opened a channel between the two upper parts of the exhaust tunnel, also useful to contain the wiring to the tail out of the exhaust flow. All that was essential in my mind so I could obtain and assess the true maximum power the EDF assembly produces on this light but large model. The possible excess power can then be used later on to guess how much extra weight can be added on the new F100 to make it more scale (ie flaps, airbrakes, burner ring, decoration etc). As I intend to use a powerful 6S5000 60c battery, the 100Amp ESC offered too little overhead capacity so I switched to a HK RotorStar120Amp (130 for 10sec) with 12Amp SBEC that I had in stock.

Reassembly

Having a complete Taft 90mm EDF plus a spare 11-blade fan in stock I opted to mount only the latter in the cleaned and sanded existing shroud and motor (keeping the new one for another kit. Having no special equipment I only could balance the rotor statically. After mounting the shroud I used scrap foam and lots of foam filler to contour the intake and exhaust ducts to allow a fluid airflow. As I was afraid that chunks of filler could come loose and damage the fan, I coated the entire intake duct with Z-poxy. I partially removed the wrap around the ESC to allow more cooling air to flow over the finned area and modified the wooden cradle for the third capacitor (and as such the entire unit) to sit deeper with just the fins sticking out into the exhaust.The ESC is kept tight against its wooden support by two nylon straps.

Pic 0034c


A lot of time was spent to completely redo the wiring to eliminate doubtful connections and have everything entirely out of the way of both intake and exhaust. Using a long chisel from the inside of the fuselage I was able to open up the a free channel under the fuselage spine, from aft of the cockpit till under the rudder, that's the space they use in the real aircraft for the plumbing and wiring as well. A long piano wire with a hook was used to pull all the wiring through it. I kept individual wires for each elevator so I could later program a mix with the ailerons to see if the latter could be eliminated and still have roll control (the F107 had no ailerons, only spoilers). Together with the rudder servo wire, all three were plastered in the spine above the exhaust with lightweight filler to obtain a perfect circular obstruction-free exhaust tube.

Pic0040c


Both aileron and main gear wiring were joined in a kit-provided cavity under the EDF shroud and JR connectors (one male and one female to avoid the possibly of misconnection between ailerons and gear) soldered so the wing can be separated from the fuselage for maintenance or stockage. By reversing the ESC it was easy to route the 3 wires to the engine in the cavity on top of the EDF where the connection can be hidden and only a short 180į loop of the EDF-side so wires lay flat against the exhaust tube. Throttle control and ESC program wires were the routed on top of the ESC wooden support onto the tunnel towards the cockpit, together with the 12AWG power wires. The tunnel under the spine also houses the FrSky old FAS100 power sensor and vario-converter for the telemetry.

Pic0038c


All those servo wires were bundled together with loose nylon straps that I pushed deeper into the fuselage so everything could be orderly kept into position behind a custom wooden vertical separation wall (along the right side) to separate the electronic signals as much as possible from the battery and battery wires.

Pic0072cr


The way the landing gears had been bolted to many layers of grossly glued external wooden plates created excessive drag, also because the main legs protruded fully in the airstream. Turning those around was not possible so I first grinded away all the excess wood and made new plates so I could mount the 3 gears deeper into the fuselage (after carving out some extra foam for the mains). I installed a steerable nosegear but couldnít find an appropriate compressing oleo with twin wheels so I went for a rigid single wheel for the time being. Everybody who had FlyFly models remember how deep and wide the panel lines were cut in the foam. These not only look awful, but together with the deep wing pylon receptacles in the wing probably create an enormous amount of drag. Painting such surfaces with a roller or brush would be difficult and I try to avoid aerosol spraying in my apartment. After filling the largest cavities with scrap foam, I used 2,5 tubes of lightweight filler to equalize the surfaces of the entire model (using an old credit card to spread the filler flat).Those panel lines were so deep that they needed 3 layers to fill flush.

Pic0042c


Pic 0044c


By that time the model looked too bad to be flown as such but I didnít want to invest in fancy decoration either. Still undecided about the paint scheme I applied gray primer over the entire model and that helped me accept the fact that even if the model was aerodynamically already much cleaner, it would never look really good because of the bad work the previous owner had delivered.

Pic 0058c


After searching for easy to reproduce but well visible color schemes I decided to portray one of the many surplus F100 that were converted to QF100 drones to end their lives being shot at. They took more than 200 F100D and Fís out of the bone-yard, flew them to Mohave to be converted to drones. That is where they added the remote control capability but as their average lifespan would be around 10 flights (being shot at by missiles or guns, both from the air of from the ground), they kept the original dirty faded-away camo to which bright red plain nose, wingtips and tail decoration was added. They then were flown in a normal way to Tyndall AFB (and later (Holoman AFB) to be abused without a pilot sitting in it.

Pic TyndalAFB


As the old basic colors could be much different from the standard Vietnam scheme, I used various leftover paints to create that weathered effect. I also used this model to experiment how to achieve a realistic result of the much discolored natural metal around the exhaust section of the engine.

Pic 89710_1509897845c


Working well was using Humbrol copper paint to which immediately after it was applied, a stripe if thin blue color was applied in the middle. With everything still wet, chrome paint was applied in between and lightly over the copper area. All this was done solely using brushes and I am satisfied about the result.

Pic 0069crr


After installing the X8R receiver from my crashed Boeing (test-flown for security in a Parkzone Ka8 glider for functionality) I was able to program and connect everything. That is when I started doubting if that model ever had flown decently. The elevator throw was twice what was suggested with a questionable neutral point, the ailerons only had half the required throws! I rearranged all the mechanical linkages to obtain symmetrical throws and used Locktite to fasten the multiple adjustment screws. I then test ran the EDF combo and was happy to read 98Amps with 21V meaning 2000Watt which should be sufficient for that 3,3kg (incl batteries) model. The correct balance could only be achieved with a 6S4000 60c battery (not the 6S5000 as predicted) as deep as could be pushed into the compartment. For safety I have an emergency 2S950 batterie delivering power to the receiver through a diode in case the BEC of the ESC fails. In fact the whole nose compartment remains empty (except for the receiver), but at least I didnít have to add weight in the tail, but changing and connecting the batteries was anything but handy. During the engine runs I noted the ESC came pre-programmed with a heli startup mode. None of my 5 program cards worked for it and nowhere on the net could I find the manual programming sequence of beeps in order to do it via the transmitter. I had no other choice than order it through Hobby King, a store I had been able to avoid for years.

A few days later I got the programmer but without instruction manual, just as I received none for that ESC years before, one of the reasons I ban that firm from my list. After viewing a few you-tube amateur incomplete tutorials I attempted the re-progamming, only to find out that I couldnít do it through the intended (second) programming wire I had easy acces to. There was nothing else that I could do but dismantle the model, remove the motor and take the ESC out of it, reprogram it and reconstruct the full the entire wiring loom running through the fuselage spine. I got it done just hours before the last summer-flying weather turned over to stormy fall conditions. I then immediately left for the field to testfly it.

Maiden flight

Pic 0068crr


After tweaking it here and there I lined it up for its maiden. I was disappointed about the acceleration on the grass but thanks to its nose-high stand on the tall nose-gear and despite the exaggerated aft position of the main gear, it left the ground at less speed than anticipated. Unfortunately, the speed didnít increase much anymore but sufficient for the climbing turn to downwind. Even after level-off under full power the speed remained rather low. Throttle changes produced a change in noise, but had little influence on airspeed and after trimming 5 clicks up, I turned back inbound to observe gear retraction. That helped a bit and I further climb was initiated to perform some handling.

Response in pitch and roll was adequate and no nasty behavior was found during steep turns, even at slow-speed. When sufficiently high I reduced the throttle to perform level stalls. I was surprised how slow the model could fly but when it stalled, pitch as well as bank brutally kicked in resulting in serious height loss during recovery. I came back down and lowered the gear in front of me, confirming all 3 were down. The first pattern proved simple but two more low approaches were flown before I felt I was in the condition to land. 6-feet high crops either side of the field reduced the practical field-length and caused a steeper than desired glide-angle to be flown. By that time my telemetry told me I had used most of the battery so even after the flare caused the model to slightly climb, I continued maintaining the attitude (I didnít want to touch nose-wheel first) and when the F100 came back down I tried to reduce the sink rate by giving it a throttle burst. That helped but was insufficient, just as was the battery capacity and remaining runway length to go around or stretch the landing much further by another power application. The result was a rather firm touchdown with the model having difficulty in taxiing under its own power.

Whilst others congratulated me for a maiden without crash, I definitely was not happy about neither the flying quality of the plane, nor my heavy landing. Upon picking it up I saw both main gears legs were twisted about 20į inboard and back at the much too weak and soft 3mm pins. No other damage was observed and the battery felt rather hot but still had 22į capacity. To me the model is too large and draggy for the 6S 11-blade 90mm EDF combination and even with the cheater-intake, is not able to move sufficient air around. The aftermarket main retracts the previous owner installed were not suitable for a 3kg model because they were very easily bent back into position just by hand. The 280mm CG worked well, just as the suggested control throws, but the full flying stab is very sensitive and 25% expo seemed insufficient for scale flying (increased to 35% for second flight). Getting the battery in and out of the long aft cave is cumbersome and cooling still seemed problematic.

modifications after maiden

I started by correcting the landing gear, something I should have done from the start. Not wanting to modify the wing I had no other solution than to dismantle the main gear without extracting it completely from its location. I was able to unscrew everything whilst keeping the wire connected, intact and embedded in the well. I then unscrewed the gear legs and cleaned the spring mechanism to regain smooth operation. I then tested the compression on the scales and noted a required 2kg of pressure (each) to push them in, that seemed barely sufficient for a 3,2kg plane. The weak 3mm pins between the trunions and legs were seriously bent and thrown away.

With the spring removed I drilled out the bore for the pin from 3 to 4mm. With the retract mechanism barely out of the well I unscrewed one side of their metal body whereupon it was easy to remove the trunion without having to dislodge the motor nor drive-shaft. I clamped it that so I could use the column drill to also bore it out to 4mm. I then took spare 4mm hardened-steel motor shafts out of my stock and marked the areas where the fastening screws touch and flattened those areas for stronger grip and eliminate any pivot.

After assembly the legs were further flattened where clearance was too tight with the retract motors (and caused occasional jamming). This was also done on the nosegear but as that already came equipped with a 5mm pin, nothing else than local flattening of that pin needed to be done. As the 65mm main wheels wobbled too much on their axles I replaced them by 70mm lightweight wheels that were mounted on a copper bushing. After thoroughly testing the gear I was convinced it was up to the job and would tremendously improve the ability to absorb the strain of takeoff and landing on grass surfaces and all this at no cost and negligible weight increase. The starboard gear retraction sometimes is very noisy and seemed to be seriously worn but probably capable will have to do some more flights if retracted at 1G.

With the model upside down I also saw the archaic way the builder had connected the flying-stab push-rods, and after a quick-fix on the field before the maiden, I decided to tackle that problem. When replacing the all too soft z-bend ones by straight kwik-link actuators I also removed the long filleted bellcrank screws and discovered one grabbed on an axle that had been more than halved in an attempt to flatten it and on the other side the fillet in the holding collar had worn out (by over-torque) and was barely holding. That was when I realized I had been extremely lucky during that maiden, and wasnít taking anything for granted anymore on that poorly assembled model.

While testing for adjustments using only the backup battery I encountered occasional power ruptures. Closer investigation revealed the wires coming out of the Castle CC10 BEC had been squeezed to much getting it in and out of the wire tunnel next to the battery, that it allowed intermittent contact between the red and the black. The diode downstream probably saved me from another disaster. After re-soldering and isolating those wires I decided Iíd had enough of all that fumbling around and squeezing, and cut a large hatch in the modelís spine to facilitate battery changes. That allowed the battery to be mounted facing aft and extra length of heavier batteries wonít affect the CG much. It also allowed me to substantially shorten the power leads, the 17cm that I eliminated drastically reduced the burden on the ESC capacitors. Some adaptations had to be made again to keep the wiring separated and assign a permanent spot for the emergency power battery under the canopy. Because I do not perform negative G maneuvers and the way my extra battery hatch is secured front and back, I did not see the need to secure the battery with an extra strap. I also cut additional tilted vent holes on the aft sides of the hatch to help evacuate battery heat.

The maiden proved the power setup to generate ample airstream to get airborne and climb, but insufficient efflux to obtain a normal forward speed. The stock exhaust diameter of 85mm confirmed my theory and I calculated the optimum diameter to be 76mm (85% FSA). As both are dependant on each-other I prefer to sacrifice a little max thrust to get more efflux and hopefully gain some speed. I do not expect miracles on this much too large draggy model but hoped a thrust tube would make things a little better. I used a 20x30cm 0,5mm white (couldnít find black) polystyrol sheet that I rolled up and inserted through the exhaust up to the traverse elevator rod. At that side it is allowed to freely push against the walls and as such lay flat against them for a smooth airflow transition. At the exhaust side I used tape all around it to roll it to a perfect 76mm diameter. Using tape will allow me to further experiment with different diameters during further test-flying. That was also the reason why nothing was glued at that stage. Rubber draft isolation around the back of the tube and two smal screws from the inside into the old exhaust kept things in position for the following test flights. Losing the tube in flight wouldnít cause a disaster either, Iíd just land as on the maiden with even sufficient thrust for a go-around.

I also noted the 1450kv motor only could generate 30500rpm which is rather low, even for an 11-blade fan. I later might try the E-jet 1865kva EDF of my Viper to check the effect at 39000rpm. In order to get a bit more ram-air in the nose intake I cut the plastic off the inside of the thick lip and also thinned the foam wall at the front, effectively gaining some airflow. All was flattened with filler and hardened with Z-poxy finishing resin. That was also applied to the sides of the extra battery hatch after which touch-up paint and varnish was applied. I then test-ran the model at full power to verify that the thrust tube remained in position without collapsing. Next I adjusted the CG for using the shorter 6S4000 and the longer 6S5000 batteries in different aft foam cutouts. The fwd battery block remains in one position but the emergency 2S950 battery is moved to different positions to further compensate.
All the modifications in this post-maiden refurbishment entry only amounted to a mere 20gr extra weight.
Last edited by BAF23; Yesterday at 02:16 PM.
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Yesterday, 03:08 PM
The sky is the limit
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Thread OP

Trials after the maiden


modifications after maiden

I started by correcting the landing gear, something I should have done from the start. Not wanting to modify the wing I had no other solution than to dismantle the main gear without extracting it completely from its location. I was able to unscrew everything whilst keeping the wire connected, intact and embedded in the well. I then unscrewed the gear legs and cleaned the spring mechanism to regain smooth operation. I then tested the compression on the scales and noted a required 2kg of pressure (each) to push them in, that seemed barely sufficient for a 3,2kg plane. The weak 3mm pins between the trunions and legs were seriously bent and thrown away.

With the spring removed I drilled out the bore for the pin from 3 to 4mm. With the retract mechanism barely out of the well I unscrewed one side of their metal body whereupon it was easy to remove the trunion without having to dislodge the motor nor drive-shaft. I clamped it that so I could use the column drill to also bore it out to 4mm. I then took spare 4mm hardened-steel motor shafts out of my stock and marked the areas where the fastening screws touch and flattened those areas for stronger grip and eliminate any pivot.

After assembly the legs were further flattened where clearance was too tight with the retract motors (and caused occasional jamming). This was also done on the nosegear but as that already came equipped with a 5mm pin, nothing else than local flattening of that pin needed to be done. As the 65mm main wheels wobbled too much on their axles I replaced them by 70mm lightweight wheels that were mounted on a copper bushing. After thoroughly testing the gear I was convinced it was up to the job and would tremendously improve the ability to absorb the strain of takeoff and landing on grass surfaces and all this at no cost and negligible weight increase. The starboard gear retraction sometimes is very noisy and seemed to be seriously worn but probably capable to do some more flights if retracted at 1G.

With the model upside down I also saw the archaic way the builder had connected the flying-stab push-rods, and after a quick-fix on the field before the maiden, I decided to tackle that problem. When replacing the all too soft z-bend ones by straight kwik-link actuators I also removed the long filleted bellcrank screws and discovered one grabbed on an axle that had been more than halved in an attempt to flatten it and on the other side the fillet in the holding collar had worn out (by over-torque) and was barely holding. That was when I realized I had been extremely lucky during that maiden, and wasnít taking anything for granted anymore on that poorly assembled model.

While testing for adjustments using only the backup battery I encountered occasional power ruptures. Closer investigation made clear the wires coming out of the Castle CC10 BEC had been squeezed to much getting it in and out of the wire tunnel next to the battery, that it allowed intermittent contact between the red and the black. The diode downstream probably saved me from another disaster. After re-soldering and isolating those wires I decided Iíd had enough of all that fumbling around and squeezing, and cut a large hatch in the modelís spine to facilitate battery changes. That allowed the battery to be mounted facing aft and extra length of heavier batteries wonít affect the CG much. It also allowed me to substantially shorten the power leads, the 17cm that I eliminated drastically reduced the burden on the ESC capacitors. Some adaptations had to be made again to keep the wiring separated and assign a permanent spot for the emergency power battery under the canopy. Because I do not perform negative G maneuvers and the way my extra battery hatch is secured front and back, I did not see the need to secure the battery with an extra strap. I also cut additional tilted vent holes on the aft sides of the hatch to help evacuate battery heat.

The maiden proved the power setup to generate ample airstream to get airborne and climb, but insufficient efflux to obtain a normal forward speed. The stock exhaust diameter of 85mm confirmed my theory and I calculated the optimum diameter to be 76mm (85% FSA). As both are dependant on each-other I prefer to sacrifice a little max thrust to get more efflux and hopefully gain some speed. I do not expect miracles on this much too large draggy model but hoped a thrust tube would make things a little better. I used a 20x30cm 0,5mm white (couldnít find black) polystyrol sheet that I rolled up and inserted through the exhaust up to the traverse elevator rod. At that side it is allowed to freely push against the walls and as such lay flat against them for a smooth airflow transition. At the exhaust side I used tape all around it to roll it to a perfect 76mm diameter. Using tape will allow me to further experiment with different diameters during further test-flying. That was also the reason why nothing was glued at that stage. Rubber draft isolation around the back of the tube and two smal screws from the inside into the old exhaust kept things in position for the following test flights. Losing the tube in flight wouldnít cause a disaster either, Iíd just land as on the maiden with even sufficient thrust for a go-around.

Pic 17oct20-4cr


I also noted the 1450kv motor only could generate 30500rpm which is rather low, even for an 11-blade fan. I later might try the E-jet 1865kva EDF of my Viper to check the effect at 39000rpm. In order to get a bit more ram-air in the nose intake I cut the plastic off the inside of the thick lip and also thinned the foam wall at the front, effectively gaining some airflow. All was flattened with filler and hardened with Z-poxy finishing resin. That was also applied to the sides of the extra battery hatch after which touch-up paint and varnish was applied. I then test-ran the model at full power to verify that the thrust tube remained in position without collapsing. Next I adjusted the CG for using the shorter 6S4000 and the longer 6S5000 batteries in different aft foam cutouts. The fwd battery block remains in one position but the emergency 2S950 battery is moved to different positions to further compensate. All the modifications in this post-maiden refurbishment entry only amounted to a mere 20gr extra weight.

Second flight

Two weeks later I took the model to the field on a very calm but cool and murky day. Before the big bunch arrived I already maidened my Funcub XL and being quick get another Super Sabre short test done. The idea was to mainly check what the modifications did to the forward speed and how the strengthened gear coped with the anything but manicured grass. I can really recommend you to build the gear so the model has a nose high attitude on the ground, even more pronounced than that of the real aircraft. The benefit of that is even with the factory positioned too much aft main gear, the model takes-off from itself, hardly needing a rotation.

Pic foto 17oct 20-5cr


Ground roll just was a tad longer and this time I immediately retracted the gear. I was very satisfied to see it climb out with an adequate speed. During the two circuits at medium altitude I checked how much I could throttle back without losing much speed. Three quarter throttle seemed ok, all above that was only good for climbing but the drag of the aircraft was preventing it flying much faster. The dark sky made it difficult for me to see the modelís bank attitude, something I hadnít expected with the pronounced difference between the pale bottom and dark top of the wings, Iíd definitely needed to pay a visit to my eye-surgeon. As I got scared about that I came back down for a clean pass revealing a much higher speed that during the maiden, intake and exhaust changes proved to be very effective. I then lowered the gear and made a first low approach to observe things (gear and thrust tube) and verify the go-around power.

Pic 17oct 20-2ccrr


I then set up for a standard closed pattern and a final with the nose slightly high (as I didnít want to touch nosewheel first). During the flare I was astonished again to see that the nose could be raised very high before the model sank or settled, suggesting a much lower approach speed could be used in the future.

Pic17oct 20c


Taxiing back on the uneven grass was bumpy but I was glad to see after the flight that the gear hadnít moved a bit, the 4mm gear-pins were adequate. After only two flights that FunFun F100 seemed adequately set up for flying the following spring.

Here is the movie of that second flight
F100F FlyFly RC model second flight (2 min 23 sec)


Lessons learned for next F100

Enlarge and thin nose intake, install heavier EDF or move it more aft, main gears to be positioned 6cm forward will help for rotation, rudder and flaps not necessary, elevator servoís to be moved to underside of fuselage (metal gear digital). Reduce drag of wing and tail surfaces with balsa trailing edges. Rearrange cockpit seats but keep nose light. Install burner ring in tail, make new battery hatch above fuselage well aft of canopy. Reduce exhaust diameter from 85 to 76mm, eliminate wingtip light covers,
Yesterday, 03:11 PM
The sky is the limit
BAF23's Avatar
Thread OP

Technical recap figures


Technical recap

Dimensions: length: 160cm, span: 125cm, height: 45cm
Empty weight: 2660gr, batteries: 6S4000 60c + 2S950= 670gr
Takeoff weight: 3330gr. Wing load 95gr/dm≤
CG: initial 280mm , final 280mm
My final throws: Ail: +20 -20mm, Ele: +25mm -25mm , Rud: mm L&R
Motor: EDF: 90mm Taft 11-blade, Kv1450, 6S, 316gr, 3,2kg at 98Amp?
Ground full power static figures on telemetry: 21V - 98A = 2000W
ESC: HK RotorStar120Amp (130 for 10sec) with 12Amp SBEC
Servos: Elevators: 2x13gr Turnigy 9018mg 2,5kg-cm.
Ailerons, rudder : 9gr Hextronic hxt 900 1,6kg-cm. NWS: HK929MG 2kgcm
Aileron expo: 25% and no differential, elevator expo: 40%, NWS expo : 80%
Paint: Under: ral 1015, Tan nr 93, light green nr 117, dark green nr 30, red: ral 3020


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