JasonK
Participation Award Recipient
- ~100g kfm wing (own design)
- FT mini-F22
- ~250 kfm wing/FPV (own design)
- STOL V-tail ?Trainer? (own design)
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FTFC21: Build-ruary by JasonK (Build Skill: 4, Pilot Skill: 3)
- Thread starter JasonK
- Start date
JasonK
Participation Award Recipient
~100g kfm wing
Picture, plans link, why chosen
plans: see build log, this is a custom design for this challenge.
I picked this design because I wanted to try a kfm wing, needed a replacement for a crashed FT dart, and after cutting the main wing and peeling removable paper, found that with the correct parts, this could hit about 100g (less, but just over with the parts I have handy).
Build Log
I started with mocking up the wing in ecalc, with a few modifications to have room for a 6in pusher.
Extra measurements needed beyond the ecalc layout
Maiden Video
flight notes:
Post-Project Reflection
Picture, plans link, why chosen
plans: see build log, this is a custom design for this challenge.
I picked this design because I wanted to try a kfm wing, needed a replacement for a crashed FT dart, and after cutting the main wing and peeling removable paper, found that with the correct parts, this could hit about 100g (less, but just over with the parts I have handy).
Build Log
I started with mocking up the wing in ecalc, with a few modifications to have room for a 6in pusher.
Extra measurements needed beyond the ecalc layout
- Fold over 3.5" in the center, 2" at wing tips.
- Elevons are 0.5" at the wing tips.
- winglets -> 2" tall, 4" long end, 1"x1" diagonal out of rear bottom, top is 2.5"
- 1 sheet DTFB (I used Ross, slightly heavier, but stronger)
- 1 BBQ Skewer
- Gorilla Glue (Optional - used were possible to reduce weight)
- Hot Glue
- Receiver
- 2s 650mAh battery (smaller would is likely fine, this is what I have)
- 2x 5g servo
- 2x pushrods
- 2x control horns
- 1106 4500kv motor (FT gremlin)
- motor mount
- ESC/BEC
- Mirror the fold over parts at the fold over then cut out.
- double bevel cut both at the fold over point and at the elevon joints
- remove paper were the foam will contact itself
- cut 11" BBQ skewer
- score 11" channel centered on the wing 3.5" from nose to press BBQ skewer into
- place BBQ skewer in channel and fold over both wing edges to lightly indent were the BBQ skewer lines up, then lightly score and indent
- Glue fold over parts down with gorilla glue (or glue of choice) with BBQ skewer in place.
- Reinforce hinges with hot glue
- Glue on winglets
- cut out servo mounting points, I measured 4" from the center line just behind the BBQ skewer, draw a 1/2" back (so from 3.5" to 4" from center), place down servo, trace out, then carefully remove 1 layer of foam. I had to partially cut one of the mounting bits off the servos to be able to put the servos fully in, as the BBQ Stick was in the way and I didn't want to break the Stick for the servo. This placement of the servo, gets it almost on the CG, which given the shape, most of the non-wing mass will need to be in front of the CG target to get the CG at the desired location (3.75-4.00" in from the nose).
- Glue in the servos and control rods
- setup pushrods to give 1 thickness of foam-board of reflex (this is currently a guess for how much is needed)
- solder up/prepare electronics (varies depending on exact choices)
- mount motor mount on the top middle of the craft, as far forward as possible, while giving a small amount of room for the prop.
- Mount remaining electronics so that the CG is in the correct place, I left a bit of room in-case I wanted to put a micro FPV AIO on the nose.
- I mounted my battery to the bottom with velcro, giving the most ability to adjust CG by moving it possible.
Maiden Video
flight notes:
- Flight 1 -> mess up the elevon mix and had roll backwards.
- Flight 2 -> needed increase in elevator deflection, didn't have very good pitch control.
- Flight 3 -> had upped both pitch and roll gains and moved the CG back, got to sensitive in roll
- Flight 4 -> removed the extra roll dual rates, trimmed some roll and pitch before launch and flew fairly well.
Post-Project Reflection
- Time Taken
- Cutting out: 30m
- Assembly: 2h (less if you don't need to solder up your electronics)
- Painting: 30m (mostly hand painting time)
- Dry Weight: 108g
- AWU w/ 2s 650mAh Lipo: 146g
- Build Difficulty: low
- Flight Difficulty: low-medium (flies nice, but hard to track in the sky - at least with the current paint job + the time the maiden was done)
- strip paper after doing bevel cuts (I have a jig that makes them fairly easy, but pulls at the foam if not covered)
- block painting in sub assemblies can make some painting work much easier
- the fold over of the kfm wing needs lots of pressure to hold in shape while the glue is drying, I needed to use a board with 10+ lbs of weight on it to hold the wing flat while the gorilla glue was drying.
- One thing that I have found that I don't like with wing/wing like flight things is that it seems like there is a big thrust and/or speed impact to pitch. With the motor mounted above the wing with no down angle, I expected to have issues with thrust pushing the nose down, but I didn't have any issue like that. I did however have issues getting the pitch trim done well, perhaps a throttle thrust -> negative elevator mix would improve this.
- Durability is great, multiple landing, some of them rather rough and no viable marks/damage that I could find to the wing itself.
- After getting the dual rates/trim/etc setup close to what was needed it flew rather nicely.
- One thing that I ran into was 'flying on the wing' as basically everything I have flown before now was at 1:1 or better thrust:weight ratio, which being able to push your motor to 100% and forcing your way out of a situation is definitely different then being 100% reliant on the lift from the wing working as expected.
- The plane seems to have quite a bit of drag, this is probably a mix of all of the exposed electronics and possibly the kfm wing shape.
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JasonK
Participation Award Recipient
FT mini-F22
Picture, plans link, why chosen
plans: FT mini-F22
I chose the FT mini-F22 as it has been my son's favorite thing to fly and the one we have is damaged in a way that isn't readily repairable.
Build Log
Maiden Video
Video is rather unimpressive. I through the plane into the air, my son tried to level it and give power and it just rolled left and nosed down. Thankfully the airframe damage is reasonably easy to fix, but either the motor or ESC got taken out (motor just twitches now)
Post-Project reflection
Picture, plans link, why chosen
plans: FT mini-F22
I chose the FT mini-F22 as it has been my son's favorite thing to fly and the one we have is damaged in a way that isn't readily repairable.
Build Log
- Print out plans, cut out templates and tape together
- Tape down on DTFB and cut out
- Paint pieces
- Assemble per FT instructions
Maiden Video
Video is rather unimpressive. I through the plane into the air, my son tried to level it and give power and it just rolled left and nosed down. Thankfully the airframe damage is reasonably easy to fix, but either the motor or ESC got taken out (motor just twitches now)
Post-Project reflection
- Time Taken
- Cutting out: 2h 15m
- Assembly: 1h 30m
- Painting: 30m
- Dry Weight: 167g
- Build difficulty: low, just time consuming
- Flight difficulty: low
- If I had some sort of CNC cutter, I think I would enjoy complex curves and fittings more, assembling something like the FT mini-22 is rather easy, but printing/cutting out the templates, then cutting out all the parts gets rather tedious.
- I learned to keep my rattle cans upright, I accidentally purged the propellant on my grey can that was still a solid 50% full
had to improvise the other side of the main body (so I have some black on the bottom that I wanted grey). - Instead of cutting off the paper on the hatch, I used it to make a hinge, hot-gluing it down seems to have worked better then trying to bond a hinge with a piece of tape.
- I had an issue the servos vibrating, it seems that the mass of the elevon, etc was just right to cause oscillation in the servoes. A makeshift dampener taped over the push rod fixed this.
- Flight characteristics/experience is unknown as the plan never really became airborne under power.
- Plane isn't one to fly in the middle of strong gusty winds, it seems to be more impacted by the wind then many of my other planes.
- Dual rates could have been turned down some - at least on the roll, it was very roll sensitive.
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JasonK
Participation Award Recipient
Reserved for ~250 kfm wing/FPV
Picture, plans link, why chosen
I wanted to build an FPV craft in the sub-250g range, the wing size gives a WCL of ~9 for 250g which puts it in the acrobatic range. This scale should allow a flight controller, FPV gear and a 2s li-ion pack inside of 250g, which should give a flight time in the 30+ minutes range, while still having a 1:1 thrust:weight ratio with a 6x4.5 prop on the 1806. If this works out well, some experimentation with motors and props could be warranted to see if the motor weight could be brought down some.
Build Log
Maiden Video
Post-Project reflection
Picture, plans link, why chosen
I wanted to build an FPV craft in the sub-250g range, the wing size gives a WCL of ~9 for 250g which puts it in the acrobatic range. This scale should allow a flight controller, FPV gear and a 2s li-ion pack inside of 250g, which should give a flight time in the 30+ minutes range, while still having a 1:1 thrust:weight ratio with a 6x4.5 prop on the 1806. If this works out well, some experimentation with motors and props could be warranted to see if the motor weight could be brought down some.
Build Log
- follow instructions for ~100g kfm wing for the wing and servos themselves
- Alternate parts needed (using what I have on hand, if this works out well, some of these parts would be replaced)
- FT A pack motor
- FT A pack ESC
- 3s 650mAh battery (need the heavier battery to approximate the desired final characteristics)
- Motor Mount (designed for this craft)
- Additional parts needed
- AiO FPV
- Separate BEC for FPV gear
- Extra foam bits to close in equipment (detailed below)
- Cut out additional 'cover' bits
- glue on the sides
- glue on the top
- cut out small pass through for the servo leads into the pod
- wire up all the electronics in the pod
Maiden Video
Post-Project reflection
- Dry weight: 130g
- AUW with 3s 650mAh lipo: 184g
- Weight gives enough room for the desired 2s li-ion pack (comes in just over 100g) while still being under 250g, even with redesigning the pod(s) for the different equipment
- Final version (based on targeted goal) would likely have a bottom pod and little to no top pod as the flight controller/etc would all be rather flat and could be mostly burred in the wing itself. However enclosing the battery in a pod would be good for landings/etc, but not needed for this test.
- Not sure if I am nose heavy or the kfstep just had a really bad glide slope/to much drag. I lowered my throttle and nosed down and nearly dropped like a rock and when I gunned it when getting close to the ground, it took more to get going then my A-tail pusher did.
- oddly maidening in FPV was easier then LOS as I didn't have to worry loosing orientation
- I had to get creative to find a spot to maiden as the 'nearby' park I usually use had lots of people, so I had to use some off side bit of it, which limited the area in which I could test.
- I need to figure out if I have my CG off or if the kf wing just had much more drag then a FT style wing.
- I am looking forward to setting up something like this with a flight controller so I can get the stability and flight envelope improvements by having the FC making adjustments for reflex based on speed/etc.
- Roll and yaw stability felt really good - other then the above pitch trim/drag issues, it flow nice and straight.
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JasonK
Participation Award Recipient
STOL V-tail ?Trainer?
Picture, plans link, why chosen
This was the wildcard slot to pull in 4 total builds. Plans are below as this is another design specifically for this challenge. This will be my first plane with landing gear and ability to take off from the ground.
Build Log
eCalc CG Calculation
Parts/Equipment needed:
Maiden Video
Post-Project reflection
Picture, plans link, why chosen
This was the wildcard slot to pull in 4 total builds. Plans are below as this is another design specifically for this challenge. This will be my first plane with landing gear and ability to take off from the ground.
Build Log
eCalc CG Calculation
Parts/Equipment needed:
- Flaps Servo Horn
- 2x Motor Mount
- 4x Wing Mounts & Reinforcements
- DTFB
- BBQ Sticks
- 2x 1806 Motors
- 2x ESC
- BEC
- Receiver
- servos
- servo horns
- push rods
- battery
- various connectors
- Built Wing using standard FT method (measurements in photos)
- Cutout and build fuselage, rough measurements readable from images.
- Cutout 2 1" radius by 3 thickness tires and 1 1/2" radius by 2 thickness tires, glue together and paint black
- Calculate needed cutting for vtail, cutout, create angle to help support initial gluing into shape of the vtail itself
- attach vtail
- build wheel mounts
- Install control rods, servos, pushrods, & motor mounts
- Wire up power harness
- program TX mixes (this was a pain)
- Glue on wheel bits
- Balance
- Test fly
Maiden Video
Post-Project reflection
- Putting the wires in the wing before folding it over and gluing it shut would have saved having to fish the wires though narrow and long channels.
- I found that the wires on the motors I picked up were a bit fragile (at least at the ends- had one snap at the solder joint while bending it), so I didn't try to bend them around and 'tuck' them in behind the motor mount and just taped them in place, some pre-knowledge on this and I could have place a few things better)
- I am not sure how to setup up a throttle kill on my spectrum with the 2 motor channels like this, the 'throttle kill' setting will only kill the main throttle channel and not the secondary one.
- I really like the 3D printed wing mount brackets that I came up with, however they, as they stand, aren't something I would want to be connecting/disconnecting regularly. If I wanted to use them for that, I think some upgrades with screw mountings is what would be needed.
- Regarding the last item, after this build and others, I definitely like the idea of screw or other type wing mounts over rubber bands. Or at least with rubber bands, using something like this to stabilize the wing position, so it doesn't shift around and the rubber bands just hold it down, would work much better then just rubber banding on the wing.
- After programming up my spectrum to handle this setup, I am highly interested in trying out an openTX radio as, to my understanding, the mixing/etc is basically 100% under the purview of what you setup, there aren't any special functions to configure, but instead, just raw mixes (which as the mix complexity goes up, seems to be easier then working with all the settings in my TX)
- 472g AUW
- landing gear seems to have been undersized for the craft, or at least the surfaces I was landing on. I definitely need some practice landing with the landing gear.
- The flaps caused some interesting low speed/ground effect. One, I think I probably need some elevator mix in the flaps setting, but not 100% what exactly.
- The plan was trimmed out very nice for flight. I had did a click or two of left rudder and left roll after the first take off attempt (given that it wanted to roll when I was trying to take off) then it flew nearly hands off, to the point were I was able to look down at my phone an unlock it while it was flying.
- I had some trouble landing, but that might have been the elevator being to sensitive, causing over control in the pitch axis when trying to land.
- To make this a 'long term use' plane, I would want to redo the landing gear and improve access to the location were the battery goes to make it easy to put the battery in/out of the plane.
- I ran down my 5 minute timer on my plane and was still at 75% battery when I got home, so, at least for the casual flying I was doing, it I would expected a solid 10-15 minutes total flight time on the 1300mAh 3s battery that I had in it.
- Up off the ground, with the flaps all the way down, it slowed down really nicely, but I did need to keep the motors running, I believe the wing wanted to stall if I completely removed power with the flaps down.
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Fidget
Active member
Great designs! And I really like the way you lay out the project and description. I seldom have the discipline to write out what I would do differently next time.
JasonK
Participation Award Recipient
~100g kfm wing is done
FT F22 mini is done except for maiden and post maiden notes
~250 kfm wing/FPV is done except for maiden and post maiden notes
STOL V-tail ?Trainer? is in progress... just finished all the wiring, just need to mount the motors, test the directions, flip ESC -> motor wires if needed, connect push rods/control horns, handle the wing mounting/battery mount, then put on the landing gear and try it out...
ugg... I really need good weather when I am not working or sleeping or I might not get the maidens in in time
FT F22 mini is done except for maiden and post maiden notes
~250 kfm wing/FPV is done except for maiden and post maiden notes
STOL V-tail ?Trainer? is in progress... just finished all the wiring, just need to mount the motors, test the directions, flip ESC -> motor wires if needed, connect push rods/control horns, handle the wing mounting/battery mount, then put on the landing gear and try it out...
ugg... I really need good weather when I am not working or sleeping or I might not get the maidens in in time
JasonK
Participation Award Recipient
Hard to say.
The mini-f22 is one of my son's favorite and that was a rebuild because the old one was damaged in a hard to repair manner.
The h-pack motor wing was an interesting craft to try... for how low mass it could be, but was was mostly a test bench for the wing design
the heavier wing setup with FPV is another stepping stone toward a sub-250g 30+ minute flight time FPV wing.
The Twin was an interesting challenge to do something different... it was ridiculously stable in the air, but the landing gear needs to be redesigned if I keep it around.
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