Build instructions, as requested by Huey nut
Parts required in addition to your stock FP V2 Hummer and high C 3s lipos (Tp1320’s)
Aluminum tube 5mm (for the boom and subframe)
2mm carbon rod (for the skid springs)
2mm brass tube (for the skid legs)
Eco 8 flybar (for the mainshaft) or Drill Rod
Bag zip ties
Plastic Revell/ Monogram 1/24th HUEY kit
M24 Kyosho blades or Like90's
Aluminum gauze (car repair type) (used this for camouflage of the electrics)
Servo extension wires (to make Y harness)
Velcro strap (to attach the battery)
Original Hummingboard (as ESC and mixer)
(My current tail setup is a Feigao 4100kv DD tail motor and CC10, (it holds better)
This build is modular, meaning it can all be stripped down for maintenance and new components when required, or put back together as a real Hummingbird again (less a main shaft)
Build as follows:
Strip down and motor mounting
Firstly, remove the original tail boom, skids, RX, gyro, and motor from your Hummingbird leaving just the chassis, rotor and servos. Then modify (if required) the motor mounting hole, attach the 400DH, (fitted with an 8t pinion) and set the meshing. Remount the gyro in the chassis box parallel with the main shaft (I used a rate type gyro, a larger HH may require a little imagination).
Electrics (If you intend to go the Hummingboard route)
The CC25s connection to the 400DH is as normal, however the Hummingboard needs to be connected to the CC25 with a ‘Y’ harness, to trick it into mixing and powering the tail.
Basically the Rx throttle wire connects to both the CC25 and the Hummingboard’s main motor control wire, the CC25 retains all its RX wires but the Hummingboard loses its positive RC wire from the join. The Hummingboard is also connected to the Gyro for the tail motor, and this also has its positive RC connection disconnected. Doing this prevents the BEC’s on both boards conflicting and giving glitches.
Splice the Hummingboard’s ‘+’ and ‘-‘into the main power wires, with the CC25. I run a lipo alarm (HRPolyX) on mine too, and this is also spliced into the main power wire.
Connect the servos up as normal.
From the Huey kit, cut the left side of the fuselage in half, just behind the cabin end. I chose to follow the engine hatch line, and then stepped it backwards to give me some room to access the Rx.
Next, lightening the kit THIS IS IMPORTANT or the heli will be very heavy and affect performance; grind down, with a hobby drill and cutting wheel, as much of the plastic from fuselage insides as you dare. BUT it still needs to tough enough to be able to take abuse. I did the boom, cabin sides and roof, just use you imagination when grinding it out, think about strengths, weaknesses, and hard landings. And be careful not to go all the way through the shell when you doing it!
Chassis and Sub Frame
Hold the Hummingbird chassis inside the complete half of the Huey fuselage (with the main shaft lined up in the correct position, and the chassis high enough to carry the battery mounted under the new front sub frame to be). Cut two lengths of 5mm aluminum tube to make a front sub-frame, this will be used to hang the battery from, and to mount the ESC’s onto. Cut the two tubes to be just short of reaching the nose, when mounted along the bottom edges of the Hummingbird chassis. Mount the tubes using two nylon zip ties, I drilled a hole through the ‘radio box’ section of the chassis, and threaded one zip tie through. Then put one at the front, just before the motor but hooked behind the chassis skid mount points. You will need to narrow/squash down a little with a pair of pliers, one tube, where it runs under the ‘radio box’ section on the chassis, this is so it can clear the main gear wheel.
Zip tie mount (either now or later) the both ESC’s to the tops of both these tubes, and insert a Velcro strap in between them to carry the battery.
Tail and Boom
Again holding the chassis inside the fuselage, cut a tail boom from the aluminum tube to fit, and bend it at the end to follow the shape of the Huey’s tail.
To mount the DD (direct drive) tail (if you don’t already have one): ream out the old tail motor mount slightly, to accept the IPS motor’s shaft bearing, and drill through the end of the mount where the original boom runs into it. Attach the motor with heat sink, and put the tail box onto the boom ‘back to front’, so that the prop is on the other side to normal and the correct side for the Huey. Obviously swap the wires over and mount the prop in the correct orientation as to be a ‘puller’. Route the power wires for the tail motor, inside the boom as per the original Hummingbird (Go inside or you will get bad RF interference with the Rx being so close). The RX is mounted to the boom using a horizontal fin mount and servo tape, at the rear of the chassis.
The main shaft requires lengthening for several reasons, to be true to scale, to keep the fly bar from clipping the cabin, and not spoil the lines where heli meets the mast and head. The main shaft is made up from an ECO 8 fly bar, and uses its predrilled 2mm hole to hold on the Hummingbird rotor head. It also needs a second hole (which needs to be made) at the opposite end, which will hold the original head pin, this will keep the main gear wheel attached to the shaft.
Fabricated as follows:
Cut one end off the ECO 8 fly bar, to a length of about 11cm or so (basically high enough so that your fly bar doesn’t hit the cabin aerials or engine shroud when you hold the fuselage and the chassis together), the head end will be utilizing the pre-drilled ECO 8 2mm paddle mounting hole as mentioned earlier. Then (this is that hard bit) drill a hole quite close to the other end, big enough to take the Hummingbirds old head pin, and also roughen up the surrounding area with a cutting disc (this is to give a key for the glue we will be applying on assembly).
The original main shaft will need the gear wheel removing from it, so hold the shaft in a vise and twist the main gear off by hand, it will be tight on there but it does come off. Drill out the end of the removed main gear wheel, and drill a small pin sized hole across the bottom, to match up with the hole we just drilled in the end of the main shaft.
As the ECO 8 steel fly bar is softer than a normal hardened main shaft, temper the new main shaft. Use a blowlamp and a cup of water to temper it, just keep heating to cherry red and dumping it in the water repeatedly for about 45 minutes. After the shaft has been tempered and cleaned up, attach the main gear with epoxy and insert the pin. When it’s dry, insert the shaft and gear into chassis, and use the original shaft collar to hold it on.
To mount the rotor head on the shaft, drill a 2mm hole in the head just alongside the original pin hole, and fix it with a 2mm nut and bolt. (For looks, I also removed the swash plate from the plastic kit cut it down, and slid it over the shaft, before attaching the Hummingbird swash and head etc). The anti rotation arm will need extending, so using the original as a mounting point cut a small lump of ply to fit on top, and sink a length of piano wire into it, shaped as to be a new arm. Then screw and CA the new arm securely to the original anti rotation arm. Also from piano wire, cut some new servo pushrods to size, and fit them too.
You should now have a functional skeleton heli. I recommend that you put the Hummingbirds original legs back on at this point, program the CC25, wire the servos and gyro ESC’s etc up, strap on a lipo pack, and give it a spool. This is to see that everything is turning in the correct direction, and that the CC25 has the correct mode i.e. fixed mode not governor, startup mode set to (softest) and voltage cutout set to lowest, and the motor to run in reverse. When running with the Hummingboard mixing, stock blades and the shell attached, the heli seems to like a bit of revo mix, in addition to the Hummingboard mixing. But without the shell, i.e. as a pod and boom it doesn’t. If you intend to use a HH gyro and a brushless tail, it will be quite different and possibly different again if running with wooden blades, so a little trial and error will be needed.
The skeleton heli mounts inside the Huey body using its landing skid legs, which are made from 2mm brass tubes. The legs are fitted into the same Hummingbird chassis mount holes as the stock legs. However the skids and legs on the Huey are forward from where the chassis sits, so the skid legs must be fabricated in such a way as to bend backwards once they have entered the cabin, then curl up and round into the original mounting points.
The point where the legs enter the cabin is the second hard part of the build and involves a bit of lateral thinking. You need to determine the correct points to drill out the holes and slots in the Huey body, for the skid support legs to go through (holes in the complete half and slots in the cabin half). I cut a notch in the front skid slot, at the end (this helps ‘clip’ the body together when you fix the two halves together). Once the legs are made and bent to shape, the holes are cut in the Huey body and everything is assembled, it’s time for the carbon rods to be attached. They connect to each leg by a zip tie, and act as lifting supports for the body, plus springs for the skids. They are connected with zip ties, to the flat exterior part of the skid leg, under the body.
The skids themselves are made by removing the carbon rods from some old Hummingbird landing gear. Drill 2mm holes through the skids, where the brass skid legs need to go and slide the skids on. Push the skids up the leg a bit, and then bend the tubes over at 90 degrees at the ends at the desired length and trim. Then slide the skids back down the legs, and wedge the ‘bent over’ bits into the groove in the skid underside, this holds it tight. (Check the photo’s for a better understanding of the shape)
Join the body
All that’s left, except for making/painting the rest of the Huey kit, is to join the two halves (3 parts). Firstly the tail section covering the boom, this is just screwed and bolted through the tail fin (bolts CA’ed on). Then screwed into the side of a stuck on ply former, at the beginning of the boom. (Try and make these screws all seat as nicely as possible, as you will need to undo them, when you want to convert it back to a pod and boom heli.).
The cabin body is held together using dressmaking poppers, and the front skid leg in a notch as mentioned earlier. To mount the poppers cut 14 small 1cm blocks of ply, countersink and CA a popper ‘half’ to each one. When dry, connect them all together to make 7 connectors. These are then glued with CA and epoxy into the cabin join, while it’s assembled, and reinforced with more glue afterwards.
Once that’s done you can set up the RC and do a few flight tests. You will need to set up your TX up twice, one memory for the Hummer and another for the Huey, as they have very different flight characteristics.
Do a range check before flight, if the CC25 misses a frame from the RX glitching, it will cause the motor to splutter and the heli to drop.
When your happy with the flight its time to paint, spray and assemble the rest of the plastic kit, also hide/camouflage as much interior wires/RC gear as possible. For the internal camouflaging of the wires ESC’s etc, I used some car body repair aluminum gauze, painted matt black. The battery wire side door, is held on with a magnet from a governor,
Flying, the heli will happily fly scale speed circuits,and hover at 65% stick, however it is heavy at about 550 grams, and needs some respect when flying, as it can quickly gain quite a lot of momentum. (I suggest that flying the heli, with the Huey shell attached, be on visits to the gym and on very calm days only). Flight time is about 10 min runtime with the shell on, and the motors both run fairly warm along with the pack. Nothing runs 'too' hot.
Flight without the Huey shell... ballistic is probably the best word for it. With flight duration times ofabout 15min or so, both motors and pack run cool in this mode.
I’ve had loads of fun flying, building, and painting mine, plus the ‘wow’ factor when you turn up at an electric fly-in is amazing. Good luck if you plan to make one and I hope my guide helps you, and remember if you really hate it, you can always put it back together as a stock Hummer, all you’ll need is a new main shaft.
Warning...This hobby is very addictive and may damage your wealth