subarubrat

My Feedback: (1)

My first heli back in the mid 80's was an American Helicopters Super Mantis. It weighed about 7lb flight ready and flew on a .40 class sport engine, regular 4ch system and a gyro was optional. It was about the only way an 80's teen could approach the heli market. They didn't fly well and were a very early design for sure but I really like this machine. I have built up a stockpile of kits and good condition built ones and think it is time to put one in the air. With today's stabilization gadgets you can fly a brick so I would like to convert one I just bought so I can have a nice flying example. The model was not under powered with a sport .40 glow, extra power on tap would be nice but I have no intention of doing more than docile sport flying. I would also like to skip the belt drive system for the tail rotor which was the machine's weak spot and just go to a direct drive tail rotor/motor. I just don't know where to start with selecting main rotor motor and pinion and the t/r motor prop, with the right ESCs, and equally lost on pack selection. What I can do is create and share a 3D STL model to adapt the motors to the air frame and mount batteries. I would guess other owners might actually want to fly one.

SPECS site: https://www.vrhc.co.uk/index.php/en/mantis

BarracudaHockey

My Feedback: (11)

Following....

Cool project, I had a Revolution. When I got a Concept 30 I said I went from a helicopter owner, to a helicopter pilot.

subarubrat

My Feedback: (1)

This is the subject. I got it with two minty K&B 40s and some vintage radio gear for right around 200. The heli has no damage or corrosion, it looks like the engine was started enough to spin the rotor up and it probably was an ornament after that. I tore it down last night and other than some gritty open race bearings and a few semi stripped screws I have a table with a minty fresh dissected Super Mantis. I feel like I have enough spares and untouched originals on hand that I want to risk actually flying one. And contributing as well, now that I can just print any of those plastic/wood parts, even the canopy itself there isn't much you can't replace if damage happens. My original one never did more than spastic bunny hops, but this is one of those inspiring designs full of contradictions that you just want to work. I can't say I have ever really flown one but it has been a personal favorite since I saw the box at the LHS containing a helicopter I could afford without a gyro and I could reuse my trainer .40 and 4ch system, all from the teenage income of hooking up illegal cable for your friends, which was ok because it was the 80s.

I really want to make this thing fly with as much stability and reliability as possible and I know it is certainly possible with the current state of things, maybe not off the shelf, but I am willing to put some effort into this. And much like BarracudaHockey there, when I got my LMH110 I went from owner to pilot and the LMH has remained a favorite but Ive always wanted to make the design work the way I had hoped it would.

subarubrat

My Feedback: (1)

The heli is ready for reassembly, the bearings are some rare sizes so I picked a new set from an unbuilt kit, flushed and regreased them. I don't know what the tail belt is made from but all the ones I have are as good as new and certainly made of something the EPA banned in 1983 so I am going to try belt driven to stay as OEM as I can. It has knurled spools for the belt and the updated aluminum pulley on the main shaft so it might work. After allot of digging I found a software/hardware project called Rotorflight that works on a number of flight controllers. I chose the Heli 405 and by all basic specs it is built for what 99.9999etc of the world is flying, and of course it will be flown upside down all the time. I am the .001 share of the market that wants to make a whirling mess fly like a quadcopter. There is a little documented mode in Rotorflight called Direct that lets it control an old fashioned two servo swash plate configuration, according to various posts on the internet.

The last major selection is the motor ESC combo. The practical electic heli era came so far after this model's prime that none of the published info is useful. The best I can figure is that the heli flew on a trainer grade .40 two stroke glow with OK power so shoot for a setup close to that and adding a little overage would be an ok start. The best charts I found put that figure right around 800 - 1000 watts. The other concern is the driveline. There is no one-way bearing, the clutch would have been the mechanism that would have decoupled the engine from the gears and allowed for autorotation. I could literally put the electric into play by bolting on the clutch using a prop adapter, which would be super easy for allot of reasons it would also allow for the rotors to freewheel in the unlikely event of a motor failure. Or I could just do pinion to main gear and probably nothing would ever happen. I can't think of a meaningful downside to just keeping the clutch other than a minor wear item that is dead weight, if you have a thought on it please give me your angle. The electric conversion is looking like I will end up with a very comparable takeoff weight to the glow configuration.

Other than struggling with a color and graphics scheme I have only the motor and ESC to finalize selection of before assembling it.