Acemodel’s Electric Mamba Review

A fellow modeller, Austin Miller, spotted this on the Acemodel web site and asked me if I would put one together for him as he is more into flying than building. This is a bit of a misnomer in that it is more assembly than construction. I picked up the Mamba with another model that had been ordered, and was surprised in how little there was to the model. It consisted of right and left hand wing panels, a stubby fuselage complete with a bag of accessories comprising of wing joiner, motor mounting plate, wing retaining screws and covers for the servo hatches in the wings. First impression was the colour would not be ideal for viewing in flight, being Light Blue with contrasting Dark Blue panels underneath. As it turned out, it did not vanish into the background of the sky, but stood out surprisingly well!

I gathered together the parts needed to complete the model, namely a power source in the shape of a Mega 22/20/3E In Runner, 60 amp Speed Controller (Hi Model), 10x6 folding prop, 38mm dia spinner, two Ripmax SD150 servo’s, brass horns for the elevons and finally a Tornado 3300 3 cell LiPo.

First job was to fit the brass horns into the elevons. These should be fixed with plenty of epoxy around the horn inside the elevons to give good support. This is important as they will be exposed to close proximity to the ground when landing.
Next the servos are fitted into the wing after checking neutrals and correct direction of throws. I use epoxy to glue them in place after fitting heat shrink tubing over the servos and removing the servo arms. I partly shrink the tubing, and then cut a small hole around the splined shaft for the output arm. Next shrink the tubing fully to fit around the servo, rough up the side to be glued to the inside top surface of the wings. Refit the servo arms and make up the push rods for both servos with clevises, and attach to the servo and elevon horns. Finally align the servo’s squarely to the control horns and when satisfied glue them in position.

You will need two servo lead extensions to connect the wing servos to the receiver. These pass through the two holes in the wings that are positioned over the fuselage access where the wing fits when screwed down. These need to be long enough to plug into the receiver with the wing clear of the fuselage, and enough hand clearance to gain access to the plug sockets in the receiver. There is plenty of room for the leads to fit inside the fuselage. Tape these up where they attach to servo the leads so they do not disconnect inadvertently.

Drill the motor plate to take your motor of choice, and then glue it into the nose on the inside hard against the front reinforcement. I groove the inside a little way back from the front. This provides support against the motor being shunted backwards by the epoxy glue settling into these recesses.

Apply some Velcro onto the inside of the fuselage behind the motor to hold the battery. Likewise another piece of Velcro to attach the Rx. Use the same method to attach the ESC on opposite sides. (See the photograph for help)

Place the flight battery inside the fuselage and assemble the model to check out the CG so that it balances where indicated in the instructions. This is quite a narrow band of 5mm tolerance. Move the battery forward or back to achieve the desired position. Set up control throws as stated on the enclosed data sheet.

Flying

This is always the good part. As it was Austin’s model, he had the first flight and I was very taken by it. The speed was very impressive, as was the models ability to soar in light air and thermal away. Indeed when I flew it on a subsequent flight, I was orbiting with a Kestrel in a thermal. At times it was hard to distinguish the kestrel from the Mamba, as it does have a very bird like plan form in the air.
Loops, rolls (which are faster to the right than left, due I suspect to inertia of the electric motor) inverted flight, even stall turns are all possible even thought there is no rudder control. Landing is quite fast, due to the weight of the model with the large LiPo that was used.

As yet we have not tried moving the CG back, but this may aid the landing a bit as the model is very benign and easy to fly. Indeed it seems virtually impossible to stall with no tip-stalling tendency that I can detect.

I think that the addition of separate elevators, in addition to ailerons or elevons as used, would produce a better overall control response, as when the model is rolled you cannot use down elevator to keep the roll axial in longitudinal axis as this takes away some of the aileron throw. It may also be possible to have some crow breaking programmed in to aid the landing. A bit of a bind having to remove the wing to get to the battery connections, this could be overcome by having one of the battery connectors exiting the fuselage side underneath the wing, this would allow you to connect or disconnect without removal.

All in all a good buy.  A good model to have in your inventory, as it will fly in strong winds, even take the prop off and fly as a slope soarer. Another benefit, it takes up little space in the car.

Brian Austin.

Austin Miller with his new Mamba Electric