Ripmax Sirius Electric

Tim Brocklehurst, 29 Jan 2004

Why ARTF?

It's the middle of winter, in the middle of Southampton, and in the inter-semester break (read exams, lots of nasty ones). With some cash, no time, no building facilities, but a pile of old radio gear ripped from my old 6ft tailless model, I decided that It was time to see what I could do.

The problem was - I didn't have a big hill to fly off (and certainly, no way of getting to one). I had always been interested in electrics, but I'd never had the need to build one, so there I was, I had a need, and it seemed like a good idea.

I have always enjoyed looking in model shops, there are so many disciplines that come together in one place. Art, Electronics, Engineering, Science etc. I had been told about the Sirius by a friend of mine, and so I asked to have a look inside its box.

Box Contents

The first thing was the plastic blow-moulded fuselage, ugh, I hate them (I'll give it its due later)! It was supplied with a 600 size electric motor already fitted, along with the radio tray.

The wing is two-piece on the Sirius, and the only bad thing about it was the tiny wing joiners supplied in the kit - longer ones would have been nice. The general construction of the wing is impeccable, though the covering on mine left a little to be desired - a hot iron and all was well. The servo extension leads were already run through to the servo bays.

The tailplane is a T-tail. The tailplane and elevator were pre-built and pre-covered, but the elevator was a bit warped (again, the iron was used, and all was well).


The box with Field Force 6 Transmitter.

Building

Thus far, I have not seemed impressed, but I can assure you that it starts to get better, because nobody can mess up the building if they use the instructions and some common sense.

I'm not going to elaborate on the instructions, other than to say that a piece of triangular stock should be glued between tailplane and fin, on each side, and obviously (the surrounding covering film should be cleared first).

Also, take care with the control horns and take your time. The aft wing-mount also doubles as a control guide. A spot of cyano on the tube helps stop the elevator control rod moving. Also, some larger heat-shrink tubing on either side of the wing-servo connections will stop the cable from unzipping.

Departures from the Instructions

For the elevator servo, I just bent a Z in the pushrod rather than using the supplied connector which I broke trying to fit.

The speed controller, was a NON-BEC homebuilt job which then meant I needed receiver batteries (the really small ones from Ripmax). The other free-moving gear (flight pack, receiver etc.), was all held to the radio-plate (already built in) with rubber bands (nb. There is nothing in the instructions about that).

A fuse was built into my speed controller power line next to the motor as a safety feature.

Hitec HS-80mg servos were used in the wing because they were all I had, though the suggested SD200s would be more than adequate. In fact, I have used SD200s on many slope aerobatic models and never had a problem. With this setup the C.G. was perfect. I started on six-cells at 2000mah, then 7 cells at 1700mah, and finally 7 cells at 2000mah. The batteries all balance the aircraft on the C.G.


Cosy, but not too tight for the HS-80s in the servo bay.

Flying

First flights were hand-launches to check the setup. Without power it was apparent that there was an aileron warp, but with a little trim, it was flying very nicely hands off.

It is worth noting, that there is quite a bit of dihedral on this model, so it will fly 'hands off' without much fuss.

Anyway, on full power and six cells, with an easy launch, and Sirius didn't climb away. oh, up elevator, that's it. The Sirius now climbed respectably, and a few climbing circuits were done. Having assessed the climb, and general flight, I tried a landing. It stalled, dropped a wing and took the tailplane (and thanks to the reinforcement, part of the fin) off completely. Anyway, some 1/64 inch ply and some cyano later, the Sirius was recovered with some silver solarfilm and was flying once more. The fuselage was fine.

In the following flights I really got more used to it, and tried flap mixing, and elevator flap mixing. It's useful, but quite sensitive.

For landing the instruction manual suggests "fly the model downwind 30~50 mtrs at about the height of a house and turn it towards you into wind. Slowly close the throttle and let the Sirius start to descend." a suitable amendment might be "when flying in a small area (such as Southampton common), attain a little more than tree height, then close the throttle, turn into wind, and do S-turns for about a kilometre to lose height!!" though this was taken from the standard flying instructions page. This model glides remarkably well, and from what I've seen, much better than Ripmax give it credit for. The little part of Southampton common that we usually fly on being surrounded by trees and about a kilometre long by 400m wide, provides adequate space, especially if it is calm, or there is some breeze down the patch.

Summary

Apart from the blow-moulded fuselage, the T-Tail and the short wing joiners, it is very nice. However, I actually have no basis for saying that any of these things are really that bad. The blow-moulded fuselage does seem very tough indeed, the T-tail is there to get the tailplane and elevator out of the prop-wash, and the wing joiners haven't pulled out of the wing (but I have been gentle with it). As in all these models, there are things I would have designed differently, but all in all I'm very impressed.

The Sirius is a very nice model, and I would certainly recommend it to most modellers as a way into electric flight. The Sirius could have a rudder added quite easily, though it is not strictly necessary, there is space inside for the servo I wouldn't say it was suited to an absolute beginner, but for someone who has mastered the basics, it is a nice model.

Be careful if you're flying slowly, because it does drop a wing, but overall it is very well behaved. I'm currently using a Field Force 6 transmitter, and making use of the aileron wing servos/flap mixing/elevator flap mixing functions, but they are not altogether necessary. It could be flown easily on the likes of a Skysport 4, or even the three-channel radios that are around. Nice one, Ripmax.

From RIPMAX From Experience
High performance ARTF model electric glider Higher performance than many
Tough blow moulded fuselage with built up wing and tail surfaces finished in transparent & white film Generally, nice construction, fuselage certainly seems tough
Full colour decal sheet Yes, those too.
Comprehensive illustrated instructions Ok, but seek advice for first flights
Full set of control hardware including pushrods, horns, clevises etc All hardware (not radio/servos/speed controller obviously)
Pre-installed powerful 600 size motor and propeller assembly Fitted prop seems to be optimum, though the fitted motor could be improved

It was the middle of winter...


... on our little flying site.

Specs

Model Sirius
Span 63 inch span Electric Model
Manufacturer Ripmax
R/C

3 to 5 channels (dependant on flaps and rudder)

Weight 1.1 kg
Price 89.99 (kit)
340 (inc. radio and batteries.)