Report on the Hirobo Sceadu 30 by Bob Johnston
The Sceadu has been around for a few months now and although it has sold in reasonable numbers it has not even come close to touching Raptor sales for us and I suspect the UK market in general, this might change when it finally filters out how good it really is!
I have to confess I didn't really have time to build the model so "volunteered" Danny to do this, the first signs of what sort of model it might be was when he built it in a couple of evenings and said it was the easiest model he had ever had the pleasure of building! The model is fitted with one of the new Irvine 39 Heli engines and although the kit is supplied with a muffler this is a cheap sort of standard muffler which I do not think would allow the best performance out of the engine, I am sure it would be fine for a novice or sports type flying.
We fitted a Hatori #350 3D pipe and matching header as this
seemed about the best choice, and the separate pipe and header would allow some
tuning of the engine speed via lengthening or shortening the pipe if needed.
Radio used was all JR other than the gyro, DS811 servos on the collective and
cyclic, a 591 on the throttle, and a DS8455 on the tail to match the CSM 540
gyro; we used a JR 649S PCM receiver and a JR 1100ma NiCad pack.
I was a little concerned that the model might have over
heating problems as the models built in cooling duct comes a long way short of
actually covering the engines cylinder head, but I have not had any over heating
problems with the model, I have not flown the model on a really stinking hot
humid day but certainly a average English summers day does not give any
indication of problems.
First flights were extremely promising but mard by a
persistent tracking problem, I tried a number of different blades and even
flipped the blade grips over so the pitch arm was on the leading edge, I
stripped down the blade grips and checked all the bearings, everything was ok
and the thrust bearings were greased but still the problem persisted! I
stripped down the grips again and cleaned off the grease from the thrust
bearings, gave them a very through check and regreased them, at the same time I
greased the damper rubbers lightly as these were a tight
fit, this has cured 99.9% off the tracking problems; I tend
to think greasing the dampers was the cure rather than anything to do with the
thrust bearings. To be fair the instructions do show a little oil symbol
indicating that you should oil the spindle, I think Danny missed this, it is a
very small symbol so an easy mistake to make.
To go into a little more detail on the tracking problem,
this manifests itself as the blades suddenly going a long way out of track
(maybe as much as 5cm) and then jumping back into perfect track a second later,
this is normally caused by bad thrust or radial bearings or blades with too
rearward chord wise CofG for the rpm you are trying to run, but in this case all
of the above has been checked and is not the cause! The tracking problem
is in some ways rpm related and only happens at a high head speed, I would
estimate at about 2000 on the rotor head (my Tacho is still not fixed) so should
not be a issue for most but if you must set the model up for it's maximum 3D
potential with a engine like the Irvine 39 you probably are going to get close
to this rpm. In any case the tracking problem is not really a major
problem since greasing the dampers and only happens very occasionally for a
split second, in most cases you can't even see the blades go out of track but
just hear them, I have started to ignore it and just fly the model.
I have to say I have been very impressed with the way the
model flies, it is easily the best flying 30 model I have flown yet and I've
flown most! The one thing that probably does more that anything else to
make the model feel so nice is the tail rotor, the Shuttle has always had a poor
tail rotor due to a poorly designed sloppy tail pushrod and a
equally poor tail pitch linkage, well Hirobo finally did
something about it and the Sceadu has a really good pushrod and linkage as
standard, the rear mounted servo probably helps a little to, for any type of
aerobatic flying it is really important to have a controllable predicable tail
rotor and the Sceadu tail is certainly very very good.
The only differences between the 30 and 50 versions of the
model are the engine mount and gearing, dimensional the models are the same,
this means you can fit up to 60cm blades on the 30 version, most 30 engines will
struggle with this size blade but it does give you the option of fitting longer
blades specifically to learn auto's and certainly the model auto's fantastically
with this size of blades so I think it would be well worth the expense of buying
a set of good 60cm blades if you wanted to learn auto's on this model, it
certainly makes it THE BEST autoing 30 model.
I have ended up using 58cm NHP Razor's on the model, I
tried 55cm blades but the Irvine 39 has heaps of power and has no problems
swinging the longer blades and they certainly improve the auto's a lot, 60cm
blades load the engine just a little too much for extreme 3D stuff. The
cyclic rate is just about right for me; it's about the same as the Raptor 30, if
you want it faster than this then just fit lighter paddles like the K&S
ones.
I have been very impressed with the new Irvine 39 engine,
it is very difficult to say just how powerful it is with out continually
swapping different engines in the same model to get a better feel for which has
the most power but I am certain it has at least as much power as the previous
most powerful 30 sized engine and maybe a little more, it also runs quite
smoothly. The quality seems good to so what more could you want from an engine!
It was not many years ago when even the highest spec 30
models needed at least a few upgrades to make them accurate 3D models, the only
thing none standard on our Sceadu is the NHP main blades, so far I have about 25
to 30 flights on the model and everything seems good so far, only with long term
abuse will we find out if the model will need any upgrades due to wear but I
can't see many being needed.
The funny thing is the model is so good you find yourself
looking for little faults in it's flight performance, I found the tail starts to
whip a lot in rippers but then I had to remind myself that it is a out of the
box 30 model not a top of the range 60 model! It has no problem with just
about any other 3D manoeuvre, including pirouetting loops, rolls, chaos, etc. To
pick fault I would have to get niggly and go for minor things like the canopy
mounting is unnecessarily fiddly and I don't like the green decals as they do
nothing to make the model easy to see at a distance, though I like the over
style of the canopy.
So summing up I would have to say it is my favourite 30
model, the 50 version should be good too, generally I have not been a big fan of
Hirobo designs so it came as a pleasant surprise to find what a great model it
is, good job Hirobo!