A return to model building and flying. Part 73
Leicester Model Aero Club
(Open) Control line Carrier Competition
It all went surprisingly well considering the weather forecast was for strong winds and rain. It did not look promising at all in the early morning with trees doing the usual thrashing about, although the clouds were letting the sun through.
flights in the morning were
enough to wake anyone up! but I did manage to get the Hellcat down on
the deck even if it then fell off the side. As the wind was so
turbulent I had decided to fly the Hellcat; I know it's traits very
which helps; it's also very stable at speed, also very heavy; just
means I don't get good slow scores, but stand a better chance of
completing a flight.
After a leisurely wind up in the morning with contestants doing a lot of fiddling. I don't think anyone appreciated that on our site we have to have a compulsory one hour quite period when no ic powered flights can take place, which meant that the leisurely wind up left us running an hour later than we should have been at the end of the day. I couldn't make up my mind if the mornings slowness was hoping the wind would drop or just unpreparedness, but after stuffing the barbecue down themselves, prepared by our hard working CD Andy Green, the enthusiasm seemed to get turned up a notch and indeed the wind did abate considerably as the afternoon wore on. I think everyone enjoyed themselves I certainly did, even managing two good landings which has restored a bit if confidence for the Nationals. We only flew Basic Carrier but there was more than enough excitement and organisation involved in the that event alone.
thing I 'must' now complete is
the spread sheet for carrier scores I have been working on. Working on
paper is OK, but doing it electronically has too many advantages to
ignore, like instant updating of positions, keeping track of pull
tests/noise tests/ entry fees and not having to calculate anything and
just typing in raw data. I don't know about anyone else but as the
day wears on and I get tired my brain turns to pudding, so anything
that takes away effort and brainwork is a blessing ( I do still soffer
with ME/CFS although it may not look like it, I just manage the
symptoms reasonably well ). As well as being
more accurate, hooked up to printer, everyone could go home with a
sheet as soon as we finish too.
Picture below is me and my
Hellcat on the day, all the messing about I have been doing with the
Irvine 40 finally paying off.
All the picks can be seen here and
will say far more than I can,
Please note: regarding
references to Motorvation Model Engines in the folowing piece, MME is
no longer in business and I do not know what the present situation is?
I am unable to answer any queries.
I have been cooped into evaluating a Sharma .19 diesel for Motorvation
Model Engines with a view to MME becoming
a dealer. For those that don't know, Sharma
are manufactured in India. As you can see this example bears a
superficial resemblance to the old PAW
design, but on closer inspection it is quite different. I am no
engineer, so I won't pretend to do an in depth breakdown of how it's
made or what it's made of. I don't even possess rev counter, and have
never needed one in all my years of flying. It's quirt easy to tell if
an engine is any good in a CL model, (1) does it start easily? (2) is
it easy to set? (3) is it consistent? (4) will it drag mode the model
you are trying to power with it around at the speed you want? The
last is the most subjective as a stunt model will have quite different
requirements for team race, speed, or combat. Just timing the laps with
a stop watch and keep changing props for comparison is one simple way
of telling if things are any good, I have enough experience to
tell if an engine has potential or is a dog just by using it. I tend
to get dizzy and desperately try not to fallover if a model ever gets
near or over the 160kph/100mph mark together with an arm that feels
like it's pulled out of joint, or end up doing a lot of swearing
backwards in a strong wind if it is underpowered ( all experiences that
flying an RC model can never give you LOL ). I am a very average flier
that likes to thrash something every now and again if I get the chance,
is where I am coming from and what you will get from me.
get ready for a good moan! Oh how I wish model engine
manufactures would use sensible units; the entire global automotive
industry uses cubic centimetres, but here we are apparently stuck in
the middle of the 20th century with model engines still using
cubic inches! I've lost track of the number of tv presenters that
state a distance in metres then in the next sentence quote yards, or
metres that suddenly become feet then back again, or temperatures that
seem to fluctuate between Celsius and Fahrenheit. It's
no wonder that people get confused. There was a time when you
could tell a diesel form a glow
because all diesels were in cubic centimetres and all glows in cubic
inches (although I must admit things did go a bit woolly with either
quoting each others units when over 2.5cc at one point in time. I
ought to thankful that that at least it's
decimalised, or we could be stuck with likes of a 21/100 or a 7/20th...
Doesn't quite have the same ring does it........! Strangely the Sharma
website does quote the diesel sizes in cc and the glows in ci thus
maintaining the old tradition, so why is this diesel stamped in ci? I'm
still waiting for the first manufacturer or marketing idiot to call a
diesel a Nitro engine.....!
Anyway, enough of my drivel.
John Walton of MME being ever the
perfectionist, was not too enamoured with the finish on
the engine, which apart from a few dints on the fins looked fine to me.
So it was duly squeezed into my my now old Hallam Swift You will have
to forgive the tatty front end of the model, its had many engine
changes and is on it's second nose section, plus the fact that
Solarfilm is not known for it's diesel fuel resistant qualities...!!.
One thing I can say is that it has one the best piston liner fits I have experienced for a long time on a new engine. This undoubtedly gave it the very easy starting characteristics I experienced, bordering on a lazy flick more akin to hand starting a glow engine. Another thing that came as a pleasant surprise was the lack of vibration, I am used to engines of this size being a bit rough running with sometimes unpredictable in starting.
Flight testing was uneventful with the engine running at a steady rich misfire to avoid it over heating for the the first few runs. Because the compression and needle settings were so soft, by that I mean not critical, it was easy to get consistent runs what ever you set things at. The next days flying was cranked up a bit with a just breaking two stroke. Again no problems what so ever, except for one mysterious moment when it refused to start and would only respond to an exhaust prime. This turned out to be the needle being a lot more open than it should have been and flooding the engine. Restoring it to it 's original position gave a near instant start again. The needle restraining spring needs a little tensioning.
of other things of note, the
crankshaft is not threaded but hollow to accept a prop retaining bolt,
not a new idea, but a very practical one, and the large compression and
locking lever is very easy to use if you wear gloves, (which I always
do for hand starting and they are reasonably thick leather), so that
lever is a boon; as it would also be if you had to start the engine in
was beginning to warm to this
engine, I will be a bit reluctant let it go at the end of testing.
Having got rid of a new PAW 19 some time ago because of
it's very unpredictable starting and debatable performance (whether I
just had a bad one I can't say as I only had the one to judge by), but
this engine was
like chalk and cheese. I have no idea what I can get out of it yet, as
it it is still running in, and I had no muffler because none is
available, so I was pushing things by attempting to flying it at my
club anyway because of the noise regulations.
I have a strong suspicion that the lack of an available muffler has been the main reason I have never seen any of these engines about. It's nice to have open ported engines revving away, if nothing else they are easier to tune when you can hear what's going one, and any engine will be somewhat restricted in performance when you put on a muffler (strangler would be a better term); but if you have nowhere to fly them, or get thrown out of your club because of it, I know I would sooner put of with a loss of performance and still be able to fly; it's that simple: a case of put up, or shut up!.
In this day and age it is
have some form of quietening supplied with an engine, it can always be
removed or modified
by the owner post purchase. But not having one, or being able to easily
hold of one, is a recipe for customers ( that includes me ) thinking
twice before handing over cash.
So after after the initial testing, with
a bit of nudging and none too subtle hints from yours truly, J.W.
produced a workable prototype muffler for me to test. The design should
should also make it possible to fit it to other older radially ported
engines that never had one in the first
place, something that has been lacking
on the market for a very long time. Although if they employ sub port
induction all bets are off performance wise. PAW do make two types of
silencer, but the
standard one they supply with an expansion chamber makes the
incredibly difficult to start for newbies. I suspect it has put more
people off than encouraged. That size of engine becomes much more
manageable when they are removed; but then you end up in a catch 22
situation if your club insists on silenced engines. The simple ring
collector muffler works better, or should I say is more practical after
a bit of sensible tweaking, but is too flimsy to fit other makes of
levelled up the bearers to a less stressful angle and also cleaned up
which was a little poorly finished, and it has to be said that some
internal parts are a little crude to say the least. But I have a
pragmatic approach to low priced engines, I don't care what the engine
looks like as long as it
runs, runs consistently, and bits don't fall off. In this instance the
bits that matter do
seem to work properly. I have no way of knowing if this less than
optimal finishing is standard, or if new ones any better. We may find
the months to come? So all I can do is comment on the one I have loaned
to me and not surmise about something I have no knowledge of.
A couple of days later I had the
chance to test the muffler. I can report that it made only a very
slight difference to starting, for me that amounts to not being easy to
exhaust prime with a side mounted engine. One solution would be to have
small hole in the collector ring on the opposite side of the engine,
but I suspect for most people an inlet prime would suffice, as indeed
did for me once I had found the right settings. As previously when
starting without a
silencer and from cold, it still seems to need the needle open half a
and the compression turned up a quarter of a turn from the running
positions to get easy starts; nothing unusual there then. Hot starts
are a doddle, just flick and
There is marked reduction in noise
when flying, but I didn't notice
all that much difference in performance. This could be down the the
that I am using a 9x6 prop which is obviously on the large
size and holding down the revs. All I can say at this stage is that In
a model the size of the Hallam Swift I could quite easily go through
the stunt schedule without the model racing away with me (given a
little practice). In a slightly larger model I suspect vintage stunt
events would be do-able, and some of the larger vintage FF models would
be well suited too. I have yet to test smaller props and go for higher
revs, but with the UK Nat's looming large,and the engine is still
running in, I am in no hurry to try right now. I'm just glad I can
continue testing it now at my club site.
regard to running in I have experienced no signs of a sudden reduction
compression, something that sometimes happen with poorly machined
piston liner fits, and can't see any perceptible scoring on the
piston surface after what must amount to five large tankfuls
through in flight, even with the occasional accidental over compressed
grind to a halt.
These engines are obviously build down to a price, so don't expect major manufacturers standards in finish or performance if you ever buy one. But they look like they could be an ideal power plant for sport flying, or tuning and experimenting with, I can imagine them suiting a whole range of vintage models. So providing a batch of other engines and sizes are a similar quality (or better) they will make very usable sport diesels in the 1.5, 2.5, 3.2 range, (.09, .15 and .19 if you must) and Coupled with J.W's silencers this will make a bit of killer combination, and even more so if the rc throttles work too. J.W. is already hintng at coupling a throttle to a variable restrictor in the muffler to try and keep up the head temperature when throttled down, an interesting concept. I'm impressed enough to already have an order in for a pain venturi 1.5. I am sure J.W. will not let any of these engines off his premises (assuming the deal does goes through) without all the minor niggles being fixed first; and probably run them too, just to make sure :-D
conclusion: a bit
finished inside and out, but the bits that matter are well thought out
and working, at least on this example. So you pays your money and you
takes the risk if you buy
one today. If Motorvation Model Engines gets the dealership, you can
expect something that may cost a
little more, but will be a little less likely to spring any nasty
I have no idea what the prices will be like, I want to know myself? So watch this space.
Knocking your own countries products?
I haven't had time to write anything about another abysmal UK Nationals weather wise. I'm actually at the point of wondering if it's worth writing anything at all? But one thing did strike me during a conversation with a non British Citizen whilst there, when I asked what lines he was using and mentioning that we had seen a few failures of this type of line. The reply was to the effect that they had never had any problems and that we British have a habit of knocking our own products.
I would be the last one to
dispute this, but unless you live here for a considerable length of
time and have first hand experience
of a lot of shoddy goods over the years right up to the present day,
this is not quite the whole story. The phrase, 'Rip Off Britain' didn't
just appear out of thin air for no reason, the only reason it's
not so prevalent these days is because we hardly manufacture anything!
If things are good or even
reasonable I will say so, if they are bad or there is a worry, I will
say so too; only louder!
this instance I have seen lines
fail and in a very worrying manner. They were stranded tinned steel
bought as a bulk reel for making up lines. A new set of lines had
failed a pull test, and upon closer examination the failure had
occurred on black patches in the middle of the lines. Obviously this
was corrosion, either happened before tinning, or the tinning
was not thorough. Either way this was no joke, as a whole bulk role is
now suspect. On talking to others it appears not to be an isolated
incident. As these lines all come from one supplier it does make you
start to question things.
This is not restricted to lines made in Britain. Again I have seen crimped stainless steel lines give way or slip at the crimp on more than one occasion ( let alone things like the lines being wildly different lengths if they are made up ones from companies that you would think would care more? ). Let me state categorically that there is nothing wrong with crimping. Let me also state emphatically that this only holds true if the crimping is done properly. The latter implies strict quality control and testing. which I doubt goes on with the likes of made up control lines. And how often have you seen lines made up at the field with a pair of pliers or worst still cutters employed to produce the crimps? I have, and more than once.
All this is one reason I don't use crimps on stainless lines. I bind and use adhesive. I have even pull tested samples using weights with no adhesive to see how good they are, so I know that I have some latitude for error after applying the adhesive. Binding can also be used to spread the stress so that there is no sudden change as there is in the last crimp. Obviously this is not possible for producing lines as a business, for time reasons alone, so crimps are used along with all the attendant ways of failing.
as you can see this is not
simply knocking my own country's products but born out of a genuine
concern about safety, and also not wanting to loose the hard work that
goes into building models. So please check your new lines visually and
carefully before even getting near a pull test, and then make
sure you get someone to help you give them a good pull
before that first flight. It could save a lot of embarrassment, money,
and someone's good health. We don't have many accidents with CL., it
must be be one of the safest forms of powered modelling around, but
what we rely on; so treat them with great respect and don't rely on the
manufacturer to get it right all the time.