BLENHEIM MAC PROPWASH AUG/Septr 2011
President Tony Rogers firstname.lastname@example.org
Sec/Treas Murray Herd email@example.com
Editor: Guy Marfell firstname.lastname@example.org
Contributing editor: Rex Ashwell email@example.com
club website: http://www.bmac.org.nz/index.htm
Blenheim MAC and all its flying members are affiliated to the national governing body, Model Flying NZ.
Editorial: Regular readers will notice that this is another “bimonthly issue”. There are a couple of reasons for
this. Firstly there has not been big Sunday attendances to report on, indeed midweek turnouts have been larger.
Secondly compilation of this bulletin takes much personal time and effort. As always I solicit your pics of models
and projects with a few details to include here. Digital cameras and email makes it so easy for you to do. This
request is not limited just to our small membership, but the wider aeromodelling community. Marf.
Subscriptions Unfinancial and intending members please read the previous Propwash.
Fuel Supplies Secretary Murray has got supplies of fuel It will be cheaper than getting it direct
yourself due to freight savings. Byron (USA) AeroGen2 10% nitro is now in stock which suits both 2 and
4 strokes. Murray usually has stocks with him on Sundays.
Lake Forsyth Float & Field 27-28 August. Directions www.radiofliers.org.nz
Glider Tow Day. Saturday 3 September at Blenheim MAC ARA site.
This follows a request by Peter Deacon for a day that can be participated in by both BMAC and MAMS
members. The only proviso is to be a current financial member of your club/s (therefore third party
insurance). A Saturday has been chosen so that both clubs can have their normal club Sundays without
impediment. As this is an inaugural event participation may not be high, but if you are interested please
come out and see how it is done. You may want to try it. Peter has re-engined his Pawnee with a petrol
DLE 20cc and fitted a well enginered tow release. This will be available to tow up any suitable glider
fitted with its own release. There may be also a second petrol powered tug for tow duties. The intention
is to drum up enough support for regular tow days. Other model types my be flown, but towing will take
Float-Fly Report, Lake Pinot, ARA vineyard Sunday 31 July.
Blenheim MAC is blessed with the most perfect lake for float flying on the same property as our runways. ARA
the vineyard owner is very happy for us to use the lake as long as we comply with their rules and those required
by OSH. A couple of days before the event your secretary and scribe met with ARA management and “fleshed
out” all the requirements over coffee at the Dart HQ. Arrangements to insert our own combination padlock at the
main gate worked OK, and maps were provided to supplement the email. As far as I know this prevented a
repeat of those who got lost in previous years. I got one complaint that the cell phone number provided at the
gate did not work, and thus some visitors could not get the combo number and gain entrance. Apologies for that,
and we will check out cell phone reception next year. Even though we had a blackboard and maps at the
maingate we heard that someone attempted to get through the side gate. We will label this as “wrong gate” next
year. We had fliers from Nelson, MAMS and Christchurch all taking advantage of the most perfect conditions. It
was a joy to see several models airborne at a time. Thanks must go to Peter Deacon's two boys for operating the
2 retrieval boats,and those who assisted secretary Murray in various ways. The sausage sizzle provided a modest
profit and so the decision not to charge a registration fee was well founded. The continuous free hot drinks was a
boon in the early frosty conditions. It was a great day, see the photo gallery pics. Marf.
Safety comes first! Your scribe has been accutely aware of propeller chomping since being a “recipient” and
witnessing an accident in recent months. Everyone should remove the razor sharp moulding flash off composite
props before use by sandinding or scraping, then follow fullsize aviation practice by painting the prop tips. This
can be done in a few seconds using a small paintbrush and applying paint freehand. Yellow or white seem to be
the most effective colours.
The club trainer The secretary is the custodian of the club trainer. This is an electric powered 40 size highwing
trainer. Intending members unsure of whether R/C flying is really for them may take a trial flight. Murray will
usually have the model available on Sunday mornings weather permitting. Please make this service known to
anyone expressing a genuine interest in taking up R/C. The club allows a short period before requiring new
members to sign up and pay the subscription. This is to save any outlay and then deciding against the hobby.
Spark plugs While there has been the 2.4 GHz and electric revolutions going on (well covered in Propwash),
there has also been a petrol power revolution going on. This has been due in no small way to the excellent small
Chinese gas engines now on the market in sizes from 15cc (90 cu in) upwards. Unfortunately there has been lots
of grumbles in the forums that the plugs supplied with these motors are not up to scratch. Many of these plugs
are the 10mm size and styled after the excellent NGK CM6. Consequently it has been common to replace the
original plug with a CM6. This plug is not easily obtained in NZ, and one local supplier is quite expensive. Well
Toyota NZ are agents for the Japanese Denso brand and what's more they stocks the NGK CM6 equivalent:
Denso U20MU. I have obtained one and test flown it on an RCGF 15cc engine. I set the gap to the same as the
original plug (.020” /.5mm) and detected slightly better take-off power. And here's the best bit, price about NZ$4
from your local Toyota dealer! My 2 Chinese petrol engines came with very little in the way of instructions,
certainly no plug gap info so I first checked the gaps and found them to be around .060” , then used them as is.
With a bit of Googling it seems that a typical recommended gap for a 10mm plug is .017”/.44mm. So why were
my engines supplied with .060” gaps? Did it matter anyway? Well I have ground run my engines on both big and
small gaps and could detect no differences. In the end I have settled for .020”. My conclusion is that the CDI
ignition units these engines use are so powerful that plug gap is not critical. Marf.
Spark/petrol conversions It is quite practical to convert model glow engines, both 2 and 4 stroke to spark
ignition and run them on petrol. Though the power is slightly less than running on glow, a very reliable idle and
good throttling is gained, and fuel costs much reduced. Astute observers at our float-fly will have noticed that Raz
was running a spark conversion in his float plane. It ran very steadily. Check out the conversion kits available at
Hi model. A suitable 1/4” X 32 TPI spark plug (same thread size as a glow plug) is available separately.
Repowering battery electric drills Battery drills are great, but unless you have an expensive one with A123
style cells (lithium ion nanophosphate!), the time will come when the old nicads will need replacing. If you are like
me you just cannot retire the drill and eventually throw it away. Here's what you do; open up the battery case and
remove the old nicads. Measure up the battery space and consult the Hobby King catalogue for a Lipo battery
that will fit. In my case a 3S gave a voltage very close to the original rated 12V, and 1800 mAH gave ample
capacity. Next you need to solder a positive and negative wire to the battery case contacts and fit a suitable plug
to mate with the new Lipo.
As I did not want to open up the battery case every time for charging I made a hole in the case for the balance
plug to protude from, and I charge via this plug. There is no protection against over discharging so it is up to the
user to recharge when the first signs of slowing down are noticed. You could connect a voltmeter to the balance
plug and measure the voltage occasionally. In practice this is not a problem, the performance is far superior, and
unlike nicads there is no annoying self-discharge. Do not use the old charger that came with the drill, use your
model Lipo charger, and always stay in attendance whilst charging is in progress. So far 3 members have
converted their battery drills in a similar fashion with great success. Marf.
Pics: top left, paint your propeller tips.
top right, battery drill Lipo conversion, the balance plug can be used for charging and voltage checking.
bottom left, the Rexl spark conversion kit for glow engines.
Bottom right, Denso U20MU and Chinese 10mm plugs compared.
Pics: top left,Frank's neat 24v starter battery box. Christened the “no options” box (engines have no
options but to start).
top right, Jason Gazzard with his new Aeroworks 540T just after passing his wings test.
bottom left, Murray about to have another sortie with the club trainer, an electric Tower 40 Trainer.
Middle right, Peter Deacon with his “old faithful” Pawnee. Now repowered with DLE 20cc petrol.
Bottom right, Saito 3 cylinder 170. Runs superbly and being fitted to a member's warbird. Guess what
the warbird is.
Pics: top left, the retrieval team, Peter's boys worked hard for their free lunch.
top right, the boys had gone home so Marf gave a display of “seamanship” by losing an oar whilst
retrieving his Aquastar.
Bottom, Lake Pinot flying boat base. Three models airborn, pefect place, perfect day.
Dave Grueber's venerable Kadet Senior. Perfect on simple foam floats and great fun.
Tony Rodgers' Seawind. 1000watt electric powered. Well behaved on the water and impressive in
Flight box essential Ever wanted a bit of 5 minute epoxy out at the flying field? Well I have been
keeping the double syringe sort in my flight box. When I needed some recently I delved into my flight
box and found that the resin had leaked out. How did that happen? Well a while back I lent the stuff to
some one , the syringe tips were cut off then after use the push-on cap refitted. Heat and expansion
soon produced a gooey leak, and a few dollars down the drain. Well I have discovered that Selley's
markets a pack of three one use bubbles for $5. No more waste and mess! See pic below:
Robert Evans' flew his “plastic fantastic” Thunder Tiger Cessna with .91 4 stroke again this year.
The Inter-web Thingee
Here we go with another collection of interesting items from hyperspace. Those of you who have not previously
used YouTube much will by now realize that it is quite addictive and it's very easy to get distracted by the list of
similar sites shown each time you select something to view. I'd suggest that you skim through the list below first
and then go back to any areas that have attracted you, otherwise you may find, like me, that you have used up
your monthly broadband quota before the month is up. You may also see half the things I want to put in next
It's interesting to note that there are people who make their living from YouTube. A good example is Dave Powers
who produces videos, under the "RC Powers" name, featuring mainly park flyers. The idea is that he asks people
to register if they enjoy his videos, and when he has tens, or even hundreds, of thousands of regular viewers
registered, advertisers pay him to allow their ads to be shown. As you'll see he has a slightly zany, humorous
style, which most serious modelers would say promotes unsafe practices, but you need to see him as an
entertainer who appeals to young people (and he quite likely makes a couple of grand a week doing this).
YouTube - RC SU-47 CRASH!!!
Next let's look at another item from Yannick Barthe, my favorite full-size aircraft cinematographer (a bloke who
films planes). Normally we view aerobatics from a couple of thousand feet below. You get a completely different
perspective when the camera is on an adjacent mountaintop. Then you can really see the incredible gyrations an
Extra 330 is capable of - it even hangs on the prop like a model.
Extra 330 Display by Jérôme Cusin at Graitricks Moutier, Switzerland 2010 on Vimeo
That was spectacular flying and so is this - formation flying with model jets certainly can't be easy but Ali
Machinchy and Thomas Singer do a pretty good job here. I've looked at quite a few attempts at formating models
and none was nearly as good as these guys at the Florida Jets meeting last year.
YouTube - Florida Jets 2010 BAE Hawks Formation Flying
While we are on the subject of precision flying how many of you have seen a control line stunter in action. I
remember building and flying models like these, with coupled elevator and wing "flaps" they turn on a dime. This
sequence is quite long but worth watching, check out the facilities available for control line in Czechoslovakia and
the way these guys hit that 1 metre height so consistently.
YouTube - 2009 World Cup C/L - F2B Aerobatic Model Aircraft
Now here is a bunch of nutters. Not much precision in evidence on this video but I imagine you need a lot of skill
to stay in the air when about thirty other maniacs are trying to knock your model out of the sky. Goodness knows
how they keep track of their own model when they all seem to be the same shape with half of them the same
colour as well.
YouTube - 2007 Super77th.com Foamie Combat Slope Soaring
That's enough flying for a bit, lets have a switch to some precision engineering. First a bit of innovative work by
some unknown modeler. I am not sure why you would want a constant speed prop on a model, other than to add
a scale feature, but this is certainly a great piece of work and it's interesting to see how the Watt meter (indicating
power) changes with pitch changes.
YouTube - Scale constant speed variable pitch 4-blade prop for 60size RC airplane
Here is a rather lengthy video of a major engineering feat, a 9 cylinder radial engine. Most of the clips of model
engines I've found just show a run on a test stand. This one has the maker giving a good description of the
engine. So, who wants one?
YouTube - 9 cylinder model radial engine
If you answered no to that question, perhaps this will persuade you. This is Ali Machinchi again, flying his
GrummanTigercat equipped with twin 5 cylinder radials. The video is a bit shaky for a start, but turn up the sound
and just listen. Not many models sound as good as this one.
YouTube - Ali Machinchy with a 3W Tigercat
By the time this bulletin comes out the float fly will be history and I guess there will be a few who think they should
have fitted floats to a model. Here's a bit of inspiration for anyone who can't be bothered fitting floats but happen
to own a model with big wheels. I remember reading about crop sprayers in Africa skimming the surface of
irrigation canals for amusement but this group of South African pilots took the concept to extremes. It's been
widely copied by Maule and Cub owners but I've never heard of a model doing this. A good chance for a
YouTube - Landing on water without floats!
While we are on the subject of landing on water here is how not to do it. I don't know if he had passengers aboard
but if he did I would think they would not have been impressed. I am impressed with the Grumman Goose (I think)
though. It's one tough plane that can hang together through this kind of treatment.
How not to land on water - YouTube
Okay, enough hilarity. Lets wind up with some serenity. Yannick Barthe again, this time with a pair of very
graceful gliders just stooging around the mountains. Even the stall turns are things of grace and beauty.
The Poetry of Flight, Handiflight 2008, Switzerland on Vimeo
That's my lot for this month - I'm already looking for next month's collection.
Well, at the risk of being laughed at here's a pic of me actually flying and not yakking at our float-fly. The
photographer did not take my best profile, but from his shadow I know who he is! Marf.
Happy landings, Marf.