Daily Archives: August 24, 2012

11 posts

The Prez’ Sez’ for August 2012

Frank Flying

This month’s ramblings will focus on Fire Safety.
Rule 2……………When in doubt refer to Rule 1………………
Seriously folks, if the incident appears to be getting out of control call 911 ASAP…….
We’ve been very fortunate so far and thanks to quick thinking on the part of some club members we avoided what could have been a serious problem.
Therefore, you will soon see various members carrying fire extinguishers (provided by the club) at the field. These were given and will continue to be given to those members who spend a great deal of time at the field and would be the most likely ones to help in an emergency.
These one time units cost the whopping sum of $18.00 at WalMart. Do YOU own one ?…………………If not, why not.
Rule 3 If you observe someone installing a battery that has just impacted the ground into another a/c , by saying “Well., It looks OK to me”!
Get ready to make that call!……………………Then inform me who the member was……………I’ll take it from there.
The rest of the common sense rules STILL apply, LiPo bags, balancers, sand buckets, proper charging, etc.

Please try to attend the general meeting on Saturday morning followed by Jet Day at the Bay……….

Hope to see you there
Semper Fi

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Frank’s Tech Tip

This month, our leader, Frank has some words of wisdom for us.  During a recent flight at Otay Lake with his Mentor he noticed the ailerons were very “mushy”.  Thankfully he steered the plane safely to a landing with rudder only.  After inspection of the plane Frank came to the startling conclusion that if you want good aileron performance, you must plug the aileron Y-harness into the receiver!  Good advice for all of us.  Thanks Frank.

Franks Tech Tip


You got ’em,  and we need ’em!

By Jim Bonnardel

After a visit to RC Expo last year I came home with a ‘roll’ of RC related decals.
I started ‘dumping’ my extra RC stickers inside our outhouse, and it didn’t take long before the ‘urge’ caught on.  I started seeing more and more RC decals being ‘splattered’ on the walls and roof,  and in a twisted kind of way, it made me smile.  It kind of makes it ours…. personalization if you will.

Well,  recently Spanky’s came out and replaced our outhouse because the door was coming apart, and you may have noticed that all of our RC Stickers are now gone.   Sooooo….

Drop ’em like its hot!  Give our crapper, your stinkers (oops… I mean stickers)! Now is the time to leave something in the head that everyone may appreciate, unlike the usual ‘deposits’…

I’d bet that nearly all of us have a ‘pile’ of RC stickers someplace in our workshops.
Here is your ‘call to arms’!   Don’t fight that ‘urge’..grab a stack,  and come help wallpaper the inside of the new head.

The Acromaster Pt.2

Continued from Pt. 1

An Economic Analysis

Before I buy something used,  I first need to know what it costs new.  And,  since I commute between Wiesbaden Germany and San Diego California,  two prices,  one for each end of the flight.  I can carry propulsion and a few batteries in my suitcase,  the radios and airframes stay where they are.

In San Diego,  when it comes to Multiplex I buy at SureFlite,  so their website was used,  where applicable.  Yes,  Hobby People will sometimes sell you the same stuff,  but good luck getting Multiplex replacement parts out of them,  they don’t want to be bothered.  At SureFlite they either have the Multiplex parts right there,  or will get you them (from Poway) for you in a week,  and the owner of the local store is a member of the SEFSD.

California taxes are computed in at (9)%.  In Germany any taxes are included in the posted price.  The Germans are puzzled by our American practice of adding the tax(es) at the checkout counter.

Acromaster airframe kit                           131-  The Multiplex kits I get in Germany are made in Germany,  the ones in the USA come from the Philippines.  I’m not current on comparing the two,  most likely if there is any difference it’s hidden in the quality control of the parts.

My pair of year 2011 Fun Jet kits,  one bought on Convoy Street in San Diego CA,  the other in Lampertheim Germany,  seemed identical,  except that the German kit no longer includes the Speed 400 brushed motor.

The German production Easy Star I may have had better matching of fuselage sides and wing halves then the ones out of the Philippines back in 2009.

The Fun Jet and Easy Star I have been discontinued in Germany,  where the Fun Jet Ultra and Easy Star II are now available.

Two HS-81s at 15.50                           34- As the current issue HiTeck (18) gram servos are the HS-82,  I take SureFlite is selling off their old stock.  I wouldn’t let the slight difference between HS-81s and HS-82s determine where I bought the servos.  Although they list the HS-82 as being digital,  if it’s that much to you,  please research the difference and report it as my Acromaster will be my first use of HS-82s.  I expect my airplanes to last,  at least fifty flights if not a lot more.  If I were building it new an Acromaster it would get a Metal Gear servo for the rudder.  The better impact capacity is why as from examining the movie made by a SEFSD members Telemaster with the camera facing rearwards that tail wheel really gets jerked around.

Two HS-65s at 33.95                           74- I had considered using my already sitting around HS-81s as an economy measure were I to start with a kit.  Saving (9) grams per servo would be worth less to me then seventy four bucks.  I’d gladly carry the extra (18) grams of on hand HS-81s in exchange for the better accuracy.  That keeping the airframe light is a good thing,  but not the whole picture.

Glue                                                        5-  If I built it new add ten bucks of fiberglass reinforcement to that.  Even the used one will get “beefed up” so it can withstand our landing on grass as a crop fields around Wiesbaden.

Prop (APC) 11X5.5 and collet                             10-  APCs are the standard included in Multiplex Germany kits both for Germany and the USA,  where they cost a lot less.  I prefer the Aero-Naut and Graupners even if they cost more.

All my airplanes now fly with Aero-Naut collets at thirteen dollars on up each.  See my book for beginners “So,  You Want to Fly RC” for details.  I’m neither embarrassed,  or proud,  about having to do everything possible economically.  If five dollar collets worked well enough,  I’d still be using the cheap ones.  If ten dollar Graupners were as good as Aero-Nauts…  To me propellers and their hubs aren’t the place to cut the budget.  As cheap and beat up looking as my airplanes first appear to be,  they fly well,  good components set up right where they matter,  and the skill to use them,  are why.

Extensions,  two at twelve inches         11-

Motor         (available mail order)                  81- That (105) gram motor costs $75- plus shipment in the USA,  or half what my same weight sport Plettenburg outrunner costs.  One benefit of the used Acromaster purchase,  comparing different motors and controllers, the Extreme proved to be poor quality i.e. poor efficiency to begin with,  the bearings quickly wore out ect.  Effectively by buying used I paid less for a motor then really good quality replacement bearings for my (125) gram Graupner.  I’d put new bearings in it anyway,  the replacements available from Boca Bearing are much better quality then the originals,  but the magnets broke lose too.

Motor controller (45) amps                  76- It’s not strictly fair to compare the German Robbe (40) amp motor controller included in the purchase of the used Acromaster with the (45) amp Hifel,  but if I were buying new in San Diego at SureFlite that’s what I’d likely get.  On reviewing the information,  and looking at the picture of the programming card ($10-),  the Hifel controller can control 2 to 6S LiPos,  it has a tacked BEC and has adjustable timing.

You have to watch it with the older non-tacked BECs,  as a consequence of having to dump excess voltage into heat the available amperage to the radio and servos at 4S was way down from the ratings at 2S and 3S,  as such they are not necessarily sufficient for the four servos of an Acromaster being put through it’s paces.  Everything could go along for a while,  and then you put in a new,  low internal resistance high Output C battery resulting in higher voltage at the motor controler,  the motor puts out like never before,  until the BEC quits,  taking the whole airplane down with it.

That being able to increase the lead from fixed 5% to an outrunner correct 20-25% makes about a one fifth increase in duration even with “sport” quality motors.  Although I’ve enjoyed thousands of flights with 3S LiPos and fixed timing,  to date,  Castle Creations oh so reliable and affordable motor controllers won’t go to 4,5 and 6S,  and the timing is fixed for inruners.  That could well change in the near future.

It looks like,  no doubt missing some bits and pieces (like paint),  about $430- to field a “stock” Acromaster with about the same equipment back in San Diego California.  Add to that the receiver and battery(s).

I’ve always maintained that if you are starting with nothing just go ahead and get the whole Multiplex package.  Hobby People’s website didn’t have everything individually packaged by Multiplex for the Acromaster,  Tower Hobbies did:

Acromaster Airframe kit                  $145-

Motor,  Prop and Controler           153-

Servo Pack with extensions          131-

Glue                                                  5-

Looks like $444-,  or about the same.  The HiMax is a little heavier motor (135) grams verses (105),  the servos aren’t exactly the same,  HS-85s verses HS-81,  but it’s a good match.  As luck would have it,  I have the specified HiMax motor and latest Multiplex controler already.  On thing I determined with the Fun Cub,  the big HiMaxes didn’t overheat despite the motor mount blocking off the airflow at the motor,  the lighter more powerful Plettenburg did.  I had to clearance around the motor of the Fun Cub and glide more to keep heat at the motor under control.

In Germany I used the Multiplex Deutschland suggested prices.  Since the majority readership is Americans,  who are not used to Euros,  the prices are adjusted.  If the Euro/Dollar rate is different over reports,  it’s because the exchange rate changes daily,  I report the prices at the time of the transaction.  As I write this,  dejectedly next to the window,  where outside it looks like a perfect sunny day (in Germany if it’s sunny go outside and play,  you never know when that might happen again),  except that with the mornings 12F and afternoons 23F,  it’s too cold to function,  the exchange rate for banks (what you see on the TV news and the fine print of the print newspapers) is Euro/Dollar (1/1.30).  Add five cents to that for the rate an individual gets for (1/1.35).

Multiplex Germany publishes suggested prices.  They are in fact what my local hobby store needs to stay in business.

Airframe         Euro140/$189-

Power Kit         Euro142/$192-  Two APC props,  different sizes,  a timing settable 2-6S (55) amp motor controler.

Nano Karbonites Euro28- each Euro56/$76-  Not exactly the same as HS-65

Karbonites,  the leads are longer,  all of them to date have centered to each other.

Tiny-S Euro17- each  Euro 34/$46-  Again,  not exactly the same as HS-82s

Or HS-85s,  longer leads.

Two twelve inch extensions Euro8/$11-

Glue         Euro5/$7-

It looks like Euro395/$520-.

But,  they have Internet mail order places here too.  Where you can always get a better price right up until the neighborhood hobby store closes.  They don’t all carry the whole program.  For reference,  one of the bigger mail order RC offerings was:

Airframe         Euro120/$162-

Airframe plus motor/controler/prop package  Euro252/$340-

They mention a super package,  which includes the whole radio ready package and a Multiplex receiver,  but they didn’t give a price.  Shipping for orders above Euro90- is free,  but saving Euro20- on an airframe means I soon will have no choice but to shop in the Internet.

The Package Arrived a Week Later

Well,  I hadn’t seen one in four years,  and nobody nearby stocked the kit,  so the size and proportions were a surprise.  A big thick symmetrical pair of wings that look stubby assembled to a surprisingly voluminous fuselage.  I E-mailed the seller back thanks,  it was exactly as described and began examining it.  Maybe attribute it to having started out with balsa,  and when I discovered that I could selectively strengthen EPP and Elapor foam with fiberglass,  which won’t structurally bond to the foam over the paint,  I immediately started sanding.

People show themselves in everything they do,  I wonder what somebody would think of me if they ever find that Easy Star I with the Aveox motor and fiberglass reinforcing sixty feet up in that tree somewhere in the Santa Ana river bed where it crashed on radio failure five years ago.  Or that found set out for the garbage,  balsa wing (paper and dope paint sanded off,  ailerons added and re-covered with heat shrink covering) with the a Depron/fiberglass body and brushless motored Graupner Taxi that went missing near the Rhine River somewhere between Bingen and Rüdesheim.  The original build quality of the Taxi indicated the owner did it without help or prior experience (never finished,  it wouldn’t have been able to fly as found),  that it sat in the attic for an estimated thirty years and was carefully set out on the street along with worn out furniture in front of a million dollar residence,  where a scrounger like me could find it,  and maybe make use of it,  said something about the first owner.  Both times three hundred bucks worth of equipment just gone.

It Started in a Mould

From the add description where the valuable servos (a hundred and fifty bucks new) have only five flights on them,  and oversize control arms,  the few dents on the leading edges and the tension crack in the paint on the fuselage right behind the main landing gear mount.  I wish I could have flow next to the previous owner.  He could have pulled the motor and controller in one minute,  and chopped the servos out for use in another project in five minutes more.  Either just the servos or motor and controller would cost new as much as I paid for the whole airplane,  which,  if it has the same number of flights on it as claimed for the servos,  only flew five times.  I wonder why he sold it,  but a thanks to him.  It has the older issue plastic motor mount.  It looks like about the same tail wheel mount that proved too fragile for extended use in a Fun Cub.  But,  I’m beginning to realize that my hundred flights airplanes aren’t typical.

The bottom of the nose was slightly cracked and repaired,  most likely from hitting the ground on a nose over.  It was decently painted in two tones.  Either the original builder used a primer,  or the paint reacted with the Elapor as sanding both the blue and orange resulted in an icky green mess that irritated my lungs and stank.  The wings leading edges were slightly dented up,  for no more then five flights the outer edges abraded.  Had the airplane had been used in a  crime (contributing to the delinquency of an adult wouldn’t count) there were debris embedded in it which could be analyzed. The right wings lower foam section didn’t evenly match the upper.  After flying with typical “minimal” level servos it’s always a surprise to see how much smoother and exacter even slightly better servos function.  The original assembly and painting was plenty competent,  if I was putting one together stock I would have done no better.  Things like not getting a perfect match between the Elapor components are determined by the staggeringly economical net cost of the kit and that’s just the way it goes gluing together a material that is inherently flexible and compressible.  Initial examination and sanding took three hours.

For reference sanding,  spachtel,  a layer of heat shrunk on packing tape at the leading and outside edges and fiberglass with resin reinforcement at the control arm and adjacent foam of the aileron took the right wing from (120) grams to (121) grams. That working over the wings after cleaning them up took an hour.

I had been paying Euro8/$11- for worthwhile name brand cans of spray paint that gave better results then any consumer level spray paint I ever used in the USA.  Just a thin coat covered well,  it stuck great to Elapor and the cans coverage went a long way.  I took the Euro6/$8- cans of the house brand back to the hardware store for a refund.  I wanted paint with pigment,  not clear with an accent of icky color.  The local artists spraying graffiti murals on approved places use Euro3- a can paint that’s better.  A Tau of Poo event,  how else do you determine the level of financial expenditure that provides satisfactory results?  The new paint, only a third of the area,  added (8) grams.  The wings are now clean and smooth,  however the mix of sanded off blue/green and orange/green with the new (expletative deleted) yellow and red over the blue/green looks awful,  even by my low standards.  It looks kind of like the airplane is healing up from acne,  skin grafts after being burned all over,  and leprosy.  I couldn’t make the surface treatment any uglier if I tried.

But fly it some first is my method.  Usually that determines what really needs improvement rather then just trying to anticipate everything first.  I often build two of a type for that reason.

So a tried and true Multiplex Acromaster airframe well assembled with what could be considered best choice servos and a decent paint job.  The motor is on the cheap side, I don’t expect it to either perform all that well,  or for very long.  The controller,  downrated by the latest expectations as of 2012 of being able to advance the timing to correct for an outrunner,  is only ok quality,  but it will go directly to 6S and can reliably provide sufficient power to the servos.  As shipped the APC 13X4 propeller verses a better performing and stronger Graupner in the same size is a toss up.  Sometimes I’d rather the propeller break then the motor mount,  motor or nose.

From experiments with the Fun Cub,  which weighs just about the same as an Acromaster;  4S 2200 mAh and a Graupner fixed 9X6 provided more thrust for flights twice as long when compared to the APC 13X4 on 3S 2200 mAh,  both using the same controller and HiMax 1130 kV (135) gram motor.  That big flat pitch propeller,  specified back when 4S motor controllers were exotic and expensive,  provides great low speed controllability,  braking in the downward sections and in general a poor mans constant speed flight profile.  It also hangs up and breaks at every possible opportunity.  In the Fun Cub the controllability on 4S was even better,  the constant speed aspect will have to be explored with the Acromaster.  The slightly higher weight of the 4S 2200 mAh battery verses the 3S 2200 mAh was just buried by the higher thrust and duration.  Think going straight up to two or three times the height restrictions at San Diego’s Mission Bay at a count of ten and taking three minutes to glide back down.  On 3S that was more like a minute and a half.

This Acromaster’s nose  was slightly reshaped to accept a folding propeller.  The linkage for the ailerons needs a heim full 3S joint as otherwise it demands the control horns flex.

Just what is this for a Motor?

In every speed shop in the whole world there is a standard question;  Speed costs money,  how fast do you want to go?

It’s subjective,  I had no idea three years ago that foam airplanes,  even with the motor and prop in front,  could last hundreds of flights,  or use propulsion components so far off from what everybody else was using.  But all it takes is one time taking off with the computer radio set for a different airplane to trash the whole thing.  Even in my reinforced foamies the motor can get broken.

There wasn’t much info from the web site of the American manufacturer (importer really) brand Extreme,  about the motor that came used with my Acromaster,  the most important parameters are (35) amps max,  (105) grams and 3 or 4S LiPos at (900) kV with an allowable of (350-450) watts-in.

You have to be suspicious of that kV number.  If you are buying NewMotors,  or competition level ones like Hackers,  you may expect that to be accurate to two significant figures.  That means if Steve and Jeff report their world class racing motor as having a kV of (3100) it may be expected to be between (3150) and (3250).  Check with them personally as maybe they can hit even closer!  It takes top quality materials and manufacturing to be that accurate,  real measurements and a willingness as a company to be honest.  NeuMotors even offered a meter to verify kV for a while.  Anybody else’s motors,  figure more like one digit accuracy,  or off by (10) on up to (15)%,  maybe deliberately to con the customer into thinking they have more performance then they paid for.  Keep that in mind when your results don’t match P-Calk,  that any calculations or program’s accuracy is limited by the inputs.

If you ever wonder why my stuff puts out more power then yours,  some of it’s because I didn’t believe what the package the motor came with was marked as and fiddled with prop sizes using a watt meter and my fingers as a thermometer until the motor was running on it’s limit AND matched to the airframe.  The results are still sometimes a surprise.  That’s part of why I destain reports where all they tried was one combination.  Then too,  I like a “burst and glide” flight style reminiscent of slope soaring,  and holding my breath hunting lobster.  That may explain why my average flight times are about double what the magazines report.

So all I really may expect is that the kV of this motor is likely between (800) and (1000).  At this price level you must expect that individual motors of a series will not match.  There is insufficient information to model it on the P-Calk virtual dyno.  Luckily,  I have a watt meter,  like to fiddle and have been using motors in this size and kV for a while.  Test and tune will decide what works.

The 4mm shaft (interestingly with the brand name Axi etched on) was hack-sawed off shortened.  Turning it over in my hands the bearings feel smooth.  Weird,  the front bearing,  that can be seen,  is about average size for this weight of motor,  but the rear one,  inside the bell where it can’t be easily seen,  is very thin.  The inward rear bearing of an inrunner is usually one size smaller then the front one,  but this is way smaller,  like three sizes down.  That “mini” size bearing may have kept the initial price down.  Maybe it allowed larger coils for higher magnetic flux density,  getting an improvement in power.  It brings suspicions of poor durability as lately it is the bearings that give out ending the service life of brushless motors.  Something you won’t read about in reports made after just a few flights.  I own this thing,  I’m going to use it.

My similar Graupner (125) gram motor,  run at the much higher shaft RPM on 3S LiPos instead of the 2S LiPos Graupner rated if for,  held up for (75),  each and every one was a worthwhile life’s event,  flights.  I’d spend the twenty bucks for new bearings,  but the magnets came lose and I already have better…  One clue with bearings that small as the Extreme’s,  keep the RPM down.  In particular don’t screw up and over rev it with no load (the prop off) as you can wreck the bearings faster then you can pull the amp stick back.  Me,  I don’t ever run up an unknown combination without an amp meter connected.  Not even changing the prop diameter by half an inch or the pitch by half an inch.

The cheap motors,  I reran the measurements every twenty five flights or so as the increased drag from the bearings causes increased wattage draw burning them up.

Now days I just buy better motors in the first place. That,  was two years ago sixty dollar,  now eighty five dollars new,  (80) gram Typhoon motor puts out about (85)% of what the same size (70) gram NeuMotors one does for about (85)% of the duration,  at half the purchase price.  The Typhoon cogs between magnets,  you have to deliberately turn the NeuMotors,  the magnets and coils are that much better.  After a hundred flights (proped as near as possible to the manufacturers (350) watts-in rating,  the same size NeuMotors go to (400) watts-in,  although now obsolete,  the same size HiMax was rated at (300) watts-in) the bearings of the Typhoon are just starting to show some wear in the form of slightly higher current draw,  the Neumotor is still as perfect and smooth running as when it came out of the box and the dust shields wore in.

As for that almost

The Acromaster Pt.1 & 2

This is an original year 2012 for the SEFSD extended article covering the whole experience of acquisition,  modification,  fiddling with different propulsion components and flying an Acromaster.  If you are looking for a shilling,  magazine style,  I just put it together and everything is great,  article that  glosses over anything bad,  doesn’t at least try other equipment,  lands their RC airplane at flying fields only,  and doesn’t fly it long enough to uncover weaknesses,  go check the Internet.  There are many worthwhile articles with pictures covering the assembly available there.  Why the rest haven’t caught on to improving the weaknesses,  or trying different combinations,  is a mystery to me.


I usually don’t trust a report unless the pilot has made at least fifty flights.  I stopped my fiddling with my Acromaster at forty five flights because of it’s failure to satisfy.  It’s a fun airplane,  but with an airframe and airfoil prioritized on older,  heavier components,  it’s really for close in ( a hundred yards) and slower flying,  maybe modern airframes have passed it by.  The Acromaster is durable,  but no match as a flier to the modern,  if far more fragile,  similarly equipped ARFs,  or even the latest from Multiplex itself.

If you just want to cruise around the flying patch,  this isn’t the right airplane either.

Although it can buck wind better then a Parkmaster,  and flies slower then a Gemini (it was flown next to stock,  if reinforced,  ones often) either of them,  depending on wind,   are more fun (a lot more fun) to fly.  One nice thing about the Acromaster,  even without modern gyroscope stabilization,  it can buck wind better then the flat plate equivalents.  If you accept it’s inherent lack of self righting it makes a good general purpose sport airplane too.  Those thick trailing edges are a poor man’s constant speed control (and restricts the oh no speeds for pilots of moderate skill),  at low speeds they don’t matter,  at speeds go up they slow the airframe down,  something which the recommended large diameter very flat pitch propeller does too.

You have to use good servos to really make use of the Acromaster.  As with any airframe cheap motors,  controllers and batteries will cut into performance more then any magazine article will admit to.  I’ve been at it long enough to get by with a standard four channel radio,  this one benefits from separating the ailerons to different,  tunable channels and needs exponential if you are going to hover it.

With large control throws though it could hover and pretty much do outdoor what the indoor crowd enjoys,  but we have easily affordable Depron flat plate fliers that outperform the Acromaster for that type of flying at Mission Bay,  out doors,  as long as there is nearly no wind,  at a lower price.

Even good quality servos don’t always match,  which was an issue with this specific airplane,  check the throws on the ailerons to make sure they are the same!

An attempt to use an inexpensive motor,  which  proved to be just plain cheap,  was frustrating,   get at least the Multiplex recommended one.  Attempts to use a lighter Park Master motor ((80) grams verses (135)) on 4S LiPos didn’t work out.  The airframe needed both the weight forward and the occasional burst of torque for worthwhile flying,  the smaller motor overheated if flown constantly at (225) watts-in.  The best choice was a high end (105) gram outrunner (Plettenburg) on a high end (Hacker) motor controler on 4S LiPos at about (350) watts-in.

It would come down to what and where you expect to fly,  for flying the full aerobatic program(s) at Mission Bay you might want a modern plywood/balsa ARF or one of the newer Multiplex offerings instead.  If your reflexes and eyesight either never were all that good,  or are falling off,  the Acromaster could be a great choice.  The next best alternative for the slow of reaction group who want to try acrobatics might be a Twin Star II with modern equipment at about 2/3s the cost.

The Acromaster is a Slow to Zero Ground Speed Airframe

Although there is no exact visual match in Real Flight 5.5,  that isn’t much of a disadvantage as there is a whole range of similar virtual airplanes in there.  In contrast to some other Multiplex airframes,  the Acromaster isn’t dramatically different from the norm for it’s type,  just the opposite actually.  It is in durable,  affordable foam with a four foot wingspan an F3A type RC flying machine with the neutral flying to be expected of that type.  Conventional aerobatics airplanes expected to fly a standard pattern of aerobatic maneuvers are more shades of the same thing then different from each other,  going too far outside the performance envelope would be a disadvantage.  With it’s moderate wing loading and huge,  low speed control surfaces it can be stable for traditional aerobatics,  or wild for the newest ones.

Depending on the adjustments at the control surfaces throw and power the Acromaster can be tuned to the skill level of the pilot,  who should be well beyond the beginner stage.  The Acromaster can be a wonderful second aerobatics RC airplane capable of about any maneuver an RC airplane can perform,  and cause to smile for pilots nearing the end of their life’s journey too.

One thing the Acromaster isn’t,  with no self-righting characteristic,  it goes where it’s pointed and keeps going so until directed differently,  the pilot must regularly exercise his will to keep it flying.  With it’s moderate wing loading,  puffs of wind can change it’s direction.  If what you really want is something for relaxed extended just give a direction now and then cruising around the flying patch,  get something else.  It’s not that this bigger flies better airplane isn’t,  for it’s type,  stable,  even in the wind.  But,  if you get distracted for just a couple of seconds,  any F3A like airplane is already into the ground.

The range of satisfactory propulsion  combinations far exceed the specified ones.  Due to the short landing gear it needs a decently flat,  even,  wide,  place to put down on (or long grass) although,  with nothing more then the addition of some packing tape to the wings leading edges (and an acceptance of breaking large diameter APC props),  it can tolerate the weathering shredded wood,  brought to a stop by a small bush,  of a just off the runway landing many times.

Let’s Separate the Durable from the Competition Stuff

Although no longer under contract to Multiplex,  the German ace RC pilot Martin Müller reportedly had a hand in laying out the Acromaster out.  I saw his brother fly last summer demonstrating the Multiplex line up,  it reminded me of landing on the mat looking up bewildered at martial arts experts.  My average reflexes and eyesight set a strict upper limit even back then.

But I’m not going to be torque rolling between trees,  or breaking the laws of physics with my Acromaster.  Nor is anybody at the national or international level going to be entering an Acromaster in competition.  Thanks to it’s size,  medium wing loading,  and consequently lower speed in both airborne maneuvers and landings,  even marginal reflexes and eye sight are entirely adequate for sustained use of the Acromaster.  A pilot with below average flying skills can enjoy flying,  and look good,  with an Acromaster.

Although somebody can screw up the assembly of anything,  it looks like it would take some real fumbling to get the Acromaster together so wrong it couldn’t be used after somebody that knew what they were doing set it up.  As always,  one of the benefits of the SEFSD is a collection of other pilots ready willing and able,  if you just ask for help,  to verify the serviceability your equipment.

I’d like to remind our expensive and hand built contingents of a one sided offer. For the few minutes when somebody has a three thousand dollar airplane in the air,  or something special with dozens and dozens of hours of building invested,  I want them to be able to concentrate on flying without the distraction of my careening around.  If it’s just a couple of us in the air and I can land off field,  I’ll stay clear of a box around the runway.  If I need the field to land on,  before you send your airplane up,  I’ll land and watch as I don’t want to risk a collision.

Just tell me when you want to fly,  I’ll get my foam and fiberglass buzz bomb out of the way.  I can take the wings off of an Acromaster and toss the thing in the back seat,  they can’t.  I may be a flying fool,  but I’m a courteous fool who will enjoy watching them fly.

I did a rethink about how to best share the common airspace a while back.  That being hit from underneath by an expensive motor sail plane on one of it’s first flights while it’s owner was fully focused on just his airplane,  and a scale pilot landing off field because I left my flying wing on the runway a couple of minutes,  changed my attitude. Among many other problems of brain damage during 1997 through 2000 my sense of time was screwed up along with a inability to maintain attention of what my right eye registered.  Although we always did  clear the sky when the F5B contingent showed up,  it was the at appearance of the F3A members when I decided I just didn’t feel right about mixing my “lowest net cost per flight” stuff in with their fragility and investment,  since they too tended to fly after the Mission Bay wind tunnel set in around ten am. At first the expensive/fragile stuff pilots had to be convinced I was genuine about the willingness to make room for them that I consider to be courtesy.  They fly for seven minutes at a time,  I may be blasting around for hours.

Furthermore,  if the night before,  you consumed your commission from a local vintner for assembling his airplane,  or,  just had dental surgery,  don’t fly RC until you recover.

How to Get an Aerobatic RC Airplane for a Minimal of Cash?

Being almost,  but not quite,  completely broke,  makes justifying a new airframe kit and all new parts difficult.  Wanting something really aerobatic,  the choices were;  A Gemini,  which a friend already has (landing in Norco or Jamul would chew it up),  a Park Master,  for which there is already one in the group (I’m going to get one during my visit the USA trip the spring of 2012,  it won’t be landable stock with a fixed propeller and landing gear at Norco or Jamul either),  or an Acromaster,  which I haven’t seen one really fly yet.

Sitting out late January and the first half of February 2012 because of the worst cold in Germany and Europe since 1956 (and a recession in the USA that seems to have no end),  the two of us elected to go flying right near home instead of getting up early on a Saturday morning for the hundred mile each way drive before dawn over a frozen autobahn to the Sinsheim RC swap meet.  We’d have enjoyed looking at all the fancy/big/expensive stuff,  blown some budget on small stuff and ohed and ahed at the Depron indoor airplanes flight show.  But it’s a cost verses benefits thing,  would the savings on any purchase and the entertainment of the only RC event during the “dark” months of the year justify the drive?  Our Editor asked for some coverage of events in Germany and Europe,  from October through April there aren’t any!  At least not outside.

So we just went flying instead.  My Depron biplane wallowed around,  I soon afterwards junked it.  Before I try that again I’m getting myself some help,  see DW Models.  ´

The friend alternately flew his Park Master and Gemini so we could directly compare them.  No,  the motors don’t put out as well with the batteries that cold,  nor do the pilots perform as well,  but it was still worthwhile flying with two great airplanes!  From past experience that kind of cold can slow down cheap servos,  our minimal to better quality ones did fine.

That springy single wire landing gear of the Gemini,  which is also common to the Acromaster,  Fun Cub and Mini Mag,  is holding up sort of ok (broke the first plastic mount at twenty landings,  the second is holding at thirty more) landing in long grass,  it was later replaced with a carbon fiber one.  The Park Master’s landing gear at the fuselage,  after fifteen flights isn’t as durable.  The folding prop in the Gemini (had to clearance some and toughen things up with fiberglass) ignores the headstands.  The lighter Park Master with it’s slightly flexible APC slow flier prop,  at least the nose is holding up,  no prop has broken yet.  In flight the Park Master covers the slow for Indoor like shenanigans (zu Deutsch Strolchen) to medium speed dynamic aerobatics,  the Gemini the medium on up to a little faster speeds for classical aerobatic flight.  The Acromaster is about in between.  Unexpectedly,  the flight characteristics of all three over lap a lot.  We get way longer flights then the magazine authors report using just ordinary equipment although,  being the biggest,  the Acromaster flights are the shortest.

Although it might seem that the asphalted farm access fields at three paces wide and km long might function as a landing strip,  our experience has been that even puffs of air at the airplane,  which we can’t feel from where we stand,  are enough to move the airplane sideways into either the rougher sloped grass or mud faster then we can respond.  My friends that learned RC partly on simulators all have difficulty placing their landings,  on a computer I can’t do any better.  As a former balsa RC airplane slope soarer,  I am an expert at landing in the real world.  None of us can reliably hit a ten foot wide road if there is any wind or thermal at all.  Our favorite place to fly is down in a bowl,  the wind overhead tumbles through in an unpredictable manner.  It’s so unanticipateable that once,  twenty minutes apart,  at exactly the same place sixty paces from where we were standing,  we both tumble stalled Mini Mags clear to the ground from straight and level ten foot up.  Unknown to us,  as the headwind,  swirling backwards from the clouds overhead,  passed over the airplanes,  they quit flying at the abrupt reduction in airspeed.  Our usual two hour flying session that clear,  sunny,  windless,  otherwise perfect day was cut short by frozen hands in the 20 F cold.

A week later I crashed my latest project,  a Dog Fighter Lite (what a squirmy airplane to fly,  rocked by the wind a hundred and fifty meters out,  unable to determine which way it rolled due to flying near the sun,  two seconds later it was junk),  after getting enough experience with it to conclude it was a wrong direction.  One useful result though,  attempts to lighten it up with a smaller motor and moving the battery all the way forward didn’t really get what we wanted,  a useful speed reduction,  since the weight reduction was minimal.  Even if the tuning motor in the Gemini can put out more power then desired,  both the Dog Fighter and Gemini airframes still need the weight up front for balance.  I’ll rather carry a bigger motor or battery then lead.

Of Servos and Quality Control,  of Cabbages and Kings

Since the propulsion of Multiplex airframes can be radically changed in under an hour with just hand tools,  whereas the servos are glued in,  the servos are one of the bigger choices in building up a new foam airframe. An Acromaster is capable of both worthwhile semi-precision aerobatics,  and the wildest of the new stuff.  So if you can’t afford decent servos,  you need a different airplane. Try a Fun Cub,  with it’s also twenty to forty dollar less expensive airframe that takes the same size servos (and many of the same propulsion combinations) if fifty bucks more at the servos means that much to you.  Just don’t expect nice balanced aerobatics for the seventy five flights or so until the hinge at the wings just past the spar becomes apparent.

We found out that the Gemini really benefits from servos with first rate resolution i.e. HS-65s.  With the better precision it turns into a first rate aerobatic combination with which the pilot knows anything happening is a result of him at the controls,  not random wandering of the servos.  If we wanted to improve the precision of the aerobatics the next step would be gyroscopic stabilization,  not better servos.  Then we’d need to get the overall weight down,  a (100) gram high performance motor instead of (135) grams HiMax,  4S instead of 3S LiPos moved forward,  and a three bladed prop for more ground clearance.  After that pilot skill and the flexibility of foam set the limits.

In my Blizzard,  I really didn’t see much benefit in flight from better (8-11) gram size servos,  except maybe that the Karbonite gears can withstand a rated four times more landing impact then the standard plastic ones.  But the Blizzard is a semi hotliner for drawn out,  fast,  graceful maneuvers,  not precision aerobatics.  Since at the landing the Blizzard neither does a headstand or spin,  unless you hit so hard the airplane is a write off anyway,  and it needs less aileron throw then Multiplex recommends,  at my budget I’d go standard servos in both wing and tail for a Blizzard.

In my fifty first flying wing,  a little bitty thing from Hacker with great propulsion and the best cut EPP I ever handled (that’s odd,  it was a little more expensive then the usual stuff,  about a quarter more,  and yet it flew a lot better and half to twice again longer with the same batteries as compared to others that looked just about like it),  better servos DID make for an improvement.

Where a manufacturer offers a range of gear material/strength,  the stronger material alone,  as least as reported by the manufacturers,  who don’t as a rule quantify free play in the servo’s,  doesn’t always benefit precision positioning,  the servo’s electronics have to be upgraded too.  In practice,  the HiTeck/Multiplex Karbonite gear train has less slop then the standard plastic one,  in addition to the servo’s electronics having better resolution and centering.

For the Park Master,  it’s a question of budget,  both HS-55s and HS-65s can function,  the better servos make a better flying airplane.  But the lessors aren’t at that much of a disadvantage particularly at the lower speed range,  except for hovering.  I can’t put it to words,  just think about the fifty bucks additional for four first rate servos over the couple of hundred flights you and your Park Master might make,  verses putting gas in the tank to get to the flying field.

There is a bewildering plethora of equipment offerings.  For which I can only remind you,  when you are buying things new,  you get what you pay for.  If you are trying to compare otherwise similar servos/motors/radios/airframes ect,  the higher price will determine which one is the better quality.  Quality isn’t linear with price,  economy of manufacture and marketing can make some difference,  sometimes the higher price is complexity you don’t need,  often better materials don’t show their advantage until the cheap stuff gets some use.  I’ve been at this RC bit a while,  over time,  on the average,  if the items are otherwise seemingly identical,  the more expensive stuff always functions better.

But,  if you spent too much on some parts and not enough on others,  don’t forget that all it takes is a single under performing component to wreak everything. Lately for us in Under Igstadt bei Wiesbaden am Rhein,  it’s the transmitter! If you don’t have enough experience to know what works and what doesn’t,  ask for some help down at the field.  Bored,  I sometimes read Internet threads,  half of all of them are people wondering why things don’t work right,  which when you recognize the cheap components that don’t work as advertised they are using,  that’s the answer.

Sometimes it’s about quality control.  I have had four samples of three $4- (8) gram servos from four different cheap manufacturers.  In two groups one out of three quit,  one of them intermittently.  One group all of the teeth of the output shaft at the control arm just disappeared over two hours of flight. Some of the gear trains were full of slop.  All of them the internal variable resistance they use for positioning corroded during storage in a year.  They intermittently have double neutrals (sometimes they come to a neutral stop at different positions),  and even when they wear in they don’t usually have matching neutrals to each other. That means the length of the control rods,  and with it the geometry of the control surface travel (a continuously varying relationship between transmitter lever and throw at the control surface set by the geometry of the parts),  doesn’t match at paired (aileron) servos unless you can separately zero them at the transmitter.  There is noticeable slop in the gear train.  Over a year the housings go brittle as the cheap plastic finishes curing.  So much for any repeatability or precision as part of a flying machine.

Still,  in a hand built Depron Event 3S,   cheap servos are part of a very entertaining combination.  Partly because it’s a great design and built straight,  and maybe at that low a speed a little imprecision at the servos isn’t a deciding factor.

Having bought and used twenty inexpensive (8) gram servos at Euro5/$7-,  at a time when I couldn’t afford anything else,  I was glad to have them.  They performed fine for slewing Easy Stars and Sturmoviks  and Depron Ugly Sticks around.  Some of them lasted past a hundred of my “flown hard and put down wet” flights,  I haven’t worn any of them out.  They were even an ok choice in a “lets use what I have laying around” Mini Mag and two meter,  one speed only (slow) motor sail plane.  At that moment the difference in price between “free” (I had them already) and having to spend fifty bucks to get new ones justified the lesser controllability.  If I have to chose between fitting a friends Mini Mag or Merlin out with on hand $7- servos that I know work,  and better cash outlay at $12- each for better quality new ones,  or having the gasoline in the tank to go see him and fly,  the cheaper ones will get used.

And sometimes another pilot just clearing out his accumulation by selling me his slightly used RC airplane brings me into contact with “Brand X” servos,  many of which do function satisfactory.  At around the (18) gram HS-82 size on up a lot of the cheap servos start functioning ok,  it’s the small stuff that seems to be the worst problem.

Back in 1998 when Wayne Walker offered to sell me some JR servos,  at a time when the (8) gram size for use in a Speed 400 pylon racer was uncommon,  I wish he could have put the difference to words.  Thanks for putting up with me during those brain damaged four years.

Just my luck,  left over from more flying wings then the Harbor Soaring Society  allowed meI have half a dozen decade old HiTeck HS-81MGs.  In case you were wondering,  my Fun Cub HS-81s are in their fourth airframe,  they have (600) flights on them.  Although flights then in foam flying wings were much shorter,  and the landings were often violent,  some of my HS-81MGs have a thousand flights on then.  My pair of Mini Mags with their HS-55s are doing fine at (350) flights,  including more then a few “why didn’t it break into pieces?” impacts.

Considering the precision aerobatics an Acromaster,  Gemini or Park Master can perform,  and that the choice of servos must be decided on before gluing them in during assembly as swapping them out involves cutting,  patching,  using expletatives the Editor deletes from this publication and so on and so forth,  cheap servos glued in would be false economy.   I can swap out a crummy performing motor,  or controller,  or prop assembly anytime in a Multiplex airplane…

The Acromaster Adventure Begins

Encouraged by the friends success at E-Bay Internet auctions (a new in the box Twin Star II that arrived by mail for half what they cost new,  a worthwhile used Blizzard he drove over to pick up for a third of new) I was the top E-Bay bidder on a,  reportedly,  slightly used Acromaster at,  with shipment,  Euro120/$162-.  Included were two HS-82mg (Metal Gear) fuselage servos (including extended arms for wild minimal zero speed maneuvers like hovering),  two of the much better then HS-55s resolution with stronger Karbonite gears HS-65 wing servos,  an unknown ( to me) (350-450) watts-in Extreme Flight 2818/900 outrunner and an ok Robbe 2-6S (40) amp 2-6S tacked BEC motor controller.  I had five 3S 2600 mAh NeuMotors batteries that should work with it,  plus some 3,  4 and 5S 2200 mAh ones.  Although there are two motor mount circle size motor plates,  I have both and a selection of propulsion already on hand.

To go to the end of the adventure,  an average,  modern “building,  what’s that?” RC pilot would have been better off just buying average (or better) quality components new and having our F3A contingent check them down at the field.  We didn’t do all that well with the used Blizzards either.  Too many hidden things wrong,  like crash damage,  parts that were too inexpensive,  poor initial assembly ect.

I used a Ds6i computer transmitter and AR6200 receiver w/satellite receiver.  According to our advanced pilots,  a computer radio with it’s exponential curves for coordinating control throws is a big help with this type of airplane,  they are right.  I flew mine first with standard settings,  then moved to the more advanced control throws tuning. An Acromaster flies fine

Another Hobby Shop Closed- Goodbye Sureflite

By Steve Belknap

Sad news for those of us who still frequent the local hobby shops.  Pandi’s Sureflite has closed for good.  I don’t have the details why, but I’m sure the economy may have had something to do with it.  This story is all too familiar for struggling businesses of any type, especially those who face cut-throat competition from overseas suppliers.  I wrote a short article expressing my thoughts on this here.

I personally would like to thank Pandi for his generous support of our hobby over the last decade or so.  He has been an unwavering advocate of electric flying and a friend to all local hobbyists.  Please express your gratitude next time you see him.

Please use your local hobby shops or they will go away.

BOD Minutes for Aug 2012


Update on l tower and FAA stuff. Nothing new to report for now in regards to FAA. Tim reported that AMA has made some changes to FPV rules including higher weights and changes to maximum speed and buddy box requirements. There is need to work on club rules regarding FPV operations as they relate to SEFSD operations.  Will have a FPV into at meeting in Sept general meeting.

Discussed club instructor status was discussed.

Field work update by Frank and Jim.  Jim presented proposal to vacuum the field with a truck. Discussed options. Friday AM at 8:30 to try vacuum truck and rolling with water.

Revisited signs again…. Chuck will not be dealing with the signs from now on. Board discussed configuration of signs. The configuration of the signs was discussed and it was proposed that there be a single large sign. The proposal was passed by a majority.

Discussed fencing and possible improvements. Proposed  replacing the fencing and top pipes and install new net type fencing. Approved by all present.

“Right of entry” update update from Ray. Ray reported that the ROE is making progress through the city process.

EMAC report from ME. 12 pilots for last EMAC. Chuck proposed a sub class where a more skilled pilots helps people in the lower classes. Frank will promote  a “novice” class to help increase club participation.

New business:

Safety report …discussed fire at field and what we should do to prevent future problems. Jim proposed club give away a fire extinguisher as a club give away.
Club will buy them..Frank will purchase them from the PX.

Membership report: Club now has 270 paid members.

Future events  report by Tim Attaway: Sept 1 will be poker fun fly. Tim discussed rules and proposed club buy pizza for after event. Approved by all present.

Went over calendar. Jet day by the bay for August will be run by Frank G.

Frank discussed having poles for speakers included sign posts. Will use some electronics in trailer for club events. Chuck Grim will help get the equipment to Frank.

Discussed indoor flying at the different sites. Frank talked about having a west coast “electric E fest” in the future in cooperation with other clubs in the area.

Next bod meeting sept 5

Meeting over at 9:00

Interesting Bits






Sean’s Sureflite C-180 Build


C-180 Fuse

The C-180 build was very easy.  Frank had also supplied a paper pattern for the tail feathers.  Sean decided to make them from 3/32” balsa sheet instead of the suggested 1/8” to keep the required nose weight down.  It turned out to be a good choice.  We then rummaged through my old rolls of covering material and found some rolls of lightweight transparent blue and orange.  He used a couple of the 1/16” laser cut ply control horns I used to include with the kits I made.  Hinging was done with hinge tape.  Control linkage was yellow Sullivan sleeve and .040” music wire.  Servos were whatever we found in our big box of old servos.


Tail Wheel

He added a tail wheel to make the ground handling easier.  A piece of .040 MW and a bit of fiberglass for reinforcement helps keep it all together.


Main Gear

The main gear, and the tail wheel, are from my fifth crashed Mini-Ultrastick pylon racer.  The main gear was shortened by cutting off the lower parts and re-bending and drilling for the axels.  I small piece of 1/8” ply was glued to the lower part of the fuselage so the main gear screws had something to attach to.  Even used the Ultrastick wheels.



Sean decided he wanted the wing attached with rubber bands.  You can see the 3/16” dowels and backing plates in the pictures.  He just located them in a spot that looked correct.



The kit as supplied did not have a cowl.  I thought we could make a quick balsa mold and pull a few cowls on my vac-u-former.  I went straight to the internet and looked at pictures of C-180s for the basic shape.  What I came up with was something a bit longer than what the original kit maker had in mind.  Still, it looks OK to me.  An added bonus is that the cowls have the authentic wood grain look of the full size. . .  Sean put the motor on a block to extend it forward.  He angled it slightly down due to the high wing.  A generous coat of Krylon H2O paint all over the fuse made it look better.  Frank had also supplied the window decals.



The motor is a Scorpion S-2208-30 and used a 3S-1500 battery.  Prop is a 7×4 APC.  Has more than enough power.  A 2S pack and a larger prop would work well also.


Wing on

The wing was lightly sanded and covered.  I thought it would be a good idea to add a couple small patched of fiberglass and CA to the LE and TE areas where the rubber bands stretch to keep them from digging into the foam.  Sean did not add ailerons.  It just doesn’t need them.  He did entertain the idea of making it a night flyer but didn’t get the time to add the lights before going back to CO to school.

All up weight is 20 ounces.



This little gem couldn’t be easier to fly.  It took almost no trim.  On full throttle it climbs like a helium balloon.  It lands with no effort.  For all you who have one from the meeting, put it together!  If you want a cowl, send the editor an email.  I will make one for anyone who is serious about building one.  I may also make a few cowls from a mold of one of the original shorter cowls as well.  It is about 2/3rd the length.



If you make one, send pics to me!  I’ll publish them.