Monthly Archives: October 2011

See that bear?  Yes, THAT is the arrow shaft I am using for this tricopter !
Honestly, this is THE place to get graphite arrow shafts of ANY type. Just to
see this place and the indoor range and the trophies EVERYWHERE  is worth
the drive! But, I digress…

I have now made a new airframe with flight proven electronics. It is almost like the
first airframe although with modifications based upon “experience” .

The first task is a more robust tail servo mechanism based upon AlexinParis’ quick and dirty concept.
The helicopter blade holder is also just too fragile

This is actually very quick to fabricate and is of very low friction. The pieces of tube that are
wrapped with thread are just extra graphite tube cut-offs. The thread is just button thread
cyano’d on. The trick is, I used some 1/4″ polyethylene water tubing jammed into the graphite
tube cut-offs. I then drilled out the center of the green tubing to make a nice bushing for the aluminum tube
(that holds the motor mount) to pivot on.  The motor mount is made of plywood and while it is hard to
see in the picture, it has some fiberglass cloth re-inforcing the mounting to the aluminum tube pivot
that rides on plastic bushings that cost 1/4 cent. The servo mount is also fiberglass re-inforced to
the graphite shaft. This works really well, no slop, no friction, light weight, easy, cheap, fast.
What more do you want? ( Did I hear some joker say, “for someone else to do it”  ? )
Check out the undermount servo. Totally covered by the motor, no drag.

This is slick and light and after all is said and done, I don’t think I would do it like this again.
I mean look at it. Even though I am going to put a bumper on it, it IS vulnerable to a hit.
You have to remember that the airflow into and out of a propeller is pretty much  80% of the
flow is through the outside 20% of the propellers’ span.  So mounting the servo on TOP of
the boom next to the motor would probably have a minimal impact on the total lift and a BIG
improvement on the rugged-ness  ( is that a word?) of the airframe. Hey, next time. In the mean time
here are some more pictures of my tail servo set-up.

Next month we will delve into the upgraded power distribution network .

Stay tuned!

Rocket Bob Kreutzer

Easily bought,  easily built,  easy to fly and anything fits into it,  it came down to a Fun Jet being what I could get as a test bed economically.  Any motor with the smaller mounting screw circle(s) will fit in a Fun Jet,  swapping propulsion components takes minutes.  It’s thrust to weight requirements are so wide that anything that can physically be installed flies.  Further,  I have at least (5) high revving,  some never used,  motors weighing from 35 to 117 grams that either have to go into a (always a tight fit and easily destroyed) pylon racer or,  a Fun Jet.  And some more slower turnings from (17) to (100) grams for low velocity and quiet flight experiments.

I recently observed the flight of a really powerful Ultra Fun Jet at a foam airplane gathering,  like 6S LiPos and 800 Watts-in.  Although fast,  it wasn’t as impressive as I expected.  It’s an  X squared thing,  above a hundred and fifty miles an hour it doesn’t seem how much power you put to it,  it won’t go much faster.  And,  trying to impress the crowd,  the nose was broken off in front of us,  to sort of be glued back on  (crooked) right there at the field.

At first,  just looking at it,  the representatives of Multiplex (professional pilots included) weren’t all that impressed with the improvements to my Mini Mag,  even with the conversion to a bash plate nose with the motor behind the bulkhead,  “Sturmovik” armor and the notation “250th flight”,  it looks just about like a hundred thousand other Mini Mags,  abet with no landing gear.  Nobody else seems to have caught on to improving foam airplanes with fiberglass,  or folding props,  or higher cell counts,  or better motors,  or controllers that can be set for the correct lead.  After it took off straight up,  and just kind of drifted/careened/blasted all over the field for (30) minutes (on just one battery),  they all came over to find out “what do you have in that thing!?”.

That Mini Mag was then fitted with a 4S 1100 mAh (125) gram battery (Thanks NeuMotors,  I reconfigured those 3S ones you sold me),  (70) gram Hacker outrunner,  a Hacker motor controller that can be set for outrunner correct (20) degrees lead and a 10 inch Aero-Naut folding prop.  Vertical climb at a count of ten is higher then I can reliably estimate,  but about a thousand feet,  glide back down is a count of (170).  Weight,  added fiberglass included,  is about (750) grams.  It can fly at just above walking speed on up to being a slower pylon racer.  That is staggering performance,  it didn’t come cheap.

Although in truth an affordable Graupner (45) gram motor (may I recommend a Scorpions) on 3 or 4S with a (7to10) inch folding prop can be delightful too.  The (75) gram NeuMotors 1105 gave incredible mid to high speed performance,  but it was the low speed possible with the high quality outrunner and bigger prop that won out.  It turned out that (70) gram motors with their lesser requirements on battery capacity,  beat (100) gram motors on flexibility.

The Fun Jet Lite is going to fly even slower,  and faster,  at the down side of that pusher prop howl of fast combinations (a goal here is minimal noise) and the limitations of elevons.

This contribution is also to influence my future return to good status with the SEFSD,  and atonement for (Hey you Fool,  part of your airplane is missing.  Please tell me that dot way out over Shelter Island isn’t your airplane.  Oh no,  not another packing crate materials airplane.  Have you no respect for matching colors?  Even if you are wearing a tie,  you still have to have a shirt on and be upright to fly here.)  the older members suffered through,  while,  among others,  the Editor and Current President kept me flying when I have been almost,  but not quite,  completely broke.

Although in possession of a “stock” Fun Jet already,  it’s back in California,  and I’m in Recession Exile in Western Germany. At a big swap meet on the 9th of October 2011 (Sa.) at a moment when I was open to buy (and needed a ball point pen),  a dealer was selling off new Fun Jet kits including a bottle of CA,  and a pen,  for Euro39/$50.  No longer included here is the Speed 400 motor and prop.

The necessary pair of 6” extensions added Euro3,50/$5 to that.
Euro42,50/$55

(This article is too long for one web page.  Please download the entire article here – Ed)

Please download the referenced book also written by Carl called “So You Want To Larn to Fly RC“