Conference vmszoo::rc

        The lightest RC model I've ever heard of was a radio controlled
        model rocket glider, and weighed all of 35 GRAMS (1.25 oz)
        including the rocket motor! The model itself wasn't much more than
        a 12" span HLG. The electronics were a handmade micro-albin
        superregen RX driving a handmade pulse actuator and 2 hearing aid
        batteries for power. The rocket would barely make it off the 3'
        launch rod, so the rod was placed on the edge of a slope soaring
        cliff for the flight. I have plans of this model somewhere, along
        with RX and accuator construction information for anyone foolish
        enough to want to build something this small. 
        
        20 ounces almost sounds like an excess compared to that.

Ken Willard built a peanut-sized cabin biplane in the late '70s;
I have the article around somewhere.  That is the smallest I've
heard of using conventional RC gear.  There are others using
superregen receiver/escapment, the most notable being a very
tiny slope soaring glider, I think its span was around 10", that
Bill Winter wrote up in his column a few years ago.

I've got a 30" span model that I finished over a year ago but
haven't gotten around to flying.  I've had trouble with the .020
engine, and the radio has been swapped around for higher priority
projects.  Its rudder-only with a Tower micro system.

If you haven't, be sure to check out Eloy Marez's Electronics
column in Model Builder; he mentions "Wee RC" frequently.

BTW -- I've been experimenting with cardboard as a building
material, using a 36" span Northwest Dakota as a test subject. I
mention this because I have hopes that it may be a viable
material for small models (and large too).

So far the results have been mixed at best: the material does not
have any significant working advantages over balsa, and does
suffer a weight penatly, though not as bad as foamboard.  It's
also slow to glue, since the thing that works best seems to be
Titebond.  I'm planning to experiment with celuloise cements this
week. 

I was pretty excited about the stuff last week.  Then I finished
a wing and it turned out to be twice as heavy as a conventional
wing!  When I finish the Dakota I'll have enough experience to
file a note on cardboard. 

    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    I'm also a fan of small Models. I have built a Ken Willard designed
    kit called the 'Roaring 20' (kitted by Top Flight?), which was 20"
    span. This was powered by a Cox TD.020 and had 2 channel Mini Sanwa
    radio.
    
    In the past one of the favourite radio's for small models was the
    Ace pulse proportional single channel gear. I built a twin
    rotor autogyro for this, again powered by the TD. This came to an
    unfortunate demise downwind in some gravel pits, when I flew it
    in too strong a wind!
    
    My father has built a 7" span Delta for fun. This was powered by
    a scaled down version of the Mills 0.75cc diesel engine (about 
    1/3rd capacity) and had a single servo from one of the new light
    weight radios.
    
		Andrew

    
           I am presently building a prototype wee rc receiver. It uses
    the Signetis TDA7000 FM receiver on a chip sold at radio shack.
    With only one tuning coil it should weigh no more than 10-12 grams.
    If it works out, I will build another using its surface mount 
     cousin and surface mount caps etc. It might weigh as little as
    5-6 grams.  With silver oxide batteries and an appropriate servo-
    actuator an all up weight of 20 grams should be possible. It will
    be used in a 2oz 30in span hand launch glider. By tilting the rudder
    ,you can trim for medium speed straight ahead,get a nice slow thermal
    turn in one direction, and a spiral dive in the opposite direction
    ,all with a single channel proportional set up. What I need to know
    is, who makes an airborn channel fm transmitter that also switches to am?
    I need a new Tx and heard that someone makes such a beast.
             In a different but similar vein I'm also involved in an
    ultrasonic control project. It uses an electeret mike into a high
    gain bandpass filter. This signal is fed to a PLL (phase locked
    loop) and runs an antique actuator by varying the tone duty cycle.
    Early experiments have been quite promising. The unit is light and
    simple and works quit well up to 400' away. I use a piezo tweeter
    as a transmitter element. It is intended for CO2 powered models
    and micro hand launch gliders.
                                    besides the notes repliesI can
                                    reached at CSS::SWEENEY
    
    
    
    
    
    
    
    
    
    
    

    Eric,
    	Is this the same Eric that used to do similar things with Slope
    Soarers at the Meon Valley Club in the UK  7 or 8 years ago.?
    
    	I've recently got back into the Notes file and have seen your
    name pop up in several "soap box" areas which seem to be too much
    of a coincidence.... it sounds like the Eric Henderson late of
    UK, MVSA and Alton... have I got the right guy????

    Sorry folks...
    	I said I was new back to notes......... forgot to sign off..
    
    Regards Trevor Hornby.
    
    		Still in the UK but now moved to Southamton area.

I got the September issue of Model Builder (nice mag.) and was impressed with 
the article that talked about using shape memory alloy wire as a "servo". For
background, this wire will shrink in length when a current is applied. This could
supply the pull in a pull/pull cable system.

My topic is "How small can we get?"

Could we make a multi channel, indoor rubber powered R/C plane with this
technology?

I always thought Multi .049 & .020 was out of reach but it is available ARF
now. I would think we could set up a reed type of system (full throw only)
and with a current limiting system maybe even proportional!

I'll throw it out to the floor for ideas.

Doggone, I remember a recent mag, within the last two months,
that talked about RC CO2 power.  I think it was done in
Czech. (can't spell that one!).  Was it Eloy Marez's column in
Model Builder?

I've mentioned this one before in this context, but in the 70's
Ken Willard published a peanut-sized .010 powered RC biplane.
Real cute too.

I've recently become interested in the "wee r/c" aspects and would like to 
contact/hear more about what people have accomplished. I'm wondering how an 
earlier replier made out with his ultralight Rx (find a Tx?) as well as 
progress with the ultrasonic idea. I'm interested in the possibility of indoor
peanut size stuff. Maybe we can laminate some components onto the spars of
a microfilm model and actually warp the surfaces with memory shape wire?

Jim HANNAH:: Reith

The November issue of Model Builder contains an article on The
Micro Albin receiver that gives construction details for an
actuator.  I haven't read it yet but it looks like good info.

        I'd be interested in a copy of this article (my mailstop is ACI)
        if you don't mind, just for historical comparison.
        
        You DON'T want to build one of these. The Albin design is a super
        regen receiver. That design might have worked in the 60's, but
        died from the mid 70's CB craze. ANY CB channel would interfere
        with them. To use them on 72MHz would require the ENTIRE band be
        clear. Not likely in todays RF environment.  The only person I
        ever saw use one of these successfully did so on the 10 meter ham
        band, in the middle of nowhere. 
        
        The design used a pulse actuator. I haven't seen these sold for
        years, since ACE dropped them from their catalog. There was a
        Mattel unit available surplus a while back, that I picked up for
        $10. I did build a couple of the Albin type actuators to work with
        that unit. They worked, but had little torque.
        
        The design is quite clever, but extremely finicky. One of the
        transistors (what! no chips?) had to be hand selected from a pile
        of them, until you found one that would work. They were hard to
        build, and harder to keep working.
        
        So much for the Albin design. The Micro-Albin was the same
        circuit, but shrunk to a .5in^2 circuit board with FOURTY
        miniature components on it. I know the guy who re-laid out the
        components. He may be the only person who ever built one and got
        it to work. He ruined his eyesight building them.
        
        Summary: Interesting history, but save your efforts.