NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/rec/models/rc/2951

Text File | 1992-07-22 | 5.8 KB | 97 lines

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Path: sparky!uunet!ftpbox!mothost!white!rtsg.mot.com!svoboda
From: [e-mail] (David Svoboda)
Subject: RC plane crashes (was: Re: R/C Glider crashing!)
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Date: Wed, 22 Jul 1992 22:33:21 GMT
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All of my glider crashes have been pretty typical (well, there was the time I got
stuck with the verical member of a goalpost skewering through a wing...but anyway...)

Two spectacular power crashes that pop to mind:

1974.  Second "real" RC airplane; a Sig Kommander with a Kraft radio, Enya BB45,
beautiful white with red and blue pinstripes.  Perfect.  Second day out, we (my
father and I) are on the fifth flight of the day, and evening is quickly
approaching, we decided to take "one more for the road" (*always* a mistake, esp
if you let the plane hear you say it :-).  I took off and did some aerobatics (I
was just starting to "discover" pattern), and noticed that a white airplane at
dusk is not too optimal :-).  Well, somehow I ended up quite a ways away, and
the plane was getting a little hard to see.  I thought I was coming back, but
didn't have a good eye on the plane (and didn't have the experience to fly with
"low information").  Somehow, it got turned around, and when I saw it again,
it was going away.  Well, my dad thought he could see it better, so he took
the transmitter, but to no avail.  Keep in mind, now, that we can *hear* the
airplane just fine, it being at full throttle and all, but just can't get a
handle on what exactly it's doing.  Well, a good rule of thumb when you lose
sight of an airplane is to pull full up elevator (spreads the wings out, and
a looping airplane stays in about the same region of sky), so I took the
transmitter, and applied full up.  A few minutes had passed by now, and it
was getting really hazy.  So we had this looping airplane out there, listening
to it go "woooowwwwooooowwwwooooowwww" as it looped, catching the slightest
glimpse of it every ten seconds or so.  It seemed like this continued for a
couple of hours :-), but it was probably only one two minutes, when we heard
a distinct "crunch" at the "bottom" of one of the loops (the airplane was
*completely* invisible by this time) and the engine sound stopped.  Sinking
feeling.

We walked around until dark, in the corn field, in the woods beyond it.  No
luck.  It rained four inches that night.  My dad was able to take some time
off of work to search, for the next few days.  Finally, he called the city
police, and they sent a helicopter out to find it, which they did.  The wing
had come off, scraped off by entering deep woods at full throttle at the
bottom of a loop (ack!), and was lodged in the top of a (very tall) tree.  I
retrieved it with a fishing arrow.  The forward part of the fuse, everything
in front of the wing TE, containing the entire radio, and the engine, was
buried about a foot in the ground, with balsa confetti all around (apparently
the rest of the fuse).

We did not rebuild that airplane.  We never painted another airplane white.


1985.  While I was away at college (making sailplane-kabob :-), my
father was constantly building.  He had just completed a little airplane called
the "French Poodle", scratch built from magazine plans.  This airplane was a
tailless tandem-wing airplane, roughly modelled after the full scale "Pou de Ciel".
It looked sort of like a biplane, but instead of a lower wing and a stab, you
move the lower wing back on top of the fuselage tail, and stick the rudder on
top of it.  The forward wing pivoted for elevator control, ala a canard.
Really strange.

Now, one of the funny things about the construction of the airplane was that
the plans called for a .15 engine with the propeller on backwards.  Not a
misprint; it was specifically called for.  But they didn't say why.  So being
typical "more is better" modellers, and knowing that a backwards propeller would
just decrease the thrust, we ignored that and put the prop on normally.

Well, I have always been the "designated test pilot" of the family, so we go
out to fly the little thing.  Taxi normally, takeoff.  No problems.   My dad
had given it the recommended control throws and balance points, and he builds
good and straight, so it flew right off the board.  He said, "Try a loop,"
so, gently, I pulled it over, pretty as you please.  As it came to about a
45 degree down line at the backside of the loop, I seemed to get a glitch--a
momentary jab of down elevator, which hurtled the little thing at the ground.
Well, I was quick to get the up elevator to it, and a moment later it pulled out.
"Thump, thump, thump," went my heart.  "Well, we had better think about ending
this flight, and see if we have some radio problems," I said.  I make a
point always to stall an airplane once before landing the first time, so I
come across the field and did it, and the little plane just mushed nice and
straight; beautiful.  So I pushed the nose over and add throttle, and when some
speed builds, pull up, Pull Up, PULL UP.  No response, and the little airplane
just accelerated straight down from a couple hundred feet.  I chopped the
throttle just before it hit, but managed to plonk it on the runway, for a
total loss, and a sizeable hole in an asphalt runway.  Another balsa confetti mess.

Turns out (I found out later in aero school) that tandem wing airplanes, especially
the historic Pou de Ciel, tend towards a serious "tuck" problem, and at some critical
speed, cease to respond to elevator input.  The backwards prop was in effort to keep
the speed down.  The little airplane, though strong enough for it, was not meant ever
to do aerobatics.  Live and learn.

        Dave Svoboda, Palatine, IL