Thunderstormer (oz9052)


Thunderstormer (oz9052) by Doug Spreng 1966 - plan thumbnail

About this Plan

Thunderstormer. Radio control pattern plane, for Veco .61 power.

Quote: "The whole thing started out as sort of a joke. Don Mathes and I decided to see how small a fuselage we could wrap around the Micro-Avionics receiver and servos. Would you believe his is skinnier.

Actually, the initial design effort goes back almost a year to just prior to last year's Nationals. My usual last minute effort produced the first Thunderstormer. It was an ambitious effort. It was designed around the Rossi engine and featured a 'flap' and flying stab. As it turned out, I should have named it 'Blunderstorrner.' On the second flight the flying stab fluttered and tore the whole tail off, rudder and all! Several nasty words and a closed throttle later it dawned on me that what was left of it was still flying! It had flipped inverted after closing the throttle and was making like a big bird. As long as I didn't try to turn it too sharp it had a very shallow glide angle, so I gently guided my new 'ailerons only' bird toward the nearest tall weeds where it came to roost without a scratch! It was then exactly one week before we were supposed to leave for the Nats. I replaced the empennage with a conventional tail, which took almost a week. So, the day before we Nat'sed it, I put a couple of flights on the silly thing just to make sure nothing else would fall off.

And, of course, a hell of a lot of good all this did 'cause during the second official Nat's flight somebody tilted the runway and my toy flew straight into it! After a good cry and a six months vacation from R/C, I somewhat reservedly, but with malice of forethought, decided to spit in the toy airplane God's eye and try - once more with feeling.

So here we are once again with a model designed around the same basic, down-to-earth, practical, scientific, non-sensical, black magic and witchcraft principles that made the Stormer (oz5794) so unsuccessful. That is, it does have a fuselage, wing, tail (non-flying type), and last but not least, a 'Lee' type engine so that I don't have to throw it off a cliff to fly. (Heights make me dizzy.) The airfoil is new (to me, that is). deBolt has been using it for years. So, to be 'original,' I used the 2% cambered version instead of the symmetrical one. It is a slightly modified NACA 652 - 215, A=0.5. How does that grab you? I eliminated the reflex at the trailing edge and, naturally, sharpened up the leading edge so it would stall quicker. It does, too, make sense. You see, instead of hanging on 'til the last glitch, then dropping like a rock on extended approaches, it simply mashes into the weeds..."

Supplementary file notes

Article pages, thanks to hlsat, JHatton.


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Thunderstormer (oz9052) by Doug Spreng 1966 - model pic


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User comments

I've lusted after this design since I first saw it published in RCM. As a member of the USAF with but two stripes on my arm, there was no way I could afford the required radio equipment. The Digicon radio set it used sold for about $1000 in 1966 non-inflated dollars. Doug Spreng and his buddy Don Mathes were the creators of that system, the first in the world that used their revolutionary servo design, instantly copied by all the other radio makers. Problems doomed the Digicon to a short commercial life but others used the servo circuit with success. The exact same system is used today in the vast majority of current servos.
DougSmith - 09/08/2017
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