| Re: .-1,
Well, yer' givin' me a tailor-made opportunity to air some of my
favorite beliefs/prejudices with this one.
1.) Little airplanes do not fly...they FLIT! The smaller the
airplane, the harder to fly; it has to do with Reynolds-numbers being
too high and, perhaps most importantly, wing-loadings that are way too
high. This occurs simply as a matter lack of building materials which
are sufficiently light to produce a suitably light but strong structure
for flying purposes. For example, if metals were the only material
available to us, then the smaller the model, the proportionately
heavier it'd be as we go down in size. The Guillow's models are
already a bit weighty (due to all the plastic scale details) for good
flight under rubber-power alone...now add engine, radio, batteries,
etc. and you have an undesireably high wing loading.
2.) The Stuka had a high-aspect wing, i.e. it was highly double-tapered,
producing a very narrow chord at the tip and this condition is custom
made for tip-stalls, *especially*if*the*wing*loading*is*high*. There
just isn't a whole lot that you van do about this except to reduce
weight (vis-a-vis wing loading) as much as possible. About the only other
thing you can do is build 2-to-3 degrees of washout into the wingtips.
This will help to prevent the tips from stalling 'til _after_ the
center-section has stalled.
3.) With all that taken into consideration, I wouldn't even _attempt_
this airplane without ailerons! At its very best, the plane'll be
squirrely enough that it'll REQUIRE all the control authority you can
get. Rudder and elevator only are fine for high-wing, floaty kind'a
planes (like J-3 Cubs, Aeronca Champs, etc.) but this doesn't provide
the control necessary for a project such as yer's.
4.) In order to enhance their marketability, makers of rubber-powered
kits (like Guillows, Sterling, Comet, etc.) are quick to add the phrase
"Can Be Radio-Controlled" to their kit boxes. And this is not entirely
untrue but they fail to tell the unsuspecting modeler (usually a beginner)
that accomplishing R/C flight will require LOTS'A skill, cunning and
moxy which is the domain of the highly experienced modeler. The small,
light, all-foam ARF [so-called] trainers from Testors (and others) are
a REAL challenge for an experienced modeler to get to fly so how can we
possibly expect that an even smaller, more heavily wing loaded plane
has any better chance to succeed?!!
5.) But, it _can_ be done. A friend from California, Buzzy Watson, has
made a thing of bringing an even more spectacular LITTLE airplane to
our 1/8 AF Scale Fly-In's every Spring. He's had a Guillows SBD
Dauntless, complete with operating dive flaps and bomb release in
addition to full flight and engine controls AND retractable landing
gear. Last year and this year he brought a Guillows P-47 Thunderbolt,
again full-house PLUS retracts. Buzzy fully sheets these models and
beefs them up to withstand the rigors of R/C...usually powers them with
an O.S. .10 with throttle. And they DO fly! However, Buzzy, a _very_
accomplished pilot himself, leaves the flying duties to Jerry Kitchen,
considered to be the hottest stick on the west coast, and Jerry has his
hands REAL full with these little beasties! I can tell you that _I_
have no interest whatever in being humiliated by one of 'em! :B^)
My advice is (and always has been) to go with the largest airplane yer'
budget and/or building space can accomodate...they simply fly better,
the bigger they are. Conversely, there is a point of diminishing
returns as scale goes down, beyond which success is unlikely.
__
| | / |\
\|/ |______|__(o/--/ | \
| | 00 <| ~~~ ____ 04 ---- | --------------------
|_|_| (O>o |\)____/___|\_____|_/ Adios amigos, Al
| \__(O_\_ | |___/ o (The Desert Rat)
|
| RE: Note 1228.1 by UPWARD::CASEYA "THE DESERT RAT (I-RC-AV8) 551-5572"
>> 1.) Little airplanes do not fly...they FLIT! The smaller the
>> airplane, the harder to fly; it has to do with Reynolds-numbers being
>> too high and, perhaps most importantly, wing-loadings that are way too
>> high.
Al, I have to agree with everything you've said, except one teeny
tiny nit-pick which was probably just a slip-up on your part.
As the chord of the wing gets smaller and/or airspeed goes down, so
does the Reynolds number. Reynolds number is defined as:
Re = k * chord * airspeed
where k is a constant dependent on the units used for chord and
airspeed.
So, for small models, the Reynolds number is too SMALL.
Other than this little typo, I have to agree with most (or maybe
even all) of what you've said...
_____
| \
| \ Silent POWER!
_ ___________ _________ | Happy Landings!
| \ | | | | |
|--------|- SANYO + ]-| ASTRO |--| - Dan Miner
|_/ |___________| |_________| |
| / | " The Earth needs more OZONE,
| / not Caster Oil!! "
|_____/
|
| Gracias fer' the correction, Dan'l. I was never real sure about
Reynolds number and how it affects models except to know that it was
too one-way-or-the-other for models to fly as well as the prototypes
and the situation gets worse the smaller the model gets. The statement
that big models fly better is more than a statement of prejudice by the
giant scale guys, IT IS ABSOLUTE FACT!
For example, the itty-bitty Pee-47 I described in .2 challenges even
the most skilled R/C pilots to get it up and down in one piece, the
.20-size standoff version designed by Rich Uravitch as a companion to
the little AT-6 that many clubs have pylon races with is better but can
be treacherous of any pilot error, the .40-powered JEMCO P-47 is better
but remains pretty skittish, the .60-.90 powered Holman Jug is pretty
honest and the 80" Baker Jug with Webra Bully, Quadra-50, etc. flies like
a baby carriage, completely stable and friendly, even forgiving of some
pretty ham-fisted pilotage. I rest my case.......
__
| | / |\
\|/ |______|__(o/--/ | \
| | 00 <| ~~~ ____ 04 ---- | --------------------
|_|_| (O>o |\)____/___|\_____|_/ Adios amigos, Al
| \__(O_\_ | |___/ o (The Desert Rat)
|
| THANKS GUYS, YOUR INFO SURE MAKES A LOT OF SENSE. I AM NEW TO THIS
SPORT (2'ND YEAR) I'M SORRY I SORTA FELL IN LOVE WITH THE LOOK
OF THE STUKA. I PRESENTLY FLY A 42" COWBOY, 52" SCOUT 15 AND A
GENTLE LADY WITH A 9 FOOT WING AND ELECTRIC POWER. AS YOU CAN SEE
I'M MORE ACCUSTUMED TO SOME PRETTY TAME MODELS. I DID HAVE A LITTLE
ALFA (34" WING I THINK) WITH AN OS .10. IT WAS FUN UNTIL THE WING
SNAPPED ABOUT 200FT. UP. THE GREEN PLASTIC BAG CAME IN HANDY.
ANYHOW, JUST TO BE STUBBORN, IF THE MODEL WAS SCALED UP TO SAY 60-
70 INCH WING ,WITH FOUR CHANNELS, WOULD IT BE WORTH THE EFFORT OR
IS THIS STYLE OF PLANE JUST TOO HAIRY TO CONTROL ? I WONDER BECAUSE
I FAIL TO FIND ANY, OTHER THAN THIS GUILLOWS KIT, IN HOBBY SHOPS OR
MAGAZINES.
THANKS AGAIN
MR.
BILL OH NO
O
O
O
|
| RE: .-1,
As in the example I gave of the various sized P-47s, yes, the Stuka
becomes a more viable project the larger it gets. It remains, however,
a bit treacherous in ground handling owing to the stiff, narrow landing
gear and still demands that you avoid low, slow, nose-high attitudes (just
as the real one did).
To my knowledge, there are no kits for Stukas in any reasonable size
but Bob Holman sells plans, canopy, etc. for one of ~65" span for
.60-to-.90 power. Bob Francis of northern Callifornia flies a quite
large Stuka (I'm guessing ~85" span) and does a very nice job with it.
Billy Hemple of Tucson flew an enormous Ju-87 at the last Top Gun...it
spanned (I think) 118" and was equipped with an onboard electric siren
which was switched on in the dive bombing run to simulate the air
driven sirens the Stuka was equipped with for psychological effect.
I should mention that both of these gentlemen are very experienced
pilots and the Stuka's landing gear still trips them up on occasion.
The big ugly bird from Junkers is not for the inexperienced or the
faint of heart...do yer' homework and get plenty of experience before
attempting it.
__
| | / |\
\|/ |______|__(o/--/ | \
| | 00 <| ~~~ ____ 04 ---- | --------------------
|_|_| (O>o |\)____/___|\_____|_/ Adios amigos, Al
| \__(O_\_ | |___/ o (The Desert Rat)
|