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Old Jun 09, 2008, 01:40 PM
Tim Wescott
Guest
n/a Posts
Curiosity: How Light is your Cub?

I'm contemplating building a model of the Aeronca LA, LB or LC. This
critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less a
Cub pretending to be a low-wing sport plane.

I'd be putting an OS MAX .25 in it, or an equivalent electric motor.
For scale-like slow flying, I keep circling back to a 1/6 scale, 4-5
pound aircraft with a 6' wingspan (and about 4 square feet of wing
area). This seems BIG for a .25, yet I know that the SIG 1/6 scale cub
comes with a recommended .25-.40 engine range -- and there's something
silly about a Cub model flying rings around a big heavy P-51.

So, what Cub (or other light plane) models have you flown, how big were
they, how heavy were they, what engine did you use, and (most important)
how did you like flying the thing?

Thanks in advance.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Old Jun 09, 2008, 03:21 PM
Ed Cregger
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?


"Tim Wescott" <tim@seemywebsite.com> wrote in message
news:UKCdndJpc4-55NDVnZ2dnUVZ_orinZ2d@web-ster.com...
> I'm contemplating building a model of the Aeronca LA, LB or LC. This
> critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less a
> Cub pretending to be a low-wing sport plane.
>
> I'd be putting an OS MAX .25 in it, or an equivalent electric motor. For
> scale-like slow flying, I keep circling back to a 1/6 scale, 4-5 pound
> aircraft with a 6' wingspan (and about 4 square feet of wing area). This
> seems BIG for a .25, yet I know that the SIG 1/6 scale cub comes with a
> recommended .25-.40 engine range -- and there's something silly about a
> Cub model flying rings around a big heavy P-51.
>
> So, what Cub (or other light plane) models have you flown, how big were
> they, how heavy were they, what engine did you use, and (most important)
> how did you like flying the thing?
>
> Thanks in advance.
>
> --
>
> Tim Wescott



Your proposed model sounds just right for a .40 four-stroke/.25 two-stroke.

I flew the old M.E.N. Trainer 20 for a while in the early Eighties. It was
first powered by a Fox .19 R/C engine that went through connecting rods like
I go through popcorn. It was the old plain bearing version. It had plenty of
power and would even R.O.G. I then switched to a Super Tigre G20/15, just
for kicks. Had to hand launch it then, but once airborne it flew just fine.
Replaced that engine with a direct bolt-in ST G21/23. Oddly enough, it flew
identically to the ST G20/15. No improvement whatsoever.

Used to fly an original kit built Falcon 56 with a Fox .25. Later went to an
OS .35 so it would take off without a hand launch. I liked the .35 much
better, even though it was throttled back to just a couple of clicks above
idle most of the time while flying.

One of the most fun models I've ever flown with a .28 - .32 sized engine was
the Florio Stunt Wagon. Yeah, you could raise hell with it, but you could
also throttle back and relax with it (750 square inches of wing area @ 4
lbs.). Put the surfaces on low rate and you could teach a newbie how to fly
with it - 4" chord ailerons and all. An amazingly fun model to fly for just
about any occasion. It wouldn't have been too difficult to do it up in
1930's blue and yellow color scheme and the big round Army Air Corps
insignias on the wing, just to give it a legitimate scalish look.

Now you have me thinking of building another Stunt Wagon. I really miss that
model. It would fit whatever mood I was in when I finally arrived at the
field. It would do outstanding maneuvers low to the ground, or you could
shoot touch and goes all day long using just throttle and rudder for
control, once trimmed. I think I have one of those kits downstairs. Pardon
me while I go rummaging...<G>


Ed Cregger


Old Jun 09, 2008, 04:52 PM
The Natural Philosopher
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?

Tim Wescott wrote:
> I'm contemplating building a model of the Aeronca LA, LB or LC. This
> critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less a
> Cub pretending to be a low-wing sport plane.
>
> I'd be putting an OS MAX .25 in it, or an equivalent electric motor. For
> scale-like slow flying, I keep circling back to a 1/6 scale, 4-5 pound
> aircraft with a 6' wingspan (and about 4 square feet of wing area).
> This seems BIG for a .25, yet I know that the SIG 1/6 scale cub comes
> with a recommended .25-.40 engine range -- and there's something silly
> about a Cub model flying rings around a big heavy P-51.
>
> So, what Cub (or other light plane) models have you flown, how big were
> they, how heavy were they, what engine did you use, and (most important)
> how did you like flying the thing?
>


plenty of 5 footers flying on 150W or less. About 2cc or a 0.15 in old
money.

5lb would need at most 250W at teh right prop to fly well..that's about
a .20

I don't do gassers but thats where an opverpropped 30-36 4 cycle would
seem to be perfect.


> Thanks in advance.
>

Old Jun 09, 2008, 05:09 PM
Tim Wescott
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?

The Natural Philosopher wrote:
> Tim Wescott wrote:
>> I'm contemplating building a model of the Aeronca LA, LB or LC. This
>> critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less
>> a Cub pretending to be a low-wing sport plane.
>>
>> I'd be putting an OS MAX .25 in it, or an equivalent electric motor.
>> For scale-like slow flying, I keep circling back to a 1/6 scale, 4-5
>> pound aircraft with a 6' wingspan (and about 4 square feet of wing
>> area). This seems BIG for a .25, yet I know that the SIG 1/6 scale
>> cub comes with a recommended .25-.40 engine range -- and there's
>> something silly about a Cub model flying rings around a big heavy P-51.
>>
>> So, what Cub (or other light plane) models have you flown, how big
>> were they, how heavy were they, what engine did you use, and (most
>> important) how did you like flying the thing?
>>

>
> plenty of 5 footers flying on 150W or less. About 2cc or a 0.15 in old
> money.
>
> 5lb would need at most 250W at teh right prop to fly well..that's about
> a .20
>
> I don't do gassers but thats where an opverpropped 30-36 4 cycle would
> seem to be perfect.
>

If I were to go up in displacement it would be so I could swing a larger
prop -- scale size would be 12 or 13", while the engine I have 'wants' a
10x4 or 9x5, and may not have the oomph if I sacrificed some power to
the Big Propeller Gods.

Or I may go electric -- it's just that I keep winning these gallons of
fuel at the club raffle, and a .25 doesn't use much, particularly since
I don't fly a whole bunch.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Old Jun 09, 2008, 05:12 PM
Robert Reynolds
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?

http://www.rcmmagazine.com/store/sto...LljtMg7g49W9P1)
That's the link to the Terrier, from the RCM plans catalog, 58" span,
550 sq. in., .25 engine. That's pretty close to what you're talking
about, except your aspect ratio will be higher.

I built a couple of Terriers a few years ago and sold one to a friend.
He powered his with an OS 40 LA, and I put a 40 Surpass on mine.
Performance was very good, with decent vertical and good speed. Also
low speed performance was excellent.

I would expect a .25 to do the trick for a plane this size, but you
would have to choose the right propeller for the desired performance.
Essentially you would have to drive around in first gear and sacrifice
high speed performance, because the plane wouldn't be capable of going
fast anyway, unless you put a 40 on it. Try a .25 and a 10x4 to start with.



Tim Wescott wrote:

> I'm contemplating building a model of the Aeronca LA, LB or LC. This
> critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less a
> Cub pretending to be a low-wing sport plane.
>
> I'd be putting an OS MAX .25 in it, or an equivalent electric motor. For
> scale-like slow flying, I keep circling back to a 1/6 scale, 4-5 pound
> aircraft with a 6' wingspan (and about 4 square feet of wing area).
> This seems BIG for a .25, yet I know that the SIG 1/6 scale cub comes
> with a recommended .25-.40 engine range -- and there's something silly
> about a Cub model flying rings around a big heavy P-51.
>
> So, what Cub (or other light plane) models have you flown, how big were
> they, how heavy were they, what engine did you use, and (most important)
> how did you like flying the thing?
>
> Thanks in advance.
>

Old Jun 09, 2008, 05:55 PM
Mark
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?

On Mon, 09 Jun 2008 11:40:47 -0700, Tim Wescott wrote:

> I'd be putting an OS MAX .25 in it, or an equivalent electric motor. For
> scale-like slow flying, I keep circling back to a 1/6 scale, 4-5 pound
> aircraft with a 6' wingspan (and about 4 square feet of wing area).
> This seems BIG for a .25, yet I know that the SIG 1/6 scale cub comes
> with a recommended .25-.40 engine range -- and there's something silly
> about a Cub model flying rings around a big heavy P-51.
>
> So, what Cub (or other light plane) models have you flown, how big were
> they, how heavy were they, what engine did you use, and (most important)
> how did you like flying the thing?
>
> Thanks in advance.


I had a 7' old timer ("Ol' Reliable") that weighed in at just under 4 lb
(wet) with about 6 sq ft of wing area. It had an OS .25FP, which is
about as wimpy as .25s get, and the problem was *landing* - I had the
idle a little high, and the thing would just putter along in ground
effect for the whole length of the field. If there wasn't a headwind, I
usually had to shut off the engine to get it to land.

It would do these beautiful hands-off takeoffs at about 1/3 throttle -
I'd set 1/3 throttle, put the tx down, let go of the tail . . . I sure
miss that plane.

Anyway, if you build it light, aren't looking for aerobatics, and build
it light, a .25 should be fine, as long as the plane is light.

- Mark

P.S. build it light. For example, if it's 3 channels, a 'standard' radio
with 3 std servos, 500 mah nicad, switch, and big rx will weigh about 10
oz. A small rx (say, a Berg or Spektrum) with 3 HS81s, small switch, and
a NiMH battery will weigh under 5 oz. That's 1/3 of a pound savings right
there.
Old Jun 10, 2008, 07:21 AM
Dave Plumpe
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?

Tim-
I have a 71" SIG 1/6 Cub with about 225 flights on a OS FS26 4-stroke.
http://plumpe.home.mindspring.com/mair.html
3.75 lbs with silk & dope covering (about same weight as Monokote), GWS mini
servos (about 1/2oz lighter than standard servos), standard Futaba rcvr &
battery. Flies great, even on floats! Most flying is at 1/2 throttle, but
I use full throttle for takeoff & getting out of binds. I'd like to try an
OS FS20, but the 20 is not as tall and I'd have to cut the cowl some to
clear the exhaust - and I don't think the FS20 would be a good choice for
floats.

If I were to use a 2-stroke, I'd go with a .20 or mild .25. I'd save a .40
2-stroke for the FJ-3, the fighter version of the Cub.

-Dave

"Tim Wescott" <tim@seemywebsite.com> wrote in message
news:UKCdndJpc4-55NDVnZ2dnUVZ_orinZ2d@web-ster.com...
> I'm contemplating building a model of the Aeronca LA, LB or LC. This
> critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less a
> Cub pretending to be a low-wing sport plane.
>
> I'd be putting an OS MAX .25 in it, or an equivalent electric motor. For
> scale-like slow flying, I keep circling back to a 1/6 scale, 4-5 pound
> aircraft with a 6' wingspan (and about 4 square feet of wing area). This
> seems BIG for a .25, yet I know that the SIG 1/6 scale cub comes with a
> recommended .25-.40 engine range -- and there's something silly about a
> Cub model flying rings around a big heavy P-51.
>
> So, what Cub (or other light plane) models have you flown, how big were
> they, how heavy were they, what engine did you use, and (most important)
> how did you like flying the thing?
>
> Thanks in advance.
>
> Tim Wescott



Old Jun 10, 2008, 08:00 AM
Six_O'Clock_High
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?


"Dave Plumpe" <lastname@mindspring.com> wrote in message
news:27OdnYkuRqIy7NPVnZ2dnUVZ_qHinZ2d@earthlink.co m...
>
> If I were to use a 2-stroke, I'd go with a .20 or mild .25. I'd save a
> .40 2-stroke for the FJ-3, the fighter version of the Cub.
>
> -Dave



WHAT????

"fighter version of the Cub"!!!!!!!!!!!!

I almost choked on my coffee over this one.


Old Jun 10, 2008, 12:01 PM
Tim Wescott
Guest
n/a Posts
Re: Curiosity: How Light is your Cub?

Dave Plumpe wrote:
(top posting fixed)
>
> "Tim Wescott" <tim@seemywebsite.com> wrote in message
> news:UKCdndJpc4-55NDVnZ2dnUVZ_orinZ2d@web-ster.com...
>> I'm contemplating building a model of the Aeronca LA, LB or LC. This
>> critter has a 9:1 aspect ratio and a 70HP engine, so it's more or less a
>> Cub pretending to be a low-wing sport plane.
>>
>> I'd be putting an OS MAX .25 in it, or an equivalent electric motor. For
>> scale-like slow flying, I keep circling back to a 1/6 scale, 4-5 pound
>> aircraft with a 6' wingspan (and about 4 square feet of wing area). This
>> seems BIG for a .25, yet I know that the SIG 1/6 scale cub comes with a
>> recommended .25-.40 engine range -- and there's something silly about a
>> Cub model flying rings around a big heavy P-51.
>>
>> So, what Cub (or other light plane) models have you flown, how big were
>> they, how heavy were they, what engine did you use, and (most important)
>> how did you like flying the thing?
>>
>> Thanks in advance.
>>
>> Tim Wescott

>
> Tim-
> I have a 71" SIG 1/6 Cub with about 225 flights on a OS FS26 4-stroke.
> http://plumpe.home.mindspring.com/mair.html
> 3.75 lbs with silk & dope covering (about same weight as Monokote), GWS mini
> servos (about 1/2oz lighter than standard servos), standard Futaba rcvr &
> battery. Flies great, even on floats! Most flying is at 1/2 throttle, but
> I use full throttle for takeoff & getting out of binds. I'd like to try an
> OS FS20, but the 20 is not as tall and I'd have to cut the cowl some to
> clear the exhaust - and I don't think the FS20 would be a good choice for
> floats.
>
> If I were to use a 2-stroke, I'd go with a .20 or mild .25. I'd save a .40
> 2-stroke for the FJ-3, the fighter version of the Cub.
>
> -Dave
>

The OS-Max (pre- LA, FP, QX, whatever) is definitely a mild engine.
It's just a plain-bearing loop-scavanged, cast-iron in steel sport engine.

So I think I'm set.

FJ-3 -- I like that. I've seen a few of them. When you have to sheet
the wings against flutter, then you know the engine's too big...

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
 


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