Flyability of Biplane Flying Boat

[durabol[_2_]]

I have been working on a biplane flying boat (similar to some in the
early 1900s). Rough weight estimates are: fuselage/tail/controls 200,
Rotax 503/5Gal fuel 150, wings 150, me 225 = 725 gross. The reason for
the biplane configuration is for the large wing area (250sq.ft) I feel
will be needed to get off the water. Any opinion on whether this will
work? Perhaps I could get by with less wing area? I would also like
tandem seating if the design can handle the extra weight.

Brock

[Ron Wanttaja[_2_]]

On 1/26/2011 1:32 AM, durabol wrote:
> I have been working on a biplane flying boat (similar to some in the
> early 1900s). Rough weight estimates are: fuselage/tail/controls 200,
> Rotax 503/5Gal fuel 150, wings 150, me 225 = 725 gross. The reason for
> the biplane configuration is for the large wing area (250sq.ft) I feel
> will be needed to get off the water. Any opinion on whether this will
> work? Perhaps I could get by with less wing area? I would also like
> tandem seating if the design can handle the extra weight.

Probably could get by with less wing area. Fly Babies have 120 square
feet of wing, and the 65-HP prototype did fly with floats. Roughly
1,000 pounds gross. A company called Two Wings Aviation had a biplane
flying boat a number of years back, powered by a Rotax two-stroke.

http://www.lightsportaircraftpilot.com/mariner_lightsportaircraft/

It had the same span as a Fly Baby, probably slightly less chord, but of
course two wings. Probably ~175-200 sq ft.

However, the devil is in the details. The hydrodynamics of the hull are
going to be vital, and selecting a prop that'll let the plane get off
the water quickly yet still offer some cruise speed will be involved.

Ron Wanttaja

[jan olieslagers[_2_]]

Op 26/01/2011 09:32, durabol schreef:
> I have been working on a biplane flying boat (similar to some in the
> early 1900s). Rough weight estimates are: fuselage/tail/controls 200,
> Rotax 503/5Gal fuel 150, wings 150, me 225 = 725 gross. The reason for
> the biplane configuration is for the large wing area (250sq.ft) I feel
> will be needed to get off the water. Any opinion on whether this will
> work? Perhaps I could get by with less wing area? I would also like
> tandem seating if the design can handle the extra weight.
>

I can't help telling you to calculate the wing area you want rather than
feeling it, sorry if that sounds rude.
Also I seem to understand taking off from water will merely require a
longer run to reach lift-off speed, but then the very reason for taking
off from water is the availability of long straight flat areas of it.

Compared to a "conventional" aircraft, a hydroplane has more drag; that
requires more engine power to counter, not more wing surface.

BTW you left me in a bit of doubt about how to interpret your figures:
are your weights lbs or kgs? But I think it may be assumed you are
US'an, and talking feet and pounds.

[durabol[_2_]]

-Thanks for the information.

-The Mariner is very similar to what I had envisioned.

-I will probably reduce the wing area to a bit under 200sq.ft (a bit
more manageable size wise and better in the wind)

-I will probably go with a "climb" prop. to get off the water, cruise
speed isn't a concern as I just plan to fly it for fun. I have a fair
amount of information on seaplane hulls so hopefully I can just use
typical dimensions.

-For wing design I had thought about making as large a wing as
practical for as low a take off speed as possible, as I thought this
would give the best odds of getting off the water.

-Yes I was using lbs. I'm actually Canadian and we are officially
metric but because the US refuses to adapt we have to learn both. They
really messed me up in that for temperature I use Celsius when it is
cold and Fahrenheit when it is warm. :)

Brock

[rckchp]

I can't recall the particulars, but I remember seeing a biplane flying
boat at Sun n Fun years ago. It actually was an aluminum boat (I think
it was a 14' jon boat) with a set of biplane wings grafted on... I
think with a tail boom mounted empanage. I also think it had
retractible wheels for land ops. Maybe some other reader can add
details?

On Jan 26, 4:32*am, durabol > wrote:
> I have been working on a biplane flying boat (similar to some in the
> early 1900s). Rough weight estimates are: fuselage/tail/controls 200,
> Rotax 503/5Gal fuel 150, wings 150, me 225 = 725 gross. The reason for
> the biplane configuration is for the large wing area (250sq.ft) I feel
> will be needed to get off the water. Any opinion on whether this will
> work? Perhaps I could get by with less wing area? I would also like
> tandem seating if the design can handle the extra weight.
>
> Brock

[[email protected]]

On Tue, 1 Feb 2011 10:08:22 -0800 (PST), rckchp >
wrote:

>I can't recall the particulars, but I remember seeing a biplane flying
>boat at Sun n Fun years ago. It actually was an aluminum boat (I think
>it was a 14' jon boat) with a set of biplane wings grafted on... I
>think with a tail boom mounted empanage. I also think it had
>retractible wheels for land ops. Maybe some other reader can add
>details?
>
IIRC it was setting in a puddle of water.

[Scott Perkins]

On Wednesday, January 26, 2011 at 4:32:09 AM UTC-5, durabol wrote:
> I have been working on a biplane flying boat (similar to some in the
> early 1900s). Rough weight estimates are: fuselage/tail/controls 200,
> Rotax 503/5Gal fuel 150, wings 150, me 225 = 725 gross. The reason for
> the biplane configuration is for the large wing area (250sq.ft) I feel
> will be needed to get off the water. Any opinion on whether this will
> work? Perhaps I could get by with less wing area? I would also like
> tandem seating if the design can handle the extra weight.
>
> Brock

There are many examples of which you describe and much seaplane design
info at a yahoo group called SEABUILD. The size of the wings or the
"wingloading" mostly dictates how fast you want to fly and crash
assuming you have designed for enough thrust to get you to the speed
necessary for flying. Although biplanes disappeared due to poor
efficiency in favor of monoplanes there are a couple of good reasons
for their use in seaplanes. Mainly they are good to mount sponsons
on the lower wings while avoiding the dangerous massive pitch forward
tendencies of pure low wing monowing seaplanes.