New member with crazy design...

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Aircar

Banned
Joined
Feb 20, 2010
Messages
3,567
Location
Melbourne Australia
Nice rework Doggy, you would need a sponson for use in water and the amount of mass, and windage, up high is worrying --I came up with my Opal configuration after studying (and experiencing) the Lake and accepting the challenge of shaft driving a remote propeller --get the engine down low and inside and almost eliminate the thrust moment at the same time, halve the drag and noise etc . The nose plunging tendency with the wing and engine up high will be much greater than before (not that there are not high wing,motor on a stick, types eg Volmer Jensen's or Sea Bee even (high enough engine but in line with wing ) The Siai Marchetti Riviera was one of the most elegant amphibians in my view and potentially a better approach even for a direct drive.
 

Doggzilla

Well-Known Member
Joined
Jun 2, 2013
Messages
2,352
Location
Everywhere USA
Nice rework Doggy, you would need a sponson for use in water and the amount of mass, and windage, up high is worrying --I came up with my Opal configuration after studying (and experiencing) the Lake and accepting the challenge of shaft driving a remote propeller --get the engine down low and inside and almost eliminate the thrust moment at the same time, halve the drag and noise etc . The nose plunging tendency with the wing and engine up high will be much greater than before (not that there are not high wing,motor on a stick, types eg Volmer Jensen's or Sea Bee even (high enough engine but in line with wing ) The Siai Marchetti Riviera was one of the most elegant amphibians in my view and potentially a better approach even for a direct drive.
Thanks, tis just an idea to toss around. I realized it removed the sponson, but just left it that way to look clean :whistle:

What is the CG like on a converted floatplane? I figured the CG would be about the same, since a lake has the fuselage at low level...
 

Aircar

Banned
Joined
Feb 20, 2010
Messages
3,567
Location
Melbourne Australia
Floatplanes make me shudder --there was one doing passenger flights here until it flipped upside down one day .... the weight is up high but so is the drag and the wing drag on landing tends to keep the nose from diving but when going downwind that is not the case (some taxying downwind is almost unavoidable) --they are like 'airplanes on stilts' -far more so than even the usual long undercarriage set up .

the Lake had wing mounted fixed floats of course -they were wider at the bottom for better floatation and less intersection drag . Perhaps some type of double Custer channel wing(the twin prop ,one either side of the fuse ) with an internal engine and shaft drive to the props either side and having short floats off the bottom of the ducts would be a workable configuration --the ducts would reduce the length of float and shield the props from spray (might need a leading edge strake as well ) --the lower touch down speed with a Custer wing should favour the amphib use from lower hull loads ..
 

SkyClimber

Member
Joined
Dec 26, 2014
Messages
6
Location
Grass Vally CA
Hi PeetPilot,

It been a long time since your last post so I hope you are still around and working on your design. I was serching around and found your post and felt compelled to comment..
I like the original thinking of your design. As I also believe, why make the same ol' configuration as everyone else? The same ol' configuration will give you the same ol' performance. If you are going to put out the effort for a new design it might as well be original.
I see you have given up the notion of CR props to increase simplicity. That is probably a smart move as the CR props would simply ad another unknown in a new design. However, if I were you I would not give up my vision! Make it with a standard prop and make the design work, then if CR props make sense for your design, Add Them! There are techniques to reduce the influence between the two props such increasing the distance between them to a full radius, but then there may be shaft issues so...yes a good designer is important.
I disagree with some posters that a tapered outer portion of the wing adds complexity to the build. I would think that if you had a continuous taper you have to build every rib of a different size. With your design at least you have a fair amount of ribs of the same size making it easier. Also I like your wing design with a full sized inner portion for good wing area and a tapered outer portion to reduce mass and increase roll rate without sacrficing aileron area.
So stay true to your vision. There are a lot of good sources and very knowledgable people on this site so listen to them, but ultimately you will do what you need to do to create the aircraft you want. Good Luck!

P.S. There is a CR prop forum if you would like to join the disscusion.

SkyClimber
 
P

PeetPilot

Well when I posted my 'crazy design' back in 2011, I was only ever posting half a fantasy, half-serious daydream, hence the boyish silliness of my post... I sort of cringe re-reading my old stuff now. Nonetheless, some years have passed, and I find it incredible now, that the infamous and prolific aircraft designer himself, Burt Rutan, has happened to have created a design, virtually mimicking the design I posted here approx 5 years ago.

Article here;
https://www.flightglobal.com/news/articles/rutans-skigull-completes-first-flight-419581/

The configuration of the Skigull, is almost a 3d print of the daydream I had sat at my desk in Cessna 5 years ago.

I like to think of course, that perhaps Burt stumbled upon my design here, and picked it up and ran with it, the article says he started working on it back in 2014 - of course the man's a genius, so he very likely came upon it of his own accord, but boy what a compliment...
 
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