Very low aspect ratio planes?

[Starman]

In my drawing the pilots eyes are close to the leading edge of the wing, so he can look almost straight down (of course to the side a little bit) and by moving his head forward a couple of inches the pilot can look straight down. Also there is only a gearbox in front of the pilot's feet, not a whole engine so the visibility ahead is much better too. It's like being in a sailplane. Also, the fuselage is directly in front of the fat wing for much less frontal area. Your design has a 'house' on top, which is not nearly as aerodynamically efficient. The Arup type wings also blocks your view downwards 100%.

So, should I say it? My design is much better =)

 

[Sockmonkey]

I wouldn't go tailless for this or a taper ratio any smaller than 0.5 with a straight leading edge. The empenage should be far enough back that the wing does not interfere with the vertical fin too much. The stabilizer should be fairly low so it can do its job when the wing is stalled. The wing should be set at a pretty high incidence too and since it's such a short coupled little beast the airfoil should be as close to Cm0=0 as possible.

I would like to stick with tailless if possible for the sake of simplicity and structual strength if possible, so yeah I'll have to move some stuff around.
Maybe go with a delta wing like an upside-down version of the verheese delta.

At each wing tip there is a 0.6 Kg battery, a .24kg motor, plus controller, plus retractable gear and the fuselage weight itself. At high speeds is stable as a rock and highly manoeuvrable for its moving surfaces range (I like them agile) , but at low speeds there must be some fence effect also by the fuselages. In any case the funny thing is that it doesn't flip upside down as I thought it would in the first flight, but flies in some funny manner hence the air bubble feeling. Big inertia forces are not enough, It surprised me that aerodynamic forces can counteract them at any regime. You've sparked a new plan for this victim btw so as soon as I clear my work I'll make some changes.

At some point I'd try sticking all-flying nub fins outboard of the nacelles just behind the props to see what kind of maneuvering tricks you could pull off.

You could do those things ... if you want a big old stinky old engine blocking your view ahead, and a big fat wing blocking your view downwards, and poor control response. You could easily achieve those improvements. Oh yes, it also looks way ugly. Sorry, I don't do ugly, unresponsive, or poor visibility.

Well, pulling the center bit back doesn't restrict visibility much if it's still using the center body engine and shaft-driven prop. You could try a version of the hatfield little bird with that engine setup or go extra crazy with a high-winged version of the arup.

There's all your visibility problems solved.

 

[Norman]

There's all your visibility problems solved.

I don't think so. If you make the skin above the cockpit transparent you'll have some upward visibility but the wing still blocks most of the upward view. The blades of a spinning prop count as fins whether the power is on or not so puting it up front makes it necessary to increase the size of the vertical fin. A pusher prop allows you to get the pilot's eyes up front, where they belong, and it increases stability a little bit. If the airfoil is fairly thick you could put the pilot's head inside the wing behind a transparent leading edge.

 

[Sockmonkey]

I don't think so. If you make the skin above the cockpit transparent you'll have some upward visibility but the wing still blocks most of the upward view. The blades of a spinning prop count as fins whether the power is on or not so puting it up front makes it necessary to increase the size of the vertical fin. A pusher prop allows you to get the pilot's eyes up front, where they belong, and it increases stability a little bit. If the airfoil is fairly thick you could put the pilot's head inside the wing behind a transparent leading edge.

Increasing the size of the vertical fin is perfectly acceptable. As for upward visibility, a small transparent panel could be added to the wing on either side of the engine.
Really, I'm more concerned with side and downward visibility as those are most critical for landing. Particularly if you want a high AOA STOL.

 

[Topaz]

... Particularly if you want a high AOA STOL.

If you want a STOL airplane, tailless is a very poor choice. Tailless is at its finest for a high-thrust-loading cruising airplane. STOL requires maximum possible lift coefficient across the entire span at takeoff or landing and, in a tailless airplane, your pitch control surfaces are going to ruin that plan simply by using them.

 

[Sockmonkey]

If you want a STOL airplane, tailless is a very poor choice. Tailless is at its finest for a high-thrust-loading cruising airplane. STOL requires maximum possible lift coefficient across the entire span at takeoff or landing and, in a tailless airplane, your pitch control surfaces are going to ruin that plan simply by using them.

That was in reference to airplanes with poor upwards visibility in general, but yeah you really can't do STOL with this one.
High AOA takeoff and landing is doable though.

 

[Topaz]

... High AOA takeoff and landing is doable though.

Do you see some particular advantage in doing so?

 

[WonderousMountain]

Pretty useful technique for reducing landing speed.

 

[Sockmonkey]

Made some tweaks to make it more sexy and added more rudder.

 

[Topaz]

Pretty useful technique for reducing landing speed.

True, except that you're "committed" at that stage. Well on the back side of the power curve. Doesn't give the pilot a lot of options if, for example, hit with a sharp gust late in the process.

 

[BJC]

Hig alpha landing https://m.youtube.com/watch?v=Ejbv7U6kgyw

High alpha crash https://m.youtube.com/watch?v=zD3fdKmMdQM


BJC

 

[henryk]

Hig alpha landing https://m.youtube.com/watch?v=Ejbv7U6kgyw

High alpha crash https://m.youtube.com/watch?v=zD3fdKmMdQM


BJC

-and LOW AoA take offs/landings...\vortex generators !\

https://www.youtube.com/watch?v=MIMPXr_VgNo

 

[cluttonfred]

BJC, henryk, what do these clips of heavy, jet-powered take-offs, landings, and crashes have to do with low aspect ratio light aircraft?

I don't see these as any more relevant than radio-controlled flying lawn mowers or other RC examples that simply show that with high power and low weight you can make almost anything fly.

Arup, Zimmerman, Hoffman, Eshelman, Vought V-173, etc. are relevant to light aircraft discussions in terms of wing and power loadings, but the clips you posted don't really provide much useful information for light aircraft.

 

[henryk]

-see "vortex augmented lift"...

 

[erkki67]

We are approaching the concept of the flying horseshoe of the Arup design

It had an engine up in front, but it was a simple direct drive, with good flying characteristics.
I'm wondering what banned Topspeed100 would have come up with for a LAR plane!
Rki

 

[Doggzilla]

We are approaching the concept of the flying horseshoe of the Arup design
View attachment 43509
It had an engine up in front, but it was a simple direct drive, with good flying characteristics.
I'm wondering what banned Topspeed100 would have come up with for a LAR plane!
Rki

I was actually sitting in my truck looking out at the sky a few months ago waiting for a few hours, and realized that some of Topspeed's ideas were actually feasible if he wasnt trying to power them by 300 obese tourists.

It wasnt that the designs were bad, it was that he was considering the wrong materials, and the wrong goals. And I dont mean he needed to use titanium with spider silk, he was actually using too stiff of materials.

 

[BJC]

BJC, henryk, what do these clips of heavy, jet-powered take-offs, landings, and crashes have to do with low aspect ratio light aircraft?

I don't see these as any more relevant than radio-controlled flying lawn mowers or other RC examples that simply show that with high power and low weight you can make almost anything fly.

Arup, Zimmerman, Hoffman, Eshelman, Vought V-173, etc. are relevant to light aircraft discussions in terms of wing and power loadings, but the clips you posted don't really provide much useful information for light aircraft.

Matthew:

Responding to the comments about high alpha landings. The aerodynamics that lead to high alpha landings for the Concorde, a fine example of a low aspect ratio airplane, would also apply to a low AR light plane.

There was also a comment about getting behind the power curve at high alpha. The second link showed an example of that.

Thanks for asking.


BJC

 

[Sockmonkey]

We are approaching the concept of the flying horseshoe of the Arup design
View attachment 43509
It had an engine up in front, but it was a simple direct drive, with good flying characteristics.

Yep, that's exactly what I'm getting at, only with a high wing.

 

[WonderousMountain]

AR 2.712 , I measured the semispan in eights, and the semichord as 20ths. If you look closely you'll see the rib positions.

 

[WonderousMountain]

Drew in a potential substructure. I like it a good bit. fits the many pieces theme without becoming too messy.

LuPi