3Dlight aircraft concepts

colbmista

got bored so i did some low poly air craft designs the 2 on the right are pretty much the same on the left but the wings are swept forward a bit they are single seat aircraft what do you all think what set up should i work on more

colbmista

some other angles

aircraft2.jpg
aircraft3.jpg
aircraft4.jpg

colbmista

well i decided on the slight forward swept design with the tail fins down and here is what i have so faraircraft5.jpg

Stonecold

Wouldn`t it be unstable with wings inclined down? Still, good looking design!

Knight26

It is an interesting design the wing anhedral won't be deterimental for stability, it will actually help at higher speeds. The biggest issue I see is that that wing and tail anhedrals will demand really long landing gears and definitely a tail dragger configuration.

Schimpfy

I like all of them, personally. Kind of like different versions from the same manufacturer. With this configuration it might look cool to have some unobtrusive pods on the wingtips just big enough for a wheel to drop down a foot or so. It works in my head anyway.

jrhottel

My opinion: Beautiful concept but very very unstable at slow speeds. Single engine operation looks impossible. It's not the way a light twins can be designed because of the workload placed on the pilot by asymmetric thrust during single engine operation. I know computers can do allot to tame unstable designs but that still seems a stretch. You'll need large effective control surfaces in any event. The layout looks more promising for the power to weight ratio and higher speeds of a jet. It would need long (heavy) landing gear unless maybe the wheel are in the wing tips. Still as a concept it's wonderful.

colbmista

landingear.jpg

heres a underbelly shot with the landing gear up and down

colbmista

and yes there is lots of clearance
clearnace.jpg

Knight26

Along the lines of JRHottel's comments, how about either angling the tail down more, or adding deployable vertical stab for low speed ops? Maybe even make the tail variable to hang down more in case of engine out operations, maybe another 25 degrees or so? The biggest issue there will be avoiding tail strikes on take off and landing, but a nose flat attitude on take off and landing would help avoid that.

Along those lines it looks like at your current configuration that you have 7 degrees of pitch angle before tail strike, assuming the "tail wheel" flexes. If the tail angle were levelled or reversed then it will be right around 10 degrees. Neither one is too bad, but if you angle the tail down more it will be an issue. Perhaps consider giving the tail the ability to angle up for take offs and landings, just in case.

colbmista

what would produce more thrust 2 prong or 4 prong propeller?

bosun

Knight26 is right, the tail needs to come down a lot more or this plane will need salt flats for runways; a flat take off or landing attitude means very high speed.

As for propellers, generally speaking you'll find 2 blades on planes designed for low speed flight like bush planes or aerobatic planes. More blades generally means the plane is designed for high speeds and high altitudes, and they usually don't have the acceleration or take off and landing performance of planes with fewer prop blades.

I doubt that a V tail could keep this design flying straight with one engine out. Most twins have relatively large vertical tails so that they can maintain full power on one engine with the other engine feathered. If you look at old multi-engine planes, many of them were designed with twin rudders so that the prop wash of the working engine would make the rudder work better; see the Beech 18, Lockheed 10/12/14, North American B-25, Consolidated B-24, and Lockheed Constellation for famous examples of multi-rudder multi-engine designs.

colbmista

i decided on positioning the tails upward now i mean i liked them facing down but to many problems lol i was also thinking of having the tail fins up and also adding some smaller ones in the down position as well not really sure on that one tho

jrhottel

Colbmista,

If you care about aerodynamics, I could give a very technical and grim assessment of the design. If you are interested consider this. Aerodynamics is a kind of scale. At one end you find gliders, airflow over the wings make lift, find an updraft or two and your in business. At the other end you find rockets. Higher speeds mean many times the control forces and you need only vestigial fins for controlled flight. Controlled flight aside, a large enough engine and you can make a freight car fly. Anhedral wings are less stable. At slower speeds and smaller control forces stability becomes paramount, particularly in single engine asymmetric thrust situations. Trust me, with one engine out, a pilot has to do everything right and work fairly hard with a inherently stable designs.

Ideas, your design has a predator drone like stance, look at how it handled similar design issues. With respect to high speed conventional twins, I'll give you a link. It was a race plane. Notice how the engines are close together to minimize asymmetric trust arm.

Unfortunately, design with an eye to the real world aerodynamic will most likely get you a fairly conventional looking light twin. Frankly, I suggest you throw the text book away and make something cool.


http://www.youtube.com/watch?v=66q4awWPArM

colbmista

new tail and some other minor detailnewtail.jpg