Another day, another new idea

The one on the right is the two place - if you look close you can see the two heads. The larger fuselage is a stretch of the single place, which gives it that longer, sleeker look. I gotta admit, I also like the longer look better, but I'm not sure whether I want to go with a two place before the smaller one. But from the development standpoint, the slightly larger surface area wont cost all that much more to develop than that of the single place so maybe, if I consider this as a potential business issue, maybe the larger airframe makes more sense.

Well, there's much more to do and analyze so the decision doesn't need to be made now.

From a purely aesthetic point of view, disregarding all practical and logical considerations; a design that looks almost supersonic standing still really needs to have its wheels tucked away. I always thought the look of aircraft like the Variezes etc and other fast looking machines is completely spoiled by the clutter of landing gear hanging beneath it, no matter how well faired. Take a look at how much better a Velocity looks, for example, with the retractable gear.

Like I said - no logical reason to do this on a relatively slow and light airplane. but from a marketing point of view, I think looks sell.

I agree completely - back when I was into RC stuff I really disliked building my airplanes with the fixed gear but unfortunately at that point in time there weren't too many options for retracts, unless of course you built them yourself.

And as you say, the same applies here. But developing retracts is not a cheap proposition (I'm doing it now on two of my current contracts), both from the design standpoint nor from the fabrication one, so my current thought is to come up with a somewhat "attractive" fixed gear, to be followed up later with retracts.

Of course I don't know whether this'll be a real product yet, but I am trying to think ahead a bit in order to see what part of this is feasible near term, and what might be done later. Given current costs of low volume fabrication, the gear might introduce about a $10k to $15k (or more) hit onto the kit price. Picking preliminary numbers out of thin air, if I shoot for a basic composite parts kit price to be let's say around $35k (assuming prepreg graphite construction), a 25% or more increase in price just to get the sleeker look and maybe five to ten knots of additional speed is a serious consideration.

But in general, yea, it does look much better without the gear hanging down. And I think that would definitely be a must if I were to ever consider a jet version.

Originally Posted by orion

But in general, yea, it does look much better without the gear hanging down. And I think that would definitely be a must if I were to ever consider a jet version.

Did someone say jet?

http://www.homebuiltairplanes.com/fo...5&d=1214401772

One idea from the above pic is a streamlined fixed main gear with a opening/closing wheel fairing. Apparently the struts also acts as vertical stabilizers. Although not as pretty as a full retract it is "smoother" looking than most fixed main gears and might even eliminate the need for vertical stabs on the wing tips. Just a thought.

Originally Posted by Lucrum

http://www.homebuiltairplanes.com/fo...5&d=1214401772

One idea from the above pic is a streamlined fixed main gear with a opening/closing wheel fairing. Apparently the struts also acts as vertical stabilizers. Although not as pretty as a full retract it is "smoother" looking than most fixed main gears and might even eliminate the need for vertical stabs on the wing tips. Just a thought.

WTF is that thing? looks like some strange metallic goose. Russian?

It's an unrealistic concept built by a relatively well known industrial artist - it's not feasible due to several features of the layout but it is interesting to look at and yes, even imaginative.

Rudders:

How about a rudder on each side, and part of, the shroud? One would always be in free air, and the other in the prop wash.

or

lose the shroud and go with a V tail...or Y, which I like better, especially on the 2 man.

The only thing is about the "V" or "Y" tails is that ideally, you do not want any structure, especially movable structure, within about half the diameter of the prop. So, if you move the surfaces forward they'll end up too close to the CG and thus become much less useful. Besides, I like the low and sleek look - adding the tail on top of the fuselage would make it somewhat ungainly. I like the tip verticals - they'll do the job and should be relatively easy to rig up as rudders with two simple electromechanical actuators.

One quick update: I've done a bit of rethinking of the approach and although I'm not wholly convinced yet, from a marketing and use standpoint, it does seem to make more sense to develop the two place rather than the single. Given the amount of work and tooling that'll be needed, developing two separate airframes, especially considering the limited utility of the single place, just does not seem to make a lot of economic sense. Like I said, I'm not fully convinced yet because I really did want a small one, but effort is effort and doing it twice is something I might not have time for.

hmm.. somewhere I've seen a plane with a Y tail just before a pusher prop on the end of a long boom... will look.

But, I have to agree, the tail-less look is really cool

Yea, the Mini-Imp. But the surfaces were just a hair forward, although not as far forward as would be ideal. But he did have prop harmonic problems and so ended up having to fly only with wood props. But for the Mini-Imp that was OK since the lighter weight wood was in its favor.

Another configuration of that type was the Learfan. But there the surfaces were positioned relatively well. The prop was positioned further aft on the tail-cone extension.

the Learfan was it.. but the prop is smaller than I remembered, so the position of the surfaces are actually forward, as you say.

The mini-imp is cool, however

How about something like the Tomcat? With two widely separated rudders. Perhaps the rudders could also be "pseudo-shrouds" for the propeller?

In order for a shroud to be effective the tip clearances have to be only on the order of a few thousandths. Actually, most optimal applications incorporate a small thin wear strip of foam at the prop's location so the prop can make its own groove and thus achieve a near perfect tip seal. Obviously the verts like that would have no effect.

But the main problem with this is that if you put the verts near the fuselage they will provide little to no benefit since the majority of the flow they'll see is that which is controlled by the fuselage. As such, if the airplane should yaw, the fuselage will turn the flow parallel to it upstream of the verts, so by the time the flow reaches them(assuming they're within about 1.5 span length of the body), they'll only see the parallel flow and thus provide virtually no yaw stability.

Originally Posted by orion

In order for a shroud to be effective the tip clearances have to be only on the order of a few thousandths. Actually, most optimal applications incorporate a small thin wear strip of foam at the prop's location so the prop can make its own groove and thus achieve a near perfect tip seal.

Intriguing! I would assume that when you talk about a shroud being effective, you mean that it actually increases propellor efficiency, right? I would also further guess that the main benefit is due to "containing" the tip losses.

Dumb idea time: Would it make any sense at all to design, build, and test fly a pusher without a shroud (but making allowances in the design for the extra weight/wetted area of a shroud)... and then later add the shroud? You're previous posts (and general history of planes with shrouds/ducted fans) has me pretty well convinced that I don't really want one from an efficiency point of view... but I'm intrigued by the possible noise-lowering benefits for the nimbys on the ground.