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Modern day "motorcycle of the air" aircraft class?

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erkki67

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The little grey bird, seams to me a bit small to lift a hefty pilot, it's precursor the bigger grey looks by far more reasonable!
It's getting very close to my own ideal, except mine should be a wooden/fabric construction with a classic LDG.
The tail volume I imagine as all flying surfaces.
Such a wooden bird with a B/S, Kohler or Harbour Freight V-Twinbin the nose would fit quiet well within any FAR103 or any other microlight class WW.

rki
 

TahoeTim

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The plank is awesome. Would it work with Ercoupe style landing gear under each boom? The motorcycle swing arm/shock look on landing gear would be the ticket. I need to pay someone to create a set of plans so I can build a plank!

E5_moo-sb_E222_54_moo1-1p3_.jpg


My plank would have booms less than 8ft wide for trailering. The fuel tanks would be in the center section. Pop on the wings outboard of the booms and go flying. It would be a modern pusher Ercoupe style of plane with coupled rudders too. Who wants to design it for me?
 

FritzW

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The plank is awesome. Would it work with Ercoupe style landing gear under each boom?
I think the wing would have to be lowered a bunch, or the gear legs would have to be really long.


My plank would have booms less than 8ft wide for trailering. The fuel tanks would be in the center section. Pop on the wings outboard of the booms and go flying.
The booms are 84" apart.

It would be a modern pusher Ercoupe style of plane with coupled rudders too.
Maybe the 'B' Model could have "coupled rudders" ;)
 

Victor Bravo

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Like!
Like!
Like!

"Forrrr he's a jolly good fellow..." !

What do I need to provide for you to refine this towards the next step? What dimensions, or sketches, or answers do you need?

I believe I posted the (rough) cross section of the "typical" wing station. We'll start with the same flat-bottom VP-1 airfoil for now, let's just leave room for another (similar flat bottom) section to be selected if it is later shown to be appropriate.

The angle on the rear of the main spar caps was envisioned to be 1/8 x 3/4 or 1/8 x 7/8 standard extrusion, to be determined. For this initial model, assume that the laminations on the front of the spar cap are 1/8 x 3/4 strips, with three of the strips at the root third of the wing, reduced to two strips at mid-span, reduced to one strip at the outer third of the span. Solid AN 470-4 size rivets go through all of these laminations, and through the chear web, and through the angle. For now, use .032 sheet metal for the shear web, which can perhaps be reduced later after the "real" calculations.

After much agonizing internal debate, for simplicity and reliability the fuel tank will have to go behind the engine and forward of the pilot, essentially in the same position as a motorcycle. The instruments (very minimal) will be at the rear of the fuel tank. For now, use a shape like this:
https://upload.wikimedia.org/wikipedia/commons/8/85/Triumph_T_110_650_cc_1954.jpg

FOR NOW, just butt the two wings against the side of the fuselage with no fittings. I'm sketching out how I want to join the wing halves and the fuselage for trailer/disassembly. Don't spend any time rendering that joint yet because I haven't decided the best way to do it.

Again, THANK YOU andlet me know what other parts to the puzzle I can provide to move this rendering forward.
 

FritzW

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Here's a good analogy:

In order to draw the airplane you need just as much information as you'd need to build the airplane. Anything less than that and your asking me to design the airplane, ...then draw it.

I'm more than happy to convert "bar napkin" sketches into working drawings and CAD models (real drawings, not just the eye candy we've been playing with) but you gotta give me something to work with.

ie. It's completely impossible to make any sort of drawing based on this information.

"The angle on the rear of the main spar caps was envisioned to be 1/8 x 3/4 or 1/8 x 7/8 standard extrusion, to be determined. For this initial model, assume that the laminations on the front of the spar cap are 1/8 x 3/4 strips, with three of the strips at the root third of the wing, reduced to two strips at mid-span, reduced to one strip at the outer third of the span. Solid AN 470-4 size rivets go through all of these laminations, and through the chear web, and through the angle. For now, use .032 sheet metal for the shear web, which can perhaps be reduced later after the "real" calculations."

Like I said at the bottom of page 53 "Post your pencil sketches, if there's enough detail to work with we can whip up a solid model of it pretty quick."
 

Victor Bravo

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Not asking you to design it, I'm designing it, with help from a friend who has volunteered to do the stress calculations that I cannot.

My understanding is that once you have a rendering of it in SolidWorks, that program allows you to easly find or derive many dimensions, shapes, etc. that would have been painstaking and less accurate doing it by pencil drafting.

So if I said that there are bulkheads every 18 inches, SolidWorks can make a "cut" every 18 inches along the fuselage and arrive at the outer dimension, after whigh the bent flange thicknesses and skin thicknesses can be subtracted, leaving you with an accurate size and dimensions for each of those bulkheads.

Is this not the case?

Have I assumed that something is a couple of clicks away in SolidWorks that in reality represents a lot more effort than that?
 

FritzW

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Have I assumed that something is a couple of clicks away in SolidWorks that in reality represents a lot more effort than that?
No, if you sketch it out it's only "couple of clicks away".

Again, like I said on page 53 "Post your pencil sketches, if there's enough detail to work with we can whip up a solid model of it pretty quick."

And on page 55 "...Sketches Man! ...I need sketches!"

As promised, I "whipped up your solid model pretty quick" based on the sketches you posted. And I'll be happy to help you with the real CAD model (where the real drawings will come from) if you give me sketches with enough detail.

And yes, things like pulling out bulkhead profiles and goofy wing tip rib profiles are simple. But if you haven't done any stress or aerodynamic work yet, what would be the point?
 

erkki67

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For sure I like the layout of the grey bird, but for me it still have some drawbacks, as I've already communicated with Fritz.

sheetmetal is fine as long as you live in the U.S. , wood would be better if you are living ww.

To become popular at least a two wheel main gear would be required if not even a tricycle nose gear!

the smaller the bird is, the higher are the speeds required to keep it aloft, so for my size the original size of the gray bird was more of interest.

The rudder I would like to have would be an all flying one, and more of a Zenair or Jodel style, straight lines.

rki
 

nestofdragons

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Innovation is a nice thing. But innovation also knows less customers. Last year i walked between the lines of the airplanes and i only saw ONE airplane with a single central wheel. I think it was a Europe (name of model). Even if they are maybe better in performance (due to less weight and less drag), people will try to avoid them because they are not what they expected. Especially not in a classic looking airplane. If you go toooootally non-conventional then it might be that the special landing gear is not something people will as being the point why not to buy it. But ...the rest of the design might be. Beware! Innovation is not always good for your own wallet.
 

BJC

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Innovation is a nice thing. But innovation also knows less customers. Last year i walked between the lines of the airplanes and i only saw ONE airplane with a single central wheel. I think it was a Europe (name of model). Even if they are maybe better in performance (due to less weight and less drag), people will try to avoid them because they are not what they expected. Especially not in a classic looking airplane. If you go toooootally non-conventional then it might be that the special landing gear is not something people will as being the point why not to buy it. But ...the rest of the design might be. Beware! Innovation is not always good for your own wallet.
Some discussion about mono vs bi gears here Europa Aircraft | Europa XS Monowheel Overview


BJC
 

nestofdragons

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Recently i found out that a very very basic airplane (also having a central wheel) stopped its activity due to low sales. The airplane was a treasure in simplicity and ...had good looks. But ...it was too weird to be a good selling product. It is sad to see it disappear. It was from i guess a ex-Soviet country. Sometimes you find very very good designs from those countries.
 

Victor Bravo

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OK... you guys busted me... You caught me being a good salesman. But being a good salesman has an advantage once in a while :)

I wanted to wait before I discussed this too much, but some people might remember that I did discuss some of this on the VP-21 thread a while back.

The prototype AeroCycle will have a mono-wheel. It is more attractive, and it fits best with the "motorcycle" aspect that started this entire thread. It is lighter, faster, climbs better, cheaper, easier to build, lowest parts count, and it cures the common cold.

It also looks the best in the advertising materials, and it looks best in this online discussion thread that has delightfully captured all of our interest (including myself). "AeroCycle", and the entire mystique/lifestyle/visual dream that it invokes, does not conjure the image of a tricycle landing gear, my dear friends :)

But there will be 2 and 3 wheel landing gear options developed if it becomes appropriate for any future commercial product.
 

bmcj

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Here's a good analogy:

In order to draw the airplane you need just as much information as you'd need to build the airplane. Anything less than that and your asking me to design the airplane, ...then draw it.

I'm more than happy to convert "bar napkin" sketches into working drawings and CAD models (real drawings, not just the eye candy we've been playing with) but you gotta give me something to work with.

ie. It's completely impossible to make any sort of drawing based on this information.

"The angle on the rear of the main spar caps was envisioned to be 1/8 x 3/4 or 1/8 x 7/8 standard extrusion, to be determined. For this initial model, assume that the laminations on the front of the spar cap are 1/8 x 3/4 strips, with three of the strips at the root third of the wing, reduced to two strips at mid-span, reduced to one strip at the outer third of the span. Solid AN 470-4 size rivets go through all of these laminations, and through the chear web, and through the angle. For now, use .032 sheet metal for the shear web, which can perhaps be reduced later after the "real" calculations."

Like I said at the bottom of page 53 "Post your pencil sketches, if there's enough detail to work with we can whip up a solid model of it pretty quick."
OK, point taken. Maybe this will clarify it...

It's not quite a high wing and not quite a low wing, it's not huge nor is it big or medium, the nosewheel is on the tail and the whirlything goes on the front. Oh yeah.... it's fast.

Oh, wait... Nevermind, I found it:

image.jpeg

Guess I should have mentioned the green too. :gig:
 

Victor Bravo

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And I'll be happy to help you with the real CAD model (where the real drawings will come from) if you give me sketches with enough detail.

But if you haven't done any stress or aerodynamic work yet, what would be the point?
The point is to get a reasonable start, and then adjust the aerodynamics. This is the method that worked for Rutan on dozens and dozens of his successful designs. And I'm starting with much less innovative or weird basic configuration layouts than he did. I'm a simple old model builder, and all of that prized knowledge is not necessarily "gold" on all full-size airplanes, but it is a good starting point on a low and slow airplane like this. Fritz, I'll bet you a bottle of Macallan that the final 'engineer-approved' version is less than 5-6% different (flying surface areas, tail moments, outlines, thicknesses) than my sketches :)

It is fully and completely understood that having a simple analysis done on the aerodynamics is beneficial. No way no how no chance that I'm not going to have someone take a look at this before it is "finalized". There are plenty of folks on this forum alone who can do that if they become interested enough.

But not all of aerodynamics is counter-intuitive on a simple "normal" airplane like this. Common sense (and 80 years of history) tells us that we pretty much know the 4412 or Clark Y (and several other similar flat-bottom sections) works safely and well on a low speed airplane. We know that there needs to be a fair chunk of side-view profile behind the wing and under the stabilizer for spin resistance/recovery. We know that the axle (taildragger version) needs to be slightly, but not a lot, in front of the leading edge. We know that the H-stab and V-stab should have moderate to thick symmetrical sections (NACA 0009 being the most obvious and well-proven). We know that half span ailerons, with 20-25% chord length, will provide solid, safe roll control at low speeds and high AoA. We know that having 1/3 more upward travel on the aileron than downward travel will be a safe (if not overly conservative) insurance policy against a serious adverse yaw problem. We know that moving the ailerons inboard by 5% and tapering the wingtip, especially sweeping the leading edge only, provides a bit extrasafety and an improvement in low speed handling. We know that a rounded wing tip with the bottom tapering upwards (Ercoupe, as drawn in Fritz' rendering) although not as efficient, is visually pleasing and has reasonably good manners.

We also know that sharply tapered trailing edges and pointy little wingtips (numerous old Russian designs) is not good for low speed handling and causes some very nasty stall behavior that would be inappropriate for this class of aircraft. We know that putting the H-stab on the very bottom of the fuselage under the V-stab has a good chance of "blanking out" the V-stab at and below stall AoA, when you need the V-stab the most.

So using this history based common knowledge to get reasonably close, before the full CFD analysis, is probably acceptable... on a small, simple, "giant model airplane" type of project like this.

As for structure, the entire concept was envisioned and laid out (thus far) with room built in for structural details and adjustments to be made without wrecking the original layout. Meaning that the notches in the ribs and bulkhead corners will allow for additional spar cap or longeron material to be added with only minor changes. For example, my initial guess was a piece of 3/4 x 1/8 angle plus three laminations of 1/8 x 7/8 for the spar caps at the root, and "stepping" these laminations down to one at the tip. You can bet your backside that I'm not going to trust that first guess all the way to the test flight (not even to the sandbags!).

But if engineering calculations reveal that I actually need four laminations at the root instead of three, it does not change the rib much. Won't change it at all if I leave room for those additional laminations in the rib from the start. Likewise, the notches or corner reliefs in the bulkheads will be sized to allow for an additional lamination of a doubler strip on the longeron angle.

Did I mention that in general 2024-T3 is about 1/3 "stronger" than 6061-T6 but only costs 5-10% more? I left that in there as an option for spar caps and longerons too... yooo-betcha-life :)
 
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