Concepts only: Doodles without numbers

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DaveK

Well-Known Member
Joined
Apr 21, 2007
Messages
377
Location
Northern California
Looks a bit like a Vega Gull.
The time finally came to temporarily get away from all the aircraft design and performance code writing, put some put pencil to paper, and begin to figure out what my design should look like (based on the preliminary output data from my code). Below is where things stand today. With this basic layout accomplished, I can now go back to the code side of things to continue developing the design. The lines are not perfect in what's shown, but again, the main purpose of this particular CAD work was to allow me to start refining the layout so I could plug some necessary data back into my code.

The airplane is being designed to be:
- 2-place
- LSA-compliant
- Continental O-200-powered

I consider the Globe Swift to be one of the prettiest airplanes ever built. You may notice a resemblance to that as well as the Morrow Victory Trainer.
View attachment 117258View attachment 117256View attachment 117255View attachment 117257
 

jedi

Well-Known Member
Joined
Aug 8, 2009
Messages
2,792
Location
Sahuarita Arizona, Renton Washington, USA
Just artwork without the pressure of technical claims, details, etc.

I'll start

Something fast
View attachment 116789
Isn’t redesigning those old airplanes a bit like reinventing the wheel?

It’s not that I am against redesigning the wheel. I think it is about time the wheel had a major redesign.

It is about defining the problem. Tell me again. What is the goal here?

Something fast doesn’t really define a mission. Without a defined mission you are not designing, you are.daydreaming.

That’s ok. Have fun. Just realize what you are doing. I think I may be getting a wake up call here also.
 

cluttonfred

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HBA Supporter
Joined
Feb 13, 2010
Messages
8,674
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World traveler
Very pretty, Joe, though I would take a careful look at that tail as it does look very classic. In this case that's not necessarily a good thing when it comes to spin recovery. It looks to me like the horizontal stab and elevator risk blanking almost all of your fin and rudder in a spin, at least per the old 60°/30° wake rule of thumb. There are plenty of ways to fix that but the spin behavior is definitely something to consider.

rudder blanking.jpg

The time finally came to temporarily get away from all the aircraft design and performance code writing, put some put pencil to paper, and begin to figure out what my design should look like (based on the preliminary output data from my code). Below is where things stand today. With this basic layout accomplished, I can now go back to the code side of things to continue developing the design. The lines are not perfect in what's shown, but again, the main purpose of this particular CAD work was to allow me to start refining the layout so I could plug some necessary data back into my code.

The airplane is being designed to be:
- 2-place
- LSA-compliant
- Continental O-200-powered

I consider the Globe Swift to be one of the prettiest airplanes ever built. You may notice a resemblance to that as well as the Morrow Victory Trainer.
View attachment 117256
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
2,223
Location
Canada
Very pretty, Joe, though I would take a careful look at that tail as it does look very classic. In this case that's not necessarily a good thing when it comes to spin recovery. It looks to me like the horizontal stab and elevator risk blanking almost all of your fin and rudder in a spin, at least per the old 60°/30° wake rule of thumb. There are plenty of ways to fix that but the spin behavior is definitely something to consider.

View attachment 117274
Military trainers have been forced to develop at least 5 distinct fixes for this spinning problem.
The first fix locates the horizontal tail farther aft (ala. F4U Corsair) to expose the vertical fin to more wind blast.
The second fix installs the horizontal tail farther forward to improve airflow over the rudder.
The third fix installs the horizontal tail farther up the fin to expose more of the rudder to clear airflow.
The fourth - and ugliest fix - is to bolt on a wide variety of dorsal fins, ventral fins, under-fuselage strakes and leading edge extensions ahead of the horizontal stabilizer (ala. Pilatus and Tucano trainers).
The fifth fix is a longer aft fuselage. The longer tail moment arm will improve stability, but not airflow over the rudder.
If that were my pet project, I would mount the horizontal tail on top of the upper longerons and maybe a bit farther forward. I would also bulge the lower part of the rudder (ala. Ghiles) to increase chord and increase the amount of rudder area exposed to clear airflow.
 

Joseph Doherty

New Member
Joined
Jul 6, 2019
Messages
2
Location
Rhode Island
cluttonfred, I absolutely hear ya. All extremely valid points. Achieving that classic tail design while also maintaining good spin behavior will take some decent thought.

What's shown in those images represents something still pretty early in the development stage. The main reason I got away from the math/coding side for a second was so I could get the basic airplane "shell" together, determine what would be most appealing to me aesthetically, and get some kind of starting points for empennage sizing (and then more refined CG analysis and then subsequently static stability analyses). Other than that, doing this basic shell model allowed me to appropriately size the fuselage for the chosen powerplant and cockpit layout (ergonomics, sizing to a pilot of my size, etc.).

I own a 1946 Aeronca Champ, so it has helped tremendously having some sort of baseline for laying out the cockpit. In fact, using available Aeronca engineering drawings from the 1940s, one of the earliest steps I did in all this (other than a TON of software coding) was to model up a portion of the Champ's cockpit so I could get a clear picture how exactly I fit into that. The design in the previous images is a bit more spacious for the front-seat pilot.

IMG_5570.PNG

By the way, several years ago I worked as an aircraft designer/engineer in my day job. Images below show a concept I was working on back then.

LSA Concept Image - 1.PNGLSA Concept Image - 2.PNG
 

EzyBuildWing

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Joined
Sep 23, 2009
Messages
370
Location
Sydney NSW Australia
Looks a bit like the all-wood aerobatic Corby Starlet ........ maybe a 914-powered Starlet would be awesome?
Or maybe an all-metal "Parker Teenie Two" with a 914 up front would turn heads!
 

John.Roo

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Joined
Oct 8, 2013
Messages
1,070
Location
Letohrad / Czech Republic
Looks a bit like the all-wood aerobatic Corby Starlet ........ maybe a 914-powered Starlet would be awesome?
Or maybe an all-metal "Parker Teenie Two" with a 914 up front would turn heads!
... or like Spacek SD-1 with "classic" elevator position ;)
Also all wod construction.
1635167382902.png
 

REVAN

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Joined
Dec 6, 2016
Messages
345
Location
Tucson, Arizona USA
@REVAN - have you considered building one as a RC Glider? (3d printed in LW-PLA), looks like a great bird.
The story behind the Owlet:
@jedi posted an article on "Would planes be better if they were more like birds?", or something like that. The article linked to other resources, where I found a 3D scan of Lily, the owl, gliding through a flow-vis plane. They had this weird and lumpy stl file of the 3D scan. I downloaded the file and then reverse-engineered it, cleaned up all the weird lumpiness and put a nice looking glider-like body on it.

If anyone wants to try to create a physical model, or do some CFD analysis of this, I posted my work on GrabCAD, where you can view Owlet in a 3D viewer and download the STL to print or work with on your own. If you do anything cool with this, please let me know of your progress.

You can find Owlet on my GrabCAD page at: Ron Evan Smith | GrabCAD
 

EzyBuildWing

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Joined
Sep 23, 2009
Messages
370
Location
Sydney NSW Australia
I can't get Opal Facet outa' my head...!!!.. Nest of Dragons website has detailed info on ICE version.... my doodling produces jet version, enlarged slightly and with single fin and rudder. Simple conventional wing construction. Would be an absolute dog to fly/land etc....but hey, standing on the ramp it'd certainly pull crowds!
Gotta' build a quarter-scale jet-model first, but can't figure where to put the intake(s) without destroying sleekness!
Any ideas, anyone?

Facet Opal modified for Jet engine.png
 

REVAN

Well-Known Member
Joined
Dec 6, 2016
Messages
345
Location
Tucson, Arizona USA
I can't get Opal Facet outa' my head...!!!.. Nest of Dragons website has detailed info on ICE version.... my doodling produces jet version, enlarged slightly and with single fin and rudder. Simple conventional wing construction. Would be an absolute dog to fly/land etc....but hey, standing on the ramp it'd certainly pull crowds!
Gotta' build a quarter-scale jet-model first, but can't figure where to put the intake(s) without destroying sleekness!
Any ideas, anyone?

View attachment 117306
I assume simplicity of construction is the main attraction for a plane with this configuration. How much more effort would be involved to sweep the wing? If relatively easy to do, it could make for a significantly better flying-wing aircraft, even while restricting the wing to a constant chord design. With sweep, any washout added to the wing will be pitch stabilizing, especially when added to the tip. I would add a nice raked wingtip to the ends of the wing with twist in the raked tip. Make the wing simple to construct, but then add a 20% tip extension that provides +90% the benefits of a fully tapered and twisted wing.

Even adding this kind of wingtip to a non-swept flying wing would have big advantages. Your drawing already has the beginnings of this. Reverse the direction of the trailing edge outboard of the aileron/elevator control, blend that with the leading edge and put reflex at the back end to raise the trailing edge as it reaches the tip. Then scale that tip to as large as is convenient for your tools and processes to work with. If you are going to make a nice blended wingtip anyway, why not make one that works good as well as looks good?
 

Riggerrob

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Joined
Sep 9, 2014
Messages
2,223
Location
Canada
New Russian pusher can drive along the road with wings folded.....reminds me of the Breezy Bubble Plane which had a Bell 47 bubble on the front, and the Edgeley Optica...... vid is in Russian....

Those silly Russians managed to build an survellance airplane - with a view similar to Edgely Optica - for about 1/3 the price. Next thing you know those silly Russians will build airplanes that can be repaired by tractor drivers from collective farms.
Hah!
Hah!

For those who missed my sarcasm, I was referring to crudely finished Soviet World War 2 airplanes and tanks that killed thousands of fascists.
 

Hot Wings

Grumpy Cynic
HBA Supporter
Log Member
Joined
Nov 14, 2009
Messages
8,023
Location
Rocky Mountains
I doodle in Solidworks. Much less mess than a stack of graphite smudged graph paper.
doodle.JPG
This is what is on my screen at the moment.
Reason for this doodle is I don't have room to build an AV-36 and the fuselage for the AV takes as much time to build as the wing - and needs considerable modification to make it suitable for ground operation with power.
The above doodle is based on the Debreyer Pelican, which was based on the AV-36. It has a root wing chord identical to the AV-36 and part 103 wing area. They all use the same Fauvel 17% airfoil. I figure the fuselage for the Pelican clone can be directly transplanted to an AV-36 wing as long as the hard points on the spar are compatible.

I'll be buying the spar material* in a couple of hours when I go pick up some lumber needed to finish up my work area(s). I'm getting close enough to having work area finished I've allowed myself a little time to doodle.

* not wood.........will need testing. For $30 per plane the cost of failure, during testing, is acceptable.
 

Hephaestus

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Joined
Jun 25, 2014
Messages
2,336
Location
YMM
Untitled-Snark-ish.png
That J2 derived design got some snarky lines in recent times.

But like the snark, it appears it'll need a solution to being a tail-sitter.
 

EzyBuildWing

Well-Known Member
Joined
Sep 23, 2009
Messages
370
Location
Sydney NSW Australia
Facet Opal from Scott Winton.....retain original proportions but just make everything 25 % larger, and have twin fins and rudders with more streamlined rake, and a jet engine......et voila!
Easy to build Hershey-bar wing,..... Carbon-fibre tubes for spars, and routed plywood ribs..

Opal Facet Twin Fins 30th October 2021.png
 

Lendo

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Joined
Feb 6, 2013
Messages
866
Location
Brisbane
Riggerob, Interesting Russian Design, I like it!
Its similar to a previous German mid fuselage prop pusher design, but can't remember the name. it does look odd but everything does something. The only thing I can't work out is those rods coming out of the landing gear legs, perhaps their something to do with the suspension dampening?
George
 

Lendo

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Joined
Feb 6, 2013
Messages
866
Location
Brisbane
Riggerrob. here's the Photo of the German Aircraft similar to that Russian Design, still can't remember the name, but always like that design approach.
George
 

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