# Asymmetrical homebuilt aircraft concepts

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#### cluttonfred

##### Well-Known Member
HBA Supporter
Moderator note, posts taken into a new topic since it certainly deserves one:
https://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/14183-interesting-aircraft-4.html#post162056

I've alway wanted to try an asymmetrical single-engine homebuilt along the lines of the Blohm & Voss BV.141 and other unbuilt designs (see the Blohm & Voss section of Luft46.com). You could make an argument for crash safety with this layout (engine, fuel all separate from the pilot) but the real reason would be just for fun and to try something different. As this clip shows, it certainly doesn't make for an unmaneuverable aircraft.

Given the relative weights involved at the light aircraft scale, I'd go with a low-wing single-seater to start, with the pilot sitting over the wing at about 25% chord in a simple fuselage with glider-like visibility and the engine in a nacelle with a fuel tank between the two. Putting the rudder or an auxiliary vertical fin in the slipstream with either a definite airfoil contour or maybe adjustable incidence on the fin would counteract the yaw from the engine with power, much like a high-mounted horizontal stabilizer counteracting the pitch-down with power from pylon mounted engine. If you can mentally move the engine from the nose to the wing of this Moni motorglider than you have a pretty good idea of the concept.

For a two-seater, if you can imagine this Wing Derringer with just one engine and a small auxiliary find added to the stabilizer tip behind the remaining engine, then you have a pretty good idea of what I have in mind.

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#### skier

##### Well-Known Member
Re: Interesting Aircraft

I've alway wanted to try an asymmetrical single-engine homebuilt along the lines of the Blohm & Voss BV.141 and other unbuilt designs (see the Blohm & Voss section of Luft46.com). You could make an argument for crash safety with this layout (engine, fuel all separate from the pilot) but the real reason would be just for fun and to try something different. As this clip shows, it certainly doesn't make for an unmaneuverable aircraft.

Given the relative weights involved at the light aircraft scale, I'd go with a low-wing single-seater to start, with the pilot sitting over the wing at about 25% chord in a simple fuselage with glider-like visibility and the engine in a nacelle with a fuel tank between the two. Putting the rudder or an auxiliary vertical fin in the slipstream with either a definite airfoil contour or maybe adjustable incidence on the fin would counteract the yaw from the engine with power, much like a high-mounted horizontal stabilizer counteracting the pitch-down with power from pylon mounted engine.

Count me in for helping with this design, I've always wanted to do the same thing.

#### Lemans

##### Well-Known Member
Re: Interesting Aircraft

Hello Matthew,

Sounds interesting enough for a separated thread. My 2 cts, two small engines .. push/pull?

#### cluttonfred

##### Well-Known Member
HBA Supporter
Re: Interesting Aircraft

Sounds like a good idea -- attend MODS, could we split posts 124-126 into a new thread titled "Asymmetrical homebuilt aircraft concepts" please? Thanks!

##### Well-Known Member
Re: Interesting Aircraft

Sounds like a good idea -- attend MODS, could we split posts 124-126 into a new thread titled "Asymmetrical homebuilt aircraft concepts" please? Thanks!
Filing a report (small triangle) is usually quicker (not now). Excellent suggestion and I also think it's a good and viable idea if you can find appropriate engines. (Two Briggs and Stratton for a single, two VW's for a big twin/4-seater?)

#### skier

##### Well-Known Member
Given the relative weights involved at the light aircraft scale, I'd go with a low-wing single-seater to start, with the pilot sitting over the wing at about 25% chord in a simple fuselage with glider-like visibility and the engine in a nacelle with a fuel tank between the two. Putting the rudder or an auxiliary vertical fin in the slipstream with either a definite airfoil contour or maybe adjustable incidence on the fin would counteract the yaw from the engine with power, much like a high-mounted horizontal stabilizer counteracting the pitch-down with power from pylon mounted engine. If you can mentally move the engine from the nose to the wing of this Moni motorglider than you have a pretty good idea of the concept.

View attachment 22139
Based on some single seat aircraft comparisons that I've done in the past for a similar idea, I'd start with a 65 hp engine and shoot for a gross weight of 900ish lbs. Sheet metal construction.

#### Lemans

##### Well-Known Member
My current project is in building stage and will consume almost all my free time the next 6 months. However,if this idea leads some of us to something real... I will find some time to visualize your idea's on paper. I use Sketch-up, Auto-CAD , Inventor and possible Solid-works if my boss decides to go for the French Dassault group next month. The Dassault group offers 2 free viewers for 2D and 3D drawings witch we can use to view and modify drawings. Sketch-Up is free, Sketch-Up Pro is really cheap and is growing better every month. Sketch-Up Pro can read and export DWG-files witch can be used in more high-end CAD software.

A push/pull design always had a special attraction as I can't think of a safer way to propel an airplane. Apush/pull in an asymmetrical airplane will unite extraordinary characteristics.
If we need to vote on used building material, I vote for composites.

#### skier

##### Well-Known Member
I'd like to start by saying this is a project I've wanted to work on for no less than 7 years and it's a design I've started down the path towards multiple times.

Like most projects, everyone has their own thoughts. In order to start a successful design, we need to first come up with a list of requirements. I'll admit a bias for flying as cheaply as possible and that will definitely affect my suggestions. Along with Matthew's first suggestion, I would like to see this start as a small single seat prototype, with fixed gear, constant pitch prop, etc. The simpler the project, the more likely the project is to be finished and built. Twin engine, retracts, constant speed props are all good for efficiency/speed, but they result in a more expensive product and more time consuming build/design. Composites are exciting, as are the sexy curves they allow, however they require specialized design and analysis tools. Again, I'd like to see it stay as simple as possible; steel tube and fabric may be the easiest design (a truss is probably the easiest structure to analyze).

Since this is starting out on the forum, it will most likely be an open source project, but for it to go anywhere we will need find a design leader to make sure the project stays on track. Someone needs to have the final say in design requirements and can reject ideas if necessary. We also need to insure that people are willing to put in time to make it to the end.

Anyone else willing to put in the time/effort for a group project?

#### jhausch

##### Well-Known Member
My current project is in building stage and will consume almost all my free time the next 6 months. However,if this idea leads some of us to something real... I will find some time to visualize your idea's on paper. I use Sketch-up, Auto-CAD , Inventor and possible Solid-works if my boss decides to go for the French Dassault group next month. The Dassault group offers 2 free viewers for 2D and 3D drawings witch we can use to view and modify drawings. Sketch-Up is free, Sketch-Up Pro is really cheap and is growing better every month. Sketch-Up Pro can read and export DWG-files witch can be used in more high-end CAD software.

A push/pull design always had a special attraction as I can't think of a safer way to propel an airplane. Apush/pull in an asymmetrical airplane will unite extraordinary characteristics.
If we need to vote on used building material, I vote for composites.
Would openVSP be suitable for this?

OpenVSP

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#### Aircar

##### Banned
This topic has been posted much earlier , including CAD wireframes by Topaz of his asymmetric concept and links to the BV 141 and A Swedish asym design,the Rutan Boomerang et al --it brings up the data relocation problem with ever branching threads on the same subject and raises the question if some sort of consolidation procedure can be accomplished. (?)

Dan Raymer published his asymmetric single engine design in "simplified aircraft design for homebuilders" and in the mid seventies John H McMasters published drawings of two asymmetric self launching sailplane concepts --one titled "not reccomended" . (sailplanes tend to be manouvered near to stall and otherwise deviate from straight and level more than typical light aircraft --the spin behaviour (in either direction) of some of the asymmetric designs would be 'interesting' if not fatal. One self launching sailplane was built with asymmetric propeller location and written up in the homebuilt glider newsletter (the motor was on one wing driving a folding pusher prop aft of the trailing edge )

The rediscovery of technical enthusiasms 'just to be different' has been a feature of similar unconventional configurations and after the initial rush has subsided it often pays to study the history of those that were actually constructed --deeper design studies generally reveal reasons why they did not thrive.

#### rtfm

##### Well-Known Member
Hi,
I second Raymer's airplane which is painstakingly conceptualised in his paperback book. Wonderfully asymetrical. And all the hard bits are already done...

Duncan

#### Aircar

##### Banned
G'day Duncan - I hope you are still above water in your part of the world (the Eastern seaboard of Australia is being inundated with record setting rainfall and flooding) --also wondering if Alan (Head in the clouds) is still on dry ground ( I can't send emails thanks to my incompetent telco -Optus- and an ongoing dispute that the telecommunications ombudsman hasn't ruled on but they have jumped the gun (!) --I can still post on this forum so I hope Alan sees this and is OK with his workshop and house.

I guess a lot of you banana benders will be thinking of amphibians right now ...

##### Well-Known Member
G'day Duncan - I hope you are still above water in your part of the world (the Eastern seaboard of Australia is being inundated with record setting rainfall and flooding) --also wondering if Alan (Head in the clouds) is still on dry ground ( I can't send emails thanks to my incompetent telco -Optus- and an ongoing dispute that the telecommunications ombudsman hasn't ruled on but they have jumped the gun (!) --I can still post on this forum so I hope Alan sees this and is OK with his workshop and house.

I guess a lot of you banana benders will be thinking of amphibians right now ...
Hi Aircar - and apologies to others for the momentary thread drift. Yes, still above waterline though many poor sods aren't. Had an 'interesting' night which fell within the 24hrs/24 inches rainfall, pressure dropped to 994 which is within Cat 1 cyclone numbers, very unusual since we're nearly 10 degrees outside the tropics here. Would have been a normal summer night when I lived in the far north but of course houses aren't designed for those torrential and horizontal rain dumps in these latitudes. The screened verandah that serves as my workshop needed an awning at one end to keep the rain from going all over the electrics, project, benches, tools and machinery. So about 18mths ago I erected a small truck tarpaulin and it's been doing sterling duty as rain awning and sunshade.

In the middle of the night it decided to be cantankerous and break away from its moorings and head off toward the local international airport, which was pointless since that was closed due to the conditions. Once the awning was gone the sheetmetal decided it was time to fly around the verandah circuitously and see what mayhem it could cause. There wasn't much point in getting into waterproofs to deal with it since nothing would keep you dry in those conditions and it wasn't cold so for a few minutes the neighbours would have been amused at the antics of a pyjama clad nutcase running around trying to catch pieces of lethal airborne sheetmetal before they sliced the AussieMozzie to bits. Gladly I was able to duck the potential decapitators at first but it got more tricky once the power failed and one had to gauge the trajectories from the stroboscopic effect of the lightning flashes, probably more amusement for the neighbours having the benefit of freeze-frame imagery.

In the morning my lovely wife was furious with me and the hundreds of parrots that she feeds in the garden were furious with her. It seems that weather events are the fault of the one you most love.

Re-rigging the tarpaulin in the morning was a delight of course, on top of a ladder in blinding rain and 60kt winds holding onto the corners of a flailing sail just wasn't going to cut it so I had to recall the days of sail-racing and diaper the bastard, re-secure the corners and two edges that attach to the building, but all with long lanyards to allow for the diaper, then cut the bonds. The opening shock was reminiscent of a canopy after free-fall then haul like hell on the warps. Gladly the only thing that was twisted was me and we're now back to the status quo, my wife even likes me again because I also re-secured her climbing cucumber plants which had adopted a hanging garden attitude.

Thanks for your concern, just another day on the wonderful Gold Coast - Beautiful one day, Perfect the next...

#### rtfm

##### Well-Known Member
G'day mate. All high and dry here. Trees down all over the place, debris in the streets, power off etc. But this time round, we're OK. Alan - you OK?

Duncan

#### cluttonfred

##### Well-Known Member
HBA Supporter
My vote for a low-cost proof-of-concept demonstrator is a very small single-seater powered by a cheap 1835cc VW. My preference is for wood and/or bolted and riveted square aluminum tube construction to keep the required skill level and materials cost down, though I am happy to incorporate composites if of the relatively low-labor variety, such as pre-cured skins that would be bonded to a wood and foam basic structure. A tractor-mounted engine would keep installation and cooling more conventional. One alternative we haven't mentioned but which I would certainly consider is a twin-boom, twin rudder design with with the horizontal stabilizer joining the fuselage containing the pilot with the boom coming back off the engine pod. Think Scaled Composites Pond Racer minus one engine, boom and rudder but of course adapted for much simpler design and much less power.

#### Lemans

##### Well-Known Member
Hi Skier,

As I'm willing to throwinn free drawing power, I vote for an open project. The most simpleand most complex machines starts their life as an idea. The way anidea takes form is often a surprising journey, short turns, dead endsand so on. As long as the traveler likes the route, it's notimportant how far he needs to travel before reaching his destiny.
However, 95% will quitlong before and I must say that I have more respect for the loserswho tried anyway than for all those who never tried at all.
So, count me inn if youneed a high tech pencil. If needed, I will look into free programs tosee if they could be use-full for our needs.
First big task is findingenthusiasts located close enough to each other to form a buildersgroup.
Drawings and small partscan be made around the globe and send over but that's it.
The rest needs to boughtand assembled near the design leader workshop.

Hi jhausch,

It should be use-full ifwe are willing to learn what this software offers.
Recently I have lookedinto Sketch-Up as designing tool for a sport-prototype race-car.
As 18 year old's have nomoney for commercial programs they have to work with what'savailable.
It's surprisinglypower-full and will help these young mechanics to build their dream.

#### jhausch

##### Well-Known Member
There are some great videos on that site that shows what the SW can do. I only mention it because it seems to output data useful to other programs and be tailored to aero design....

#### Rick McWilliams

Solidworks is suitable for a simple airplane design. The student version of solidworks has full functions. It costs about $100. The student version can be used for 18 months. It is relational so you can make big changes and all of the parts will adjust to fit. #### Jay Kempf ##### Curmudgeon in Training (CIT) Lifetime Supporter Solidworks is suitable for a simple airplane design. The student version of solidworks has full functions. It costs about$100. The student version can be used for 18 months. It is relational so you can make big changes and all of the parts will adjust to fit.
Or blow up because the relations weren't thought out well...

#### Rick McWilliams

##### Well-Known Member
Solidworks requires some skill. Complex organic shapes can get tricky with global shape changes. It can be very frustrating to break a model with that last tweek. There is usually a work around to any Solidworks bug. As the design proceeds more and more of the geometry will be frozen.

I have a hot button for Solidworks bugs that have been around for a long time. The other CAD alternatives are not any better. I love conic surfaces. These are not a part of Solidworks, I use an add in GW3D.