Aluminum Tube & Gusset Airbike / Legal Eagle / Parasol Thread

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ScaleBirdsScott

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Feb 10, 2015
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I've used the spike method and it works well especially if you're using a V brake. I've also used it with regular bending brakes but you have to allow for some offset.

A belt sander and/or file, even a 3M grinding wheel, whatever you're already using to deburr the parts, makes them dissapear in no time.
 

addicted2climbing

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Jan 27, 2012
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Glendale, CA
Onshape estimates around 24.4#
Hello Ollie,

wow 24lbs thats good. For your reference the skylite as seen here in 4130 (not including welds) is 31lbs. There are a few sacrificial tubes in there that will be removed, but the welds may take that back up. So if you don't mind my asking what tubing size is your fuselage made with and will you do an FEA to verify its strong enough?

1588723173568.png
 

Ollie Krause

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Feb 26, 2020
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103
Ollie...I think what he means is you would use the spikes to align the gusset in the "bend jig" so you get the bend axis perfect (each spike 180 degrees out from each other along the bend axis) Then once bent you would not need the spikes anymore and simply nip them off so to speak.
Oh that make sense. I totally didn't even think about how I would do the actual bending so that's good to know.
 

Ollie Krause

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Feb 26, 2020
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Hello Ollie,

wow 24lbs thats good. For your reference the skylite as seen here in 4130 (not including welds) is 31lbs. There are a few sacrificial tubes in there that will be removed, but the welds may take that back up. So if you don't mind my asking what tubing size is your fuselage made with and will you do an FEA to verify its strong enough?

View attachment 96277
We're currently planning on using 1"x0.035" 6061 T6 and hope to be able to verify it's strength with FEA before we begin construction. Our physics team is currently super busy with optimizing the weight and drag of our wing support struts and doing some CFD simulations on our wing but the fuselage truss calculations are next on their agenda. If you like, you can view, download, and copy our latest designs from our public Onshape document. We'll also be open sourcing all of our work when complete.
 

addicted2climbing

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We're currently planning on using 1"x0.035" 6061 T6 and hope to be able to verify it's strength with FEA before we begin construction. Our physics team is currently super busy with optimizing the weight and drag of our wing support struts and doing some CFD simulations on our wing but the fuselage truss calculations are next on their agenda. If you like, you can view, download, and copy our latest designs from our public Onshape document. We'll also be open sourcing all of our work when complete.
Hello Ollie,

Wow sounds like an awesome project. Now before your team spends all its time squeezing that last few percent of efficiency in CFD you might remind them that this will be a draggy airframe buy its UL nature and you may be spending too much time on aspects that are not critical for this type of airplane and redirect those resources to more important aspects like the FEA. Now if it were a composite streamlined aircraft than yes it makes sense but for this likely not much.
 

addicted2climbing

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We're currently planning on using 1"x0.035" 6061 T6 and hope to be able to verify it's strength with FEA before we begin construction. Our physics team is currently super busy with optimizing the weight and drag of our wing support struts and doing some CFD simulations on our wing but the fuselage truss calculations are next on their agenda. If you like, you can view, download, and copy our latest designs from our public Onshape document. We'll also be open sourcing all of our work when complete.
Ollie,

I just had a look at your onshape CAD model. One thing I noticed is you have two huge cross braces that would block the entry for the pilot. You may want to designate a side to add a door or at the very least an area with lower cross tubes for pilot access. On the right side of the cockpit area of the skylite frame you will see a qroup of tubes forming an inverted trapezoid shape. after welding the upper tube is cut away leaving a low spot for the pilot to enter. Also this area can be built back up with a folding door similar to a J3 Cub.

Other than this and the gusset issue you have with the off plane clusters this looks great.

My previous company tried to switch us over to Onshape and a fought it like the plague. Been using Solidworks for far too long to start over now. However, now that I am self employed and paying for my own seat of SW, Onshape is a looking a bit more attractive. Dark Aero is using it as well on their aircraft with great results. We eventually passed on it as there were not enough specialty plugins for what we were doing.

Marc
 

Ollie Krause

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103
I apologize if you have already addressed this, but how have you defined the aerodynamic loads?


BJC
Sorry do you mean loads for the fuselage, wing, or both? We've been mostly designing things using a conceptual approach and basing things off similar aircraft so far and we're still in the process of mastering all the calculations that go into verifying the safety of the design. We were worried if we started to get too deep into the nitty gritty calculations first, we'd end up calculating a lot of designs that we wouldn't end up using and it would be more efficient to take a TLAR approach and then refine it after we have a full draft. To make it clear, we won't even order parts until we've had at least a couple engineers look it over and we feel comfortable with the validity of all our equations. With that said, here's what we have done so far. I'm also just a CAD junkie and I'm not super involved with the work of our Physics team so I might have left something out. I'll have them chip in here though.

1) We calculated maximum upwards wing loading based on a 45 degree maximum bank angle
3) Drag/shear forces on the wing were calculated using CFD
4) Lift distribution along the wing determined using the Schrenk Approximation and then verified with CFD

Once we have our truss layout finalized, we'll calculate landing loads and verify the column buckling strength of all our beams. We also haven't taken into account any aerodynamic loading on the fuselage itself which I would imagine is quite important. If there's any resources for aerodynamic loading you suggest we study, it would be greatly appreciated if you could point us in the right direction. Also, though we have some numbers in terms of what the expected maximum aerodynamic loading will be on the wing, we are struggling when it comes to finding standard safety factors. Part 25 has some great information on this but I'm not sure how much of it can be applied to ultralight design as transport aircraft are a whole different category all together. Is there somewhere where we can find loading and safety factor standards? Thanks again for all the help.
 

Ollie Krause

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Feb 26, 2020
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Ollie,

I just had a look at your onshape CAD model. One thing I noticed is you have two huge cross braces that would block the entry for the pilot. You may want to designate a side to add a door or at the very least an area with lower cross tubes for pilot access. On the right side of the cockpit area of the skylite frame you will see a qroup of tubes forming an inverted trapezoid shape. after welding the upper tube is cut away leaving a low spot for the pilot to enter. Also this area can be built back up with a folding door similar to a J3 Cub.

Other than this and the gusset issue you have with the off plane clusters this looks great.

My previous company tried to switch us over to Onshape and a fought it like the plague. Been using Solidworks for far too long to start over now. However, now that I am self employed and paying for my own seat of SW, Onshape is a looking a bit more attractive. Dark Aero is using it as well on their aircraft with great results. We eventually passed on it as there were not enough specialty plugins for what we were doing.

Marc
Thanks for the advice! We totally didn't take the door placement into consideration. I'll go ahead and mock up a Skylite style access hole.

Yeah Onshape is definitely the younger sibling to Solidworks and lacks some critical features. I'm not sure what you're using Solidworks for (commercial or personal), but I think the EAA offers free hobbyist licenses to all of its members. I also know a couple people who use the free Onshape license for commercial purposes and Onshape doesn't seem to care too much as long as you don't mind your designs being public.
 

rv7charlie

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That low wing looks pretty clever, I wonder if it has any Kolb connection.
Let's hope not. The Kolbs have strut braced wings; removing the strut from Kolb-sized components would be a death sentence.

Jim Bede - designed a/c (BD4, BD5, Grumman Yankee, etc) would be closer, but without a hinged joint wing fold. I'd *really* want input from a qualified aero engineer on what's visible in the pics.
 

WBNH

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Portsmouth, NH
The Kolb Laser had a similar cantilever and folding wing...didn't get in to production though. Though the spar carrythrough didn't maintain the same large diameter tube as the outer wing panels.

SNF98__3_378.jpg



I'd be interested in seeing how the spar carrythrough is attached to the fuselage in the unnamed facebook plane...can't see much in the pics above.
 

Bill-Higdon

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Salem, Oregon, USA
Let's hope not. The Kolbs have strut braced wings; removing the strut from Kolb-sized components would be a death sentence.

Jim Bede - designed a/c (BD4, BD5, Grumman Yankee, etc) would be closer, but without a hinged joint wing fold. I'd *really* want input from a qualified aero engineer on what's visible in the pics.
I was thinking Texas Parasol meets BD-1 with a little "Fighter Ultralight" thrown in
 

WonderousMountain

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Clatsop, Or
My mind is on the A-B Scud II

Not thinking about Aluminum tube, but
Reworked the wing under the original 100
Ft^2, span 40ft parameter and my Cranked
planeform. Then another 26.67ft varient if
using a sustainor engine comes to 80ft^2.

Changing the center section to an arch, to
Make the pilot appear less tucked inside. I
like the body, interchangible tail feathers &
ChromeMoly parasol spaceframe. Slingsby
Petrel lets more light through the wings.

Sincerely,
CK LuPii
 

Gregory Perkins

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May 25, 2019
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Location
Atlanta
Are those college kids still building their tube frame T&G plane ? It is a shame no one ever pointed them to some of the inovative ideas of the very first AL tube builders of such planes as the Australian Scout in 1975, the Volmer Jensen VJ-24 , the DSK Nomad and the Weedhopper etc. These guys predated Graham Lee and Baslee by a long shot.
 

Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
Please provide some more detailed information on the structure of these early aluminum tube and gusset airplanes - I for one would like to learn more about them. I clearly remember the DSK airplane advertisements in Soaring, PM, and other magazines, but have never seen one in person.
 
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