"SkyWing" hybrid wing body ultralight

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
Do I understand what you are thinking?

The PVC pipes are to connect the edges of the foam together? Won't you still have the problem of the loads going through the foam? The foam itself is acting as the spar?

Why not post a picture? Just a quick sketch would do. Better yet, a photo.
Hi, and thanks for the interest! I'm really happy to see the helpful positive help coming in at last. ;=]

I must Draw my SkySled concept and glue some prototype pieces together to show y'all puzackly what I think.
But, in brief, think of a reversed Facetmobile where the fabric cover is replaced by a Styrofoam XPS brand air frame/fuselage and all of the interior trussed aluminum tube stress-distribution network is GONE, replaced by a few Styrofoam shear partitions. That's monocogue . Hopefully cheeper, easier and stronger and lighter, as Burt Rutan claims. [I bought his book] We'll see.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,075
Location
US
So, if the (unfaced, non-sandwich) XPS foam is what is being counted on to perform structurally as a monocoque, why put heavy PVC at the edges of the panels? Just cut angles properly at the edges of the foam and glue the foam together directly. That saves weight and money. Since the shear strength of the foam at the glue line (whether it is XPS-to-PVC or XPS-to-XPS) will be the failure point, there's nothing gained by including the PVC. As a bonus, without the PVC lances to impale the occupant, things may go better when it comes apart.
 

Doran Jaffas

Well-Known Member
Joined
Jun 25, 2019
Messages
428
Okay I heard two things here plus something else earlier. During this read I heard that he was only going to fly a couple of feet above the water as a tow behind vehicle which frankly does sound exciting and fun. It beats an inner tube in many ways. Also if something comes apart it's no more exciting than crashing on water skis that appeared to me to be Mach 1 but I'm sure was much slower than that. Personal experience. But! He has said that he intends to fly it up to 2000 ft like a real airplane.. I fly my real airplanes much higher than that but anything over 50 ft is enough to get one severely hurt if not severely dead. I know he said that he is not 17 but age has nothing to do with experience level in this case. There are designs out there with proven materials that though they may be a little more expensive they are cheaper in the long run if they last not to mention the fact that they are less likely to fail and spare your body unnecessary damage and possibly no place for your Soul and Spirit to live.
No one that I have seen is trying to be critical of his idea. I would like to see a sketch of it myself and some drawings of his construction concept with the materials used. Also several have put in how to load test it and then put the numbers out for us to see and I don't think that is unreasonable at all. Should we support him in his idea? Yes to a degree and no to a degree. If he is really looking for just a cheaply built inexpensive aircraft and he really doesn't have any knowledge of how to do that and people on this forum do then he needs to listen. If he is looking to only take it a couple of feet off the water then go for it and videotape it please. I would love to see it and see the concept but not at 2000 ft without proving the numbers and without the acknowledgment that others on here do have experience in aircraft construction and don't just do it from hearsay because this is what works so this is how I'm going to do it although there is a time and place for that. All of us experiment. That's what this wonderful thing we call aviation in the experimental amateur built category is about. Very few of us take unnecessary risks with our life and limb intending to make our families fatherless or husbandless or brother or sisterless. This is serious business here and if it is just a troll that he is trying to get an argument going then we need to put this to bed but again him showing us his basic design along with properly done stress analysis would go a very very long way. I will not post on this subject again because I just think it's gotten out of hand but I do intend to read some more on it and look for his drawings and stress analysis.
 
Last edited:

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
This wingless aircraft is an ultralight I'm designing to build with 2" blue styrofoam and 1 1/2" PVC pipe for wing spars. Power will be a 22hp Briggs 4-stroke gas engine. meeceblog.wordpress.com
Here's a study model of the SkySled composite materials design. I might call it the FacetUltra since, like the genius Facetmobile, it has no conventional 'wings.' This weighs 15 pounds and costs $75 in parts. It is one of three 'spars' the design will require. [the 'spars' ARE the wings] The spars would have 2" foam glued between them to make the skin/frame/fuselage/wing whew, a new aeronautical phrase is born. Lifting body, for short. Think 'monocoque.' I think it is easier, cheaper and lighter than making a conventional hard-spar-with-many-ribs wing.
Easier still would be to carve this PVC tube frame out of 2" Dow branded Styrofoam XPS insulation sheet which costs $30 up north but $75 way down in Key West due to shipping costs one small supplier.
SO, my next development plan is to adapt this frame to XPS Styrofoam and distributing the point stresses with carbon tape! I got a roll of it from Amazon and it is affordable for its amazing strength per foot.
Keep looking up and you'll GO up! ;=]
 

Attachments

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
So, if the (unfaced, non-sandwich) XPS foam is what is being counted on to perform structurally as a monocoque, why put heavy PVC at the edges of the panels? Just cut angles properly at the edges of the foam and glue the foam together directly. That saves weight and money. Since the shear strength of the foam at the glue line (whether it is XPS-to-PVC or XPS-to-XPS) will be the failure point, there's nothing gained by including the PVC. As a bonus, without the PVC lances to impale the occupant, things may go better when it comes apart.
RESEARCH UPDATE...
!!!! Excellent !!! I found pvc cement joints too brittle and cracking easily with sideways bending stress so I will not use them as frame members/support web whatever.
But for now I think I will try 1 1/2" PVC tubing as merely connectors between adjacent facets rather than try to glue foam sheet to foam sheet edgeways. Yuch. There has to be a wide fillet at the seam to grab more surface area of the foam rather the just the inside edges of the sheets. 1 1/2" tubes placed between board edges provides grooves in which to dump a thick bead of polyurethane adhesive and then spread it out to make an inch-wide fillet on both sides of the tube so there is more gripping area for the glue.
Construction adhesive, $4 a caulking gun tube. ;=] Beats epoxy expense.
You may be right about gluing foam boards directly together. Any ideas on how to mechanically strengthen such direct glue seams with a light weight material? The seam needs 'caps' on both sides I believe. could use fiberglass or even carbon tape for that but am having trouble visualizing the steps in the application process.. ???? I think I could start with an "S" shaped tape through the seam and epoxied down and then apply a wide ply of glass across the taped seam. Hard to describe but I'm starting to see how to do it. Thanks for the support ;=]
 

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
Here's a sketch of the current seam bonding method. It's easy to do with a caulking gun. But the tubes are heavier than glass tape i suspect.
I'd like to figure a neat and simple way to bond foam board with glass and epoxy.
 

Attachments

Aesquire

Well-Known Member
Joined
Jul 28, 2014
Messages
2,690
Location
Rochester, NY, USA
Wide bandages? ( fillet is in the inside of an angle ) of glue won't work. The glue will either crack when bending, or when the foam fails, you'll have mangled "H" shapes of glue with foam stuck to them, possibly a more or less solid rectangle of foam with the H inside. Because the edge of the glue will be a stress concentration line the foam will snap on. If there's a pipe in the middle that gives a shape my keyboard won't make. :)

A scarf joint? In wood projects, instead of a 90 degree butt join, which is the shortest area possible to blue parts together, cut the foam at an arbitrary angle so you have a long, large area to glue.

Scarf joint - Wikipedia

For reinforcement, consider tapes at diagonal to the span, crossing each other.



Here's a discussion on bonding foam. Testing XPS foam for epoxy adhesion/bonding

Half the work in foam I've done is assisting in a Quickie build. That uses the "Rutan" style construction, which is actually derived from sailplane repair techniques. Also called Moldless composites.

You carve the foam into the shape you want ( minus the fiberglass ) and then, brush with a very thin layer of exoxy resin, lay fiberglass cloth ( at the angles specified in the plans, # of layers, etc. ) on and brush epoxy on, repeat...

For wing sections we used a hot wire, a nichrome wire stretched on a big wide H of wood, like a cartoon Frame saw, see #21 55 Different Types of Saws And Their Uses (With Pictures) The wire was connected to an old toy train set transformer, and tightens and loosens as it heats & cools. The glued together slab of foam then had airfoil shaped outlines in plywood glued and nailed to each end, the hot wire saw operated by a human at each end then plunge cut to the outline and follow the outline around. It's best to mark off 1 or 2 inch marks with numbers on both outline boards so the 2 operators can coordinate the slow cut "almost to 6" "about a half inch to 23 , slow down" etc. Then sanding, glass application, sanding, sanding, sanding, ...... OOPs, lost in dusty memories, sorry. :)

The foam in this case acts like ribs, one big continuous one. There are lighter methods but for a minimum amount of tooling, no big molds etc. It is well proven tech. Of course this isn't even a beginner guide.

And you don't want to do a big composite project. Check out the Mike Arnold videos on how to do it right.

g

autocorrect is being mean to me today, excuse errors, please.. It's Never Duck You.
 

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
Wide bandages? ( fillet is in the inside of an angle ) of glue won't work. The glue will either crack when bending, or when the foam fails, you'll have mangled "H" shapes of glue with foam stuck to them, possibly a more or less solid rectangle of foam with the H inside. Because the edge of the glue will be a stress concentration line the foam will snap on. If there's a pipe in the middle that gives a shape my keyboard won't make. :)

A scarf joint? In wood projects, instead of a 90 degree butt join, which is the shortest area possible to blue parts together, cut the foam at an arbitrary angle so you have a long, large area to glue.

Scarf joint - Wikipedia

For reinforcement, consider tapes at diagonal to the span, crossing each other.



Here's a discussion on bonding foam. Testing XPS foam for epoxy adhesion/bonding

Half the work in foam I've done is assisting in a Quickie build. That uses the "Rutan" style construction, which is actually derived from sailplane repair techniques. Also called Moldless composites.

You carve the foam into the shape you want ( minus the fiberglass ) and then, brush with a very thin layer of exoxy resin, lay fiberglass cloth ( at the angles specified in the plans, # of layers, etc. ) on and brush epoxy on, repeat...

For wing sections we used a hot wire, a nichrome wire stretched on a big wide H of wood, like a cartoon Frame saw, see #21 55 Different Types of Saws And Their Uses (With Pictures) The wire was connected to an old toy train set transformer, and tightens and loosens as it heats & cools. The glued together slab of foam then had airfoil shaped outlines in plywood glued and nailed to each end, the hot wire saw operated by a human at each end then plunge cut to the outline and follow the outline around. It's best to mark off 1 or 2 inch marks with numbers on both outline boards so the 2 operators can coordinate the slow cut "almost to 6" "about a half inch to 23 , slow down" etc. Then sanding, glass application, sanding, sanding, sanding, ...... OOPs, lost in dusty memories, sorry. :)

The foam in this case acts like ribs, one big continuous one. There are lighter methods but for a minimum amount of tooling, no big molds etc. It is well proven tech. Of course this isn't even a beginner guide.

And you don't want to do a big composite project. Check out the Mike Arnold videos on how to do it right.

g

autocorrect is being mean to me today, excuse errors, please.. It's Never Duck You.
Excellent advice!!!
Next I'll try gluing the foam board edges together with construction adhesive thick glue and laying a 4" wide Kevlar or carbon or glass ?? tape cap along the seam and epoxying it down.
I have Rutan's composite manual and its a nice one for resin techniques.
I also have Wainfan's airfoil manual and like it a lot even tho it doesnt include his thoughts on lifting body aerodynamics.
His FMX5 version of the Facetmobile was to have been a honeycombed foamy but he didn't make one, just designed one for the military. My big SkySled wing-section type of wingless UltraLight airplane is the simplest lifting body of all and the airfoiled-fuselage form has been well-proven in flight amply as in the 1978 Popular Science wingless plane. It didn't even need rudders! 8=0 Can you spot any design errors in the photo? Maybe the propeller cutout in the center of the lifting body? Dunno, maybe it's just me.
 

Attachments

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,727
Location
Marion, Ohio
Why not wrap the kevlar, carbon, or glass tape around the edges of the XPS panels, with epoxy, instead of using the PVC pipe?

That would be lighter, I think, than the PVC pipe, and is a well known technique with a proven track record.

While you are at it, also run some pultruded carbon rods lengthwise along the joint.
 

poormansairforce

Well-Known Member
Joined
Mar 28, 2017
Messages
1,111
Location
Just an Ohioan
The cheapest and lightest glue ever for XPS foam is some thinner and a spray gun and use that to very lightly mist the thinner on to the foam, let it get a little sticky and put the two pieces together for an instant and permanent bond. I learned this when I was laminating foam sheets for the floats on a pontoon boat as a teenager.
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,196
Location
Clatsop, Or
Here's a study model of the SkySled composite materials design. I might call it the FacetUltra since, like the genius Facetmobile, it has no conventional 'wings.' This weighs 15 pounds and costs $75 in parts. It is one of three 'spars' the design will require. [the 'spars' ARE the wings] ...

Keep looking up and you'll GO up! ;=]
Ask him,
B. Wainfan is a member here.
 

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
The cheapest and lightest glue ever for XPS foam is some thinner and a spray gun and use that to very lightly mist the thinner on to the foam, let it get a little sticky and put the two pieces together for an instant and permanent bond. I learned this when I was laminating foam sheets for the floats on a pontoon boat as a teenager.
!!!! Excellent tip! I tried it and it gives the XPS foam a thin little shell of a skin that has melted into the XPS board. Much tougher than the normal plain foam surface!!
I don't know where to best post design updates so here goes; this is sorta like Rutan did it on his wings. Fiberglass takes the place of my old beloved PVC connector tubes. ;=]
I found that Tyvek house wrap nylon paper tightly binds to the soft surface XPS with cheeep casein glue and gives it a grippable, spread-out surface at the seams to combat stress-separation. It is an easier, more predictable method than brushing on a light coat of acetone to melt a skin into the foam surface. I'll do more testing to make sure.
As shown below, I don't want to angle-cut the board edges where they fit together at angles. Tooo dicey. I prefer to retain the perfect factory edges and make the angle with wet fiberglass cloth. Comments?
 

Attachments

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,075
Location
US
As shown below, I don't want to angle-cut the board edges where they fit together at angles. Tooo dicey. I prefer to retain the perfect factory edges and make the angle with wet fiberglass cloth. Comments?
If there's any compression loading on that unsupported fiberglass "cap" section, I suspect it will buckle and fold very readily. Foam in that gap would help prevent that (if the skin stays stuck to the foam).
Regarding the described novel skins of these panels: There's no way to even estimate their strength by calculation, only testing would indicate how they behave. At least at that time.
 

Allen

Well-Known Member
Joined
Jun 3, 2010
Messages
60
Location
Key West
If there's any compression loading on that unsupported fiberglass "cap" section, I suspect it will buckle and fold very readily. Foam in that gap would help prevent that (if the skin stays stuck to the foam).
Regarding the described novel skins of these panels: There's no way to even estimate their strength by calculation, only testing would indicate how they behave. At least at that time.
Hmmm, You see the 'U' connector with serifs? That is the shape of most rural highway speed limit sign poles and boy that shape is stiffffff.
[plus i dont even wanna try to cut a 6' strip of stryofoam accurately enough to fit snug inside the connector piece ;=] [crosses fingers. will test it carefully]
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
8,787
Location
KWHP, Los Angeles CA, USA
If there's any compression loading on that unsupported fiberglass "cap" section, I suspect it will buckle and fold very readily.
He doesn't care if it supports his weight safely without buckling. He cares if it's cheeeep.

The cost of the pilot is no concern here.

May I suggest the Bachem BA-349 and Yokosuka MXY-7 as relevant case studies here?
 
Top