CarbonLight, the Carbon Fiber Wing Build.

Hi all, wanted to use this tread as a place holder for my CarbonLight(tm) wing build... the name is just for fun


So far calculations for the parts I have been designing as are follows:

Calculated wight for Front+Rear Spar = ~5.8Kg or ~13 LBS (Design limit is 10Gs) I still have to build this completely, I think it will come out closer to 7kg or ~15lbs.
Calculated wight for Full Size Ribs = ~62g ~2.2oz (Design limit is 10Gs)
Calculated weight for ailerons = ~420g or ~.9lbs

So, 15+(16*2.2)+.9 comes out to roughly 18.2 lbs, add the rest of the HW... some where close to 6.4lbs and you get a 24.6lbs, add some fabric and and 12 lbs gas tanks and you are in the 48 lbs fully finished wing.


The airfoil is of my own design, I am still tweaking the LE to get to to fly just a bit faster, but with a L/D of 90, it should be close to flying a Cub with ABW at 120 mph cruise
CL_Max without flaps is at 1.75 @ AoA at 16º and Re of 800K (17mph). Flaps at 38º gives me a Cl_Max of 2.97 @ AoA 12º and same Re 800K, will it fly at that speed, no, but it sure can get close to that!!! :roll::roll::roll:

Here is an insight in how it will look!



Next follow-up will be the Spars at their weight in. I am still waiting for lot's of bits to come in to get the full sets built and analysed.
Might get a picture of the Test Ribs in place, I am building both a USA 35B Mod and my own airfoil. Just ran out of CF so will order that, if that shipment comes first I will port a picture of the stress test of the rib, that is hanging 80kg on the rib... I weight in at 90kg!!! all that on 2.2oz of material, should be cool to get it right the first time

Ok, got to go eat!

Spain, will the cord and span be identical to stock Cub? Round tip or square? Flap and aileron span?

Cool project!

Not a carbon-skinned structure?

Wow! cant wait to see some photo's I'm playing with a rib now. I already have the leading edge, trailing edge and fuel tanks done. just finishing with my first flap. 4' section of leading edge 20 OZ, 18 gallon tank with fittings 5# 3 OZ. I would love to see what you are doing maybe we can help each other out.

Thanks Dave,

Here is my thinking, when you expose all that skin area, you need lots of primer and paint to properly cover it up from the heat and not get into delimitation because of UV decay of the resin. So the cost of the mold, the fiber, wight of resin, plus the weight of the primer and paint really convinced me this was not the way to for my wing.

Yes, chord will be 63 in, depending on how the upcoming wind test go, I will decide if flap or Gurney flaps.

I was originally thinking of going for Horner Wing tips, but after a conversation with an aerodynamic wiz (active F1 co-designer in Switzerland ) , I am leaning into testing a square (more like rectangular) wingtip fence, with a 20% top, 35% bottom extension from the thickest part of airfoil. I have to do some experimentation in CFD to see how the flow out side the wing will flow to and fro to see if this will weaken the wing tip vortex and reduce flight induce drag, I want those tips lifting.

I've also tested the airfoil with slats, and considered dynamic slats, but I still had to go beyond the 12º AoA to gain those benefits. And yes, Cl_max does increase dramatically, but at or bellow 12º AoA, it was roughly the same, thus scrap the idea of going that rout.

I was going to post this on another post, but since I am here I thought I share it with you all. I have tested the USA 35B Mod airfoil in the wind tunnel, one version is similar to what I have seem, (A) build a slat to add to a cub wing, and (B) one is take the Clark Y data to build a slat on the USA 35B airfoil, sort of what Dakota does.

Some preliminary values:

(A) increasing the chord about 6% (I used Lit'l Cub pictures to gestimate that value) wind tunnel data showed that Cl_Max incased from about 10 ª to roughly at about 15º AoA , L/D ratio dropped, meaning it was more draggy and Cl_max dropped about 3-5% at AoA below that. Meaning that although this wing will make the airplane slow down, there is a sudden burst in the laminar separation bubble, so you really don't gain much, much like you loose some on the flair. (Did not take percentage of the drag differences slar/no slat.)

(B) While keeping the chord the same, there was less than 2% gain in drag and the Cl_Max was maintained the same up until the10º to 12º AoA where there is an increase in Cl_max. Substantial increase of about 20% in Cl_max begun at 16º+ AoA.

Comparing the two, (B) should perform slightly better for STOL, but this is more of an educated guess than empirical data as a Doctorate student kicked me out of the wind tunnel just arriving and gave me about 20 min access to the facilities, so I was not able to do the test and take down more data.

In model A, slat where covered in the model since it differed somewhat from one model to the other at same Re.
Re values where between 600K and 1.5M so looking at performance at slowest of speeds, from say 15mph to 38mph on my models.

I hope to build new models of the wings soon and redo the tests once more to get a more accurate values and share that with you all.

So, someone sent me an email to ask me how I came up with the airfoil, and that is a long story, but in part, I promised to share this publicly so here is a simple approach I took:

I looked at several airfoils, maybe too many to get them mixed up and list them here, but I started out with a NACA 63 series, and drew that up to full scale, Autocad first then printed that, I then took a protractor, and started to see when're on the geometry of the curves I could gain something, LE, chamber, thickness, I drew that up real size, the used a full scale transfer pad and took new values around the redrawn stations, used Autocad to smooth the spline, took that data and moved it to OpenFoam and XFoil to gain insight into my my changes, on the first iteration of this, the airfoil was so different that I could call it my own, I then repeated this several times until I got as smooth transition away from stall as possible. As expected, I lost L/D on the process, but I could keep the laminar separation bubble longer, or keep the airfoil from stalling. This has been a long an coming process, and I have received inputs from many people, including JimC that lead me to a path to reconsider substantially my airfoil all together which influenced LE and top geometry of the airfoil all together with one suggesting he gave me as an interesting airfoil.

So, I have one more thing to do to this airfoil and that is to run it through an algorithm to get it optimised and see how much difference there is against what I came up with...

Here is a comparison of some High Lift airfoils vs my own design, the think Hot-Pink is the JEMO-STOL 12-14 airfoil, USA 35B would be some what below the lowest CL performing foil benched marked here.

8856Charlie said:

Wow! cant wait to see some photo's I'm playing with a rib now. I already have the leading edge, trailing edge and fuel tanks done. just finishing with my first flap. 4' section of leading edge 20 OZ, 18 gallon tank with fittings 5# 3 OZ. I would love to see what you are doing maybe we can help each other out.

Click to expand...

Are you in AK? :???:

How many plies for your LE? Sound like it's heavy?
Is that your tank that came up recently on a post here? I don't know how much aluminium tanks weigh, if it's yours, looks great, did you ballon that then infused? that's what it looked like to me.
I sent lowrider and PM a while back to look into the stuff that Jaguar was using to hold their new sports car together, I was considering using that stuff to bond my tanks, plus rivets.
BTW, where does one get the neck of the tank, where you cap the tank?

Spain

GREAT stuff. I will be following closely. Thank you for posting and for the innovation. AWESOME!!!!!

Bill

Spain:

Great that you are experimenting. The only caution I would put forth from years of experience with XFoil is look at the airfoil with the boundary layer tripped (no laminar). If it behaves then, you have a good airfoil. If you see anomalies in the data , keep looking. Also, trailing edge thickness is very powerful. You can't build a zero thickness TE.

Good luck!

sbaber said:

Spain:

Great that you are experimenting. ......... look at the airfoil with the boundary layer tripped (no laminar). If it behaves then, you have a good airfoil. If you see anomalies in the data , keep looking. Also, trailing edge thickness is very powerful. You can't build a zero thickness TE.

Good luck!

Click to expand...

..and what about bugs.

...and dirt on the bottom of the wing from the muddy tires.


The reason I asked about the carbon skin: it can maintain accuracy of the airfoil........and ribs covered with fabric cannot.

...also.....and I may be bursting a bubble here..................carbon parts applied to a structure designed in 1939(?) to be built in aluminum (Cub Wing) may not be an efficient use of carbon VS a structure designed to utilize the properties of carbon and resin.........I know you have thought of this Spain.

By the way. .......8856C is in Alaska.

Yes, there is no doubt that laminar flow is important, but this is where I put a lot of my effort in understanding how this airfoil would work.
Basically I used Xfoil and OpenFoam CFD to get a good approximation of the 2D and 3D performance of the wing, I used NCrit 2.3 and 2.1 back and forth (lower = more turbulent) as I have noticed that with the NACA data, your approximation of theoretical to wind tunnel data is much closer. If anyone has ever done wind tunnel testing (and my facilities are not state of the art like NASA) you still get variations on the test run and from the models themselves. For my models, I have used extremely thin hi weave polyester fabric to test it on my model 3D partial wing model (the blue stuff the car tunning people use.) This test dada seemed to concur with the CFD and XFoil test data as far as pressures and CL values within a 2-5% margin. The important thing was that have the characteristics I was looking to build into my airfoil. If you consider that some people are flying the Ribblet design, and he used the old Eppler code to validate his 2d airfoils, I feel quite confident that I am heading on the right direction. I will still build a scaled model of the full wing, put it on top of my was and run further test on it just to make sure I have the pressure distribution correct and also test my wing tip fence.

If you look at the airfoil, I have moved the camber substantially towards the TE to lower the rear pressure of the airflow and also adjusted the LE radius to continue to force high pressure to the lower part of the airfoil (8% to about 40%), this allows for the laminar flow bubble to stick longer on the airfoil. On wind tunnel test, you get even greater results and at about 22º AoA does the L/D start to become critical and you see the flow bubble beginning to encroach forward. It's really cool to play with all this stuff and see how the downwash energised the TE vortex to continue to have lift until about 28º AoA. This is because of the high camber moved further aft of 50% of chord.

Dave, you can measure the thinness of your laminar flow bubble with some Trig, but there are ways that give you good enough approximation to feel confident that this is not a critical laminar flow airfoil, so yes you will have some anomalies on the wing with fabric covering, but I have been researching this build and the use on these materials for soaring applications and critical laminar flow airfoils, so I feel quite confident on this good approach for flying at 20 mph to about 120 mph (and you can go a little faster if you trim downwards... no need to mod your thrust line )

..also.....and I may be bursting a bubble here..................carbon parts applied to a structure designed in 1939(?) to be built in aluminum (Cub Wing) may not be an efficient use of carbon VS a structure designed to utilize the properties of carbon and resin.........I know you have thought of this Spain.

Click to expand...

I also agree Dave, and I have commented before that what I call the "black metal" approach of CF is the wrong way to go. I am however building a set of wings here, and things like TE (it performs well to about 3mm not easily viewed in the image I posted, and to build it within 1mm in CF is easily achievable) is where CF plays well with this design, else it would be useless.

As far as approaches, In my design I have debated whether to build a D spar design than a tradition dual spar design. I considered the placement of the fuel tanks on the D spar also, but I did not like the moments generated by this approach, creating greater demand on the lift of the tail, so I moved away from that. I could probably get ways with a 25lb wing in the end if I did a little more refinement, but I wanted to keep the roughness of the back county in my design, that is why I did it this way. If you look at what happens when you bond the LE to the Ribs on my design, you are really gaining so much rigidity on the wing, that you will not require drag, anti drag wires or truss in the wing. I add them as a safety measure of the toughness of the wing, but you don't need most of it. The TE part of the Rib for example (aft of the Rear spar) that part alone was able to withstand 65kg of weight with no apparent deformation on the part. Considering it weight less than 30g that is an amazing feat. I have since change some of the laminates to eliminate weight and cost.

Understanding composites is not easy, but once you do, it is fun! there are still some issues to resolve around joints where metal is still king, put you can get away with a lot of alternate solution in the end, and they don't look like anything you would have done in metal in the first place. I calculate every laminate I try to build, and see that it meets my design goal beforehand, then test to validate my own assumptions. That is the Fun part of the build for me really... the rest is just putting it into practice and building. I thought it was a lot tougher to blank your head sort-of-peak to begin thinking in a new way how to solve some building hurdles with these materials.

If you consider the cub frame for example, I have come up (I did not come up with it, just borrowed the building principle to apply it for this problem) with a design where you can have a full carbon airframe, keep the traditional look of the cub, but cut build times of such a structure to nearly 3 days and be a lot tougher than Chromoly, without the issues of corrosion... that will come in the end I think, and the good thing is it will look like a cub instead of a Glassiar 2+2, performance would be on par of the cub with some performance gained in overall all weight reduction, but noting spectacular on that front. Thats is another project that will have to wait a little while though...

BTW, constructive criticism is always an opportunity to learn, so shoot way I like to get as many POV as possible in considering alternatives.

8856Charlie said:

Wow! cant wait to see some photo's I'm playing with a rib now. I already have the leading edge, trailing edge and fuel tanks done. just finishing with my first flap. 4' section of leading edge 20 OZ, 18 gallon tank with fittings 5# 3 OZ. I would love to see what you are doing maybe we can help each other out.

Click to expand...

Charly, How are you building the LE? How many plys of CF? I am using 12K 320g tilwill 45º with some Uni 12K 300g and 600g tape to reinforce certain areas. I am infusing most of it, although I had been using my own prepreg to build the ribs, but I originally thought of making a 3 piece mold for my ribs and put in pressure. That was very light but shear did not work well. I made a simple beam shape that was build in a two process cure, where I would make the flange then bond the web that was partially cured also, I would put tension not the web by tensioning it and then cure it. It was ultra light, but it would fail under shear, and ribs work under that load most of the time. For a spar it would be OK, and even lighter (geodesic beam) but very complex to build for me.

Now I am hopping to get some moulding high heat silicon to build my new moulds with a heat plate to heat the part while in vacuum to improve cure and reduce weight a bit.
BTW, I met some french guys on their way to Africa on a PA-18, So I got a good look at your belly pod, nice work... I have plans to build one but that is way off in the distant future.

Spaincub, with your computer skills, could you show us "Huh" guys a drawing with a cub airfoil layed over the top of the JEMO-STOL one or vice versa of the one you have in the graph above? Would be neat to see.

USA35B_Piper_Mod Red, JEMO STOL 11-30 JEMO STOL 12-14

Here you go, you could see the difference between USA-35B MOD used by piper in red, and a starting point for my development in blue and light blue the final version of the airfoil.

Spain, thanks for the reply. I see that this is a FUN EXCERSIZE for you, with modest expectations of weight loss and performance gain.

I expect others will read your ideas and think "...why the heck bother with all that?.."

Hopefully they will understand that you are HAVING FUN with the PROCESS, and enjoy spending your time.

I have a thought for a Cub-looking fuselage of composite construction. The build process would be about 3 days to completion, Versus like-forever for a chromoly stucture. Still, I am a TLAR (that looks about right) composites engineer, so the passenger area will still be steel-tube construction.

I want to hear about your carbon cub fuselage.

Spain cub, the leading edges are a simple hand layed squeegeed laminate, just two layers of plain weave 5.8 OZ carbon with a hetron vinalester resin. very basic and simple. saves right at 10# per set of wings. The tank is done on a split male mold the two parts are made, fittings bonded on (aircraft spruce for Weld on fittings, Stoddards for threaded filler neck) then the two halves bonded together. Again just a very simple fabrication. Most of the parts I'm building are vacuum bagged I have done some infusion but I have had problems while introducing core into the structure and on very thin laminations, still playing with it. I have also been dreaming of a all carbon/core airframe for a cub, know it can be done just haven't had the time/$$$ to try it yet. Keep up the great info and engineering I so wish we had a wind tunnel in Alaska to use it would be a lot better than our bolt in on and try it test method!!!!

Hi. Can all of you just stop posting opinions and give me drawings? LOL
I am in the process of building a microlight with STOL performance.
I need Fowler flaps and automatic retracting leading edge slats.
The end! :~)

8856Charlie said:

Spain cub, the leading edges are a simple hand layed squeegeed laminate, just two layers of plain weave 5.8 OZ carbon with a hetron vinalester resin. very basic and simple. saves right at 10# per set of wings. The tank is done on a split male mold the two parts are made, fittings bonded on (aircraft spruce for Weld on fittings, Stoddards for threaded filler neck) then the two halves bonded together. Again just a very simple fabrication. Most of the parts I'm building are vacuum bagged I have done some infusion but I have had problems while introducing core into the structure and on very thin laminations, still playing with it. I have also been dreaming of a all carbon/core airframe for a cub, know it can be done just haven't had the time/$$$ to try it yet. Keep up the great info and engineering I so wish we had a wind tunnel in Alaska to use it would be a lot better than our bolt in on and try it test method!!!!

Click to expand...

Cool. So, how much do the LE eight on a Cub wing? I was considering doing a single 300g twill with a 100mm uni tape at the centre of radius, since I have the exact radius of my airfoil, I will create a plug for the LE and also use vinalester (local source.) To keep things constant, I will build a large box out of DM with several coats of primer on them to steam the LE while still on the mould. I have an epoxy I have to try that is is supposed to be flexible, I was considering that as an option for the LE.

I was making a small tube section of two ply 45º twill and 90º uni fabric for a strength test, used a aluminium tubbing, preperg both pieces of fabric, rolled it over the tubbing tight, then thinly warped it with plastic. I then placed the tubbing over the exit of a source of steam (steam was only flowing through the tubbing) and I was able to cure in about 4h. Cool part if that in this low heat, the AL tubbing expanded, and once it cooled it almost complete released the home made tubbing. These will be for a set of trusses used for the rib fabrication. I place it between a beam, put a rope over it and I was able to swing from it with out a problem, weight was something like 3.5g for tubbing, so I guess I can surely make the ribs form these no problem.

Cheeky, Can you share your plans with the rest of us? I am sure many here would be interested in such plans

For the rest,
I will be drawing up a set of plans based on the USA 35B Mod airfoil for a 63" chord with Slats. I should out perform at bolt on slat wing substantially while maintaining cruise performance! It will most probably not come even close tho my own design!!!! 8)
Sorry, but I have only calculated the rib based on a wood fabrication, if people are interested, I will share it on the user documentation section (if that is OK with SJ .

Dave Calkins said:

with modest expectations of weight loss and performance gain.

I expect others will read your ideas and think "...why the heck bother with all that?.."

Hopefully they will understand that you are HAVING FUN with the PROCESS, and enjoy spending your time.

Click to expand...

I said the enjoy that bit of the process the most, but I can assure you, my main motivation in weigh savings is nearly 40lbs per wing and performance? Well, if things go well, consider flying at low 20's mph at 4-10º AoA or cruise at a solid 120mph (may be more)... pull back on the gas and go 100ph and save a nearly a gallon/per-hour... yes, that is my modest calculations...

Cheeky, Can you share your plans with the rest of us? I am sure many here would be interested in such plans

LOL are you crazy? I am copying and applying what you guys are typing here :~
Just joking... I am developing something for the military.
It will remain my intellectual property design and us homebuilders will benefit from it I promise (if it works)...
I am bound by rules.

Sorry...I am a wood builder. If 3 ply was transparent I would have used it as a windscreen!
Carbon Fibre? pffttt too heavy and expensive... cannot tolerate vibration etc etc etc.

All I neeed is not to re-invent the wheel.. has someone got plans for me for the automatic fowler slats used on the mS Rallye or Helio Courier? Otherwise I wouls have to design it myself

This wing rib shape reminds a little of what your thinking. Also at 4.30 sortve some neat stuff.http://www.youtube.com/watch?v=H0YDyflDb-4

One more interesting one.http://www.youtube.com/watch?v=2geXBvpIE0ANo 2 more http://www.stolspeed.com/pegastol-wing

You are my hero !! you even posted a link with mentioned the Helio courier. You know your stuff dude!
Yes, I own a set of 701 plans, but it is just not efficient enough for me (great plane) and I love Chris Heinz....genius.
What bugs me is why he dropped the Auto Slats?
I have a NACA study where the slats are more effective with fowler flaps tucked and deployded in inlogical sequence.. baffled.

I just challenged my gyro engineer tonight that I will kick his ass with the same engine! lol .. ( I admitted that in wind and turbulence he will take me), but I will manufacture a competitive aircraft which will be almost half the price and will cruise faster, will get off the ground faster, land shorter and use less fuel.. challenge is on!

I am not a fan of flaperons either. (Results in reversed control under extreme settings) but I have to keep things under wraps for now.
Pieta .. in South Africa.

i would be interested in building that wing for my Cartesian cub , i don't know if you did some more work on t but i was planing on a very similar wing profile but yours seem even better , could you share some more info or a way to get in contact , that would be so neat to exchange info and build method .

so you are using tube spar ? i was thinking along the ling as D spar ,mid rib , and box style false spar , honeycomb sandwich greatly reduce the number of leading edge ribs and is very strong , i can't post pic and drawing her you have a e-mail i can show you some more detals?

flaymaniac said:

so you are using tube spar ? i was thinking along the ling as D spar ,mid rib , and box style false spar , honeycomb sandwich greatly reduce the number of leading edge ribs and is very strong , i can't post pic and drawing her you have a e-mail i can show you some more detals?

Click to expand...

flaymaniac,

Seems like you were asking me the question, so I will answer. No, I am not using a tube spar. The "tube" is just a mold for the carbon leading edge that is basically the same as a Piper leading edge, just made out of carbon. I have not built a carbon spar, to bond the leading edge to, yet. One small step at a time.

Jonny O

QUOTE=flaymaniac;728011]so you are using tube spar ? i was thinking along the ling as D spar ,mid rib , and box style false spar , honeycomb sandwich greatly reduce the number of leading edge ribs and is very strong , i can't post pic and drawing her you have a e-mail i can show you some more detals?[/QUOTE]




flaymaniac,

Seems like you were asking me the question, so I will answer. No, I am not using a tube spar. The "tube" is just a mold for the carbon leading edge that is basically the same as a Piper leading edge, just made out of carbon. I have not built a carbon spar, to bond the leading edge to, yet. One small step at a time.

Jonny O

Jonnyo said:

QUOTE=flaymaniac;728011]so you are using tube spar ? i was thinking along the ling as D spar ,mid rib , and box style false spar , honeycomb sandwich greatly reduce the number of leading edge ribs and is very strong , i can't post pic and drawing her you have a e-mail i can show you some more detals?

Click to expand...

flaymaniac,

Seems like you were asking me the question, so I will answer. No, I am not using a tube spar. The "tube" is just a mold for the carbon leading edge that is basically the same as a Piper leading edge, just made out of carbon. I have not built a carbon spar, to bond the leading edge to, yet. One small step at a time.

Jonny O[/QUOTE]

Piper leading edge is more like a U shape how are you planing on making a leading edge with a tube , or it's just a test for molding, much expensive test , and it need to be cure at 250 or more or it will crack when ironing the oratex or poly skin it's been a problem for most low temp leading edge available on the market , that's the reason i built a poor men autoclave out of a old propane tank, low cured phenolic resin is to heavy ( 45% to 40%) compare to( 38% to 34%) vacuum and pressure cured at 350 for 4 hours, and fragile to uv and temp change, or i am missing something you have not mention yet .

mdf is a great mold mat and once mold form is achieved i cover wit thin on aluminium sheeting adder wit silicone it's cheep and do a nice finish , but my favorite is to used a foam plug and oven cure it once un molded .

beside i just answering to be polite, i was more interested in talking to Jose Morales but i think he is just to occupied some where else , so l will just used a tested wing profile NACA 4 series with 8% back camber at 70% like i was planing.

so il just keep building my wing , good luck to you and your work in progress, hope it turn out like you wish.

Any updates on this carbon wing and fuselage that has been getting talked about. I am currently in the process of re-designing the Cub to be completely built out of carbon/foam sandwich. I am planning on using carbon infused flat panel that is all cnc cut and then laminated back together in a jig with the associated bulkhead structure. The wing has moulded ribs with a combination infused panels for spar, upper and lower skins as well as a eps hot wire cut nose section. Any further feed back on this topic would be appreciated. I have a business composite construction and this project from a construction method seems very straight fwds to me!!! Wielding lots of small pieces of tube together is not my skill and not up my alley

Dave Biggar sounds interesting, I was thinking of doing the same. Do you have any photos of your current build?