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EPS 1000mm Scratch Built Wing

colorex

Rotor Riot!
Mentor
#1



Unnamed wing design.


So I want to try and build stuff out of EPS - you know, that crappy foam that falls into pieces if you touch it. I fiddled up a quick design, here are the dimensions and specs:

http://fwcg.3dzone.dk/?wing_span=10...ep_type=0&sweep=20&cg_pos=20&show_mac_lines=0

So it has 15 sq dm (232.5 sq in). I expect the foam to weigh 100 - 200 grams (3.5 - 7 ounces). The electronics should weigh in at 150 grams or 5.3 ounces (Slope Soarer - 2 Servos, Rx, Battery), which would give these wing loading calculations:

100 + 150 = 250 grams / 15 sq dm = 17 gr/sq dm (5.5 oz/sq ft)
200 + 150 = 350 grams / 15 sq dm = 23 gr/sq dm (7.4 oz/sq ft)

Cubic wing loading is 4.3 - 6 oz/cu ft which tells me it'll be really light, maybe even too light for slope soaring.

I might cover it with clear packing tape to protect it and make it stronger, but the tape doesn't stick well on EPS. Tape will make it heavier though.

If all fails I'll put a Park450 with an 8x4 and a 1300mAh 3S on it and it will go vertical for ever :D

What do you guys think?
 

lobstermash

Propaganda machine
Mentor
#2
Packing tape doesn't stick well to EPS, but it sticks well to itself. If the tape stays tight and loops on itself, and if there's enough reinforcement in the wing itself, it should be tough enough.
 

colorex

Rotor Riot!
Mentor
#3
Packing tape doesn't stick well to EPS, but it sticks well to itself. If the tape stays tight and loops on itself, and if there's enough reinforcement in the wing itself, it should be tough enough.
That's right teach. I'll wind the tape in line with the airflow to achieve this best.

BTW, control surfaces are also EPS, 35 cm in from the wingtips and 5 cm wide. I want good control at slow speed.
 

SteveOBHave

Senior Member
#4
Should be sweet :D Go for it! The only hiccough that I can see is possibly keeping the wing from flexing too much... What were your thoughts on spars etc?
 

earthsciteach

Moderator
Moderator
#5
Looks good. The motor choice sounds good, too. It will have plenty of power! SteveO is right about spars - definitely need something to reinforce it. Don't worry about the weight from the tape. THat motor will push it around just fine.
 

jetpackninja

More combat please...
Mentor
#6
Wingspan = 100 Is that cm? If so that will probably work well with a 450 motor. What KV?
I prefer more sweep. It makes the wing a little less sensitive to cg. Try plugging 30 into the sweep field and see how that looks to you.
What kind of airfoil are you using?
Are you hotwire cutting the airfoil?
Or doing a KF airfoil?
To get the most out of the tape's ability to keep the wing from flexing, you may consider taping to line up with the LE and TE of the wing.
Checkout the taping pattern that my friend Adrian uses for his ExtremeWing:
http://www.extremewing.com/wing/?page_id=27
 

earthsciteach

Moderator
Moderator
#8
I doubt Andre has that in Ecuador. Its warm/hot year round and I doubt there are building energy codes like we have here in the states. But, even though it is brittle, the "cooler" foam, reinforced properly and not flown like our combat wings, is probably a legit material.
 

SteveOBHave

Senior Member
#9
Andre, I was wondering if you've thought about trying your hand at making a hotwire? Even the nastiest EPS will come out with a nice finish if you can use a hotwire.
 

jetpackninja

More combat please...
Mentor
#10
I fly everything like a combat wing ;)
If you've ever seen pics of my slow sticks and my supercub...
I doubt Andre has that in Ecuador. Its warm/hot year round and I doubt there are building energy codes like we have here in the states. But, even though it is brittle, the "cooler" foam, reinforced properly and not flown like our combat wings, is probably a legit material.
 

earthsciteach

Moderator
Moderator
#11
LOL! Yeah - me, too! That's why my Super Cub is upside down on my kitchen table beside me at this very moment, my F6F Hellcat has a wing broken in 3 places and a broken prop shaft. Its just more fun that way!
 

jetpackninja

More combat please...
Mentor
#12
Yes- My supercub is waiting for me to get over crashing long enough to where I feel like fixing it. I'm torn between building a new one from "scratch" (new parts from HZ) or just getting a new wing and cutting ailerons in. I've got servos as long as I don't use them in other projects ;)

Other projects:
Two GWS corsairs crashed and donated to Team Jetpackninja
One GWS corsair kit, may be a winter build project, we'll see
One GWS Spitfire that is flying condition
My new updated PZ Corsair, hope to maiden this weekend if the retracts do happen to show up.
I've got a CTH two Scythe pack just waiting to be built, Oh Yeah and a Reaper too (night plane project? -mmmmaybe)
5 piece of $Tree foam that keep talking to me everytime I walk into the shop, must listen closely to see what they want to become...
Oh yeah- and a couple 'o combat wing repairs ;)

Did I ever mention that I have ADD?
 
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earthsciteach

Moderator
Moderator
#13
What were we talking about???

Yeah, that ADD thing.... I started a 55mm edf scratch build Sunday night and have already grown bored with it. Oh, then there's my Red Tailed Hawk that simply needs to be thrown into the air. Maybe someday. Oh, that fpv fiberglass wing - its still on the front burner, but every time I think I can pull the trigger on an investment in epoxy resin either a car repair or some bizarre bank anomaly gets in the way. This week's anomaly - call from our debit card issuer. Our card has been compromised. As such, it is no longer valid. Have to wait 1 to 2 weeks for a new card.

On a progressive note, I have revisited my scratch built biplane. It is ready to take to the skies. Problem is, my 1000mah, 2 cell Blue LiPo beeps error on my charger. I HATE NITROPLANE BLUE LIPOS!!!! Nothing but problems! Maybe I'll use my HK 2200 2 cell.

At least my wing and my new Wing Surfer/Sky Surfer/Bixler and my Assassin are as reliable as the sun coming up tomorrow!
 

jetpackninja

More combat please...
Mentor
#14
I HATE NITROPLANE BLUE LIPOS!!!!
Really? I know people that swear by them.
I did like the GensAce batts but every one of them that I have purchased has lost it's punch and need retired.
Yes, I'm hard on my batteries, not fair what I put them through.
I don't buy anything but nanotechs now and since I've standardized on the xt60 connector it just makes life easier.

What kind of charger do you have? Invest in an Accucel-6. if you get a low cell you can often bring them back by charging in nimhi or pb batt mode enough to bring them high enough that the lipo charger no longer errors- they may or may not be as good as they were before, but usually usable.

To keep on post. Andre what's up?We are waiting to see some pictures :)
 

earthsciteach

Moderator
Moderator
#15
I have a Supermate DC-6 charger. I can and have recovered LiPos with it. The issue with Blue LiPos is that, they either arrive DOA or the balancing leads pull out and have to be soldered back in. I think that is the issue with this particular one.

I had a couple of "Pete Signature Series" Genesis batteries. I was very impressed with them. But, I lost one (as in left it somewhere), and used the other up until my last crash with the Super Cub. Aside from those, I am a Nanotech fan, too. Good, solid batteries for a good price.

What IS Andre up to? Last I saw, he was apparently eating pizza...
 

colorex

Rotor Riot!
Mentor
#16
Sorry guys, I had totally forgotten about this thread... and missed it when I was away.

Should be sweet :D Go for it! The only hiccough that I can see is possibly keeping the wing from flexing too much... What were your thoughts on spars etc?
I might put a 3/16" (5mm) round wooden dowel in the wing to reinforce it. Curved like when Josh Bixler put fiberglass in the speedwing.

Looks good. The motor choice sounds good, too. It will have plenty of power! SteveO is right about spars - definitely need something to reinforce it. Don't worry about the weight from the tape. THat motor will push it around just fine.
The motor will be OK - but it won't be fast. The Kv on it is 1000, so the max speed would be around 40 mph. But it will go vertical :D

Wingspan = 100 Is that cm? If so that will probably work well with a 450 motor. What KV?
I prefer more sweep. It makes the wing a little less sensitive to cg. Try plugging 30 into the sweep field and see how that looks to you.
What kind of airfoil are you using?
Are you hotwire cutting the airfoil?
Or doing a KF airfoil?
To get the most out of the tape's ability to keep the wing from flexing, you may consider taping to line up with the LE and TE of the wing.
Checkout the taping pattern that my friend Adrian uses for his ExtremeWing:
http://www.extremewing.com/wing/?page_id=27
Yes, 100 is cm. I decided to change the design a bit, and add some more area.

http://fwcg.3dzone.dk/?wing_span=10...ep_type=0&sweep=30&cg_pos=20&show_mac_lines=0



I am planning to do a KFm2 airfoil - with each layer of 2 cm, or 3/4". Total thickness 1 1/2".

Thanks for the link, I'll follow that guide if the foam allows me to do it.

Surely you can find blue core or pink foam insulation?
I cannot.

I doubt Andre has that in Ecuador. Its warm/hot year round and I doubt there are building energy codes like we have here in the states. But, even though it is brittle, the "cooler" foam, reinforced properly and not flown like our combat wings, is probably a legit material.
Teach is right :D it's always hot here, so no need for insulation.

Andre, I was wondering if you've thought about trying your hand at making a hotwire? Even the nastiest EPS will come out with a nice finish if you can use a hotwire.
I have not, as I have not come upon a free computer power unit. And my poor e-guitar is stringless.

To keep on post. Andre what's up?We are waiting to see some pictures :)
Eventually there will be pictures! But of what, I do not know, for my Park450 has been changing it's planned location a lot :D

First a tricopter thrust booster, then a profile 3D biplane, then a single wing profile 3D, then a balsa Extra 300S, then a swamp boat, and now a flying wing... We'll see...

What IS Andre up to? Last I saw, he was apparently eating pizza...
The pizza was really good! :D
 

colorex

Rotor Riot!
Mentor
#17
Pictures!

Here is a small construction paper prototype I just made. It's 8" wingspan, 1/5th scale.



I used a small 4GB flash drive taped in place to get the CG right, CG is 1 3/8" from nose (3.5 cm). Calculated using the online tool.

http://fwcg.3dzone.dk/?wing_span=20...eep_type=0&sweep=6&cg_pos=15&show_mac_lines=0

I glided it across the room - and dropped my jaw! It tracked completely straight 15' across the room until it hit the wall!

I'll be making lot's more of these cute thingies, and I'll make an article about them too :D
 
#19
I'm pretty sure that you can use a Lipo charger as your hotwire power supply and that's especially good since you can modulate the output on it.