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  1. #1

    EPP, Coroplast, Carbon fiber 2M thermal ship

    I am about mid-way to getting this baby done...

    It's a high performance EPP wing and nose pod, CF boom and Coroplast tail feathers.

    OBJECTIVE: A durable high performance thermal (and some what all around) ship that I am not afraid to launch in the sketchiest of conditions or worst of flying sites. I want something that I can bang around, yet still have a good performance envelope. Also discus launching is in the back of my mind...

    You can check out photos and my progress here:

    http://hobiehawk.com/EppHyper.html

    Cheers,

    CactusJackSlade
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  2. #2

    Getting closer!

    Here is a photo of the main parts assembled...

    For all the detail photos go here:

    http://hobiehawk.com/EppHyper.html

    Cheers,

    CJS
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  3. #3

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    Looking good

    Cactus Jack,

    My SW 1-26 is very versatile -- probably the most versatile plane in my slope fleet. I noticed you took great pains to save weight. That's a relatively thick wing, and it can carry a wide range of weight. It looks like you're really optimizing everything else for "no lift" conditions.

    Looks like a fun project. Let us know how it flys, and stands up to the rigors of discus.

    Joe
    Arguing with an engineer is like wrestling a pig. Everyone gets dirty and the pig likes it.

  4. #4
    SciFiFlyer's Avatar
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    Some wing suggestions...

    The wings from Dave will work fine for an all-around glider. If you want to go thinner on the airfoil you can use 1.9lb EPP, which is used in a few slope racers with 10% airfoils. Also, I noticed you are using wood spars instead of carbon arrow shafts (cheap shafts at Walmart after hunting season!). Get a postal electronic scale and weigh the wood versus carbon, you may save a lot of weight by switching. Only downside is the carbon will bend a lot when winched. If you use a heavy spray of 3M 77 in the spar slots instead of Goop, that will also save a few grams (Goop good for combat, bad for thermals). Just weigh down the wing warp-free and set your spars in quickly as the spray sets up fast. What's your boom made of? I'll bet you could secure 4"x1/8" carbon rods into the boom that you could slide and tape the ruddervators onto for a stiffer tail that is also removable. Try using WeldWood brush-on contact cement (for covering prep) on an EPP scrap; if the results are good, use weldwood sparingly on the leading edges to avoid heat-related sagging of the covering and 77 everywhere else. This will give you a cleaner airfoil up front without a lot of weight, wrinkles are inevitable with 77. Clean up the LE of the coroplast with light balsa, sanded and taped over the front if you wish.

  5. #5

    Epp plane

    SciFiFlyer Yeah,

    On my next project like this I'm going to use a 2 pc wing design and hollow carbon spars with a (thin) horizontal plate (for stiffness). I'm going to use the hollow spars as the mounting means onto the fuse with a joiner rod.

    I was wondering about the covering... I have used orocover on my last foamie and did not like the results - it saged. I figured it was because it did not stick properly to the foam around the edges and when I shrunk the covering it probably pulled a bit away from the edges causing sags.

    On this proto I was just going to do the ol' 3M 77 and packing tape thing since I am going to be testing various wing tip designs... so I'll be cutting the wingtips off after I test it the way it is...

    For the boom I'm using a CF tube .050 OD with a .040 wall thickness. It's about twice as thick (and heavy!) as I'd like, but I can not find anything better that is long enough (at a reasonable price.

    To compare, the Art Hobby tapered booms are about .0135 thick and weigh 11 grams for a boom 26" long and the one I'm using for my proto weigh 56 grams! So I'm NOT happy with my boom choice right now.

    I would really like to find a wrapped CF tube .50" OD with a .020 wall thickness - that would be a good compromise between weight and strength for this type of craft.

    On the Coroplast, I already cut and tapered all the edges, and yes I used carbon rod into a tail mounting block and just slid the coroplast onto it - works well, should be fairly durable.

    Any other suggestions? I've learned a lot already, my next one should be a lot better!

    I am installing radio eqt right now, should be flying in a day or two...

    I will post more pic's as I have time, here's what I have so far:

    http://hobiehawk.com/EppHyper.html

    Here is a pic of the completed V tail assembly - it slides onto the CF boom and is retained by one small screw - I wanted everything removable, again, not the lightest set-up...


    CJS
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  6. #6

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    awesome!

    Thats a great set of pictures. I've wanted to do a scratch built plane now for a while, and I think I might follow your buildup.

    The wings are the right price, the boom isn't bad, I have all the carbon and glass I might need. Let me ask how did you taper the coroplast, and how did you get the covering to stick to it?

    Would bagging the wings with a light glass or carbon cloth be possible? I'm not sure how much vaccumm that foam will take.

    It looks great btw!

  7. #7

    Tapered Coroplast

    TheoA:

    TheoA Q: The wings are the right price, the boom isn't bad, I have all the carbon and glass I might need. Let me ask how did you taper the coroplast, and how did you get the covering to stick to it?


    A: To tper the coroplast I use my dremel tool with a small cutting wheel on it - I like it to go deep enough to completely cut out 1 or 2 "ribs" from the coroplast. I then just pinch it together and use scotch tape or packing tape to hold the edges together. If you taper a length of 2 sections it makes a nice trailing edge.

    The covering is actually just colored packing tape like you would use on your Zagi or the like...

    TheoA Q: Would bagging the wings with a light glass or carbon cloth be possible? I'm not sure how much vaccumm that foam will take.

    A: Well, I have not done any bagging yet of any kind so I can't answer that... I do know that with constant pressure EPP will squish down a LOT!... so I am a bit dubious that it would work at all. Probably end up with a FLAT wing! :-o

    I am covering the wing now, radio is installed, look for more photos and flight info soon!

    CJS
    http://www.hobiehawk.com
    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  8. #8

    Tapered Coroplast

    TheoA:

    TheoA Q: The wings are the right price, the boom isn't bad, I have all the carbon and glass I might need. Let me ask how did you taper the coroplast, and how did you get the covering to stick to it?


    A: To tper the coroplast I use my dremel tool with a small cutting wheel on it - I like it to go deep enough to completely cut out 1 or 2 "ribs" from the coroplast. I then just pinch it together and use scotch tape or packing tape to hold the edges together. If you taper a length of 2 sections it makes a nice trailing edge.

    The covering is actually just colored packing tape like you would use on your Zagi or the like...

    TheoA Q: Would bagging the wings with a light glass or carbon cloth be possible? I'm not sure how much vaccumm that foam will take.

    A: Well, I have not done any bagging yet of any kind so I can't answer that... I do know that with constant pressure EPP will squish down a LOT!... so I am a bit dubious that it would work at all. Probably end up with a FLAT wing! :-o

    I am covering the wing now, radio is installed, look for more photos and flight info soon!

    CJS
    http://www.hobiehawk.com
    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  9. #9

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    Bagging EPP ?

    Originally posted by outbound
    TheoA:



    TheoA Q: Would bagging the wings with a light glass or carbon cloth be possible? I'm not sure how much vaccumm that foam will take.

    A: Well, I have not done any bagging yet of any kind so I can't answer that... I do know that with constant pressure EPP will squish down a LOT!... so I am a bit dubious that it would work at all. Probably end up with a FLAT wing! :-o

    CJS
    http://www.hobiehawk.com
    Guys,

    Are you still talking about EPP wings? Would you also be considering using epoxy for the glue during bagging?

    The original plane I saw in Outbound's post was a light slope plane using a DAW 1-26 EPP wing. I'm not sure why you'd want to start putting "crunchy" materials on a squishy foam core.

    Bass is a great spar for absorbing impact. You can use carbon if you have generous "crumple zones" with a flexible skin around it (ie, Comanche, Aurora, Sonic, JW and other Bowman designs).

    I'm having trouble envisioning any sort of "bagged" skin on EPP, with materials that need a stiff glue matrix to really add benefit (ie, glass and carbon). I thought about using Elmers "pro Bond" polyurethane glue over EPP a while back, but talked myself out of the idea. My whole premise is that if you're talking EPP, you're in the realm of foamies, and want a plane that can get dinged and still fly the same before the contact occurred.

    Unless I'm way behind the technology curve, the bagged surfaces I know about get crunched on impact, and stay that way.

    Did I miss something?
    Arguing with an engineer is like wrestling a pig. Everyone gets dirty and the pig likes it.

  10. #10

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    oops

    I neglected to mention that I'd be using pink foam on my wings. I suppose at 115am after a long day of driving, my brain isn't working quite the way I expect it. duh award goes to me

  11. #11

    Bagged EPP wings

    Wind Junkie:

    On the bagged epp wing thing, I was just answering TheoA's question... you are correct - I would not put any crunchie material on this plane - it would defeat my original goal: High performance FOAMIE.

    I have gone to pains to make sure I have impact resistance in mind... also as it turns out the whole tail/pod/boom arrangement is replaceable piece by piece. It's a little heavier this way, but EZ to repair/replace stuff at the field.

    I just finished re-doing the wing tips with a little "washout" and a more "modern" tip... but the trailing edge is a bit FAT and may give me a parisitic drag penalty... well, that's what I get for using EPP the way I am... still over all I think my goals are being met...

    I also finished covering the wing, just need to cover pod and it's ready to fly!
    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  12. #12

    Wing done!

    OK,

    Here is the finished wing.

    The mods from the stock DAW wing kit include:

    Different "more modern" wing tips
    Kevlar "cable" from tip to tip on the spar
    Glassed joiner area for mounting dowel and screw hole

    Next time I will make this a 2 pc wing - that would be a sweet transport set-up...

    Here are a few photos...
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  13. #13

    Wing done...

    Another photo
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  14. #14

    Underside of wing

    The belly side...
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  15. #15

    Belly 2...

    Belly number two...

    Hey, is there a way to post more than one photo at a time?
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  16. #16
    lvspark's Avatar
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    EPP, Coroplast, Carbon fiber 2M thermal ship

    Thats looking really nice, hope the first lights go well.

  17. #17

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    2m superfoamie

    CactusJack: that 2m high-performance foamie is a GREAT project!

    I fly in Denver from some slopes that are great for flying and bad for landing. On DL-ing a 2M foamie: I built a high-performance wet-bagged pink foam DLG with a 68" span for flying these slopes under a wide range of lift conditions. It weighs 28oz, flies superbly, but is my personal limit for launching, in both span and weight. I am 5'9'' and weigh 175 lbs and am pretty fit. If you're taller and stronger you might be able to DL a 2m, but the vee tail WON"T WORK!! There is just too much torsion on the tailboom and mounting, unless you build it hell-for-stout and heavy.

    I've been flying a 2m Boar on these slopes, sometimes with a 10-oz lead sheet shaped and taped around the bottom of the fuse pod. I glued the balsa vee tail to the bottom of the boom: much more mounting surface than on top. The balsa is glassed over the middle, covered with Monokote, and has .040 CF rods glassed onto the LE. The Boar and I have made some pretty horrible non-landings, breaking the fuse 3 times. The stab is still undamaged, so maybe there isn't any need for the flex, the weight, and the crude shape of a coroplast tail.

    Tailbooms: the ArtHobby boom on the Boar has never broken, even though it once broke the fuselage right across the joint.

    Thanks for sharing the project!

    Ed
    Ed

  18. #18
    SciFiFlyer's Avatar
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    Looking good!

    Great progress!

    Look at the booms at www.tailboom.com ,even though they're all tapered and meant for application with Dr. Drela's designs. Or luck upon a broken graphite fishing rod like I did, not too heavy and very stiff.

    I put together a set of 60" hlg wings from Dave built with carbon arrow shaft spars and ailerons, something my young nephew can get airborne with. I'll try it out this year at the earliest opportunity.

    Take care with surface preparation before covering, sand and vacuum everything including the tape! Tape has a release agent on the back so it won't stick to itself on the roll, and it also keeps covering from sticking!! Knock off the shine with 220 grit before spraying 77.

    Cheap-ass Towerkote from Tower Hobbies has been the least wrinklely covering I've used on my 4 foamies. Very low heat, start at 1/3 power on your iron. Stcks good and goes over complex curves easily.

  19. #19

    Project COMPLETE!

    Well,

    Here it is!

    I test tossed it this late afternoon and in ZERO wind and fading light. Only minor trim changes during the flight - this baby FLOATS!

    For a 33 oz foamie I was very pleased! I was tossing from a small "bump" at the end of two soccer fields - maybe about 8 feet above the field and it went accros the one field and 1/4 the way across the other - very nice!

    I tossed it back and forth a few times then stood on the "bump" and did 360 degree throw and catches until it was dark! Turns well, doesn't fall out or into the turn, well tempered!

    I will set up my bungie launch tomorrow! It seems to handle very well, but given the conditions I was trying to "float it" so I will need to really put it through its paces before I make the final call but so far I am STOKED!

    Here is a photo of the finished project:
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    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  20. #20

    Discus launching

    SoarEd:

    Whadda ya mean I can't discus launch a vee tail??? I do it with my Colibri all the time - of course it ends up up-side down and sideways! Just gotta be quick on the controls! ;-) ....

    Actually I made the whole tail feathers section removable with the intent of using a "+" like configuration tail like on my Taboo DLG.

    Yes, I think there are a few companies that advertise their V tail planes as discus launchable, but I think you have to be pretty skilled to pull that off! I really have tried many times with my V tail Colibri 1M and it basically flutters around and ends up in wierd positions... and always upside down!

    Oh, if you can see the dark patch in the left forewing tip area, that some CF plating I sandwiched onto the spar for a throwing peg.

    Oh, one other thing - the DAW wing I used they call a "2 meter" but it is only 71" not the typical 78-79" you would normally find on a "2 meter"... so this is really a 1.8 meter!... I've been meaning to contact them about that. For this project I don't really care, but I don't think they should call a 71" wing a "2 meter" ya know?

    Anyway, I hope to fly this tomorrow for real on a bungie launch or large hill if wind permits...

    I'll keep you all posted!
    CactusJackSlade

    http://www.hobiehawk.com (Foamie stuff too!)

  21. #21

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    Congratulations!

    CactusJack: Way to go! The kick you get out of seeing your latest creation go off and fly is why I design and scratch-build my ships. You just can't replace that feeling of accomplishment any other way! What's the section on that 1.8m wing? It must have pretty good camber...maybe a Seelig 7037? But it sounds like it has good L/D, too.

    Where do you fly? If you're in the Denver region, we oughta hook up to compare foamie building ideas. I've done up a couple of EPP fuselages to use with wings left over from foamie kits. Depending on the wing section, they make good beginners' ships or beginning DS ships. And I'm always looking for new slopes to try. Being able to base-fly slopes with a 90 foot discus launch opens up SO MUCH COUNTRYSIDE!
    Ed


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