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Old Apr 08, 2003, 11:11 PM
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DerekB's Avatar
Cape Coral, FL
Joined Nov 2001
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Trident 3D, Fanfold design for GWS 300C

Here are a few pictures of my Trident 3D made from Bluecore fanfold foam. I will say right up front that it is an impersonation of George Hicks' Tribute. I chose the name 'Trident' because it is sort of similar to 'Tribute'. After seeing the video of the Tribute flying, I was very impressed. I hope George does very well with his kit. From what I have read, he put a huge amount of research into the design.

My version is not a design at all, but just a TLAR (That Looks About Right). So out of respect for George's work, I do not intend to make my plans available. I made some sketches, then drew the plans in AutoCAD. I scaled them to make 3 versions for various motor/battery combos: a 36" wingspan, 30" span and 24" span. My intention is to stay with the GWS EPS 300C, IPS dual and IPS single, respectively. My first try is the 36" span, shown in the photos:

Wingspan: 36"
Fuselage length: 36" nose to tip of rudder
Motor: GWS EPS 300C w/ D gear, retimed.
Prop: GWS 12x6
Battery: 8X720 NiMh (will get some 2s2p Kokam, or E-Tec's)
Servos: 3 GWS Pico
ESC: Jeti 05 (I think this is OK?, if not, I have a 10 A ESC)
AUW: 11.2 oz
Wing area: 2.53 sq ft (including ailerons)
Loading: 4.42 oz/sf (This includes ailerons, is that OK?)

I'm really excited about how it is turning out. After getting the body parts all assembled and just moving it around in the air by hand, it has a good feel to it. The balance is really nice too. The battery is only slightly forward of the main spar to get good CG. LiPo's will have to be farther forward, of course, but plenty of room. At 11.2 oz AUW and 13 + oz of thrust, this should fly pretty well for a fanfold foamie.

Derek

(update June 17, 2003: I finally posted my Trident plans in .dxf format for anyone to download. And just so you don't have to sort through all the posts, I will keep updating right here as to which page you can find them on. You can find the Trident plans on the 5th post down on page 28. Just to let you know, the picture in the first post on page 28 is a variation of the Trident, built by someone who is experimenting with different reinforcing techniques for the foam. As always, I appreciate everyone's ideas. You will find that by leaving the skin on the foam and reinforcing it per the plans, you will have great results. You are welcome to experiment any way you please.

There is also a preliminary plan for a Fun X 3D (based on the Funtana) that you can download on page 26, last post. I may change the name to Foamtana, if I get the OK from the person who thought of it. I'll start a new thread for construction of that, so look for that too. Have fun, Derek)
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Old Apr 08, 2003, 11:13 PM
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Cape Coral, FL
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Plans I drew in CAD

This is the 24" version. I'm trying the 36" version first.
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Old Apr 08, 2003, 11:16 PM
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Cape Coral, FL
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Fuselage parts

I used a short CF tube at the front of the fuselage and a 1/4" x .007 CF strip down the rest of the fuselage. This shows the parts laid out before glueing. The 1/4" CF strip is just held up with pins for the photo.
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Old Apr 08, 2003, 11:17 PM
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CF strip

The CF strip from ACP. Used to stiffen the fuselage and wing.
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Old Apr 08, 2003, 11:19 PM
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Wing ready for CF strip

The wing is cut in two down the approximate CG / spar location. The CF strip is just pinned in place for the photo.
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Old Apr 08, 2003, 11:21 PM
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Fuse and wing with CF glued in

I used 15 minute epoxy (sparingly) to glue in the CF strips and CF tube at the front. I ran out of foam safe CA and could not wait for a trip to the LHS tomorrow.

I think the resulting stiffness of the fuselage is adequate and the motor mount CF tube is "bomb". But the wing is a little too flexy. Maybe one more strip of CF. Or other people have used a CF tube in the wing, which is probably what it needs, but I didn't have one. I'll have to settle for a few strips of strapping tape for this go round. Flight tests will tell.
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Old Apr 08, 2003, 11:27 PM
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Cape Coral, FL
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Closeup of motor mount

I put a balsa plug in the gearbox and drilled it out to fit the CF tube. I actually used a short piece of CF tube in my drill and filed a sharp edge on the end and used that to "drill" the hole instead of a drill bit. The front end is pretty stiff. It might be a good idea to embed a short piece of flat CF strip low on the nose to help on bad landings. I'm going to add landing gear, but I need to get some 1/8" dia. CF tube for that.
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Old Apr 08, 2003, 11:28 PM
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Cape Coral, FL
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Tail feathers

That's a whole lot of movement back there......
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Old Apr 08, 2003, 11:29 PM
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Plan view

One final shot. I hope I did not over do it with the photos. I should have some test flights by this weekend.

Enjoy,
Derek
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Old Apr 09, 2003, 12:42 AM
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Pearl River, LA, USA
Joined Sep 2001
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Re: Plan view

Quote:
Originally posted by DerekB
One final shot. I hope I did not over do it with the photos.

Derek
Over do it?????!!!!!!! Come on we LOVE photos! The more the better!

Nice work! Ive got some Zepron, Im thinking of trying somthing like this and using the motor and GB form My Slow Stick.

Barrett
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Old Apr 17, 2003, 01:19 AM
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Singapore Holland Rd
Joined Mar 2002
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I think itll fly well nice plane good job I think use some lithium cells (2 cell packs) On the IPS dual 4.8v Like extreme team is using n WHA LA Flying as good as the real tribute
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Old Apr 17, 2003, 11:08 PM
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Cape Coral, FL
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Wing stiffener

I have been delayed to get this plane in the air. Meanwhile, I have been thinking of ways to stiffen the wing and I think I found something that works very well.

First, as I showed in previous photos, I embedded a .007x.25 CF strip as a "spar" down the CG of the wing. This did not add as much stiffness as I hoped. I even added a second strip near the leading edge (you can see in photo). This did not do much either. So I gave up on this method.

Then I thought of adding a strip flatwise to the top and bottom (15 minute epoxy). This GREATLY increased the stiffness. In fact, it is very stiff. This wing will not flex in flight under the loading of this airplane. To add the top strip, I flexed the wing upward about 1/4" and let the epoxy cure FULLY (unless cured fully, the epoxy will creap. If you can press your fingernail into it, then it's not cured yet). Then I turned the wing over and flexed it a little beyond flat and added the bottom strip and let that epoxy cure fully before releasing it.

I know that Radical RC has the CF strip top & bottom on their Edge 540 (which I have) and it greatly increased the stiffness. However, that is a thick wing, so the mechanics of how the strips work is totally different than on a thin wing.

What makes it work on a thin wing is the CF strip embedded in the middle that acts like the web of an I-beam. I tell you, this really works! I'm a structural engineer (you might laugh and say how come I never thought of this in the first place, but I never think of applying real world analysis to these little foamie airplanes).

The first photo shows the flat strip added to the top (and matching one on bottom). You can see the embedded piece continues to the wingtip. I only added the flat strip on 2/3's span - that seemed good enough.

Second photo is an exploded view of the resulting parts. You can see how the CF strips make an I-beam. This is the most efficient shape for stiffness and light weight. To make this photo, I just CA'd some short strips together. This might be the best way to start with a full length 36" piece, because you can use regular CA to make the joints. Then epoxy the wing pieces into the I-beam.

The CF strips are only .007 thick, so they are very light.

Derek
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Old Apr 17, 2003, 11:17 PM
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Cape Coral, FL
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I-Beam

There are 2 ways to create this I-beam. The first way is what I stumbled on. Epoxy the "web" piece between the split wing, then epoxy the "flanges" onto the top and bottom of the wing. The second way is to make the I-beam first, then apply epoxy and push the split wing pieces in. However, it might be difficult to hold the three 36" long pieces in place and square and straight while you CA them together. I think the 2nd method will ultimately work better because you can better control the amount of epoxy used to join the foam and thus save weight.

It was difficult to get a good photo, since the CF strips are so "black". Hopefully you can see the I-beam shape.

Derek
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Last edited by DerekB; Apr 17, 2003 at 11:38 PM.
Old Apr 18, 2003, 06:22 AM
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Singapore Holland Rd
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Is blue foam that light or is study board lighter?
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Old Apr 18, 2003, 03:16 PM
Foam rules
Thatovalguy's Avatar
HdG Md.
Joined Jan 2003
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I've been using sturdyboard and am now switching to fanfold. My sturdyBoard is double the weight of fanfold and is stronger but not by that much. Fanfold at 1/4" thick is .76oz a sq.ft. and 1/8" sturdyboard is .72oz a sq.ft., this is the way I've been using it and you need to add something to stiffen it up so by the time your done you don't save any weight at all.

Go fanfold, its your best bet.
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