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Old Aug 12, 2003, 06:14 AM
Don Sims is offline
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3D Fan Fold Ultimate Bipe and 3DX....V3 Started by TimH.


Here's the link to V-2:
https://www.rcgroups.com/forums/show...5&pagenumber=1

And for those interested: https://www.rcgroups.com/forums/show...15&pagenumber=1

Is the link to this 3D Extravaganza of a thread started by Tim H..
Don
Last edited by Don Sims; Aug 12, 2003 at 06:19 AM.
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Old Aug 14, 2003, 02:02 AM
jnyoun is offline
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Hi

I built my first fan-fold profile Gee-Bee and was impressed how it flies. It flies great and hovers at about 3/4 throttle. At full throttle, it goes vertical. Only complaint I have is the flight time is too short. I would say 4 mins. After 4 mins, the plane starts to have a lot of dragging. Here is my set-up for your reference:

Motor GWS 350C with D-Gear
GWS 12x6 Prop
Li-Poly 2S2P (so, 2200ma, each one has a capacity of 1100ma)
AUW 12.7oz including batter pack.

After reading this UB airplane, I am going to build one. I am hoping to able to get a brushless motor this time. However, my big concern is 'WILL THE BRUSHLESS MOTOR INCREASE THE FLIGHT TIME ? IF SO, HOW MUCH compared to 4 mins'. This time is about 3/4 thottle all the time. Also, I read the messages about what's a good motor for UB. However, there are too many choices. May be razer 350 or BL20. I am not sure which one for me.

I really appreciate your help in advance.

Thanks.

JN
Old Aug 14, 2003, 02:05 AM
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Oh, by the way, how do I post a picture ? I will be happy to show some pictures of my Gee Bee.
Old Aug 14, 2003, 08:17 PM
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Seriously bummed guys. I just got back from flying my 3DX for the 6th and a half time. About half way through the pack and at the bottom of a not especially tight or fast loop, the wing decided to fold up on me! Fortunately, I was pretty low, so no damage to the motor or electronics from the resulting impact as far as I can tell. The CF tape on the top of the wing actually snapped in compression. Not sure what the cause was, but the I-beam wasn't exactly perfect due to the waviness of FFF. I may have to rebuild with Depron, but do I want to wait that long???? I mean I have at leats 20 sheets of FFF in the other room just waiting to fly. God this is a tough choice!

BTW, thanks Tim for a fun and simple design
Old Aug 14, 2003, 09:14 PM
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Hey guys, new video is up http://www.foamyfactory.com/videos.htm Mike Hammel's (mycammel) Edge540 with a razor 350.

JN - A brushless will increase flight time due to better efficiency. The 2s2p pack may not be enough voltage though. However, you should be getting MUCH longer flight times. To post a picture, post a reply as usual, when you are done writing, scroll down to where it says "attach file". Browse your hard drive for the proper pic file, and click on "open". Then when you submit the post, the pic will be shown.

Member73 - Wow! Never heard of that happening... I guess the I beam failed at a weak spot. Depron is great, but FF is fun too.

Sorry I've been a stranger... Work is still taking all of my fun time away Keep up the great work and keep 'em flying!

Tim
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Old Aug 14, 2003, 10:46 PM
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Hi Tim, Any chance of getting the cab forward design and a 24 inch scaled down 3DX?

Thanks,
BC
Old Aug 14, 2003, 11:33 PM
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Tim, I'm just as surprised as you are. I thought that I-beam was going to be bullet proof. I blame the builder not the designer, that's for sure.
Old Aug 14, 2003, 11:42 PM
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UB35 with UB30 maiden tomorrow
Old Aug 14, 2003, 11:56 PM
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Hello Member73

I've built numerous carbon spars for open class RC sailplanes over the years. (And I'm flying Tim's 3DX & learning to hover - lots of FUN) It is very common to use MORE carbon on the top of a sailplane's spar than the bottom. The reason is that sailplanes generally see massive positive G's during the zoom portion of a winch launch ... and carbon fiber just doesn't handle compressive loads as well as tensile loads. So we use more CF on the top than bottom.

A couple of ideas for our simple I-beam spars:
1. Minimize the waviness in the F3 if you can. Maybe run a sanding block briefly over both sides. You don't want to dramatically thin the wing, but waves will create stress risers.
2. Ensure a GOOD bond to both the shear web & F3. If any part of the top of the I-beam is able to pull away from the foam - even a bit - it WILL. And then it will fail THERE. I'd think this is what happened to you.
3. Consider making the top/bottom of the I-beam wider, both for better management of compressive loads, and for better adhesion to the underlying foam and shear web.
Old Aug 15, 2003, 01:00 AM
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Right thrust?


Ok Guy`s I have looked a little bit but I cannot get Back to V1 of this thread to find out if i need any Right thrust to this. PLEASE Say you need 2 degreees right and 1 down...PLEASE.

Mal
Old Aug 15, 2003, 08:16 AM
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Mal - that's fine on the 3DX. On the Ultimate, 2 right and 2 up is good.

Looks great Joe! Good luck on the maiden...

Tim
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Old Aug 15, 2003, 09:47 AM
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Thanks Thomas-
I'm familiar with CF's lack of compressive strength, but that didn't stop me from sloppy building! I'll be more careful next time.
Old Aug 15, 2003, 11:01 AM
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hmmmmm Welll Hupefully things will be fine with the Down in her....Only one real way to find out isn`t there?

Mal
Old Aug 15, 2003, 12:52 PM
Tim H. is offline
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Quote:
Originally posted by bcripe1
Hi Tim, Any chance of getting the cab forward design and a 24 inch scaled down 3DX?

Thanks,
BC
BC - Hopefully next week will be a bit clamer at work than the last few. I can probably get to the scaling by tues or so. The Cab forward 3DX is a ways off yet. I have a few things I need to get done first (nice surprise maybe...)

Tim H.
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Old Aug 15, 2003, 01:40 PM
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I'm having a blast with my 30" Ultimate. Wondering if anybody has any ideas for a removable battery on the ultimate? Right now she's glued in and tie wrapped on the nose. It would be nice to have two batteries to swap between flights.


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