New GiantBipe Design from SlowBipe - Page 4 - RC Groups
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Nov 14, 2012, 10:11 AM
Proverbs 12:15
dougbo's Avatar
Sounds like there is some excitement for sure - be interesting to see if others jump on board. I'm thinking a few local fliers that are more "experienced" might like the slow easy flight and easy to see size.

Doug B.
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Nov 14, 2012, 10:13 AM
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SlowBipe's Avatar
Thank you everyone for the enthusiasm.

This thread will probably slow down a bit again. My sister in law (37 years old) was diagnosed with stage 3 cancer 4 weeks ago. She lives in London and must receive her treatment there. My wife has been away in London for the past 2 1/2 weeks helping her with her treatment. When my wife leaves town is usually when I get most of my design work done.

Last week my oldest daughter went into the hospital as well because of pregnancy related problems. I have also been spending a bunch of my time watching my two granddaughters as her husband works 2 jobs and goes to school. Her husband has been my full time employee, but now he is back to working somewhere else. I may bring him back on when I can get these new designs ironed out and ready for production.

I also work a regular full time job 5 days a week.

My goal will still be to get this plane flying before Christmas. I promise to not leave it stagnant for as long as the last time. I am very close as the only real hurdle is now the wing design.

I really will appreciate the local pickup from each of you who are willing to test one out and put it through the ringer. I am not looking forward to solving the packing issues. I believe that I will be able to pack up a kit in one Bicycle box, but am not sure at this point. If so, I expect about a $60 to $70 shipping cost to the east coast, with west coast shipping to be smaller. It may turn out that the plane never completely makes it to production, but that doesn't mean that a few planes can't be built.

Thanks again for all of the enthusiasm as well as the posts. It really is what keeps me motivated.

SlowBipe
Nov 14, 2012, 10:28 AM
Registered User
SlowBipe's Avatar
I want to talk about wing design for a minute. The original 80" GiantBipe top wing was made from 1/2 dow foam. The problem was that this material will not roll to the under camber without snapping. I solved this problem by cutting slots through the wing from tip to tip about every 1/2 inch. These slots were cut on a table saw and went about half way into the foam. I then had to add additional hardwood leading and trailing edges to keep the wing from bowing in the middle when the wing was rolled. It was still very difficult to get the foam to roll and say in that position. The wing struts and wing saddle kept these in place.

The lower wing was made from 1/4 fanfold and had leading and trailing hardwood glued and taped to the foam. This was a very light solution, but much too flexible for what I am trying to accomplish with this design.

I have done tests where I glue a 3mm depron sheet to the top of 1/2" white insulation foam. I then cut out the perimeter for the final wing. This seems to roll okay as the 3mm depron top sheet keeps the top from expanding when I roll and the white insulation foam has the capability of compressing on the bottom of the wing. Still this solution will require about 11 to 12 oz per wing panel and we have 4 of them. I really want a wing panel that doesn't need to be rolled and will just take the form of the struts and the wing saddle.

After the huge success of the honeycomb structure I used in the tail feathers, I am thinking of using some similar tech in the design of my wings. I really want my wing weight to be 7 oz per panel, which would keep my total plane weight down to about 8.5 lbs. This is with a 14 oz motor and two 11 oz 3 cell 4000 mah packs.

If anyone has any thoughts on this idea please post.

The only question I have is whether having a non smooth surface on the bottom of my wings will create a disruptive drag that would be undesirable. I tend to think it won't make much of a difference since my airspeed should never exceed 10 mph. I think I may do a test of this on my standard size SlowBipe. There is much less waste when something goes wrong.

SlowBipe
Nov 14, 2012, 10:31 AM
Registered User
Sorry to hear about your family situation. you will be in my prayer
Take care!
Nov 14, 2012, 10:37 AM
Registered User
I dont know much about plane design.
Would a flat wing works or would that totally change the design
and flying characteristic of the plane?
Nov 14, 2012, 12:11 PM
I Used To Have More Free Time!
SlowBipe,
I hope your sister in law and daughter get well soon. Family always comes first.
Whatever the shipping may be to NC, I am up for it.
Regarding the wing panels. I think the honeycomb idea is on the right track for the bottom of the two wings. The honey comb doesn't have to protrude all the way through the wing does it? So the top of the wings could be foam, and then why not cover the bottom of the wings with some transparent film to show off the honeycomb? This would solve the drag problem and look really cool. When I first saw the rudder all honeycombed out, I thought to myself that it really is a shame to cover that with depron. So why not cut the honeycomb out to half depth or something similar (whatever it takes to get the roll you are after) and leave the rest of the foam for rigidity purposes?
Nov 14, 2012, 12:30 PM
You're killin' me Smalls
BrownEyedFool's Avatar
Take care of your family. Foam can wait.

Do you have to have an undercambered wing? Can you get away with more of an Armin wing? Airfoil on top and flat bottomed? (I've been watching Flitetest Mini Blender videos lately). In that case you could do the wing bottom with flat honeycombed layer, mount a small number of ribs on it and put the top sheet on top. Using some sort of covering film on the bottom to close up the holes and eliminate the drag should be straightforward, you could even cover the whole wing to seal it all up.

Otherwise to get the curvature you want I'm imagining making forming jigs to stick in an oven like the guys have been doing forever with FFF, but you'd need a massive pizza oven to do this and it'd still be floppy.

Imagine the possibilities for mounting lights inside a wing made that way.
Nov 14, 2012, 12:47 PM
I Used To Have More Free Time!
IMO, the undercambered wings just go with the rest of the curves of the design.
I agree that lights in a design like you speak of would be cool.
If the honeycomb only went into the foam half way or so, one could paint each "cell" of the honeycomb to create a wicked looking pattern...
Nov 14, 2012, 01:56 PM
Registered User
SlowBipe's Avatar
Thank you all so much for the suggestions. I really do appreciate any comments as it makes me think outside the box.

I think one thing I am solid on is that the under camber design has to stay. It is integral to the performance and the structure of the plane. For strength if forms sort of a C channel which greatly enhances the strength of the wing for the minimum amount of weight. The under camber in the way it is implemented also gives the plane wickedly slow flight. It will stand still in a 2mph head wind. It also provides for an almost non existent stall.

The current thinking that I will test is to cut a honeycomb core similar to the rudder, but designed with solid areas where needed for the wing. Then I will laminate the core to a sheet of 3mm depron on one side. If I thin out the honeycomb webbing enough the wing should roll easily by compressing the bottom (honeycomb) portion. The depron on top will hold position.

I usually anticipate results of a build pretty well and feel confident that there can be a solution here that is better than others that I have done before.

Anyway you look at it, it's a very large wing. Total square feet is about 30. A 4 x 8 foot sheet of plywood is 32 sq feet.

I really thought the same thing when I cut out the honeycomb, that it's a shame to cover it up. For the rudder I considered adding some carbon rod to stiffen up the honeycomb and then just covering it up with iron on. However, even the light MonoKote ends up weighing about 1/2 as much as the 3mm depron skin. Plus in the end I don't think it would be as flat and stiff.

Please keep the great ideas coming.

SlowBipe
Nov 14, 2012, 07:21 PM
Registered User
Austin42's Avatar

why not just make ribs and spars form foam


you should just build a traditional wing skeleton with ribs and spars out of foam and skin it with the same foam you are skinning your honey combing with. Then there is no rolling needed it is built in.
Nov 15, 2012, 12:06 AM
Registered User
SlowBipe's Avatar
Quote:
Originally Posted by Austin42
you should just build a traditional wing skeleton with ribs and spars out of foam and skin it with the same foam you are skinning your honey combing with. Then there is no rolling needed it is built in.
Thanks Austin! Those are great ideas. As usual you will have to come over to the house and explain it more to me.

Have a great night.

SlowBipe
Nov 15, 2012, 08:11 PM
Registered User

Another wing idea


Would two layers of 1/4" FFF work?
Nov 15, 2012, 08:15 PM
Registered User
Quote:
Originally Posted by jb753
Would two layers of 1/4" FFF work?
Thats a great idea if you were building one. but I think that would make it hard to ship since the wing is not flat now. Instead of 1/2" thick, now the wing is about 4" of space in the box
Nov 16, 2012, 12:04 AM
Registered User
SlowBipe's Avatar
Quote:
Originally Posted by lv2soar
Thats a great idea if you were building one. but I think that would make it hard to ship since the wing is not flat now. Instead of 1/2" thick, now the wing is about 4" of space in the box
That is a great idea, and I agree if the two fanfold pieces were laminated together they would need to be rolled first. And yes, packing does have to be a consideration.

I think the solution will be one that allows the wing panel to flex easily from tip to tip, but remains more rigid from front to back. The wing should easily take the contour of the under camber as it is pressed into this position by the wing strut and the wing saddle. The it should also have enough stiffness that it doesn't buckle between plane and strut.

SlowBipe
Nov 16, 2012, 05:47 AM
I Used To Have More Free Time!
Would guy wires help?


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