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Old Jun 10, 2012, 04:16 PM
free bird
Mickey D's Avatar
South Africa, GP, Johannesburg
Joined Aug 2011
169 Posts
Buckminster fuller's hollow geodesic dome comes to mind with this structure. enjoy the build.
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Old Jun 10, 2012, 07:45 PM
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Warren B's Avatar
Mt Evelyn, Melbourne, OZ
Joined Dec 2008
651 Posts
Well, spurred on by this thread, I had another go at Windbag yesterday.
Original faster PAW 55 fitted, spinning a 7x3 for maximum slipstream over the tailerons.
Success! (kind of).
It is still a challenge to fly, hard to tell how much roll I have and of course will not turn at all if not rolled.
Needs quite a lot of control movement, about 1" each way for aileron component and about 1/2" for elevator.
Balance is about 11" back along the 35" fuselage (mine is slightly scaled up).
Looks great doing a long fast pass.
Even glides a bit, with at least some control.

Did one over banked turn which resulted in a downward loop - but it made it!
Altogether very amusing.
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Old Jun 10, 2012, 07:54 PM
The dog ate my clearance
brokenspar's Avatar
Joined Jan 2004
1,058 Posts
That's good information, Warren. What is the all-up weight? For level flight, how much nose-up angle do you need? Thanks.
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Old Jun 10, 2012, 10:45 PM
Since 1952
Harry D's Avatar
Canada, AB, Edmonton
Joined Oct 2004
1,329 Posts
Quote:
Originally Posted by Warren B View Post
...a bit slow on elevator, requiring most fo the available "up" to keep flying.
Warren, the small-scale plan in your Post #22 seems to show a huge amount of negative incidence ("up elevator") for the horizontal stab. Did you incorporate that in your build?

The reason I ask is that some time ago I started the "lazy man's" (part foamie) Martian Spaceship featured in the May 2010 Q&EF, but it's been on hold for a while. This thread has inspired me to get back at that, and I was wondering whether I should put some negative incidence in the stab to help provide the (fairly high) angle of attack that this thing would presumably need to fly at.

I realize that a free-flight Windbag is not the same as an R/C Spaceship, but in view of your experiences that might be worth considering.

Any thoughts, anybody?
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Old Jun 11, 2012, 01:42 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
Joined Nov 2008
3,688 Posts
Quote:
Originally Posted by Warren B View Post
Well, spurred on by this thread, I had another go at Windbag yesterday........Looks great doing a long fast pass.
Even glides a bit, with at least some control......Altogether very amusing.
Warren: Any video? I can remember my older brother starting (and never finishing) one of these in the early 70s......I remember the purple and blue tissue covering with a shudder!
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Old Jun 11, 2012, 04:57 AM
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Warren B's Avatar
Mt Evelyn, Melbourne, OZ
Joined Dec 2008
651 Posts
Hi Brokenspar
My Windbag all up weight is about 13 1/2 ounces.
The amount of incidence needed is very speed dependent.
Needs more up trim at launch, but that needs to be reduced as speed increases and it seems to get "up on step" like a hyrdoplane.
I use a 3 position flap switch to give me three different elevator trim settings, much quicker than using trim.

Are you going with rudder elevator or tailerons?
Rudder always worried me as it is all above the axis and tend to roll the cylindrical body the wrong way for the turn.
But then again tailerons have their quirks too.

Harry, mine has all the negative elevator incidence as per plan. Does seem to need it.

Colonel, No video as yet, but maybe I can convince a camera person to join me one day.
I might try the video glasses again.
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Old Jun 11, 2012, 09:02 AM
The dog ate my clearance
brokenspar's Avatar
Joined Jan 2004
1,058 Posts
I'm planning on tailerons. It's interesting that the Windbag plan specifies a large amount of stab incidence while the Spaceship has zero. Trim sessions might be exciting. Warren, does your Windbag fly in a nose-high attitude?

Most of the top-side framework is now in place. This fuselage has taken an enormous amount of cut-and-fit work. It's those "fiddly bits" again. That always sounds like something one would order at a London pub..."I'll have the fish and chips, a pint of Guinness, and a side order of fiddly bits...."
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Old Jun 11, 2012, 09:42 AM
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Vrated's Avatar
United States, UT, Marysvale
Joined Aug 2004
1,113 Posts
Looks like it is comming along really good. Kinda reminds me of something that should go into the bomb bay compartment of the "Enola Gay"
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Old Jun 11, 2012, 11:30 AM
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Gluehand's Avatar
The windy west coast of Sweden
Joined Sep 2008
3,027 Posts
Quote:
Originally Posted by brokenspar View Post
It's interesting that the Windbag plan specifies a large amount of stab incidence while the Spaceship has zero."
The "soft wire" shown on plan, indicates that the designer assumed some bending in order to acheive the required 'decalage'....

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Old Jun 11, 2012, 01:20 PM
Stupid Gravity!
Franny B's Avatar
Arvada, Co
Joined Feb 2006
843 Posts
Looks great Pete! Can't wait to see it in the air.

Maybe you could use that gyro you used in the Blazer? Might calm down the roll a bit.

Franny
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Old Jun 11, 2012, 03:33 PM
The dog ate my clearance
brokenspar's Avatar
Joined Jan 2004
1,058 Posts
It might come to that Franny. I'll just have to fly it and see.

Fuselage is essentially completed, awaiting tail and motor.
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Old Jun 11, 2012, 05:04 PM
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E-Challenged's Avatar
United States, CA, Garden Grove
Joined Oct 2000
12,199 Posts
I think that the "dutch roll" action is from too much " dihedral" from the lower body shape. when in lifting attitude. Maybe it can't be corrected, looks kinda cool. Always liked the red and silver motif. Seems like a large diameter e-prop might improve rudder and elevator authority over the 1/2 glow versions.
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Old Jun 11, 2012, 06:01 PM
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ColinNZ's Avatar
Auckland New Zealand
Joined Aug 2004
933 Posts
That framework is a work of art seems a shame to cover it.

Colin.
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Old Jun 11, 2012, 07:26 PM
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Warren B's Avatar
Mt Evelyn, Melbourne, OZ
Joined Dec 2008
651 Posts
[QUOTE=brokenspar;21864051]I'm planning on tailerons. It's interesting that the Windbag plan specifies a large amount of stab incidence while the Spaceship has zero. Trim sessions might be exciting. Warren, does your Windbag fly in a nose-high attitude?

Hi brokenspar
Until it gets up to speed, the nose up might be 5 degrees.
When it's up to full speed (the PAW 55 is a good one) it's still positive but maybe only 2 degrees.
Certainly less nose up than I expected.
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Old Jun 13, 2012, 09:18 AM
The dog ate my clearance
brokenspar's Avatar
Joined Jan 2004
1,058 Posts
Thanks for the encouraging words.

Installed a balsa equipment platform along the fuselage center. A pair of micro servos will operate the tailerons. Fitted a plywood firewall and trial mounted a motor. Power-wise, I have several small brushless motors that might do the job. One is about 45 watts, the other about 70 watts. These are Hong Kong specials of about 3/4 ounce and 1 1/4 ounce respectively. Battery will be a two or three cell lipo. As the build progress, I'll move things around on the platform to establish CG.
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