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Old Jan 18, 2009, 10:14 AM
Begin with end in mind...
power's Avatar
Eagle Lake, Minnesota
Joined Apr 2003
5,599 Posts
Discussion
Yet another flying chunk O' foam....

last week and decided try another design change. It appears that the ORB has the smoothest video to date. I feel this is due to a couple things. One...more mass hanging low. This will not allow quick bumpy rotation as the weight hanging wants to stay hanging. Two...overall size/mass.

With this in mind, I slapped this cute little feller together to see what happens. The fuse is freaky tall and all the weight but the motor will be at the bottom. This plane also has a new foil onboard. This foil is a modified Solution foil. It now has "undercamber". With this mod I lost 3 oz of weight off the wing. I did leave the thicknesss of the foil so I could use my spar on top method and the strength would remain. The fuse is made from 1 1/2 in beaded foam sheeted with 3mm Depron. The stab also has a few more squares than the Solution. The Axi 2820-14 will be used for power. Though a lot larger than the Solution, this bird has a lower wing loading. I am hoping for a bit more lift out of the new foil if you add the extremely low wing loading and a calm day this plane should be the slowest bird I have to date.

Folks...this is my last attempt at trying to get the smoothest video possible with this size plane. Leif, my partner in crime says we need to go the other direction...BIG!! After thinking a while and watching Perftech's large craft. I have decided to hit the drawing board. I have a design started that will have a wingspan over 10' a cord of 27" and will have Solution roots. Being a toolmaker I do appreciate the work involved with the Perftech plane However, the average builder does not have the tooling or the material availability to make the parts required.

My goals are to make this new monster from materials readily available from hobby stores or lumber yards and... Now here is the tough one...I am planning on transporting this beast with my VW Passat. I have several simple "light" ideas churning that will allow the breakdown of the wing as well as the fuse. I have a few details to mull over then I will begin construction. Until then... on the first nice day I will test fly this ugly critter and see how it works. Here are some pics/numbers....

BTW, I had to borrow my wifes work bench for some of the pics...

Mike


Original Solution:

WS 72 in
Wing area 936 sq in
AUW with 3s 2100 and A-640 49oz
Wing loading 7.5 oz/sq in
Motor AXI 2814-16


This plane:

WS 80 in
Wing area 1190 sq in
AUW with 3s 2100 and A-640 56.8 oz
Wing loading 6.5 oz/sq in
Motor AXI 2820-14
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Last edited by power; Feb 11, 2009 at 05:22 AM.
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Old Jan 18, 2009, 10:27 AM
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Steve Mills's Avatar
England
Joined Dec 2005
308 Posts
Interesting aerofoil, can you tell us a little of how you arrived at this section or is it just experimental?
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Old Jan 18, 2009, 10:40 AM
I fly with my little eye
Swanlander's Avatar
Lancashire, England
Joined Jul 2005
1,832 Posts
Mike,

Beautifully engineered as ever. I am sure she will fly well. She deserves better than to be called a lump of foam..Abs-ORB? (Soaks up the solution).

Cheers

Andrew

PS: May I offer a suggestion? The pictures don't show any webs between your upper and lower spar strips...If you go larger I would add some for peace of mind. Minimum additional mass, but you get an immensely strong I beam.
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Old Jan 18, 2009, 11:33 AM
Begin with end in mind...
power's Avatar
Eagle Lake, Minnesota
Joined Apr 2003
5,599 Posts
Quote:
Originally Posted by Swanlander
Mike,

Beautifully engineered as ever. I am sure she will fly well. She deserves better than to be called a lump of foam..Abs-ORB? (Soaks up the solution).

Cheers

Andrew

PS: May I offer a suggestion? The pictures don't show any webs between your upper and lower spar strips...If you go larger I would add some for peace of mind. Minimum additional mass, but you get an immensely strong I beam.
Thanks Andrew,

LOL, clever name While I have thought about the web... only for a moment I do plan to stay with the same spar config. There will no doubt be changes as far as width and thickness goes for the caps as well as other structural areas, but I really want to see how far this spar method will go. I have been impressed with how reliable/simple this spar system is to date. If we dont give it a go on a larger scale we will never no the limits. Besides...all that foam will make for an incredible snow storm if something fails


Steve, The airfoil is completely experimantal. I have know idea if it will be better or not but I figure why not try.


Mike
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Old Jan 18, 2009, 12:04 PM
Registered User
Cumbria in the U.K
Joined Jan 2008
1,920 Posts
Would flaps help ?
Full width flaps should slow it down as well as aiding lift.

Great design though.
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Old Jan 18, 2009, 01:10 PM
Begin with end in mind...
power's Avatar
Eagle Lake, Minnesota
Joined Apr 2003
5,599 Posts
Quote:
Originally Posted by sparklet
Would flaps help ?
Full width flaps should slow it down as well as aiding lift.

Great design though.
Thanks, as with my other "AP" designs I stay away from ailerons as well as flaps. This is not to say they would not aid in certain areas I just do not want the complexity/extra weight in the build.

Mike
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Old Jan 18, 2009, 01:17 PM
Fly Big, Low and Slow....
Alpina540's Avatar
USA, VA, Wicomico
Joined Aug 2008
1,358 Posts
Very Interesting Mike I am thinking of building a huge 10' foamy too!

Boy your numbers for AUW make my solution look like a pig!

-Anson
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Old Jan 18, 2009, 03:00 PM
No thrust...It'll bust...
troynh's Avatar
Troy, NH
Joined Sep 2006
4,314 Posts
Nice looking airfoil Mike!

-Tim
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Old Jan 19, 2009, 05:19 PM
Kite flying SCRAPS member
GliderGuideMan's Avatar
Hampshire, UK
Joined Apr 2004
974 Posts
Hi Mike - what do you use as a power supply on your wing cutter? I have a 12v train transformer which works well for the bench cutter. It just doesn't cut the mustard (or foam for that matter ) when I go over 18" of wire. I am guessing I would need to go to 24v but I can't seem to find a ready made adjustable power supply that I can afford at that voltage

Keep up the good work and I am looking forward to Ultralight plans

Cheers
DaveB...>
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Old Jan 19, 2009, 06:21 PM
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John O'Sullivan's Avatar
Nova Scotia Canada
Joined Jan 2004
1,016 Posts
Mike:
Your continuing development of your design is being conducted in a logical, systematic fashion and you have added a wealth of information to the simple practical foam airphoto airplane. I feel sure that this model will be as successful as earlier versions.

As Swanlander suggested, I had also thought that a light vertical web could be incorporated without adding any appreciable weight. In the past, I have simply cut a vertical slit at mid spar location and included a 1/32 or in your case a 1/64" ply web.
Certainly stiffens up vertical wing flexing.
On a model of this size and wing loading there would be little or no need for flaps. The extra complexity would be un-necessary. I've been flying an aileron and flapped version of my Eyespy for the past year and found that the simple approach is the best.

Keep up the good work.
John
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Last edited by John O'Sullivan; Jan 19, 2009 at 07:32 PM.
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Old Jan 19, 2009, 07:43 PM
Begin with end in mind...
power's Avatar
Eagle Lake, Minnesota
Joined Apr 2003
5,599 Posts
Quote:
Originally Posted by GliderGuideMan
Hi Mike - what do you use as a power supply on your wing cutter? I have a 12v train transformer which works well for the bench cutter. It just doesn't cut the mustard (or foam for that matter ) when I go over 18" of wire. I am guessing I would need to go to 24v but I can't seem to find a ready made adjustable power supply that I can afford at that voltage

Keep up the good work and I am looking forward to Ultralight plans

Cheers
DaveB...>
Hi Dave, don't laugh at my ugly power supply but here are some pics of the old thing. It was slapped together 20 yrs ago and is still going strong It is just an old metal box with a 24v transformer mounted and a dimmer switch from Menards. There is a red light on the top to tell me when it is on. I do have a fuse link on the back but I have it disabled at the moment. There really is not much to it and it has plenty of poop! My bow will cut a 42" core at less than half throttle

Oh, sorry I have not got to posting the UL plans yet I am still waiting to test the larger stab. I did steal the RX out of it for this latest bird but I will get it in the air sometime soon. I can post what I have I just have to get my butt in gear and do it



John, thanks for the kind words I will evaluate the web/spar when I start the wing. I did use this method you guys are speaking of back on the "original" Beast.

http://www.rcgroups.com/forums/showp...&postcount=182

It is very strong. After omitting it on the later designs I have not seen anything that tells me I need it yet. I have yet to experience any wing flex but this is on sub 5lb ships. I will be looking at 10+ on this next bird so things will no doubt change a bit.

Mike
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Old Jan 20, 2009, 08:42 AM
Kite flying SCRAPS member
GliderGuideMan's Avatar
Hampshire, UK
Joined Apr 2004
974 Posts
Mike thanks for the explanation and pictures - looks like a trip to my local electronics store is in order

DaveB...>
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Old Jan 20, 2009, 04:08 PM
Pull out early!
DiveBombDave's Avatar
Lexington, KY
Joined Jan 2005
1,956 Posts
GGman- You have to either up the voltage for your big bow, or increase the wire gauge, or both. I run my 18" table hotwire cutter on a 12v wall supply, but my big 52" bow runs off 5 or 6s lipo. It is a pain that you have to monitor your packs, but the draw is only a few amps so it's not harmful to them. Maybe I can buy another 12v supply and wire them in series for 24v?

Mike- Kudos!

Dave
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Old Jan 21, 2009, 05:21 AM
Begin with end in mind...
power's Avatar
Eagle Lake, Minnesota
Joined Apr 2003
5,599 Posts
Well the weather shaped up a bit and we got a chance to take this thing for a spin. The plane was a tad tail heavy for the maiden so on the down wind turns the plan squats quite a little. Once turned into the wind the plane is like flying a balloon In the video you cane see it just hangs above the trees. The throttle settings during the entire flight are minimal. After watching the video I did not see any extensive wing rocking in the wind. I need to make a few adjustments and fly it some more but it does seem to stay more level than my other models. I don't know if the new foil helps or not but it does fly slow. If anything it does not fly worse and I lost three onces

Here is the maiden video... I went out of the box a bit and threw in a bit of country music I did decide on a name.... Let's call it the CREEPER

http://www.mvqf.com/power/Beast/Creeper.wmv


Mike
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Old Jan 21, 2009, 12:20 PM
I AP'd myself again......
aviatordave's Avatar
Yawn....Iowa
Joined Mar 2005
2,500 Posts
I finally got to watch the movie after dl'ing it this morning. Floats very nicely.

I know you all discussed this before.... But would there be anything to lose if you opened a few of the lightening holes up on the fuse for air to pass by? or would it not matter to help decrease the weathervane effect? There is prob a scientific theory behind it, most planes I fly seem to weathervane into the wind.

TIA - Dave
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