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Old Mar 12, 2012, 07:54 PM
What goes up, must be repaired
Mid-Michigan
Joined May 2009
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What type of wing profile would work best?

I'm interested in building a 64" high wing FPV plane to help my local Search and Rescue team scan terrain quickly. The flight characteristics I'm looking for are as follows: 1. good lifting capability 2. slow speed flight 3. can be made of FFF or other foam materials.
I've been looking the the different flavors of KFm wing profiles. Would there be a better option? I'd like to hear your opinion.
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Old Mar 12, 2012, 08:31 PM
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Palmdale, CA
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What is your power and payload?
What optics?
What would be your search procedure?
And, have you done any aerial photography?
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Old Mar 12, 2012, 09:02 PM
Grad student in aeronautics
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What is the wing planform? (aspect ratio, taper ratio, sweep, etc.)
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Old Mar 13, 2012, 11:52 AM
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For resolution of ground objects, the AP platform will have to be flying fairly low.
With a good image resolver.
Here's some aerial shots... "Too high" is only about 400 feet for any ground detail.
The best AP platforms I've seen are the hexa-copters for stability and ability to carry large cameras.
They are noisy, though.
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Old Mar 13, 2012, 04:10 PM
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Paul, actually, about the comment on your 2nd photo... if you refer to the size of the shadow, it will be pretty much the same at whatever altitude the plane is. Though it will become less defined as it gets further from the ground, as the light from the sun comes from a disk that has an appreciable size in the sky rather than a point source, but it would need to be very, very high up for the shadow not to be noticeable. Sorry, I am being obnoxiously nitpick-y, I know...
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Old Mar 13, 2012, 05:21 PM
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Well yeah, the shadow will pretty much be the same at any distance, due to the distance to the sun.
But.... we can cleverly use the length of the shadow to compare to some other length which is not sun-dependent, such as the wheel ruts.. and then angle-side-angle our way through the trig..
Here's two examples...
In the second, I cloned the baseline measurement to get a nice wide angle..
I'm working on winkling out altitude from the second one..
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Old Mar 13, 2012, 06:06 PM
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Just make sure you don't use angle-side-side

(Ah, those were the good ole days)
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Old Mar 13, 2012, 07:26 PM
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Those photos were just some samples of what to expect with AP.
The OP hasn't returned... ???
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Old Mar 13, 2012, 09:35 PM
What goes up, must be repaired
Mid-Michigan
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Quote:
Originally Posted by Sparky Paul View Post
What is your power and payload?
What optics?
What would be your search procedure?
And, have you done any aerial photography?
I'm sorry I was MIA, got busy at work. The photos attached were very interesting, they all appear to be shot from a fairly high altitude. I'm thinking all want to fly lower (true field testing required of course)

Here are some answers to your questions:
Power and Payload: HXT 42-60 600Kv 43A Brushless Outrunner powered with a 4s battery, payload: 4s cell, CCD video camera, video Tx, 3s lipo to power video system
Optics: Sony HAD CCD video camera

Search procedure is yet to be worked out with the SAR team and Commander, I need to get a plane built and filed tested before we get that far. I have to crawl before I run.

I'd like the wing to have no taper and be easy to construct. We're talking easy construction (foam, glue, and CF) Any ideas?
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Old Mar 14, 2012, 05:44 AM
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Paul, you are quite right, I didn't realize you were estimating altitude based on the size of a known feature (as the plane shadow obviously is) on an image with a known field of view.
I was thinking in the simplistic way the cartoon shadows grow as the object projecting it is closing in, which is unrealistic but makes for good storytelling.
On the second one you can deduce altitude by measuring distance from both references and triangulation. Depending on how accurate you want to be, you can probably ignore a few distortions due to perspective, or interpolate them, to obtain the distance between the reference points. Also, you need to assume that the reference points themselves are at the same altitude.
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Old Mar 14, 2012, 11:03 AM
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Palmdale, CA
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Quote:
Originally Posted by topgun21 View Post
I'm sorry I was MIA, got busy at work. The photos attached were very interesting, they all appear to be shot from a fairly high altitude. I'm thinking all want to fly lower (true field testing required of course)

Here are some answers to your questions:
Power and Payload: HXT 42-60 600Kv 43A Brushless Outrunner powered with a 4s battery, payload: 4s cell, CCD video camera, video Tx, 3s lipo to power video system
Optics: Sony HAD CCD video camera

Search procedure is yet to be worked out with the SAR team and Commander, I need to get a plane built and filed tested before we get that far. I have to crawl before I run.

I'd like the wing to have no taper and be easy to construct. We're talking easy construction (foam, glue, and CF) Any ideas?
.
Almost any plane can carry that video system. It would be easy to buy an ARF and install the motor/battery (Lots of power there) and video system.
Otherwise the plain vanilla Clark-Y profile would be OK for a airplane of that type.. which is pretty close to a SIG Seniorita, which comes in a electric form, but much less power.
One of mine carries this external pod with the camera on a tilting mount, E-flite 25 motor, 3 cells, and is quite capable..
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Old Mar 14, 2012, 11:29 AM
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I don't have many aerial videos looking down.. but here's one.
Using a Canon Exilim at the widest lens setting.
Note how fast the ground goes by when it's low.
http://youtu.be/MOdJP_jOgss
.
Weather permitting, I might get another today, with a tilting camera mounted plane.
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Old Mar 14, 2012, 07:42 PM
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Check out this video.... The superiority of a copter over a plane is evident...
Moving slowly, and hovering.. with a image down link, should be what Topgun21 would find best...
http://www.youtube.com/watch?feature...&v=uHUPKYd_vLQ
.
Notice the shape of the copter on the roof....
.
And....
Absolutely superb...
http://www.panopixel.ro/multirez/bucuresti.htm
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Old Mar 14, 2012, 09:33 PM
What goes up, must be repaired
Mid-Michigan
Joined May 2009
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Thanks!

Thanks for your help Sparky. I love the Octocopters and agree it would be an idea platform, but I can't justify the cost. If the SAR group gets government funding or some corporate grants, I won't be able to fund that out of my pocket. I like the Sig plane, I was thinking the Clark Y profile would work too. I'll experiment on a 50% version and fly it and see what I need to adjust.
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Old Mar 15, 2012, 01:20 AM
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So many factors come into play with a design of this sort. For example how will you launch and retrieve it? Can you be sure there will be a clear road way which can be used as an impromptu operating strip or will you need to hand or rail launch it and belly flop in some nearby clearing?

What maximum range are you expecting the radio set to operate over? A conventional radio is good to about a half mile at moderate altitude. If you need more range then you'll need specialized equipment.

You'll likely want the model to break down for easier transport. So you'll want to select a design which lends itself to this design aspect.

Likely there's more that you can think of from having worked with the unit. These are just the factors that jumped into my head from reading and considering the design problems at first glance.

There's a lot to be said for the idea of a big flying wing that is a cross between a delta wing and a tapered and swept back flying wing. Such a shape will tend to be thick and rugged if operating into rough fields. Yet the large amount of wing area in a smallish span can make for lower flying speeds which translates well to possible hand launching or using a short bungee rail launch system for operating from tight confines.
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