First of all some background...
Having spent a good 2 years playing about with an Skywalker, Ursus and a Canon camera running CHDK, and designing my own uav, which actually flew recently ,I have come to the conclusion that flying wings may just be the best type of platform for short range aerial mapping tasks to create DEM, DSM models for GIS purposes.
The Skywalker was okay (but quite fragile, and now in pieces!), but I think it is too small to fit a roll gimbal on it. And I've found that if pictures are taken on a slight angle, it is very difficult to use software to tile them up nicely. this is my best effort, but far from perfect. The roads on the right do not line up as the camera must have been on a 45 degree angle when the picture was taken. (click for larger resolution) - It was taken using an ixus80 attached to an URSUS Airframe
Realizing that I need to use an airframe that can accommodate a stabilized roll gimbal, i started to design and build my own twin boom design. It took 6 months from initial design, to first test flight. It has a wingspan of 2.4m - AUW of 5kg, and a flight duration of around 30 minutes with 2 x 5000mah packs. However it needs a heck of a lot of room to take off and land, something i don't have in the areas i need to take photos.
Picture of twin boom plane...
What are peoples experiences with using flying wings for this reason? I have the following types of flying wings, and wondering which one is the best to begin with?
I have been using the 60" wing to test the APM2 and 3dr radios. And was using the URSUS (now in pieces after a nasty crash!) as a test platform to practice with the Canon CHDK Kit.
Here's a few pictures of the wing and camera....(click images for larger version.)
My question is how straight forward do you think it is to fit a roll stabilized gimbal to any of the above airframes?
nice setup, If you can Balance all these on a wing, you will be my hero... :)
For the cam:
The most common and safe setup to add a cam to a wing is this: (i am sketching it because my eng, will take me a month to describe it)
the foams height should be enough so, when the lens is retracted, it still stays inside the wing. no need of skids etc. If you want to be extra safe, a piece of creal plastic will keep your cam protected from dust and small rocks. (cd cases are perfect)
Cheers for the info James, I have been busy trimming servo wires etc for a neat installation. Unfortunately, due to the thickness of the wing, the Camera lens will stick out below the surface of the wing by about 10mm. I will need to think Carefully how to protect it... I am going to post some pictures shortly...
I've almost got this ready for the first map test. The wing and Canon Camera and 2200mah flight battery weight 1.6kg. A bit lighter than the last plane i made!
I like the simplicity of this idea. Not done any motorcalc work yet, but If i am not getting enough power to last for a 15km flight, I will look at the power system. the motor and prop on there at the moment was already on the wing when i used to use it for fun...
Everything fits nicely....
A close up of the insides..hopefully nicely protected..
Next up, build a ply hatch, work out where to place the 3DR Radio, and then do test flight....
Right then, here is my first stab at using motorcalc
66 inch wing
props - recommended is apc 10x5 / apc 10x7 (as mentioned on motor page)
i'm not really getting anything that real back from motorcalc... could somebody take a look at the figures i've input - and see if there is anything glaringly obvious I have done wrong?
Is anyone able to help with the motorcalc issue posted above? does anyone use the software to predict flight times/performance?
In other news, I have just had a first attempt at creating a DEM from a point cloud I generated on Photosynth from a set of images i took a good few months back. Got to do something when the weather is too rubbish to fly! fingers crossed first APM2 flight tomorrow with wing..
Does anyone know how to overlay hi-res pictures on top of a mesh?
Good morning Rich,
It seems that your motor its a bit light for your setup (72gr) and the motor calc data, must be outdated or something, check the resistance (0,0095 Ohm) i think its 0,19. further from my calc, i see also that 10x7APC E stalls... Try a smaller pitch, like 10x6, or 11x5.5. if you browse thru the BRC site, at esc-motor combos, they give different data: "*Prop range:
3S LiPo APC-E 10 x 5, 10 x 7, 11 x 5.5"
As for the mesh.. i could help you out with the basics, but its a very advanced procedure and we will need a dedicated forum for that... try this guide: http://palentier.blogspot.gr/2010/12/how-to-create-digital-elevatio...
Would you recommend a motor possibly in the region of 100g or more? I do have a few brand new motors lying around.....all larger than the 72g motor i have on there now
RE: the mesh, I have gotten to the stage where I can remove the points that were creating thebig white cloud beneath the surface, deleting unwanted vertices. And am trying to work out how to do the following...
I'd like to know what software i need to be looking at to achieve the above tasks... that would be a big help//
Yes, 100gr rank would be great, the 2814 seems perfect, you will have about 1/1 thrust/weight...
Mesh, overlaying etc..
You dont need gps cam to georeference or geotag. To geotag you can use mplanner.
1. To make the point cloud and overlay the stiched mosaic, you can use hypr4d, it gives very good results fo free, also it gives you a hires downlodable version, for meshlab
2. To georeference the above results you will need somekind of gis soft, like global mapper, arcgis etc. And tie known points on image with known points on a hires basemap (you can try with google sat). For more accurate results, you will need ground control points.
Wish you a good maiden and llook forward for the results.
First flight of the 66inch wing with camera equipment - The plane flew ok at the estimated CG, I only flew on manual and stabilize. However I think your right James, I definitely need to change the 2217-9 motor for the 2814. It was very sluggish on full power.
It's been overcast cloudy all day - and the photos came out very dark indeed. I used 1/330th shutter speed. Which is apparently too quick for a cloudy day.
Sample Meta Data from one of the photos...
Here are some of the highlights.... lol - not quite good enough to produce a DEM or a mosaic.
Some Local Scenery
Hmmm - Looks like i'll need to add more foam to the camera mount and increase the shutter open time.
After a bit of tinkering, I have re-learnt how to use the CHDK on the Canon Camera, and have also upgraded the motor to the BRC 2814-8t - Combined with a 11 x 5.5 prop that should give 15 minutes flight time at 75% throttle. Motorcalc is reporting 25mph flight speed @75% throttle for 24 minutes - a 300w motor and 2200mah battery. I somehow cannot see that being true!
Fingers crossed for some good weather... i'll be using ISO400 this weekend and setting focus to infinity! I've been playing with the Dataset i took on the local cliffs, heres the model as viewed with a surface shader...I like how the relief is so detailed - Just upgraded my camera, only slightly to an ixus 90, 10mpix, as opposed to 8mpix. mainly bought it as a backup.
Cheers, I'm hoping to do another pass over this area... the DEM was created form lots of photos which were taken at very different angles and altitudes,.Hopefully this time the plane will cover a nice clean square km in a lawnmower pattern so i can the beach, car park and sea in shot.
Still trying to work out how to overlay the photos on top of the DEM without xyz and geo data! it's a challenge!