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Feb 07, 2016, 02:07 AM
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Build Log

Skywalker X8 for Aerial Mapping


I recently completed a Skywalker X8 build for aerial mapping and here are the details of my build:

Components:
Sony RX 100 with Gentwire trigger running off flight controller (this will be replaced by Sony A6000 on 2 axis gimbal)
3DR Pixhawk flight controller, telemetry radio, GPS, airspeed kit, OSD
Immersion RC 5.8g 600mW VTX
Scorpion SII-3020-780KV V2
13 x 6.5 Aeronaut folding prop
Hobbywing 60A ESC
Hitec HS85s on elevons
4S 10,000mAh
Fatshark FPV camera
ABS plastic nose cover


Main modifications are as follows:
2 x full length 4mm x 4mm carbon box section stiffening spars in each wing, recessed into lower surface
12mm OD/10mm ID bi-directional fibre carbon tube in fuse and wings as an outer sleeve to the stock 10mm OD carbon wing joiner
Balsa elevons

Build was fairly straightforward and I though the parts fit was not too bad, but my specific mods did require quite a bit of extra build time (total was around 70 hours). I thought the stock elevons were totally inadequate and I cannot see how these could work with all that flex.
The space in the fuse is cavernous which makes component installation and wiring so much easier. All up weight including Sony RX100 is 3.3Kg, Launch method is bungee and ramp.

Jacques
Last edited by Jacques.Eloff; Oct 14, 2016 at 03:41 AM.
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Feb 07, 2016, 04:03 AM
FPV in Hawaii
iskess's Avatar
Excellent build. What do you plan to use for your 2 axis gimbal?
Feb 07, 2016, 06:26 AM
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Jacques.Eloff's Avatar
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Quote:
Originally Posted by iskess
Excellent build. What do you plan to use for your 2 axis gimbal?
Thanks!

As for the gimbal, I like the look of this: http://www.skyviewcustoms.com/2-axis...ng-gimbal.html

Jacques
Feb 07, 2016, 07:32 AM
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Nice build! Keep us updated!

Do you have a link for the 3D printed pitot holder?
Feb 07, 2016, 08:10 AM
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Jacques.Eloff's Avatar
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Quote:
Originally Posted by marbelo
Nice build! Keep us updated!

Do you have a link for the 3D printed pitot holder?
Thanks!

Here's the link for the pitot: https://www.shapeways.com/product/7T...ionId=57935984
Since this one is for Eagle Tree, you will need to trim one of the metal tubes on the 3DR pitot, but very easy. There's another one by the same guy which fits 3DR pitot, but the mount is shorter and not suited for foam models that have thicker fuselage walls.

Jacques
Feb 07, 2016, 08:14 AM
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wazoo22's Avatar

Nice build log. Could use a bit of text describing your observations along the way.


questions:
Most of us have our ways of protecting the foam from damage- some cover with film, some sand and glass, some glass just the leading edge, etc.
Do you plan to do this? And if so, -how? Particularly for a working aircraft, durability (and presentation) will suffer if not.
Where did you get the nice ABS nose cover?
Many motors have a big bearing in the business end to carry prop loads, and a small bearing in the other end. |If you use those in a pusher configuration, the prop is now on the end with the small bearing-a recipe for early failure. I speak from experience . Three flights, and the howling bearing monster arrived. My first choice, the howling SK3-3542-800 is now replaced with a true double-bearing motor. Frankly, I'd not save money on the motor here- lotta nice equipment depending on the rear bearing being robust enough to handle it.
If you already know all this, ignore me.
Feb 08, 2016, 12:42 PM
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Quote:
Originally Posted by Jacques.Eloff
Thanks!

Here's the link for the pitot: https://www.shapeways.com/product/7T...ionId=57935984

Jacques
Thanks a lot!
Feb 09, 2016, 03:43 PM
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Jacques.Eloff's Avatar
Thread OP
Quote:
Originally Posted by wazoo22
questions:
Most of us have our ways of protecting the foam from damage- some cover with film, some sand and glass, some glass just the leading edge, etc.
Do you plan to do this? And if so, -how? Particularly for a working aircraft, durability (and presentation) will suffer if not.
Where did you get the nice ABS nose cover?
Many motors have a big bearing in the business end to carry prop loads, and a small bearing in the other end. |If you use those in a pusher configuration, the prop is now on the end with the small bearing-a recipe for early failure. I speak from experience . Three flights, and the howling bearing monster arrived. My first choice, the howling SK3-3542-800 is now replaced with a true double-bearing motor. Frankly, I'd not save money on the motor here- lotta nice equipment depending on the rear bearing being robust enough to handle it.
If you already know all this, ignore me.
Hi – the motor issue your raise is an interesting point and has made me think. I agree that Turnigy is on the budget end so I changed to Scorpion SII-3020-780KV V2. This did require me to prop down to a 13" prop with lower pitch, but no major problem

As for toughening up the airframe – the bottom is glassed, but the rest is all bare foam.

Thanks,
Jacques
Last edited by Jacques.Eloff; Feb 11, 2016 at 02:27 AM.
Feb 09, 2016, 05:47 PM
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gjhinshaw's Avatar
I am using a SUNNY SKY motor and so far has been the best combo for this plane and the gear I run! It's like 56usd and to me worth every penny! Take off is at HALF throttle!




Quote:
Originally Posted by Jacques.Eloff
Hi the motor issue is an interesting point and has made me think. I agree that Turnigy is on the budget end so I may consider changing this. Regarding the bearing issue I would have thought it is ok in this configuration, because if you have a look at the picture of the laser balancing you will see that it can take the prop adaptor on that end (it has 3 small screw holes to mount it). However, in my case I pushed through the shaft and mounted the Aeronaut prop adaptor. What motor would you recommend if you think I am going to have issues with the bearing. I would need around 650KV.

As for toughening up the airframe the bottom is glassed, but the rest is all bare foam.

Thanks,
Jacques
Feb 09, 2016, 07:25 PM
FPV in Hawaii
iskess's Avatar
Which sunnysky motor? What prop and battery with it?
Feb 10, 2016, 04:34 AM
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wazoo22's Avatar
Quote:
Originally Posted by iskess
Which sunnysky motor? What prop and battery with it?
I strongly suggest that you subscribe to eCalc , if you haven't already. Please tell me if all this is old hat--I won't be insulted and I've got other things to do today.
Have some fun with it. It's as accurate as you will find in an "estimator" , but not perfect.
I ran your numbers for the weight and power you have planned, and they are the first 2 panels.
Then I ran some other numbers, using a Sunnysky, that looked interesting.
Useful assumptions:
1) It will end up heavier, once the goodies are installed, and
2)
Try this:
Assume the Lift to drag ratio for the final bird is around 8/1. 6/1 if you've got that gimbal installed. Find your way to the line that shows thrust of 1/8th of the gross weight (412g.). If life were perfect, that line shows the grams per watt, and much more, that you need just to just sustain flight.
Now double it (the thrust).
This is the number (the line) I use to estimate real-time performance at an economical cruise. Enough power to climb moderately, and so that I don't fall asleep at the helm. This is for an aerodynamically clean bird. Perhaps a good number for mapping? You decide, but in my opinion, only flight tests will get that number really nailed down.
If Turigny's numbers can be believed, your choice appears a good one, but the SS is usually more efficient. In practice, I find Turnigy to be rather optimistic. Sunnysky also, but much less.
Both motors' numbers look good. That leaves the bearing question.
Personally, I'd try it (the SK3) -not too expensive- but I'd change out the front bearing at least (Boca Bearing) for a better one, and do my own balancing. I typically choose the Sunnysky or an appropriate Scorpion, etc.
As for the foam, -I'd cover it with something. 3mil film overlapped on the leading edge works for me, if I don't glass the whole wing, which I usually do.
Last edited by wazoo22; Feb 10, 2016 at 04:58 AM.
Feb 15, 2016, 09:45 AM
Registered User
Quote:
Originally Posted by Jacques.Eloff
Thanks!

As for the gimbal, I like the look of this: http://www.skyviewcustoms.com/2-axis...ng-gimbal.html

Jacques
Save yourself a few bucks for a completely assembled version from a different company. Works well.

http://appliedaeronautics.com/Flat-M...imbal_p_4.html
Feb 15, 2016, 09:54 AM
Registered User
Quote:
Originally Posted by Jacques.Eloff
I recently completed a Skywalker X8 build for aerial mapping and here are the details of my build:

Components:
Sony RX 100 with Gentwire trigger running off flight controller (this will be replaced by Sony A6000 on 2 axis gimbal)
3DR Pixhawk flight controller, telemetry radio, GPS, airspeed kit, OSD
Immersion RC 5.8g 600mW VTX
Scorpion SII-3020-780KV V2
13 x 6.5 Aeronaut folding prop
Hobbywing 60A ESC
Hitec HS85’s on elevons
4S 10,000mAh
Fatshark FPV camera
ABS plastic nose cover


Jacques
Something you may want to consider, especially if you want to do this commercially and are budget conscious like me. I would use cheaper cameras such as the standard Canon s100, s110, etc. as they can be purchased for around $125 used on Ebay. The cameras are very durable and can easily be modified to accommodate near infrared (NDVI) light. The also have decent built-in GPS and support KAP/CHDK scripting.
The GPS and KAP/CHDK was key for me because services such as MapsMadeEasy or DroneDeploy become a simple upload and process your images task and not get GPS log data from the flight controller, add it to images via external software, upload and process. KAP/CHDK scripting is used to trigger interval shots and adjust camera settings automatically without adjusting Pixhawk settings. I personally operate a FX-61 because it's just easier to transport and I'm getting around 650 acres per one hour flight on an 8000 mAh 3s lipo.

Just a lil' something to consider.

DREi
SkyAerialSolutions.com
Last edited by itsdrei; Feb 15, 2016 at 10:10 AM.
Feb 15, 2016, 04:06 PM
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Jacques.Eloff's Avatar
Thread OP
Quote:
Originally Posted by itsdrei
Something you may want to consider, especially if you want to do this commercially and are budget conscious like me. I would use cheaper cameras such as the standard Canon s100, s110, etc. as they can be purchased for around $125 used on Ebay. The cameras are very durable and can easily be modified to accommodate near infrared (NDVI) light. The also have decent built-in GPS and support KAP/CHDK scripting.
The GPS and KAP/CHDK was key for me because services such as MapsMadeEasy or DroneDeploy become a simple upload and process your images task and not get GPS log data from the flight controller, add it to images via external software, upload and process. KAP/CHDK scripting is used to trigger interval shots and adjust camera settings automatically without adjusting Pixhawk settings. I personally operate a FX-61 because it's just easier to transport and I'm getting around 650 acres per one hour flight on an 8000 mAh 3s lipo.

Just a lil' something to consider.

DREi
SkyAerialSolutions.com
Hi, yes, I am well familiar with KAP CHDK script, I actually have an S100 and using it in a Skywalker X5. My only problem is that I cannot get it to fire at less than +-3.5 sec intervals. At 120m and 14m/s speed, that is not enough overlap. How are you getting around that?

On the other can, Sony can fire much more rapidly.

Jacques
Feb 16, 2016, 09:46 AM
Registered User
Quote:
Originally Posted by Jacques.Eloff
Hi, yes, I am well familiar with KAP CHDK script, I actually have an S100 and using it in a Skywalker X5. My only problem is that I cannot get it to fire at less than +-3.5 sec intervals. At 120m and 14m/s speed, that is not enough overlap. How are you getting around that?

On the other can, Sony can fire much more rapidly.

Jacques
Hmmm...I'm not doing anything special actually and the only difference I see is that I'm flying at 10 - 12m/s speed, yet our altitudes are the same.


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