Hey everyone, so I don't have the APM tuned very well but at least its hitting waypoints and holding altitude and airspeed. I decided to get it flying and see just how long it would go. Here it the result:

here are the Tlogs

this is the equipment list:

Techpod Kit

Foxtech 370kv motor

APC 12*8 prop

Castle ice2HV 40 ESC

2x Zippycompact 6s 5000 mah lipo

APM 2.5 + telemetry + airspeed sensor

AttoPilot 45A current sensor

6x Hitech 65-hb servos

So whats next for the techpod? well, I will refining the gains. After I have it flying smoothly, I have a setup in the works that will be pushing flight times over 5 hours. Stay updated on the lated techpod news @ hobbyuav.com


Views: 12212

Comment by Reto Buettner on July 31, 2013 at 6:29am
Comment by Tommy Larsen on July 31, 2013 at 6:33am

Ok, thank you Reto :)

Comment by wayne garris on July 31, 2013 at 11:43am

as for propeller efficiency, give me a single bladed propeller of infinite length and then I'll be happy. here are some pictures of how the batteries fit in there. I carved away the foam until the battery was about 1/4 inch from the second bulkhead. I also had to cut a large notch in the first bulkhead so the batteries will fit through it. another big consideration is CG. I put the rudder servo and the VTx in the tail to counter balance the big bats.

Comment by cedivad on July 31, 2013 at 3:31pm

What are the specs of the motor you would reccomend me? 370kv and 700W? (after your tests would you change something?)

Comment by Reto Buettner on July 31, 2013 at 11:41pm
@Wayne: Let me know, once you have developped your highly efficient single bladed ultralong prop! Until then I will stick to the nowadays best solution for long endurance and long range, namely a relatively small prop with high pitch ...

Comment by wayne garris on August 1, 2013 at 12:01am
Larger props are more aerodynamically efficient then smaller ones. There are about a billion links I can give you that can back up this thesis. Here is just one

Comment by wayne garris on August 1, 2013 at 3:20am

That being said, of course that is a theoretical extreme example. This of course has to be fully integrated into the rest of the system. The propeller must match the power system both must be matched to the mission profile. You are flying a different mission profile then what the techpod was designed for. You are going for maximum distance, the techpod is designed for maximum time aloft. we beat each other pretty handily in our intended mission profiles.

I postulate that if you take a given motor, rewind it with a lower Kv, give the motor higher voltage and spin a bigger/steeper prop, you will end up with a more efficient set up. the problem is that this breaks down in the high speed case because the prop will inevitably be turning too slow for the speed.

I really think your design is cool and congrats on the 100k badge! and yes people do use single bladed props;-p

Comment by wayne garris on August 1, 2013 at 3:28am

check this out. this place makes single bladed props for speed rc F2A competition I think this would make a very interesting experiment.

Comment by NorthSweden on August 4, 2013 at 10:22am

Sweet setup:P Just ordered mine:P Ditch a battery and go solarpowered:P


Comment by Reto Buettner on August 5, 2013 at 1:20am

Thanks for your thoughts. I agree there is a difference between optimizing on long endurance (time aloft) and long distance. For long endurance a slightly smaller pitch might pay. But for longest time aloft I recommend using a balloon or a blimp ...

The statement "larger props are more aerodynamically efficient then smaller ones" is not generally true. I have read the paper of D. Rogers and therefore don't like it. The reasons are that with a excessively large prop you get too much drag towards the prop tip and you get too much wetted area. Optimizing props is not quite as simple as optimizing glider wings by increasing span and aspect ratio.

It is simple to build an airplane with a huge prop diameter, e.g. same as its wing span. Why does nobody do it, not even record planes, niether in models nor in full scale? Because its not efficient! The rules of thumb noted above (pitch ratio, pitch speed, power ratio) work better.

Prop development is still ongoing. See for example the developments of LeoMotion. I am interested in how things go on!


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