RedCruiser – DIY Depron airplane for FPV

Few months ago I’ve wrote about my first handmade Depron airplane. It was cool design. Super simple, with KFm-2 airfoil, durable and easy to fly. But it had few serious flaws:

  • motor mounted in front of fuselage is great for flight characteristics, but propellers breaks all the time. Even with prop savers,
  • big fuselage is not the same as fuselage with a lot of space inside.

Depron KFm-2 airplane with pusher propeller

That’s why, I have build a second Depron airplane. This time with pusher propeller mounted on a tower behind wing. Wing is almost the same design as in my first airplane. It is still an KFm-2 (Kline-Folgeman, modified) airfoil, 150mm chord, 12mm thick. But is a little shorter: 1200mm instead of 1250mm. The main difference is inside wing. Instead of carbon fiber spars I’ve used two carbon fiber 6mm pipes. That gives plenty of stiffness. Wing almost does not bend in flight, even during hard maneuvers. And generates more than enough lift to give nice, slow flying experience without danger of heavy stall. You really have to want to stall it. And event when it stalls, it recovers nicely: drops a nose, dives for a second or two, and you have lift again. No need to work with rudder, just let it dive and gain speed and then level.  Continue reading “RedCruiser – DIY Depron airplane for FPV” »

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Quick Review: FPV 1/4 CMOS HD Color Camera Module 600TVL 120 Degree Wide Angle

Usually I have absolutely nothing against buying cheap stuff from China. OK, maybe quality will not always be as expected, but usually it’s not worth paying extra 100% in price for 10% of extra quality. Usually, with some exceptions. Exception number one are mechanical parts like motors. Exception number two are FPV cameras. And the second one is new one. I’ve put it in place after using FPV 1/4 CMOS HD Color Camera Module 600TVL 120 Degree Wide Angle from Banggood for one month.

FPV 1/4 CMOS HD Color Camera Module 600TVL 120 Degree Wide Angle from Banggood Continue reading “Quick Review: FPV 1/4 CMOS HD Color Camera Module 600TVL 120 Degree Wide Angle” »

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5.8GHz FPV channel frequency table

For 5.8GHz FPV systems, there are 4 main bands divided into 8 channels each. That gives 32 channels free to use. So, in theory, 32 pilots should be able to fly FPV at the same time. Unfortunately, this is not true.

First of all, there are transmitters, and there are transmitters. Better, properly tuned, will broadcast in narrow frequency range. Cheaper, or just not properly tuned, will broadcast on much wider frequency range. The same goes for receivers. They can listen “only” to their frequency, but also to others. The result is, that a transmitter can pollute other channels. This is why, general rule is then 2 pilots should not fly on adjacent channels. If pilot A is using CH1, pilot B should use CH3 and so on.

Channel frequency for band (MHz)
Channel A (FR1) B (FR2) E (FR3) F (FR4)
1 5865 5733 5705 5740
2 5845 5752 5685 5760
3 5825 5771 5665 5780
4 5805 5790 5645 5800
5 5785 5809 5885 5820
6 5765 5828 5905 5840
7 5745 5847 5925 5860
8 5725 5866 5945 5880

Second of all, frequencies assigned to channels can overlap with channels in different bands. Just look at the chart below.

5.GHz FPV channel frequencies

Not only frequency separation between bands B and F is smaller than expected, there might me overlaps, channel 4 is crowded and band E jumps high and low. Nightmare that concludes: you should not fly CH4 on bands A and F. Also better not to use CH4 in band B. Just to be on safe side. On the other hand, band E (FR3) is not overlapping with other bands. Also band A is quite safe as long as you are not using CH4.

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Let’s build 250 class quadcopter: mostly done

It’s been few weeks since my last post about 250 class quadcopter based on carbon fiber ZMR250 frame. Machine is mostly finished by now. At least in LOS configuration. FPV gear has only arrived last week and I still had no time to put it in.

ZMR250 quadcopter

Anyway, it flies and crashes a lot. But this is 250. It’s supposed to do so. After little more than 2 hours in air I can say that:

  1. It is heavy. With 1.3Ah 3S LiPo battery and RunCam HD it weights 530g. Have to make it lighter…
  2. Turnigy Multistar V2 2206 2150KV “Baby Beast” with Gemfan 5030 propellers does not provide enough thrust. Do not get me wrong, it is fast, but I was kind of hoping for higher level craziness.
  3. It is tough. Oh the crashes it has survived…

ZMR250 with RunCam HD

ZMR250 in air

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