If you build it right, that means you get the right weight, a 1404 motors with KV around 3800-3900 is more than enough. The motors have never been even warmed up with my high PIDs. For an orderly cruise flight, only a current of around 3.5A is enough for all motors!!!! Peaks are up to 30A if you can handle it. Bigger motors are just heavier and I do not think it is the benefit needed. It is about 8 g plus on motors in this case, that is about 9% of the dry quad weight.

I don't mean to say that the T-motors are bad, on the contrary, they are great, but they are useless for a light 3.5 inch. If you're closer to 220g with the battery, I'd definitely use them, if you're more like 160g, I'd stick with the 1404.

I don't have much time for Scythe at the moment and I'm still waiting for components, so it's not moving much. But today I made an integrated antenna to be lightweight yet suitable for LR use.

The regular LHCP antennas are really heavy, put it on a scale and you'll see... The new antennas for Vista are definitely the lightest, but they have the disadvantage of being short, so they will be shielded by the action camera when quad returning. Their radiation characteristics are not very good, but here the weight is simply a crucial thing and I don't expect to fly more than 3 km far with such a small quad, but we will see. The antenna needs to be extended, the cable has sufficient reserve.

At the same time, the ELRS control link antenna that I am using now (tower antenna) is insufficient for LR. The antenna is actually sufficient, but the problem is with its shielding by the body of the quad, it is not possible to simply stick it out of the quad. And even a standard ELRS T-antenna (dipole) cannot be attached well to such a small quad so that the body does not shade the antenna. So I took a standard frsky monopole antenna and integrated it together with a LHCP antenna for the video link. Although the monopole antenna has a slightly lower sensitivity, the fact that it will never be shielded and always in vertical polarization during normal flight leads to significantly better results.

All you need is a pair of shrink tubing of a suitable diameter, a piece of guide tube for an old school frsky antenna and handy hands. The guide tube has an outer diameter of 3 mm, the same as the tubing on the LHCP antenna.

I started by cutting the guide tube to the required length. Then it is cut lengthwise so that a longitudinal gap of about 1 mm wide is created in it, which is the most demanding action of the entire creation. I did it with a TIGER razor. The result is on the first photo. The whole idea can be seen in the second photo, the cable of the 5.8 GHz antenna is passed through the guide tube and then the gray 2.4 GHz antenna is inserted into the gap of the guide tube. At the end of the gap, the antenna bends to the side.

So, first of all, a guide tube is connected to one shrink tube, which is in the third photo.

Then the active end of the 2.4 GHz antenna is put into the shrink tube to make it more durable and at the same time to strengthen it. The active part of the antenna is shortened to 28 mm if the active end of the antenna is shrunk into a shrink tube, if not shrunk, the length should be 28.5 to 29 mm to tune to the center of the band. Then the antenna is inserted into the gap, which can be seen in the first photo. Finally, the whole thing is shrunk again with an overlap into another shrink tube. The end of the antenna used to hold it is once again shrunk with a shrink tube to a total diameter of 4 mm, so that it is possible to put the antenna in a holder with a standard hole diameter. This can be seen in the second photo. The last photo shows the integrated antenna on the frame.

(23-Nov-2022, 05:14 PM)MomoBrut Wrote: I'm starting to build the second piece of Scythe, this time the LR version. I haven't quite started yet, I'm rather thinking about how to make it work. I don't want to change motors, I want to use motors with the same KV, I would like to get to a cruise flight time of over 15-20 minutes and a total distance of at least 15-20 km, to have safe reserve for 10-15 min flight times when some wind occurs, which corresponds to an average speed of something like 60 km/h. I want to use only 3s HV batterie, e.g. 1550 mAh, which weighs 100 g and is still fine in terms of size. All in all, including the Naked Hero 8 and the GPS module, I should have a sufficient reserve of up to 250g. I will use the Polar Nano camera so that it can be flown in poor lighting conditions. I haven't calculated it yet, but based on my experience it might be even bolder.

My 7 inch LR flies for over 23 minutes at an average speed of over 80 km/h, flies a little over 26 km and weighs almost 1.7 kg. So the Scythe LR will be a completely different animal.

I am concerned about the reliability of Naked Vista. So far I haven't had a problem with it, I have about 3 hours of flying time. So I'd appreciate information on your experience with Naked Vista reliability. And have you ever try the 3s battery for your motors (with about the same KV as I remember)? 3850 KV motors should be very efficient at 3s. The Scythe is bloodily overpowered with lightweight 4s.

If you want the 'best' range, you could try the new HQProp bi-blades. Putting them on 3s would be a bit more efficient (kind of like putting a 6s motor on 4s for long range), but would nerf the top end considerably. That'd be one way to do it without changing out hardware.

(08-Dec-2022, 06:01 PM)Rob3ddd Wrote: I’m in the process of getting parts for a light weight 3.5” but can’t make up my mind on motors.
  The 1404 are giving you plenty of power and acceleration without pulling your battery down?

   I am tempted to try t-motor P1604 3800Kv but it’s still fairly new and not much reviews or testing.

I plan to get my hands on the P1604 to test at some point as I am curious myself. Look at the F1404 vs F1408 testing I did to get an idea of what you might see with the P1604, but maybe cut the difference in half.

My guess would be that we'd get more top end, but require a bigger battery to drive it with the downside of less efficient lower throttle, and require more throttle for the same speed given the extra weight of the battery/motors. You'd get extra inertia as well. That said, I could prove myself wrong in testing (which wouldn't be the first time).

I can say that the F1404 do not feel like they are lacking top end, and I rarely touch it in regular flight/racing etc, and I'm not holding back usually. Would be interesting to try a 1404 build next to a 1604 build with a naked gopro on it.

You probably mean HQprop T3.5x2.2x2, I looked at them too. Double-blades always behave much worse than tri-blades. Basically, they are only effective for cruising, anything else is already a compromise. That's why I don't admire them. If the flight time ends up being shorter than I expect, I'll try them. The final decision will be made when it flies. But it will take some time, it's -9 degrees Celsius here and flying is the last thing that wouldn't come to mind.

The end of the year was quite demanding, I can't keep up. Plus I still don't have all the components. I ordered the Flywoo (Goku) GM10 Nano V3 GPS module (weighs 2.2 g), which is equipped with the latest generation M10050 chip. I'll see how it works.

For now, I stripped another Vista, conformally coated it and put it under the top plate along with the HM EP1 receiver. The EP1 fits behind the camera, I made the antenna with the understanding that a longer cable would be needed. There isn't much room left. All that is missing is to attach the GPS module to the top plate.

(19-Dec-2022, 10:33 PM)MomoBrut Wrote: You probably mean HQprop T3.5x2.2x2, I looked at them too. Double-blades always behave much worse than tri-blades. Basically, they are only effective for cruising, anything else is already a compromise. That's why I don't admire them. If the flight time ends up being shorter than I expect, I'll try them. The final decision will be made when it flies. But it will take some time, it's -9 degrees Celsius here and flying is the last thing that wouldn't come to mind.

Well, you're not wrong

Nice video. I have tried this on my 7 inch LR drone. Two-blades provide greater speed with less current to the motors. They are more efficient in cruising for longer distances at stable speeds. If the optimal lower propeller rpm is also observed, the two-blade is quieter, it sings at a lower frequency. Everything else is worse, and by quite a bit.

Well, today I received a lot of parcels. First, I received new GPS modules from Flywoo. I ordered the Goku GM10 v3 versions and specifically the Nano and Mini version. Functionally, they are completely identical, they differ only in size and weight. There is certainly not as much difference in reception sensitivity between the Mini and Nano versions as there is in weight. The Nano version is sufficiently sensitive and weighs only 2.2 g. The modules have flash memory and are fully configurable in Ublox u-center, it is possible to activate GNSS systems as needed. GPS, Beidou, Galileo are set from the factory. I switched to GPS, Glonnas and Galileo and now it works perfectly fine. The module enables the simultaneous function of 3 GNSS systems and the SBAS system, it can simultaneously communicate with up to 49 satellites.

This is a no brainer choice for a 10th generation UBLOX GPS module, it's cheap and works great, I recommend it.

So I tested the Nano version, it works great, it finds and locks normally more than 15 satellites even in foggy weather, and it will go to the top of Scythe. It only has a 12x16 mm footprint, it's really small.

Then arrived the battery for the Scythe LR, specifically the GNB 3s1550 HV. The battery weighs 94 g, so all up weight with the Hero8 naked camera, with larger antennas and GPS should be under 230 g, so there should still be a decent reserve up to 250 g.

And finally all the GEPRC GR1404 3850 kv motors arrived.

I attached the GPS module before making the marriage between the top and bottom plate of the frame. First I put the module in the shrink tube. I cut a spacer profile from a self-adhesive rubber foot from 3M to get the right angle for the GPS module. I glued the spacer profile with the self-adhesive side to the top plate, I glued the other side with contact glue (Uhu por) to the GPS module, it holds perfectly and can be carefully removed.

Next, I set the LED strip pin to the GoPro control signal as USER2 mode. It is thus possible to activate and deactivate the recording during the flight. And I soldered the cable with the correct connector to the camera.

And finally I connected the wires of the upper and lower plate of the frame together, so I completed the marriage. The GPS module is connected to UART2 and is powered from the same pin as Rx, so it is always possible to activate both Rx and the GPS module from USB before connecting the main battery. So the GPS fix can be done with USB power, I use a smartphone with the SpeedeBee app running, so I can immediately see how many satellites I have including my current location. Very handy solution ... At the same time it is possible to check everything via Tx telemetry without draining the main battery and overheating Vista.

So I flew the first three batteries. I calibrated the current sensor. So if I fly for 1200 mAh at drop to 3.5V per cell, I can last 18 minutes in flight. Well, it's exactly as I assumed, tested with HQ T3.5x2.5x3 propellers.
It flies like a bit of a nimble cruiser on the 3s, it's very stable and still maneuverable enough. I'm satisfied. The quad is really quiet at cruising speed. A comfortable and efficient level cruising speed is between 50 and 60 km/h at a current of 4 to 4.5 A.

The quad alone with all the extra gimmicks weighs 103 g and the takeoff weight with the Naked Hero8 and GNB 3s1550 Hv battery is 224 g.

And two Scythes side by side. Two completely different quads in behavior, but they are built on the same components, so there is no problem with servicing, no need to buy different spare motors or propellers or the frame itself, that's how I like it ...

That is some very nice, clean building.

I usually have wires going all over the place.