(04-Jan-2021, 06:43 PM)V-22 Wrote: I think 4" will definitely be easier than 3". What is the lightest weight 4" frame we can use as a base?

I'll run some numbers and see if we can do it on 2s!

Hi V-22,

Download my Parts Guide and check out the comparisons on the 4 inch Frames tab. There a couple of lightweight frame choices. FPV Cycle {KababFPV} frames are some of the lightest, but these are pretty skimpy frames. The best bet might be to choose a very light frame, use the base and a custom fabricated light weight top plate. Another option is the use a set of light weight arms with custom fabricated light weight main frame plates. The hardware is another factor. The nylon standoff columns are actually lighter than the aluminum ones. 

Also, the 1404 motors are about as large as you can go, 
but the 1303's seem to be a little short on the power side; 
more testing needs to be done.
Yeah, run some eCalc on these combinations.

Here is what I came up with, assuming a 125g dry weight and a 2s VTC6 18650 3000mAh pack discharged ~95%. AUW is 218g. Feasible?

Lumenier RX1306-9  3100kv, 4024 prop, 2.2 thrust to weight ratio, 10246 m range, 23.3 min flight time (41.6 min hover!)
   

Lumenier RX1306-9  3100kv, 4030 prop, 2.4 thrust to weight ratio, 11274 m range (7 miles!), 22.1 min flight time (41.6 min hover!)
   

RCinPower QAV 1104 4000kv or T1104 4000kv, 4030 prop, 3.1 thrust to weight ratio, 10583 m range, 18.5 min flight time
       

Lumenier RX1306-7  4000kv, 4030 prop, 3.3 thrust to weight ratio, 11119 m range, 18.7 min flight time
   

Lumenier RX1306-7  4000kv, 4024 prop, 3.1 thrust to weight ratio, 10147 m range, 19.6 min flight time
   

I think the Lumenier 1306 4000kv would actually be the best option, as you have a little more power on tap. Unfortunately I can't find any of these motors available to buy, but at least it gives us a sense as to where to look. Any thoughts for similar motors?

https://www.ecalc.ch/xcoptercalc.php?eca...ng%20Range

(04-Jan-2021, 07:02 PM)iFly4rotors Wrote: Also, the 1404 motors are about as large as you can go, 
but the 1303's seem to be a little short on the power side; 
more testing needs to be done.
Yeah, run some eCalc on these combinations.

I think you're dead on here. 1306 looks pretty nice if you can find efficiently built motors, and maybe even something as small as a 1104 would work. Would a 1205 be ideal? Hopefully this is an active area of research with the motor manufacturers who see the sub250g writing on the wall!

Yeah, 1306 might work or, maybe, a 1402 ?? For endurance, you don't need top end or gut wrenching performance; just torque and easy pulling.

Just saw that Lumenier has a new 1205 motor, only available in 5500kv or 7000kv though. Might be too high for this purpose.
https://www.getfpv.com/lumenier-freybott...000kv.html

Hi V-22,

Here is what I know from my Phantom-X which has been running 1303 5000kv FPV Cycle motors for some time now, 
it will pull 4 inch props with a 2s 3000 mAh 18650  pack strapped on { 226 grams AUW } and fly for more than 21 minutes. 

This 21 minute time is the BEST that I have achieved 
with any quad having an All Up Weight less than 250 grams.

For me, this would be the configuration to beat. 

Since I didn't have a GPS unit installed, I would not try any distance flights.
Currently, it is down for upgrades; new FC and VTX, plus adding a GPS unit.

The Phantom-X was my first build which I use as an experimental platform. 
It is built on a GEPRC Phantom frame with overlay arm extensions set to accommodate 4 inch props.

Think that I will start a new build thread for this endeavor.  

(06-Jan-2021, 06:59 AM)V-22 Wrote: Just saw that Lumenier has a new 1205 motor, only available in 5500kv or 7000kv though. Might be too high for this purpose.
https://www.getfpv.com/lumenier-freybott...000kv.html

Hi V-22,

Good find. I will be ordering a set of these in 7000kv.
These should be good motors to use with the Diatone Taycan25 ducts in a light weight frame. 
Since the ducts didn't work so well on FrankenFly, I will do a new build with some new ideas for the Ducted Pusher.

Currently:

Builds that are In Progress:

1) DIY Gen 3 915 mHz antenna 
2) Katarms-LR7x
3) BEAST

Next proposed builds:

4) 85mm Tiny Whoop  {no thread yet}  <<  This one is for me to fly in the house.
5) 30 minute long range; 4 or 5 inch.  {no thread yet}
6) 2.5 inch Taycan25 ducted pusher.   {no thread yet}

2021-01-12

For now, I have abandoned the DIY Gen 3 antenna build. So, moving on...

The 7 inch builds are on hold until I can find a place to fly them. I can no longer fly at the soccer field where I had planned to test them; the other park is just too small for a 7 inch; it would just be like a hover test with no where to go. I will work on them when there is not much else to do.

Since I don't have all the parts for another Taycan25 duct build, it will have to wait. I will see about getting the additional parts that I need for this build, but for now...

The 85mm Tiny Whoop, Tiny-Black-85, is complete and the initial test flights were successful.

The 30 minute long range, Quest250-LR, is in process. I have most of the parts so I will be actively working on this one.

The first post of the Quest250-LR thread includes a list of other builds that have the same criteria: 
Sub 250 gram AUW, 30 minute Fly Time, 10K distance. No size limits, but most likely will be 3 inch or 4 inch. 

The post also includes similar Long Range builds even though they may not have been built with the listed criteria in mind.

Stay tuned ... 

While waiting on parts for the Quest250-LR build, I have disassembled the Phantom-X for some upgrades and set it up for Long Range.      Interestingly, this craft has gotten some of the best Fly Time performance metrics of any of my builds.

On the subject of using Arm Extensions to run larger props on a smaller frame. 

Even though the method will work, it is certainly not the norm, the use of arm extensions does allow trying larger props without a complete rebuild. Assuming that there is some extra slack in the motor wiring, it is pretty easy to unbolt the motors, add the extension, then bolt the motors in the new location.  

Using arm overlays is also an interesting method of repairing a damaged frame; sometimes. Again, this is not the norm, it does add weight, and may not be viable in all situations. Furthermore, there are a variety of arms available and some are more suited to this purpose than others. Also, there is a cost in buying the arms. 

Two of my builds use arm extensions to allow using larger props on frames designed for smaller ones. With my very first build, the Phantom-X, I had a GEPRC Phantom frame and some Micro Allen 3 inch arms, but no 4 inch frame, so I decided just to use what I had. In fact, I thought this might be temporary unit I could get a 4 inch frame. After all, this quad was intended to be used for experimental purposes. As it turns out, I am still flying it with this frame configuration. 

The Micro Alien arms were not wide enough to mount with all 4 holes, so I just used 2 bolts  per arm to attach them to the Phantom frame at the motor mount locations. At this point, except for drilling holes, I did not otherwise alter the arms. Detail of arm attachment. Picture of frame with arm extensions. At the time there was a lot of curiosity about stress on the original frame, however, time has proven the method viable. I have a lot of flights, and crashes, on this craft and it is still holding up. However, I am an easy cruiser; I don't race or fly acro.  

Since I am upgrading the Phantom-X, I have modified, shortened, the Micro Alien Arm Extensions. Here is a detailed picture.

As a result of crashing my Phantom-3A into a metal light pole, the GEPRC Phantom frame was bent enough to splinter one of the arms close to the main section of the frame. I salvaged this frame by overlaying  the arms with a set of rear TomoQuads Mosquito arms that I had in the parts bin. These particular arms were just right. One of the holes in the arm matched a hole in the Phantom frame and they were wide enough for 4 motor mount attachment bolts if needed. This  complete overlay method both supported the damaged arm and was long enough to run 4 inch props. View from Top,  View from Bottom. The repaired frame was then use in the Phantom-4X build. So far, so good. No issues at this point and the craft flies quite well. I am pleased with the results. 

Now, if you have the material, the tools, and the skills; small arm extensions can be fabricated from a variety of materials including, but not limited to, the following: carbon fiber sheets, Lexan, plexiglass, metal such as aluminum, or just about any sturdy plastic {you might be surprised what you can find and use}. 

In conclusion, Arm Extensions DO work and have their place; whether or not they are appropriate depends entirely on the builder, the reason, what is to be gained, costs, and effort. It is just another option.

Well, a new situation has come to light: 

The Low Voltage Cutoff setting and using Li-Ion, 18650, cells. 

Simply put, Most of the ESCs especially in the smaller boards have a Low Voltage Cutoff set at 3.5 volts which basically cuts the power at that voltage in order to protect LiPo batteries. Drone Drops out of the Sky. Now, the Li-Ion batteries can be discharged down to about 2.5 volts and still fly, but only without the Low Voltage Cutoff. 

The LVC can be turned off in BLHeli_32, but not in BLHeli_S.

 
See My Post #58  in [Build] 3" 250g 10km DJI Digital Build   <<  The discussions begin at Post #50 

I have also started a thread in the Long Range section:

[Tip & Trick]  Li-Ion 18650 Batteries and Low Voltage Cutoff  >  Last Post

Now, it seems that the Low Voltage Cutoff situation has taken another turn.

Further investigation suggests that there is NO Low Voltage Cutoff in BLHeli_S.
It seems that the LVC is implemented in the hardware and how the manufacturer builds the boards.

Now, it becomes a "crap shoot". Nothing for certain without testing individual boards.

On the positive side, it doesn't mean that LVC is implemented just because the ESC firmware is BLHeli_S.
BLHeli_32 just provides a method to turn it off LVC if it has been implemented. At least, this is my interpretation. 

Reference Quest250-LR post # 43

Reference 3" 250g 10km DJI Digital Build

Ok, now let's get back on track.

I have a brand new  Flywoo GNF4 35A 16x16 stack V2.1  that I will use it in the Phantom-X upgrade and test it. 

On the other hand, I think that I will buy a new FC board that has BLHeli_32 for the Quest250-LR build.

Well, I have ordered two whoop format AIO FCs with enough UARTS for the GPS and BLHeli_32:

CL RACING F7 WHOOP AIO V2

BETAFPV TOOTHPICK F405 2-4S AIO BRUSHLESS FLIGHT CONTROLLER 20A (BLHELI_32) V4

Yeah, I know, the second one is a BetaFPV product, but I am going to try it anyway.  

I really wanted to get one of the Flywoo FCs, but they seem to be out of stock. 

I might have been able to get one directly from Flywoo, 
but I didn't want to wait that long, so I am going to try these. 

While waiting on parts to arrive, I have been taking stock of my parts bin and thinking about my direction in this FPV journey. It seems that I have plenty of ALL components except perhaps motors which I may need something different than what I already have. I think that I could build about 6 or more quads without actually buying anything. 

For now, I want to finish the current outstanding builds and upgrades.

I am re-assembling the Phantom-X and building the Quest250-LR almost simultaneously since they are actually very similar quads and will be really close when completed.

I want to finish the two 7 inch builds; the Kararms-LR7x and the BEAST. Given the shear weight of the motors, I believe both of these will be over 250 grams and likely my only builds in this weight category.

After finishing these 4 builds, my primary focus will be getting in some Fly Time, searching for a good location to fly longer distances, and getting my 5K badge.

Stay tuned...