(20-May-2024, 10:51 PM)iFly4rotors Wrote: Hi Pathfinder,

Now, I am confused. The SmartAudio or Tramp is just a method to change
the VTX settings, so how is that effecting the signal?

What is FSEL ?

Later, iFly  

I messed up it's Op Model that you change to Free and FSEL to Chan.  It's listed in the Betaflight Smartaudio docs.

https://betaflight.com/docs/wiki/guides/...g-sub-menu

It was suggested in that video i posted for Seismic.

(19-May-2024, 10:15 PM)SeismicCWave Wrote: So the real test will be to actually fly this setup but I need to find some motors. 1303's are pretty boring since I already have those on two more AOS T3 frames. Time to try something else. Any suggestions? 1204s?

1204 is a good size and powerful, but not too much.  1404 is probably too fast for your flight area and anything bigger is definitely way to fast.

(20-May-2024, 11:43 PM)Pathfinder075 Wrote: 1204 is a good size and powerful, but not too much.  1404 is probably too fast for your flight area and anything bigger is definitely way to fast.

Interestingly the 1303's are the lightest. So boring it is. I bought more 1303's.

Keep in mind that smaller props need more RPM to generate thrust 
than larger props and need higher KV motors. KV * Voltage = RPM.
(no load condition and nominal battery voltage use for comparison).

Consequently, a 1204 8000Kv motor on 2S spins at 59,200 RPM,
while a 1404 3950Kv motor on 2S spins at 29,230 RPM. This is
why using larger motors often has no advantage over smaller
motors. Interestingly, as the motor size gets bigger, the KV goes
down. Of course, this is because higher voltage (larger cell count)
batteries are used. 

Plus, larger motors are heavier than smaller motors which just
adds unnecessary weight to a 2-inch (well, really any size) quad.
With larger prop sizes, the motor weight is less of a factor than
with the smaller quads.

This is why you might see someone put big motors on a small
quad and then wonder why it doesn't fly as good as with the
smaller motors.

On a 2S craft, you could push the KV up to 10,000 or more and
get better performance than from a motor with lower KV even
though it might be physically smaller than other motors.

Later, iFly 

(21-May-2024, 02:19 AM)SeismicCWave Wrote: Interestingly the 1303's are the lightest. So boring it is. I bought more 1303's.

Curious, which 1303s are you using? kv? Think iFly is on to something kv-wise...

FWIW, I use a "saved page to desktop" version of this to get me in the ballpark at the outset:

WarpDriveProps.com Propeller Tip Speed Calculator
https://warpdriveprops.com/propspd2.html

Example, say you’re using FPVCycle 13mm motors @ 6350kv, on 2S:

6,350kv x 8v = 50,800 rpm
Then, on the warpdrive calc:

3” Prop Diameter
50,800 RPM

yields:
453 = Prop Tip Speed in Mph. (Seems the flying dentist dialed in those motors for most efficient on 2S huh)
767 = The Speed of sound in Mph. Calculated using outside temp.
0.590612777053455 = Prop Tip Speed in Mach. Maximum performance between 0.8-0.92 Mach.

OK, what if you up 2S to 3S then?:

6,350kv x 12v = 76,200 rpm

yields:
680 = Prop Tip Speed in Mph.
767 = The Speed of sound in Mph. Calculated using outside temp.
0.8865710560625815 = Prop Tip Speed in Mach. Maximum performance between 0.8-0.92 Mach.

Kinda fun to dink around ahead of time for me anyways...

I am using these 1303. The manufacturer is claiming 5.6 grams which is lighter than some 1204 at 6.1 grams.

At this point I don't really bother with calculating kV. I used to be pretty anal and put a disk on a motor and used an optical tach to measure kV. Now I just buy and fly.

No worries... swish\ \ \ | | |...this was not the info you were looking for...| | | / / /swish

(21-May-2024, 06:15 PM)skywanderer Wrote: No worries... swish\ \ \ | | |...this was not the info you were looking for...| | | / / /swish

No, that was great info. I just don't pay much attention to the numbers anymore. I plug things together. If they work great. If not I swap them out.

Nah, honestly I do look sometimes. I did some search and figured those 1303 motors can be powered with either a 2S or 3S pack. That's why I bought them. 

Then I am started to think maybe it is too light as a 2S machine. Maybe I need to power it with 3S. Unfortunately a 3S takes up a lot of space on the bottom of my AOS T3 frame. I just 3D printed some TPU battery holder for the 2S.

I know I am hijacking the heck out of this thread. The reason why I thought 2S is too light is because of the bobbling I noticed.


So I emailed Chris Rosser and asked him. Read between the lines he thinks my props are too big and heavy and the motors are too light.  I have some lighter props on order.

I love this kind of tinkering So no worries. Keep those numbers coming.

Regarding prop tip speed. I watched a video... will see if I can find it...
about prop tip speed. It was actually propeller physics about airplanes
and other aircraft propellers, but I think that the information applies to 
any craft with propellers.  It seems that 450 mph (I think) is the optimal 
tip speed for propellers. Increasing the speed beyond 450 mph does not 
increase the thrust. I don't know the physics behind it, just what the guy 
said. According to him, you don't gain anything by making the prop go 
faster.

If you run the numbers on any given motor's voltage (cell count) rating
and the KV of the motor, you get somewhere between 50,000 and 60,000
RPM for all motor sizes. I am guessing (but don't know for sure) that this 
puts the prop tip speed somewhere close to 450 mph for pretty much
all motors. 

I will see if I can find the video and link it in this thread. 

Later, iFly  

1204 motors actually have around 30% more stator volume than 1303 motors, so it is normal they will be heavier and handle props better. However most "1303" are actually 1303+ motors, if they are 1303.5, then they have pretty much the same stator volume as the 1204s. Theoretically the taller motors will be more responsive/efficient while having less low end torque, but with the 1mm size variance, probably not much difference and the motor quality (bearings, magnets) probably more important. Not sure which 1303 motors you actually have?

I have a set of T-motor F1204s 5000?kv that work really nicely on a 3" pick. Mostly fly 3S but will do 4S nicely too, though they are rated 2-3S. Relatively light, smooth, and efficient, great buy if you find them on sale.

(21-May-2024, 08:46 PM)SeismicCWave Wrote: snip
I love this kind of tinkering So no worries. Keep those numbers coming.

Thanks for the leeway, don't know exactly why but... I always seem to be crunching numbers.

fwiw, from my notes        :

Quote:------------------------------------------------------
1.6" Prop Diameter. In inches - (40mm)
95,000 * Engine Rpm. ( Max )
452 = Prop Tip Speed in Mph.
------------------------------------------------------
2" Prop Diameter. In inches.
76,000 * Engine Rpm. ( Max )
452 = Prop Tip Speed in Mph.
------------------------------------------------------
2.5" Prop Diameter. In inches.
60,500 * Engine Rpm. ( Max ) (55,440 rpm = 110%)
450 = Prop Tip Speed in Mph.
------------------------------------------------------
3" Prop Diameter. In inches.
50,400 * Engine Rpm. ( Max ) (55,440 rpm = 110%)
450 = Prop Tip Speed in Mph.
------------------------------------------------------
3.5" Prop Diameter. In inches.
43,200 * Engine Rpm. ( Max ) (47,520 rpm = 110%)
450 = Prop Tip Speed in Mph.
------------------------------------------------------
4" Prop Diameter Inches
38,000 * Engine Rpm. ( Max )
452 = Prop Tip Speed in Mph

-----------------------------------------------
5" Prop Diameter Inches
39,200 * Engine Rpm. ( Max )
583 = Prop Tip Speed in Mph

-----------------------------------------------
1S:
20,000kv x 4v = 80,000 rpm = 476mph prop tip speed (1S lipo)
10,000kv x 8v = 80,000 rpm = 476mph prop tip speed (2S lipo)
24,000kv x 4v = 96,000 rpm
21,000kv x 4v = 84,000 rpm
19,000kv x 4v = 76,000 rpm
18,000kv x 4v = 72,000 rpm
15,500kv x 4v = 62,000 rpm
14,000kv x 4v = 56,000 rpm
12,022kv x 4v = 48,088 rpm
11,500kv x 4v = 46,000 rpm
11,400kv x 4v = 45,600 rpm
10,000kv x 4v = 40,000 rpm
8,500kv  x 4v = 34,000 rpm
8,000kv  x 4v = 32,000 rpm
7,800kv  x 4v = 31,200 rpm
7,500kv  x 4v = 30,000 rpm
5,000kv  x 4v = 20,000 rpm
4,000kv  x 4v = 16,000 rpm

------------------------------------------------------
2S:
15,500kv x 8v = 124,000 rpm
14,000kv x 8v = 112,000 rpm
11,500kv x 8v = 92,000 rpm
11,400kv x 8v = 91,200 rpm
10,000kv x 8v = 80,000 rpm
9,600kv x 8v = 76,000 rpm
9,000kv x 8v = 72,000 rpm
8,500kv x 8v = 68,000 rpm (2.5 prop = 68,000rpms = 506mph prop tip speed)
8,000kv x 8v = 64,800 rpm (2.5 prop = 64,000rpms = 476mph prop tip speed)
7,500kv x 8v = 60,800 rpm (2.5 prop = 60,000rpms = 446mph prop tip speed)
7,000kv x 8v = 56,800 rpm
6,350kv x 8v = 50,800 rpm
6,250kv x 8v = 50,000 rpm
6,100kv x 8v = 48,800 rpm
6,000kv x 8v = 48,000 rpm
5,500kv x 8v = 44,000 rpm
5,000kv x 8v = 40,000 rpm
5,150kv x 8v = 41,200 rpm
5,000kv x 8v = 40,000 rpm
4,850kv x 8v = 38,800 rpm
4.500kv x 8v = 36,000 rpm
3,950kv x 8v = 31,600 rpm
3,900kv x 8v = 31,200 rpm
3,800kv x 8v = 30,400 rpm
3,750kv x 8v = 30,000 rpm
3,450kv x 8v = 27,600 rpm
3,150kv x 8v = 25,200 rpm
3,100kv x 8v = 24,800 rpm
2,650kv x 8v = 21,200 rpm
-----------------------------------------------
3S:
6,350kv x 12v = 76,200 rpm
6,000kv x 12v = 72,000 rpm
5,150kv x 12v = 61,800 rpm
5,100kv x 12v = 61,200 rpm
5,000kv x 12v = 60,000 rpm
4,850kv x 12v = 58,200 rpm
4.500kv x 12v = 54,000 rpm
4.200kv x 12v = 50,400 rpm
3,950kv x 12v = 47,400 rpm
3,900kv x 12v = 46,800 rpm
3,800kv x 12v = 45,600 rpm
3,750kv x 12v = 45,000 rpm
3,600kv x 12v = 43,200 rpm
3,450kv x 12v = 41,400 rpm
3,150kv x 12v = 37,800 rpm
3,100kv x 12v = 37,200 rpm
2,950kv x 12v = 35,400 rpm
2,650kv x 12v = 31,800 rpm
2,450kv x 12v = 29,400 rpm
2,100kv x 12v = 25,200 rpm
1,700kv x 12v = 20,400 rpm
-----------------------------------------------

...just some more stuff to chew on...

(21-May-2024, 09:17 PM)iFly4rotors Wrote: Regarding prop tip speed. I watched a video... will see if I can find it...
about prop tip speed. It was actually propeller physics about airplanes
and other aircraft propellers, but I think that the information applies to 
any craft with propellers.  It seems that 450 mph (I think) is the optimal 
tip speed for propellers. Increasing the speed beyond 450 mph does not 
increase the thrust. I don't know the physics behind it, just what the guy 
said. According to him, you don't gain anything by making the prop go 
faster.

If you run the numbers on any given motor's voltage (cell count) rating
and the KV of the motor, you get somewhere between 50,000 and 60,000
RPM for all motor sizes. I am guessing (but don't know for sure) that this 
puts the prop tip speed somewhere close to 450 mph for pretty much
all motors. 

I will see if I can find the video and link it in this thread. 

Later, iFly  

Funny enough, I think it was a utube vid about WW2 fighters/props that I heard the 450mph bit about. I think... can't remember for sure but that leads to notes for me to check out in my curious mode.

Anyway, that warpdrive props linky has text saying mostly that. For us, we can increase the kv for more pop/faster prop spinning/changing at the expense of battery/gas mileage. Closer to 450 mph for efficiency, faster for more performance goal.

And... pardon to OP for enabling further hijacking...     

(21-May-2024, 09:20 PM)mstc Wrote: 1204 motors actually have around 30% more stator volume than 1303 motors, so it is normal they will be heavier and handle props better. However most "1303" are actually 1303+ motors, if they are 1303.5, then they have pretty much the same stator volume as the 1204s. Theoretically the taller motors will be more responsive/efficient while having less low end torque, but with the 1mm size variance, probably not much difference and the motor quality (bearings, magnets) probably more important. Not sure which 1303 motors you actually have?

I have a set of T-motor F1204s 5000?kv that work really nicely on a 3" pick. Mostly fly 3S but will do 4S nicely too, though they are rated 2-3S. Relatively light, smooth, and efficient, great buy if you find them on sale.

Ima dork, admit it...  was curious to get some inkling of size differences in different motors, notes started and added on to:

Quote:motor listed by increasing stator cylindrical volume size (cubic mm):

0603:    (6/2)^2 x 3.14 x 3 =     85
0802:    (8/2)^2 x 3.14 x 2 =     100
0803:    (8/2)^2 x 3.14 x 3 =     151
1002:    (10/2)^2 x 3.14 x 2 =    157
1102:    (11/2)^2 x 3.14 x 2 =    190
0804:    (8/2)^2 x 3.14 x 4 =     201
1202     (12/2)^2 x 3.14 x 2 =    226
1003:    (10/2)^2 x 3.14 x 3 =    235
0805:    (8/2)^2 x 3.14 x 5 =     251
1302     (13/2)^2 x 3.14 x 2 =    265
1202.5   (12/2)^2 x 3.14 x 2.5 =  283
1103:    (11/2)^2 x 3.14 x 3 =    285
1202.6   (12/2)^2 x 3.14 x 2.6 =  294
1402:    (14/2)^2 x 3.14 x 2 =    308
0905:    (9/2)^2 x 3.14 x 5 =     318
1103.5:  (11/2)^2 x 3.14 x 3.5 =  332
1302.5:  (13/2)^2 x 3.14 x 2.5 =  332
1203     (12/2)^2 x 3.14 x 3 =    339
1104:    (11/2)^2 x 3.14 x 4 =    380
1303:    (13/2)^2 x 3.14 x 3 =    398
1303.25: (13/2)^2 x 3.14x3.25 =   431
1204:    (12/2)^2 x 3.14 x 4 =    452
1403:    (14/2)^2 x 3.14 x 3 =    462
1303.5:  (13/2)^2 x 3.14 x 3.5 =  464
1105:    (11/2)^2 x 3.14 x 5 =    475
1303.6:  (13/2)^2 x 3.14 x 3.6 =  478
1204.5:  (12/2)^2 x 3.14 x 4.5 =  509
1503:    (15/2)^2 x 3.14 x 3 =    530
1304:    (13/2)^2 x 3.14 x 4 =    531
1106:    (11/2)^2 x 3.14 x 6 =    570
1404:    (14/2)^2 x 3.14 x 4 =    615
1305:    (13/2)^2 x 3.14 x 5 =    663
1107:    (11/2)^2 x 3.14 x 7 =    665
1206:    (12/2)^2 x 3.14 x 6 =    678
1504:    (15/2)^2 x 3.14 x 4 =    706
1207:    (12/2)^2 x 3.14 x 7 =    791
1504.5:  (15/2)^2 x 3.14 x 4.5 =  795
1306:    (13/2)^2 x 3.14 x 6 =    796
1604:    (16/2)^2 x 3.14 x 4 =    804
1505:    (15/2)^2 x 3.14 x 5 =    883
1605:    (16/2)^2 x 3.14 x 5 =   1005
1804:    (18/2)^2 x 3.14 x 4 =   1017
1407:    (14/2)^2 x 3.14 x 7 =   1077
2203:    (22/2)^2 x 3.14 x 3 =   1140
1804.5:  (18/2)^2 x 3.14 x 4.5 = 1145
1408:    (14/2)^2 x 3.14 x 8 =   1231
1507:    (15/2)^2 x 3.14 x 7 =   1236
2004:    (20/2)^2 x 3.14 x 4 =   1256
1805:    (18/2)^2 x 3.14 x 5 =   1272
2203.5:  (22/2)^2 x 3.14 x 3.5 = 1330
2104:    (21/2)^2 x 3.14 x 4 =   1385
1607:    (16/2)^2 x 3.14 x 7 =   1407
2303.5:  (23/2)^2 x 3.14 x 3.5 = 1453
2204:    (22/2)^2 x 3.14 x 4 =   1520
1806:    (18/2)^2 x 3.14 x 6 =   1526

2006:    (20/2)^2 x 3.14 x 6 =   1884
2205:    (22/2)^2 x 3.14 x 5 =   1900
2205.5:  (22/2)^2 x 3.14 x 5.5 = 2090
2206:    (22/2)^2 x 3.14 x 6 =   2280
2306:    (23/2)^2 x 3.14 x 6 =   2492
2207:    (22/2)^2 x 3.14 x 7 =   2660
2308:    (23/2)^2 x 3.14 x 8 =   3312

I'm sure I missed a few, and a couple that don't exist are in the heap, whatever...

I know you can rout out pi as a common denominator for smaller numbers, but I like quasi 0-1000 thing.

(21-May-2024, 09:34 PM)skywanderer Wrote: Funny enough, I think it was a utube vid about WW2 fighters/props that I heard the 450mph bit about. I think... can't remember for sure but that leads to notes for me to check out in my curious mode.

Anyway, that warpdrive props linky has text saying mostly that. For us, we can increase the kv for more pop/faster prop spinning/changing at the expense of battery/gas mileage. Closer to 450 mph for efficiency, faster for more performance goal.

And... pardon to OP for enabling further hijacking...     

I did try to calculate prop tips speed a bit years ago. Mainly I wanted to know the rotor tip speed of single main rotor helicopter. Not such much about 450 mph the engineers were trying hard not to break the sound barrier on those rotors. So an Aerospatiale Lama spun the main rotor at 351 RPM. The reason was to keep the tip speed believe the speed of sound with the rotor span in question. 

The little Hughes 500 went to more blades so they can keep a shorter span and maintain the same RPM before the tips start to break the sound barrier. 

I believe the Huey UH1 did break the sound barrier once in a while to create that slapping noise.

Apparently not very efficient once they break the sound barrier because of the turbulence created.

Now we are way out of topic.......

(21-May-2024, 09:20 PM)mstc Wrote: 1204 motors actually have around 30% more stator volume than 1303 motors, so it is normal they will be heavier and handle props better. However most "1303" are actually 1303+ motors, if they are 1303.5, then they have pretty much the same stator volume as the 1204s. Theoretically the taller motors will be more responsive/efficient while having less low end torque, but with the 1mm size variance, probably not much difference and the motor quality (bearings, magnets) probably more important. Not sure which 1303 motors you actually have?

I have a set of T-motor F1204s 5000?kv that work really nicely on a 3" pick. Mostly fly 3S but will do 4S nicely too, though they are rated 2-3S. Relatively light, smooth, and efficient, great buy if you find them on sale.

Yes I have been looking at those. I may have to collect a set just to try.

Ok let me edit this post instead of creating another post to clutter up this thread.

So kV or not kV, that is the question.

I posted the wobbly flying of this analog 3" Toothpick. Chris Rosser thinks the prop I am using is too heavy for a light quad.

So I figure maybe instead of trying to save weight and count grams what if I go all out and add some weight.

So I did change the props. I thought I was using some HQ T3X3X3 but I was actually using a set of Gemfan Wind dancer I picked up from Amazon. Big and clunky prop. So I tested a few different props and decided to use a set of "real T3X3X3 since I have a whole bunch of them.

Then a 3D printed canopy came in the mail and I can install a 19mm camera instead of having to use the Nano cameras. This is to add weight.

So the Foxeer T Rex looked big and clunky and heavy so on it goes.

I went from 67.5 grams to 74 grams by the time I finished. All that work just to gain 6.5 grams. 

Well I test flew it and although it was pretty calm the quad did seem to fly much smoother. 

So here is a picture. The camera is out of the quad for some KoteKing water proofing.