(24-Nov-2022, 12:23 AM)iFly4rotors Wrote: Hi fpvapnea,

Somehow, I missed this when reading this thread, but now I notice that you are using 
2 different size props on this bird; larger ones in the rear. That is an interesting concept. 
How did you come to try this. Evidently, it works really well. What are the differences
between 4 of the same and 2 different size ??

Yes, now you have my attention, yet again. Do tell.

Well it was not my original plan, but during the changeover to the new unplanned heavier AIO plus external baro and adding more grams while building , the end result with 4x40mmx4blades flew fine but at a very high throttle on 2s and crazy loud but still high on 3s. So not much left to bail out of scary situation etc.
Then you are out of options other them reduce weigh again (which i did not feel like) , or moving up in prop sizes. 
But when i move up to 2 inch i have an issue with clearance to the fpv camera on the front.
The tips would just hit.
I thought of you (as you used this in your baby naz build experiment) of maybe using spacers to lower the props just so slightly, but then the idea of mixed props popped in my head.(as i had no spacers but megatons of props). Did some youtube official scientific research if this was possible and found it to be no porblem based on an insane quad with 4 different props that Nurk put together, so went for it.
I immediately noticed the lower hover throttle so it worked.
Only thing left was to experiment with all possible combinations to find the best for this specific quad when fully loaded.
I dont notice any differences in flight behavior al all. Is just a matter of power.
Only when i go up to 6 blades on the rear i feel it is even more stable, but i drop flight time so the more efficient 2 blades huricanes won the battle of the props.  On the front 2 blades was too little and craaaaaazy loud and 3 blades was louder than 4 but without much power diff so stuck with 4 blades in front.

Hi fpvapnea,

Thanks. Sounds like something that I could try. Besides this build, I have another 
application where this will work that I want  to try it on. That would be a 2.5 inch 
GEPRC Phantom frame which will handle 3 inch props in the rear as it only has a 
single central standoff column in that location. My Phantom-3A build was fitted
with 3 inch props. I removed the two front columns and replaced with a single
central column, custom top plate, and adapter plate on the bottom. This was one
ugly craft, but flew quite well. 



Yes, I have built some pretty unconventional quads; crazy, right ?

Yep try it and let me know how it works. Amazing how these flight controllers just compensate for just about everything from different motors to different props. The thing is you have to think about it in your toolbox as easy to forget as a viable option in certain edga cases

Interesting find today.
As i was playing with my 2s 750mah HV flywoo and my 3s 850mah Dinogy Ultra Graphene 2.0, i noticed that the 2s was with its 33g exactly half the weight of the 3s.
So i was thinking , maybe i can squeeze more flight time out if the same weight by using 2 x 2s in parallel. So quickly soldered up a xt30 parallel adapter and it worked. Got to a comfortable 8:45 mins flight time compared to 7min for the same weight 3s.
The 3s has more power reserve , but for smooth filming that is not so needed . And if it is i can always use the 3s.  Found and ordered some 3s GNB's that are lighter but will arrive already on jan 27th next year ...... ffffffffffff  
Its impossible to get GNB's in europe faster than 2+ months. Still waiting for earlier orders i made more than 2 months back. Total crap.
Flywoo ships fast so wil just order a bunch of extra of these nice 2s lipos and go for the parallel trick. Black friday so cheaper as well.
   

If you weren't going to get stung on import charges, i would say try hobbyrc for the GNB batteries. They always have a good selection. But importing to Europe is bound to hurt the wallet more than ordering from China.

Yeah no thanks, thats going to absolutely hurt. Been there done that. EU import regulations have tightened up a lot recently. I will be patient ;-)

Ok, now we enter the battery discussion. Since one of my primary goals is,
and always has been, getting the most Fly Time from a quad; I have logged a lot 
of data, researched, listened to others, and done my own experimentation.

For some time now, there has been a sort of "debate" about which provides longer
Fly Time. Is it higher mAh or more cells per pack?  
1) more mAh with less cells or
2) more cells with less mAh. 

Right up front one CAN NOT say that a 4S 650 mAh provides longer times than a 
3S 650 mAh battery without considering the weight differential. With these small
craft weight is always an issue. 

In theory, any 2 batteries that have the same energy, Watt Hours ( Wh),
should provide the same Fly Time, but that is not precisely true because we
have not yet introduced the weight factor. What we are REALLY looking for is
the energy per gram, Wh / grams within the battery allowance for the quad. 
For any given weight or battery allowance, the battery with the heighest Wh/g 
should provide the longest Fly Time. 

To make the comparison easier, this information is listed on the Batteries Tab in
My Parts Guide <-- click to download.

NOTE:  I have been assembling battery packs from the time I moved from 1S
           tiny whoops to 2S quads. In fact, one can even buy pre-built adapter
           cables for the small whoops. Also, the EMAX TinyHawk Freestyle came
           with a power pigtail for two 1S cells. Some will chime in about the added
           weight of the connector assembly so there is that but, it ABSOLUTELY
           CAN be done.

           Also, a multi-cell pack can be split to form smaller packs or even single
           1S cells since the smaller cells seem to be limited in the higher mAh
           ratings. 

Regardless of the technical reason, it seems that increasing the mAh for a given
cell count provides better Wh/g than adding more cells with the same mAh. For
flight time a move to more cells tends to happen when an mAh ceiling has
been reached. The established long range pilots have known this for years.

However, it is not about opinions, it is about getting that Fly Time increased! Right?
.........................................................................................................................

Hi fpvapnea,

Good job on making that battery pack. 

Yeah i guess by experimenting and natural progressing in my new hobby i discovered what you just described . Thanks for your research over the years , very usefull info !!!
As proven again there is no substitue for years of experience other then years of experience. I know that from my own field of work in IT.

(25-Nov-2022, 08:24 PM)fpvapnea Wrote: Yeah i guess by experimenting and natural progressing in my new hobby i discovered what you just described . Thanks for your research over the years ,   very usefull info !!!
As proven again there is no substitue for years of experience other then years of experience. I know that from my own field of work in IT.

Hi fpvapnea,

If you ignore the AUW contraints then bigger is always better, Right?  Until it Isn't.

Let me say up front that there are all kinds of dicussions {to say the least} about 
the sub-250 gram, category 1, FAA  quads. Some care and some don't. Well, I care.
If a person does care and wants to stay below that line that the FAA has drawn,
then the weight of the battery absolutely matters.

For a sub-250 gram quad, a battery allowance of 100 grams is pretty much the
limit. Yes, one could marginalize other componentes to get a few more grams 
for the battery, but realistically 100 grams is a pretty good average. 

Consider the following batteries and what you get for the 100 gram weight:

6S GNB 650 mAh 100 gram 14.82 Wh =  0.148 Wh/gram

4S GNB 1100 mAh 92 gram 16.72 Wh =  0.182 Wh/gram

3S RDQ 1100 mAh 68 gram 12.54 Wh = 0.184 Wh/gram

3S GNB 1550 mAh 100 gram 17.67 Wh = 0.1.77 Wh/gram

Notice that, for the weight, the 6S would likely be the worst battery 
in the bunch for the BEST fly time. 

My standard, default, battery is the 3S GNB 1100 mAh battery 
that weighs 67 grams which puts it about equal to the RDQ one. 

Now, most of my quads can not use anything larger than 3S and 
I only have one "Heavy" build that is a 6S and that puppy is running a
large 6S 1100 mAh 133 gram battery. I also have a 4S GNB 1100 mAh
battery with an actual weight of 88.9 grams; so eventually, I will try 
that one in my heavy Rescue Quad, but that is the only quad it will
work in. 

Cool, your experience proved my deductive results EXACTLY. Beginning of this week i ordered 6 X 3S GNB 1100 lipos as looked the best based on weight vs mah. Thanks for confirming .
Now just wait only 2 months for they get here.......
But at least i have 2 of my parralel 2x2s kits with just a slightly less Wh/g total capacity (0.163) that give me a comfortable 8:45 min avg flight time for this little overweight micro quad.