With my focus on sub250, I've been very meticulous about documenting the weight of every single component down to individual screws.  No joke, here's a zoomed out view of my "data sheet" where I log every frame part, electronics, motor, prop, nut, and screw with info on what they cost, where I bought it from, how many I bought, and most importantly for sub250, weight ...



After all these builds and analyzing weight, the following rule of thumb became evidently clear early on for sub250 builds ...

75% of the AUW is informed by three components:
the lipo (35%)
the frame (20%)
the motors (20%)

So I started to look for more data to come up what representative, average weights might be for the major components.  The idea being that with these general buckets, I could lay out an array of possible builds and come up with a heat map or cheat sheet, so to speak, to give me a quick idea of what can and can't be done from a sub250 perspective at a quick glance.

[Image posted at the bottom of this post since it is super long.]

I basically have data next to labels and using a vlookup to find the weight. I then used conditional formatting to format the components based on the cumulative sum of weights. Anyway if you wanna get into the Excel nitty gritty I'd be happy to share the file. I'm sure there's a better way to present this but for now I just wanted to get it out in the wild.  I'm thinking Google sheets or something using data filters.

Basically, it is an array of possible 3-inch and 4-inch builds across different components:
*  lipo size
*  motor size
*  FPV system
*  HD camera

The color coding provides a visualization of what builds remain sub250 and to what degree (refer to the legend above the chart for details).

In putting together the buckets of components, I looked at approx 40 lipos (HV and normal) and 30 motors (14XX-200X).  The 3-inch and 4-inch frame weights reflect where my own designs are coming out.  Components reflect what might be reasonable for a sub250 build thefore no motors bigger than 200X are considered.  Additionally, the DJI FPV system reflects Caddx Vista and Naked only.  Based on my own prior builds, an avg of approx 40g of "other components" is reflected in the calculation.  I am also only looking at 4S lipos since that seems to be the sweet spot for sub250.  Lastly, the HD Cameras considered are the Insta360 Go v1 for 1080P and the Go v2 and SMO 4K for 4K.

As a sanity check, my latest iteration of the 4-inch Ronin Mk2 equipped with GNB 660mAh HV 4S lipo, 1504 motors, HDZero, and an Insta360 Go v1 clocks in at 249g on the dot ...



My latest 3-inch Sohei Mk2 is also using the GNB 660s, 1404s, HDZero and rocks the SMO 4K ...



Again, this "cheat sheet" is really focused on sub250 builds and, in particular, roninUAV frames.  I plan to incorporate this into the website so people can quickly get a sense of how to approach their builds before they even buy the frame.

Here's a cool take away as I stare at this thing for hours lol ... it looks like 200Xs on the 4-inch is going to be a tough one ...



I need to be ok without having an HD cam and using tiny lipos. But at least I can use HDzero or DJI. Yea this is cool lol.

I assume "DJI" + "None HD Camera" means Caddx Vista, and DJI +"1080p" means Air unit?

(05-Feb-2022, 08:10 PM)leestrong Wrote: I assume "DJI" + "None HD Camera" means Caddx Vista, and DJI +"1080p" means Air unit?

Quote:Additionally, the DJI FPV system reflects Caddx Vista and Naked only.

Quote:Lastly, the HD Cameras considered are the Insta360 Go v1 for 1080P and the Go v2 and SMO 4K for 4K.

Thanks Ronin, this is very informative!
I wonder if 200X motor + HD cam is achievable with even lighter batteries, such as 3S 300mAh GNB @29g
(You know theoretically, if it can lift off, it gives plausible deniability....not that I advocate flying above 250 without registration, hmm no sir.)

That would work. But 3S 300mAh I don't think is just gonna give you any power to really play with at all.

According to the data, you might be able to pull off 200X on 4 inch with 450-500 lipos with HDZero onboard but no external HD cam.

Personally, I really think 200X is overpowered for sub250 in general. I really think 150X is the sweet spot for 4 inch and 140X for 3 inch. To clarify, if you were not sub250 then sure 200X is likely appropriate especially if your carrying around a GoPro.

Wow! This is really detailed and I can see how it would help make decisions easier when trying to cut weight for a build. It reminds me of a spreadsheet a former manager shared with me. He and I backpack and he had created a database of all his gear with general size and exact weight. He used it to figure out what his pack would weigh for given trips. I was never motivated enough to plug in all the data to use it.

Its not that complicated. For sub250g, stick to 4".

I dont like 15g 2004 for 5". You get a lot zoom and fun by going up to 20g+ like 2204.
Remaining weight budget makes 5" "doable" but immpractical, and for DJI Air, useless.
All my 5" ultralights come in a little over.. 280g, 305g. Makes HUGE difference, and its worth it.

Why does 4" work?
- save 5-10g on frame
- XT30 & thinner wires
- save 4g on props
- and big one -> you only need 10-12g motors.

You missed the part about the onboard HD cam. Still not so complicated?

Wow, just came across this. Nice work dude and thanks for sharing. Very helpful for those who want to do the same. I have been thinking about building one in the near future and was starting to get lost with so much to look into, this will be of great help.

Hi Ronin,

Nice work. Very comprehensive and good comparison guide.

Like you, my primary focus is sub-250 gram quads and I do collect data on
my builds, however, I don't have near the volume of information that you have 
compiled. Still, I am arriving at some similar, if slightly different, conclusions. 

My general conclusions are not focused on any particular type or style of
flying or any particular performance criteria. I leave that to the individual
builder/pilot. On the one hand, there are certain generalities or realities
that are inherent in a sub-250 gram quad. On the other hand, any one
area can be compromised for another area depending on the purpose or 
goals of the builder/pilot. 

The goal or purpose of the quad dictates where to compromise and where not to.

I believe your percentages to be a pretty good baseline.

My perspective is that a quad has 4 major subsystems:

1) Electronics,  2) Frame,  3) Drive Train , and 4) Power (Battery) 

1) Electronics: 
                    Anything that is electrical {except the motors} including the FC, ESC, GPS, 
                    Camera, VTX, Receiver, Etc. The weight of this package is, or might be, 
                    pretty consistent for a given builder especially if someone uses the same 
                    components for most or all of their builds. This package also includes any 
                    HD gear and Action Cams. Typically, I solder up the electronics on the bench,
                    test it on the bench, then "drop" it in a frame.  In my analog builds, 
                    I allow about 50 grams.
                     
2) Frame:     This is the actual frame plus all of TPU stuff, hardware, special braces, etc.
                    The frame package has some flexibility, particularly in TPU accessories.
                    Size matters here. A bare frame at the top sizes might weight 50 grams  or
                    more depending on size and construction. 

3) Drive Train: 
                    Motors, Props, and all bolts or nuts. I have noticed that the size of the 
                    motor is not always indicative of the weight. Some smaller motors weigh more 
                    than some larger motors. Also, T-Mount motors weigh less than 5mm prop shaft
                    motors. Plus, there is a wide variance in prop weight depending on the number
                    of blades and the mount type. Consequently, there is a pretty decent range of
                    combinations depending on the desired characteristics and thrust. Allowing
                    about 60-70 grams is about average. Much over that and something else will
                    need to adjusted. Yeah, a 20 gram motor is really too much; it can be done, but
                    weight allowance will need to be reduced somewhere else; maybe the battery.
 

4) Power:    This is basically the battery, but could also be solar or other type of power source.
                    Again, there is a wide range of possibilities depending on the desired effect. 
                   The pendulum swings from Hi-Performance to Endurance (Long Fly Time).
                    The Hi-Performance pilot desires a certain acceleration rate and battery
                    recovery needed for power punches and stunts. The endurance pilot is 
                    generally more focused on maximum Fly Time and perhaps long distance.
                    The performance minded go for 4S or even 6S batteries. The endurance
                    minded might find better range with a 3S or even a 2S Li-Ion pack. Now,
                    the battery allowance might range from about 70 to 100 grams; maybe a bit
                    more if one of the other packages can be lightened up.

Adding this all up:
1) Electronics    50 grams
2) Frame          50 grams
3) Drive Train    70 grams (let's be generous, but not up to a 20 gram motor)
4) Power          79 grams  (that GNB 4S 660 mAh 90C battery weighs about 63 grams)
                -------------------
Total             249 grams

Notice that the Drive Train (motors & props & bolts) and the Power (battery) are over half of the
weight. If you have big motors, then you can't have a big battery. If you want a big battery then
you can't have big motors. Somehow, these two sub-systems need to balance.

Keep in mind if we can reduce the weight in one package we can increase the allowance in another.

In my opinion, Ronin's builds fall nicely into this general pattern and he has an ability to 
optimize how his frames could be built to produce a decent performance craft. 

From my experience, my research, and my observations; my predictions are as follows:

Anything less than 3 inch will be fun machines that can do ACRO stunts, but not the all out performers.
This size might also become a decent cinematic platform and will include whooped quads. These will
be nice little "Fun" quads and good to learn on. 

The 3 inch or the 3.5 inch will end up being the high performance ACRO quad. Keep the weight as light
as possible and use a powerful Drive Train. I predict that, eventually, this will become what the 5 inch is 
now.

The 4 inch, 5 inch (maybe larger) will be the endurance, long range, craft because a Drive Train to 
provide the necessary acceleration for hi-performance will simply be too heavy. Ok, maybe 2 minutes 
on a 300 mAh battery. But seriously, these will be more endurance than performance. This size will 
become what the 7 inch to 10 inch and up has been.

   {Edit 2022-05-22}  It seems that an 8" sub-250 gram quad is actually workable.
                               Have watched videos by "The Red Baron", I am impressed by
                               the 8 inch build. Ok, the quad is built on a 7 inch frame and 
                               the batteries for sub-250 are not overly large, BUT it can be 
                               Done. Check out the Video in this post.



Now we are talking true sub-250 grams AUW quads including battery and all payload. 
Not cheating. Not a quad that is sub-250 with a 3S 300 mAh battery, then you strap on 
a 4S 850 mAh and go fly.

In an effort to provide information for the sub-250 gram builder, I maintain a spreadsheet of 
components to serve as a guide and comparison for sub-250 gram builds. Although I do try
to maintain it, the list is more of a representative sampling than an all inclusive one. 
My Parts Guild <-- click to download, is an Excel spreadsheet that is also downloadable 
from the link in my signature line which is included on all of my posts.


.

As I work on my 6 inch GT-LT6-X1 build, I am seeing things from a slightly
different {or maybe more refined} perspective on building a sub-250 gram quad. 
Although the core concepts are the same, this is just a little different way to look 
at it.

For a sub-250 gram build, the weight really breaks down into 3 categories:

1) Battery ...........................  100 gram allowance
2) Electronics ......................    50 gram allowance  <-- Including Action Cam
3) Frame + Drive Train ........   100 gram allowance  
                                        ----------------
                                            250 grams  (Yeah, take 1 gram from somewhere)

I have put the Frame and Drive Train together since this is where a balance of
compromises comes in. The heavier the motors, the more the frame weight needs
to be compromised. If both are heavy, it just pushes the weight up too much.

There may be a little buffer space in the Electronics; or maybe not. It all depends
on what you run. I run analog and use pretty light components, however, I do use
pretty decent antennas. A digital system may be heavier. I also generally run a GPS 
module. Everything counts. Now, what ever you use, the weight of the Electronics
package likely will be pretty consistent regardless of the build.

Finally, you have the battery. If you are a short run ACRO pilot, then you might opt
for a smaller battery in order to reduce the weight which can be used for something
else; maybe motors. If you are an endurance pilot, you likely want extended flight
time which takes a pretty decent {large} battery. Personally, I try to allow 100 grams
for the battery even though I mostly run batteries that weight about 70-80 grams.
However, I still like to have the option to run a 2S Li-Ion battery which weighs about
100 grams. 

Battery Options that are 100 grams or less:

4S 1100 mAh 16.72 wH   92 gram GNB or any 4S that is 1000 mAh or less.
3S 1550 mAh 17.67 wH  100 gram GNB or any 3S that is 1100 mAh or less. 
2S 2000-3000 mAh 100 gram Li-Ion pack. {you might think this marginal; maybe it is}.

The size of the props is more or less an irrelevance as long as the motors will spin them.
Keep in mind the AUW is still less than 250 grams so the "load" on the Drive Train is 
pretty close to the same whether the build is a 3 inch or a 6 inch {or even 7 inch}. 

At 7 inch {or 8 inch if you are The Red Baron} we are reaching the prop size limit for a
sub-250 gram build. Anything larger will likely require a larger frame {more weight} and
maybe larger motors. These will definitely be endurance cruisers since motors to accelerate
the larger props to any hi-performance level will take the build beyond 250 grams. 
Consequently, the larger builds will likely be cruisers rather than Freestyle, ACRO, performers. 

To use heavier motors, the build needs a lighter frame {say about 20 grams} which you
might get in a 3 inch frame, maybe. The battery allowance could also be reduced for an
ACRO performer so that heavier motors could be used. This is why I predict that, in the
sub-250 gram category, it will end up being the 3 to 3.5 inch quads that will be the 
hi-performance, Freestyle, ACRO, and racing craft.