2022-06-12     GT-LT6-X1          (sub-250 6 inch)     

                                       Build # 16          Last Post            My Journal             
   
GT-LT6-X1  is build #16 and is intended to be a sub-250 gram 6 inch craft.
Even though this is a 6 inch build, it is not intended for Long Range, so I am 
posting this in the Mini-Quad section. The quad will be a very light weight cruiser. 

The frame is one of gt40's custom designs. Thank You gt40.
Contact gt40 if you want one of these frames.

It is the same frame used in gt40's   custom 6" lightweight build .

I really like the design; It is very strong, very light, and looks really COOL    
My bottom plate weighed in at 32.4 grams; the top plate weighs 4.5 grams;
this brings the total frame weight (less any hardware - not supplied) to about 
36.9 grams. This is the lightest 6 inch frame that I have seen so far. Plus,
it is drilled for 20x20, 30x30, and 26x26 whoop FC boards.

I just had to have one. With this frame, I believe that I can build a decent 
sub-250 gram 6 inch quad. WOW !!! 

My goal is to have a nice 6 inch cruiser that fits my easy cruising flying style.

It will be interesting to see how my build compares 
to gt40's  custom 6" lightweight build .





_______________  PARTS LIST ___________________________


Frame:                  Custom 6 inch design by gt40
Cam Brace:      

FC:                       iFlight BEAST H743 55A AIO (whoop)

Motors:                 BrotherHobby VY 1507 4150 KV w 5mm prop shaft  
                            HGLRC Aeolus 1804 3500kv T-Mount 
                            
VTX:                    
VTX Antenna:                                                 
     
Camera:                Foxeer Razer Nano 1200 TVL   <-- this is my standard  camera.
Camera:                Caddx Baby Ratel 2
                                
Rx Receiver:          FrSky XM+ (ACCST)   <------- I have a bunch of these in the parts bin.
RX Antenna:          included with receiver                    
GPS:                     Matek M8Q-5883                                                             
Capacitor:             1000 uf 35V           <------- I have a bunch of these in the parts bin.        



Props:   


==============================================================
2022-07-19

I have found enough components in the parts bin to complete this build.

There was an unused JHEMCU GHF405 35A AIO that I have had for a while now,
so it very likely has all good chips on it. I bought this before all the chip shortages.

Of the motors that I have found, I think that the BrotherHobby 1507 4150KV motors
should work just fine since the 1504.5 version of this motor spins 5 inch props just fine.
Since the 1507s have a 5mm prop shaft, they will work with the variety of props that
I have with 5mm hub hole; 6 inch, 5 inch, and maybe 7 inch {yeah, 7 inch props will
actually fit on the frame}. Even with the 6 inch props, I will offset the motor height 
on one of the diagonal motor sets as the clearance is extremely tight. With the offset,
the 7 inch props will also work. These motors weigh 16.5 grams each with wires.

These motors and the frame are coming in a about 100 grams. That leaves me a
50 gram allowance for the electronics and props. If I can get this thing built with
a dry weight at 150 grams, then I will be very pleased. 

I found a Caddx Baby Ratel 2 which I want to try. If I like it, then I will keep it,
if I don't, then I will swap it out for the Foxeer Razer Nano.

2022-07-23

I plugged a USB cable into the JHEMCU GHF405 to work on the Betaflight settings,
however it would not power up. Grrrr. So...back to the parts bin. I have a brand new
(Mfg Date 2020) iFlight BEAST H743 55A AIO (whoop) that I will use. Hey, why not.
This is a good build for that FC. 

The BUILD continues:

This will be the actual build process.

maybe an unify nano pro32 at 1g, as no lr is aimedi would use the lightweight stock dipole.

what motorsize and voltage will you choose for your goal or what directions do you aim?

(13-Jun-2022, 12:12 AM)hugnosed_bat Wrote: maybe an unify nano pro32 at 1g, as no lr is aimedi would use the lightweight stock dipole.

what motorsize and voltage will you choose for your goal or what directions do you aim?

Hi Bat,

Since I don't fly ACRO and this build wouldn't be that anyway...it is an "easy cruiser" 
so I don't need a lot of "hi-performance" ... just need enough to take off and cruise.
So... I am thinking something between 1507 and 2004 motors with high enough KV
to only need a 3S battery. I want Fly Time, not 2 minutes of gut wrenching stunts.
Also, I want to keep the total motor weight as much below 80 grams as I can get.
I would like to keep the frame and motors less than 120 grams.

I haven't decided on the VTX, but I will want it small. I actually have a couple that
are very tiny one...yeah, I don't need super high mW. Yeah, I might just use the dipole
that comes with the VTX. Keep it light. 

I will try to use the supplied top plate, but will fabricate my own if I need to. It
just depends on how things fit together. I do want the battery on top so that will
have some bearing on the build. 

It will be interesting. 

2022-06-27     UPDATE

This build will be delayed a bit due to receiving two Faulty FC boards.
I had purchased two JHEMCU GH743 F7 40A AIO (whoop) boards;
one for the Rescue Quad and one for this build. Sadly, both boards 
have failed. So, now I am looking through my parts bin to see what
FC boards I have that might be used. The first board will go in the
Rescue Quad. If I find a second board, it will go in this build. What
I don't find, I will have to buy. So, we will just see how much things
are delayed by this little issue. 

2022-07-09

With the Rescue Quad back together and operational, I will be getting
the parts ready for this build. I am anxious to see if I can build a nice
sub-250 gram 6 inch cruiser. Since this one doesn't have to be a heavy
lifter nor a "Hi" performance craft, it will be based on 2S-4S components.
I will start with my standard 3S 1100 mAh GNB battery which weighs 
about 70 grams. The finished dry weight of the quad will determine my
final battery weight allowance. I strive to allow 100 grams for the battery
so that I might run a 2S 18650 pack and larger 4S batteries, however, 
75 grams will still work for me which would still allow for a 4S 660 mAh 
battery.  

Now, I need to go through my parts bin and see what I have on hand.

2022-07-19

In the parts bin, I have found all of the components necessary to complete
this build. 

I found a JHEMCU GHF405 35A AIO that was purchased before all of the 
chip shortages started effecting products. So...I am hoping this board will 
be quality and work for me without any issues. 

Of the motors that I could find, the BrotherHobby VY 1507 4150KV 5mm shaft
motors should work fine and easily handle the 6 inch props. 

At this point, the frame and motors are coming in at about 100 grams. NICE.
That leaves 50 grams for the electronics and props to keep the dry weight at
about 150 grams. This is the goal. 

I have also found a Caddx Baby Ratel 2 camera that I want to try so it will be
mounted first. If I like it, then I will keep it, if not, then swap it for the Foxeer
Razer Nano. 

Since the Rescue Quad is together and awaiting testing, I will have some time
to work on this build. 

In searching for alternate motors, I have just purchased a set of HGLRC Aeolus 1804 3500KV
12.7 gram T-Mount motors which are 3.8 grams lighter than the 5mm shaft BrotherHobby 1507's.
Additionally, the T-Mount 6 inch bi-blade props are lighter than the 6 inch 5mm shaft props.
So, this change will reduce the weight by about 20 grams. The 1804s have a little less stator
volume than the 1507s, but I don't know what, if any, difference this makes.

So, potentially I will have 2 motor options. Which one I end up with will depend on the
weight of the electronics package, any additional plates, and any frame hardware. I really
want to keep a 100 gram battery allowance, but could marginalize this to a some degree.

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}.

As I work with this sub-250 gram 6 inch build, I am coming to the following conclusions:

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)

In reality, the only way this build is actually possible is the use of a light weight frame.
Thank You, gt40, for a nice 32 gram 6 inch frame... AND Keeping the motors and props 
to about 15-16 grams. The total Frame, Motors, and Props needs to come in right at 
100 grams...and NOT much more or you will need to compromise something else.

There may be a little buffer space in the Electronics; or maybe not. I do intend to use
a GPS module and I won't compromise on the VTX antenna; plus I may use a TPU
whoop canopy to mount the camera.  Everything counts.

It will be interesting to see if I can run 7 inch props and keep the AUW less than 250 grams.

The size of the props is more or less an irrelevance as long as the motors will pull 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}. 
That said, 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 be the 3 to 3.5 inch quads that will be the hi-performance
craft. 

So, now I can work on the electronics while I wait for the new motors to arrive.

The wider 1804’s should be more efficient and stable in the low to mid throttle range, while sacrificing some of the high end speed/power of the taller 1507’s.

Slightly less stator volume will mean slightly less torque.

That’s my understanding of it anyhow- I could be wrong.

(20-Jul-2022, 09:40 PM)Lemonyleprosy Wrote: The wider 1804’s should be more efficient and stable in the low to mid throttle range, while sacrificing some of the high end speed/power of the taller 1507’s.

Slightly less stator volume will mean slightly less torque.

That’s my understanding of it anyhow- I could be wrong.

Hi Lemony,

Yep, that's pretty much how I figure it; the motors are more or less equivalent especially 
for the way that I fly. It will really come down to weight which I think the 1804 T-Mount
motors have it over the 1507 5mm shaft ones...including props.  So, if I am tight on the
weight it will definitely be the ones that weigh less. On the other hand, I will consider
the 1507s if I have extra allowance for it. That is, the dry weight with the 1507s is 145
grams or less. I really want this to be a sub-250 gram craft and still have 100 gram
allowance for the battery. The dry weight simply can not exceed 147 grams. Yeah, 
that leave 2 grams margin in there. We will see how it goes. 

By the way, I have 6 and 7 inch props in both 5mm and T-Mount. That's right, Gemfan
makes a 7 inch with they "hybrid" mount that will fit on T-Mount motors. NICE. So, I
will be able to run both 6 and 7 inch props with either motor. 

2022-07-23

The HGLRC Aeolus 1804 3500Kv motors have arrived. These T-Mount motors only 
weigh 12.6 grams. With a Gemfan 6 inch prop, the weight is 15.7 grams. On the 
other hand, the BrotherHobby 1507's with 5mm shaft weigh 15.7 alone; with a similar
bi-blade prop the total is 21.8 grams. That is a 6.1 gram difference per motor/prop
set. Yep, the full drive train using the 1507s with 5mm shaft is 24.4 grams more than 
the 1804 T-Mount set.

If I use the 1804s the total drive train weight is only 62.8 grams; these and the 32
gram frame will be less than 100 grams total. Now, we are talking. That will give me
a solid 50 grams for the electronics and still leave 100 gram allowance for the battery.
This will also allow a little head room for the 7 inch props. 

I plugged a USB cable into the JHEMCU GHF405 today and NOTHING !! No lights 
at all. I am not even going to think about debugging at this point.  Ok, so let's use 
the iFlight BEAST H743 55A AIO (whoop). Why not? Let's see if we can get this 
thing wired up and working. 

Man, you seem to be having a bad run with JHEMCU fc’s lately. They were my favorite brand for cost/durability. On the off chance the same thing happens with iFlight beast, maybe try a different usb cable.

That is a significant amount of weight savings with the 1804’s.

(23-Jul-2022, 10:03 PM)Lemonyleprosy Wrote: Man, you seem to be having a bad run with JHEMCU fc’s lately. They were my favorite brand for cost/durability. On the off chance the same thing happens with iFlight beast, maybe try a different usb cable.

That is a significant amount of weight savings with the 1804’s.

Hi Lemony, 

Yeah, I really thought the F405s would be ok since they were bought before the chip crisis.
I have had very good luck with them in the past. This is sort of FREAKING me out. 

It is not the USB cable. That said, I will try a different cable just to be sure. On the other hand,
The BEAST fired up just fine. I am back on track. I have been wanting to use this FC, but just
didn't want to put it in a small quad or whoop. Yeah, this thing would fit my Tiny-Black-85, but
Man, talk about overkill. A 55A board in an 2 inch whoop. I have sort been saving it for an
appropriate build. Well, I guess this is it. It seems that I am quickly clearing out my stock of
FC boards. 

Yes,  the weight difference between the 1507's and 1804's is quite significant. Using the 1804's
will give me some breathing room in the weight department. 

A few years ago, everyone would think that I am crazy {well, maybe I am...or at least eccentric}
for pairing 1804's with a 6 or 7 inch prop. However, I have come to a realization that is slightly
different than "Old School" thinking. They refer to the motor not being able to spin the prop, 
however, this is not exactly the case. The motor will definitely spin the prop, however, the
real issue is how much the motor loads trying to lift the weight of the craft...not the prop by
itself...and how much acceleration power you have; how fast the motor spins up. Again, it
is not just the prop, but rather the load. In the old days {of just a few years ago} a 6 or 7 inch
quad weighed, what, 500-700 grams {maybe more with payload}. So the real question is how
much it takes for the drive train to pull all that weight. NOW, a 6 or 7 inch quad that only weighs
150 grams dry weight is quite a different thing. The thrust requirements are quite different. 
It just doesn't take a bazillion pounds of thrust to lift. Plus, if you don't ask the motors to go from
idle to 10,000 RPMS in 0.5 seconds, well...you just aren't loading the motor as much.  The real
load on the motors is what it takes to lift the quad, NOT what it takes to spin any given prop. 

Anyway, we are going to see how those 1804's perform...
to spin or not to spin...that is the question.