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Author Topic: Sub 250g racer  (Read 1924 times)

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Offline zeronest

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Re: Sub 250g racer
« Reply #30 on: July 25, 2017, 04:36:36 »
So I really can't comment on the durability for a given width of carbon on a quad this light, I know all about 5 inch quads that are up around double the weight if this, but they carry double the momentum and thereby the force into an impact, at a basic level my mechanics says actually the use of 2.5mm carbon whole be as strong as 4mm on a traditional 5 inch quad :)

But comparing your carbon weight, it is considerably less than the air-ro which uses 3mm and very similar to the CMW which uses 2.5mm which, given all three are fairly similar in size, suggests the baseplate is 2.5mm

But as above seems unimportant

ATM struggling with the 5 inch build, weight seems to be the killer, the 4inch can potermtially use 650mah lipos and get reasonable flight times, which gives a lot more space to play tag with :)


Ah I see, looking at it that way you could be quite right, well a good way to estimate at least..

I thought about 650 packs my self but didn't know if they could supply enough amps and would sag, The infinity 850 70c can supply around 60a which is probably about right in flight..

another pretty cool thing with these style of builds is the ability to run something like a 850-1000mah 2s battery and they fly pretty efficiently and long flight times, I have a small garden, but still fly-able and often shred around on 2s  and as it weighs next to nothing with such little battery weight, crashes really do no damage

Nice frame that thanks  ~~

No thank you!  :smiley:

Offline atomiclama

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Re: Sub 250g racer
« Reply #31 on: July 27, 2017, 11:34:10 »
Just a thought, have you considered stripping the battery down. I know some packs have extra layers of reinforcement in them which could be removed.

Could save a bit with shorted leads, xt30 and reworked layers.
Wasdale X, Ow that hurt

Offline Cheredanine

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Re: Sub 250g racer
« Reply #32 on: July 27, 2017, 11:36:19 »
It's a good thought mate, I am already intending to shorten leads and use xt30

There is quite a variation in weight for the 850mah but on a personal level I am not keen on messing around with the cells

Will see where I get to :)

Offline Cheredanine

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Re: Sub 250g racer
« Reply #33 on: July 29, 2017, 13:54:32 »
Some bits from rotorgeeks arrived,
Still got to add:
Tbs unify and xm+ (8g)
Fc (14g) and xt30 pigtail ?

As you can see hat will push me over 250g by 6 grams

However:
1 have replacement titanium bolts for top
2 motor wires need trimming to fit
3 lipo will switch xt60 for xt30
4. Those props may be slightly heavy
5. Low profile lock nuts on the way
6 intend to trim the cam mount
7. Obviously the lense caps weighs a lot, should have taken it off before I took the pic
8. Depending on flight time could use 650mah lipo
9. Could even use 3s!

Will see where I get to when fc arrives next week


Offline Cheredanine

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Re: Sub 250g racer
« Reply #34 on: July 29, 2017, 14:31:47 »
Switched the props, this looks a whole lot better (also added titanium bolts and removed lense cap)



Offline Cheredanine

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Re: Sub 250g racer
« Reply #35 on: August 02, 2017, 21:22:50 »
And done:



That is with 650mah 4s

With 850mah 4s it is 254g

Will test flight times before I trim any more weight

I just test hovered with a 3s 650mah, it was very sensitive and agile, 850mah 3s may be the way to go

Edit, ordered optipower 850mah 4s, 4g lighter than the tattu and has a long pigtail with xt60, by the time I shorten and add xt30 should be fine

Turnigy nanotechs would also do it
« Last Edit: August 02, 2017, 22:10:46 by Cheredanine »

Offline Bad Raven

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Re: Sub 250g racer
« Reply #36 on: August 03, 2017, 13:08:44 »
Good stuff!  ~~ ~~

When you are happy with it and its reached a stable normal fly state, I'd appreciate a few zoom able photos against a light background, studio style.

Offline Cheredanine

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Re: Sub 250g racer
« Reply #37 on: August 03, 2017, 13:19:54 »
No worries mate, once I have finalised and got data on motor/lipo combos will put up some detailed photos

Offline Samslimer

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Re: Sub 250g racer
« Reply #38 on: August 03, 2017, 21:10:19 »
Have to say I'm very impressed. After you have a feel for it in flight, along with some photos, would you mind giving your definitive build list of parts? With your preferred choice of components. Definitely looking to build one after seeing this.

Offline Cheredanine

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Re: Sub 250g racer
« Reply #39 on: August 04, 2017, 00:14:03 »
There are parts I have used on this I would not use on a finished article, mainly the asguard, I am using it because it is a light aio with current sensing, but the kisscc is lighter, just doesn't have osd or sd card.  If the frame was single baseplate that would save 6 grams. Adding 20mm mount holes  would allow micro fc to be used and 20mm 4 in 1 escs, all of which are weight saving.
If I didn't have the osd on the fc I would use an arrow micro as they have voltage displayed on the fpv
A redesigned top plate would be lighter and allow better mounting options, I considered a top mount fpv cam rather than fromt, but felt it would be too exposed.  There is an axii antenna with a ufl adaptor out, that may be a better option than the dipole

Some stuff I wouldn't change, the motors for example, only the rotorgeeks and dys se1407ii are that light most are at least a gram and a half heavier, doesn't sound like much but when you have 4 motors it starts to add up, suddenly you are 10g over.

Once I get some testing on the different motor/prop/lipos will post with details on what is a must and why I think it is a must and what is flexible

Follow members gave a thank to your post:


Offline zeronest

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Re: Sub 250g racer
« Reply #40 on: August 05, 2017, 19:32:48 »
great build and auw looks super ~~ ~~

Offline Cheredanine

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Re: Sub 250g racer
« Reply #41 on: August 10, 2017, 13:54:50 »
So having burned the asguard (human error) replacement finally arrived (also burned one of the 3200kv motors, replacement next day or so).
Rebuilt with the 2800kv.
Test hover nice.
Should get it flying again this evening with a bit of luck
Thus is with optipower 850mah 4s:



Offline Cheredanine

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Re: Sub 250g racer
« Reply #42 on: August 10, 2017, 23:58:45 »
Flight times:

Rotorgeeks 1407 2800kv
Gf5030
859mah 4s
6 mins

As above, except racekraft 5038
5 mins

As previous except 650mah
4 mins

Pretty dull but example flight style giving those times (with 850mah 4s, gf5030) stock pids and filters :


The 5038 feel like they pull too much for 650 mah. Serious voltage sag, no speed improvement I noticed

Offline shawdreamer

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Re: Sub 250g racer
« Reply #43 on: August 11, 2017, 09:53:33 »
those low end voltage spikes must feel pretty noticable if their showing up that clearly on your OSD?

what C rating is the battery for it to be that sharp?

saying that tho, she looks quite stable considering its stock PID's
550 custom H-copter
zmr250
Reaper250 V.1
Reaper250 V.2
ViceVersa250 XL
zmr250Hybrid
https://www.thingiverse.com/shawdreamer/designs

Offline Cheredanine

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Re: Sub 250g racer
« Reply #44 on: August 11, 2017, 11:26:31 »
Flying fine on stock, not convinced any of the oscillations are not the camera mount which isn't hugely tight on the standoffs since I had to mod it. At some point I will put an sd card in and check the bb logs, but if handles fine ATM and motors cold as stone when it comes down, with so many things being changed it would be a waste of time fine tuning it

Lipo there is an optipower 850mah 4s 50-100c with leads shortened and xt60 replaced with an xt30

I do think 3200kv is gonna be the sweet spot, waiting for replacement motor :( I can cope with less flight time for more speed
« Last Edit: August 11, 2017, 11:31:10 by Cheredanine »

Offline Cheredanine

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Re: Sub 250g racer
« Reply #45 on: August 14, 2017, 15:21:53 »
And 3200kv video
This is with hq5030 glass nylon
I tried some 5045 but they are firstly too heavy (251g with my lightest 850mah) and any sort of punch kills the lipo (I can get voltage alarm on a punch takeoff with a full lipo)

I have some hq 5040 carbon/nylon on the way to try out, but suspect they will be lipo killers also

Caveats on the vid-
Pretty boring, people were wandering about speed so this is less acro, more push, on a light quad there is more of a tendency to gain height on hitting the throttle, need some practice I think to master
Also still not tuned, motor 4 has some vertical play but gives so,e indication of speeds and flight times;


Offline Cheredanine

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Re: Sub 250g racer
« Reply #46 on: August 15, 2017, 16:26:13 »
Interesting, I ordered the wrong props, got 5045 carbon/nylon

Thought I would spin them anyway and lipos pretty much coped, right up to the point I got hit by a ghost branch and destroyed a motor

There appears to be a standard rule here on 1407 with 5 inch - light rigid props (carbon- nylon or glass-nylon) work far better than nylon

Refitted the 2800kv (whilst replacement 3200 is on its way) and heading out to try

Offline Cheredanine

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Re: Sub 250g racer
« Reply #47 on: August 15, 2017, 22:09:02 »
And resultant speed tesr (flight time flying like this about 3mins 30)

Offline Cheredanine

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Re: Sub 250g racer
« Reply #48 on: August 17, 2017, 14:13:29 »
Fastest prop then: hq5040 carbon-nylon on 2800kv:


SUMMARY:
Best to use glass-nylon or carbon nylon props, pure nylon flew worse and were less efficient

Acro:
2800kv or 3200kv with 5030 works very well with big (over 5 mins) flight time

Racing/speed:
Best was 5040 on 2800kv

5045 were not far off on either 2800kv or 3200kv but slightly less top end and a plateau towards the top of the throttle
Be careful on 3200kv, a bit heavy on the lipo

Offline Bad Raven

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Re: Sub 250g racer
« Reply #49 on: August 18, 2017, 08:11:30 »
On a light quad there is more of a tendency to gain height on hitting the throttle, need some practice I think to master

I have been wondering if a switched in logic mix to feed in forward pitch with throttle and pitch settings above a certain level, allowing climb if not pitched forward into "speed" attitude would be beneficial.

Not usually one for mixes (I do not mix for knife edge on planes, etc, nor link rudder to aileron), but I have similar issue on the very high power 250 (which amounts to the same thing as a light quad, its very high power to weight ratio generated.

Its also where a few Sims cease to be real world, too, one's where you can throttle up at usual forward attitude with NO increased lift at all.

I feel a test coming on...................

Offline Cheredanine

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Re: Sub 250g racer
« Reply #50 on: August 18, 2017, 09:02:33 »
Whilst that does seem an excellent logical solution mate, it assumes a degree of consistency and accuracy of both ability and intent on the part of the pilot that is not there in a rate mode racer flying a meter above the ground on a twisting track. A lot of the time the initial throttle punch is in or exiting a turn where the incline is not only on the pitch axis but a non-consistent, and changing blend of pitch and roll, as such mixing pitch would have less effect on the height cline but would cause the quad to change direction in a way inconsistent with the stick input