Psyborgs Gremlin Build Setup and Review

LitterBug

Techno Nut
Moderator
Hey PsyBorg, What batteries are you flying with? I'd like to see some pics with your batteries attached and what AUW you are running in 2S and 3S fashion. I'm currently running 2/3 S Glacier 450mah on mine with JST connectors. The 800ma 2S was just too big but it still manages to haul it around despite being 50% of the weight. LOL

Cheers!
LitterBug
 

PsyBorg

Wake up! Time to fly!
hehe yeah I was running pregnant 800mah batteries when I first built mine. That with the fPV gear came in at 187 g.

This was the first good flight on it with the 800's


Here are the ones I use now.

Grembats.jpg

with 2s (no vtx or camera)

Gremweight2s.jpg

With 3s (no vtx or camera)

Gremweight3s.jpg

Under slung battery

Batstrap.jpg
 

PsyBorg

Wake up! Time to fly!
Was such a beautiful sunny day here with gentle breezes so I took the Gremlin out for some filming to show what the new settings do on 2s and 3s now. Even the yard monkey was out making my field pretty again. The changes I made to the rates helped a lot with over shooting hard turns and flips due to the Gremlins short wheelbase. (yes I know it does not have wheels :eek: )

The retuning has taken a lot of that motor grinding noise that came about on my old tune after the swap to a stiffer carbon frame. The only thing left to do now is figure out Beta Flights TPA range better so I can get rid of the upper throttle shakes on 3s. I am not sure but it feels like it is actually faster now on the 3s when I can do a full speed run before it gets out of my sight range in LOS.

Anyways here is an edit I chopped down from over 11 minutes of footage from a session with only a single 2s and 3s battery.


And here is the settings it was running.

Grempids101717_2.jpg
 

PsyBorg

Wake up! Time to fly!
Finally got a good FPV set up going on this. :applause:

Using a Runcam Swift 2 micro with osd and an Eachine ATX03 VTX. I have some tweaks to do on the tune again with the weight change and I want to Widen my rates to get more of an expo feel without actually using expo. I will post screenies of it all once I have it worked out.

Was out this morning testing and setting it up as well as trying new Pulse 3s 450 mah 45c batteries.

 

PsyBorg

Wake up! Time to fly!
Yes I am much happier now. Shame the weather is gonna be wet n crappy next few days as this just arrived a half n hour ago and I been puttin the gates together and checkin it out. I MAY have to clean up the living room and kitchen and do some runs inside hehe.

This kit is seriously worth the price. All kindsa stuff for less then the price of one flag for full size race quads.

https://www.amazon.com/Premier-RC-Micro-Advanced-Racing/dp/B06WWBXVTG/ref=sr_1_1?ie=UTF8&qid=1509223785&sr=8-1&keywords=Race+gates
 

PsyBorg

Wake up! Time to fly!
More progress on the Gremlin for a race setup now. Rains finally took a short break this afternoon so I got out for some test runs using the new gates. Was still a tad windy so that was good. Found out I needed to boost D gains nearly double what I started with to hopefully counter the slushy feel when there is wind pushing. I gains seem fine as it doesn't drift in hover very much. The last part of this video seemed way more locked in. Having a better camera angle for low gate runs will help too. I hate 2.3 lens but cant find a 2.5 for the runcam micros yet.


 

PsyBorg

Wake up! Time to fly!
Yeah slowly gettin it dialed in. Hittin them tiny gates is tough tho. Between no torque on them tiny motors and high grass its hard staying that low to hit them when the props stop if too may grass strikes. Getting a tighter tune will help where I only have to concentrate on staying low as when I line up now I should stay on one line and not over correct or move from cross winds as much. I may have to mess with a throttle curve so I get a bit more lift or feeling of lift in the very low throttle range to pass under them gates. They are meant more for tiny whoops then Gremlins ripping thru them.

I think the small gate in the grass leaves an opening about 6-8 inches tall at best. When half of that height is taken by the normal quad tilt in forward flight that leave little room for error. I will get better though for sure running them. Hoping that all translates to better targeting with the big boys. But a 5 ft square hole looks like a truck stop compared to these little things.
 

PsyBorg

Wake up! Time to fly!
Worked some more on the tune. I am now 100% against the statement quads fly fine on stock pids in Beta Flight. I will leave it at "Quads fly on stock pids".

When it comes to the Gremlin it is actually harder to get it to fly accurately then the larger quads. I am finding this out more and more now that I am getting used to a different lens then I normally fly with. To hit gates sized for the Gremlin and be controlled its is harder as you as constantly flying in ground effect. This requires a completely different approach then flying fast above 3 feet or doing freestyle with them.

The level of precision with throttle management is exponentially more important then any other quads I have flown. There is a seriously minuscule range where you go from low flight to tumbling. Its almost like the throttle calibration will not allow for such a precise low stick set up. Its like a 10-20 us range where you either pass under the gate or you tumble thru it with this tiny thing. I also think a lot has to do with the props requiring the torque to keep spinning at low rpm on motors that are made for higher rpm efficiency.

I do think it is able to be set reliably but it is surely tasking me to think different on how to do it. The next thing on my list is to try some reverse expo on the throttle to stiffen the stick control on the extreme low end.

Anyway here is the latest testing run with what I have worked out for my set up.

 

PsyBorg

Wake up! Time to fly!
The Key hole gates are 17 inch dia and 14.5 inch dia and the normal gates are 12 inch tall by 17 wide inside radius and 11 tall by 14 wide radius. Then you have to guess how low they sit in the grass AND how high the grass around it is. Ours has not been mowed in several weeks and is pretty tall so when I was doing the track practice I have grass hitting blades and stalling props as I was trying to go thru them on top of a weak tune allowing a lot of drift with the breezes. Enough to make me wanna pull my hair out. (If I had any)

The Gremlin is 5.5 inches at the widest measurement of the props and 5 inches at its length. Doesn't leave much room for error when zippin around on 3s hehe. I guess over time I will get REALLY accurate at hitting small holes once I get it tuned perfectly.
 

ElectriSean

Eternal Student
Mentor
Worked some more on the tune. I am now 100% against the statement quads fly fine on stock pids in Beta Flight. I will leave it at "Quads fly on stock pids".

Larger quads fly amazing on defaults, micro's not so much...

The level of precision with throttle management is exponentially more important then any other quads I have flown. There is a seriously minuscule range where you go from low flight to tumbling.

One way to increase that range is to fly faster, you just need to line it up more in advance and blast through :D Easy to say, I know lol.
 

PsyBorg

Wake up! Time to fly!
From what I have learned using beta flight the range where the quad will fly is vast. Old school set ups you had 1 or 2 point variance or 10- 20 points depending on what the software scaled to to dial in the quad. On Beta Flight you can range from 30 to 80 on any settings and fly. I find the defaults for most X or stretch X quads to be loose and sloppy. This translates to hot motors and a very floaty flight. You can easily tell in videos who is flying stock pids and who has at least tried to tune better. Stock pids fly like a pendulum and tend to turn lazily with a lot of drift and over steer. The will get a new pilot in the air for sure but I think the better performance for stock settings comes more so from better rates over the old defaults then the pids.
 

PsyBorg

Wake up! Time to fly!
Speaking of pid tuning... rates too. This is the progress made on the last round of changes. This makes twelve packs flown and three changes since the video system went back on. I had to repair a broken wire that got ripped off the XT 30 in the last crash of the day yesterday. I changed the wire lengths and zip tied it to the frame. Now it supports the battery cables much better which also helped the stability I think.

The Pulse batteries have some serious wire to the connectors and so far I am loving these. Time will tell how well they hold up as I grabbed one that was just on storage charge and ripped it down to below 7v before it went all low power cut off without the cut off. I am hoping it recovers well enough to take a charge.

Anyway here is the new craptastical edit on one of the longer runs I had pulled off. You will really get an idea how high the grass is and how low I have to be to get thru these gates in it.


I think some fine tuning is next as I went too far on roll P I think and I want to raise the brightness of the camera a touch as well as I had to push it up a bit in post to show how nicely the day / night settings and color levels are on a bright sunny late afternoon.
 

PsyBorg

Wake up! Time to fly!
<<<< haz yard monkeys for that.. (property management maintenance man) They are hibernating it seems. In their defense there has been tons of rain the last two weeks so cutting anything was a not gonna happen.