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75% FT Goblin (strix nano goblin sized)

CapnBry

Well-known member
#22
Thanks for the tip! I pulled the motor off last night and really got in there with a flashlight and magnifying glass and it all looks intact in the motor. I flew today and it worked perfectly with no startup stuttering or unusual noises while running so I'm thinking maybe something was wrong in the blheli config and resetting fixed it. Shame these EMAX 12A ESCs can't be programmed through the 4way-interface (without modding them) so I could see the config before I reset it.

Flew 14 minutes on that 950mAh battery, although most of the time I was at 50-60% throttle. Charger put back in just under 800mAh, so that's an average of roughly 3.4A or 25-30W. Seems about right, although not as efficient as a STRIX Nano Goblin. This design has it beat on cost efficiency though, where the materials to build it cost about a dollar. ;)
 

CapnBry

Well-known member
#24
You should, this design is so great. It really zips around. I put a cheap AIO FPV camera in the nose and forgot to check the CG after mounting it, so I threw my little guy into the ground three times this morning trying to launch it. It didn't help that the foam was starting to come apart in the nose so I tried to wallpaper it with printer paper soaked in white glue to bring some strength back. That did give it strength but added soe weight I didn't compensate for. With the 3x5.2x3 propeller, you really gotta give it some throttle to launch or give it a pretty good heave due to the prop being almost completely stalled. Still managed to get it in the air but with 20kph steady winds I could head downrange REAL FAST and rock and roll my way slowly back into the wind.

It was too windy to try to fly between the trees, but the 75% Goblin does seem to skid through the corners more than the Mini Scout I took the camera off of. Most likely due to it going close to twice the speed. The unobstructed view from the nose is incredible though, I mean there's just no comparison!
PICT0007.AVI_snapshot_07.25_[2019.01.29_16.22.04].jpg PICT0009.AVI_snapshot_01.21_[2019.01.29_16.23.10].jpg
 
#29
I had posted this on the FB page yesterday and it there was quite a bit of interest. This isn't exactly a 75% FT Goblin. I made a few tweaks and changes to make it fit on a single sheet of foam. Builds pretty much the same as the FT goblin (or really any other FT plane). A few notes. I prefer to install the servos after the wing is slid in, but not glued in place. I added a small hatch on the bottom that can be opened to help with wire routing. Also I put marks on the spar as I cut the spares in half where the servos go after the spars in glued in but before I do the wing fold over. My intent was to build this to spec based on the
I had posted this on the FB page yesterday and it there was quite a bit of interest. This isn't exactly a 75% FT Goblin. I made a few tweaks and changes to make it fit on a single sheet of foam. Builds pretty much the same as the FT goblin (or really any other FT plane). A few notes. I prefer to install the servos after the wing is slid in, but not glued in place. I added a small hatch on the bottom that can be opened to help with wire routing. Also I put marks on the spar as I cut the spares in half where the servos go after the spars in glued in but before I do the wing fold over. My intent was to build this to spec based on the strix nano goblin. I have a 1407 3500kv motor on order and plan to build a 2s li ion pack from some cells. AUW of the strix is 250g ready to go. I weighted this with all my electronics sitting on it and it was just over 200g. I have not flown this but I have built. I have a local flying buddy who is going to try and fly the first one I built while I wait for my electronics. I would think up to an 1806 would work well with this plane on a smaller 3s lipo.

Justin
strix nano goblin. I have a 1407 3500kv motor on order and plan to build a 2s li ion pack from some cells. AUW of the strix is 250g ready to go. I weighted this with all my electronics sitting on it and it was just over 200g. I have not flown this but I have built. I have a local flying buddy who is going to try and fly the first one I built while I wait for my electronics. I would think up to an 1806 would work well with this plane on a smaller 3s lipo.

Justin
Thanks for scaling it down. Plans printed, poster boarded and the bird is stenciled on a fresh sheet of foam. Can't wait to start building her and flying or turning it into a dirt bullet...lol.
 

CapnBry

Well-known member
#30
And what sort of wattage are you pulling on it?
For what it is worth, my A pack with a 2-blade 5x3.5 pulls 7-8A on 3S (at 3.8V/cell) and generates 320g of thrust. On 2S it only pulls 4.5A and generates 190g of thrust (so worse than the 1407 3500KV on 2S with a 3x5.2x3).

eCalc's PropCalc says on the 1407 motor with a 5x3x3 you'd get 416g of thrust at 15A on 3S, and a 4x4x3 would get you 350g at 10A, all of which are ultraoverkill for a sub-200g teensy plane.
 

JennyC6

Well-known member
#31
For what it is worth, my A pack with a 2-blade 5x3.5 pulls 7-8A on 3S (at 3.8V/cell) and generates 320g of thrust. On 2S it only pulls 4.5A and generates 190g of thrust (so worse than the 1407 3500KV on 2S with a 3x5.2x3).

eCalc's PropCalc says on the 1407 motor with a 5x3x3 you'd get 416g of thrust at 15A on 3S, and a 4x4x3 would get you 350g at 10A, all of which are ultraoverkill for a sub-200g teensy plane.
Beautiful! A powerplant good for ~40 watts at full throttle oughtta fly this thing with authority then. I ask, mostly, because if/when I build one of these I'll be using a Cox 0.049 swinging a 5x3x3 Master Airscrew prop at somewhere around 17,000RPM, and that combo is good for somewhere around 40-50 watts.


Time to buy a box of FT foamboard and a few more cans of Rustoleum...
 

T-Richard

Active member
#32
Cut the plans and have all the electronics. Will run a rotorgeeks 1407 4000kv with a 3040 hq durable prop and an 18650 2500 25a on a 20amp esc. Using a TX 03 and I'll see if I can get the weight around 200 or bellow
 
#33
I have a Strix Nano Goblin, but I found it difficult to fit all the electronics in it. I was wondering if this build has more room in the canopy? Has anyone owned both?