75% FT Goblin (strix nano goblin sized)

[Ironhaigen]

Ok I’ve cut and assembled a new build. Upon careful consideration, I realized Id made a noob mistake.

I had my elevons reversed on the pitch axis. Doh. The nosediving makes more sense now.

Gonna go charge and maiden and hope for the best.

 

[BorisTheSpider]

Ok I’ve cut and assembled a new build. Upon careful consideration, I realized Id made a noob mistake.

I had my elevons reversed on the pitch axis. Doh. The nosediving makes more sense now.

Gonna go charge and maiden and hope for the best.

How did it go with the controls set up right?

 

[BorisTheSpider]

I wonder how well the power pack H would work on this as a twin engine set up,...

I don't have the H power pack but I did set one up as a twin with some tiny motors Off-hand, I'm thinking they were 13xx. It flew beautifully. It could be docile or a speed machine and super nimble to boot. It looked great as it plowed into that tree. . .

 

[swedak]

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

I have used your great plan for STEM education materials. Thank you so much.
Also, I would like to make a prototype of a small VTOL under 250g based on this plan for education so learn both rotor copters and fixed wing aircrafts(see a link to ardupilot forum). And I would like to present this plan of yours at a conference, can I introduce and publish the plan here?
https://discuss.ardupilot.org/t/copter-tailsitters/45514/859

 

[TheOrangeBaron]

Here are tiled plans for a standard US letter paper. Just cut along the small lines along with each page, tape it together and it becomes a seamless 20x30 scaled plan!

Note: for printing settings.... print at full size, NOT fit to printable area. Yes, the squares in the corners will get cut off but the small dash indicating the cut line will still be visible, just use a straight edge and razor to trim down each page and you should be good to go.

 

[kevinjaako]

@CapnBry, since you brought up efficiency...

Do y'all think it's possible to get a scratch-built Goblin as efficient as the Nano Goblin? I'm talking about 45-min flights on Li Ion... think it's doable? Obviously scratch-built isn't as streamlined as the Strix NG, but it doesn't seem that much chunkier... What do you think?

 

[SSgt Duramax]

@CapnBry, since you brought up efficiency...

Do y'all think it's possible to get a scratch-built Goblin as efficient as the Nano Goblin? I'm talking about 45-min flights on Li Ion... think it's doable? Obviously scratch-built isn't as streamlined as the Strix NG, but it doesn't seem that much chunkier... What do you think?

I think it is possible. I am making a smooth winged goblin now. You could also experiment with cutting the v stab and wings down to reduce drag. I did the opposite approach though, I scaled it to 130% (ends up with a 1m wing span) so Ill have more room to mess around and experiment. I am also working on designing a high loiter time drone type thing, I have a prototype but havent flown it yet. Should be an exciting weekend for maidens! I am nearly done with my goblin too!

 

[CapnBry]

@CapnBry, since you brought up efficiency...

Do y'all think it's possible to get a scratch-built Goblin as efficient as the Nano Goblin? I'm talking about 45-min flights on Li Ion... think it's doable? Obviously scratch-built isn't as streamlined as the Strix NG, but it doesn't seem that much chunkier... What do you think?

Eeee I think it would be tough to get that much out of it. I've revised my build several times and ended up with the Goblin 86 (<- link), which has a thinner wing, no undercambered tips, smaller fins, and a thinner fuselage profile. It does 0.6Wh/km cruising at 50kph (around 80mAh/km for 2S). Those numbers will get you ~45mins on 3000mAh, but I think the battery is going to get too low to keep it up that long.

The airfoil on the real Nano Goblin is just so thin and the fuselage is just the perfect shape. I do not know how they squeeze so much performance out of it, because it still seems to be unattainable through all of my tweaks and experiments with the DTFB design. The Goblin 86 is a fantastic medium cruiser with a 1300mAh 2S though. If you strip out all the FPV gear and flight controller and get it as barebones as possible, maybe it would get close?

 

[SSgt Duramax]

Eeee I think it would be tough to get that much out of it. I've revised my build several times and ended up with the Goblin 86 (<- link), which has a thinner wing, no undercambered tips, smaller fins, and a thinner fuselage profile. It does 0.6Wh/km cruising at 50kph (around 80mAh/km for 2S). Those numbers will get you ~45mins on 3000mAh, but I think the battery is going to get too low to keep it up that long.

The airfoil on the real Nano Goblin is just so thin and the fuselage is just the perfect shape. I do not know how they squeeze so much performance out of it, because it still seems to be unattainable through all of my tweaks and experiments with the DTFB design. The Goblin 86 is a fantastic medium cruiser with a 1300mAh 2S though. If you strip out all the FPV gear and flight controller and get it as barebones as possible, maybe it would get close?

That's just it. A lot of the planes we love that are very efficient get that way by being slippery. My wing that hangs in the air for 20 minutes on a 2200 MAH will cover a ton of ground fast. Like at 50% throttle you are travelling speeds that a decent bit of folks consider "fast" and it is kind of heavy and gives up some low speed stability. I think it would be pretty hard to have a "high lift slow flyer" and at the same time have an efficient plane. I am trying something similar and you can only get so far with a box. Reducing the frontal area is a start, but it isn't all of it. That is why those nice little formed EPP planes can be more efficient.

 

[TheOrangeBaron]

Just finished building mine today. Can't wait for the maiden. It all fit well on one piece of foam board, using my tiled planes derived from the original post plans. The wing tips of mine were a little too thick to fit thru the fuselage, so I had to carve off some more of the fuselage airfoil cutout. Followed the flight test FT goblin tutorial for the wing, and was slightly confused on the fuselage, but I figured it out. Went together relatively smoothly and was fun to build. I put a little AIO eachine txo5 camera in the nose, powered off the onboard BEC.

I used a 1806 2400kv motor that was like 5$ on aliexpress. I paired it with a 5040, but I also have a 5030 and 5045 bullnose to experiment with. I also have a 3s 850, 2s 1000, and 2s 800 to experiment with. All up weight EXCLUDING battery is 200 grams, 247 if you include the 2s 800. I used some cheap 9g servos, 3d printed control horns, 3d printed motor mount, and irrigation marker flags as the pushrods. Used a super overkill but lightweight blheli 30amp esc paired with a 5v 3a BEC(this combo was lighter than all my other ESC w/bec combos I had laying around). I also added some packing tape to the belly of the fuselage. I taped up the leading edge, before folding the wing over, to give it more durability, and water resistance.

With the 5040 running 2s, I am able to get 255 grams of thrust, pulling 7.4 amps, but I believe it can cruise with a conservative 3 amps. This would give it around 11 minutes of safe flying time with the 2s 800, and if you put a 2s LiIon battery in, possibly up to 40 amps. These are all just calculations, given my testing, and I hope to have an update soon with real flying data.

 

[TheOrangeBaron]

Maiden was today. Crashed first two launches due to low thrust on 2s. On 2s, the thrust to weight ratio is less than 1, not optimal for my taste. Around 60% throttle to cruise at 2s, 45% to cruise at 3s. The 3s 850 seemed to fit the plane perfectly, with a good amount of punch, and a decent 11 min flight time for such a cheap battery. The 1806 2400kv motor seems to be too slow, I am in the process of getting some 1507 4000+kv motors, that hopefully will increase my thrust weight ratio and make the plane slightly lighter. I made a short video on my maiden, it consists of onboard dvr footage.

After flight images posted below, it looks great considering I flew it head first into a metal shipping container!

 

[ronis]

Just maidened.
Made as CapnBry Goblin86 (Goblin86 Long Range / Cruiser | FliteTest Forum)
Winds was quite strong and freezing, but everything went very smooth. After 15 minutes my fingers become too stiff. Now waiting for next session and, probably, better weather. Like it very much. My first foamboard plane BTW.
Thank you guys for creating and sharing.

* ZMR 1804 2300kv
* Gemfan Apc Nylon 5x5 prop
* 10 Amp ESC, RCX (probably, found in box)
* EMAX 4.3g servos
* Lefei Sparrow 2-OSD
* CADDX ANT
* Eachine TX805
* 3s 1Ah
AUW 318g

 

[XSrcing]

How many mah did you use in that frozen 10 minutes?

 

[ronis]

How many mah did you use in that frozen 10 minutes?

Will look in records later
As I remember it was 10.4V at the end ~15minutes.
Will report later
Weather was -5C, wind ~6m/s, gusts ~9m/s ground level, higher - more

 

[ronis]

12 minutes nonstop flying - 578mAh 11.4V static, 11.0V at 3.3A
then some landings launches
at the end of session - 18minutes - 675mAh 11.2v static, 10.6 at 4A "total" distance - 9.9km, but not reliable because of winds.
THR 70% and climbing - 7A
THR 62% - 5.4A
THR 97% up to 10.2A
for cruising at THR 50% ~4A
sorry, no speeds due to gusty and strong wind

 

[Jonny360]

Did you guys need to open up the wing slots in the fuselage? I used the spar doubled over and my wing came out about a foamcore width too thick to fit in the holes in the fuselage. Is the wing supposed to be a single layer of spar? Or do I need to cut the holes bigger?

 

[ronis]

Did you guys need to open up the wing slots in the fuselage? I used the spar doubled over and my wing came out about a foamcore width too thick to fit in the holes in the fuselage. Is the wing supposed to be a single layer of spar? Or do I need to cut the holes bigger?

Seems hole have to be be cut bigger.
For this design there are two layers of foam in wings. I have Goblin86 (Goblin86 Long Range / Cruiser | FliteTest Forum ) and there is only one layer of foam in wing and fits tight, but quite nice in the wing slot.
Sorry, can not say anything more constructive

 

[Mitchmoo5000]

Thanks to the creator of this thread for the great modifications to the goblin. I modified your modified plans lol! I’ll be using two 1404 motors and running a 3s 550 battery.My goal is to be able to add fpv and stay under 250 grams. Here's a link to an article and plans! https://forum.flitetest.com/index.p...IV2Ky70_t89ZkzsnyB4oam4QbLVf731b2IZ5W5fC5sf6Q

 

[nathanjohnson83]

so I know this forum is a bit old, but I have a quick question. I grew up building with balsa kits with my dad and as an adult I'm getting into foam building. This is my first build and I'm learning a lot about how fun foam board can be. As I looked over the plans for this I cut everything out, but I'm not sure what the parts marked I and II are for as well as the triangular piece top middle. Everything else feels self-explanitory. Thanks!

 

[sirjaymz]

so I know this forum is a bit old, but I have a quick question. I grew up building with balsa kits with my dad and as an adult I'm getting into foam building. This is my first build and I'm learning a lot about how fun foam board can be. As I looked over the plans for this I cut everything out, but I'm not sure what the parts marked I and II are for as well as the triangular piece top middle. Everything else feels self-explanitory. Thanks!

The Triangle is the 'Drafting Triangle', as called out in the instructions for the Tiny Trainer. It's used to ensure you are installing the rear rudder 'wings' vertically with respect to the fuselage.

The items marked 'I' and 'II' are to ensure that you have the wing rake folded to the correct angle. This is used to ensure the proper folding 'degrees' are achieved with a quick 'go-by'.

Quite honestly, I don't use either of these items, and use a carpenters speeds square for the vertical wings, and as far as the rake of the wing, I use the flat surfaced and the folds of the wing to achieve the angle that's 'good enough'.