FBL Gyro Spirit Pro with Three Bladed Goblin

Heliman450

Well-Known Member
Hi all,

I just finished building my wife's birthday present to me............... a Kyle Stacy Goblin 380. I fitted a Spirit Pro having already used one on my T-Rex 550.

I attempted my first test hover this morning only to find that it will be impossible to lift it from the ground without it destroying itself. Fortunately, I fitted my test gear so there was no damage to the heli.

This time, I used the setup wizard and chose 'Goblin 380'. I suspect that this is where my problem lies as the standard 380 is a 2-blade setup. Of course, the manual isn't of any help here as it's a kit, however, it does say something about a 3-bladed heli needing about 30% less gain than for 2-bladed.

Any help appreciated.
 

Smoggie

Well-Known Member
Great that you are adding more nice helis to the fleet!

I'd be pretty confident that the standard 2 blade defaults would work well enough to get you safely in the air. What exactly did it do?

Too high on the head gain would normally just result in some 'cyclic wobble', certainly nothing that should cause it to destroy itself. But if you do want to reduce head gain it's easy enough in the software or via the Tx integration interface (if you have that set up). But I'm thinking that the real cause of problems might be something more fundamental.
 

Heliman450

Well-Known Member
Hi Steve, I set the head gain to 40% rather than the default 55% that came up first off. Head wobble was exactly the way to describe it and I shut it down the moment it started to manifest itself thinking that it would be something more than just an adjustment. Of course, I can make the adjustment via my Jeti Tx. but I thought best to raise it here for some feedback.

I wanted to build myself a trailer for my bicycle to be able to fly when my wife's using the car but settled for her offer of a smaller heli that I can just carry on my back. I thought the Goblin was a good way to achieve it and also donate some of my hard-earned to my other local hobby shop.
 

Smoggie

Well-Known Member
If the wobble occurred during initial spool-up then the usual cause is that the main blade grips aren't tight enough and/or are uneven so that a blade is swinging back in the grip and un-balancing the head. You should be able to hold the heli on it's side without the blades pivoting down in their grips. To get them to fall should take a firm jerk of the heli.

Some ESC's suffer from an initial 'kick' on spoolup that can cause the blades to swing back.
 

Heliman450

Well-Known Member
Blades are nice and tight. The ESC is a Hobbywing V3 100A and spools up nice and steady. I'll back off on the gain a bit more for my next test and see how it goes................. photo below.

IMG_2409.JPG
 

Smoggie

Well-Known Member
She looks very nice Phil !

I've never experienced a situation where high head gain caused such dramatic problems but there's a first time for everything, and I've no experience of 3 blade heads. Good luck with the next test flight.
 

Heliman450

Well-Known Member
Hi Steve, the three blades was the main reason for me getting it so that I can gain the experience of the system.

It caused me a bit of a dilemma when checking it for CoG, in the end I took the head off and used to bolt hole to hang it up using an Allen key. The battery had to be set well back from what the manual showed. It's very front-heavy, so I've been doing a mod to the base plate to better fit the ESC, which is quite a bit bigger than what normally goes in. It was one of those bargains you just can't resist but it looks good now.

I'm hoping that the weather books up a bit to do another test tomorrow.
 

Smoggie

Well-Known Member
Phil, It really surprises me that it's nose heavy. I have the Devil 420 which is a clone of the Goblin 420, which in turn is just a slightly stretched 380.. That heli is quite tail heavy, i had to add lead in the front of the canopy to balance.

What battery are you using?.. Or maybe it's the big ESC that's causing the nose heaviness. I'm using a Hobbywing 60A which works fine.
 

Heliman450

Well-Known Member
I suppose very heavy is a relative term in a 380. Maybe it's better to say that the picture in the manual seemed to show the battery further forward than mine is and my ESC was sticking out the front so much that I needed to push the canopy a bit too hard for my liking to get the holes to match up with the screws. Both the battery and the ESC look much better now.

I'm using an 1800mAh OptiPOWER, which fits very nicely into the available space. I've used velcro fixings rather than the double-sided fixings that are supplied. This gives me the option to move the battery around on the tray. I had to file the slot and the tray to get a smooth fit as well as a properly functioning lock for the tray.
 

Smoggie

Well-Known Member
I have a 2200mAh battery in mine but the 420 does have a bit more disk area to carry a bigger battery. The canopy is a tight fit, mine is cracking where it pushes up against the front of the battery and wires. I cant move the battery back as I'm fighting tail heaviness at the best of times. I have got an 80A ESC that I intend to fit, not because the 60A isn't enough (it copes perfectly well) but mainly for the added nose weight.

I don't want any of this to sound negative because I actually really like this little heli, overall it's a great design and flies excellently.
 

Heliman450

Well-Known Member
Hi Steve, the way I see it, it's a kit so all the stuff that can give problems with CoG etc. are down to our choices about what the hang on it. I thought that everything was excellent, however, one small matter is shown in the attached photos. Mainly my own lack of attention, I must admit. I installed the skids the wrong way round :bellyroll:

The graphic in the manual shows the skids the wrong way round. The photos of the finished model show them correctly. I noticed too late and decided to lose the transfers as they finished up on the inside of the skid when fitted correctly. Here are the two images.....................

Skid Graphic_01.JPG

Skid Photo_01.JPG
 

Smoggie

Well-Known Member
Looks like they changed the shape of the skids but didn't get around to updating the manual. The manual is right insomuch that the short leg should go to the front, but the shape is all wrong.

It wasn't a problem for me because mine uses the 'flipper' type landing gear like used on the standard 380. I have flippers on my Goblin 700 Speed and on that big bird I don't like them much because the heli is quite unstable on the ground, but on the 420 they are fine. Given the choice I'd go for the more conventional full length skids like yours uses.
 

Heliman450

Well-Known Member
I thought the manual was extremely good when compared to all the others I've experienced so far but for the one small thing.

Going back a while, I watched a friend from the club flying his Goblin. I was so impressed how sweet it sounded I thought that one day I'd buy one. Now I have good reason to also own a small, high quality heli. So here goes for another stab at getting it into the air a bit later on today. Fingers crossed.
 

Heliman450

Well-Known Member
Up to now I haven't managed maiden #1, so this will be the second attempt to get it off the ground :bellyroll::bellyroll::bellyroll:

Right now I'm camera-less so my word will have to do. I think I've confessed enough about my failure on this one for you to trust me. I decided to go in the morning instead of the afternoon as the wind was a bit strong later on.

Bye for now.
 

Heliman450

Well-Known Member
Hi all, well..................... a mini-disaster as far as I'm concerned.

The heli spooled up nice and smoothly, lifted off the ground and promptly flipped right catching the main blade tips on the ground. I'm not sure what my next move is. Rather than risk smashing it to bits, I'm inclined to take it to Hugo where I bought it and ask him to check it over and tell me where I went wrong.

Any last minute suggestions welcome before I take it to him.
 

Smoggie

Well-Known Member
Sounds very much like reversed head gyro compensation, short of a servo suddenly failing there inst really anything else that would cause it. Gyro comp is easy to test and should be tested prior to every maiden. Just hold the heli level and quickly lean it right or left.. the swash must compensate in the opposite direction to the lean (i.e. the swash tries to stay level). If in any doubt just for testing increase the head gain all the way up so that the movement is more obvious. Also check compensation to nose up/down pitch in the same way. In addition double check response to stick input and make sure that's not reversed.
 

Heliman450

Well-Known Member
Hi Steve, I went through all the pre-flight checks as well as checking the servo responses during the initial programming of the gyro. I had to change over the servo wires between channels 1&2 to achieve the correct swashplate response.

As I've become more accomplished with the world of FBL gyros I ALWAYS check all the functions every time before attempting a test flight until I'm sure that the automatic responses are ok in flight. In addition, I also go through them if I haven't used the heli for a while and always after doing anything with firmware/software updates.

I've made an appointment with Hugo for Monday afternoon to brief him before he does the final checking. I intend to leave my transmitter as well just in case I missed something there.

I'll let you all know what comes out of his investigations.
 

Smoggie

Well-Known Member
Well it will be interesting to hear what Hugo finds but really i cant think of anything that on a new heli would be likley cause a tip-over so violently immediately after liftoff, other than reversed gyro compensation. A busted servo or extreme vibration levels are the other things that could cause it but on a brand new heli, not so likely.

It is quite easy to misinterpret the gyro response, especially when head gain is low. You need to really jerk the heli over very quickly, and the compensation can look like just a brief twitch, it's very easy to miss. A video might help... I just wish we were living closer so I could help first hand, 99% of the time it's something very simple.
 
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