So I've been hinting a new heli purchase the last few weeks. I wanted to do the build thread post on it in one fell swoop and I just finished building it, so here it is:
Goblin 500!
I picked up a combo kit that included the motor and servos (the new BK mini HV servos) back when they were on pre-sale at Helidirect. With the wedding and work and all I wasn't able to get the time to build it. I'm married now and work has calmed a bit, thankfully, so had some late night time to put into building this beauty.
No unboxing here, there's plenty of that on the net already. These are my in-build photos and comments.
Frame and skid assembly were pretty simple. Sanded down all the outside and most of the inside edges of the frame halves (left the "G"s alone). Skids attach in an interesting way, the two plastic skid holders slide in a channel along the bottom of the frame and stop at either end. The carbon skids themselves are designed to break off in the event of a crash, presumably leaving these plastic skid attachment points in place. Not sure how well it will actually pan out. Hope I never find out.
Batteries are mounted to plates which slide in and lock via this side latch. The latch is just a metal piece stuck on a partially cut out piece of the frame half. The spring tension is provided by the carbon frame material. Need to be careful not to yank on this too much or you will break it. In the event it does break, you can mount the metal piece to the other side, I think.
The much heralded goblin transmission, just in smaller form. Went together pretty easy. Shimming was a little laborious, but it is locked in great and solid as a rock. Gear mesh will take a flight or two to wear in fully (small high spot on the black gear) but otherwise all good. OWB is in the pulley assembly to the lower right. Neat design. Whole thing kind of smacks of over engineering, but its cool.
The one unboxing in the build thread, the motor. Ooooo what's inside?
The red velvetish material was a nice touch. Good presentation.
The motor mounted up on the heat sink plate and the pulley installed.
Head came partially assembled. I took it apart to inspect and re-LT everything. I like the design here. The holes in the blade grips through which you would screw in the arm (seen on the left grip's cylinder face) acts as a lubrication access point too so you do not need to pull it all apart to do some lubing. There is also a hole in the top of the hub through which you can put some lube if needed (can't imagine it would be very often, if at all). Also the blade links are turnbuckle style for precise tracking adjustments, nice.
Tail assembly was similar. It actually has a flapping head design with a spindle, just like the main blade head. The link angle here looks odd but it is how it should be from what I understood from the manual and online research. The acute angle made adjusting screw tension and getting things loose difficult compared to other tail setups I've worked on. I'll be keeping an eye on this to see how it wears in and making sure nothing backs out.
Tail case is skeletal compared to ones I've worked on before (550x, 300x, TRex 700). I'm not a fan of the tail stab being an integral part of the case. I have a habit of having to replace these either through mistake transporting the heli or due to crashes. I worry that a crash with this will result in the whole tail case potentially becoming unstable and resulting in a far worse crash scenario and repair bill than normal. That all said, I like the belt driven system on this heli. Big pulley in the back makes for a very smooth transfer of power with little chance of belt jumping being a serious problem.
Transmission installed, tail servo installed, starting to look like something now!
My least favorite part of heli building (next to cleaning up electrical routing), servo setup. And in this heli it is worse than normal because you need to make sure you have the plates on in the correct orientation and on the necessary side of the servo mounting tabs, etc. There are specific mounting depths the ball centers should be from the mounting surface of the carbon plates in order to get the swash link geometry right. Also had to trim off three of the arms from the four sided horns, after finding the most centered tab (which meant getting the ikon and a power source setup to get them powered up and centered at reference position). Tedious.
Trimmed and mounted tail servo horn. This servo mounting location requires a full side servo, not the mini size of the cyclics. The BK tail servo for this setup comes with a full size mounting plate out of the box despite it being a mini size otherwise. I like it.
Cyclics all mounted up. Wiring is going to be odd on this one due to the unconventional mounting configuration, made even worse by the form fitting canopy (more on that below).
Swash and head installed.
Motor mounted up and drive belt tensioned. Wires secured. Note I opted to go with a rpm sensor instead of using the one build into the Edge ESC. In truth I forgot that the ESC had this available or else I would have used it.
Start of some wiring down below. Opted to go with a CC BEC Pro instead of an Rx pack since I've been using the same setup on my 700E and the 550x also has a BEC. Servo are HV so I'm running 7.6V I think out of the BEC Pro. Fed by 6S I think it will be able to source something like 14A of power, which should be way more than adequate. I make a mistake here in running the lines from the ESC battery taps to the BEC source on the bottom of the frame. The canopy fits very tight down here so I ended up having to undo the ESC and move that wire inside the frame along the side of the ESC. It is better that way anyway, but it was annoying to have to redo. I also need to get a longer set of zip ties. I was using two to wrap and secure either end of the ESC and that results in link end being on the bottom of the frame near the skid strut, which is a no go with the canopy fit.
Oy, what a mess of wires.
Rats nest.
Tail all mounted up.
Had to glue some of the wires to the edge of the frame.
Yeah, this is gonna be fun.
Managed to get it sorted out. I ended up putting the FBL mounting plate on backwards from what was said in the manual. It seems solid enough this way and it gave me more room to get the FBL away from the wall created by the anti-rotation bracket. As it is, it is still a bit too close for my liking. The wires going into the FBL are a bit too compressed which can transmit vibrations and cause issues. I did my best to keep things secure but loose enough to hopefully minimize that effect. Also, ran into another canopy issue at this stage. The fit around the cyclic servos is very tight. You can see in these pics where I bundled up some wires under one of the servos. I had to redo that with the wires routed and secured as flat as possible against the back of the servo instead. Underneath they were bunched up too much and the canopy was getting stuck a bit on them.
And done! The head and balde grips have some hash marks on the top that aid quite a bit in setting up zero and max/min pitch. After leveling the swash (done before mounting the head assembly) and using the hash marks to get blade grips to zero... I didn't actually use a blade angle gauge at all. I'll do a quick check tomorrow when I hope to do the first spin up and test flight with it, but I'm pretty confident things will be good to go.
A note on the canopy: It is stupid tight. I had trouble getting the canopy screws to go in, even after it was fully mounted on the heli. And I do not like the stock mounting thumbscrews. The threading is very finicky and difficult to get started without cross threading them. I plan to pick up a set of Booya's or something else like that with a simple push button ball bearing locking scheme.
Air flow inside this thing is going to be minimal. I may end up expanding the vent holes on the top and bottom front (one for top edge of motor and one for ESC) to let more through. BEC mounted on the bottom should hopefully be okay. Lastly, I may pick up a CC inline auto-connector for a castle link. Having to unplug from the back of the FBL to hook up the computer to read out logs and whatnot is going to be tedious.
So, hopefully get it in the air tomorrow. Will video it and get it posted.
Goblin 500!
I picked up a combo kit that included the motor and servos (the new BK mini HV servos) back when they were on pre-sale at Helidirect. With the wedding and work and all I wasn't able to get the time to build it. I'm married now and work has calmed a bit, thankfully, so had some late night time to put into building this beauty.
No unboxing here, there's plenty of that on the net already. These are my in-build photos and comments.
Frame and skid assembly were pretty simple. Sanded down all the outside and most of the inside edges of the frame halves (left the "G"s alone). Skids attach in an interesting way, the two plastic skid holders slide in a channel along the bottom of the frame and stop at either end. The carbon skids themselves are designed to break off in the event of a crash, presumably leaving these plastic skid attachment points in place. Not sure how well it will actually pan out. Hope I never find out.
Batteries are mounted to plates which slide in and lock via this side latch. The latch is just a metal piece stuck on a partially cut out piece of the frame half. The spring tension is provided by the carbon frame material. Need to be careful not to yank on this too much or you will break it. In the event it does break, you can mount the metal piece to the other side, I think.
The much heralded goblin transmission, just in smaller form. Went together pretty easy. Shimming was a little laborious, but it is locked in great and solid as a rock. Gear mesh will take a flight or two to wear in fully (small high spot on the black gear) but otherwise all good. OWB is in the pulley assembly to the lower right. Neat design. Whole thing kind of smacks of over engineering, but its cool.
The one unboxing in the build thread, the motor. Ooooo what's inside?
The red velvetish material was a nice touch. Good presentation.
The motor mounted up on the heat sink plate and the pulley installed.
Head came partially assembled. I took it apart to inspect and re-LT everything. I like the design here. The holes in the blade grips through which you would screw in the arm (seen on the left grip's cylinder face) acts as a lubrication access point too so you do not need to pull it all apart to do some lubing. There is also a hole in the top of the hub through which you can put some lube if needed (can't imagine it would be very often, if at all). Also the blade links are turnbuckle style for precise tracking adjustments, nice.
Tail assembly was similar. It actually has a flapping head design with a spindle, just like the main blade head. The link angle here looks odd but it is how it should be from what I understood from the manual and online research. The acute angle made adjusting screw tension and getting things loose difficult compared to other tail setups I've worked on. I'll be keeping an eye on this to see how it wears in and making sure nothing backs out.
Tail case is skeletal compared to ones I've worked on before (550x, 300x, TRex 700). I'm not a fan of the tail stab being an integral part of the case. I have a habit of having to replace these either through mistake transporting the heli or due to crashes. I worry that a crash with this will result in the whole tail case potentially becoming unstable and resulting in a far worse crash scenario and repair bill than normal. That all said, I like the belt driven system on this heli. Big pulley in the back makes for a very smooth transfer of power with little chance of belt jumping being a serious problem.
Transmission installed, tail servo installed, starting to look like something now!
My least favorite part of heli building (next to cleaning up electrical routing), servo setup. And in this heli it is worse than normal because you need to make sure you have the plates on in the correct orientation and on the necessary side of the servo mounting tabs, etc. There are specific mounting depths the ball centers should be from the mounting surface of the carbon plates in order to get the swash link geometry right. Also had to trim off three of the arms from the four sided horns, after finding the most centered tab (which meant getting the ikon and a power source setup to get them powered up and centered at reference position). Tedious.
Trimmed and mounted tail servo horn. This servo mounting location requires a full side servo, not the mini size of the cyclics. The BK tail servo for this setup comes with a full size mounting plate out of the box despite it being a mini size otherwise. I like it.
Cyclics all mounted up. Wiring is going to be odd on this one due to the unconventional mounting configuration, made even worse by the form fitting canopy (more on that below).
Swash and head installed.
Motor mounted up and drive belt tensioned. Wires secured. Note I opted to go with a rpm sensor instead of using the one build into the Edge ESC. In truth I forgot that the ESC had this available or else I would have used it.
Start of some wiring down below. Opted to go with a CC BEC Pro instead of an Rx pack since I've been using the same setup on my 700E and the 550x also has a BEC. Servo are HV so I'm running 7.6V I think out of the BEC Pro. Fed by 6S I think it will be able to source something like 14A of power, which should be way more than adequate. I make a mistake here in running the lines from the ESC battery taps to the BEC source on the bottom of the frame. The canopy fits very tight down here so I ended up having to undo the ESC and move that wire inside the frame along the side of the ESC. It is better that way anyway, but it was annoying to have to redo. I also need to get a longer set of zip ties. I was using two to wrap and secure either end of the ESC and that results in link end being on the bottom of the frame near the skid strut, which is a no go with the canopy fit.
Oy, what a mess of wires.
Rats nest.
Tail all mounted up.
Had to glue some of the wires to the edge of the frame.
Yeah, this is gonna be fun.
Managed to get it sorted out. I ended up putting the FBL mounting plate on backwards from what was said in the manual. It seems solid enough this way and it gave me more room to get the FBL away from the wall created by the anti-rotation bracket. As it is, it is still a bit too close for my liking. The wires going into the FBL are a bit too compressed which can transmit vibrations and cause issues. I did my best to keep things secure but loose enough to hopefully minimize that effect. Also, ran into another canopy issue at this stage. The fit around the cyclic servos is very tight. You can see in these pics where I bundled up some wires under one of the servos. I had to redo that with the wires routed and secured as flat as possible against the back of the servo instead. Underneath they were bunched up too much and the canopy was getting stuck a bit on them.
And done! The head and balde grips have some hash marks on the top that aid quite a bit in setting up zero and max/min pitch. After leveling the swash (done before mounting the head assembly) and using the hash marks to get blade grips to zero... I didn't actually use a blade angle gauge at all. I'll do a quick check tomorrow when I hope to do the first spin up and test flight with it, but I'm pretty confident things will be good to go.
A note on the canopy: It is stupid tight. I had trouble getting the canopy screws to go in, even after it was fully mounted on the heli. And I do not like the stock mounting thumbscrews. The threading is very finicky and difficult to get started without cross threading them. I plan to pick up a set of Booya's or something else like that with a simple push button ball bearing locking scheme.
Air flow inside this thing is going to be minimal. I may end up expanding the vent holes on the top and bottom front (one for top edge of motor and one for ESC) to let more through. BEC mounted on the bottom should hopefully be okay. Lastly, I may pick up a CC inline auto-connector for a castle link. Having to unplug from the back of the FBL to hook up the computer to read out logs and whatnot is going to be tedious.
So, hopefully get it in the air tomorrow. Will video it and get it posted.
