General T-rex 800 Battery Connection.

[Smoggie]

Sorted, without having to go the SRXL route.

Personally i'd still go SRXL, it's just neater with only one wire.

You will also need to use the USB link to setup the ESC governor, if going that route. Governor (either ESC or FBL) is highly recommended on a big heli.

 

[Tony Mitchell]

Yep, I will be going down that route eventually. I just wanted to get it all checked out with what I've got in the kit first off. The Rx only came with the one remote, I want to add the other two to give me good Rx visibility as there's a heck of a lot of carbon and metal on this.
Just had to check it out...

 

[D.O.G.]

That's such a sweet bird you have there . Welcome to the forum and good luck with your first flight Love to see a video and hear that bird in action

 

[Smoggie]

Awesome! I bet it was a bit scary when it first spooled up!

PS.. you dont need anything 'extra' to run governor mode. The ESC has the facility to do it, you just need to program it to turn it on. The Microbeast has governor function too though i'm not sure if you need to buy a software upgrade to enable it or not?

Good luck when it comes to the maiden flight, looks like you are nearly there.

 

[Tony Mitchell]

Looks like I've got a long wait before I can get it out to our club flying field. I'm tempted to get it into hover, just to get it fine trimmed, but it's so noisy when it spools up. Just about as noisy as the real thing.
Thanks for the welcome D.O.G. I'll get all my little birds lined up tomorrow if it's decent weather, take a pic and put it up in the newbie section as I haven't posted in there yet.

 

[Smoggie]

Looks like I've got a long wait before I can get it out to our club flying field.

I feel your pain. Luckily I have some waste ground not far from home. I rarely see another person there so I can sneak out and get a few flights in. If challenged by the 'Boys in Blue' I could always claim that I'm out for
exercise, specifically a good workout of my thumbs

 

[Tony Mitchell]

Risky. Before they imposed the lockdown, I took my 500 and 470 onto what is left of the eastern end of the old runway near to Rolls Royce. At the moment, it's just wasteland. No idea what they have planned for that bit. I've seen a couple of people walk dogs through it when I've been walking on the public side of the fence, but none when I've flown there. This bird is a different story though. It weighs in at 14lb with batteries in and it's quite a walk from where I would have to leave the car. Add to that, I have to drag the Mrs out to accompany me with first aid kit etc. Can't go flying solo with one of these.
It's the back garden for the 500, 470 and 450 til the lockdown is over. I've got space here to hover and fly small circuits at about 1.5metres altitude. On the other hand, I can fly my Blade Nano S2 around the house.

 

[Smoggie]

I fly by my own quite a lot, even in 'normal' times. similar size helis to your new Trex. I honestly dont think the risks are unmanageable, just keep the heli at a safe distance and it cant hurt you. Much safer than other hobbies I've indulged in over the years.

Here's my last 'lockdown busting' outing this last weekend, Goblin speed 700 and a Henseleit TDR2. The TDR2 is an 800 size heli biut it's running 760mm blades at the moment, 14S power .

Big helis are so much easier to fly it's almost like cheating. Flying a micro actually stresses me out much more!

 

[Tony Mitchell]

Nice birds, I wonder how they handle compared by the T-Rex range.
My long term project for the 800 though, is a scale fuselage. I'm working on plans to create a scale Chinook along with all the challenges that presents.

 

[Smoggie]

Nice birds, I wonder how they handle compared by the T-Rex range.
My long term project for the 800 though, is a scale fuselage. I'm working on plans to create a scale Chinook along with all the challenges that presents.

I've got a lot of different brands of heli. Overall I find that the setup makes probably more difference than the actual model/brand. You will be the same with yours, by tweaking setup you can have whatever you want from mild scale flying characteristics to wild hardcore 3D.

The Chinook will be a real engineering challenge. there used to be kits available but I think they are long gone. Some current FBL controllers do have the facility to support tandem rotor mixing, so that part of it should be reasonably straightforward. One thing that makes it more complex is that you cant have the the two rotors driven independently by two motors (because the rotors inter-mesh). So you need to make them connected together by a drive shaft or belt. Very interesting project for sure.

 

[Tony Mitchell]

I'm thinking of a new motor mount that will hold two motors, both driving the same main gear. Have a gear linkage similar to (but stronger than) the tail rotor drive shaft, between the two main gear wheels. That should give the power to drive it all, plus keeping the two rotors in synch. I've got the design drawn up for a balsa fuselage "mould" with which to build the fibreglass shell around. Batteries will be mounted slightly rear of centre to keep a central C of G.
I would like to go the scale route with all my Trex helis. I'm not all that keen on 3D, but then I haven't reached that skill level yet. Might be a different story when I do.

 

[Tony Mitchell]

Oh dear. I wasn't expecting that. I powered it up to takeoff speed. As it's spooling up it shakes side to side like crazy, but stabilizes as it gets towards takeoff speed. Back to the bench. Blades off, weighed both and both show 222g. Measured blade tip to mounting hole centre, both 78.2cm. Measured head centre to blade mounting hole, both 9.125cm. Viewed from above, with blades off, there is no deviation from centre of head centre hole. There is no play in either main or feathering shaft. Blade tracking is spot on. I'm really confused now. I've seen this with out of balance blades, but everything here is spot on.
What I have found is that due to the flexibility of the landing skid, the weight of the body is able to rock on it. Hmmmm.
Other than that, slight trimming to rudder and right swash link rod and it'll be fine. The wobble is a worry though with no obvious reason.

 

[fran11784]

Hey Tony, love that heli! I have one that is currently my oldest model. I bought it in 2013 when the kit was new. I believe they were shipping with different servos back then. But I have too many flights to count on it. I can tell you on mine that the heli will shake on spool up if the blade aren't tight enough. They are big long blades. You have to have them tight enough that they wont slip in the grips on spool up. Or a super soft start in the ESC. You will be able to program that with the USB dongle....

 

[D.O.G.]

Hey Tony. I hope the Flying Hippo joins in on this conversation. He has the exact same heli and would be a big help. The only thing he's on the other side of the pond. Here's one of his videos with his buddy's will contain bad language

 

[Tony Mitchell]

Hey Fran, the blades are tight in the grips, not so tight that I can't fold them back, but they stay in place with either a soft or hard start. It's not like an out of balance, all round wobble, just a side to side rock. Strange. I can hold the skids firmly on the bench, hold the body and rock it side to side, seeing the landing skid flexing as I do so. I would have thought that with the weight of this beast, the landing skid would be a little more firm.
I've measured, weighed, balanced and checked for play on everything, but everything is fine. The rocking is only at a certain RPM, it's rock solid at takeoff speed.

 

[fran11784]

Really sounds like ground resonance. Happens on full scale too. Maybe their to tight? Then it would take more RPM to straighten them out. If you cant solve it try to film it so we can see. I actually put the Quick UK skids on mine and put a support on the rear to keep it from sagging due to the weight.

 

[Tony Mitchell]

Hi D.O.G. that's one impressive flight. I like the lighting. I wonder if he runs that from the Rx battery or through a BEC. Hope to see mine doing that before too long. I just hope that we are able to go to the club flying field when we get a partial easing of the lockdown. It's boring just hovering around the back garden. At least I can throw the Blade Nano around a bit more. That one is a bit hairy outside though, as even the slightest breeze will take it. A couple of times with the Nano, I've had to ask neighbours "can I have my helicopter back please?"
I wonder where that airfield is in Hippo's video. Hangars etc visible in the background. When I was based at RAF Wattisham back in the early '80s, we were allowed to fly from the peri track over at the back of the airfield when they weren't flying at weekends. Later on, based at RAF Boulmer in Northumberland, we had the use of a disused airfield (Brunton airfield) (when our 202 squadron SeaKing rescue helis weren't practicing there). I could use the runway for the powered plane and the grass at the side for my Phoenix glider.

 

[Tony Mitchell]

Where did you get those skids from Fran? Are they more rigid than the originals as fitted to mine? How do I upload a video on here? It complained about the size of a photo yesterday.

 

[fran11784]

I just looked on the Quick UK web site and they are out of all of them. They are wider but not much more ridged. Thats why I added that brace on the rear one. I put my videos on Youtube then post a link here.

 

[Smoggie]

With big helis you do need to be a little more careful with spooling up. The shaking on the ground, off the top of my head, might be one of three things:

1. If you are using 'normal mode' you may be spooling with negative pitch which pushes the heli down on it's skids and destabilises it. You should always spool with very close to zero pitch on the blades (easiest way in not to use normal mode and put the collective stick in the middle)
2. The tracking is out. Check carefully with a pitch gauge that both blades are at the exact same pitch. Check one blade when it's facing straight forward, turn the blades 180 Deg and check the other.. Both need to be the same pitch.
3. Don't have the blades too tight (or too loose). The usual guide is hold the heli on it's side with blades out horizontal, they should not fall on their own, but if you give the heli a slight jerk they should both drop slightly and evenly.

A friend of mine was having some similar trouble so i did this little video, this is my Goblin 770, so similar size to your Trex: