Trex 500 lhs / stretch?

[trillian]

Just curious if anyone has tried to get the old style Trex 500 into LHS territory, or even just below 2000 ish. I always had to run mine about 2400 for it to all gel properly. I casually thought about stretching it but then the C of G becomes more difficult as it means moving the battery tray more forward, moving the canopy as well etc.

Maybe it just 'is what it is'. It would be nice to get slightly longer flight times, about 5 minutes was all I could get.

Anyway, I left my Trex in Miami last year as i was planning to go back in the winter (it's still there but no one to disassemble and pack it properly to post it back). So I started thinking about building up another one from all the parts I have.

(please pardon any typos, I'm on a train and some of the track is not smooth! )

[Nikki5]

I have run my Align Trex 500 as low headspeed on standard setup, just used 4s on the 6s setup. Its some time ago, but my impression is that the 500 is not the best low headspeed item..but i guess as stretched it could be better.


BA

[im4711]

I do not have any TRex 500 for a few years now since I mainly fly the HD500 machine. Its a bit larger disk compared to Align. However my lowest rpm was around 1050 rpm while I am able to do aerobatic at about 1300 - 1350 rpm.

Means 2000 is a bit of a medium rpm. Still anything around 2000 rpm shall increase flight time and actually at that level you should be able to do almost the majority of the maneuvers.

[ChrisOlson]

Kind of an old thread, but I'll throw in my 2 cents on an old-style Trex 500. Mine flies fine at 1,800 rpm and it will do 20 minutes. I'm using a Typhoon 500H 1800kV motor (which is not the most efficient motor you can use) on 4S with 13t pinion and 162t main. Pixhawk flight controller in it. 10,000mAh battery slung underneath. Swinging the stock 425 blades. Old HobbyKing Red Brick 70A ESC in it.

It had a flybar head on it. The link came off the elevator servo recently and crashed it. I'm waiting for a new DFC head for it.

It hovers on about 350 watts - 23-24 amps. And, of course, it has a lot of extra electronics in it along with the over-sized battery. Here's a photo of it.

If I put a different motor in it I'm pretty sure it would fly OK at maybe 1,700 rpm. But that would be the minimum with all the extra weight it's carrying. It definitely won't do anything but scale flying at 1,800 rpm and 2,300 gram takeoff weight. Maybe the new DFC head will be slightly more efficient - I don't know yet.

https://goo.gl/photos/GhGSmS9zf4RN6nWp8

[dicky-do]

I Like. did you make them? (Landing gear)

[ChrisOlson]

Yep. The landing gear is wider and taller than stock. It's made of 6061T4 hardware aluminum flatstock that I got at the hardware store out of their Might Metals rack, or whatever they call it.

It seemed like the best option to sling a big battery under it, and mount the Pixhawk. The Pixhawk is a big flight controller and not too many mounting options on a heli. It could be put on top of the tail drive case probably. But I got the GPS puck/compass mounted there, so I put the Pixhawk underneath.

It's a real fun heli to fly. Stable as a rock with the extra weight, balanced really good, and running sub 2,000 rpm headspeed makes it even more stable. And it flies long enough to have some fun with it. When the elevator link came off it was at about 20 feet altitude and it just nosed right in. Broke the blades (frozen ground) and bent the mainshaft. But it didn't hurt anything else. Hard to get parts for the old flybar heads - Align doesn't even have the mainshafts in stock for 'em anymore - so just ordered a new DFC head for it, which the Pixhawk will fly with no problem.

So I would call it a successful long flight time, low head speed Trex 500. I've been happy with it. Took a few mods, but the 500 is my "go to" heli when I want to fly and have fun and have the flight last longer than 6-7 minutes.

[aldrichg9]

Just FYI
Here is the right main shaft to use for the flybar 500 head
https://www.aligntrexstore.com/500PR...156_p_744.html
It's not the same as the original, have to use shims to adjust the height.
But it will work.
The trouble I run into is bent head blocks, have to go to used stuff for that.
I have gotten a couple off here.
I think amain was where I got my last flybar rod.

I know this has nothing to do with the headspeed stuff just wanted to let you know.
Oh and I run an Align 3300mAh and I am currently getting 7.5 minutes of slow flying coming down at 3.7 volts.
Haven't figured a head speed but I run 86-85-85-85-86 for a throttle curve. (like I said... easy flying)

[ChrisOlson]

Originally Posted by aldrichg9

Just FYI
Here is the right main shaft to use for the flybar 500 head
https://www.aligntrexstore.com/500PR...156_p_744.html

Yeah, that's the one that's out of stock for the last two months and it says "put me on the waiting list".

So I put a DFC head on it. Flies great.

https://goo.gl/photos/KyACdYTrkx8dSwZb9

[aldrichg9]

Hate to hear that.
Wish I had known I have a couple here that I probably won't use. (I bet I bought the last of their stock in December).
Also, aligntrexstore does have real live people that answer the phone.
Gale can help you get what you need or get you pointed in the right direction.

Anyhow, glad you got it flying the way you want it!!

[ChrisOlson]

Thanks - it took me a bit to get the Pixhawk tuned in to fly the DFC head, but I really like it. And it is slightly more power efficient than the flybar. She hovers on 19 amps and I got 29 minutes and 15 seconds with it in a hover test, pulling the battery down to 3.65vpc. Safe for the battery would probably be 23 minutes flight time. The head is lighter and takes just a bit less power to turn. And moving the rotor down closer to the heli I think improved the general "feel" and handling too, at low headspeed.

So I'm pretty happy with it.

[aldrichg9]

Originally Posted by ChrisOlson

I got 29 minutes and 15 seconds

Nicely done.

[ChrisOlson]

Thanks, yeah. I really like it. Here's a vid of the LHS Trex 500 flying with pure rate mode in the Pixhawk, using Acro. It flies great.

Wife caught it with her cell phone camera because she thought she might get the epic crash on video. First couple times I tried to take off with it, the heli was sitting tipped to one side on the ground, and I fed in some stick input on the cyclic before takeoff. Well, don't do that in rate mode. It stores up the stick input and makes the heli do some really fun things on takeoff.

Just leave the cyclic alone and once it lifts off, then start flying it. Wife says, "oh, that's better". LOL!

[ame="https://youtu.be/3Unq6nFSxxA"]Trex 500 Pixhawk Acro takeoff/landing test - YouTube[/ame]

[Helikapoter]

I fly the Trex 500 with a scorpion engine (1200Kv) and a set of assymetrical Spinblades with a rotor Rpm of ±1700 .
Here a little movie of it

Align T-rex 500 ,Bo-105 , scale rc helicopter,electric helicopter (1 min 12 sec)

Arno,

[allegro16]

I'm flying my 500 size Jayhawk at a very low 1,450 RPM
That is with 4 x Helitec 470mm semi symmetricals
Despite the very heavy weight of almost 4KG, it flew with sufficient collective/cyclic authority
The tail is 4 bladed with 4 x 80mm tail blades, so no problems with tail authority.