2015 Project #2 - "Super" Trex 500

[Derek]

I've been thinking about this project for a very very long time. It's probably a project of lunacy but I will admit that I don't share all my projects with The Hangout nor Youtube. I wasn't going to share this project until it was working properly but, in all honesty, I'm going to need a bit of help. I'm hoping to avoid those comments like 'This is a waste of time and money" because I already know and understand that, lol

So...let's get to it. I have a used Trex 500 Pro DFC. I want to make some mod's. I want to run an 8S setup. I want to run 500mm blades. That being said, the tail is going to need stretched. All of that is probably "all and well" but here is where things take a twist. I want a 550/600 tail boom and tail rotor. So, I'll need a tail boom case for a 550/600. Obviously it's going to be much too wide to fit inside the 500 frame. I have a very good precision mill that I can use to make the tail boom case narrower and I can remove the same amount of material from both sides very evenly. Those hexagonal parts can also be shortened very precisely and I have a small tap set that I can use to retap the threads into the hexagonal pieces.

I'll need a 550 tail boom cut down to a proper length. I don't have that number with me right now but I have spoken with other people that have stretched their 500's and I have a length written down for proper use. I have a proper length for the torque tube to get cut down, as well and I have a part number for replacement torque tube end pieces.

I really don't see any troubles with anything that I've mentioned, above. Here is where a question is...the front torque tube drive gears. Align has parts for the 500 that are MO.6 31 and 36 tooth gears. Align has parts for the 550/600 that are MO.6 40 tooth and MO.8 34 tooth gears. If the 500 runs the 31 and 36 tooth gears, which of the 550/600 gears should I look for?

I have the new motor and esc chosen for this project. Of course the motor diameter is a bit too wide to actually fit inside the 500 frame so I'll be removing a bit of the carbon fiber from the side frames. Not much.

[cml001]

Intersting...

[Graham Lawrie]

That all seems do-able:)

[Derek]

That all seems do-able:)

Thanks Graham! I appreciate that! Really, I think I just need to sort out the gear ratio for the drive gears and then it's just a matter of building it. I'm going to start ordering parts within the next couple of months.

[Graham Lawrie]

The only issue Derek is non-standard spares LOL:)

[Derek]

The only issue Derek is non-standard spares LOL:)

what do you mean?

[Graham Lawrie]

Just a joke Derek:) as the build is non-standard:) i know you are using stock parts but putting your own twist on them:)

[Derek]

ohhh, ok, lol. Yeah! I think it will work pretty well. I like the look of the large tail boom on the Velos 880. That's the helicopter that inspired this idea. I was just thinking that a larger tail boom, with longer torque tube and larger tail rotor, would add substantial tail weight. To counter that and add nose weight, I want an 8S battery setup near the nose. Then, to help handle the "performance", despite the added weight, I want to run a higher wattage motor with 500mm blades.

[Graham Lawrie]

That really sounds do-able:) I dont thing the tail will affect it as much as you think other than COG weight, which you will correct with the extra nose weight:) Looking forward to seeing this:)

[Derek]

Thanks Graham! First, I've got to finish the build on my large 3D scratch build plane then I want to order parts for my #1 2015 project. I'll get it built and then I'll start this Super Trex 500.

[Tony]

Sounds like a really cool project Derek, hope everything goes to plan for you..

[Derek]

Thanks Tony! I think this will work out very well. It will just be a matter of acquiring all the parts and pieces from the 500 and 550 sections of Heli Direct, lol. I'm thinking there is going to be some "trial and error" in regard to the gear ratio. I'll probably have to change the pinion gear and front drive gears a few times in order to find a safe and suitable compromise between the main head speed and the tail rotor speed.

nonetheless, I'm quite excited about this. I'll get a few previous projects completed and then we'll get started on this build. I'll post any updates as they arise. I'm hoping that Paul, Lee, Marius, and Dan all chime in on this thread. I regard them as the most experienced flyers that we have in the Hangout and I respect their opinions.

[Tony]

Sounds good, but if you ever need your heli to find water for you then I'm your man... Lmao

[Lee]

I'm guessing you have seen this video then Derek?
Insane power.

https://www.youtube.com/watch?v=orHiutfmUTQ

[KevG]

Great project Derek be following you on this,

Derek as your prob aware with concerns of the tail weight balancing the added weight at the front, the added size of the bigger 550 tail case and moving it further away from the pivot point I think will make it to tail heavy, the 500 case further away on the stretched boom might be enough in the first place, what is the weight diff going from 1 6s 2700 to the 2 4s xxxx cells that your planning on using,

I think the 550 tail will be to much mate,

[KevG]

Also will be putting the esc on the side frame so that will be inline with the main shaft not under the battery tray again helping with cog

[danhampson]

That is bonkers.

Derek have you thought about buying some carbon tube and rod to make the boom and TT you could strip the hardware off an original TT for the carbon rod that way you may not need to mod a 550/600 boom case.

Ive seen msh protos stretched to 550 using carbon tube and a longer belt, There where no other mods other that the stretched tail gear to speed up the tail rpm.

https://www.youtube.com/watch?v=UtIrdyOWDR0

[Tony]

I thought the idea of training gear was for that exact purpose, to learn how to fly at low altitude, that guy certainly doesn't appear to need those....lmao, but nice heli

[Lee]

I use to put training gear on anytime I made a major change in set up, new parts etc. Saved my heli a number of times when something unexpected failed.

[Graham Lawrie]

+1 on Lee:) and i still do for the initial spool up:) And when i was watching this, the last time i flew my 550 with confidence was when the gear was on:)