Shorten my Trex 600N

[ticedoff8]

I upgrade my Trex 600 nitro to the new 550 / 600 3 bladed head and tail.
I am currently flying it with 3 600mm mains and 3 95mm tail blades

I use a YS 60SR and Hatori pipe which has always been a tiger with the 2 DFC bladed head & tail @ 2100 RPM headspeed
Now, the YS is become more of a kitten

So, I bought some Zeal 550mm mains and the parts needed to replace the 600mm tailboom with the 549mm tailboom (from the 550E).
I will stay with the 95mm tail blades

This has some benefits (I think):
1) Shorter blades equal less load on the motor
2) Lighter weight overall (shorter boom allows me to remove some nose weight
3) Mass centralization. Shorter tailboom and less nose weight makes the aileron rotation more responsive.

The parts are on the way.
I expect to see the new tailboom parts and the blades before the end of the week.

Keeping in mind that there are 3 blades, I figure I can still run the head at 2100.
This has always been a comfortable 17,800 RPM on the engine and even with overspeeds, it rarely exceeds 18,500.

It was either this, or do a big block conversion (YS 91SR-3DX) and keep the 600 tailboom and 600mm blades
That would be awesome no matter what.

If I could find a 21T pinion, I could change the GR to 8.1:1.
That way, I can spin the head @ 2200 and still be at 17,800

I could even use a 22T pinion and speed it up to 2300. But, I figure that is trading aero loads for torque and I wouldn't be able to reap the rewards of 2300 RPM headspeed.

I am committed to the 550 tailboom and that is easy to reverse back to a 600 tailboom.

Thoughts and opinions?

[dominator]

Originally Posted by ticedoff8

This has some benefits (I think):
1) Shorter blades equal less load on the motor
2) Lighter weight overall (shorter boom allows me to remove some nose weight
3) Mass centralization. Shorter tailboom and less nose weight makes the aileron rotation more responsive.

1) shorter blades but your adding a 3rd which is less efficient than a 2 blade setup. So for the same amount of lift the motor consumes more power.
2) You may be removing weight by cutting off 50mm of tail boom but your adding a bigger head and the weight of the 3rd blade which weighs more than the tail boom.
3) The mass will be a little bit more centralized

Not trying to burst your bubble. Try the 550s on the 2 blade head and just crank up the headspeed and pitch see if thats what your looking for.

[Number]

Just bought a 600N. I plan to run 570s.

[dominator]

IMO the perfect set of blades to run on a 600 size nito are ms composite 60cm. They are super lightweight and not as wide as rail 606 but more wide than sab 570's. So you get the extra lift but they dont bog down the motor when your using alot of cyclic.

[Number]

Are you talking about the old 570s? I was planning to try the Thunderbolts.

[dominator]

Yes i was refering to the older 570's. Ive only flown the 650 thunderbolts. Im not sure if they are wider than the older 570s or not. The thunder bollts fly ok but cyclic was a little to slow for my taste

[SlezY83]

I would say, that it have to be a monster if you use 3x600mm blades and OS 105 engine.
If you are interested, I have big block conversion for GT15HZ600 for sale, which works for 90 size glow engine as well.
I have 22T pinion and 23T pinion as well for it...
The advantage is that you will use all of the 600N stock parts (clutch, clutch bell, gears,...).
PM me if you are interested...

[notredan54]

How is this working out? Think i might go a similar route for my flybarless conversion.

[ticedoff8]

I have not had the time to make the change - but I have all the parts.

I also found a good deal on a YS 96SR-X w/ YS Power Pipe.

I will try shortening the 600 to a 550 first and see how that flys with the YS 60SR.

I will update the thread with the results.

[ticedoff8]

Update:
Still not flown yet. Too busy elsewhere
But, all the 550 parts fit perfectly
I had to buy the 550mm main and 90mmm tail blades to complete the setup. The 95mm tails actually touch the 550mm mains when I was rotating it on the bench.

The CF tail rotor control rod is a perfect fit. And, provides all the adjustability needed.

The tailboom is about 2" shorter (549mm vs. 600mm) and that allowed me to take off a lot of the nose weight to get the CG correct.

Overall, it is lighter than it was and the disk loading is lower.
I hope it has some pop to it.
And, with the 3rd blade, I expect better collective and cyclic response.

[Lanky]

Looking forward to hearing more!! and keen to see what pitch ranges you use and how it works on the motor. awesome idea mate! the hobby needs more guys experimenting!

[notredan54]

I'm with Lanky, look forward to more!

[ticedoff8]

OK; This has promise. But, it is not as great as I had hoped for.

I flew 6 flights Friday / Saturday

#1) The YS 60SR is at its limits with the 3 550mm blades.
It may be because the motor needs a rebuild.
I will change out the ring and main bearing and see if that helps

#2) The cyclic response is bad. It is super slow.
I have been advised this is because the Zeal 550 blades are designed for a 2 bladed FBL head.
This makes them heavy and the CG is too far forward so they are "super stable".
This becomes more evident when the heli is under-powered (AKA: Nitro vs. Electric).
Blades that are lighter with the CG more towards the tailing edge are less stable. The old flybar blades were like this.
I may have to play around with different manufacturer's blades to see if I can find the "right set".

But, I will not be changing back to the 2 bladed head
I will find the right combination to make this work well.

[dominator]

Try Ms composite blades. They are really fast on cyclic and lightweight. I believe they sell them in 3 blade sets as well. The only downside is you have to buy them from Europe but the shipping is still pretty fast

[ticedoff8]

I am not familiar with "Ms" blades
Do you have a link?

[dominator]

Originally Posted by ticedoff8

I am not familiar with "Ms" blades
Do you have a link?

http://www.mscomposit.net/

[Lanky]

Hi Mate,

not sure if you've seen this vid, he talks a bit about cranking up agility settings and blade weights when adding a 3rd..

Raptor E700 Tri-pop 3 blade head with Nick Maxwell (2 min 35 sec)

I've only tried one flight on my 700 with zeals, they did feel like pack killers and power hungry but that was only one flight.

The only thing I would say to try is a set of 3 blades either by thunder tiger from their 3 blade 550.......... https://shop.thundertiger.com/collec...ade-combo-3934

or the SAB 570 3 pack. From memory the mass of the 3 rotor blades needs to be roughly the same as the mass of a usual 2 rotor blades.

[ticedoff8]

I've only tried one flight on my 700 with zeals, they did feel like pack killers and power hungry but that was only one flight.

The only thing I would say to try is a set of 3 blades either by thunder tiger from their 3 blade 550.......... https://shop.thundertiger.com/collec...ade-combo-3934

or the SAB 570 3 pack. From memory the mass of the 3 rotor blades needs to be roughly the same as the mass of a usual 2 rotor blades.

From a pilot I highly respect and is part owner of an RC helicopter / FBL gyro company, and who has flown about every blade on the market for his company's new 3-bladed upgrade to their power house 700 size heli:
He recommends the Align 690 blades. Period. End of sentence.
Quote: "Everything else is crap"

I have the Zeal 690 Energy Carbon Fiber blades on my 700N 3-blade.
They were crap.
They weigh 180g each

I bought the Align 3-blade pack (AGNHD690DT) but have not flown them yet.
They weigh 166g each.
Not, great, but better.
And, they are recommended by the "pro"

I am looking at the MS Composite CFC 60cm (600mm) blades.
These are designed for flybar equipped heads.
http://www.mscomposit.net/CFC-main-b...-RAPID-d88.htm
They weigh 120g each
Compared to the Align 600mm @ 136g each
But, that would be if I stretch it back out to a 600 size.

For sticking to the "shrunk" 550 size, I bought a set of SAB 540-3D
I have not flown them yet.
They are 98g each.
But, they also have a narrower cord: 43.5mm vs. 48mm (Zeal)

But, the Zeal 550 blades are not cutting it.
They are 116g each (I know, they are 10mm longer too)

The interesting thing is that MS Composites has a 55cm (550mm) FB blade too. They are supposed to weigh 110g

I will look at the TT blades.

I am also bought new 21t & 22t pinions for the 600.
Then, I can spin the head faster (it is a YS 60SR).
The 170/21 = 8.1 and 2200 RPM HS @ 17.8k engine RPM
The 170/22 = 7.72 and 2300 RPM HS @ 17.8k engine RPM.

I figure the 60 should be ok with the 8.1:1 gear ratio.