700 size blades on T rex 600 ?

[guyken]

THX for all the replys guys . I think we will have to see in practice . And no it is certainly not for 3D flying . Longer tail boom (stretched to 700 ) can be compensated by larger lipo in front , 6s 5800 or so . And later on by cockpit and pilote figures . A lot of work to do but first the heli must fly like it is now . I think next weekend i will have a go . Will post result here .

[RC/DC_5000]

Here's an example in practice from one of the most elite helicopter companies on the market.

The Goblin 700 with or without the new Triple bladed head. Now a three bladed head is more "efficient" at creating lift... they provide more lift per rotation. As such, SAB turns the headspeed down as a result.

But guess what? They still post a 160A MINIMUM ESC with the Triple bladed head. And they post a 120A minimum ESC with the Double bladed head.

The added surface area and weight of the disc is going to draw more current battery from the battery especially under load. Hence the larger ESC requirement. Even with a lowered headspeed.

[RC/DC_5000]

Originally Posted by Grumpy_Old_Man

Note that efficiency can never be defined in terms of a single variable. By definition efficiency is the ratio of one variable vs another. So there is no such thing as 'lift efficiency' or 'power efficiency'.. Efficiency must by definition be a ratio of one against against another, i.e 'lift to power efficiency'.

Power Efficiency is the ratio of current consumed versus output power. There is definitely such thing as power efficiency. Google it. OMG seriously! Are you not embarrassed every time you get caught making things up?

"The efficiency of an entity (a device, component, or system) in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression), typically denoted by the Greek letter small Eta (η - ήτα)." - Copied and Pasted from FIRST GOOGLE SEARCH.

"Lift Efficiency- In aerodynamics, the lift-to-drag ratio, or L/D ratio, is the amount of lift generated by a wing or vehicle, divided by the aerodynamic drag it creates by moving through the air." Copy and Pasted from FIRST GOOGLE SEARCH.

You always argue with me and end up embarrassing yourself. Yet you continue time and time again to touch the hot stove. Like when you said a battery does not fill a wire with electrons. No such thing as power or lift efficiency huh? WRONG.

Stop making things up as you go and read and research more. For your sake. And for mine. These super obvious errors of yours (again) should be a wake up call.

Grumpy- every time you reply to my posts.. Im going to cut and paste this post as my reply to you. To remind you to stay in your lane.

[guyken]

I am going to tell you guy's some more why i am going to try 700 blades on t rex 600 . First of all i wanted second opinions here on the forum because so far i had good experiences here from people who know there "business". The more one knows the better . That is my opinion . Second opinion yes , so what is the first I am being helped by a man who is also member of the club i am flying with . This man has about 30 years experience with rc heli's both electro as nitro . Now he is Vario dealer in Belgium so he knows a lot about scale heli's and their equipment . That man is Guy Vanderschelden from Heli Tempel . It is the same man that says that what i am going to try should be possible . Together we came to solution for 170T main 10 T pinion for 1220 kv motor on 6s . The esc we both don't know yet because i told you guys its HK . If it burns out whatever , won't be a great loss and then i put a Kontronik on it . I fly my Agile 7.2 on 12 s with Jive 80 + HV .

[RC/DC_5000]

Yea I also agree that what you're looking to do will probably work for scale hover flights.

In that sense, we are all expressing our opinion really. What I'm settling with Grumpy, is him making up factual information as he goes.

IE- saying there is no such thing as power efficiency.

[nightflyr]

JMHO here...
If your using the intended setup for scale flying I can say you'll have a nice setup providing you have the correct gearing and motor Kv.

As to how well a larger disc will preform ...
Depending on how you plan on using it ....

I can tell you putting 1000mm blades on a 600 stretch running 6S can yield you roughly this @ ~ 15.5 lbs AUW.



When I add ~ 28 lb payload to the basic machine, Current draw rises to ~ 35 - 40 A
That would be cruising around, no 3D.

As to flying 3D,
Many have done it on 6S, straight or stretched.
Some simply leave their 12S setups as is and just plug in a single 6S pack.
Others swap motors, gearing and /or ESC's to run 6S on a larger machine.
Can a stretch 600 on 6S fly scale or 3D
I think this thread will give you some insight.
https://www.helifreak.com/attachment...9&d=1340147543

[guyken]

Tried a spool up today very gently but bad result The heli shook and did the hibby hibby shake The blades were well balanced before spool up but i didn't put 700 size tail blades Could that have been a mistake or is the head not strong enough for 700 blades . I have a RJX rotorhead No accidents but i didn't go all the way .

[nightflyr]

First off ...
You need to make sure your blades are straight prior to spool up.
Next they need to be the correct tightness.

Question ...did you spool up on grass or a hard surface?

As to if the RJX head is strong enough....

If I can spin 800mm, 900mm & 1000mm using RJX heads, I see that spinning 700mm would pose no issues.






I don't believe the issue you experienced was due to your tail blades.

[guyken]

Blades were straight but it was on hard surface , perhaps better on other surface You say that tail blades don't have influence but the tail didn't do anything and when i put 600 blades on the heli it spools up nice and reacts to tail inputs .

[nightflyr]

Ground resonance is a issue, more so when spooling up on a hard surface ...

Hughes 500E Vario first flight (1 min 29 sec)

[guyken]

Wow that was painfull to see . I am thinking to put 690 blades instead of 710 and RJX blades so i am sure they fit the rotorhead.

[guyken]

Today another try with MAH blades , better fit then SAB blades but no way José . I am doubting now about my RJX head is it 50 or 90

[guyken]

First flight today with 600 blades and success Smooth take off and lovely farthing of blades on low speed . Nothing heats up ( lipo- motor or esc ) After 5 minutes of flight ( not 3d of course ) still 60 % in lipo . Nice set up but still want to go to 700 blades . Is there a difference in RJX 50 or RJX 90 rotorhead ( bigger , heavyier )

[nightflyr]

The only difference I have ever know is the main shaft bore ...

10mm for the 50
12mm for the 90
Everything else is the same between the two heads.

As I said I fly 1000mm blades with the 10mm RJX head.

1000E / Naza H (4 min 26 sec)

So you need to look at your setup to see where your issue is originating from.

[guyken]

I see , thx for the movie . You are right i have to look elsewere .

[goodhunting]

I know this is a 600 stretch to 700 thread but I just stretched a 700 to 800...
Same principles apply though...

I simply swapped the tail boom and main blades... lowered the head speed a bit and even kept the tail blades the same length...

maiden today and no issues what so ever... just glanced over the logs and there are no issues that would catch my eye...

gh

[guyken]

Yeah should be same . I am going to have a look at the feathering spindle and dampers .

[guyken]

Man after all these years still stupid mistake . Blade holes are 5mm , bolts 4 mm . Problem solved flies sweet now with 700 blades

[goodhunting]

great news...

gh

[guyken]

THX , next step scale fuselage ( Huey ) .