Query on what Blades u use for DDrive in Dragonfly.

[loyn]

Just my 2 cents idea, may be you guys can try the GWS EDF50's 3 or 5 blades impeller. They are of smaller in size but of high pitch. As I know the EDF50 by itself may drawn high current. So not sure how it work without all those duct.

[D.Yeo]

We need bigger diameter lower pitch

As we're dealing more with static thrust or thrust at very low airspeed since our tail wont be turning so fast, think our ideal prop will be a large diameter with low pitch.

All these direct drive and especially DF setups are pretty lousy and are inefficient at low airspeed ( tail rotor ) application.

Actually a gear drive would give us a more suitable setup.
nice big low pitch prop. just that for us it seems our gear drive option is quite an easily burnt out one....so not much choice other than DD. So while we're using DD we might as well try to get as close to our ideal big diameter low pitch prop.

it'd be much better if we could fit perhaps an EDF motor with a gear drive on the back and spin a big prop. think i actually saw somethign like that on one of my friends helicopter carcasses.

[Super-Hornet]

I did some experiment on Geared Drive using IPS before and what I notice is that:

Geared Drive IS SLOW when u want to do FFF or Fast Up/Down. Geared Drive ratio actually slow down the motor spinning response also. In order to use Geared, your propeller blades size needs to be big. That is why u see those stock Geared Drive propeller are big. (It doesn't look cool and realistic size ratio... as compare to small propeller like EP-3020)

So, IMHO, Geared Drive is slow. DDrive is fast. Using Bigger blades or better pitch will give your better authority But due to CN12-xxx design has a fault so if you over load it, it will burn out.

Using EDF blades may be weak in this case due to its blades are small in surface area. I think if I use 2 EP2510 propeller it perform better than EDF blades only...just guessing.

Super-Hornet

[D.Yeo]

Hornet : yeah i agree with you the gear drive option we have is too slow.

But that's because the gear ratio we have is too high and response is really quite slow
that's why we all have to use a DD...

And i also think the silly huge prop looks quite cock too heh....



What i meant i think would be ideal is :
a redcution ratio , but of maybe 1:2 or so.
A very low ratio hmmm imagine the spur gear is only about double the diameter of the tiny pinion,unliek what we have now.

That way what i think what we will get is the ability to use a 5030 prop at roughly the same RPM, without burning the motor out.
i find the response of the DD in FF very nice but think it's still lacking in power when there's wind about.had a few scary mama moments like that heh.


Maybe we could engineer somethign like that eh hmmm...any ideas? need to find an alternative mount , probably not worth the trouble heh...

[Super-Hornet]

If you want to create 2:1 ratio, maybe using IPS gear with some unusual spur. U have to those spur. I once ever mounted a Tamiya Mini 4WD motor (2mm shaft) onto a IPS gear and then connect 3 EP-4025 propellers. What I get is a 6 blades propeller. I did try mount that 6 Blades combinations onto my Dragonfly. It is powerful but too bad the ratio i have is 6:1 (I think). So speed not fast enough.

Super-Hornet

[loyn]

Hi guys any idea what is the gear module for the tail rotor, 0.5, 0.3 or 0.25 as we need this infor for making our own gear box.

[D.Yeo]

hornet : funny that you tried that, just now i was walkign about during lunch and was looking at these tamiya mini 4wd gears hanging at kiddy palace and was thinking of suggesting exactly that !

Hmmm maybe with your reduced ratio you should try the stock tail prop ? with a bigger motor producing more torque we should be able to end up with a faster turning stock prop...


Loyn : i dont know what module or what pitch they are leh... but i'm sure with so many heli modifying guys around someone is bound to know....

for now i think we can be happy simply calling them tamiya mini 4wd compatible, or non tamiya mini4wd compatible...

Will you both be at the fun fly tonight as well ?

[loyn]

Yap, I will be there for funfly, will not miss it for the world.....

Well for sure those Tamiya gear (metal 8T not miss taken) will fit the main rotor gear, as me any Joe have been using it for sometime on both 370 and CD-rom motor. Howeve, the mounting center hole is too big for the IPS motor unless you want to try other motor such as the 180. The weight diff will be significantly increased. Just my 2 cents input

I intends to try using coreless motor but they are much more expensive (about US$23) but are more powerful and light (10g only for the motor) Most of all they drawn much less current than the normal tail (B2C) motor. Again is the gear box and ratio have to be figure out...