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HomeScaleAircraftScale HeliScale Helicopter Main Discussion Docs  Vario Bell 412 electric
05-02-2015 07:49 PM  3 years agoPost 1
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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OK so where to start...
this is my first Vario model... and I know that it is an older model... not as popular as the EC series... but it is near and dear to me....
I'm not smart enough to fly one but they let me dingle underneath one every now and then on various ropes...

So when the mailman dropped off the big box I was really excited...a lot like my kids at Christmas time..

Now just to warn ahead of time... this will be a long time project... My work and family come before my hobby so this will take some time to build...

gh

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05-02-2015 08:12 PM  3 years agoPost 2
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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Beofre I started and when I was still gathering information I really wanted to know if I can fit the Trex 600 of Trex 700 mechanics as I have a couple at home...readily awailable,...

Well since the fuselage is made to fit Vario Skyfox mechanics I got a used set for a decent price... and I wanted to see how they fit...

but the view without a cut opening for the doors does not tell much... so I had to open up the fuselage.
I used the tape method as described by Ian... aka Satsuma and it is so easy that even I could not mess things up. When I opened the fuselage I got a different perspective on things...
The Skyfox mechanics do work but I got a set of hanging mechanics, which are a lot like Skyfox only smaller and hence lighter. They are still as sturdy as Skyfox...but they leave more of the interior open for the scale details....

now I took the skyfox mechanics and compared them to Trex 600... they are both rather equal in size... and with the beefed up FDE main gear and third bearing block they would work fine. The issue remains that the tail output sits higher than the Skyfox...

And then I took the Trex 700... as I only have one of these and it is in flying condition... I placed the Skyfox mechanics in front of the helicopter. As obvious from the photos... the Trex700 is a bit bigger but if I were to remove the front electronics tray they are both the same size. Again the issue of higher tail output can be tackled two ways... either using flex shaft (and I have no objection using those, have one in my 500 size and one in the 600 size helicopter) but in this build I would prefer the Torque Tube...

gh

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05-02-2015 08:17 PM  3 years agoPost 3
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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anyhow... playing with the fuselage further... I noticed that not everything fits...as it should...

When I placed the top cover on the fuselage I noticed that the mechanics are not positioned correctly. The main shaft sits way forward of the centerline... (not the length of the main shaft is not correct for this build and I will get a longer one... in time)

Then I used the hanging mechanics as they could be placed in the correct position easier, adn at the same time clear the inside of the helicopter...for more details...

gh

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05-02-2015 08:21 PM  3 years agoPost 4
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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And since I had some time to kill today I kept pondering the hanging mechanics further... I want to convert the mechanics to e-power...
all such setups I've seen before had the motor placed in front of the mechanics... BUT I was contemplating placing them behind.. hence freeing more space... for the inner details...

I used an old Align electric motor as mock up knowing that a 250Kv motor that I need would be smaller in size...

any thoughts? suggestions??? concerns????

gh

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05-03-2015 07:11 AM  3 years agoPost 5
rcheli808

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Mililani,Hi-USA

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Looking good GH...

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05-03-2015 12:53 PM  3 years agoPost 6
MattJen

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UK

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When I placed the top cover on the fuselage I noticed that the mechanics are not positioned correctly. The main shaft sits way forward of the centerline...

I found the same thing when using the trex mechanics and a vario fuse.

I just got the mechanics to sit as far back as I could and traded off where it should be verses where it was, mine is slightly forward of the centre point, but checking the CofG it is fine,
also remember you may have to get to the tail boom to remove the mechanics, so having the boom screws easily accessible will save you a lot of frustration in the future.

As to your motor you will need to work out the gear ratio verses the KV, you are looking for a head speed probably around 1300/1450
there are calculations

RPM = kV x (3.7V x # of cells) x 0.9 (efficiency) x pinion teeth / main gear teeth

12S 115 main 15 pinion 300 KV
1564 rpm HS at 100% ungoverned
1408 rpm HS gov at 90% leaving 10% head room in the esc.

the above figures were given to me I opted to run 10cells and use the KDE gear and pinion upgrades which you will need for running bigger blades.

10S 115 main 16 pinion 330 KV
1529 rpm HS at 100% ungoverned
1430 rpm HS gov at 90% leaving 10% head room in the esc.

as to your motor being behind you are going to have to re design a lot, the trex is designed for front if you decide to use the trex 700.. but as I have seen on this forum anything is possible.

I know the skyfox does an electric conversion so it may be better keeping it all vario.

Good luck

All The Best

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05-03-2015 03:20 PM  3 years agoPost 7
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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Matt

Thanks for the explanation. Currently I.
'M leaning more towards using the hanging mechanics from Vario....

Got the math figured as well and with the current gearing I would need a 250 Kv motor to run those....
Just pondering where to fix the motor....

Gh

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05-03-2015 09:10 PM  3 years agoPost 8
Mojave

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Palos Verdes, Ca. USA

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I believe that the skyfox mechs that you have are actually vario Kobold mechs. The Kobold mechs were a cheaper version of the skyfox and came with an all plastic intermediate gear. It appears that the hanging mechs also have this same intermediate gear. IMHO, if you use either set of mechs, I would upgrade to the steel intermediate gear, as the plastic gear is very prone to failure. Also, it would be wise to do the electric conversion with a clutch, as it's much easier on the skyfox gear train. If you use the skyfox, you can modify the side frames to allow the use of a 65 tooth main gear, which will give you more motor choices. It's a simple mod, you just dremel away some material for the gear to clear the frames. I used a 400KV motor with clutch on a 65 tooth gear in mine.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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05-03-2015 09:47 PM  3 years agoPost 9
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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Barry. That is great news.. I was looking at the upgraded main gear but did not seriousy consider using the clutch... Although I know the purpose behind it and the sound of the setup is cool. It was the Kv that got my interest. Did you use this setup on a four blade heli or on two bladed one? Could you share the parts that you use for the clutch upgrade and what size pinion did you run with it?

The "other scale site" suggest goblin mechanics setup and I don't think I can fit it under the top cover on the fuselage as the motor sits too high...

I'll most likely go with the hanging mechanics but still need to figure out how to do the complete layout....

Gh

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05-04-2015 04:05 AM  3 years agoPost 10
Mojave

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Palos Verdes, Ca. USA

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I ran skyfox mechs on 2 and 3 blade helis. My 800 size huey and my Schweizer 300 both had them installed and both had the upgraded steel gear and clutch.
I think 44/70 is the PN for the 65 tooth main gear, but Joe at East Coast Scale Helis can confirm it. Scale spool up is cool, but is not the only reason for the clutch on this set of mechs. The skyfox was not designed for e-power, so the gear train is really put to the test with an electric motor and NO clutch. Which is why I recommended the clutch for your set up. I would also set your esc up with low governor gain, that way it limits the hit to the gear train when you give hard pitch inputs (like during an aggressive climb out).
I used the 22 tooth clutch PN 64/35. You'll need a motor with an 8mm main shaft for the split collet to ride on. Also the steel intermediate gear is PN 36/48. I know it seems expensive, but I would not do this mod without the steel gear. Or, you can upgrade to Benzin or Vario electric mechs and sell the other mechs that you have to offset the cost...
My personal opinion is that you don't gain unobstructed cabin space with the top mounted mechs and you do have to find a way to mount them securely, then figure out a way to run the clutch. So, that being said, I think you are better off either running upgraded skyfox mechs or upgrading to benzin. My personal favorite would be benzin. You will get many years of trouble free, bullet proof service out of them.
Barry

This is my custom e-power conversion for the skyfox. It mounts the motor up high in the frames.

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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05-05-2015 08:04 PM  3 years agoPost 11
MattJen

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UK

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nice work there barry

All The Best

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05-06-2015 12:45 PM  3 years agoPost 12
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

My Posts: All  Forum  Topic

Barry

thank you for the explanation. I'm sorry for the late reply but I'm on a business trip and days are rather full...

So I took your advice and did some math...
Vario Skyfox mechanics is a two stage mechanics with the 1st stage
65t main / x t on motor (of clutch)

2nd stage has internal gearing with 40t and pinion with 10t

I compared A - 20t clutch, B - 22 t and C - 24t
and used the 12S (44.4V)setup

after a few math problems I determined that a 450Kv motor should not be hard to find and at 100% that would give me:
A - 1536 RPM
B - 1693 RPM
C - 1850 RPM

If I govern this at 80% then I get
A - 1228 RPM
B - 1354 RPM
C - 1480 RPM

so if I stay with this motor I would need a 22t clutch to get a desired HS of 1400...

if my math is wrong please correct me..

gh

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05-06-2015 05:53 PM  3 years agoPost 13
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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did some more math... on a rather lengthy meeting...

and I came up with what I believe to be a feasible combination...
480Kv motor and a 22t clutch... gives me the range from 1300 to 1500 RPM without "endangering" the ESC...

next best thing is a 450Kv and 22t combo... which gives me the range from 1230 to 1400 RPM

the question for the wise is should I run a 1500 or 1400 RPM for this helicopter?

gh

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05-07-2015 01:42 AM  3 years agoPost 14
Mojave

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Palos Verdes, Ca. USA

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IMHO, a good head speed for this heli is going to be in the 1200-1300 rpm range. With the 22 tooth clutch and 65 tooth main gear mod, the final drive ratio is 11.82:1 (rounded off). Given a best case of 90% efficiency from the motor, 12S, 400KV nets you approx. 1353 rpm head speed at 100% ungoverned, but you need to leave some head room in the esc. So governed down 6% (running at 94%) nets you a head speed of approx. 1271 rpm. This is where I ran both my Huey and Schweizer 300 and they flew like a dream.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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05-07-2015 05:52 AM  3 years agoPost 15
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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here is my predicament... A new clutch from Vario costs 90 EUR... I can pick up "new in package" stuff from classifieds 22t for 29EUR and 24 for 59 EUR...which is significantly cheaper...

If I use the 20t clutch and 400 Kv motor... then at 90% governed HS I get 1229 RPM... which is what I am aiming at?
with this setup I can drop down to 1092 RPM should I really want to without seriously endangering the ESC....

gh

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05-07-2015 09:42 AM  3 years agoPost 16
Andy01

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Brisbane, Australia

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GH

I think you may have forgotten to factor in an efficiency factor.

RPM = 450kV x 44.4V x 0.9 (efficiency) x (10/40 x 20/65) = 1383rpm at 100% towards the end of the flight.

So, depending on what ESC you have governing to 80% (which is too low for CC ESCs, and probably most non-freewheeling ESCs because it is likely to run hot) would give you 1106rpm.

With a 24T you would get 1660rpm at 100% towards the end of the flight, and 1327rpm at 80% governing.

I agree that a good place to start with headspeed would be around 1200-1250rpm (I run my 4x 600mm Seahawk at 1350rpm, and my 4x 820mm EC-145 at 1050rpm so far).

If you run a 450kV motor, 20T clutch, and 95% governor, you would get 1313rpm, which is probably too fast.

A 350kV motor with a 24T clutch and 95% governor will give you 1226rpm, which is probably closer.

Colin

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )

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05-07-2015 09:49 AM  3 years agoPost 17
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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Andy you are right. I forgot to include this factor in my calculations...

I am looking for a suitable combination to use the 20t clutch as it is significantly cheaper (90 EUR vs 30EUR)...

so a 400 Kv motor would give me 1229 RPM at 100% at the end of the flight... question is if I want to keep it at 100%... probably not as the ESC (I want to use Castle Creations as I have an extra one laying in my spare box) will not like it if I want to govern my headspeed. If I reduce that RPM to 90% I get 1092 which is too low...

450Kv would give me 1382 at 100% and 1228 at 90%...
so I think this is a feasible option?

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05-07-2015 10:09 AM  3 years agoPost 18
Andy01

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Brisbane, Australia

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Running close to 100% is less of an issue for scale as the governor does not need a lot of headspeed when the response times are set to slow, and the changes in load are slow (assuming you plan to fly slow scale circuits rather than sport flying). Castle recommends 95% for sport and 3D to allow the governor to hold the headspeed well.

I would guess that you could probably fly scale at around 98%, so the 400kV option could give you around 1200rpm. The closer to 100% the better for the ESC.

Not much room for margin though

The 450kV might be better although you might find that dropping below 90% can start to generate heat. If you fly in cooler weather though (Australia is pretty warm - a cold winter day is about 17°C or 63°F) you would probably be OK.

Colin

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )

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05-07-2015 07:12 PM  3 years agoPost 19
Mojave

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Palos Verdes, Ca. USA

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Just my .02 I prefer to leave a minimum of 5% head room in the esc (governed down to 95%). 2% is cutting it really close, especially when you really need it...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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05-07-2015 10:00 PM  3 years agoPost 20
goodhunting

rrVeteran

Slovenia ... somewhere in Europe

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well my geographical location does have temperatures above 17deg but most of the year it is around 22 or way below...
I use a similar setup on pod and boom helicopters and stress them with weight and the components (enclosed in the canopy) are not too hot... (my assessment as I can touch them by hand)

I like to keep 10% buffer for governing the HS...
what should the electro motor main shaft diameter be to fit the clutch... 6mm or 8mm?

gh

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