Simple / Clean 4#3B Bell/Hiller mod - RC Groups
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Dec 24, 2008, 07:23 PM
Designer
superdave42's Avatar
Cool

Simple / Clean 4#3B Bell/Hiller mod


When I first got my 4#3A I instantly liked it. it flew very well for being so small. Then the never ending urge to MODIFY suddenly took over.

I wanted faster response.

I wanted more agility

I wanted it to look fast standing still.

I just wanted to be different..

I am not the first person to do this mod on a 4#3, EQMOD and some others have done this as well. I just wanted to make it all out of off the shelf Walkera parts.


So I extended the tail by .5" and installed the 4G3 tail assembly.

Installed some Tuff struts (which looked very funny until I modified them, gave it the rake angle).

Swash support.

Blue -Q grips

Bell/Hiller Mod:

This mod worked out very nicely, gave me exactly the level of response that I had imagined it would.

My first goal was to make it all work with off-the-shelf parts.

it basically consists of:

1. Mixer arm (from 4G3)
2. Mixer arm shoulder screw (from 4G3, needs to be cut in length)
3. Linkages (made from 2nd set of 4#3 dog bones cut 30% off, 4G#3 plastic ball link, the connecting tube is a cut stock ball link shank)
4. Flybar linkage ( stock 4#3)

it's very simple and instantly gratifying.

Pretty much has the cyclic response of the 4G3 now. only tested so far in my living room because it's storming outside.

I'm sure the geometry is not perfect, but it does have a totally different feel now.

Dave
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Dec 24, 2008, 07:27 PM
Registered User
Video please. In flight and mechanical movements.
Dec 25, 2008, 08:34 PM
Registered User
EQMOD's Avatar
Great mod! Any flight video ?

For best results you need to keep those mixing arms on both side parallel with one another.
Dec 25, 2008, 09:02 PM
that's gonna leave a scar
KCinNC's Avatar
nice job man !!
Dec 25, 2008, 09:03 PM
Designer
superdave42's Avatar
Quote:
Originally Posted by EQMOD
Great mod! Any flight video ?

For best results you need to keep those mixing arms on both side parallel with one another.
Thanks eqmod.

I know ideally you want paralell and 90 degrees. But this is what you get using the stock flybar linkage and it works fine. I think this little heli has a few compromises out of the box. This I'm sure most will consider a compromise as well. Anyone with B grips can try this quite easilly.

I'll try to get a flight video. It really us night and day difference.
Dec 26, 2008, 04:47 PM
Designer
superdave42's Avatar
Some short video
4#3B bell-hiller mod 1 (0 min 44 sec)


4#3B bell-hiller mod 2 (0 min 12 sec)


4#3B bell-hiller control (0 min 16 sec)
Dec 30, 2008, 05:48 AM
flying beam
blackmoon's Avatar
Hi,

In your video, are you giving some quick and crisp cyclics to test it?

Because it seems rather unstable.

Thank you.

P.
Dec 30, 2008, 01:50 PM
Designer
superdave42's Avatar
Quote:
Originally Posted by blackmoon
Hi,

In your video, are you giving some quick and crisp cyclics to test it?

Because it seems rather unstable.

Thank you.

P.
Yes in all the videos I am giving fast side to side and front to back stick movements, just to show that the cyclic is much faster now. that Hiller lag is definitely gone now.
Dec 30, 2008, 02:02 PM
flying beam
blackmoon's Avatar
Quote:
Originally Posted by superdave42
Yes in all the videos I am giving fast side to side and front to back stick movements, just to show that the cyclic is much faster now. that Hiller lag is definitely gone now.
Thank you.

Paulo.
Jan 03, 2009, 03:03 PM
Registered User
Dave,

I have now made the exact same mod on my 4#3b, the difference in flying is amazing.
It's like night and day, shame I broke the pin that holds the tail rotor.... doh
Jan 03, 2009, 03:23 PM
Designer
superdave42's Avatar
Quote:
Originally Posted by kermitthefrog
Dave,

I have now made the exact same mod on my 4#3b, the difference in flying is amazing.
It's like night and day, shame I broke the pin that holds the tail rotor.... doh

Hi, glad it worked for you :-) I love it.

I have been pondering making different ratio arms now. looks like the ratio is 2:1 currently and I might try 1.5:1 and 1:1 and see if it gets even better.


if you still have your tail skid rod,, you can use that as a rotor shaft until you get a new one :-)

Dave
Jan 03, 2009, 03:57 PM
Registered User
Quote:
Originally Posted by superdave42
Hi, glad it worked for you :-) I love it.

I have been pondering making different ratio arms now. looks like the ratio is 2:1 currently and I might try 1.5:1 and 1:1 and see if it gets even better.


if you still have your tail skid rod,, you can use that as a rotor shaft until you get a new one :-)

Dave

Thanks for the trick to fix my tail rotor.

Regarding the length of the rods in the BH mod, I guess they have to be the same length, is that right?
Jan 07, 2009, 04:52 PM
Designer
superdave42's Avatar
Quote:
Originally Posted by kermitthefrog
Thanks for the trick to fix my tail rotor.

Regarding the length of the rods in the BH mod, I guess they have to be the same length, is that right?

cool.

yes the rods need to be matched length.
Jan 07, 2009, 04:53 PM
Designer
superdave42's Avatar

Backasswards


I just realized that all of us that are using the 4G3 mixer arm to perform this mod have the bell/hiller ratio BACKWARDS lol I think it was because the parts just fit better this way. but in reallity what we really want is to have the the Flybar give more input than the swashplate.. like all the other normal B/H mechanics..

hehe yeah it works, but we may just find the flight more enjoyable with the correct ratio allocation.

anyways, not sure if anyone thought about this, I sure did not.

with the correct ratio the flybar will work better and then still allow the direct swash input to help get things going.

hehe.

Dave
Jan 07, 2009, 05:11 PM
Registered User
Air Vaca's Avatar
looks like you have the flybar with more authority. The swash to mixer has to move further to have affect. A fixed length will cover more degrees of a smaller circle.
Bill


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