RC Jets Discuss RC jets in this forum plus rc turbines and ducted fan power systems

$1,000.00 bounty offered to fix COMP ARF A4 steering

Reply
Old 09-30-2012, 12:46 PM
  #1
AndyAndrews
Thread Starter
 
AndyAndrews's Avatar
 
Join Date: Feb 2007
Location: Little Rock, AR
Posts: 5,995
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default $1,000.00 bounty offered to fix COMP ARF A4 steering

Ok you engineering geniuses. I will pay $1,000.00 cash to the first person who can find a way to make the COMP ARF A4 nose gear steer reliably and maintain it's scale appearance. This offer is reliant on being able to do this quickly. Like in the next two months. Moreover, the solution cannot be exceedingly heavy. See this thread for more info: http://www.rcuniverse.com/forum/m_10225819/tm.htm

Any takers call email me: aa@foodserviceequipment.com
AndyAndrews is offline  
Reply With Quote
Old 09-30-2012, 01:35 PM
  #2
BaldEagel
 
BaldEagel's Avatar
 
Join Date: Oct 2005
Location: Kent, UNITED KINGDOM
Posts: 9,635
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Put a gyro on it.

Mike
BaldEagel is offline  
Reply With Quote
Old 09-30-2012, 01:45 PM
  #3
GSR
 
Join Date: Oct 2002
Location: Seal Beach, CA
Posts: 1,920
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

I think they already did that about 7 times. S
GSR is offline  
Reply With Quote
Old 09-30-2012, 01:54 PM
  #4
Dr Honda
 
Dr Honda's Avatar
 
Join Date: Apr 2005
Location: Latrobe, PA
Posts: 2,221
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

OK... I don't feel like reading a build thread... so...

1) what's wrong with it?

2) What is it doing?

3) What's your thoughts on a fix?

I own a machine shop, and I make RC parts for a few shops, and, a few under my own label. I would be glad to give it a look over. My main focus are motorcycles... so I will be entering my slow time of the year very soon.

Since the gear comes with the model... I would rather make a retro-fix, rather than to make an entirely new nose gear. So... If you want to send me a nose gear... I'll see what I can do.
Dr Honda is offline  
Reply With Quote
Old 09-30-2012, 02:26 PM
  #5
Boomerang1
 
Boomerang1's Avatar
 
Join Date: Jun 2005
Location: Sydney, AUSTRALIA
Posts: 2,827
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Quote:
So... If you want to send me a nose gear... I'll see what I can do.
Andy's offering 2 grand on his other thread, I'd fix it over there!

Seriously, contact Peter Agnew from Intairco. Like David Gladwin says I know him
to be a guy who has to have things just right & if he's familiar with the retract
anyway he'd be my go-to guy. My opinion? A new leg with the pivot at the top at
the trunion & a dummy steering cylinder on the bottom. - John.
Boomerang1 is offline  
Reply With Quote
Old 09-30-2012, 02:51 PM
  #6
jetpilot
 
jetpilot's Avatar
 
Join Date: Dec 2001
Location: Allen, TX
Posts: 2,967
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Ive got two sets that need fixing!! Im in!!
Scott
jetpilot is offline  
Reply With Quote
Old 09-30-2012, 03:35 PM
  #7
George
 
George's Avatar
 
Join Date: Dec 2001
Location: Va Beach, VA
Posts: 2,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering


Quote:
ORIGINAL: jetpilot

Ive got two sets that need fixing!! Im in!!
Scott
Scott,

If you want to send me one, I'll work on a solution. Are you going to BITW? I have to stop in Dallas, so I'll be driving through Texas on my way to Cali.

George is offline  
Reply With Quote
Old 09-30-2012, 04:27 PM
  #8
Canukk
 
Join Date: Apr 2012
Location: Bedford, TX
Posts: 14
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Make the arm on the gear longer so it doesn't have to work so hard and can be more precise.

It looks very short.
Canukk is offline  
Reply With Quote
Old 09-30-2012, 04:36 PM
  #9
bcovish
 
bcovish's Avatar
 
Join Date: Feb 2002
Location: Austin, TX
Posts: 5,138
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering


Quote:
ORIGINAL: George


Quote:
ORIGINAL: jetpilot

Ive got two sets that need fixing!! Im in!!
Scott
Scott,

If you want to send me one, I'll work on a solution. Are you going to BITW? I have to stop in Dallas, so I'll be driving through Texas on my way to Cali.

George, I'll be driving Scott's stuff and will be leaving from Dallas. Sent you a pm
Attached Thumbnails
Click image for larger version

Name:	Ay74161.jpg
Views:	15
Size:	84.9 KB
ID:	1806531  
bcovish is offline  
Reply With Quote
Old 09-30-2012, 04:38 PM
  #10
bcovish
 
bcovish's Avatar
 
Join Date: Feb 2002
Location: Austin, TX
Posts: 5,138
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Now back to the regular scheduled thread. Sorry Andy
bcovish is offline  
Reply With Quote
Old 09-30-2012, 06:40 PM
  #11
AndyAndrews
Thread Starter
 
AndyAndrews's Avatar
 
Join Date: Feb 2007
Location: Little Rock, AR
Posts: 5,995
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

No worries Bob, Scott and I are in the same boat looking for a solution. I've got someone working on it right now. Lets see what comes out of it. Thanks for all of the PM's. If I can't get this thing sorted out I'm sure I'll be knocking.
AndyAndrews is offline  
Reply With Quote
Old 09-30-2012, 06:42 PM
  #12
AndyAndrews
Thread Starter
 
AndyAndrews's Avatar
 
Join Date: Feb 2007
Location: Little Rock, AR
Posts: 5,995
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering


Quote:
ORIGINAL: Boomerang1

Quote:
So... If you want to send me a nose gear... I'll see what I can do.
Andy's offering 2 grand on his other thread, I'd fix it over there!

Seriously, contact Peter Agnew from Intairco. Like David Gladwin says I know him
to be a guy who has to have things just right & if he's familiar with the retract
anyway he'd be my go-to guy. My opinion? A new leg with the pivot at the top at
the trunion & a dummy steering cylinder on the bottom. - John.
That won't work. The wheel is offset from the strut. Also, the strut has to be able to extend.
AndyAndrews is offline  
Reply With Quote
Old 09-30-2012, 06:52 PM
  #13
shepp
 
Join Date: Jan 2004
Location: Goodlettsville, TN
Posts: 416
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Andy,
have you considered replacing the pneumatic system with Hydraulic, Use a servo to drive an air cylinder, that has been converted to hydraulic, then run lines to cylinder on steering arm. Closed system void of all air. Still need the lines to the steering cylinder, but would give positive response. Just a thought.

Glenn (Scotty's friend)
shepp is offline  
Reply With Quote
Old 09-30-2012, 06:57 PM
  #14
jonty
 
jonty's Avatar
 
Join Date: Jun 2006
Location: , NEW ZEALAND
Posts: 68
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Hi guys

There is a guy in NZ with a 1:5 scale A4 with a fully hydralic nose gear set up. Not sure if it has flown yet but pics are attached. I can get you an email address if interested
Attached Thumbnails
Click image for larger version

Name:	Ge95220.jpg
Views:	24
Size:	20.3 KB
ID:	1806617   Click image for larger version

Name:	Ke91904.jpg
Views:	17
Size:	24.8 KB
ID:	1806618  
jonty is offline  
Reply With Quote
Old 09-30-2012, 07:38 PM
  #15
AndyAndrews
Thread Starter
 
AndyAndrews's Avatar
 
Join Date: Feb 2007
Location: Little Rock, AR
Posts: 5,995
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering


Quote:
ORIGINAL: shepp

Andy,
have you considered replacing the pneumatic system with Hydraulic, Use a servo to drive an air cylinder, that has been converted to hydraulic, then run lines to cylinder on steering arm. Closed system void of all air. Still need the lines to the steering cylinder, but would give positive response. Just a thought.

Glenn (Scotty's friend)
Hey Glenn,

The system is Hydraulic not pneumatic.

Andy
AndyAndrews is offline  
Reply With Quote
Old 09-30-2012, 07:46 PM
  #16
AndyAndrews
Thread Starter
 
AndyAndrews's Avatar
 
Join Date: Feb 2007
Location: Little Rock, AR
Posts: 5,995
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering


Quote:
ORIGINAL: Dr Honda

OK... I don't feel like reading a build thread... so...

1) what's wrong with it?

2) What is it doing?

3) What's your thoughts on a fix?

I own a machine shop, and I make RC parts for a few shops, and, a few under my own label. I would be glad to give it a look over. My main focus are motorcycles... so I will be entering my slow time of the year very soon.

Since the gear comes with the model... I would rather make a retro-fix, rather than to make an entirely new nose gear. So... If you want to send me a nose gear... I'll see what I can do.
1-2.) the system leaks, doesn't move the nose gear properly, won't center, requires too much force to move and when it does it only moves 1/2 of the time. There is no way to bleed the air.
3. ) replace with closed system with a pump, cylinder block type system or improve on the cylinders provided. I need a system that won't leak causing air bubbles.

I guess my post drew some attention. Thanks for offering to help.

Andy
Attached Thumbnails
Click image for larger version

Name:	Ge96187.jpg
Views:	20
Size:	116.7 KB
ID:	1806666   Click image for larger version

Name:	Ws56808.jpg
Views:	19
Size:	93.1 KB
ID:	1806667  
AndyAndrews is offline  
Reply With Quote
Old 09-30-2012, 08:34 PM
  #17
kiwijet
 
Join Date: Feb 2003
Location: Palmerston North, NEW ZEALAND
Posts: 92
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Hi Andy,

I'm the guy in NZ that "jonty" is refering to above with the 1/5th A4 (Skymaster) AUW approx 35lbs.

It uses the Likai retracts and steering system and works smooth as silk. It is a "closed loop" hydraulic system with equal capacity rams, one mounted down at the steering point and another single ram (not twin like your ones) being driven by a JR 8511 servo. I believe both cyl need to be of equal size to get accurate, smooth easy steering.

There is no bleed point on these rams the secret is to submerge both chylinders and their respective fluid line nipples in a bath of hyd fluid (we use air tool lube oil) the rams are first purged of air independantly by exercising them back and forth, then each line is filled with fluid and purged all the while keeping the entire system submerged in the oil bath especially when connecting the purged oil lines back onto their respective nipples.

It's also important to ensure both rams are centred in relationship to each other when connecting the system to ensure equal and full steering in both directions.
Bit of a messy process but secret is keeping all inlet/outlet points submerged whilst carrying this out.

Do this.....and it works! hope it helps!
kiwijet is offline  
Reply With Quote
Old 09-30-2012, 08:53 PM
  #18
just because
 
Join Date: Sep 2012
Location: , TX
Posts: 5
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

HI I am a new member to rcu. could you install a bleeder in the cylinders . maybe a presure tap from a two stroke muffler. to bleed all youwould need would be a small syringe
tosuck the fluid.
just because is offline  
Reply With Quote
Old 09-30-2012, 08:59 PM
  #19
mr_matt
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 9,915
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

From my comp arf hydraulic experience you have to devise a way to bleed them 100%. And I think a larger diameter master cylinder would help but I am not sure. Also I don't know why you need 2 cylinders, seems like you could connect it up to one master cylinder with the whole shooting match sealed. Who knows it is late!

EDIT: what I mean is connect one side of the steering ram to one side of the servo driven ram, and then the other side likewise. Not sure what a different diameter on the driven side would do but it is worth a try and that way you can't get air in if it leaks across the piston(s).
mr_matt is offline  
Reply With Quote
Old 09-30-2012, 11:37 PM
  #20
olnico
 
olnico's Avatar
 
Join Date: May 2007
Location: Houston, Texas.
Posts: 3,710
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Looking at the pictures ( bear in mind that I do not have the dimensions of the system ) it could be that a Firgelli L12-30 linear actuator would work in that application.
http://www.firgelli.com/Uploads/L12_datasheet.pdf
Essentially this actuator provides 30 mm of stroke at a speed of 23 mm/sec max, a max actuation force of around 10 N in practice or 2,2 lb-force in the 1:50 gearing option. The overall length of the actuator is 90 mm between the attachment points when retracted and 120 mm extended.
L12-30R series have an integrated controller and servo plug input. Compatible with standard Futaba 1-2 ms 5V command signal.

The 10 mm stroke actuator might be available for this application in the -P version. This actuator has a dimension of 70 mm retracted and 80 mm extended. The -P version means that it has to be controlled by the external LAC controller ( see below ). This would have to be confirmed by the factory.
Price 80 USD


If the L12 series is too big, you have the PQ12.
http://www.firgelli.com/Uploads/PQ12_datasheet.pdf
It has a length of 45 mm retracted and 65 mm extended. Stroke 20 mm but the max force at 23 mm/sec gearing is lower: about 5N or 1,1 Lb-force.
Also it is more "plastic-like" and might not sustain the working conditions for a long time.
Price 65 USD

These actuators are easy to drive with their LAC control board that has a 1-2 ms 5V standard Futaba RC input.
http://www.firgelli.com/Uploads/LAC_Datasheet.pdf
Price 40 USD


http://store.firgelli.com/category_s/1826.htm

Note that these products are also fairly nice for gear door actuation...
olnico is offline  
Reply With Quote
Old 10-01-2012, 05:25 AM
  #21
kirkj
 
Join Date: Sep 2002
Location: spring, TX
Posts: 455
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

OK..... here is the fix. from a fluid power systems engineer (me)

only use 1 cylinder on the servo end - not two.
bleed both cylinders very well. submerge the bare cylinders in a bowl of oil, reach in and stroke them till no air comes out.
before you pull them from the oil bowl... retract one cylinder completely - and extend one cylinder completely.
leave the cylinders positioned this way. take great pains to not compress or extend them.
(you can use vegtable oil if you want.)
install the master and slave cylinders on the servo and gear leg.
bleed your lines the same way in a bowl, and fish them thru the leg, and hook them up.
VERY IMPORTANT... hook 1 line from the rod side of the master to the rod side of the slave. and from the blind side of the master to the blind side of the slave.

clean up oil , and enjoy.

when you now center the master, the slave will center, and so on.
Kirk
kirkj is offline  
Reply With Quote
Old 10-01-2012, 05:35 AM
  #22
Lance Campbell
 
Lance Campbell's Avatar
 
Join Date: Oct 2002
Location: Columbia, MO,
Posts: 186
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

I'm liking Oli's train of thought. You need such fidelity of control on a nose gear to be very precice with it. I'm thinking about how little we move the nose gear steering on the high speed element of the take off / landing routine, and can't see the cylinder doing that.

Lance
Lance Campbell is offline  
Reply With Quote
Old 10-01-2012, 05:46 AM
  #23
olnico
 
olnico's Avatar
 
Join Date: May 2007
Location: Houston, Texas.
Posts: 3,710
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Yes, the Firgelli actuators have 0,1 mm of slack. Pretty much unbeatable.
The problem is to ensure that 1 lb-torque at approx. 15 mm/s is enough on a 20 mm travel.

I think that the only way to find out is to order a PQ12 and a L12-30 and try both solutions in-situ.

The problem with the hydraulic solution is the amount of elongation the system will take before the piston actually starts moving. This is mostly due to the elastic nature of the plastic tubing used. When the hydraulic fluid transmits the pressure from the command piston, the lines expand a bit and that creates some sort of hysteresis in the piston motion. Very difficult to control, especially considering the fact that the tubing elastic point is varying with the outside temperature...
olnico is offline  
Reply With Quote
Old 10-01-2012, 05:54 AM
  #24
invertmast
 
invertmast's Avatar
 
Join Date: Dec 2003
Location: North Port, Fl
Posts: 7,645
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering

Oli,
The firgelli actuator was what i was thinking of late night last night as well. I think the problem with those will be the size, after seeing a photo of the slave cylinder mounted on the nose gear, it appears to have very little space between it and the strut.

For the price though, they are still worth a shot
invertmast is offline  
Reply With Quote
Old 10-01-2012, 06:04 AM
  #25
olnico
 
olnico's Avatar
 
Join Date: May 2007
Location: Houston, Texas.
Posts: 3,710
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: $1,000.00 bounty offered to fix COMP ARF A4 steering


Quote:
ORIGINAL: invertmast

Oli,
The firgelli actuator was what i was thinking of late night last night as well. I think the problem with those will be the size, after seeing a photo of the slave cylinder mounted on the nose gear, it appears to have very little space between it and the strut.

For the price though, they are still worth a shot
Yep Thomas.
I think it's worth spending a few bucks to give it a try.
These are also worth considering for your F-14 in specific applications like speedbrakes, some doors etc...
olnico is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 04:01 AM.