My Sav S throttles

I have been asked to show my throttle setup so here it is.

I used standard GA type throttle controls with solid wire (can push and pull) connected to the throttle torque tube crank on the firewall (drilled an extra hole). From there to the carb connection I used 1/4" CrMo tube tapped out (left hand thread one end) and spherical bearings at each end. This removes the cable problem from the equation and super easy carb balancing.

Most everybody asks "What about the motor movement on startup?" You would think it affects it but I haven't experienced it, it runs extremly smooth and rarely needs adjusting for sync. One installation has over 600 hrs no probs. I also add that this was not my idea. I saw it on a web page ages ago, University of Hawaii Engineering or something. They (students) built a CH701 and didn't like the cables either, so used the rods. I've copied the idea on 3 or 4 aircraft, no probs. Use it if you like, don't if you don't.

Cheers

Rick

Top idea rick. Lot less chance of snapping one of those... I might steal this for my 601 :)

We found these dual throttle cables, designed especially for the dual carburetor 912 series, to be excellent. Very high quality engineered construction. Smooth action, good friction adjustment. Sturdy cables for push-pull security.

Got rid of that crap firewall torque tube contraption, and now carburetors stay in balance forever.... Only have one control knob in the cockpit, but don't need two except for training....

http://www.mcfarlane-aviation.com/Products/?CategoryID=260&ID=76489575&

Also available from Aircraft Spruce.

JG

JG did you mount yours on the left side of the panel or did you shift it towards the centre a bit…also how does it handle the S bend to the righthand carb

I have been asked to show my throttle setup so here it is.I used standard GA type throttle controls with solid wire (can push and pull) connected to the throttle torque tube crank on the firewall (drilled an extra hole). From there to the carb connection I used 1/4" CrMo tube tapped out (left hand thread one end) and spherical bearings at each end. This removes the cable problem from the equation and super easy carb balancing.

Most everybody asks "What about the motor movement on startup?" You would think it affects it but I haven't experienced it, it runs extremly smooth and rarely needs adjusting for sync. One installation has over 600 hrs no probs. I also add that this was not my idea. I saw it on a web page ages ago, University of Hawaii Engineering or something. They (students) built a CH701 and didn't like the cables either, so used the rods. I've copied the idea on 3 or 4 aircraft, no probs. Use it if you like, don't if you don't.

 

Cheers

 

Rick

 

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My only concern with the solid rods would be engine movement on the mount this would shift the rpm a bit I would think…have you done any engine runs yet?

I see you have the rdac unit on the firewall inside the cowl…..what about the heat inside the cowl ? I have mine placed inside the cabin on the right hand side on a bracket I made on two of the inside skin longhorns

JG did you mount yours on the left side of the panel or did you shift it towards the centre a bit…also how does it handle the S bend to the righthand carb

JG

My only concern with the solid rods would be engine movement on the mount this would shift the rpm a bit I would think…have you done any engine runs yet?

The double cables JG suggests are good, but I like to have two throttles, just my preference.

I see you have the rdac unit on the firewall inside the cowl…..what about the heat inside the cowl ? I have mine placed inside the cabin on the right hand side on a bracket I made on two of the inside skin longhorns

Hayden how are things going?..long time no hear

[ATTACH]28907[/ATTACH] Thanks for the inspiration, very happy with the result.

what did you use to make the throttle rods?

[/quote="rotax618, post: 545223, member: 3283]"The problem with a rigid connection betweer the carb and the firewall is the movement of the engine under thrust load, this is particularly bad on the VG bed mount models. I used a bowden cable with a slight kink (the same amount of kink each side) this allows the engine some movement without moving the throttle.

Have you tried it?

I have put these rods on five or six savannahs, bed mount and ring mount and have never had any problems.

I was cautious on the first one (a bed mount), but thought hey I can just go back to Bowden cables. So I made a set and they worked a treat, no vibration problems, and adjusting carb balance is micrometer fine.

We tried straight rods on a VG years ago and found that the forward movement of the engine on the bed mount pulled the throttle back from WOT when the throttle linkage was adjusted to the forward stop when the engine was stopped.

If your system works ! Great.

I have been asked to show my throttle setup so here it is.I used standard GA type throttle controls with solid wire (can push and pull) connected to the throttle torque tube crank on the firewall (drilled an extra hole). From there to the carb connection I used 1/4" CrMo tube tapped out (left hand thread one end) and spherical bearings at each end. This removes the cable problem from the equation and super easy carb balancing.

Most everybody asks "What about the motor movement on startup?" You would think it affects it but I haven't experienced it, it runs extremly smooth and rarely needs adjusting for sync. One installation has over 600 hrs no probs. I also add that this was not my idea. I saw it on a web page ages ago, University of Hawaii Engineering or something. They (students) built a CH701 and didn't like the cables either, so used the rods. I've copied the idea on 3 or 4 aircraft, no probs. Use it if you like, don't if you don't.

 

Cheers

 

Rick

 

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I am going to equip my XL VG with solid rod throttle controls based on your pioneer work using them; I have a couple of questions about the hardware.

With reference to your replies to erd72's thread "Throttle Control", I plan to use a pair of eyeball-type sockets at the firewall (Aircraft Spruce 05-00958 which have the 1/4" hole to fit the outer cable sheath) with a pair of A-820 Friction Lock Controls. (An aside: all three North American Aircraft Spruce warehouses are out-of-stock on the 05-12250 "Cable Safe" items with no information regarding re-stocking. The manufacturer may no longer be in business.)

I already have the R&L hand thread Aurora Stud-type Bearings, the CroMo tubing and the R&L hand thread taps for the rods.

My questions:

• After the eyeball mount is secured on the firewall, is the sphere still free to rotate or is it clamped in a fixed orientation?
   
   
  
• How is the outer cable sheath of the control attached to the eyeball itself - that is to say, what prevents the outer sheath from moving fore and aft through the 1/4" hole in the sphere?
   
   
  
• What was the reason you opted for 6061 aluminum rods for later prototypes instead of staying with the CroMo tubing?
   
   
  

I follow all your posts - along with those of others who have done wonderful things with the Savs - and really appreciate the Recreational Flyer forum.

Regards,

Dan

Hi Rick ,

I think sometime ago you asked me about under carburettors trays , I have found a photo of the good one . Please have a look , I believe you similar not exactly same as accessories from Rotax but a bit expensive.

Hello Rick;I am going to equip my XL VG with solid rod throttle controls based on your pioneer work using them; I have a couple of questions about the hardware.

With reference to your replies to erd72's thread "Throttle Control", I plan to use a pair of eyeball-type sockets at the firewall (Aircraft Spruce 05-00958 which have the 1/4" hole to fit the outer cable sheath) with a pair of A-820 Friction Lock Controls. (An aside: all three North American Aircraft Spruce warehouses are out-of-stock on the 05-12250 "Cable Safe" items with no information regarding re-stocking. The manufacturer may no longer be in business.)

 

I already have the R&L hand thread Aurora Stud-type Bearings, the CroMo tubing and the R&L hand thread taps for the rods.

 

My questions:

 

• After the eyeball mount is secured on the firewall, is the sphere still free to rotate or is it clamped in a fixed orientation?
   
   
  
• How is the outer cable sheath of the control attached to the eyeball itself - that is to say, what prevents the outer sheath from moving fore and aft through the 1/4" hole in the sphere?
   
   
  
• What was the reason you opted for 6061 aluminum rods for later prototypes instead of staying with the CroMo tubing?
   
   
  

 

 

I follow all your posts - along with those of others who have done wonderful things with the Savs - and really appreciate the Recreational Flyer forum.

 

Regards,

 

Dan

1) after the eyeball mount is clamped up the ball is clamped. It is only to get the correct angle on the control cable.

2) the outer sheath is supposed to be clamped up as well when you tighten the eyeball, but I found that it didn't (maybe tolerances on the cable sheath are nominal) so I fixed it by carefully draw filing the flats between the ball halves so it clamped up nice.

3) the only reason was its easier to put a spanner on the hex bar when tightening the locknut. With the Cromo you have to hold it with pliers or vice grips so it ends up looking a bit munted.

When cutting the inner wire to length don't cut it neat to length, leave it long till you're sure. Also don't have the knob right up on the ferrule part at full throttle, always have about 1/2" -1" of s/s rod showing at full throttle so there is no strain point as the engine moves.

Hope it goes well for you.

Cheers

Rick

Hi Rick ,I think sometime ago you asked me about under carburettors trays , I have found a photo of the good one . Please have a look , I believe you similar not exactly same as accessories from Rotax but a bit expensive.

Those ones look like they would suffer from engine shake, looks like there's maybe been a crack repair where the flange bend is. (See the short weld)

The rotax ones have a continuous curve from the flange so they are rigid with no fatigue point. Only problem is you got to take the carb off to check the bowls, pain in the a$$.

Yes I agree, well spotted. I have different on my plane, not so pretty but functional they are flatter and supported from underneth from exhaust pipe which is directly under the carburator. This the whole idea to shield carby from hot pipe and possible fuel leak catchment.

Hi Dan,1) after the eyeball mount is clamped up the ball is clamped. It is only to get the correct angle on the control cable.

2) the outer sheath is supposed to be clamped up as well when you tighten the eyeball, but I found that it didn't (maybe tolerances on the cable sheath are nominal) so I fixed it by carefully draw filing the flats between the ball halves so it clamped up nice.

 

3) the only reason was its easier to put a spanner on the hex bar when tightening the locknut. With the Cromo you have to hold it with pliers or vice grips so it ends up looking a bit munted.

 

When cutting the inner wire to length don't cut it neat to length, leave it long till you're sure. Also don't have the knob right up on the ferrule part at full throttle, always have about 1/2" -1" of s/s rod showing at full throttle so there is no strain point as the engine moves.

 

Hope it goes well for you.

 

Cheers

 

Rick

As you may surmise if you read the thread I started yesterday about undercarriage issues, it will be a few months before the throttle project is completed. When it is completed, I'll post some photos.

Fly safely,

Dan

I have been asked to show my throttle setup so here it is.I used standard GA type throttle controls with solid wire (can push and pull) connected to the throttle torque tube crank on the firewall (drilled an extra hole). From there to the carb connection I used 1/4" CrMo tube tapped out (left hand thread one end) and spherical bearings at each end. This removes the cable problem from the equation and super easy carb balancing.

Most everybody asks "What about the motor movement on startup?" You would think it affects it but I haven't experienced it, it runs extremly smooth and rarely needs adjusting for sync. One installation has over 600 hrs no probs. I also add that this was not my idea. I saw it on a web page ages ago, University of Hawaii Engineering or something. They (students) built a CH701 and didn't like the cables either, so used the rods. I've copied the idea on 3 or 4 aircraft, no probs. Use it if you like, don't if you don't.

 

Cheers

 

Rick

 

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Savannah carb balance is really instable, i would like to convert like you done. Is it possible to have drawing detail or Spherical bearings reference you use ? Did you make some modification on the Throttle linkage (Diameter hole or other)?

THanks in advance for your Help !

Eric

Hi Eric

I regret to inform you that Rick passed away earlier this year. Ricks mods I spoke to him about and they are just normal ball links I think they were 4mm or 6mm holes in the ball links

Hi Kyle,

Really sad this to read that... I just had a look on the post concerning Rick...

Thank you for the ball link description.