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CARF F4U-1 Corsair build thread

Old 06-03-2013, 11:42 PM
  #2076  
ram3500-RCU
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Default RE: CARF F4U-1 Corsair build thread

Couple more shots. If you do the hinges correctly, slightly more than 90 deg is possible when open. Plenty of access to the controls within.
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Old 06-04-2013, 12:00 AM
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Default RE: CARF F4U-1 Corsair build thread

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Old 06-04-2013, 12:05 AM
  #2078  
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: ram3500-RCU

Switches top and bottom. The 9V battery was for the old gun system. No longer used. The new system is completely different, and uses (24) AA batteries in three 8 battery holders that are placed in the leading edge of the center section.
Hi Ram, if you don't mind me asking. What did you use for the white tape to cover the fuel tank joins? I need to do mine, only reason I haven't is I have not found the right material to use.

Regards

JAM
Old 06-04-2013, 01:57 AM
  #2079  
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Default RE: CARF F4U-1 Corsair build thread

Gary,
Very cool gas cap hatch.
Old 06-04-2013, 04:15 AM
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John Taylor
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Default RE: CARF F4U-1 Corsair build thread

Gary Happy B-day to you and many more. JB
Old 06-04-2013, 01:22 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: stivvy

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Hello Steve.

(1) Yes, the rudder is removable. It slides over the carbon fiber torque rod, and down onto a tiller rod that is through the carbon rod. Only two screws hold it is place from the top, hidden under the balance nose area of the rudder. Very good design.

(2) Yes again. You can and do drill and tap the carbon fiber torque rod. It holds threads very well and the bolts stay tight in it. This works very well. Trick is to get the two elevators lines up perfectly straight when you drill and tap the rod. In the kit, they give you two rods just in case you screw one up. I always go very slow on this operation and use a jig to hold the two elevators in line with each other. Now if you are separating the elevators and using two servos, no big deal. I prefer not to, and use one strong and very high quality servo. A JR 8711 is my choice.

Old 06-04-2013, 01:25 PM
  #2082  
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: samparfitt

Gary,
Very cool gas cap hatch.
Thank you Sam. It works very well and looks scale. I try not to do non scale hatches, or at least hatches in non scale sizes and locations. The fuel tank cover of the Corsair makes a perfect hatch for all you need and is easy to get to.
Old 06-04-2013, 01:26 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: John Taylor

Gary Happy B-day to you and many more. JB
60 and still playing with toys.
Old 06-04-2013, 01:30 PM
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Default RE: CARF F4U-1 Corsair build thread

Happy bday Gary!

Wishing you many more!

Casey
Old 06-04-2013, 01:42 PM
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Default RE: CARF F4U-1 Corsair build thread


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Happy bday Gary!

Wishing you many more!

Casey
Probably gone a take my a few more to get all these planes built.
Old 06-04-2013, 01:43 PM
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Default RE: CARF F4U-1 Corsair build thread

Thanks guys.

The big deal for me this year is that my wife and I will have been married for 40 years this coming August. Love that gal. Wish she shared my passion for aviation, but allas, she is an animal loving ground hugger.
Old 06-04-2013, 01:49 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: ram3500-RCU


ORIGINAL: John Taylor

Gary Happy B-day to you and many more. JB
60 and still playing with toys.

It is well known the only difference between men and boys is the price of their toys
Last week our 82 year old visitor flew his Moki powered Tempest. At sixty you are only just getting going

best wishes
Ed
Old 06-04-2013, 02:59 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: Edhamp


ORIGINAL: ram3500-RCU


ORIGINAL: John Taylor

Gary Happy B-day to you and many more. JB
60 and still playing with toys.

It is well known the only difference between men and boys is the price of their toys
Last week our 82 year old visitor flew his Moki powered Tempest. At sixty you are only just getting going

best wishes
Ed
Thanks Ed. Of course, as usual, you are absolutely correct.

I hope my best work is yet in front of me, and wish that for all my building friends.
Old 06-04-2013, 10:44 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: ram3500-RCU


ORIGINAL: stivvy

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Hello Steve.

(1) Yes, the rudder is removable. It slides over the carbon fiber torque rod, and down onto a tiller rod that is through the carbon rod. Only two screws hold it is place from the top, hidden under the balance nose area of the rudder. Very good design.

(2) Yes again. You can and do drill and tap the carbon fiber torque rod. It holds threads very well and the bolts stay tight in it. This works very well. Trick is to get the two elevators lines up perfectly straight when you drill and tap the rod. In the kit, they give you two rods just in case you screw one up. I always go very slow on this operation and use a jig to hold the two elevators in line with each other. Now if you are separating the elevators and using two servos, no big deal. I prefer not to, and use one strong and very high quality servo. A JR 8711 is my choice.

Thanks Gary,

I will have a look at the rudder tonight as I still cant quite get my head around it.

Cheers

Steve D
Old 06-04-2013, 11:22 PM
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STAN-CAUSSEL
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: stivvy

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Hello Steve
Here is the solution I choose for my elevators. Considering that for me it is a necessity to remove the elevators for transportation.
Best regards
Stan
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Old 06-05-2013, 02:12 PM
  #2091  
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Default RE: CARF F4U-1 Corsair build thread

ORIGINAL: STAN-CAUSSEL


ORIGINAL: stivvy

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Hello Steve
Here is the solution I choose for my elevators. Considering that for me it is a necessity to remove the elevators for transportation.
Best regards
Stan
Very creative Stan, and very good use of leverage from the servo for torque on the elevator. Nice work on the balance tabs as well.
Old 06-05-2013, 02:15 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: stivvy


ORIGINAL: ram3500-RCU


ORIGINAL: stivvy

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Hello Steve.

(1) Yes, the rudder is removable. It slides over the carbon fiber torque rod, and down onto a tiller rod that is through the carbon rod. Only two screws hold it is place from the top, hidden under the balance nose area of the rudder. Very good design.

(2) Yes again. You can and do drill and tap the carbon fiber torque rod. It holds threads very well and the bolts stay tight in it. This works very well. Trick is to get the two elevators lines up perfectly straight when you drill and tap the rod. In the kit, they give you two rods just in case you screw one up. I always go very slow on this operation and use a jig to hold the two elevators in line with each other. Now if you are separating the elevators and using two servos, no big deal. I prefer not to, and use one strong and very high quality servo. A JR 8711 is my choice.

Thanks Gary,

I will have a look at the rudder tonight as I still cant quite get my head around it.

Cheers

Steve D
I tried to post some pictures Steve. I'll try again. It is really very simple once you see it. It will make perfect sense to you.

This is the torque rod for the rudder from inside.
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Old 06-05-2013, 02:18 PM
  #2093  
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Default RE: CARF F4U-1 Corsair build thread

This is the same rod from the top (plane is sitting on it's side). The rudder slides onto it and there is a slot in the bottom of the rudder that the 'tiller' bar fits in. This is how the rudder is driven. Two screws hold it down on the tiller from the top.

0 slop in the rudder. Very positive control, and yet completely removable. Nice for painting.
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Old 06-05-2013, 02:41 PM
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Default RE: CARF F4U-1 Corsair build thread

Here is a link to a video I had made on the top hatch.

http://www.youtube.com/watch?v=49hub3Gtlws
Old 06-06-2013, 09:44 AM
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Default RE: CARF F4U-1 Corsair build thread

Gary,
Looking at the pictures of your linkage and servo setup for rudder and elevator... May I suggest that you move the ball links on your servo arms towards the center of the servo as far as you can get them. You have poor mechanical advantage for the servo with them located as shown for both elevator and rudder. I have a CompArf F4U as well and have no problem getting the recommended travel on these surfaces with them installed at the closest hole to the center of the servo. You'll have more power to drive the surface, better centering, and less slop.

I also see that you soldered the brass tubes that act as spacers to the larger brass tube that collars the carbon pivot rod. I didn't see this in the manual, is it something that you came up with? Interesting idea. Did you do the same on the elevator? What prompted you to do this?

Thanks for your informative posts.

KennyMac

PS, the exhaust tips are working great so far!
Old 06-06-2013, 10:46 AM
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Default RE: CARF F4U-1 Corsair build thread

Kenny,
good point: I'm guilty of doing that, myself as I usually make the length of the control horn the same as the servo arm.

Another nice side effect of this is using the full travel of the control stick and thus, reducing sensitivity and needing to use a lot of expo.

Although the reverse of what we want as Archimedes once said, “Give me a place to stand and I will move the world."

Horizon's website explains it clearly:

http://www.horizonhobby.com/article/...ical-advantage

Mechanical Advantage is a very important concept when setting-up linkages - especially with larger aircraft. It refers to the leverage that the servo can exert on the control surface. Since the control surfaces are rather large it is important for the servo to have enough mechanical advantage or leverage to control them, regardless of the servo's rated torque. A large amount of torque is of little value if there is not enough leverage to use it. Insufficient leverage can lead to control surface flutter (usually a catastrophic event) and blow-back, where the air flow pushes the control surface backwards resulting in mushy or no control at higher speeds.

There are two ways to increase the mechanical advantage of the servo. One is to make sure that the control horn device is long enough, whether it be a horn as shown in the illustration above or a bolt with a Rocket City-type fastener. The horn is the lever that the servo uses to control the surface. The longer the horn, the more leverage the servo has. It's like a lug wrench - when you can't get a lug nut loose you put a piece of pipe over the end of the lug wrench to extend the handle and that gives you more leverage to break the lug nut free. It's the same thing - the lug nut is the control surface and you are the servo trying to move it. As a general rule-of-thumb, try to attach the linkage at the control surface so that it is at least 1" away from the surface - longer is better.

The second way to increase the mechanical advantage for the servo is to attach the linkage at the servo arm as far inward (towards the servo arm retaining screw) as possible while still providing enough throw. It's the "lever thing" again, but in reverse, as we are trying to take leverage away from the control surface by providing it with a shorter lever to work against the servo.
Old 06-06-2013, 06:16 PM
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Default RE: CARF F4U-1 Corsair build thread

The explanation of torque and leverage are very good. Thank you Sam. Good stuff. Something we all need to always consider when setting up any control system, much less giant scale like this.

In the case of the rudder on the CARF set up, I found the geometry, as shown in the manual to cause binding if the rods were not parallel, and a rod connected too close to the hinge point on a large rudder is also a possible flutter waiting to happen, because you are reducing the leverage, as noted above. If you had only one side pushing / pulling, yes, but not with a duel setup such as this.

The JR 8711, my choice for this location, has 403 oz of torque. A 1" distance from the center of the arm is a very conservative distance for this powerful servo. It may look like more in the picture, but that is all it is. Plus, the large rudder of the Corsair has a balance driver on the front of it, helping.

The setup, as CARF has designed it, has NO slop. The torque rod has equal force on it at all times. Because of the way it is designed to be supported in the bearings, it needs to be driven by these two rods. The result, very positive control.
Old 06-06-2013, 06:35 PM
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Default RE: CARF F4U-1 Corsair build thread

ORIGINAL: GR7Racer

Gary,
Looking at the pictures of your linkage and servo setup for rudder and elevator... May I suggest that you move the ball links on your servo arms towards the center of the servo as far as you can get them. You have poor mechanical advantage for the servo with them located as shown for both elevator and rudder. I have a CompArf F4U as well and have no problem getting the recommended travel on these surfaces with them installed at the closest hole to the center of the servo. You'll have more power to drive the surface, better centering, and less slop.

I also see that you soldered the brass tubes that act as spacers to the larger brass tube that collars the carbon pivot rod. I didn't see this in the manual, is it something that you came up with? Interesting idea. Did you do the same on the elevator? What prompted you to do this?

Thanks for your informative posts.

KennyMac

PS, the exhaust tips are working great so far!
Thanks Kenny. Glad the pipes are doing the trick. We have gotten nothing but good feedback on them.

Thanks for the suggestions on the rigging. Your observations are always welcome.

As for the drive yoke for the rudder, yes, I don't like relying on all thread in a torque situation like this, on such a large airplane. Brass sleeves slid on the all thread add no strength to the system IMO. I drill a slightly larger hole in the rod and sleeve, slide the brass tube through and solder it to the outside sleeve. This is cut to the proper length so the ball links can be tightened against it on the all thread. Just my thing I guess.
Old 06-06-2013, 10:34 PM
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Default RE: CARF F4U-1 Corsair build thread


ORIGINAL: STAN-CAUSSEL


ORIGINAL: stivvy

Hi Gary,

Seeing as how you are up and at it this morning, I have a couple of issues that I cannot get straight in my head.

(1) Rudder - the CARF instructions say that once the fin and rudder assembly is fitted, the torque rod remains permanently installed but the rudder can still be removed for maintenance. Is this correct as it seems to be a permanent installation to me.

(2) Elevators - the CARF instructions say drill and tap the torque rod where the elevators will be secured - am I right in thinking that you tap the carbon ? Never tapped carbon before, didn't think that you could ??

Cheers

Steve D
Hello Steve
Here is the solution I choose for my elevators. Considering that for me it is a necessity to remove the elevators for transportation.
Best regards
Stan
Thanks Stan,

That looks like a very good solution.

Remind me - what is the function of the elevator balance tabs and do they help the model in flight ?

Regards

Steve D
Old 06-08-2013, 11:50 AM
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ram3500-RCU
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Default RE: CARF F4U-1 Corsair build thread

Hello Steve. The tabs provided a physical boost to the control, and made it easier for the pilot because it reduced the force needed on the yoke. The ailerons had them as well. The rudder had one of sorts also in the form of the top extended portion.

In our models, they neither help or hinder the control, with the exception of the rudder, which in a wind tunnel test, I'm sure would show a few less ounces needed to deflect over a rudder not so equipped, IMO. They do look cool and are a nice scale addition to the model.

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