GROUP BUILD - Top Flite Giant Scale F4U Corsair
10-18-2013, 12:51 PM
#8877
Senior Member
Join Date: Feb 2011
Location: Comox,
BC, CANADA
Posts: 162
Likes: 0
Received 0 Likes
on
0 Posts
Early last Summer I did my TF GS Corsair maiden and had an elevator flutter at high speed. There was some discussion on it back then and I tried a few things like beefing up the torque wires in the elevator and used stronger servos, but to no avail.
So I decided to find out what I could on flutter and then do a shotgun approach and change everything I thought was needed. As apposed to try one thing at a time.
I found out from a Boeing Engineer that the elevator panel should be balanced 25% from the leading edge.
I found out from guys that raced and won at the RC unlimited air racing that the leading edge of the elevator should be slightly thicker than the trailing edge of the stab.
Good strong, stiff linkage with good mechanical advantage is of course good.
Good powerfull digital servos if you can spend the $$ is of course good.
Hinge gap sealing is not that big an issue I hear, but my gap is tight so that I don't think was ever a problem.
So here is what I did.
I cut off the old elevators, removed the wire torque linkage, the Sullivan 1/4" HD push rods ( snakes as the Brits call them ), removed the old servos.
I built new elevators that were lighter than the old ones and balanced them 25% from the leading edge. I made the leading edge slightly thicker than the trailing edge of the stab. I put the elevator ends and balance tabs permanently fixed with the stab. I did this because I was conserned that my flutter may have started out on the elevator tips where the balancers were? I put two 266 oz/inch digital Savox servos in the tail and each drives one elevator with 440 rod and HD Dubro control horns. This whole set up looks just fine even though not scale, you just don't hardly notice that the tips and balancer are part of the stab. Aircraft balance was not a issue as my CG did not change much, it did go back alittle but within specs.
I flew it last weekend finally , it has been awhile to get a day off with good weather around here.
Zero flutter ! Even in the fastest dive with the G62 screeming! The elevators responded great.
So glad to report problem solved. Sorry I can't tell you which change had the most impact, like I said , I was not going to try one thing at a time due to time constraints.
Going to try to attach a few pics.
So I decided to find out what I could on flutter and then do a shotgun approach and change everything I thought was needed. As apposed to try one thing at a time.
I found out from a Boeing Engineer that the elevator panel should be balanced 25% from the leading edge.
I found out from guys that raced and won at the RC unlimited air racing that the leading edge of the elevator should be slightly thicker than the trailing edge of the stab.
Good strong, stiff linkage with good mechanical advantage is of course good.
Good powerfull digital servos if you can spend the $$ is of course good.
Hinge gap sealing is not that big an issue I hear, but my gap is tight so that I don't think was ever a problem.
So here is what I did.
I cut off the old elevators, removed the wire torque linkage, the Sullivan 1/4" HD push rods ( snakes as the Brits call them ), removed the old servos.
I built new elevators that were lighter than the old ones and balanced them 25% from the leading edge. I made the leading edge slightly thicker than the trailing edge of the stab. I put the elevator ends and balance tabs permanently fixed with the stab. I did this because I was conserned that my flutter may have started out on the elevator tips where the balancers were? I put two 266 oz/inch digital Savox servos in the tail and each drives one elevator with 440 rod and HD Dubro control horns. This whole set up looks just fine even though not scale, you just don't hardly notice that the tips and balancer are part of the stab. Aircraft balance was not a issue as my CG did not change much, it did go back alittle but within specs.
I flew it last weekend finally , it has been awhile to get a day off with good weather around here.
Zero flutter ! Even in the fastest dive with the G62 screeming! The elevators responded great.
So glad to report problem solved. Sorry I can't tell you which change had the most impact, like I said , I was not going to try one thing at a time due to time constraints.
Going to try to attach a few pics.
10-21-2013, 07:04 AM
#8878
My Feedback: (16)
I have been sanding and filling mine. I hope to be ready to paint in a few weeks. Just wanted to let the group know that I ordered the gear doors and the drop tanks for the Hangar 9 ARF (Got it from Advantage hobby in two days) They look good and will save me a bunch of time.
Regards,
Regards,
10-30-2013, 04:31 PM
#8883
Senior Member
Join Date: Oct 2005
Location: QC,
QC, CANADA
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Early last Summer I did my TF GS Corsair maiden and had an elevator flutter at high speed. There was some discussion on it back then and I tried a few things like beefing up the torque wires in the elevator and used stronger servos, but to no avail.
So I decided to find out what I could on flutter and then do a shotgun approach and change everything I thought was needed. As apposed to try one thing at a time.
I found out from a Boeing Engineer that the elevator panel should be balanced 25% from the leading edge.
I found out from guys that raced and won at the RC unlimited air racing that the leading edge of the elevator should be slightly thicker than the trailing edge of the stab.
Good strong, stiff linkage with good mechanical advantage is of course good.
Good powerfull digital servos if you can spend the $$ is of course good.
Hinge gap sealing is not that big an issue I hear, but my gap is tight so that I don't think was ever a problem.
So here is what I did.
I cut off the old elevators, removed the wire torque linkage, the Sullivan 1/4" HD push rods ( snakes as the Brits call them ), removed the old servos.
I built new elevators that were lighter than the old ones and balanced them 25% from the leading edge. I made the leading edge slightly thicker than the trailing edge of the stab. I put the elevator ends and balance tabs permanently fixed with the stab. I did this because I was conserned that my flutter may have started out on the elevator tips where the balancers were? I put two 266 oz/inch digital Savox servos in the tail and each drives one elevator with 440 rod and HD Dubro control horns. This whole set up looks just fine even though not scale, you just don't hardly notice that the tips and balancer are part of the stab. Aircraft balance was not a issue as my CG did not change much, it did go back alittle but within specs.
I flew it last weekend finally , it has been awhile to get a day off with good weather around here.
Zero flutter ! Even in the fastest dive with the G62 screeming! The elevators responded great.
So glad to report problem solved. Sorry I can't tell you which change had the most impact, like I said , I was not going to try one thing at a time due to time constraints.
Going to try to attach a few pics.
So I decided to find out what I could on flutter and then do a shotgun approach and change everything I thought was needed. As apposed to try one thing at a time.
I found out from a Boeing Engineer that the elevator panel should be balanced 25% from the leading edge.
I found out from guys that raced and won at the RC unlimited air racing that the leading edge of the elevator should be slightly thicker than the trailing edge of the stab.
Good strong, stiff linkage with good mechanical advantage is of course good.
Good powerfull digital servos if you can spend the $$ is of course good.
Hinge gap sealing is not that big an issue I hear, but my gap is tight so that I don't think was ever a problem.
So here is what I did.
I cut off the old elevators, removed the wire torque linkage, the Sullivan 1/4" HD push rods ( snakes as the Brits call them ), removed the old servos.
I built new elevators that were lighter than the old ones and balanced them 25% from the leading edge. I made the leading edge slightly thicker than the trailing edge of the stab. I put the elevator ends and balance tabs permanently fixed with the stab. I did this because I was conserned that my flutter may have started out on the elevator tips where the balancers were? I put two 266 oz/inch digital Savox servos in the tail and each drives one elevator with 440 rod and HD Dubro control horns. This whole set up looks just fine even though not scale, you just don't hardly notice that the tips and balancer are part of the stab. Aircraft balance was not a issue as my CG did not change much, it did go back alittle but within specs.
I flew it last weekend finally , it has been awhile to get a day off with good weather around here.
Zero flutter ! Even in the fastest dive with the G62 screeming! The elevators responded great.
So glad to report problem solved. Sorry I can't tell you which change had the most impact, like I said , I was not going to try one thing at a time due to time constraints.
Going to try to attach a few pics.
http://www.rcuniverse.com/forum/rc-w...ml#post6485208
11-01-2013, 08:27 AM
#8886
Senior Member
Join Date: Feb 2011
Location: Comox,
BC, CANADA
Posts: 162
Likes: 0
Received 0 Likes
on
0 Posts
Good idea Duber3, I went the all out route because I wanted to try the balanced elevator trick, and the stock ones were very heavy, so had to go. I also never used the metal long push rods and went with Sullivan 1/4 nylon rods, and I wanted to change them out too.
But if I was ever to build another one , I may do what you did , but maybe put the servo or servos 1/2 down the tail and make a hatch? Just to keep the linkage shorter.
Tom
But if I was ever to build another one , I may do what you did , but maybe put the servo or servos 1/2 down the tail and make a hatch? Just to keep the linkage shorter.
Tom
11-01-2013, 04:43 PM
#8887
Senior Member
Join Date: Oct 2005
Location: QC,
QC, CANADA
Posts: 179
Likes: 0
Received 0 Likes
on
0 Posts
Good idea Duber3, I went the all out route because I wanted to try the balanced elevator trick, and the stock ones were very heavy, so had to go. I also never used the metal long push rods and went with Sullivan 1/4 nylon rods, and I wanted to change them out too.
But if I was ever to build another one , I may do what you did , but maybe put the servo or servos 1/2 down the tail and make a hatch? Just to keep the linkage shorter.
Tom
But if I was ever to build another one , I may do what you did , but maybe put the servo or servos 1/2 down the tail and make a hatch? Just to keep the linkage shorter.
Tom
.I did the same trick on my TF GS P51
I really love my corsair, I hope you enjoy it as much as I do
Eric
11-01-2013, 07:07 PM
#8888
I've used it a couple of times. There are a few things you should know. First, it will not conform to compound curves, only curves in one direction. This means that on the F4U, you cannot use it for sections such as the gull wing center section, or for much of the fuselage. You could use it for most of the outer wing pane (except for perhaps the underside wingtips) and you could use it for the stabilizers, rudder, elevators and outer wing flaps. I have a horizontal stab for an F4U that is covered with it. Well, except I use a generic version which is less expensive than FliteSkin from ACP Composites. Also, if you work in smaller pieces, you can work around some of the larger compound curves. I've seen one person use it in 3 or 4 sections to work around the compound curve of an 80" Spitfire wing. When you are ready to glue it down, be sure to sand the bonding surface with 80 to 100 grit to give some tooth for the gorilla glue to grab.
Scott
11-03-2013, 07:15 PM
#8889
My Feedback: (3)
Join Date: Jul 2002
Location: Willimantic, CT
Posts: 1,180
Likes: 0
Received 0 Likes
on
0 Posts
Ok sometimes you can't see the forest from the trees, If you have a retractable tai wheel with the control arm for turning the wheel on a pull pull setup to a servo does this get hooked up to the rudder as a slave or do they independently plug into different channels in the receiver
George
CORSAIR Brotherhood # 1
George
CORSAIR Brotherhood # 1
11-03-2013, 07:31 PM
#8890
Ok sometimes you can't see the forest from the trees, If you have a retractable tai wheel with the control arm for turning the wheel on a pull pull setup to a servo does this get hooked up to the rudder as a slave or do they independently plug into different channels in the receiver
George
CORSAIR Brotherhood # 1
George
CORSAIR Brotherhood # 1
I've seen it done both ways.
If you tie it to a Y cable to the rudder servo then you need to mechanically adjust the tail wheel servo travel to make it right.
If you use an independant channel slaved to the Rudder you may have a method to program the travel on that channel from the transmitter.
Scott
11-05-2013, 12:25 PM
#8892
I've really got to get this plane finished. We had a baby 7 weeks ago today, so between wanting to stay home with her and colder weather coming, maybe I can get some work done. Pretty sure I left off having laid up glass for my gear doors, but got snagged in trying to figure out how I was going to hinge and actuate them and that's where it sits.
Other decisions to make:
1. How to mount/actuate the DaddySam tailwheel - if anyone has pictures of their installation/linkage, that would be much appreciated.
2. Flap actuation. I think I have plenty of data on this, just need to finish building the flaps and get to work. As of now I think I'm going to use the original setup, can't remember if that was what most did or if others used an external linkage.
3. Elevator linkage, I plan on doing what duber referenced above. The servos will stay up in the original location, but run the rods outside to control horns instead of using those torque rods.
I also still need to pick up a powerplant. I'm probably still going to go with a G-62, but am opening my eyes for other options as well.
Other decisions to make:
1. How to mount/actuate the DaddySam tailwheel - if anyone has pictures of their installation/linkage, that would be much appreciated.
2. Flap actuation. I think I have plenty of data on this, just need to finish building the flaps and get to work. As of now I think I'm going to use the original setup, can't remember if that was what most did or if others used an external linkage.
3. Elevator linkage, I plan on doing what duber referenced above. The servos will stay up in the original location, but run the rods outside to control horns instead of using those torque rods.
I also still need to pick up a powerplant. I'm probably still going to go with a G-62, but am opening my eyes for other options as well.
But man, it does look sweet.
11-06-2013, 11:23 AM
#8895
Join Date: Jun 2012
Location: Bristol, CT
Posts: 4,002
Likes: 0
Received 0 Likes
on
0 Posts
Hey guys. Just thought I'd share my happiness with ya. Until now, all I was able to afford was a 60 size corsair by top flite with a 20 cc, and believe me, I was more than happy with that. I always kept up on this thread, mainly because I love to build, I love the F4U, and it was a dream to me to someday own the GS Corsair. Well today I finally bought one. Unfortunately it's already been started. In fact, a lot of the framing has been done, but most of the sheeting still needs to be installed so I can at least inspect the framing and make changes if necsasary. I picked it up for a buck and a half. I feel like that was a good deal. Even if it takes me a year or two to get it airworthy, I'm ok with that. I'm now a happy, happy boy.im sure I'll have a lot of questions, and I'll post pics of it when I pick it up. Maybe you guys might be able to spot something that's not right. Thanks, Steve.
11-07-2013, 09:51 AM
#8898
Join Date: Jun 2012
Location: Bristol, CT
Posts: 4,002
Likes: 0
Received 0 Likes
on
0 Posts
Ok, so I picked up the corsair, and I'd say I got a few goodies. Not so much for the corsair ( which I think looks to be in pretty good shape.), but this is what I got. The GS Corsair, a 60 size top flite corsair fuse, already framed up with a bunch of other parts, a framed and sheeted great planes super skybolt with everything needed to finish. Just has a bit of hanger rash but nothing major. As well as a partial Pica 1/5 Waco kit. The plans, manual, and all abs parts are there and in good shape. I think for $190 , I made out ok. I know one thing, my winter season just got pretty much planed out for me. What do you guys think? I'll post pics of the corsair soon. Steve.
11-07-2013, 09:54 AM
#8899
It looks like you're going to be busy Steve!
Nice purchase!
Scott
Nice purchase!
Scott
Originally Posted by [email protected]
Ok, so I picked up the corsair, and I'd say I got a few goodies. Not so much for the corsair ( which I think looks to be in pretty good shape.), but this is what I got. The GS Corsair, a 60 size top flite corsair fuse, already framed up with a bunch of other parts, a framed and sheeted great planes super skybolt with everything needed to finish. Just has a bit of hanger rash but nothing major. As well as a partial Pica 1/5 Waco kit. The plans, manual, and all abs parts are there and in good shape. I think for $190 , I made out ok. I know one thing, my winter season just got pretty much planed out for me. What do you guys think? I'll post pics of the corsair soon. Steve.
11-07-2013, 11:35 AM
#8900
Hi Steve,
I see you are in Bristol CT. You should take a day trip down to the Connecticut Air and Space Center in Stratford CT. They are restoring a Goodyear built FG1-D Corsair (Same as the F4U1-A). They are located in the original Chance Vought factory test center. I had the honor of spending a few days working on it when it was at Ezell Aviation in Breckenridge TX a couple of summers ago.
http://cascstratford.wordpress.com/e...dyear-corsair/
www.ezellaviation.com
Scott
I see you are in Bristol CT. You should take a day trip down to the Connecticut Air and Space Center in Stratford CT. They are restoring a Goodyear built FG1-D Corsair (Same as the F4U1-A). They are located in the original Chance Vought factory test center. I had the honor of spending a few days working on it when it was at Ezell Aviation in Breckenridge TX a couple of summers ago.
http://cascstratford.wordpress.com/e...dyear-corsair/
www.ezellaviation.com
Scott