Van's Air Force
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RV-7 aileron bellcranks in RV-6 wings
- Thread starter vtfast
- Start date
jsharkey
Well Known Member
pierre smith
Well Known Member
Hi Tom.......
....We're up here in Louisville and are putting in our Tru Trak servos in our -6A tomorrow afternoon. We also have a -7 with the servos in but the wings are open if you'd like to drive up here around 2:00 p.m. or later, we'll be here 'til dark then you can look at both.
Regards
....We're up here in Louisville and are putting in our Tru Trak servos in our -6A tomorrow afternoon. We also have a -7 with the servos in but the wings are open if you'd like to drive up here around 2:00 p.m. or later, we'll be here 'til dark then you can look at both.
Regards
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Hi jsharkey,
The set up does not give a straight line out to the ailerons from the bell crank and after speaking with????? (Sorry I cannot remember his name) about the -6 setup he was talking about putting the -7 setup in his -6. He told me that it has been done by others. After looking at my friends -7 the installation is much nicer/cleaner. It will eliminate having to bend control rods and other unspoken mods. to keep the ailerons from binding and cutting big uneven holes in the aft spar.
Thanks for the reply.
Hi Pierre,
I would like to come up and see what you have only one problem, I work weekends. Is there a time available during the week you work on the projects for me to drop in and see what your working on?
Thanks for the reply
Tom
Kyle Boatright
Well Known Member
Bending control rods? Not on my -6. I've never even heard of bending a control rod in an RV. Besides, bending a control rod is a bad thing from a structural perspective.
Let me rephrase that statement:
It will eliminate the possibility of having to bend control rods and other unspoken mods.
Bending things to make them work is not my idea of a structural sound solution to a problem.
All I am asking is if anybody has done this or knows somebody that has whom I can speak with about this!
It will eliminate the possibility of having to bend control rods and other unspoken mods.
Bending things to make them work is not my idea of a structural sound solution to a problem.
All I am asking is if anybody has done this or knows somebody that has whom I can speak with about this!
L.Adamson
Well Known Member
I've never had to bend control rods in my 6A, nor would I. There are no "unspoken mods" in the control system either.
L.Adamson ---- RV6A
Kyle Boatright
Well Known Member
I think you did receive help, which was the message that there is no need to bend control rods or make "unspoken mod's" to the stock control system, so you're contemplating fixing a problem that doesn't exist.
As to whether your modification will work, who knows. As someone who has frequented this forum and the Matronics list for well over a decade (yikes!), I have never heard of the modification you're contemplating.
Kyle,
Thanks, This is what I was looking for.
I don't want to make the mistakes I have seen on other wings due to unknown issues by their builders. I have seen what I have suggested and beleive the builders may not have realized that this was not the normal course to be taken during the construction of the -6 wing. The idea suggested to use the -7 setup was made by a fellow RV builder and to me made sound sense. The angle of the control rods coming off the bellcrank to the aileron seem excessive on the -6 compared to the straight line output of the -7 setup. This is why I am asking these questions.
I currently have one rib modified and the other is in work for the aileron bellcranks and before I cut this rib I want to explore all avenues and ideas to see if there are other options to consider.
Thanks for the input.
Tom
Thanks, This is what I was looking for.
I don't want to make the mistakes I have seen on other wings due to unknown issues by their builders. I have seen what I have suggested and beleive the builders may not have realized that this was not the normal course to be taken during the construction of the -6 wing. The idea suggested to use the -7 setup was made by a fellow RV builder and to me made sound sense. The angle of the control rods coming off the bellcrank to the aileron seem excessive on the -6 compared to the straight line output of the -7 setup. This is why I am asking these questions.
I currently have one rib modified and the other is in work for the aileron bellcranks and before I cut this rib I want to explore all avenues and ideas to see if there are other options to consider.
Thanks for the input.
Tom
Tom Hunter
Member
Making changes to control systems
I would suggest you confer with Van before making a control systems change. The reason that the -7 aileron bell crank is different than the -6 is not casual. Making such a switch if the lengths of the bell crank are not identical and would impact the flying characteristics of the airplane.
Unfortunately, if you read the NTSB accident reports you will find that there are a disturbing number of accidents caused by builders NOT FOLLOWING the blue prints and making changes that down the road come back to bite them, or the person who is in the plane at the time.
You should also be aware that if you do make an "Undocumented" change to your aircraft that can impact the safe operation of your plane, and "IF" your plane is later involved in an accident, and "if" the insurance company learns of your deviation from the design's specs, you can find yourself in an awkward situation.
Tom
I would suggest you confer with Van before making a control systems change. The reason that the -7 aileron bell crank is different than the -6 is not casual. Making such a switch if the lengths of the bell crank are not identical and would impact the flying characteristics of the airplane.
Unfortunately, if you read the NTSB accident reports you will find that there are a disturbing number of accidents caused by builders NOT FOLLOWING the blue prints and making changes that down the road come back to bite them, or the person who is in the plane at the time.
You should also be aware that if you do make an "Undocumented" change to your aircraft that can impact the safe operation of your plane, and "IF" your plane is later involved in an accident, and "if" the insurance company learns of your deviation from the design's specs, you can find yourself in an awkward situation.
Tom
I think it is primarily because the aileron on a 7 or 8 is longer than it is on a 6.
The stick travel VS deflection angle is about the same on all of them, though it is done with a different mechanism.
Kyle Boatright
Well Known Member
You can probably save yourself a phone call.
Scott McDaniels (RVBuilder 2002) is a long time employee of Van's. He works in the prototype shop and is extremely familiar with every model Van's offers.
Take heed of his post in this thread...
Kevin Horton
Well Known Member
The relationship between control stick displacement and aileron deflection depends on the interrelationship between the control stick design, aileron bellcrank, aileron control horn, pushrod lengths, etc. I think the aileron hinges and control horns are equivalent on the RV-6 and -7. But I'm not sure about the control stick geometry - specifically the angles and distances between the lateral control pivot and where the aileron pushrods attach.
How does the RV-7 control stick assembly compare to that of the RV-6? If the stick designs differ, this may explain why the bellcranks need to have different geometry to achieve the same relationship between stick angle and aileron angle.
How does the RV-7 control stick assembly compare to that of the RV-6? If the stick designs differ, this may explain why the bellcranks need to have different geometry to achieve the same relationship between stick angle and aileron angle.
The RV-6 and 7 use the same control stick and control column. The hinge brackets for the ailerons are also the same so all of the mechanical relationship is the same, just connected in a slightly different manner.
I believe the main reason for the change was to make the wing easier to build and reduce parts count (spar comes ready for mounting the brackets, No ribs to modify, etc.). The old bellcrank design may actually have an advantage in regards to maint. since it uses (I think) sealed bearings at the rotation point instead of a bronze style bushing that will wear over time.
I don't see any benefit to an RV-6 builder making this modification. Since the orig. purpose was to reduce construction time, he would just be trading the work to modify two wing ribs, for the work to modify most of the control system (all four push rod lengths custom made, bellcrank attachment to the spar web, etc.
Note that with the new style bellcrank installation on an RV-7/8 wing the tie down anchor was used as a spar web stiffener. It bridges between teh spar cap matterial on teh top and bottom of teh spar. This would also need to be incorporated if modifying the wing on a 6, which futher complicates the work involved.
Their is no real benefit to making this change (I do not believe it will change the control /handling qualities in any way) unless you are trying to drag out your wing construction as long as possible.
The weight is probably about a wash. It will cost more because you have to buy more parts.
My two cents...
I believe the main reason for the change was to make the wing easier to build and reduce parts count (spar comes ready for mounting the brackets, No ribs to modify, etc.). The old bellcrank design may actually have an advantage in regards to maint. since it uses (I think) sealed bearings at the rotation point instead of a bronze style bushing that will wear over time.
I don't see any benefit to an RV-6 builder making this modification. Since the orig. purpose was to reduce construction time, he would just be trading the work to modify two wing ribs, for the work to modify most of the control system (all four push rod lengths custom made, bellcrank attachment to the spar web, etc.
Note that with the new style bellcrank installation on an RV-7/8 wing the tie down anchor was used as a spar web stiffener. It bridges between teh spar cap matterial on teh top and bottom of teh spar. This would also need to be incorporated if modifying the wing on a 6, which futher complicates the work involved.
Their is no real benefit to making this change (I do not believe it will change the control /handling qualities in any way) unless you are trying to drag out your wing construction as long as possible.
The weight is probably about a wash. It will cost more because you have to buy more parts.My two cents...
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Thanks Scott.
Either way will work then. The question is like you say, do I want to really drag this out any further than neccesary. I was drilling skins and ribs today and did a whole lot of looking at the system and beleive it would be pretty straight forward but the extra cost probably makes it a bust at this point.
Thank you for your input and I hope to here more from you with other questions I may have in the future.
Tom
Either way will work then. The question is like you say, do I want to really drag this out any further than neccesary. I was drilling skins and ribs today and did a whole lot of looking at the system and beleive it would be pretty straight forward but the extra cost probably makes it a bust at this point.
Thank you for your input and I hope to here more from you with other questions I may have in the future.
Tom
I think it was me you talked too
I believe I was speaking with you on the phone about switching over to a RV-7 style aileron bellcrank. It could be more work than it's worth but I'm still thinking I might do it. The main reason is so I do not have to carve such a big hole in the rear spar. I see the difference in -7 vs -6 holes and they are considerable. I also like the style of the -7 and I think they are easier to work on and you don't have to worry about getting the little washers in there just perfect as you do on the -6. I might have been doing this wrong, but laying on my back during final assembly and trying to reach up in this small hole with both hands to insert the small spacer washers in the bellcrank rod ends was not fun. I know the spars are different but its not that big of a mod to do and I think it's stronger in the long run. Cutting up ribs and making up bellcranks will take just as much time. Also, you could eliminate the stub rib from the wing as you do on the -4, -7, -8's. The angle on the -6 was so extreme that Van's added that rib in there for reinforcment beciause of the bigger hole you had to make to allow clearance for the pushrod through the spar. There have been several incidences where people have put .063 angles on the bellcrank ribs instead of 1/8" and they have also turned around the bellcrank backwards as well. The bellcrank does have one longer side to it and it you don't get it in there right the throw will cam over and have a tendency to lockup. My RV-6 flew great and the stick forces were low-almost to low. I had to fly that thing around everywhere I went. My Dad said it was almost as touchy as his RV-3's. It was fun but it wore you out on long trips. I would prefer it to be a little more sluggish (not much) but just enough to give you a break it you want to let go for a bit to grab something.
This is what is great about RV-s, you can do anything you want-just as long as it is safe. I don't see the RV-7 style setup being any unsafer than the -6 and in fact it's less confusing with less parts. Once you get the learning curve figured out on the first wing the second is a snap. I personally will be changing mine to a RV-7 style, but that's just me.
Good Luck
Aden Rich
I believe I was speaking with you on the phone about switching over to a RV-7 style aileron bellcrank. It could be more work than it's worth but I'm still thinking I might do it. The main reason is so I do not have to carve such a big hole in the rear spar. I see the difference in -7 vs -6 holes and they are considerable. I also like the style of the -7 and I think they are easier to work on and you don't have to worry about getting the little washers in there just perfect as you do on the -6. I might have been doing this wrong, but laying on my back during final assembly and trying to reach up in this small hole with both hands to insert the small spacer washers in the bellcrank rod ends was not fun. I know the spars are different but its not that big of a mod to do and I think it's stronger in the long run. Cutting up ribs and making up bellcranks will take just as much time. Also, you could eliminate the stub rib from the wing as you do on the -4, -7, -8's. The angle on the -6 was so extreme that Van's added that rib in there for reinforcment beciause of the bigger hole you had to make to allow clearance for the pushrod through the spar. There have been several incidences where people have put .063 angles on the bellcrank ribs instead of 1/8" and they have also turned around the bellcrank backwards as well. The bellcrank does have one longer side to it and it you don't get it in there right the throw will cam over and have a tendency to lockup. My RV-6 flew great and the stick forces were low-almost to low. I had to fly that thing around everywhere I went. My Dad said it was almost as touchy as his RV-3's. It was fun but it wore you out on long trips. I would prefer it to be a little more sluggish (not much) but just enough to give you a break it you want to let go for a bit to grab something.
This is what is great about RV-s, you can do anything you want-just as long as it is safe. I don't see the RV-7 style setup being any unsafer than the -6 and in fact it's less confusing with less parts. Once you get the learning curve figured out on the first wing the second is a snap. I personally will be changing mine to a RV-7 style, but that's just me.
Good Luck
Aden Rich
Hi Aden,
Yes we did speak to each other about this, I just didn't want to say names on the forum. I appreciate your input and I have purchased all of the material to make the switch already and I am in the process of installing them. I lalso like the setup better as well, guess we will find out if it works right or not. One rib is alreay setup with the bellcrank so I have not decided if I am going to replace the rib or just remove the brackets and put some peices back on the rib, I have time to decide still. Replacing the rib would be real quick to do so I probably will just do that. I will take pictures of the installed bellcranks along with what was required to do it if you are interested, it really is straight forward with very little change to the spar itself.
I see you purchased a fuselage, I will be ordering mine this month if all goes well and we all still have a job.
Yes we did speak to each other about this, I just didn't want to say names on the forum. I appreciate your input and I have purchased all of the material to make the switch already and I am in the process of installing them. I lalso like the setup better as well, guess we will find out if it works right or not. One rib is alreay setup with the bellcrank so I have not decided if I am going to replace the rib or just remove the brackets and put some peices back on the rib, I have time to decide still. Replacing the rib would be real quick to do so I probably will just do that. I will take pictures of the installed bellcranks along with what was required to do it if you are interested, it really is straight forward with very little change to the spar itself.
I see you purchased a fuselage, I will be ordering mine this month if all goes well and we all still have a job.
