bent or offset taller stick - panel interference

[skirting_virga]

I'm trying to improve the ergonomics of the 8 stick, and have searched several threads. It seems like there are many versions of a very modest offset, achieved through either bends or welding. My perception is that this is insufficient for the improvements I'm looking for.

I was able to find other builders who tried a more radical solution to offset the stick rearward enough that panel clearance was not a concern, allowing an increase in height. I think this is a perfect solution ergonomically, but after many attempts to mock up such an offset, I can't get it to clear the panel. The fore-aft travel is simply too much to both land in a reasonable position at full aft, and avoid the panel at full forward. I have a thin build, so there is no stomach in the way - it just can't be done on my airplane for some reason.

These posts were the inspiration for trying combinations of height, offset, and angle:

RV8 Bent Stick

OK, I’m trying the google photo sharing instruction on this site to see if I can get it to work. I have the app on my iPad because my son in law, who is an excellent photographer, uses google to post pics of my grandchildren in a shared album. The instructions say something about right clicking...

vansairforce.net

RV8 Bent Stick

OK, I’m trying the google photo sharing instruction on this site to see if I can get it to work. I have the app on my iPad because my son in law, who is an excellent photographer, uses google to post pics of my grandchildren in a shared album. The instructions say something about right clicking...

vansairforce.net

Yesterday, I used some hardware store brackets to mock up the stick, trying every permutation of height, offset, and angle I thought might work. All of them either run into my body at full aft, or run into the panel at full forward. I'm starting to wonder if it's an issue of rigging, and my elevator has more travel than it strictly needs. It's frustrating enough that I would consider adjusting the bottom of the lever distance (probably spoiling the "control harmony" in the process) to see if I can eliminate an inch or so of travel at the top of the stick.

Does anyone have advice for how to achieve a taller, more aft stick? The panel interference requiring a short stick is a straightjacket so far. Is my seat cushion too tall? Is the range of elevator travel excessive?

The picture shows the Vans stick weldment cut to the maximum height allowable to clear the panel - it is very short, even with a simple wood grip. The offset and height shown with my bracket mockup is about what I would want - probably an inch shorter with a little more forward angle of the grip:

 

[Saville]

One possibility is to cant the grip forward so that, even though the stick is too short you can get more of the grip in your hand.

 

[Tall_Order]

I think the panel is likely structural, however could a recontoured shorter replacement panel of similar strength reduce or eliminate the need for stick mods? A lot of variables (avionics choices, pilot stature, recline if there is a tall pilot mod, seat cushion thickness, stick grip choice, etc) so some choices work better for some than others…. Good luck

 

[Webb]

Article in Kitplanes on how to make an offset stick.

Front Control Stick

Most of us figure out pretty quickly that the front control stick needs to be cut to fit in the RV-8. If left at its original length, it bangs into the instrument panel before you can get full forward on the controls. The two big changes most of us make are bending the stick, and adding some...

www.kit-plane-advice.com

 

[skirting_virga]

One possibility is to cant the grip forward so that, even though the stick is too short you can get more of the grip in your hand.

I've explored a few versions of small offset/angle changes and come to the conclusion that a lot of the strain on my shoulder is simply due to stick height. I have no wiggle room to make the stick taller presently without offsetting it back several inches. I thought low pass had discovered a formula that works, but copying his numbers doesn't clear the panel. I would have to move the stick back an additional 1-2", which is excessive and doesn't clear my body.

I think the panel is likely structural, however could a recontoured shorter replacement panel of similar strength reduce or eliminate the need for stick mods? A lot of variables (avionics choices, pilot stature, recline if there is a tall pilot mod, seat cushion thickness, stick grip choice, etc) so some choices work better for some than others…. Good luck

I'm not opposed to a panel relief, but as the plane is presently flying, reinventing the panel would be a lot of work. I would consider if I do a panel upgrade down the road in a few years, but a cutout would really limit usable panel real estate in that scenario. This plane does not have the tall pilot mod. I do note that this stick grip is a bit on the tall side (the stick fits 2.5" into it, but it is 6.3" tall.

The only way seat cushion thickness comes into play in this (IMO) is that I could do another 1" more offset if the back were thinner, but those dimensions are much more than Bryan (low pass) needed to achieve this as far as I can tell. He was using a ~5.5" aft offset at ~10.5" up the stick from the pivot, with a slight angle. I tried this and several permutations of height/angle/offset, with no luck. 5.5" or less hits the panel at 90 degrees or any slight forward angle. ~6.0" is too close to my body or the buckle while still not clearing the panel. ~6.5" and no forward angle is close to clearing the panel, but hits my body. Any slight forward angle and it doesn't clear the panel anymore.

Article in Kitplanes on how to make an offset stick.

Front Control Stick

Most of us figure out pretty quickly that the front control stick needs to be cut to fit in the RV-8. If left at its original length, it bangs into the instrument panel before you can get full forward on the controls. The two big changes most of us make are bending the stick, and adding some...

www.kit-plane-advice.com

I saw this! One of the guides I was able to find scouring the forums about the issue. As far as I can tell, this stick must be stock height (i.e. too short) to clear the panel, and the jog backwards is very modest. I think a modest offset like this might be a slight improvement, but was really hoping for more and concluded the stick needed to be taller to do so. Bryan (low pass) figured it out for his plane and published pictures and dimensions (see links above) but those same numbers don't seem to work on my plane.

I'm almost at the point where I'm asking if it's safe and feasible to slightly limit total elevator travel to prevent the stick from interfering with the panel. My concerns are obvious: don't do anything that would cause pitch limits to compromise safety. I don't fly aerobatics and the plane doesn't have inverted fuel/oil, so there's no concern about needing a lot of forward elevator for inverted flight. Is spin recovery going to be compromised by limiting forward elevator? Is it even physically possible to set elevator travel at the bellcrank? Somewhere else? Is it possible to limit travel while being within Vans spec?

It seems crazy to be asking about limiting elevator travel, but this is frustrating - I really want better stick ergonomics, and it seems at least one other builder has achieved it, but he hasn't logged in in 6 months, and his dimensions don't seem to work for my plane. I think Vans could have done a much better job on the 8 in this respect, but the design is ~30 years old and has not been meaningfully updated. If they were designing an 8 in 2024, there's no way this stick design would be in the plane.

 

[Scott Hersha]

I did the cut and weld offset on both of my RV8’s, and it worked well (see first pic). The offset was 2” aft from centerline of the upper grip area to centerline of the lower part.
I did a slightly more elegant mod to my RV4 front stick. The RV4 stick and the RV8 stick are the same. I cut the stick where I wanted it and inserted the RV14 stick inside (it’s smaller diameter). It didn’t fit tightly, so I machined down a piece of 4130 tube to use as a shim to make it fit tight. Drilled for two bolts through the assembly (Second two pics). I had moved my front seat aft almost three inches for comfort, and it all turned out great.

 

[Ironflight]

Have you measured your elevator travel and checked what you have against the specs in the drawings (sorry - don’t have the handy to tell you what they should be….)? I would absolutely NOT change the rigging if you have the design level of travel - its there for te aircraft’s flight envelope, and while you might not use it for aerobatics, the next owner might, and the fact that the travel has been limited might not get communicated.

The other thing to check is where the “neutral” point is set for the stick and the elevator - its possible yours is not centered in the range properly.

I have flown a wide variety of -8’s with different stick lengths and bends. I personally like them shorter with my forearm on my thigh. I find “tall” to be too sensitive…but others like tall. But everyone has different body proportions, so who’s to say what’s “right” for you? There are a couple thousand of these flying just fine for most people, so I don’t think condemning the design outright is appropriate.

Start by checking all the rigging.

 

[Mikeyb]

I was impressed by the change in perceived stick force with a 1” change in the seat height

 

[Saville]

One possibility is to cant the grip forward so that, even though the stick is too short you can get more of the grip in your hand.

Skirting_Virga replied:
I've explored a few versions of small offset/angle changes and come to the conclusion that a lot of the strain on my shoulder is simply due to stick height. I have no wiggle room to make the stick taller presently without offsetting it back several inches. I thought low pass had discovered a formula that works, but copying his numbers doesn't clear the panel. I would have to move the stick back an additional 1-2", which is excessive and doesn't clear my body.

I wasn't suggesting that canting the grip forward must be the ONLY change. But I am pretty sure it helps a lot. Just put your hand next to the present stick but cant it forward a little bit and see for yourself.

Also, if you rotate the grip so that the :trigger" is pointing a little left, that plus angling the grip increases the improvement. Might not totally solve the issue but every little bit helps.

My point is that I don't think there is ONE solution for this. I think to solve the problem a number of things have to change. I have the same issue as you do: The straight stick is too low and my index finger is never on the stick and the next finger is only partly on the stick. I have a thick seat cushion but I have to say that I like sitting up high. Still, that may have to be part of the overall solution.

 

[skirting_virga]

I did the cut and weld offset on both of my RV8’s, and it worked well (see first pic). The offset was 2” aft from centerline of the upper grip area to centerline of the lower part.
I did a slightly more elegant mod to my RV4 front stick. The RV4 stick and the RV8 stick are the same. I cut the stick where I wanted it and inserted the RV14 stick inside (it’s smaller diameter). It didn’t fit tightly, so I machined down a piece of 4130 tube to use as a shim to make it fit tight. Drilled for two bolts through the assembly (Second two pics). I had moved my front seat aft almost three inches for comfort, and it all turned out great.

Your modification is actually where I started! Thought I could get the RV-14 stick adapted. It turns out, it's impossible in my plane with this grip, which inserts over 2.5" of tube, then sticks up about 3.75" additional above the tube. By the time you're done, the grip always ends up above the bottom of the panel. To put the -14 stick any lower causes it to interfere with the seat - this is why I decided on a cut-and-weld offset, to drop the top of the stick lower than would be possible with S-bends.

Have you measured your elevator travel and checked what you have against the specs in the drawings (sorry - don’t have the handy to tell you what they should be….)? I would absolutely NOT change the rigging if you have the design level of travel - its there for te aircraft’s flight envelope, and while you might not use it for aerobatics, the next owner might, and the fact that the travel has been limited might not get communicated.

I'm definitely proceeding cautiously. I know enough to realize that it needs to be within design specs or I could be treading in dangerous territory without realizing it.

The other thing to check is where the “neutral” point is set for the stick and the elevator - its possible yours is not centered in the range properly.

I have flown a wide variety of -8’s with different stick lengths and bends. I personally like them shorter with my forearm on my thigh. I find “tall” to be too sensitive…but others like tall. But everyone has different body proportions, so who’s to say what’s “right” for you? There are a couple thousand of these flying just fine for most people, so I don’t think condemning the design outright is appropriate.

Start by checking all the rigging.

I honestly haven't figured out how to check the rigging yet. I did verify that the most aft position of the stick travel is about as close as it can get without contacting the sheet metal underlying the seat, or the seat cushion at full aft extents. I did modify the position of the rod end on the pitch pushrod slightly (screwed out) to achieve this. It's still ~5" in front of the panel at full forward stick which seems like a very odd ergonomic choice and that's why I'm a bit crabby about it. I can't say what "optimal" really is, but my perception is that the best ergonomics for my dimensions and flying (predominantly XC) may conflict with what others would need.

I can't fairly say that Vans was wrong to build it this way, but it feels clearly suboptimal to me. Likewise, the factory position of the throttle quadrant is much further forward and to the left vs where I would choose to mount it (and I found an example of a plane where someone moved it substantially aft and right for better fit). This particular plane should be built with very few, if any, deviations from the plans, so it's as-Vans-intended. I'm average height, so this may be a case of "one size fits most" design that compromises comfort with the intention of fitting a wider range of possible pilots.

I wasn't suggesting that canting the grip forward must be the ONLY change. But I am pretty sure it helps a lot. Just put your hand next to the present stick but cant it forward a little bit and see for yourself.

Also, if you rotate the grip so that the :trigger" is pointing a little left, that plus angling the grip increases the improvement. Might not totally solve the issue but every little bit helps.

My point is that I don't think there is ONE solution for this. I think to solve the problem a number of things have to change. I have the same issue as you do: The straight stick is too low and my index finger is never on the stick and the next finger is only partly on the stick. I have a thick seat cushion but I have to say that I like sitting up high. Still, that may have to be part of the overall solution.

I've done the grip rotation and agree that a small offset + a tilt forward would be some improvement, but this project is going to take enough effort that I would like to optimize it more. To me, that's getting the grip 2+" higher and ~5" further aft, which seems impossible from where I stand.

 

[RV8JD]

I honestly haven't figured out how to check the rigging yet. I did verify that the most aft position of the stick travel is about as close as it can get without contacting the sheet metal underlying the seat, or the seat cushion at full aft extents. I did modify the position of the rod end on the pitch pushrod slightly (screwed out) to achieve this. It's still ~5" in front of the panel at full forward stick which seems like a very odd ergonomic choice and that's why

If you haven’t already, check the elevator stops and elevator travel first to make sure they are properly adjusted. From the Construction Manual, Page 8-59:

• Allowable elevator travel is found in Section 15. Trim material from the F-811D-1 Spacer / Control Stop and F- 812B-1 Angle / Control Stop to allow for the proper amount of elevator travel (See “Elevator Stop Adjustment”, DWG 78). Trim the stops so the flanges of both WD-605-1-L/R Elevator Horns contact the stops at maximum deflection. Relieve the bottom flange of the HS-603 Rear Spar if this was not done during the horizontal stabi- lizer construction, but DO NOT remove any material from the HS-609PP Rear Spar Reinf. Bar (See “Exploded Iso View”, DWG 3).

Also, the bottom of Page 8-58 has the rigging info.

This will not solve your “issue”, but check these items before adjusting rod ends and such.

 

[jbDC9]

Your modification is actually where I started! Thought I could get the RV-14 stick adapted. It turns out, it's impossible in my plane with this grip, which inserts over 2.5" of tube, then sticks up about 3.75" additional above the tube. By the time you're done, the grip always ends up above the bottom of the panel. To put the -14 stick any lower causes it to interfere with the seat - this is why I decided on a cut-and-weld offset, to drop the top of the stick lower than would be possible with S-bends.

Same here! I tried Scott's idea of a -14 stick adapted to my -8 stick base. While it's a great idea, it just didn't work in my plane; the stick ended up bumping into the lower seat cushion and limited my up elevator travel. No bueno. So, I ended up shamelessly copying Low Pass Bryan's idea, but had to make a few tweaks to make it work. I used some heavy cardboard to make several templates, experimenting with aft offsets and angles... after a few tries I found what works. I have a simple stick grip with no switches/buttons on top; it clears the panel by 1/8" and clears the lower seat pan and cushion. Score! I bought a new RV-8 stick base along with some 4130 steel tube stock and had a local welder fabricate it. I'm happy with it and will keep it... what I didn't keep was the dimensions I used. Oops.

 

[skirting_virga]

If you haven’t already, check the elevator stops and elevator travel first to make sure they are properly adjusted. From the Construction Manual, Page 8-59:

• Allowable elevator travel is found in Section 15. Trim material from the F-811D-1 Spacer / Control Stop and F- 812B-1 Angle / Control Stop to allow for the proper amount of elevator travel (See “Elevator Stop Adjustment”, DWG 78). Trim the stops so the flanges of both WD-605-1-L/R Elevator Horns contact the stops at maximum deflection. Relieve the bottom flange of the HS-603 Rear Spar if this was not done during the horizontal stabi- lizer construction, but DO NOT remove any material from the HS-609PP Rear Spar Reinf. Bar (See “Exploded Iso View”, DWG 3).

Also, the bottom of Page 8-58 has the rigging info.

This will not solve your “issue”, but check these items before adjusting rod ends and such.

thanks for identifying the correct manual sections so I can start to figure it out. There is a tolerance - and a particularly wide one - on the elevator travel. Unfortunately, it seems that the stops are physically riveted in place and potentially trimmed to fit.

Up elevator Min 25°, Max 30°
Down elevator Min 20°, Max 25°

I'm guessing this plane is probably set up closer to the max than the min, which would have a significant effect on stick travel. If it is, it seems like there is not an "approved" way to limit travel per the plans. Intuitively I would want to do that with a nylon spacer on top of the stop, but I'd prefer not to be the first one ever to try it.

 

[skirting_virga]

Same here! I tried Scott's idea of a -14 stick adapted to my -8 stick base. While it's a great idea, it just didn't work in my plane; the stick ended up bumping into the lower seat cushion and limited my up elevator travel. No bueno. So, I ended up shamelessly copying Low Pass Bryan's idea, but had to make a few tweaks to make it work. I used some heavy cardboard to make several templates, experimenting with aft offsets and angles... after a few tries I found what works. I have a simple stick grip with no switches/buttons on top; it clears the panel by 1/8" and clears the lower seat pan and cushion. Score! I bought a new RV-8 stick base along with some 4130 steel tube stock and had a local welder fabricate it. I'm happy with it and will keep it... what I didn't keep was the dimensions I used. Oops.

This is almost exactly what I was trying to do, except for the grip. I like this grip, but it's a bit tall - I think it's impossible to use without achieving panel clearance at the front of the panel, rather than having the grip pass below the panel. In the process of figuring that out, I also happen to think that a higher stick would be more comfortable.