rudder trim ?

[fairchild1934]

has anyone in the experimental community (or bearhawk) tried building a simple rudder trim mechanism ?

I was wondering if one could be designed using a small 12 volt gear motor and have the motor mounted at the bottom of the rudder post.
Have to think about how to transfer the motion up through the post and turn it 90 degrees for the tab......
It shouldnt take a whole lot of motor if its geared way down----- wouldnt a large RC servo do the job ? :-)
wouldnt those have a buit-in pot to feedback the position to the cockpit indicator ?

Tim

[alaskabearhawk]

Kelley Babin in Oklahoma installed a Piper trim system in his. It was a long time ago that I had heard anything about him.

http://www.mykitlog.com/users/display_log.php?user=kbabin&project=148&category=0&log=46114&row=3

http://www.stevesaircraft.com/ruddertrimstc.php

I don't know why you would want to make a complicated electrical system for rudder trim. Most just put a bendable tab on the trailing edge of the rudder. In my experience once the rudder trim is set you pretty much never have to mess with it again. The GA aircraft that I have seen have the elevator trim wheel nice and polished through use, but the rudder trim wheel just collects dust. But, if that's what you want to do, good luck.

[jaredyates]

I think the spring bias up front is much less complicated than a moving tab in the back. If you use a Ray Allen servo it also has position reporting.

[500AGL]

Less complicated and safer.

[fairchild1934]

never flown something with a cockpit adjustable rudder trim. If it hardly gets moved- there would be little point I guess. I has seen the STC for the piper one using the small stainless cables. Will look up the ray allen servo just for fun-

Jared- "can you tell me what "the spring bias up front" refers to -- just for my FYI ?

[fairchild1934]

never mind Jared---- I see what it is NOW --- :-) I agree----

[Battson]

There have been threads about this in the past, you should be able to find some hopefully. People have shared drawings and 3D renderings etc.

I don't know why you would want to make a complicated electrical system for rudder trim. Most just put a bendable tab on the trailing edge of the rudder. In my experience once the rudder trim is set you pretty much never have to mess with it again.

I know that IFR and stable long distance cross country platforms benefit from rudder trim, but the Bearhawk is not that kind of aircraft.

I spent a lot of time thinking about this when I was building. But now I have been flying for a long time, I never (never!) find myself wanting rudder trim controls in the cockpit. The Bearhawk is not a feet-off-rudder kind of design. More of a "pilot's design" - an aircraft which likes to be flown.

[kestrel]

I don't see why the Bearhawk isn't an IFR aircraft. I agree that for general flying around, cockpit rudder trim isn't needed. However, the setting that works well when light and local does NOT work when heavy. When flying heavy for a long distance, holding rudder for hours on end is just miserable. ...and if you don't keep it just right, fuel doesn't feed evenly. Now roll is also out of whack. ...so, I end up not using "both" on my fuel selector...

Be careful about projecting your own circumstances on others. We don't all do the same flying or have the same triggers.

[Battson]

I don't see why the Bearhawk isn't an IFR aircraft.

Nev you can answer that better than I can, I believe I am quoting you.

[Battson]

Be careful about projecting your own circumstances on others.

I have no idea what you're talking about?

I don't think the level of stability in an aircraft design has anything to do with one's "own circumstances" - it's factual. Maneuverability and stability trade off against each other, like speed and fuel economy. The Bearhawk is a highly maneuverable aircraft, hence it's not a particularly stable platform, and especially as the CG moves aft.

I've done dozens of hours day and night IFR in IMC, probably close to a hundred hours controlled VFR. It isn't much fun in a Bearhawk in my opinion - save for a well-tuned autopilot, which has proven difficult for some people to achieve.

I think it's a pretty well accepted fact that the vast majority of pilots prefer a stable aircraft for IFR flying. Maybe you have a different opinion, which is great - that's what forums are for. Could you share some information?

[Battson]

Tim - you may find these threads helpful:

https://bearhawkforums.com/forum/tools-technics-and-best-practices/25452-rudder-trim-tab

https://bearhawkforums.com/forum/bearhawk-general-discussion-news/36730-electric-rudder-trim

https://bearhawkforums.com/forum/bearhawk-general-discussion-news/30813-rudder-trim-tab

https://bearhawkforums.com/forum/tools-technics-and-best-practices/10527-adjustable-rudder-trim-mod

[schu]

I have no idea what you're talking about?

I don't think the level of stability in an aircraft design has anything to do with one's "own circumstances" - it's factual. Maneuverability and stability trade off against each other, like speed and fuel economy. The Bearhawk is a highly maneuverable aircraft, hence it's not a particularly stable platform, and especially as the CG moves aft.

I've done dozens of hours day and night IFR in IMC, probably close to a hundred hours controlled VFR. It isn't much fun in a Bearhawk in my opinion - save for a well-tuned autopilot, which has proven difficult for some people to achieve.

I think it's a pretty well accepted fact that the vast majority of pilots prefer a stable aircraft for IFR flying. Maybe you have a different opinion, which is great - that's what forums are for. Could you share some information?

Let me help explain what he is talking about.

His experience is that the bearhawk requires different rudder trim when heavy vs light, thus you either hold the rudder on light local flights, or on long cross country flights which is miserable, and if you ignore it, you get poor fuel balance.

You completely dismissed his point and asserted that the bearhawk has a stability trade off and not particularly stable, which is to say that it isn't well suited for long cross country or IFR flights. That is effectively projecting your own circumstances on others because your mission given where you live probably means you won't travel more than a state or two away from home base.

As someone that has flown a light airplane as far West as Platinum Alaska, as far North as Tok Alaska, as far east as Oshkosh Wisconsin, and as far south as the Mexican border, I assure you that my mission and experience is very different than yours. I have spent days holding a rudder peddle dealing with weather.

Some of us are looking into ways to make the Bearhawk a better XC airplane, either with an auto pilot, additional rudder trim, removing the servoing trim system, etc only to be told that we don't need it or it wasn't designed for this mission.

Anyway....... I'll post my solution:

I just put in a 3 axis autopilot. With the 3rd servo on the firewall making a loop out of the rudder system. If I need rudder trim, I'll just hit the yaw damper button or full auto pilot. While I for sure don't need help flying a tailwheel airplane, I plan to use this thing as the family airliner, so cruise control makes sense to me as I'll be doing 3-4 hour legs and possibly 7-8 hour days with this thing regularly.

schu

[kestrel]

I don't think the level of stability in an aircraft design has anything to do with one's "own circumstances" - it's factual.

Agreed. ...but this thread is not titled "rudder stability", it is titled "rudder trim".

I think it's a pretty well accepted fact that the vast majority of pilots prefer a stable aircraft for IFR flying.

I agree that this is a factual statement. Unfortunately, it also missed the point. Note that it is pretty well accepted that the vast majority of pilots perfer a nose wheel. That doesn't mean that I do or that I should tell others that they are wrong if they prefer a tail wheel.

I'd far rather fly IFR or any long distance cruising in an airplane with limited stability, but correct trim than one that is very stable but out of trim. In fact, the less stable an aircraft is, the more I care about having perfect trim. If you feel differently, I'm not going to tell you that you are wrong or ridiculous. We are all humans, each different, each with different preferences.

I know that IFR and stable long distance cross country platforms benefit from rudder trim, but the Bearhawk is not that kind of aircraft.

That may be true for you, but don't project this on others. For me, the Bearhawk is a long distance aircraft. I don't have the luxury of fantastic mountains and the backcountry flying that you do daily without a 2,000++ mile flight to get to it. New Zealand can be flown from tip to tip in half that distance and I don't mean the straight line out over the ocean. ...and on the rare occasions that I get to do such a trip, my airplane is FULL. My family and all of our gear for a couple of weeks is in the airplane with me.

So, is the Bearhawk "not that kind of aircraft"? ...am I wrong if I fly my Bearhawk long distances and to me it is "that kind of aircraft"? Am I wrong if I think there is value in having an aircraft of limited stability in proper trim when flying for long hours over long distances?

[Battson]

I allegedly said "you're wrong" (or words to that effect) many times. Try and quote it please, you'll find I never said that. I've just made some observations, and offered an opinion that the Bearhawk is a fairly maneuverable aircraft. No need to worry about it!

If my experience doesn't align with your mission or experience, please don't interpret that as an attack on your mission philosophy or experience. We're allowed to have different opinions

This reply of mine isn't a useful post, it's deteriorating into an argument online. Maybe better not to answer...

[Battson]

His experience is that the bearhawk requires different rudder trim when heavy vs light, thus you either hold the rudder on light local flights, or on long cross country flights which is miserable, and if you ignore it, you get poor fuel balance.

You completely dismissed his point and asserted that the bearhawk has a stability trade off and not particularly stable, which is to say that it isn't well suited for long cross country or IFR flights. That is effectively projecting your own circumstances on others because your mission given where you live probably means you won't travel more than a state or two away from home base.

As someone that has flown a light airplane as far West as Platinum Alaska, as far North as Tok Alaska, as far east as Oshkosh Wisconsin, and as far south as the Mexican border, I assure you that my mission and experience is very different than yours. I have spent days holding a rudder peddle dealing with weather.

Some of us are looking into ways to make the Bearhawk a better XC airplane, either with an auto pilot, additional rudder trim, removing the servoing trim system, etc only to be told that we don't need it or it wasn't designed for this mission.

If my experience doesn't align with your mission, or differs from someone else's experience, please don't interpret that as an attack on your mission philosophy, or on their experience. That is not my intent. I am often hurried in my posts as it's hard to find time... I get these are homebuilt aircraft, the aircraft, mission, and thus experiences will often be different.

I think the Bearhawk can definitely do a fine job of long cross country, but I think most would agree it's not the best possible aircraft for pure cross country only. Probably the best for cross country in the backcountry... some might say. Our missions may not be totally different Schu, I have done a LOT of long cross country it in my Bearhawk, regularly to the limits of it's range, and often needing many tanks of fuel over several days. Once I got all the rigging issues sorted, I have never noticed the rudder to be a bother, once the fixed tab was tuned. Mine flies hands free. Clearly some do notice the rudder and see it as a problem, at least now we have all that experience recorded here so people can make better decisions.

My circumstances have nothing to do with the "stability trade off" which is a constraint for any aircraft design. More stable aircraft are usually less maneuverable, such is my understanding but I'm no designer. All I can say is how the plane flies in my experience, and I find it relatively maneuverable. I can say lots of experienced IFR pilots who fly a Bearhawk with me say "its not a great IFR ship". Others may disagree. Again, this is nothing to do with my circumstances, that's just my experience of flying Bearhawks.

I never said "it wasn't designed for (cross country / IFR)" so far in this discussion, I didn't event mean to imply it yet - it was designed for cross country at least. But if wasn't designed for IFR, then so what? It's not meant to be a Bonanza, it's a STOL machine that can do cross country and agility flying, that is also able to do a bunch of other things. If you're building a fast IFR ship that can land somewhere short - awesome - but that doesn't mean everyone else should think it's a great IFR ship.

I never said it "cannot" do IFR, my machine's sister ship was built for IFR and I enjoyed flying it on autopilot. I hope you come back in 10 years time to say "I've done a decade of IFR in my Bearhawk and it works great". You can even thumb your nose at me

[Battson]

jaredyates maybe need to cut half of this out into a different thread...

[Mark Goldberg]

One thing not mentioned in this discussion is the difference between airplanes and how they each fly. All Bearhawks do not fly identically because they are experimentals built by different individuals with different abilities or determination to properly rig their planes. Also added to the mix are plans built plans versus the kit built planes. Just quite a bit of room for variation in how they all are built and how they fly. All might be Bearhawks, but my observation is there are often differences in how they fly and the "stability" each one demonstrates. Mark