Why no trim tabs - either elevator or rudder?

[KDOG]

I've wondered why we can't come up with adjustable trim tabs for the Bee. Darylls' rudder thread spawned my question. Especially the rudder, with the Bees' habit of needing almost full left rudder at takeoff and even needing some left rudder at cruise. I swear I've seen them on other birds. They looked like simple pieces of sheet aluminum bent at whatever angle neccessary going along the trailing edge of the rudder.

As far as the elevators, that would most certainly have to be in-flight adjustable. With the prop wash going right over the H-stab area ( as it should be already!), it would be very influential during different times of flight. I guess they would just be "mini-elevators" really. Thoughts?

[scottessex]

You can add a trim tab, but one of the things you might think about is mounting the rudder so it has a 10 degree offset to the left when the pedals are nuetral. That way you will just have to hold pressure on the pedal in flight, but won't have to have your left foot mashed down the whole time.
All the Bensens were like that, except mounted off to the right because of the opposite direction of the prop.

[KDOG]

I see what your saying . Not a bad idea, I'll have to look into that. By the way, Scott. Have I told you about how cool your sig is? I think I suggested getting that on a T-shirt. But now we gotta come up with one that has gyros in it...

[Alan Coats]

Kevin,

The plans for the Watson tail that is on my Bee show a trim tab. The builder hadn't installed it yet when I bought the Bee, and I haven't dug into the plans enough to know how big, what angle, or how to mount it. I planned on asking for advice on that when I get closer to installing the trim tab. I believe the plans for the Watson tail are available on Ralph's web site.

Alan

[KDOG]

I hope I don't offend anyone by saying this, but I don't think the Watson tail is a good choice to put on the bee. It's just too small in my opinion. I plan on using the Starbee tail or something even larger if I come across the plans for one. The Watson tail looks nice, but it just doesn't have enough surface area -especially vertically- for my taste. But it will still be interesting to see what you do to your bee...

[Alan Coats]

Kevin,

You sure didn't offend me.

Like you, I am a newby at this, so I am going by the feedback of others. I had not heard any negatives about the Watson tail until now. Ralph's mention of it on his site seems to be positive.

I know the rudder looks small, but it does have a pretty large surface area, and being airfoil shaped will make it more effective for its size.

If anyone who has experience with the Watson tail has any comment, please let us (me) hear it.

Thanks,
Alan

[gyropilot]

I hope I don't offend anyone by saying this, but I don't think the Watson tail is a good choice to put on the bee. It's just too small in my opinion.KDOG,

Your opinion on the Watson tail is based on what?

Just how many hours do you have in a Bee and with what type of tail?

John L.

[Doug Riley]

The prototype Watson that I used to have (and John L. now has) certainly had a trim tab. As it happens, Doc initially put it on the wrong side of the rudder, but it worked anyway if you bent it far enough. Yes, the cables should be unequal in length so that the pedals are neutral when the rudder is deflected 10-15 deg. I've done engine-outs with this tail and it was OK. The area is around 4 sq. ft., which is pretty close to the Air Command. I did find myself holding full left rudder in very low-speed takeoffs (a 'Bee specialty). With the tab properly adjusted, you will not need to hold any pressure at cruise. The aircraft should be set up to fly both hands- and feet-off at cruise.

[Brian Jackson]

I think people assume that the Watson's tail is "tiny" because the eye follows the silhouette of it's triangular shape, which appears less imposing than a broad, squared surface, when in fact it meets all the criteria of surface areas needed by the Bee. They seem to fly just great. I have heard that a little more rudder authority would be desirable, but that's heresay. I'm not seeing any mass exodus to another design from those who fly them. The fact that Watson's tail design is so popular should be a heads-up that they probably perform pretty well. Just my opinion.

Thanks,
Brian Jackson

[gyropilot]

And here's the original Watson tail as it now appears on my Bee:

http://home.usaa.net/~gyropilot/Thun/N392JL.jpg

[Alan Coats]

John,

What are the fasteners you used to attach the trim tab? Could a person cut a slot in the back edge of the rudder and epoxy the tab into the slot, or is it more effective attached to the side of the rudder?

Mine looks so slick, I hate to put a bunch of bolts through it to attach the trim tab.

Thanks for posting the photo. It does bring up another question - as I recall, the documentation doesn't mention cable adjusters on the rudder cables. Is there any reason not to? Seems like it would be nice to be able to adjust the pedals to neutral after flying the Bee.

Alan

[GyroRon]

John, does it take alot of left rudder in slow flight? During takeoff and landings?

My pick for a tail on a gyrobee would be a Ron Herron T- tail if I could not find a way to use a tall dominator type tail.

[Dale Young]

Building in a little offset to counteract torque is a great idea. I used a Sno-bird tail on mine. This tail has a built-in offset, which requires VERY little rudder correction at take-off. The only down side of this tail is that the HS is on the small side, although I have'nt experienced any adverse effects from it,

[GyroRon]

Dang Bubba.... that is a sharp looking machine ya got there!!!! Love the colors!

[gyropilot]

What are the fasteners you used to attach the trim tab? Could a person cut a slot in the back edge of the rudder and epoxy the tab into the slot, or is it more effective attached to the side of the rudder?Alan,

Those are simply aluminum rivets you see holding the trim tab on.

I'm sure you could do the slot / epoxy method, but because of the wide trailing edge of the rudder, the trim tab might be more effective if placed on the right side. But then again, if you put it on the trailing edge, all you would need to do is make the trim tab a little larger and it's going to work fine.

Best regards,

John L.

[gyropilot]

John, does it take alot of left rudder in slow flight? During takeoff and landings?Ron,

To be sure it does take some left rudder, but I wouldn't call it "a lot." My Watson tail seems to have a lot of rudder authority anytime the engine is at least 3000 rpm (or greater).

I suspect there may be something else at play here...

If a tail has a large vertical stabilizer, it would seem logical it might be more affected by crosswinds trying to yaw the aircraft... verses the Watson tail with it's smallish vertical stab component. In the case of a tail with a large vertical stab, it would then need correspondingly more rudder authority to compensate for the increased crosswind induced yaw.

Is it also possible that a large / taller vertical stabilizer is affected greater by the swirling prop blast? That would also require more rudder correction.

Maybe the Watson tail just happens to be a good balance of size (both vertical stab and rudder) and placement (location in the prop blast)? Maybe a huge / tall vertical stab isn't necessarily a good thing? I'm not sure if a rudder can get too big, but I suspect a larger rudder could also be affected by crosswinds... although it would have correspondingly more authority to adjust.

My advice to the new GyroBee builders reading this: Stick with the tried and tested and stop trying to reinvent the aircraft before you know what you're doing. The Watson tail is adequate for this model gyro.

Regards,

John L.

[KDOG]

But would you agree or disagree that a tail with more "authority" both horiz. and vert., like the Starbee tail, would be a better choice? Especially for us first time Gyrobee builders. Also, how is adding a rudder trim tab "reinventing"? Theyre as old as the hills.....

[KDOG]

And Dale that IS indeed a nice looking bird!!! Like you stated your H-stabs are a little small, but they seem to be dead on in the middle of your prop wash. Would it be hard for you to fabricate large ones?

[Alan Coats]

Also, how is adding a rudder trim tab "reinventing"? Theyre as old as the hills.....

Kevin,

My point in bringing up the Watson tail was to let you know that a trim tab have been designed and added to the Bee. The Watson plans call for it to be 4" x 7".

Alan

[gyropilot]

But would you agree or disagree that a tail with more "authority" both horiz. and vert., like the Starbee tail, would be a better choice? Especially for us first time Gyrobee builders.I don't agree or disagree.

I have no way of knowing if the tail Star Bee is marketing for the GyroBee is a better choice than the Watson tail until someone qualified puts it through a proper testing program. I don't know who did, or what sort of testing was done, on the Star Bee tail. Before flying with a Watson tail (for 100+ hours now), I did get a flight report from someone qualified whom I could trust.

When it comes to a tail, it's possible more vertical stab "authority" and even a bigger rudder (beyond some point) isn't necessarily better.

Also, how is adding a rudder trim tab "reinventing"? Theyre as old as the hills.....The trim tab was not what I was referring to. My reply to Ron was discussing the performance characteristics of the Watson tail I fly vs. the Star Bee tail he tried out.

Best regards,

John L.

[KDOG]

Oh, never mind!! I got two of you mixed up, disregard!!!

[wimpy35]

Pardon please, Where was the picture taken? Just wondering, I use to go to the Puyallup airport quite a bit.
jim

[Ralph]

The prototype Bee used a KB2 fin/rudder and there was NEVER a problem with adequate rudder authority. Yes, it does require left pedal in flight but nowhere near the "full pedal" that is being bandied around here. If you choose to lift it off at 20-25 mph it will need more pedal - most gyros would - if they could get off the ground at that speed. I once had to do an engine out (off, not idle) approach at 15 mph because I only had a short strip of decent field out front. At 15 mph with no prop-wash there was not trouble holding a heading.

If one has to hold full left pedal it is quite possible the pedals are not set up properly. Using unequal cable lengths to build in the trim setting is fine. We never bothered, but there is no problem doing it that way.

We are putting a StarBee tail on the new Bee but it won't be flying until Spring. Ron flew the "company ship" so is the worlds best authority so far on that tail-group. So far, all of the many rudder/fin combinations used have appeared to work out. I hate to sound like a broken record, but simply build and fly it. Then you will KNOW what, if any trim adjustments you will need to make.

Ralph

[PW_Plack]

Don't forget to consider weight. It would be very easy to "improve" yourself clean out of part 103.

[gyropilot]

Pardon please, Where was the picture taken? Just wondering, I use to go to the Puyallup airport quite a bit.Jim,

That picture was taken with my Bee parked in front of the restaurant on the west side of the field.

John L.

[GyroRon]

I am not saying the Bees were un-controllable or were bad in any way, just that at very slow speeds - Especially as the gyro is balancing on the mains for takeoff and just as it leaves the ground and also coming in for a landing just as it is abotu to touch down, Both gyros I have flown needed either almost full or all left rudder to maintain straight forward flight.

I know barrys bee is not set up per plans, the pedals are set up different, the tail is different. His bee is set up with the rudder perfectly centered on the keel with the pedals even, and the front wheel is straight with pedals even. His machine set up allows more side to side travel or deflection on the rudder and front wheel than had he built to plans.

Does this make his machines set up less than ideal... don't know. But the Starbee gyro flew just like it - only less twitchy on the ground, if while balancing on the mains before take off you allow the nose wheel to touch while holding in all that left rudder.

I also believe I remember Dana saying his tail on his gyro is not exactly how the " production " tails were going to be made or installed or something to that effect.

Look bottom line is the bee is a nice machine and sounds like the Watson tail will work just fine so build that and you should be happy.

[Dale Young]

I have tried to make myself go ahead and fab out a larger HS, But I'm too busy having fun in it. It should'nt be too hard. But I have flown this thing as hard as I think I'll ever fly it, and it still shows no ill effects at all.

[ultracruiser41]

I've noticed that at slow speed the bee needs alot of left rudder as Ron mentioned but mostly due to the fact that the bee doesn't move fast to get off the ground. I installed turnbuckled on my rudder cables and I'm just going to adjust a little left rudder into the set-up which should help the situation.

One thing that is neat about building a flying machine is you can add or modify things to your heart content but remember...Ralph designed a perfectly good machine of which the original is still flying. (I believe) DOn't try to re-invent the wheel before you know how the wheel rolls...it's a simple machine so try not to over-engineer it too much.


BarryK

[Brian Jackson]

...but remember...Ralph designed a perfectly good machine of which the original is still flying. (I believe) DOn't try to re-invent the wheel before you know how the wheel rolls...it's a simple machine so try not to over-engineer it too much.
Amen to that! There's a lot of Bee mods out there that are very capable machines, and it's fun to ponder new ideas and have the ability to experiment with them. That's the nature of "experimental" aircraft. However, as a newbie I've chosen to keep mine stock all the way, with the exception of a few cosmetic curves here and there that don't affect anything structurally.

The one area I'd like to experiment with at some point is the tail. I've always been fascinated with empennage structures and negative lift airfoils, which I suppose is a perfect marriage for a gyro enthusiast! But I completely agree with you. The CAD models I post here from time to time are probably more for my own benefit. Having built the GyroBee in CAD helps me to better understand the interrelation and integration of it's structural members. It's also a part-by-part reference during construction to help prevent costly errors in cutting, drilling, etc.

It's also a very comfortable, cozy feeling knowing that Mr. Taggart's documentation is so accurate dimensionally that many dozens of flying Bees have been built from it.

But as with all sports, it boils down to personality and goals. If the end result is simply to fly, Mr. Taggart's documentation is almost idiot-proof. If your goal is to experiment and tweak, the GyroBee is an excellent canvas on which to render your ideas.

Just a thought.

Brian Jackson