Sometimes it's good for Winter

[lperagallo]

I just spent the better part of the day with JC working on the trusty Intrepid. It started as a Boom replacement (don't ask) from a previous crash. I swear I didn't see it bent until I was flying it.:oops:

Well, JC noticed a loose ball on the swash plate. Great that's the second one....or is the one I replaced a month ago? Did the locktite not hold because I didn't clean it good? OK, so JC saved me from crashing:thumbup:

Next on to slop in the tail. Found a link so worn that you could actually see daylight between the link and ball. Easy Fix.

Then on to the wash out arms. Replaced all the bearings, seems as though I've been hard on the bird this year. OK, so what do you do when it just doesn't seem to go back together right? Call Chris. Then as you explain the problem, Chris asks if I'd followed the manual? Yeah right, like experienced builders ever read the manual.:smokin: I'm then reminded of the grub screw that holds the wash out arm bolt in position for a smooth as silk pivot. OK enough about an hour wasted :bawl

On to the see saw. Just a tad of slop. HMMMM, seems that if I tighten the bolt up on the right, all the play goes away. This time I decide to read the manual. OH NO, it says to use RED lock tight. I used blue. OK so put on the red.

Sure do have a solid machine again. All the maintenance is complete and there isn't any slop anywhere in that bird. Moral to the story......Ask a friend to go over the machine with you so he can find things you've overlooked for a year and as Chris would say RTFM before you call. Saves us all a lot of time.

Big Thanks goes out to JC and Chris for helping. :clappp

[mdelzer]

RTFM, story of my life...

[cbergen]

Mine too.....:)

[cbergen]

By the way, some of these tips and hints are showing up in the Tazer 800 build thread.

http://helifreak.com/showthread.php?t=60211&page=4

More to follow...

[JC]

Uhhh... I didn't know there was a manual. :o
I cant wait to see Lou fly it with the major difference we made on it. It's going to feel good in the air I'll bet.

It was a great day Lou. Had fun.
Now if we could just add about 30* and stop the wind from howling at 30mph...

[v22chap]

JC ----- snicker , snicker :thumbup:

I fall in this department also !!!!!:hug:



Been following the tazer build and noticed a couple things already I need to check on a few birds :whip

[lperagallo]

OK Chris, Thanks to your post on the Tazer, I now have to go look at my wash out arms. Am I advanced or retarded (don't answer that:D). I also found a good article on this phasing thing (swash plate timing) so if I want to experiment I can. I will say that the article on phasing talked about loops and how they perform. It covered my problem loops that end up like a corkscrew. It explains how to mix Aileron and elevator and Elevator and Aileron. I just thought my loops were bad because I could fly it right (again no comments please!). Also seems to explain some of my nose up in rolls in the gasser. Again mixing may help solve that also. It's amazing what you can find on the Internet with the right search.:) Here is a link to the article.
http://www.macgregor.co.uk/helicopters/docs/mixing.pdf Anyone with experience in this feel free to jump in and share more comments on how to set this up.

Boy, just when you think you have it figured out new things come into play.:banana

Lou

[rkeith2]

Not a lot of experience but the advanced retarded comment is sure hard to resist


Very nice article - I like the pictures to

[v22chap]

but the advanced retarded comment is sure hard to resist


You and me both Ron :banana:Bang:clappp

Good find on the articles Lou :thumbup:

[JC]

So Lou calls me and tells me about the info on his washout arms. As I'm driving down the road he tells me he needs to find out if he's advanced or retarded. :D I'm sure you know what I told him. :rolling I had no idea it was going to be this funny until I got home and read more in this thread. I love this place.

Lou is a great friend so I know he knows were kidding him. :hug:

Once we get back to flying, the jokes will be on me... again.

[v22chap]

JC

Lou is a great friend so I know he knows were kidding him
Yep I have had a lot of fun this yr at different funflys with Lou. He comes across a little rough and gruff at first ,,until you get to know him :hug:

And yes I love this place a great deal too.

[lperagallo]

All of this is also called swashplate timing, and in the higher end radios can be adjusted electronicallyin a specific mode or by mixing in some aileron with elevator, and elevator with aileron.

If you prefer to have your swashplate timing set to 0 and have pure aileron and elevator movement, then use the first, suggested setup and mix it out in your radio.


Chris,

For us that don't have a high end radio with a specific setting, what mix do you suggest. I guess I'm not sure of the physics in this, but I assume you need to mix some aileron in when the elevator is pulled. At one time I remember you saying something about 12%. Is that a mix of +12% aileron on a 100% scale? In the Spektrum the rates are from -125 to +125. I checked the swash and positive numbers roll to the left while negative numbers move to the right. It looks as though everything is proportional so small movements of elevator results in a small movement of aileron.

So do you recommend any starting numbers for the Intrepid?

Lou

[cbergen]

Crap, just as I finished the reply the server went down....

I do not have any hard and fast numbers, each heli is a little different. For instance my gasser swash timing is different than my Turbine.

The best way to set it up is to fly it, make an adjustment, try it again.

Do your best roll. Add in a mix of ele to ail and see if it's better. If so, then you're moving in the right direction. If not....Go the other way.

Do a loop either coming right at you or straight away. see which way it corkscrews. Add in ail to ele and see if it's better.

Start with a number that you KNOW will make a difference, say 10%. You have to be able to SEE the change to know if it's effective.

[MarkWebber]

The best way to set it up is to fly it, make an adjustment, try it again.


It was difficult for me to decide which way to adjust the phasing(I cheat and adjust in the AP2000i:)). I wasn't sure if the heli was needing right or left cyclic in a loop. So I purposely added roll to a loop in the sim to get it in my head how it worked. About 10 degrees left took the interaction right out.

It was nice to do loops/rolls without thinking I was adding the improper control movement.

[JC]

OK I'm trying to wrap my brain around why this is needed. Wouldn't these mixes effect everytime you pull elevator or whatever input your mixing? I mean not everytime you use elevator your doing a loop or roll.
Is this phasing "problem" only on some swash types?

I clearly have some more reading to do. :thinking

[cbergen]

JC,

Look up gyroscopic precession.

We normally say that a control input happens 90 degrees "out of Phase" or 90 degrees later. This number is closer to 82 degrees IIRC.

This Phase is what we're adjusting.

Remember that this mix is also proportional, a little elevator gets you a little ail mix, a lot of ele gets you a lot of ail.

With the electronic systems now available such as the Spartan or V-stabi, they induce this swashplate timing electronically, where previously with a flybarless head, we had to set the timing mechanically by rotating the swash and securing it with a follower.

This can be seen by the exaggerated(sp?) angle of the pitch rods from the swash to the blade grip.

Discussion?

[mdelzer]

Now if we could just add about 30* and stop the wind from howling at 30mph...

Man, and I WANT to move to SW Michigan from SoCal. I must be insane or it's my Montanan blood....

Mark

[JC]

Man, and I WANT to move to SW Michigan from SoCal. I must be insane or it's my Montanan blood....

Mark:rolling
Hey Mark, maybe we can just trade localities for a few weeks a year. Right about the middle of January would be good for me to take a break from the snow. I'll come bask in your sunshine... go to the beach, etc., and you can come build a snowman, go snowboarding, and shovel the driveway. :smokin:

Jeff

[JC]

JC,

Look up gyroscopic precession.

We normally say that a control input happens 90 degrees "out of Phase" or 90 degrees later. This number is closer to 82 degrees IIRC.

This Phase is what we're adjusting.

Remember that this mix is also proportional, a little elevator gets you a little ail mix, a lot of ele gets you a lot of ail.

With the electronic systems now available such as the Spartan or V-stabi, they induce this swashplate timing electronically, where previously with a flybarless head, we had to set the timing mechanically by rotating the swash and securing it with a follower.

This can be seen by the exaggerated(sp?) angle of the pitch rods from the swash to the blade grip.

Discussion?Thanks for the info Chris.
I think that discussion may make my head hurt. I'll be a fly on the wall for a while while that conversation goes on... but I certainly welcome it.

I'd start a new thread on the topic but I'm not sure what to ask that would lead to a meaningful discussion. Anyone? Ah... I see Lou in the back there has his hand up. :)

[MarkWebber]

The part of the discussion that I've yet to get answered for me elsewhere is this:
Is gyroscopic procession affected by HS? I'm not a good enough pilot to be sure that I wasn't introducing some interaction myself. But, it did seem as HS was increased, the previously neutral heli would then have just a bit more procession interaction.

Thanks for your thoughts, Chris.

[cbergen]

Some of the best reading I have found on the subject, and I refer back to it often, is from Colin S. Mills of CSM gyro fame.

The complete set of articles are here, http://www.w3mh.co.uk/articles/articles.htm , scroll down to the bottom. They are reprints from magazine articles from some time ago, but still relevant today.

Specifically what we are discussing here is in part 11.

Part 11

In the last few articles we have seen how cyclic control of the pitching and rolling motion of the helicopter is accomplished and how Hiller and Bell-Hiller control systems allow the response of the helicopter to cyclic control to be tailored. We saw that, for freely flapping blades the maximum cyclic pitch must be applied 90 degrees before the required high point of the flapping. In other words, for a clockwise rotor a right roll is caused by having maximum cyclic pitch as the blades cross the boom, and nose-down pitching is caused by having maximum cyclic pitch on the retreating side of the rotor.

In the May issue I mentioned (when considering forward flight) that offset flapping hinges and damper rubber stiffness change the way in which the blades flap, and that they could cause a roll tendency in forward flight. Cyclic control response is also changed by flapping hinge offset and damper stiffness. They cause the high point of the flap to occur earlier, that is, less than 90 degrees after the maximum cyclic pitch.



In this illustration we see what happens if we continue to apply the cyclic controls 90 degrees ahead of the required motion. Notice how the right roll command now additionally causes a nose down pitching motion. To combat this the control system needs to feed the cyclic inputs in later in the rotation. This can be done by rotating the swash plate in the direction of rotation. With the cyclic controls retarded in this way the correct response to cyclic inputs is obtained as seen below.



Phase errors and the control system

The Hiller and Bell-Hiller control systems have the effect of reducing these cyclic control phase shifts and so many model helicopters make no provision for rotating the swashplate. The flybar in the control system is freely rocking and pivoted on the axis of the main shaft (the equivalent of having zero flapping hinge offset) so it does not suffer the sort of phase errors just described. In the Hiller control system the cyclic control to the main blades comes from the flybar and any tendency for the blades to misbehave (pitch up or down during a roll command for example) is suppressed. This happens because any angle between the plane of the main blades and the flybar causes a correcting cyclic control to be fed to the main blades to make them follow the flybar. If in a roll the main blades start to pitch nose down the nose down attitude of the main blades relative to the flybar will cause some nose up cyclic control to be fed to the main blades opposing further nose down movement. The same happens with the Bell-Hiller system but because a proportion of the cyclic control of the main blades taken directly from the swash plate, the degree of phase error suppression is lower. Where the mechanics provides the facility, residual phase errors can of course be removed by rotating the swashplate as mentioned before.

[cbergen]

Mixing in ail to ele and vise versa is effectively the same as rotating the swashplate or changing the radius links on the washout unit, OR using one of the electronic flybar systems....

[mdelzer]

:rolling
Hey Mark, maybe we can just trade localities for a few weeks a year. Right about the middle of January would be good for me to take a break from the snow. I'll come bask in your sunshine... go to the beach, etc., and you can come build a snowman, go snowboarding, and shovel the driveway. :smokin:

Jeff

It looks official, I'll be moving to either the Novi area or he New Buffalo area of Michigan soon. I just have to figure out which one I like better over the next 4 or 5 months while I work from the Grand Rapids area. I don't want to take this thread OT, but a lot of the people replying are all in the areas so please PM me with any responses. I do have a few questions, one option is for me to live just on the other side of the border in Michigan City, anyone know of any advantages or disadvantages to this both taxes and expense wise? I know that even coming from California my 6 month premium for car insurance for my 2 cars went up $1,100 living in the Grand Rapids area. Novi also looks to be like it is one of the better neighborhoods in the Detroit area, but non the less Detroit is still considered the number 1 worst city in America to live in. Anyones thoughts on the areas would be GREATLY appreciated.

Mark

[mdelzer]

I took it a step further and started an off topic thread. http://www.helifreak.com/showthread.php?t=63122
Thanks in advance for anyone that might have some advice.

Mark