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Some notes from the Twister's trimming.

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Some notes from the Twister's trimming.

Post  RknRusty on Mon Aug 08, 2016 11:10 pm

I spent the evening indoors tonight working on the decal for Wayne's Cavalier. It came out pretty nice, and at 6.25" tall and 5" wide it should look nice on the inboard wing Tomorrow I'll work on my own wing art for Taz.


Before the first flight, we all know there are checks and adjustments confirm the plane is stable in flight and not going to fly straight into a grocery bag. The pre-maiden trimming of my Twister last week went as follows:
First is to hang the plane by an allen key or small rod from the leadouts and make sure we see 1-2 degrees of nose down attitude, the vertical CG. I had to slide the leadouts significantly aft(from the plan's position) to see any change at all. After I finally got 1 degree of nose-down, I left it like that. Had I not, loose lines would have plagued the first flight. This is the one part of the yaw we are adjusting, and in flight, especially the first, you can and should check this by looking at the wheels as it flies level laps. The outboard wheel should be partially visible peeking out from behind the inboard wheel. This indicates the plane is yawed slightly to the outside of the circle and helping maintain line tension.

For Horizontal CG, balancing the plane in the same position, wings held vertical and supporting it by holding the plane at the nose and tail, revealed no tendency to roll in either direction. When they do roll, it's usually toward the belly-down position. No adjustment was needed on this one. If necessary, lighter wheels may be helpful. I'm not 100% sure what the symptoms would be, except possibly hinging at certain attitudes in maneuvers as if tip weight was lacking. Don't mistake one problem for the other... I'm still learning.

In my maiden trimming report, I mentioned something I learned about tip weight. On my first flight, I ran an MA 10x4 prop. The plane flew with the outboard tip low both upright and inverted. It was so anemic I changed the prop to an APC 10.5x4.5 and it really woke up. The added inertia and resulting gyroscopic precession of the bigger and heavier prop caused the plane to torque roll in the opposite direction of rotation. The plane now flew wings-level both upright and inverted, so no tip weight adjustment was needed. The prop corrected the wing dip. Something to keep in mind while trimming. If you change props, recheck for level wings.

On a side note, there was some concern that the bigger APC prop was too much for the FP.35. But after fixing a plumbing problem from Thursday(I'd forgotten to plug the OF vent while running on pressure... Duh), I got a perfect stunt run all day Sunday, and as I mentioned earlier never had to touch the needle from beginning to end. I got 12 laps after the clover with a full tank. That was on a 98 degree day, and I'll leave it alone for now. Also she's flying at 5 seconds on 61' lines, eyelet to eyelet.

You need an outside observer to get the best read on level flight. A skilled observer can follow the lines and imagine them as an extension passing through the plane and out the other side. About 5 low flat laps, both inverted and upright are necessary for a good read. If you have no observer, from the pilot's position, look and see if the bottom or top of the outboard wing is visible. It should stay hidden by the fuselage. Also see if the outboard wing presents itself in some snap turns and lazy 8s, which would indicate hinging. This happens if one wing is too heavy or light.

Other than the excessive flap throw, which was corrected for Sunday's flights, I believe the trimming I describe here, with Wayne's help, made a huge difference in the confidence I had in this plane after its first day in the sun. Particularly the vertical CG, which was so far off before we checked it, gave me stronger line tension and even a good tight pull when it was straight overhead. I know lots of the stunt pilots will tell you to move the leadouts forward to help overhead tension, but I'm no longer blindly following this line of thought. In fact, when I try to imagine what happens, it seems wrong. For whatever reason, I'm glad I took the time rather than just tossing it into the air and hoping for the best. There are some great articles by paul Walker and others on Flyinglines.org which are worth studying before launching your next build.

Just a few interesting notes to keep in mind for making a better flying plane.
Rusty

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Re: Some notes from the Twister's trimming.

Post  getback on Tue Aug 09, 2016 8:20 am

The Decal looks good ! and Thanks for the food for thought before launching that next build in the air , as a lone builder accept for the help from the Forum it can really be difficult sometimes to remember or know what to check and do to have a good flying plane . Glad to hear you are getting some good pattern fly's with the new plane This Site Rocks!
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Re: Some notes from the Twister's trimming.

Post  Ken Cook on Tue Aug 09, 2016 3:29 pm

Whenever your looking for pre flight to do's, always give your plane a roll on a smooth floor to insure the plane is tracking on it's gear correctly. The gear wire can be tweaked to compensate for out rolling attitude. In turn, you could also provide some drag on your outboard wheel by tightening your wheel collar against the wheel. This also makes for a good landing which doesn't cause the plane to roll inboard. Check the ground where your launching for twigs, high tough grass or line snagging. Lift your handle lifting your lines well above your head prior to signalling launch.
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Re: Some notes from the Twister's trimming.

Post  RknRusty on Tue Aug 09, 2016 9:57 pm

Ken Cook wrote:Whenever your looking for pre flight to do's, always give your plane a roll on a smooth floor to insure the plane is tracking on it's gear correctly. The gear wire can be tweaked to compensate for out rolling attitude. In turn, you could also provide some drag on your outboard wheel by tightening your wheel collar against the wheel. This also makes for a good landing which doesn't cause the plane to roll inboard. Check the ground where your launching for twigs, high tough grass or line snagging. Lift your handle lifting your lines well above your head prior to signalling launch.
Good tips that I in fact practice since learning it a couple of years ago. When I assembled the pre-bent wire struts and wheels, one was a slower rolller than the other, so I purposely put it on the outside.

In my Sunday report, I didn't follow up on the fairly good landings I mentioned in Thursday's maiden flights. As y'all may know, it's been a nemesis maneuver for me forever now.

So far I have 10 flights on this plane and I have yet to have a bad landing. And Sunday I actually greased one. Good steady descent still good speed at touchdown and a zero bounce rollout. I gave myself a 40, but my judge said easy mid 30s. I accuse him of bracketing, Lol. last winter I started trying to make quality takeoffs, and have gotten pretty good with them. I made takeoff 30s in every flight at Huntersville in May with a couple of pretty tough judges. I still hit 5' too soon, but am getting good rollouts and steady climbs, but still climbing too fast when I hit the headwind. I made a lot of 30 plusses on other maneuvers in Huntersville too, but I invariably throw points away in others.

I just now came in from the shop from repainting where the red had separated along the fillets. Hopefully this time it will stick. I've been flying with the bad spots covered with scotch tape. I'll spray it with clear in a few days. Hopefully I can have it ready to fly it Sunday.

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Re: Some notes from the Twister's trimming.

Post  RknRusty on Fri Aug 12, 2016 10:54 pm

The flaps neutral is a skinny hair off after moving its link to a higher hole in the horn. Remember, I swapped the two rods' connections at the front horn to reduce the extreme flap throw, so I plan to re-adjust it tomorrow. I'm also going to replace the clevis on the front of the long rod with a ball link, but this brings up a question. With ball links at every point in the controls, I will have Zero lash(a.k.a. slop) in the system. I believe a lack of some lash can cause the plane to resist grooving. Anyone think I should replace one of the ball links with a Z bend through a slightly oversized hole? Under the elevator, maybe? Logic says to do it at the flap horn, but that would look sort of goofy. I probably should have done it at the bellcrank, but I didn't like the angle the rod took from that point.

The humidity has gone back up to our normal dog-breath levels, so I brought it into the house for the new red paint on its belly to gas off faster, I sprayed the red very lightly this time, and I'm going to spray some Lustrekote on it in the morning.

Going flying Sunday afternoon
Rusty

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Re: Some notes from the Twister's trimming.

Post  Cribbs74 on Fri Aug 12, 2016 11:50 pm

Slop usually causes hunting. I'd just re-adjust what you already have and try it.

I'm hitting the field tomorrow AM. Temps will be in the 80's humidity 50% or so... Very Happy
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Re: Some notes from the Twister's trimming.

Post  ian1954 on Sat Aug 13, 2016 4:46 am

I have no experience of trimming a CL stunt - only RC and that is simple - twirl a few knobs.

I have watched just about every Windy video. I think this one may be the relevant one.

https://www.youtube.com/watch?v=jLsARl9E9mg

He always leaves slop in the elevator. He sets it at neutral with some tubing in the horn and then removes the tubing.

I assume that the elevator will then find its own adjustment in relation to the flaps. I can't imagine that this is a good idea on an elevator only model and on rc models everything is infinitely adjustable while in the air.

Ron's experience is hunting with slop and I wouldn't contradict this. I suppose there are many variables too numerous to mention but all dependent on the layout of the model.

I am watching these postings and the comments with much interest. After my foray in CL, albeit electrickery, with 1/2 A, I am moving up to 1.5/2.5cc(equiv) models before I embark on the big boys toys.
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Re: Some notes from the Twister's trimming.

Post  Ken Cook on Sat Aug 13, 2016 1:40 pm

I don't mean to sound contradicting, but I found a little slop actually prevents hunting. If the hole is too tight, small inputs from the handle can actually stick and hold until the next opposing input. I would throw some nose weight on the plane and fly it again. It sounds as if your plane is borderline tail heavy. Ken
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Re: Some notes from the Twister's trimming.

Post  RknRusty on Sat Aug 13, 2016 2:19 pm

It has the CG aft of the plans, but as it is, I like the way it flies. There's currently no hunting, that was only on the first two trim flights, and none since then. I was just thinking ahead to when I replace the clevis with a ball link, which will take up all the slack. Right now, the slop is a half millimeter or maybe even less.

Regarding the need for a tiny bit of ... let's call it Play. It's not possible for most humans to keep it in the groove if minute self-correction can't take place, which is what a little elevator play allows
Rusty

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Re: Some notes from the Twister's trimming.

Post  RknRusty on Sat Aug 13, 2016 9:53 pm

Thanks, Ian, that is a really helpful video. I've been watching it on and off all day, whenever I get a chance to sit in front of the computer.
Rusty

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Re: Some notes from the Twister's trimming.

Post  Cribbs74 on Sat Aug 13, 2016 10:58 pm

I was thinking slop in the bellcrank. My full fuse Twister has that problem and that dog hunts.
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Re: Some notes from the Twister's trimming.

Post  RknRusty on Sat Aug 13, 2016 11:23 pm

There's not a worse place to have a control problem than the bellcrank. Major surgery. I've never seen a full fuse Twister. Mine's getting some more exercise tomorrow afternoon. Hitting the field about 3. It's about ready for pattern flying now. I may or may not mess with the linkages before we go. I really should, putting it off won't help me get down to business with this plane.

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Re: Some notes from the Twister's trimming.

Post  Ken Cook on Sun Aug 14, 2016 5:53 am

Rusty, why do you have to open up the plane? Maybe I haven't read into it far enough, did you place the pushrod in the incorrect hole? Profiles are pretty simple to access internally over a full bodied plane obviously. In the event you need access, I mark out the sheeting. I then cut by laying the knife at a 45 deg angle all the way around. Once your ready to glue it back, no need for any additional scabs and pieces of wood, just lay the sheeting back into the cut and glue. Sadly, many of Windy's planes have been lost due to crashes, the Spitfire being one in the foreground. I had some of the pieces of that plane a few years ago.
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Re: Some notes from the Twister's trimming.

Post  RknRusty on Sun Aug 14, 2016 9:06 am

I don't have to open my plane up.
Ron said his full fuse Twister had a sloppy BC connection and may be the cause of his plane's excessive hunting, and I was commenting on that.

My BC has a ball link on it, it's fine. I built good guts.

I have Zero problems with my plane. It is 100% competition capable right now this morning. I just want to replace the only clevis(on the elevator rod) with a ball link, for the sake of safety, and wondered if removing that one and only bit of extremely minor play in the controls might cause any flyability problem. Without that clevis there will be ball links at every connection.
Rusty

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Re: Some notes from the Twister's trimming.

Post  pkrankow on Sun Aug 14, 2016 9:24 am

If it is already "competition ready"

DON'T MESS WITH IT!!!

Phil
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Re: Some notes from the Twister's trimming.

Post  getback on Sun Aug 14, 2016 9:27 am

That was Loud lol! lol! If its for SAFETY then Do It and fly , let us know what good/bad comes from it if any , are you going to give us a look at that baby in the air ? I hope ya'll have a great afternoon of flying . Eric sunny
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Re: Some notes from the Twister's trimming.

Post  RknRusty on Sun Aug 14, 2016 12:28 pm

Lol... Y'all. I'm sorry. I am unreasonably grumpy first thing out of bed. I'd just started on my coffee when I wrote that. Headed out to preflight now. See y'all this evening.
RUSTY! lol!

Went to see Star Trek with my son last night.

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Re: Some notes from the Twister's trimming.

Post  pkrankow on Sun Aug 14, 2016 1:06 pm

(I'm not rereading the build thread right now, but did you leave access hatches or did everything get glued and sealed shut?)

In any case if this is competition ready and the clevis in question is not actually a concern for failure in the next 100 flights, don't mess with it till the end of the season, or the end of next season even.

If there is some real safety concern that involves failure of some part in this system then change it.

Phil
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Re: Some notes from the Twister's trimming.

Post  RknRusty on Sun Aug 14, 2016 9:13 pm

No, I didn't leave any access into the center sheeting, but everything inside is built right. There was a misunderstanding this morning after I commented that it would suck if Ron had to cut his full fuse Twister open, and I think Ken thought I meant my plane. It was too early for me to be posting this AM, and I am sorry I got grouchy and inflated my text.

All I was talking about is that I used ball links and a CF rod from the BC to the flap horn. It also has a ball link at the elevator horn, but I ran out of ball links and used a clevis to hook the elevator rod to the flap horn and I plan to replace it. That's all I was talking about. I don't like the clevis, and also wondered if removing the small slop it allows would affect the plane's ability to groove. Ball links allow no slop at all. I bought new links Thursday, just haven't installed it yet.

The only trimming I did today was to give it more elevator throw. I still think it has too much flap throw, but I'm not going to bore out the top hole on the nylon horn to change that. I'm going to switch to a steel Sullivan horn, and then take care of the flap throw.

In any case, the plane flies really well, so I'll write more about it in my flight report. Movies and pictures too
Rusty

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Re: Some notes from the Twister's trimming.

Post  RknRusty on Tue Aug 16, 2016 10:18 pm

Here is a follow up on the saga of the clevis/ball link discussion and the reason for it being such a squirrelly plane back on its first day of flying:
What's wrong with this picture?


Of course it gives more flap than elevator throw, a lot more. I must've walked over and checked the plans a dozen times, I just couldn't believe it. But everything about this kit has been nothing but excellent, so I went with it... until early in my first flight. You may recall I said it flew like a combat plane. It would turn a loop like a Baby Flite Streak Lol. If it was for sport flying, I think I might leave it that way, it would make for terrific fun snatching it around in the sky.

Then swapping the two connectors threw the adjustments off. To add insult to confusion, I couldn't use two consecutive holes in the horn as the plans indicated for the two rods. The nut on the ball link was in the way, so after reversing the links from the illusration above, I had to drop down another hole, reducing the elevator throw more, so in turn I moved the link under the elevator an extra notch closer to the hinge, in turn accelerating its motion... I think... simple physics, I need to think about it when my mind is in math mode. They make a 4-40 nut with a smaller outside diameter that may not be an obstruction, but I didn't have one.

After all the disconnecting and reconnecting stressed the clevis, which I replaced before flying it again, I didn't like the way it fit. The silicon tube retainer couldn't be slid up far enough to be effective at all, without jamming against the horn, so that's what  led to my decision and posts in this thread about replacing it with a ball link. I finally got to the hobby shop to get some, and will replace it during my next shop session, and I can finally feel safe, but I still hope removing that bit of play from the linkages doesn't affect its ability to groove. It'll probably be fine.

Next time she hits the field, it'll also have its new lettering, numbers and checkerboard.
Here's its name. I drew it in pencil and then Charles "Avaiojet" of CFC Graphics on Stunthangar reproduced my drawing with laser cut vinyl, and I applied it last night. I asked for silver color, and he gave me black and red in addition, as well as my AMA numbers. I had trouble drawing the capital "T" so he made one from a computer font
Now tell me, what does it say its name is?

I think it looks great in the sunlight. Really bright and silver.


I might have to alter it depending on y'all's answers to that question. Here is my original drawing:



Okay, any more trimming will be minor and included in my flight reports. I have learned a lot building this plane, and I can't thank everyone enough for pitching in with ideas and suggestions. Now I'm off to make another movie and finish Sunday's flight report. I started it this afternoon and may finish it tonight, but I need to start hitting the sack earlier than I have been on Tuesdays and Thursdays for a long time now.

See y'all in the funny papers.
Rusty

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