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That is one of the things I have noticed is different with my new flybar. The wings do not want to change position and are more stable in their own flight path, so if they are pushed 10 degrees off the plain that is 90 degrees to the main shaft, they will slowly return to the 90 degree plain instead of bouncing back and forth. In theory, because they are the same total weight as the original flybar weights, the should react the same. This is the only explanation I have for why they are some much different. Although the stock fkybar makes this heli extremely stable at lower speeds, I think it is what creates issues at high speed with the heli becoming unstable and lack or response. |
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The Netherlands, UT, Nieuwegein
Joined Sep 2012
78 Posts
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Australia, QLD, Brisbane
Joined Aug 2012
451 Posts
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Interesting that others find problems with 'bouncing' in flight.
I thought that this was just due to some of my more extreme mods, but still was hesitant to personally recommend the F45 to Solarcow for FPV because of this. For anything else, the F45 is tops. But in view of previous experience with the F39 (very stable as a camera platform in very LIGHT winds) and now the Trex 450 (sits like a rock in attitude, though trying to dash off without constant attention like all flybar CP) - just don't know. I guess BThirsk may have hit the nail on the head. Alas, no real solution suggests itself. Rexless - Get better soon! |
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The bobbing of the flybar is simple air resistance against those round weights. That head design was meant for 7" helis that weigh 2oz. Scaling it up to 2 feet will have undesirable side effects. Using paddles instead of weights gives the flybar a lot more authority to resist change in it's plane of rotation. Regardless of weights or paddles, it doesn't want to change. All objects will resist changes in their plane of rotation; that's simple physics you can easily verify. The 45° flybar follows the head in gyroscopic precession and lags the swashplate movement by a lot. So it's always late and reduces head movement by up to 50% for every rotation.
Imagine you and your brother are Siamese twins and you share a leg. You are walking down the street and decide to turn left, but your brother doesn't know it and keeps going straight. That should give you a basic idea of the principles involved. |
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My mostly stock F45 does not have the bobbing effect but when I tried HBFP blades, the head speed went up, handling improved, flight times dropped, and significant bobbing came with it. But I always thought the sliding effect was simply a combination of slow head speed and momentum? regards . . . g |
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Australia, QLD, Brisbane
Joined Aug 2012
451 Posts
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If I understand then, Balr14, the problems are rather those of scale, and may have no solution short of FBL?
Understandable, as - after all - the F45 was designed as a 'toy', and easy intro to the world of FP: and not really for the heavy modding we're carrying out on this thread. Reminds me of my valiant efforts to improve the F39 with the addition of a tail rotor - a good try, but simply wasn't going to get me where I wanted to go. Still, within its job description, feel the F45 has to be the best value for money out there. |
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Australia, QLD, Brisbane
Joined Aug 2012
451 Posts
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Gordonzo -
See you're online! In answer to your earlier question, the 30g nose weight is to ensure I can get the heli nose DOWN in the fairly high prevailing winds in my area. Sadly, some months ago had to watch an F45 drift out of sight (despite everything I could do) in a strong gust/ updraft. Hasn't happened since. Regards John. PS - I remember your own first open field crash - my experience was the reverse. I guess these helis do vary a lot (as we've noted). |
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The Netherlands, UT, Nieuwegein
Joined Sep 2012
78 Posts
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Think of it like this. If you move the swash plate 9 degrees and it move the flybar 9 degrees, this is what creates the pictch on the proper place to cause you heli to move. The way it is now, you have pushed the flybar off it's desired plain which is 90 degrees to the main shaft caused by centrifical force. With only the weight, the flybar wants to return to that centre point at 90 degree as fast as possible. Paddles help to keep the flybar in the new plain you have moved it to which gives you the reaction you desire. A good example is a flybar 450 heli. It has paddles and this reaction is very sharp. I know it has a 90 degree flybar and the F45 is 45 degree, but the main difference is the mechanical advantage the the range of movement the 90 degree exerts over the 45 degree flybar. If you have both, move the flybar by hand and what what it does. As I said, I have only have my F45 out twice due to bad weather, but at 80% ELV/ALI settings, it is very close to the response as my 450 for normal flying. At full power, of course, the 450 will change drastically. I have no more sliding effect. |
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Australia, QLD, Brisbane
Joined Aug 2012
451 Posts
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An awful lot to think about in your post, BThirsk!
But thanks to your picture of the modded F45 flybar, decided to put weights on my Trex 450 paddles (it didn't come with any). Reduced the heli from a real challenge to a vaguely cantankerous F45 (in normal mode). Getting there! |
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It gets hard to move from the 4 flybarless CP helis to flybar. The response and reaction on the flybarless is instant and it goes where you point it. That has been my issue with the F45. I needed it to have similar response the the CP helis or quit flying it like I did with the DH9116 which I gave away. |
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Australia, QLD, Brisbane
Joined Aug 2012
451 Posts
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Original quote BThirsk -
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However, when the dust settles a bit - and when (and if) I get reasonably competent with this CP, what next? I really like the 450 size. Can see it a long way off, and it does already seem pretty immune to the local wind. The choice would seem to be between the Blade 450X, and the Align 450 plus DFC. I'm told the best would be the Align with the BeastX - but obviously an expensive road to travel. Any input appreciated! PS - Only crash so far has been as a result of a feathering shaft bolt coming adrift (no thread locker). Even Align RTF can goof! (or really, the motto is - check EVERYTHING). $30 repairs, F45 would have laughed at the 4' drop! |
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