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HomeAircraftHelicopterHelicopter Main Discussion › How much of a performance improvement does flybarless setup give you?
10-15-2010 11:06 PM  8 years agoPost 21
McKrackin

rrProfessor

Lucasville,Ohio

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My heli is more powerful(noticeably)and more fun since dropping the flybar.

That's all I got to say 'bout that

I literally never use the word literally right.

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10-15-2010 11:08 PM  8 years agoPost 22
Terrabit

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Seattle, WA - USA

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Careful 1086, you'll get the rolling eyes too!

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10-15-2010 11:12 PM  8 years agoPost 23
DougsRC

rrProfessor

Mass.

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Misinformation ticks me off. And there is no shortage of it. I'll go back to cracking jokes because that is more fun ... for me anyway.
I agree Terrabit ! I don't like misinformation either ! but there are very few absolute truth's in this hobby-- its mostly personal opinion-- in my opinion Fly on-- FB or FBL

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10-15-2010 11:19 PM  8 years agoPost 24
Terrabit

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Seattle, WA - USA

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Thank you Doug!

Rolling eyes are kinda like a finger wag. Not in a Sheffler one ot two fingers, or a South Park "Finger Bang" sense. More like a "oh no you di'nt" sense (notice the missing "d". Like Judge Judy. It's the emoticon equivalent of being shushed. I have been shushed! Shushed like a twelve year old popping bubles in a movie theater. Okay so maybe I was acting like a twelve year old and, maybe I deserved to be shushed. Still, no one would deny that motorcycles don't have doors. And I invite you to fact check that.

The prosecution rests.

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10-15-2010 11:26 PM  8 years agoPost 25
DougsRC

rrProfessor

Mass.

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Still, no one would deny that motorcycles don't have doors.

The prosecution rests.
LoL ! Good stuff man ! May your weekend be overrun with excellent flying ! Peace.

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10-15-2010 11:40 PM  8 years agoPost 26
jones007

rrApprentice

Monterey, CA - USA

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Control latency always leads to increased drag, and eventually instability.
That statement among others you've made seems absurd. Where is your quantitative data to back that up? You made this statement like it's absolute fact...evidence please? You seem to be speaking based on rumors and second or third hand information. That definitely makes for misinformation for people for people who are actually trying to learn on these forums
I've definitely touched some nerves here. I get it - nobody likes to have the things they believe in questioned, but I'm a scientist/engineer, and I find that I'm a skeptic about pretty much everything. My point was never to tell anyone that they were wrong, in particular those that have qualitative evidence from flying both systems. I was really asking for someone to post data so that I would know if all the claims were valid.

With regard to the quotes above:

The increased drag comes about because the system diverges further before the latent controls react and correct the deviation. This requires a larger control input (i.e. a larger cyclic input) since the control input is usually proportional to the deviation, and if the control input is larger, there will be more drag.

You can try this out with some flight-sims. Just run them on an older PC and crank up the graphics until the frame-rate slows down to about 20Hz or so. Then see if you're having to put in larger stick movements to keep the thing flying, and find yourself behind the heli a lot. Most sims won't give you sufficient feedback to see an increase in drag from this, but I don't think anyone will question that a lot of large cyclic inputs bogs a heli.

The instability I think everyone is familiar with on conventional tail gyros. Have you thought about why the gyro/servo makers have been pumping up the control frequency, and reducing the control-loop latency in those systems? In backwards flight the tail is unstable, and latency leads to divergence (tail blowing out). You need both high frequency and very low-latency control systems to manage this correctly.

Deadband is another kicker that causes grief in control systems, but the FBL systems probably have an advantage there due to fewer links, since every link introduces some amount of mechanical slop.

I can provide some references for further reading if people are interested. Controls isn't really my field, but all the guys on my team are control gurus, and I can pick their brains for equations if people want to go that deep into it.

--Kevin

Trex 700N, Trex 600ESP, Trex 500, Trex 450Pro

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10-15-2010 11:44 PM  8 years agoPost 27
McKrackin

rrProfessor

Lucasville,Ohio

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I literally never use the word literally right.

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10-16-2010 12:28 AM  8 years agoPost 28
Terrabit

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Seattle, WA - USA

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The increased drag comes about because the system diverges further before the latent controls react and correct the deviation. This requires a larger control input (i.e. a larger cyclic input) since the control input is usually proportional to the deviation, and if the control input is larger, there will be more drag.
You are talking about such small numbers here that they are for all intents and purposes negligible. Add the latency and the overcorrection multiply it by ten and it probably still would not be noticeable. All of my vbar ships run at 2048Htz frame rates.
The instability I think everyone is familiar with on conventional tail gyros. Have you thought about why the gyro/servo makers have been pumping up the control frequency, and reducing the control-loop latency in those systems? In backwards flight the tail is unstable, and latency leads to divergence (tail blowing out). You need both high frequency and very low-latency control systems to manage this correctly.
vbar has by all accounts the best tail gyro period. I've heard several people who are die hard fb pilots with decades of experience say so after watching or flying a vbar ship. Also, deadband is adjustable in the vbar software.

I like math. I would be interested in whatever equations you can produce. But I would also like to know how they are derived. Careful though, I have a friend who has a double masters from MIT and is a legitimate rocket scientist who just might proof them.

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10-16-2010 12:42 AM  8 years agoPost 29
fenderstrat

rrProfessor

Aston,Pa

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Still, no one would deny that motorcycles don't have doors.
my buddy's harley with sidecar has a door on the sidecar,does that count?

Sorry,I had to

Compass helis Support Team
PerformancePlusRC field rep
Mini Titan/SE
TEAM KBDD

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10-16-2010 01:01 AM  8 years agoPost 30
Terrabit

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Seattle, WA - USA

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Sorry,I had to
Eyerolled TWICE in a single thread!!! Pardon me while I shoot myself. Wait a minute! That ship has sailed. That dog don't hunt no more. I will never be shushed again!!!

The defense rests.

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10-16-2010 01:07 AM  8 years agoPost 31
DougsRC

rrProfessor

Mass.

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Eyerolled TWICE in a single thread!!!
eyerolles only bother those that don't believe that what they are saying is true ! Otherwise -- let the eyes roll ! Why care about the rollin eyes

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10-16-2010 01:15 AM  8 years agoPost 32
jones007

rrApprentice

Monterey, CA - USA

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You are talking about such small numbers here that they are for all intents and purposes negligible. Add the latency and the overcorrection multiply it by ten and it probably still would not be noticeable. All of my vbar ships run at 2048Htz frame rates.
Do you mean 2048 resolution (distinct servo positions, 11-bit)? The frame-rate on most systems from the hand-set to the Rx is only about 45-50Hz, but between the sensor and the servos might be up around 300 to 400Hz.

The deadband I was talking about isn't the deadband that you set in software. That's really a virtual deadband to keep the system from responding to small, unintentional stick inputs when the stick is centered. The deadband that is critical to control systems is the sum of the servo deadband (incidentally usually considerably larger than the 2048 resolution would suggest due to the use of an analog pot in the servos)and all of the mechanical slop in the system between the servo and the control surface. If you've ever tried to crank up the gain on a tail gyro with a junk servo and/or sloppy or sticky control linkage, you'll know all about this. The more slop you have, the lower the gain has to be to avoid limit cycle oscillations (LCO) or tail-wag as we commonly call it.

I just talked to my colleague in controls, and he indicated that there are some nice online instructional tools for PID controllers that will let you enter things like a time-relay between the sensor and actuator to see how it affects stability. I'll try to find one and post it.

You may be right, we might be talking about such small quantities that they are insignificant compared to the loss in drag from throwing out the flybar, but in my line of work, we can't just assume things like that, we have to prove it. I thought for sure that there would be other heli-enthusiasts that would be interested in having some hard numbers rather than just a gut feeling.

--Kevin

Trex 700N, Trex 600ESP, Trex 500, Trex 450Pro

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10-16-2010 01:22 AM  8 years agoPost 33
McKrackin

rrProfessor

Lucasville,Ohio

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Don't need hard numbers.
Flew the heli in the a.m. with a flybar.Fun and fast.
Flew the same heli in the p.m. w/o a flybar.More fun and faster.

I literally never use the word literally right.

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10-16-2010 02:33 AM  8 years agoPost 34
Terrabit

rrElite Veteran

Seattle, WA - USA

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eyerolles only bother those that don't believe that what they are saying is true ! Otherwise -- let the eyes roll ! Why care about the rollin eyes
"Blessed are the cheese makers? What's so bloody special about the cheese makers?"

"It's not meant to be taken literally, it refers to all those manufacturers of dairy products."

Monte Python - Life of Brian

Work with me people!
Do you mean 2048 resolution (distinct servo positions, 11-bit)? The frame-rate on most systems from the hand-set to the Rx is only about 45-50Hz, but between the sensor and the servos might be up around 300 to 400Hz.
Yes, yes, yes. You are correct. My bad. So shoot me!
I just talked to my colleague in controls, and he indicated that there are some nice online instructional tools for PID controllers that will let you enter things like a time-relay between the sensor and actuator to see how it affects stability. I'll try to find one and post it.

You may be right, we might be talking about such small quantities that they are insignificant compared to the loss in drag from throwing out the flybar, but in my line of work, we can't just assume things like that, we have to prove it. I thought for sure that there would be other heli-enthusiasts that would be interested in having some hard numbers rather than just a gut feeling.
Please post the data when you've completed the experiment. I should be very interested in those parts of your findings which it prove my gut feeling.

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10-16-2010 02:47 AM  8 years agoPost 35
Terrabit

rrElite Veteran

Seattle, WA - USA

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Oh, and I realize it's 6:45 PM Friday evening but, I'm going to need that report Monday AM, or we may be having another conversation which includes such questions as how crucial are your services to the company's mission.

Capiche?

Ha! I've been there. Anybody else?

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10-16-2010 03:00 AM  8 years agoPost 36
SpinergySpox

rrNovice

Green Bay, WI

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Hey Terrabit, I hate to break it to you, but jones007 is making a much more intelligent argument than you are (and a much more civil one as well).

He’s making arguments based on engineering principles. You? Your argument is essentially “that’s what I’ve noticed about FBL helis”.

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10-16-2010 03:04 AM  8 years agoPost 37
Band1086

rrElite Veteran

Kennewick, Wa. USA

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rather than just a gut feeling.
Not sure why you're referring to it as only that. There have been many people that have testified to the difference. Back when the MA Fury
came out, I had been flying all conventional mixing machines and was pretty happy with them...that was the common tech of the day. But when I flew my Fury the first few times and got used to it(it was very different)I was amazed how much more agile it was than all that I had been flying before. FLB is very similar to that but even more so. It's much more agile and more stable. I've never flown FBL on a nitro as I converted to electric before FBL, however there is a noticeable difference in flight time and temperature of equipment upon return from a flight. I have not logged the numbers as I never considered I might be called on to give hard numbers as testimony. But I was very pleasantly surprised with the differences. I use all 700 sized equipment BTW, so I couldn't speak as to the small ships. I have tried both the VB and the TG. While the 5.0 is very stable the TG seems to show less latency. With the TG it is possible to turn off "trim lock" IE cyclic heading hold to get the feel of the FB without the limitations of the actual FB. I still have a lot of flying to do to get a real feel for the differences between them, however, they are both more agile and stable than a common 3D FB set up...

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10-16-2010 03:05 AM  8 years agoPost 38
McKrackin

rrProfessor

Lucasville,Ohio

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At least he's "noticed" a FBL heli

I literally never use the word literally right.

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10-16-2010 04:03 AM  8 years agoPost 39
Aaron29

rrProfessor

USA

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..

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10-16-2010 04:22 AM  8 years agoPost 40
Terrabit

rrElite Veteran

Seattle, WA - USA

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Hey Terrabit, I hate to break it to you, but jones007 is making a much more intelligent argument than you are (and a much more civil one as well).

He’s making arguments based on engineering principles. You? Your argument is essentially “that’s what I’ve noticed about FBL helis”.
Frankly Scarlet, I don't give a damn!

Pay me and I'll make a better one. Besides, I'm right.

Oh, and I'd probably forgo the Montey Python references if I was actually trying to sell anything. But hey, Montey Python is funny.

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HomeAircraftHelicopterHelicopter Main Discussion › How much of a performance improvement does flybarless setup give you?
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