gyro
GSN Contributor
Guys, I'm horribly sorry. When I was promoting SteveB's excellent post showing how many feet and airplane will travel with slow latency, I accidently deleted this whole thread. I was able to recover the below, which should keep things going for a bit, but again, my fault, I really messed up.
Originally Posted by Steve_B
- Yesterday, 08:49 PM #45
Joe Smith
Originally Posted by 3Daddict
It is not slow, I had a spectrum dx7 before the A9 and the A9 feels more locked in than my spectrum dx7 ever did. However I guess that is what a futaba fan would say. I know a fairly good flyer that flys nothing but futaba at my field who flew one of my airplanes with my A9 and told me that my A9 felt the same as his futaba if not better. not to mention Hitec is a lot cheaper than futaba and just the same quality.
Fortunately, the amount of latency in our systems can be found through tests so we can acutally prove which radios are faster than others.
Take a look at this.
http://rc.runryder.com/helicopter/t172571p1/
As you can see, the Aurora 9 is up there with the slowest radios on the market. I've had the opportunity to put many months on a dx6,dx7, jr12x, aurora 9, 8fg, and the 18mz. I can honestly say that performance alone is the only reason I am still flying futaba.
Also, what information do you have to back up saying that the quality of hitec products is the same as futaba? All of the testing I have done would easily disprove this statement but I won't say you are wrong. I am just wondering where you got your information?
- Yesterday, 08:52 PM #46
3Daddict
I am just messing around also, I have to say I am a fan of futaba and may get one as my next radio in a few years. I just figured since this is the radio wars thread I would stir the pot a little.
- Yesterday, 08:54 PM #47
3Daddict
none, just the feel of the radio. Maybe I came down to harsh on futaba. But I have to say that futaba and hitec both make some of the best radios on the market.
- Yesterday, 08:54 PM #48
Jim Smith
Originally Posted by 3Daddict
I am just messing around also, I have to say I am a fan of futaba and may get one as my next radio in a few years. I just figured since this is the radio wars thread I would stir the pot a little.
ROTFLOL
Score
- Yesterday, 09:00 PM #49
3Daddict
Ok, I will admit that futaba is the best. However I still maintain that the A9 feels more locked in than my old dx7. You win Jim. I bow out of this radio wars.
- Yesterday, 09:07 PM #50
GYRO
My Dx8 has been pretty reliable so far, and in 11ms High Speed mode, is plenty fast for my weak skillz.
- Today, 05:30 AM #51
Manta
LOL Tell you guys a secret,my A9 with the XPS module and nano receivers feels the same as Losi's futaba 8FG ( which I really liked except for hand position on radio) but as far as the "locked in" feeling,same.. specky stuff doesnt "feel" as locked in as the futaba and the A9 with xps.. the hitec module and receivers tho felt goos,but the lag is noticeable for the high alpha stuff. I felt like I was chasing the plane..but this coulda been lack of skills too but it changed when i went to the faster XPS system.
The 8fg I could get used to hand/finger/switch position with a few flights. I call my A9 better because of the touch screen and the rx are 30 bucks..more bang for the buck. and I love my touch screen. But i wouldn't turn an 8fg or higher end futaba down either. just the prices are ridiculous.Team Mascot for Motrolfly
- Today, 06:12 AM #52
3Daddict
I have to disagree about it feeling like you are chasing your plane in high alpha 3d, all I do is 3d and I have never once felt behind my plane. I always feel locked in.
- Today, 07:11 AM #53
Steve_B
This talk about letency misses what is the biggest contributer to latency.. the servo itself! Latency is defined as the time taken between a command and the control surface reaching it's commanded position so you really need to take the servo into consideration.
If you take the latency data linked previously by Jim, the fastest systems (example; Futaba 8FG and 10C, Spektrum DX8 and DX7se, ATX SD-10G) fall in a latency band 10 to 20ms. Compare that to the slowest systems (example; Hitec Aurora 9, JR 9303, the old type Spektrum DX6) are in a band 50+ms
The average difference between the best systems and the worst is about 35-40ms
Now lets look at a servo.. To travel 60 deg under no load here are some typical times (small sample of servos i have experience of):
Savox SH-0257: 90ms
Savox SH-0255: 130ms
Hitec HS-65MG: 130ms
Hitec HS-85MG: 160ms
So taking the best to the worst of these times the difference is 70ms, so the contributed to overall latency caused by the servo is potentially significantly greater than that of the radio. It's perfectly feasable that the guy with the slow Aurora 9 will in fact have better overall responsiveness than the guy with the Futaba 8FG purely because the Hitec flyer has faster servos.
Having said that, lower radio system latency is better and a difference of 35-40ms is quite significant and must be noticable in flight, all other factors (including servos) being the same. Hitec need to get it sorted!a.k.a 'JetPlaneFlyer'
- Today, 07:28 AM #54
teookie
yeah but,
the plane doesn't wait for the servo to get all the way to it's commanded position before it reacts. As soon as the control surface moves 1 or 2 degrees towards it's commanded position the plane will start reacting.
so, time from stick movement to the plane doing something is still largely dependent on TX latency.
what fast servo's do is allow you to change direction really quick and get large deflections very quickly.
- Today, 07:47 AM #55
Manta
Yea hybrid hitec xps man!!! Woot!!
Jim drew needs to quit smooozing that movie guy and his aquatic quests and get his miracle tx to market.
Lol
Team Mascot for Motrolfly
- Today, 09:46 AM #56
Steve_B - Originally Posted by teookie yeah but,
the plane doesn't wait for the servo to get all the way to it's commanded position before it reacts. As soon as the control surface moves 1 or 2 degrees towards it's commanded position the plane will start reacting.
That's true but the plane with the faster servos will always have less lag in it's response to stick input because the surface will move faster compared to the plane with slow servos (all other things being equal). Faster reacting control surfaces means faster reacting airplane so servo speed is part of overall latency, no getting away from it.
In practice i bet it would be impossible to tell the difference between a high latency radio and a slow servo, they would both make the plane feel sluggish, especially so in 3D where we need the servo to move a long way.
Last edited by Steve_B; Today at 09:49 AM.a.k.a 'JetPlaneFlyer'
- Today, 10:26 AM #57
Jim Smith
Originally Posted by Steve_B
That's true but the plane with the faster servos will always have less lag in it's response to stick input because the surface will move faster compared to the plane with slow servos (all other things being equal). Faster reacting control surfaces means faster reacting airplane so servo speed is part of overall latency, no getting away from it.
In practice i bet it would be impossible to tell the difference between a high latency radio and a slow servo, they would both make the plane feel sluggish, especially so in 3D where we need the servo to move a long way.
Built 2 identical planes. Same servos ESC, etc.
1 Flown with A9
1 Flown with 8FG
Lag was noticiable enough that a random spectator could tell which radio was being used. Didn't even need to be using the radio, just observing how the plane reacted in the stunts being flown.
- Today, 11:56 AM #58
3Daddict
Question for you Jim. I got to thinking about it and I only fly 57'' and under planes which are quick responding as it is. Perhaps the lag is not noticeable to me because of this, and maybe it is more noticeable on a larger plane. What do you think? - Today, 12:18 PM #59
hone1er
Originally Posted by Jim Smith
Built 2 identical planes. Same servos ESC, etc.
1 Flown with A9
1 Flown with 8FG
Lag was noticiable enough that a random spectator could tell which radio was being used. Didn't even need to be using the radio, just observing how the plane reacted in the stunts being flown.
That's one skilled spectator. They must watch a lot of flights
The A9 has been working great for me but i would like to try a Futaba radio someday as well just to see if i really notice the difference.
Last edited by hone1er; Today at 12:22 PM.We're all here for 3D
- Today, 12:54 PM #60
Steve_B - Originally Posted by hone1er ... i would like to try a Futaba radio someday as well just to see if i really notice the difference.
Doesn't have to be Futaba. The spektrom DX7se or DX8 in 11ms mode are pretty much as fast as Futaba (a bit faster than some Futaba models marginally slower than others). To be honest though I bet there is some considerable element of subjectivity in what 'feels' faster especially when we are talking about differences of a hundredth of a second or less.
Bear in mind that the average human reaction time between an event and the finger reacting is 215ms: http://www.humanbenchmark.com/tests/...time/stats.php , and that's when we are concentrating 100% and expecting the 'event' to occur.
a.k.a 'JetPlaneFlyer'
- Today, 01:04 PM #61
Jim Smith
Bear in mind that the average human reaction time between an event and the finger reacting is 215ms.
But Average Humans don't fly like this
- Today, 01:23 PM #62
Steve_B
- Originally Posted by Jim Smith
But Average Humans don't fly like this
Indeed not but I'm not sure how much of that outstanding ability is due to reaction time. Seems to me that most inputs during acrobatics are planned in advance, even if only a fraction of a second in advance. It's maybe more about predicting when the plane will do and planning ahead than it is to reacting to events.. No?
Having said that having super fast reactions must help a bit; so how does Joe score on the human reaction test: http://www.humanbenchmark.com/tests/...time/index.php
Indeed not but I'm not sure how much of that outstanding ability is due to reaction time. Seems to me that most inputs during acrobatics are planned in advance, even if only a fraction of a second in advance. It's maybe more about predicting when the plane will do and planning ahead than it is to reacting to events.. No?
Having said that having super fast reactions must help a bit; so how does Joe score on the human reaction test: http://www.humanbenchmark.com/tests/...time/index.php
Last edited by Steve_B; Today at 01:24 PM.
a.k.a 'JetPlaneFlyer'
- Today, 01:32 PM #63
Steve_B
FWIW my I cant get human reaction score much below 250 That might explain why my 3D sucksa.k.a 'JetPlaneFlyer'
- Today, 01:34 PM #64
Joe Smith
Originally Posted by Steve_B
FWIW my I cant get human reaction score much below 250 That might explain why my 3D sucks
I just tried it too. All I will say is that you can't use 250 as an excuse.
That might explain why my 3D sucksI just tried it too. All I will say is that you can't use 250 as an excuse.
- Originally Posted by Steve_B Indeed not but I'm not sure how much of that outstanding ability is due to reaction time. Seems to me that most inputs during acrobatics are planned in advance, even if only a fraction of a second in advance. It's maybe more about predicting when the plane will do and planning ahead than it is to reacting to events.. No?
Having said that having super fast reactions must help a bit; so how does Joe score on the human reaction test: http://www.humanbenchmark.com/tests/...time/index.php
I cut a lot of it out of the video, but left some in. Reaction is when your flying your plane in a direction and all of a sudden a plane is in your predetermined aerobatic maneuver. Reaction time keeps you from building a new plane. Or when your torque rolling a few inches off the deck and a gust of wind hits. People think that once you learn the stirr correctly, reaction time isn't necessary. Try a rolling loop flying both directions. Does both of yours look the same. Only if you are controlling the plane by reacting to minut variations will they both be the same.
I calculated it once. But with the A9 the plane would fly 6' before reacting to stick input, versa 1.5 feet for the 8fg. Have you seen a heartattack maneuver. 6' would mean a rebuild.
- Today, 02:20 PM #66
Steve_B
Jim,
how far the plane would fly between the stick moving and the servo receiving a signal to move is an interesting point and maybe helps put some reality into pretty much meaningless talk of a few ms here and there.
Of course it totally depends on how fast the plane is flying! 3D model aren't really so fast so what about if we take 30mph as an average speed half way between walking speed harrier and WOT high speed manoeuvres?
30mph is 44ft per second (5280/60^2)
Based on the data shown in the linked thread:
The Hitec Aurora 9 being about the slowest of the current systems is 55ms latency. Thats 0.055 seconds so the plane travels 2.42ft
The Airtronics SD-10G is the fastest at 10.3ms. that's 0.01 seconds so the plane travels 0.44ft or 5.3"
So I calculate the difference between the fastest and the slowest radios at 30mph flying speed, everything else being exactly equal, to be near enough 2ft (24").. That could very easily be enough to make the difference between a crash and a near miss. It's hard to see how a 2.42ft departure from the desired flight path would not be noticeable
The Futaba 8FG (in high speed mode) plane would travel 0.62ft (7.4") and the Spektrum DX8 (in 11ms mode) plane would travel 0.84ft (10.1").. so not much in it at the faster end of the scale.Last edited by Steve_B; Today at 02:25 PM.a.k.a 'JetPlaneFlyer'
- Today, 08:33 PM #67
Jim Smith
Originally Posted by Steve_B
Jim,
how far the plane would fly between the stick moving and the servo receiving a signal to move is an interesting point and maybe helps put some reality into pretty much meaningless talk of a few ms here and there.
Of course it totally depends on how fast the plane is flying! 3D model aren't really so fast so what about if we take 30mph as an average speed half way between walking speed harrier and WOT high speed manoeuvres?
30mph is 44ft per second (5280/60^2)
Based on the data shown in the linked thread:
The Hitec Aurora 9 being about the slowest of the current systems is 55ms latency. Thats 0.055 seconds so the plane travels 2.42ft
The Airtronics SD-10G is the fastest at 10.3ms. that's 0.01 seconds so the plane travels 0.44ft or 5.3"
So I calculate the difference between the fastest and the slowest radios at 30mph flying speed, everything else being exactly equal, to be near enough 2ft (24").. That could very easily be enough to make the difference between a crash and a near miss. It's hard to see how a 2.42ft departure from the desired flight path would not be noticeable
The Futaba 8FG (in high speed mode) plane would travel 0.62ft (7.4") and the Spektrum DX8 (in 11ms mode) plane would travel 0.84ft (10.1").. so not much in it at the faster end of the scale.
I really hope everyone reads your post carefully. Its exactly what we are discussing. Latency is = to distance traveled.
2.4' versus .62' is a bunch when your flying 6" about the ground. I really hope people understand that latency is a real number. Not imaginary at all.
- Today, 08:43 PM #68
GYRO
excellent posts and information Jim and Steve. That is exactly the way to sort through this type of stuff, plain math and good explanation! I liked it so much I made it an article!
