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Old Mar 15, 2010, 09:41 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Joe,

Send me your tip panels and I'll send them back with honest-to-goodness working winglets... They even have a guarantee attached... (If you like them... they're yours. If you don't like them... they're still yours... )

Jack
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Old Mar 15, 2010, 10:00 PM
RIP MC
fnnwizard's Avatar
United States, CA, Midway City
Joined Dec 2003
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Of course flying smoothly helps. But in the dip zoom, there's not much time to operate the sticks smoothly. For me the dip is like one motion, down then right back up less than .5 sec.

One can argue... that a faster servo would allow a slower movement of the sticks, which may result in moving the sticks more smoothly.

I have starting using the JR Z3650, but it's no secret. Many F3J guys have been using them for a few yers now... I just started to realized the difference .
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Old Mar 15, 2010, 10:52 PM
F3B and F3K
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United States, TX, Dallas
Joined Mar 2009
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If I may add something to the servospeed:

I normally use the smallest servo horns possible on the elevator in my F3B planes -thereby I reduce slop, increase accuracy and deliberately reduce the angular speed of the elevator.

Nevertheless I had never the impression I am missing something in the dip-zoom phase of the launch. My best launch height in a competition was 340m (Kirchheim, very windy). It is likely that the top guys launched higher that day, but I don't assume it was due to servo speed.

The overall response of the airplane on elevator input not solely depends on the servo speed, but more importantly on the settings of the plane and its dynamics (e.g. how its system response looks like).

I can make my planes react violently on elevator using an agressive set up, but in my experience a harmonic launch is better suited to most of the current designs.

But back to the Tragi, we have been hijacking Marc's thread long enough.

Reto
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Last edited by RetoF3X; Mar 16, 2010 at 08:59 AM. Reason: typo + system response +figure caption
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Old Mar 15, 2010, 11:22 PM
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United States, CA, San Luis Obispo
Joined Aug 2006
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Perhaps it is a cultural thing between F3J and F3B. The best launches that I have observed and performed have a smooth round out in the bucket. We have very soft elevator settings for this flight phase, in order to avoid scrubbing off speed.

You can get away with a lot in the wind, but all of these techniques will add up in no-wind conditions.

PS - Reto is that a Europhia? I loved mine

PPS - "Oops" is my middle name...
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Old Mar 16, 2010, 08:18 AM
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Jack, when you attended Texas A&M University voluntarily, you get use to being at this end of the questioning.

Reto, hey, this is fun, no building till I get home end of the week. Keep talking!

Marc "Oh Crap" Gellart
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Old Mar 16, 2010, 08:57 AM
F3B and F3K
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Aaron, it is a Evolution V-tail: http://www.jitom.com/pages/news.html

When you have to make ultra-short launches in F3J (<1s), I can understand that the J guys are interested in fast elevator response. I saw Philip Kolb and Tobias Laemmlein doing such stunts and it is amazing how much altitude they get out of a very short launch.

Reto
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Old Mar 16, 2010, 10:51 AM
Challenge is rewarding
djklein21's Avatar
San Diego, CA
Joined Aug 2004
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Quote:
Originally Posted by fnnwizard View Post
Of course flying smoothly helps. But in the dip zoom, there's not much time to operate the sticks smoothly. For me the dip is like one motion, down then right back up less than .5 sec.

One can argue... that a faster servo would allow a slower movement of the sticks, which may result in moving the sticks more smoothly.

I have starting using the JR Z3650, but it's no secret. Many F3J guys have been using them for a few yers now... I just started to realized the difference .
Tuan, Reto is right here. I think the difference in the posts comes from both experience and the use of mono vs. braided line. With braided line, there is very little bucket in comparison. With mono, whether B or J, the bucket is flown. It may seem like one smooth fluid motion (hopefully) but every launch is slightly different, with different conditions, different stretch...and a different angle and depth in the bucket. Killer elevator servos and a really fast transmitter/receiver link only aid in this department.

I for one don't think that fast servos promote jerky maneuvers, but rather help with the pilots timing. In fact, I believe the opposite, slow servos (in the very extreme case) keep you behind you model. I have flown UAVs through data links with considerable lag. There is no way that I could have preformed an F3B/J launch using these data links. I would never attribute a pilot/planes performance to decreased radio latency or faster servos, but they can only help. I will always use the fastest servos possible. I can always use my Tx to slow them down if I need
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Old Mar 16, 2010, 11:46 AM
or F, J, K, or even TD
FLY F3B's Avatar
Joined Jun 2007
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Lets see, how do you techy group guys say it....oh yeah,

+1 for Dave and Reto

The only time you need, absolutely need, super fast servos for the elevator is when you want very tight, crisp pitch changes at a very high airspeed (ie. F3J launch) But, if your thumbs are not up to the task, then all bets are off. I will say too that a fast RF connection, and fast servos will help those less experienced to feel more directly attached to their planes.

Cheers,

Mike
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Old Mar 16, 2010, 12:40 PM
Eggcellent...
tewatson's Avatar
United States, CA, Orange
Joined Oct 2006
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Actually, the proper and approved affirmation is "harumpfh".

Tom

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Old Mar 16, 2010, 12:49 PM
Sink Stinks
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Orange County, CA
Joined Aug 2004
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Quote:
Originally Posted by FLY F3B View Post
fast servos will help those less experienced to feel more directly attached to their planes.
I thought that was what CA was for
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Old Mar 16, 2010, 12:57 PM
RIP MC
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United States, CA, Midway City
Joined Dec 2003
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While we are on response time subject, thought I'd throw this out really quick. Here's the difference in height on an F3B launch at 70M/S with a 10ms radio vs one at say 35ms, which is still considered pretty fast. When you think you need to dip at point A, the 10ms radio will input signal to servo at point B, and the 35ms radio will input at point C.

It translates to a little over 2 meters, which to us normal guys is tiny, but would it matter to a world class pilot? I don't know. Yes, there are a thousand things that can mess the flight up, but if everything was the same, what would th extra 2 meters translate in distance, thermal and speed?

Again, changing nothing else but response time of radio.
Again, just something esle to think about.

I'm sorry Mark for cluttering up your build thread .
Tuan
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Old Mar 16, 2010, 01:39 PM
Sink Stinks
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Orange County, CA
Joined Aug 2004
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Now you are mixing in radio latency with the servo speed discussion. But an interesting look at the situation. So that 25 ms difference in radio latency results in a theoretical difference in launch height of approximately 2 meters. If it is linear, then that is about 0.08 meters per millisecond of difference in latency.

And again, human reaction time averages around 225 ms.

Which makes me wonder how many downwind turns can dance on the head of a pin.
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Old Mar 16, 2010, 01:55 PM
Challenge is rewarding
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San Diego, CA
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Actually he is stating that the plane flies 6 feet in 25ms. So the plane using the faster radio will begin its pullout 6 feet before the slower radio if the pilot had the same command.


Quote:
Originally Posted by Silent-AV8R View Post
Which makes me wonder how many downwind turns can dance on the head of a pin.
best quote of the thread
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Old Mar 16, 2010, 01:58 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Quote>Which makes me wonder how many downwind turns can dance on the head of a pin. <Quote

OK gents... Winter's officially over in 5 days... If we're going to have a down-wind turn discussion, it has to be short...

Jack
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Old Mar 16, 2010, 02:16 PM
RIP MC
fnnwizard's Avatar
United States, CA, Midway City
Joined Dec 2003
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Quote:
Originally Posted by djklein21 View Post
Actually he is stating that the plane flies 6 feet in 25ms. So the plane using the faster radio will begin its pullout 6 feet before the slower radio if the pilot had the same command.
Yeah, that's only with a 25ms difference. Taking a popular tx/module combo today with max latency of 68ms and comparing it to the fastest one, real numbers could be as big a difference as 3.9 meters on F3B launch and 2.2m on F3J launch (at 40m/s).

This does apply to all skill levels and reactions times because it's the same pilot and plane. (Btw, my reaction is in the 280ish today , little earthquake last night got me to stay up).
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