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Old Oct 24, 2011, 07:46 AM
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Originally Posted by jsxx View Post
Hi . Will it be safe to run 7x9g htx900 servos from 3amp bec ? Or do i need something stronger?
You talking about bec incorporated into the esc?
the 9g hxt servos are known for consuming quite a bit of current so I wouldn't recommend using a esc built in bec to power them. not even a 3amp one. You wouldn't want to risk overloading it.

I personally wouls use somethine like this
http://www.hobbyking.com/hobbyking/s...dProduct=16663
at least a 5a one
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Old Oct 24, 2011, 08:12 AM
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Originally Posted by airheli1201 View Post
Hi Guys.

I have a question about the fat shark goggles. My friend has a pre 2010 fat shark rv922 goggles for sale which I am interested. I am aware that there is an updated 2010 version which fixes some problems on the old model. Is the old model good choice for someone starting like me and will there be many problems with this old model?
If you want them as goggles only then there should be no problem at all. You will probably want a separate RX as the one in the goggles isn't very sensitive. Other than that, the FatSharks are great.

-Alex
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Old Oct 24, 2011, 08:15 AM
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Originally Posted by khaled_abobakr View Post
Hi ..

Congratulations on the successful maiden flights ...

I flew my Bixler this morning .. with a CG 7.35-7.4 mm from LE.. and this has made a huge difference in the stability and control of the plane .. now I can glide hands free without diving ... and it is also more stable in turns .. I think I need to practice more before I put the FPV gear one ..

I wonder where are your CGs , FPV guys .. Could you please share CG locations ??

I don't know but it seems the heavy FPV Bixler like a rearward CG (7.35-7.4 mm from LE) than a forward CG .. (6mm from LE) it did make a lot of difference in my case

Here are some photos of my ugly heavy FPV Bixler ... that was the result of undoing a lot of mods ...
The CG mark in the photos should be 7.35 mm not 7.5 ..

Khaled
Khaled - You must be an engineer. You are making one of the most common mistakes: overthinking it. If it flies well LOS, it will do fine FPV. Just fly it. Get used to it and tweak it as you go. Adding weight to the nose makes the plane more stable, but speeds it up.

-Alex
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Old Oct 24, 2011, 08:17 AM
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Originally Posted by jsxx View Post
Hi . Will it be safe to run 7x9g htx900 servos from 3amp bec ? Or do i need something stronger?
You will probably be ok since all 7 servos won't be strained at the same time. HXTs can pull around 500mA, so your BEC is designed to run 6 at full load continuously. However it never hurts to have some extra safety margin and go for a 5 Amp UBEC.

-Alex
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Old Oct 24, 2011, 08:19 AM
There's magic in those wings !
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Originally Posted by IBCrazy View Post
Khaled - You must be an engineer. You are making one of the most common mistakes: overthinking it. If it flies well LOS, it will do fine FPV. Just fly it. Get used to it and tweak it as you go. Adding weight to the nose makes the plane more stable, but speeds it up.

-Alex
Hehehe.. .. yes I'm .. and I meant 7.2 and 7.4 cm from LE... my mistake .. too ..

I'll report my real FPV flights as soon as I have some

Thanks a lot

Khaled
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Old Oct 24, 2011, 10:42 AM
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Originally Posted by IBCrazy View Post
Khaled - You must be an engineer. You are making one of the most common mistakes: overthinking it. If it flies well LOS, it will do fine FPV. Just fly it. Get used to it and tweak it as you go. Adding weight to the nose makes the plane more stable, but speeds it up.

-Alex
I agree with Alex here I was the same way - tried to plan every detail and such. You can certainly have a plan - and it sounds like you do. I had one as well - but my first flight still had some surprises. I've recovered, and I'm always learning from each flight.
I have my CG set slightly forward of the stock EZ* recommendation. The result is exactly as Alex says - she is more stable, but she comes in for a landing noticeably quicker.
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Old Oct 24, 2011, 10:45 AM
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can I ask a newbies quetion here? I have been relying on mah to judge my remaining battery. The figure does not always make sense . I may have used 1450mah on my screen (Eagle tree osd ,etc) and find on charging it is taking 1600 or more - risky!
Should I be using the battery voltage indication rather? I think I can set this up for main battery on the eagle tree ?What voltage is safe for a 3S,minimum? Thanks for any advice, foufly.
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Old Oct 24, 2011, 10:49 AM
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The current measurements are an educated guess, really. I would not count on them for anything more than a reference. The reason is that battery efficiency plays a huge part in it. If I discharge a Lipo at 5C I will get close to the rated mAh of the battery. If I discharge it at 15C I lose 10-15% capacity. At 20-25C that drops even more.

-Alex
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Old Oct 24, 2011, 11:00 AM
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So I've got a question for anyone with a CEOSD. I just got a CEOSD v1.5 for my birthday and will be installing it later this week. I think I've mostly figured out how to hook it up, though it will take a lot of soldering to build a new wiring harness for it, switching over from my current composite video cable hookup to a servo connector based hookup. The one thing I haven't figured out though, is the connection from the OSD to my RC receiver (Corona RP6D1). The OSD has a dedicated connector and provided servo wire to connect to a spare channel on your receiver to turn the screen info on and off.

Two questions: (1) Since channels on my receiver are powered, will it be a problem with the receiver sending power to the OSD? Do I need to cut any wires (I've seen some mentions of that), or will it be fine just hooking it up with the supplied wire without modifying it? (2) I have a cheap Parkzone 72mhz radio which says it's 5-channels but when I looked at the PPM output through the trainer port on my computer it appears to actually be 6-channels. 1-4 are taken up by RC control, but channel 5 is a two-position switch which alternates between 0% and 100% PPM output, and channel 6 is a push button that is normally at 0% but when pressed goes to 100% output for as long as the button is pressed. Which one of these would be best to use for the OSD control channel?
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Old Oct 24, 2011, 01:34 PM
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Thanks Alex ; So the voltage indication is the best?
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Old Oct 24, 2011, 02:16 PM
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Originally Posted by khaled_abobakr View Post
Hehehe.. .. yes I'm .. and I meant 7.2 and 7.4 cm from LE... my mistake .. too ..

I'll report my real FPV flights as soon as I have some
You're talking about two millimeters there... probably not gonna matter at all. When I first started doing this, I thought I should be able to use specific stuff and set up a certain way and have a well-defined operating envelope - but it doesn't work like that, there is no formula. You just need to fly and fly and fly some more, and figure out things as you go along. If you don't like the way the airplane flies and you think a shift in the CG will make an improvement, make a shift and test it - there is no way to calculate the perfect anything in this hobby - you just tweak and test. Every flight is a test - you'll never get it perfect.
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Old Oct 24, 2011, 02:27 PM
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Is this a go, or no-go: 5,8 mhz.. 500mw, or just another microwave?

Ebay-link
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Old Oct 24, 2011, 04:18 PM
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Originally Posted by foufly View Post
Thanks Alex ; So the voltage indication is the best?
I display both for reference but I really watch the volts. I have an alarm set on both. Different batteries have different capacities regardless of the advertised capacity. Even more so when they get older. I try to get back by 11.3 with my 3S 2200s to give me a good margin. The milliamps at that point can varying quite a bit depending on how much throttle I was using. Windy days take the voltage down a lot faster with less milliamps expended, just like IBCrazy said.

Steve
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Old Oct 24, 2011, 05:17 PM
There's magic in those wings !
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Originally Posted by jasmine2501 View Post
You're talking about two millimeters there... probably not gonna matter at all. When I first started doing this, I thought I should be able to use specific stuff and set up a certain way and have a well-defined operating envelope - but it doesn't work like that, there is no formula. You just need to fly and fly and fly some more, and figure out things as you go along. If you don't like the way the airplane flies and you think a shift in the CG will make an improvement, make a shift and test it - there is no way to calculate the perfect anything in this hobby - you just tweak and test. Every flight is a test - you'll never get it perfect.

Hi Jasmine

sorry I wan't clear enough ..

The improvement in flight was clear when I moved the CG from 60 mm to 70.35 mm from LE...

Something I don't like about Inrunners is that they are loud .. and give false impression of too much throttle is being used

Khaled
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Old Oct 24, 2011, 06:21 PM
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Originally Posted by khaled_abobakr View Post
Hi Jasmine

sorry I wan't clear enough ..

The improvement in flight was clear when I moved the CG from 60 mm to 70.35 mm from LE...
That isn't what I was pointing out. What I was pointing out is that you seem to think 350 microns is worth mentioning. Don't think about it so hard - use the TLAR method. There probably is a 'perfect' spot for CG, but it depends on lots of things, such as your flying style, your power setup, your weather, and so on. So it's much easier to start with a good "ballpark" recommendation and then just fly the thing and tweak and fly again until you get what you're looking for. It is hard for us to know what you're looking for, in terms of exact feel, so it's hard for us to advise you on specific details like CG measurements. We can give a ballpark number but there's no such thing as being able to say "set it there and it will be perfect"


TLAR = That Looks About Right

It's probably not your motor that is loud unless you're running a gear box - the noise is from the tips of the propeller going super sonic. If you can run a larger propeller at slower RPM, you can eliminate this noise.
http://en.wikipedia.org/wiki/Lockheed_YO-3
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