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Old Feb 01, 2013, 10:46 AM
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Canada, QC, Châteauguay
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I have a question about CG.

With my Radian Pros, I used to leave the wings off and support fuselage with all standard, non-FPV stuff in place and then support the plane by the wing spar -- this would result in a perfectly level plane (which was simpler to just verify visually on the Radian Pro). On that plane, it seemed that the CG was right at the spar so I could add stuff and tweak the CG in real time.

Here's my questions about the Penguin:

1) Since the CG is intended to be 8.5cm back from the leading edge at the root of the wing, picking up the plane, without wings, at that point (with one finger per side) should yield a balanced plane, right?

2) with the wheels sitting on the ground, the plane is actually pitched up a little, right? So picking the plane up as indicated above would result in a slight nose-down if the CG was correct(?)

3) If the above is correct, then what surface on the plane can we use to verify as flight-level? Is the mounting surface in the bottom of the cockpit intended to be level in level flight? Beyond getting the CG right, I am also asking if this is a good spot for the Eagle Tree Guardian Stabilizer.

Thanks!

Scott
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Old Feb 01, 2013, 01:06 PM
FunkMaster
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United States, OH, Mason
Joined Jan 2011
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Scott,

Using the method described in #1 assumes that the center of mass of the wing is exactly at the same point as the CG of the entire airframe. This most likely isn't true although it's probably not far enough off to make a huge difference.

Regarding #3, your pitch for level flight is going to depend on the weight of your plane fully loaded, how far off the center of lift is from the CG and the speed the plane is flying. With my Penguin at full weight, I find that I need to set the ET guardian level with the nose pitched up (similar to the pitch up you get when resting on the wheels).

I think you're going to need to do some trial and error to find a attitude that results in a good trim for the speed you normally fly.

Probably wasn't what you were hoping to hear

Kent
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Old Feb 01, 2013, 01:22 PM
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Canada, QC, Châteauguay
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Thanks, Kent!

I guess leaving the wings out was oversimplifying things to a degree.

Would you say lifting the plane at the position stated above WITH the wings on is a better way to get in the ballpark.

You are also saying the the forward velocity is going to dictate what is considered level flight, so a moderate cruise velocity should probably be the benchmrk, then(?)

Finally, do you tweak the pitch on your Guardian manually or just mount it on an intended-to-be-level surface and then set that as "level" via the software/on-screen menu?

Scott
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Old Feb 01, 2013, 01:47 PM
FunkMaster
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United States, OH, Mason
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Originally Posted by s_linste View Post
Thanks, Kent!

I guess leaving the wings out was oversimplifying things to a degree.

Would you say lifting the plane at the position stated above WITH the wings on is a better way to get in the ballpark.

You are also saying the the forward velocity is going to dictate what is considered level flight, so a moderate cruise velocity should probably be the benchmrk, then(?)

Finally, do you tweak the pitch on your Guardian manually or just mount it on an intended-to-be-level surface and then set that as "level" via the software/on-screen menu?

Scott
I would say it's definitely better to do it with thet wings on. The angle of attack of the wing (and rest of the fuselage) will generally be lower at high speed and higher at low speeds asuming you're not climbing or diving. This is one reason the guardian instructions have you trim the plane first without being active and then turn on the stabilization. You might want to make some LOS passes lower to the ground and get an idea of the pitch the plane has during level flight.

I mounted my guardian in a secure place and didn't worry about it being exactly level. It is somewhat close. I made sure it wouldn't shift or move though. I then set the level using the OSD screen and it works great. When I set level using the screens, is when I worry about the wings being level and the nose being at the right attitude.

I would say don't over-think it though. In my experience, the guardian adapts well and seems to be fairly forgiving.

Kent
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Old Feb 01, 2013, 02:36 PM
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Copperopolis, CA
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Speaking of CG...

I'm getting ready to maiden my Penguin. Is the consensus that the published CG of 85mm/3.35" is good. Seems a little aft to me, but the proof is in the flying.

Thanks.


Jack
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Old Feb 01, 2013, 03:27 PM
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United States, Mt, Great Falls
Joined May 2011
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Originally Posted by McCleary.11 View Post
Pull out the esc and check for loose bullet connectons. I would cut off the heat shrink on those wires so you can inspect them for any bad solder joints. Easy to do and just add more heat shrink.

I would also say to increase the ESC timing, but since you had a successful flight, I doubt that's the case.
today lol
yep loose wires to bad the wind is crazy today i had 15000mah to burn thanx for the help
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Old Feb 01, 2013, 06:24 PM
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Cayman Islands, Grand Cayman, George Town
Joined Apr 2006
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Hey guys, just finished reading through this thread over the span of a few days, anyway lots of good info. I have had my penguin since the early part of January and been flying LOS for the most part with gp3 attached. Just got my fpv gear early this week and have finished the install today. My son and I did a small range check with everything turned on and Im getting good control out at 60-75ft (radio powered down) and the video on my goggles have no signs of interference, yet!

Sunday will be my first flight fpv (Im an fpv virgin lol) after of course everything checks out on the ground and a LOS flight with someone looking through the goggles.

Just want to send a big thanks to Dave at RMRC who answered all my questions and pointed me in the right direction with my purchases and to Tim for a great first experience from RMRC..shipping to here literally took 3 days by USPS.
Thanks to the guys on here for the great read so far, need to start the other penguin thread now.
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Old Feb 02, 2013, 03:08 AM
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United States, CA, Sacramento
Joined Feb 2012
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Originally Posted by kman Raptor View Post
Hey guys, just finished reading through this thread over the span of a few days, anyway lots of good info. I have had my penguin since the early part of January and been flying LOS for the most part with gp3 attached. Just got my fpv gear early this week and have finished the install today. My son and I did a small range check with everything turned on and Im getting good control out at 60-75ft (radio powered down) and the video on my goggles have no signs of interference, yet!

Sunday will be my first flight fpv (Im an fpv virgin lol) after of course everything checks out on the ground and a LOS flight with someone looking through the goggles.

Just want to send a big thanks to Dave at RMRC who answered all my questions and pointed me in the right direction with my purchases and to Tim for a great first experience from RMRC..shipping to here literally took 3 days by USPS.
Thanks to the guys on here for the great read so far, need to start the other penguin thread now.
Great to hear!

Your going to love FPV, guaranteed addiction!

Little advice for your first flight that helps a lot.

-Make sure the plane flies nice and level LOS before looking into goggles or monitor.

-Have a spotter with you that is watching the plane.

-Get to a good altitude before throwing goggles on or looking into monitor. This will allow you extra time to correct something if there is a problem.

-Don't fly on a windy day. (It will be tempting, but don't do it).

Last but not least, have fun and welcome to a whole new part of your life!


Cheers,
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Old Feb 02, 2013, 05:02 AM
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United States, OH, Powell
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I would suggest not even looking at a screen until the second flight. Best to record the first and review it. Even if it is only an out and back as far as you can see it. Then land and look at the recording if it is good have fun!
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Old Feb 02, 2013, 07:17 AM
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Joined Sep 2008
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a little off topic question...as my penguin is still on its way..
i have been looking for dragonlink uhf everywhere. but its out of stock on every site.
can i order it directly from dragonlink website, it seems that they are taking orders and claims that it will b shipped in 2 3 days. are they selling it within the US?
if any one has bought from them directly, please let me know asap.

cheers
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Old Feb 02, 2013, 07:57 AM
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Canada, QC, Châteauguay
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Originally Posted by asif222 View Post
a little off topic question...as my penguin is still on its way..
i have been looking for dragonlink uhf everywhere. but its out of stock on every site.
can i order it directly from dragonlink website, it seems that they are taking orders and claims that it will b shipped in 2 3 days. are they selling it within the US?
if any one has bought from them directly, please let me know asap.

cheers
+1 I also would like to know if dealing directly with the company is a good move.
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Old Feb 02, 2013, 07:59 AM
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Cayman Islands, Grand Cayman, George Town
Joined Apr 2006
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Originally Posted by swartzracing View Post
Great to hear!

Your going to love FPV, guaranteed addiction!

Little advice for your first flight that helps a lot.

-Make sure the plane flies nice and level LOS before looking into goggles or monitor.

-Have a spotter with you that is watching the plane.

-Get to a good altitude before throwing goggles on or looking into monitor. This will allow you extra time to correct something if there is a problem.

-Don't fly on a windy day. (It will be tempting, but don't do it).

Last but not least, have fun and welcome to a whole new part of your life!


Cheers,
Quote:
Originally Posted by fpvbasher View Post
I would suggest not even looking at a screen until the second flight. Best to record the first and review it. Even if it is only an out and back as far as you can see it. Then land and look at the recording if it is good have fun!
Thanks guys all good info go on.

On another note. I'm finding that I like the cg on this plane a little forward of the manufactures suggestions.
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Old Feb 02, 2013, 09:16 AM
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United States, OH, Delaware
Joined Mar 2006
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Originally Posted by kman Raptor View Post
Thanks guys all good info go on.

On another note. I'm finding that I like the cg on this plane a little forward of the manufactures suggestions.
I am very jealous of your flying location. Make sure to post some videos!
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Old Feb 02, 2013, 09:18 AM
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United States, OH, Delaware
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Originally Posted by s_linste View Post
+1 I also would like to know if dealing directly with the company is a good move.
RMRC has a new shipment on the way if you don't want to deal with DL directly. Not sure on the exact date they will arrive, but should be next week.
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Old Feb 02, 2013, 10:45 AM
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Cayman Islands, Grand Cayman, George Town
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Originally Posted by McCleary.11 View Post
I am very jealous of your flying location. Make sure to post some videos!
As a vacation destination, yes, many would be but you do not want to be an avid modeler here. Only one hobby shop here and the guy never has what you need and prices are somewhat questionable..its cheaper to order online but then you have to wait and I hate that.

Ill make sure to post up videos as I get into the rhythm of things, there are a few sites that I would love to get some footage of.
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