The Importance of CG (Center of Gravity) Class 11
Posted March 26th, 2009 at 08:49 PM by ThursdayBeginnerBlog
Watch this video FIRST. It talks about your CG works, why it so important, and how to make your plane more stable in general.
In this video we are talking more about how to find the CG on your plane and what happens if you move it more forward or backwards.
How to Find the CG for Your Plane
1) It should be on the instructions of your plane. Whatever it says, its safe to go just a wee nose heavy from that! Then for your next flight, move your battery slightly back and see how you like that.
2) Chuck glide it! If you are building a foamie, before you put all the electronics on it, straighten out the control surfaces with tape, put a small weight on the nose, and throw it over the grass! Adjust the weight until you have it doing a nice steady glide! Now you found your CG and put your electronics on from there!
3) Just guess. Make it what you think is a little nose heavy and just be ready to give your plane some up-trim after it takes off. This is fine, just land the plane, move the battery slightly back, reset your trim and repeat. This is what we do most of the time.
4) CG Calculator Page and Canard CG Calculator Page oh and THIS ONE too. These fancy pages only works if you have a very traditional "wing" and "tail". Remember, on all your foamies your nose and body also count as the "wing" so this locater page is not going to be good for you. We never use this page even though its very popular.
5) Benefits of Tail Heavy
Moving your CG farther back will give you more maneuverability like we did with our Wild Hawk and out Su-35 (just scroll down the pages). A gyro is greatly appreciated to help keep the plane steady doing this as the plane always wants to flip up!
Last Week's Question for the Class Was:
Spoilerons work so amazingly well on RC planes for high alpha, so why don't full size fighter jets use spoilerons for high alpha?
I think Inder-Nett gave the best answer. What he basically said is because the full size jets are so heavy, they need more lift than they need stability when they are doing high alpha do to their tremendous weight.
I think this is very true and explains all if not most of the reason why full size jets don't use spoilerons for high alpha.
Today's Questions for the Class:
Next week is our last Thursday Beginner RC Show. Within the next month we will be changing around our video schedules with different shows at different times so we can answer your specific RC questions much faster! We will have the new schedule on our homepage once it all done.
So for this week, if you would, please post your RC questions in the comments below! I will answer them LIVE next Thursday at 5pm PST!
In this video we are talking more about how to find the CG on your plane and what happens if you move it more forward or backwards.
How to Find the CG for Your Plane
1) It should be on the instructions of your plane. Whatever it says, its safe to go just a wee nose heavy from that! Then for your next flight, move your battery slightly back and see how you like that.
2) Chuck glide it! If you are building a foamie, before you put all the electronics on it, straighten out the control surfaces with tape, put a small weight on the nose, and throw it over the grass! Adjust the weight until you have it doing a nice steady glide! Now you found your CG and put your electronics on from there!
3) Just guess. Make it what you think is a little nose heavy and just be ready to give your plane some up-trim after it takes off. This is fine, just land the plane, move the battery slightly back, reset your trim and repeat. This is what we do most of the time.
4) CG Calculator Page and Canard CG Calculator Page oh and THIS ONE too. These fancy pages only works if you have a very traditional "wing" and "tail". Remember, on all your foamies your nose and body also count as the "wing" so this locater page is not going to be good for you. We never use this page even though its very popular.
5) Benefits of Tail Heavy
Moving your CG farther back will give you more maneuverability like we did with our Wild Hawk and out Su-35 (just scroll down the pages). A gyro is greatly appreciated to help keep the plane steady doing this as the plane always wants to flip up!
Last Week's Question for the Class Was:
Spoilerons work so amazingly well on RC planes for high alpha, so why don't full size fighter jets use spoilerons for high alpha?
I think Inder-Nett gave the best answer. What he basically said is because the full size jets are so heavy, they need more lift than they need stability when they are doing high alpha do to their tremendous weight.
I think this is very true and explains all if not most of the reason why full size jets don't use spoilerons for high alpha.
Today's Questions for the Class:
Next week is our last Thursday Beginner RC Show. Within the next month we will be changing around our video schedules with different shows at different times so we can answer your specific RC questions much faster! We will have the new schedule on our homepage once it all done.
So for this week, if you would, please post your RC questions in the comments below! I will answer them LIVE next Thursday at 5pm PST!
Total Comments 7
Comments
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Question: Some beginner plains have a V shape wing (see from the front) with no ailerons. Could you talk about the dihedral angle of the wing, what is the effect on the airplane’s manoeuvrability?Posted March 27th, 2009 at 06:50 PM by DalToN_001 
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Question: Is it better to run a reciever with a seperate battery pack or run it from your ESC?
Question ( or request lol) : Are you gonna do a how-to vid on fitting rudders to a duel stabilizer fitted jet ( like the fa-18) ?Posted March 27th, 2009 at 08:39 PM by ApOsTle51
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You talked earlier about how rudders are so important. How come you didn't design rudders into some of your thrust vectoring jets? Is the weight penalty that great?
Posted March 27th, 2009 at 10:21 PM by JD_Flyer
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Good questions guys, I'll be answering them in today's class!
Posted April 2nd, 2009 at 09:04 PM by DavePowers 
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If your CG is forward of the recommended point (typically 1/3 back from the leading edge) and you have to use "up trim" to get it to fly level, it's going to be horrible when rolling inverted. I understand it's better to be slightly nose heavy than to be slightly tail heavy, but it's ideal to be right at the proper C/G point.
Posted April 4th, 2009 at 03:59 PM by HappyKillmore
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there is another way to find the CG:
6. Take a guess, put a Gyro on it and look what it does.
If the elevons stand up put the CG back
If the elevons point down and move alot put the CG to
the frontPosted April 26th, 2009 at 01:03 PM by MoTheG
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Nice ..
Posted March 3rd, 2010 at 09:09 AM by Flench
