c.g how far is too far
09-08-2006 | 04:58 PM
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From: holly,
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c.g how far is too far
hey i got a goldberg hot stix 40 w/ a o.s 46ax in it, has pleanty of power and massive control surfaces.. on high rates probley 45-50deg throw yet is dosent like to hold a knife edge i got the c.g about half way between the front and rear marks.. moving it to the rear will help knife edge?? and if so how far past the rear mark can i go before it's a lawn dart ????/ to unstable to fly..thanx kind of new @ the aerobat stuff
09-09-2006 | 06:33 AM
#3
RE: c.g how far is too far
On a side note, once you get to the rear limit take small steps if you want to go any further. I have the CG on my GP ultimate behind the rear limit. At this point it is slightly unstable in pitch and is difficult to fly but it does do crazy tumbles.
09-09-2006 | 09:01 AM
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From: Ellensburg,
WA
RE: c.g how far is too far
I have a the 40 size WILD STICK...
THE WORST FLYING PLANE THAT I HAVE EVER OWNED...[
]I think the small wing cord and the flaps just take out
any 3d type flying...
09-10-2006 | 02:59 PM
#5
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RE: c.g how far is too far
Knife edge has an equal amount to do with fuselage side area as it does with rudder throw and/or surface area. That Hot Stix has practically no side surface area, much like my Ultra Stick, so I'll tell you what I did:
1)Bring the CG back as far as you can while still feeling comfortable with general flying. My mini Ultrastick and My Ultra Stick 60 were actually in a very flyeable CG, only 1/8" back for the Mini and 3/8" back on the 60. The CG does have an effect on KE flight just like it does on any other flight characteristic, but it will not make or break the planes ability to knife edge. Still, it is the first step in setting up ANY airplane, so set it first.
2)Put your rudder on high rates. You need a minimum of 35 degrees, but 45 is better.
3)Mix out all tendancies other than yaw when you apply the rudder. If you don't, knife edge will be a ROYAL pain! On my Ultrasticks, I need approximately 10-12% down-elevator mix and 12-15% opposite aileron mix just to make it flyeable with rudder application! Designs like yours and my Ultrastick are actually so bad that completely mixing out all bad tendancies is pretty much impossible, but you need to get it to where it is flyeable.
4) Now, when entering knife edge, you cannot simply roll it over and apply rudder. It will simply drop because the fuselage has very little side surface area and cannot maintain altitude without the help of the motor's thrust. To keep it at altitude or even be able to climb, you need to pitch the plane up prior to rolling over to knife edge so the fuse is at a positive angle of attack and the propellor's thrust is also helping to maintain altitude. You will find that it pretty much takes full rudder deflection and a good deal of throttle. Getting it to climp usually means adding power.
Typically, I don't just do knife edge. I usually blend it into other maneuvers so it doesn't look like you are having to work just to do a knife edge pass! Try a 1-1/4 positive snap to knife edge. The snap will put the fuse at the positive angle of attack it needs. Or pull into a hover. Obviuosly, maintaining the hover is cool, but if it starts to fall out just roll into KE and fly it out...
1)Bring the CG back as far as you can while still feeling comfortable with general flying. My mini Ultrastick and My Ultra Stick 60 were actually in a very flyeable CG, only 1/8" back for the Mini and 3/8" back on the 60. The CG does have an effect on KE flight just like it does on any other flight characteristic, but it will not make or break the planes ability to knife edge. Still, it is the first step in setting up ANY airplane, so set it first.
2)Put your rudder on high rates. You need a minimum of 35 degrees, but 45 is better.
3)Mix out all tendancies other than yaw when you apply the rudder. If you don't, knife edge will be a ROYAL pain! On my Ultrasticks, I need approximately 10-12% down-elevator mix and 12-15% opposite aileron mix just to make it flyeable with rudder application! Designs like yours and my Ultrastick are actually so bad that completely mixing out all bad tendancies is pretty much impossible, but you need to get it to where it is flyeable.
4) Now, when entering knife edge, you cannot simply roll it over and apply rudder. It will simply drop because the fuselage has very little side surface area and cannot maintain altitude without the help of the motor's thrust. To keep it at altitude or even be able to climb, you need to pitch the plane up prior to rolling over to knife edge so the fuse is at a positive angle of attack and the propellor's thrust is also helping to maintain altitude. You will find that it pretty much takes full rudder deflection and a good deal of throttle. Getting it to climp usually means adding power.
Typically, I don't just do knife edge. I usually blend it into other maneuvers so it doesn't look like you are having to work just to do a knife edge pass! Try a 1-1/4 positive snap to knife edge. The snap will put the fuse at the positive angle of attack it needs. Or pull into a hover. Obviuosly, maintaining the hover is cool, but if it starts to fall out just roll into KE and fly it out...
09-10-2006 | 09:53 PM
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From: holly,
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RE: c.g how far is too far
thanx.. i'll try a couple things and give it a go next time out.. thanx for the input on the fuse side area.i did'ent know that 
