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Hands Off Inverted Flight ????

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Hands Off Inverted Flight ????

Old 12-18-2008, 08:56 AM
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Witterings
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Default Hands Off Inverted Flight ????

Generally when people refer to "Hands Off Inverted Flight" with highly aerobatic planes like Extra's, Yak's, and Edge's as a general rule of thumb do you mean literally no down elevator at all or is the saying generally taken as "some" but little down elevator.
My reason for asking I've mainly flown an Acromaster and more recently Multiplex's Parkmaster as well and both of these I've moved CoG back until they actually climb inverted during the process of finding where I personally like it and then adjusted so that there literally is virtually none at all and if I move the battery back another couple of millimetres then it'll climb inverted instead.
I've also have a few Balsa 3D planes, all made by very well know / reputed manufacturers and yet whatever I do they all need a signifigent amount more down elevator in comparison to the extent having not flown one for a while it nearly cost me the plane as there just didn't seem to be any response as it headed sharply towards the ground and I had give a LOT more down to stop it compared to the others.
I've been through and checked things like the evelator deflecting to a similar amount and Expo settings etc, I've moved CoG way, way behind manaufacturers recommended to see if it makes a difference and tried up to 4 degrees of downthrust to the extent that if you trim the plane at 50% throttle and then increase throttle you can visibly see it head down.

I'd be interested to hear other peoples experiences and if you do literally get it to Hands Off Inverted or whether the term really means virtually no down elevator

Any input much appreciated !!!!!
Old 12-18-2008, 10:37 AM
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daveopam
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Default RE: Hands Off Inverted Flight ????

I have always assumed hands off meant no stick input. I fly mostly 3D. I have 1 plane that will fly hands off inverted and hold altitude. I have a F50X that climbs and a few that have a slight dive. I don't use the hands off inverted thing to trim my planes. I adjust the CG till they fly like I want them to. However the inverted flight turns out, so be it.
That being said it can be a good tool to set the CG on some planes. A lot of people build the plane trim it for straight and level flight and forget it. The problem is if your plane is nose heavy it may require a few clicks of up elev trim to make it straight and level. Then when you roll it over, those few clicks of up are now pulling to the ground. Hope this helps a little. I am not smart enough to talk about thrust and wing incidence and it's effect on trim. Maybe someone will answer that is.

David
Old 12-18-2008, 10:46 AM
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krayzc-RCU
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Default RE: Hands Off Inverted Flight ????

I adjust for a hands off or a very close to hands off inverted then I adjust up/down thrust, right/left thrust, and mixes.......
Old 12-18-2008, 11:59 AM
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rmenke
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Default RE: Hands Off Inverted Flight ????

Widtterings:

Krayze-RCU has it right on, but there is really no right or wrong. The process started with trimming pattern airplanes years ago, a good method to find out if your thrust lines are correct (engine, wing, elevator). If off kilter the bird would be a dog. Today's pattern birds have adjustable wings and elevator sections for this purposes, and with digital incline meeters things are relatively easy to set up. Us untrustilng old dogs still go through a trim process to get the bird to fly a pattern with as few corrections as possible. Pilot input equals possible error and reduction of score. Many contests are won by one point, so everything you can do to get things right on is done. I had a bird in the 1960's that rolled, flew inverted and ran up and down lines with no imput corrections needed. It got me a lot of underserved trophies, but took them anyway. Was also the first retract equiped plane on the west coast. Several guys on the East coast claimed to be flying retracts at about the same time. We made ours on the shop vise with a lot of trial and error. No such thing as retract servos in those days, so if you stalled a servo you were a dead duck. ENJOY
Old 12-18-2008, 12:09 PM
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Default RE: Hands Off Inverted Flight ????

Most of my 3D ships are darn near hands off. I don't like them to climb inverted. I do like krayzc-RCU said set the CG first and then go with motor angles and maybe wing incidence/decalage angles if the KE performance is strange. As a last resort, use radio mixes.

On the slope, I set the CG so the plane is most efficient (ie, glides easily, snaps well and flys inverted very well). After I get the CG so it will do that on the slope, I trim so I'm always holding some up elevator to maintain level flight but that's a special condition I impose on myself for how I like to handle the lift gradient changes far and close to the slope edge. I never want to need to give down elevator to maintain level flight, so I trim down elevator beforehand and that changes depending on the lift of the day. The flip side is that inverted performance is very good. Keep in mind slope airfoils are usually NOT symmetrical.

Old 12-20-2008, 10:30 AM
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slostick
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Default RE: Hands Off Inverted Flight ????

Different planes have different characteristics. Some will fly with no elevator input upright and inverted. I start with balance in the three dimensions. I trim on the first flights. My Fancy Foam Edge and Insane Foamies Yak were hands off on elevator for upright and inverted flight. Little top rudder was needed for KE. The balance was per manufacturer specifications.
Old 12-20-2008, 02:07 PM
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Default RE: Hands Off Inverted Flight ????

On balsa 3d Extra type planes I set them up with a neutal CG....meaning hands off inverted. You can set them up to suit your style. CG more forward gives a better sport setup but requires a bit of down elevator inverted. CG back some gives better 3d harrier and hover but the plane will climb inverted. Me...I like to both kinds of flying so I go neutral. Its all a compromise and you can pick your style.
Old 12-23-2008, 07:46 PM
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Yaniel
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Default RE: Hands Off Inverted Flight ????

i only 3d flat foamies but i always set my cg to be neutral inverted and normal. i also make sure it doesnt tuck or pull out of a power off vertical downline
Old 01-06-2009, 05:08 AM
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Default RE: Hands Off Inverted Flight ????

My EF Yak-54 is hands off inverted and upright with no stick input needed to maintain. Took a lot of moving the battery to find the sweet spot and just make a mark inside the fuselage for different batteries. I would double check your rear horizontal stab incidence and thrust line. Even with a rearward CG mine does pattern nice. It is nice to be able to flip inverted really low during a pass and not worry about having to push the stick forward to catch it [X(]
Old 01-06-2009, 08:22 AM
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Witterings
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Default RE: Hands Off Inverted Flight ????


ORIGINAL: scottfl78

My EF Yak-54 is hands off inverted and upright with no stick input needed to maintain. Took a lot of moving the battery to find the sweet spot and just make a mark inside the fuselage for different batteries. I would double check your rear horizontal stab incidence and thrust line. Even with a rearward CG mine does pattern nice. It is nice to be able to flip inverted really low during a pass and not worry about having to push the stick forward to catch it [X(]
Scott,
You've hit the nail on the head, when you get used to one that needs no input and then go to one that does need some it could get awfully expensive with planes if you're low to the ground as you don't have the time to react !!!!!!!
Personally I love nothing more than doing inverted harriers 3 / 5 ft off the ground and just floating around and hence why the difference between them causes me such a a problem and why I was interested to see what other people's experiences were.
Thanks to everone for all the replies !!!!!

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