RickP

My Feedback: (2)

Guys,
I'm still working at the CG on my 2.6 Extra. I thought the plane was pretty good and through trial and error now have moved my two 2500 NIMH packs back little by little to over 8" back!!!. Problem is that it feels better, but not by a whole lot. I get the feeling I need to keep going, but how will I know I went to far. Before I even started the plane passed all of the CG tests, 90deg bank no change. My only hint was up stick when inverted. I still feel like it is too much up stick pressure to maintain level.
I'm just afraid to go to far and have it un-flyable. I just can't believe I shifted that much weight and have not become overly tail heavy yet. Anybody have any comments? Gotta keep going right?
RickP

Blow n Go

For a plane that size it takes a good bit of weight movement to significantly change the CG. Keep going until it:
A) Takes no forward stick to hold level inverted.
B) You are unable to hold straight and level flight without it darting up and down.
C) You find yourself steadily adding forward stick on your landing approaches.

In other words, keep doing what you're doing until it starts to act "funny", and then back up a little. It is unlikely you would make it unflyable if you move the batteries a few inches at a time.

Good luck,

CJ

RevGQ

I feel your pain dude. I would suggest that you know you have reached your limit when your begin to feel uncomfortable in landing your plane, particularly in windy conditions. What you are attempting is to set up the plane to fly in an unstable condition. The degree of unstability is a matter of feel for each pilot. Being such, you will also want to experiment with your exponential rate. But most important I think is how comfortable are your landings. Hope my two pennies help.

RevGQ

RickP: just a P.S.: one of the guys at my local flies 3D very well. Whenever I enquire of where he has placed his c.g., he states that he pretty much follows the designers location, and most have been approximately 28-29% of the chord. I really do think it is a matter of feel.

OnTheEdge

Hi Rick, are you looking to set your C.G. up for IMAC or for 3D/freestyle? If you need "up elevator" when inverted, then you already are too tail heavy for sequence flying.

If you are trying to get the C.G. back for 3D, then CJ is correct, it can take a bit of weight shifting to move the C.G. back on a plane that size. What I do is leave my batteries where I want them for sequence flying. Then I add weight (up to 8 oz) to a phenolic I have in the rear of the plane just infront of the stab tub. At 8 oz, it is getting a little tough to land but is still not unstable.

RCAIR-BAM

Rick
If you get to the point of the plane darting up and down get it down while there's still fuel over the cg and hope you don't snap the plane in on the final. there not fun to land like that. I had a lanier cap knife edge 3' off the ground with two people running because it snapped on me when i went to flare. Not really fun. be careful.

Yurri said this plane like to be nose heavy and i tend to believe him. Next time I see you I'll let you fly the plane he setup for Eddie Meyer.
Kevin

Geistware

My Feedback: (16)

I would say to notice how the plane responds when you go from full speed to stall speed.
If as you reduce the throttle the plane pitches up, then you know you are too tail heavy

Doug Cronkhite

My Feedback: (34)

Actually.. the best in-flight test you can do is, pull to a 45 degree upline, roll inverted. If you start to climb, you're too tailheavy. If it slowly drops the nose, you're ok. I prefer a nose-heavy setup for precision flying.

RickP

My Feedback: (2)

Mark,
Sorry, I ment forward on the stick as in "down elevator". Didn't make it too clear - sorry. I want to set this plane up for IMAC style flying, I noticed that the changes I have made have let me fly straighter lines. I think I need to keep going but I'm just looking for reassurance that I'm doing the right thing. I tend to get to complacent and not want to make changes - I should have done this a long time ago.

dcronkhite,
Your assesment is all I really have to go by that tells me anything. If I pull to 45 and roll to inverted the plane will start to pull to the canopy. The more it pulls the worse it gets, so I assume that I should keep going. Tonys reccomendation has some merit too, but If I have thrust line problems that will mask what I'm aiming for. I'll pay attention to it this weekend and keep at it.

Kevin,
Trying to keep people ducking for cover? LOL, that's what I'm trying to prevent I had a 1/4 scale Edge that was totally nutral inverted and upright. I really feel this plane should feel the same way, and want to get there.
RickP

aerolou

My Feedback: (3)

I only use the manufacturers recommendation as a starting point.
After the first flight I adjust until it feels good to me. Usually I end up moving the CG back.
I have no idea where my airplanes actually balance right now, I only know I like the way they fly.

Lou

RickP

My Feedback: (2)

That's kind of how I feel. I just keep shifting it back, I'm just suprised that I havent gone too far yet.
RickP

rmh

I had fun with the good ol guys on the aerodynamics page
I noted that "if the plane is light enough the CG did not matter
Also if it was too heavy - it still did not matter.
some went nuts - they didn't get the "logic" .
some got it - understood
some said CG had nothin to do with weight--
On the little flat foam lectrics -you can test this idea and never be out over 5 bucks if it crashes.
I can move the cg way back -- and just head into vectored flight - -tricky -but it is flying.
add too much weight - -it simply won't fly - so th cg means nuthin.
all in all -just shift till it hurts-or feels good.

RickP

My Feedback: (2)

Okay,
I'm getting real close now. First hint is that the tail is starting to settle on final coming in for landing. I don't mind it at all - but I'm just glad I'm finding the rearward position. Later on Saturday I busted up my first prop on this plane and put on a wood one W/O the spinner and got even more tail heavy - I liked it even better LOL. I think that's close to the limit though because gettin it to stall into the spin is getting real difficult.
RickP

3D Joy

It should be easier to stall into a spin with a tail heavy plane...

Mike Bogh

My Feedback: (14)

I have flown many "too tail heavy" aircraft, and for me what works best in a windy landing condition is to add a few clicks of down elevator, (or just mix a bit of down on a switch marked landing).
This is not good for IMAC, but better for 3D flying.
The down ele trim makes you keep a wee bit of back pressure on the stick all the way to flair, thereby eliminating the ballooning effect.
Again everybody I know prefers a bit more "nose heavy' for IMAC, tends to be more stable and predictable.

krayzc-RCU

My Feedback: (31)

with the size of some of the wings on todays planes you can get away with a very aft cg. i perfer hands off or very very close to hands off inverted..... mixes take care of the throttle to elevator setting at low throttle for landings....

on my 1st flights with my 40% radiocraft i balance it and then added 8 oz to the nose to be safe for that maiden. i removed 2 oz at a time per flight and could not tell i had removed any weight.

Geistware

My Feedback: (16)

krayzc-RCU, nice plane man!

krayzc-RCU

My Feedback: (31)

thanks Geistware whats the new bird you have in your corner for 2004?

i have one of those wh specials coming
+
i need a hype 3d and the dp edge smaller one

RickP

My Feedback: (2)

Yeah I noticed that.
All that weight shifting and I only had a click of elevator trim change. I also like a nutral handling plane inverted and right side up.
RickP

Doug Cronkhite

My Feedback: (34)

I've never found an airplane that felt locked in when balanced hands off both upright and inverted. I've always preferred a forward CG for precision flying. The aft CG makes freestyle easier, but the tradeoff is less precision.

RickP

My Feedback: (2)

Doug,
Thanks for your input - but what I've realized is that I was outta the ball park nose heavy. Moving the CG back actually made my plane track better. I can actually start to think about drawing lines in the sky The point to this thread is how far should I keep going untill I've past the point where I'm adding too much tail weight - and start to loose precision, again? I was hoping for something qualitative because I actually flew for a year thinking that my plane was "On the Money" and I was out of the ball park.
Thanks
RickP

3Dfalcon

Hey RickP,

Remember me.

Long time no talk.

Went through the big "D" and kinda slacked off the end of the last IMAC/SCAT season.

Looks like your still doing well with your FiberClassics.

Just got back on RCU and things have changed.

Saw your post so I wanted to comment.

I have been flying hard since I talked to you over a year ago and this is what I have found to work for CG settings on most aerobatic designs.

I fly alot of 3D and sequence and have played with CG alot on 5- 2.6 Extras,2- 3.0 extras and I am now using a 40% 3W competition Extra (Blood scheem) for my primary IMAC plane for advanced this year.

Just as Doug C. stated,an acomplished competition pilot, I too do not like a plane that needs zero push on inverted. Its actually dangerous! I love flying inverted and like to fly pretty low figure eights and other fun practice stuff. The only way I can keep my plane together through all the aggressive low inveted flight I do is to ALWAYS have some negative push to the stick. Thats how you know you are inverted if you are out there a ways and youve lost perspective for that second.

Also if you aspire to be a IMAC pilot then as soon as you hit Intermediate,half the flight is on the inverted line.
Ive played with your exact setup alot and this is my suggestion. I like the 2.6 a bit on the tail heavy side of the spectrum, as I think your starting to see. It takes alot more weight than you might think.
Ive helped 5-6 friends with the same plane setup and after quite a bit of lead they all started to freek. Once the plane was balanced proporly they were amazed how much better there planes flew.

Heres the trick. Keep adding weight, or moving components,until the plane will do this:

Roll to inverted and get the plane flying straight and level. Make sure you are at a half throttel setting. Now let off the pressure on the elevator and start counting seconds and look at the sink rate. The plane should fly level for about a 2- 3 count before it starts a fall back.

At this CG I am able to fly inverted with just a light push and my up and down lies are true.

I also get the joy of not having to do something as unnatural as push down on landings.

Hope this Info Helps

Good Luck

Dave

RickP

My Feedback: (2)

Hey Dave,
Sure I remember - you are the one that started this all LOL. Sorry to hear about the "D" that really sux and I hope it all works out for ya. As for the 2.6 it's still going strong but starting to show some wear. Check out the Giant scale colum http://www.rcuniverse.com/forum/m_14...page_39/tm.htm Where I just replaced my gear mount.
As you gessed this will be my first full year in basic and I am just starting to figure out what I like and don't like. The one thing I noticed now is that my down lines are right on locked solid, it's awsome. Come out of the spin and "BAM" ( Hi Rob) it's the best downline I've ever done.
I'm going to keep going till I just go over the edge and come back a little. Right now I'm just hinting on leaning forward on the stick when landing - so I know I'm getting close. I think I'm going to start working on right thrust now, once I get the CG good and where I want it. Time to get the uplines matching the downlines...
RickP