Nose Heavy-Landing Problems
 

I have a 28% Edge 540T that is very difficult to land. On the test flights when your are coming in for a landing at a low speed approach, the airplane just doesn't want to sink. Instead it maintains the same altitude but starts flying nose high. Had to give it a good shot of down elevator to get it heading down. At first I thought that it was tail heavy. I was thinking that at very low airspeeds, a tail heavy airplane would cause the nose to rise. I then rechecked the balance and found it to be very nose heavy. I read somewhere that very nose heavy airplanes are hard to land. What bad landing characteristics would a very nose heavy airplane exhibit? Would this cause what I'm experincing? I rechecked the incidences and found that the engine had about 1/2 degree down thrust relative to the wing and the stab about 1/4 degree positive to the wing. I would think that is within acceptable limits. The airplane flys very well both rightside up and inverted. Level flight did require a small amount of up elevator trim. Any ideas??

RE: Nose Heavy-Landing Problems
 

Nose heavy planes tend to "run out of elevator" as you slow down for a landing. The slower you fly, the more back stick you have to give it to fly level and if extreme, you are at the limits of elevator travel long before you are slow enough to stall the wing. This results in a plane that can only be landed fast.
Also, if you have to push the stick forward a lot to fly level inverted, you are nose heavy.

Your symtoms say tail heavy to me. Recheck the specs and measuring points. Make sure you aren't making metric to english conversion mistakes.

RE: Nose Heavy-Landing Problems
 

It actually sounds like the airplane is fine. If it has any sort of trouble it's suffering from being "too light". To get around this floating on landing you need to do two things. Find a way to lower the idle speed on the engine and second to learn to fly it closer but not at the stall point. Both of these will provide more drag and let the model settle in like a champ.

If you try to fly nose high at idle and the model just stops coming down and flies on level then you've just got too much power and need to lower the idle speed a little more.

RE: Nose Heavy-Landing Problems
 

I vote tail heavy ---
screwing with incidence-thrust - really not a cure .

RE: Nose Heavy-Landing Problems
 

Tail heavy? I am not to sure of that. I am thinking that you have to much throttle or maybe the stab incedence is not right. Question,does it stall easy in normal flight? Tail heavy would make it stall at the drop of a hat,it seems to me. Nose heavy would make it stall hard if at all.

RE: Nose Heavy-Landing Problems
 

I vote for nose heavy. After all, stephensackro said it in his first post. What's to discuss?

So you've been landing one just recently, you think what you've read is maybe true?


Why not simply bring the balance back where it ought to be and see how the sucker flies?

RE: Nose Heavy-Landing Problems
 

Yes the airplane is light for it's size. It has a 86 inch wing span and weights 17 lbs. The engine a DA50, will idle down nice and low. The directions say to balance it at 33% to 36% back from leading edge of wing at fuselage. It is a Edge 540 so it has a straight leading edge with a tapered trailing edge. Cord at wing root is 19.5". That calculates to the CG being between 6.4" and 7.0". A recheck of the original balance point showed that it was balanced at 5.5" back which equals 28%. That was how it was flown for the test flights. I'm a little affraid to rebalance it according to the manufactor's recommendation since that will move the CG back 1 inch and will make it more tail heavy in relation to the first flights. We just have 2 flights on it so I guess I need to do some more flight testing.

RE: Nose Heavy-Landing Problems
 

Well crap -- if you balance at 33%of the root on the edge wing -you will be waaaaaaaay tail heavy
lemme splain-
say for argument - the root projected at c/l of fuselage is 20" annd the fuselage side line is 19.5.
the tip is likely 10" --so --the AVERAGE chord is 15".
when determining cg - use the avg chord as starting point.
this will be half way between tip and c/l of fuselage . irrespective of the span- a 15"chord is the average.-in this case.
now do 33% at 15"
what do you get ?
5".
that is maximum aft point for any flying except flat foamies. ideally 31% is about maxed on your bird.
when the model slows on landing -with NO elevator changes -it will drop the tail -IF tail heavy .
Fly a bunch of 3D setups -you will see this happens on any tail heavy setup.
Don't believe me?
call your favorite pro flyer - try Que que - you will get a similar answer - 31" at MAC is about max .

RE: Nose Heavy-Landing Problems
 

I agree with dick, re-read those instructions, sometimes things get lost in the translation. Some excellent flying planes come with crappy instructions obviously written by or translated by people who's first language is not English.
Anyway, how the plane flies is what should ultimately determine where the balance point is, not some words in a manual. This point may differ for different pilots.

Overly nose heavy planes:

Won't maintain altitude in knife edge even with full rudder.
Need large trim changes with different speeds, e.g. only fly well at one speed.
Can only be landed hot, you either have to dive to have enough airspeed to flare or land with a bit of throttle.
Tend to pull to the canopy in a downline if trimmed for level flight.
Won't snap roll.
Won't stall with power off, even with full back stick.
Need a lot of elevator for turns.

RE: Nose Heavy-Landing Problems
 

Screw the instructions. ;)

Figure this out for yourself. :D

Measure the airplane and go to geistware.com and plug the figures in with a request to show the CG for a 15% static margin. http://www.geistware.com/rcmodeling/cg_super_calc.htm

This application is tried and true. It ought to be, it's the same aerodynamic computations that've been used with completel success for years and years and years. And it takes almost no time or effort and certainly not any special skill. It considers everything that ought to be considered.

Once you've input the measurements, you can repeat the thing with 10%, 15%, 20%, 25% static margin requests and get a real handle on where the CG should be.

I've had newbies fly trainers with the static margin from 10% to 25%. Their trainers all flew just as safely after they'd been trimmed to level flight and the elevator rigging had been tuned to make the stick movement within reason.

You do not help yourself by having a hugely over balanced CG toward noseheavy. Your airplane isn't going to be any safer, about all that happens is your elevator goes more and more numb and overburdened, when you balance the airplane VERY noseheavy to "be safe". You're not making it safer.

Hey, you can argue around in circles forever, or simply take 10 minutes and get accurate information.
Just remember if you're considering the advice you've gotten so far, most of the advisers were arguing whether or not your airplane was nose heavy or tail heavy AFTER YOU'D STATED CLEARLY THAT YOU'D CHECKED THE BALANCE AND IT WAS VERY NOSEHEAVY. hehehe..... you wanta take advice from people who don't even read what you wrote? Just kidding.....

RE: Nose Heavy-Landing Problems
 

Has it ever occured to you that instruction manuals are written by people who are not infallible? Or are written by people who did not design the plane and mistranslated what the designer meant to say?

"I read it in a book so it's obviously correct."[&o]

RE: Nose Heavy-Landing Problems
 

Sorry guys...Im going to have to agree with Bruce on this one. People sometime rush too quickly to change the balance on a plane that is fine in reality. Tailheavy would mean the plane would feel unstable around the pitch axis. A floater like yours means your wingloading is just low. Nothing else. A nose high approach is just the plane bleeding off speed. The slight downthurse angle will also help the plane settle in a slight nose high attitude. To be 100% just add weight right on the CG to bring it close to the original specs and see how it flies then...but I really just think you just have a floater.

RE: Nose Heavy-Landing Problems
 

those models ain't floaters --

RE: Nose Heavy-Landing Problems
 

Thanks one and all for your help. Went to the geistware.com website and put in my figures. Very nice site. A little confusing but once you read all the terms about 9 times it starts to make sense. Anyway according to those calculations the CG was too far back from where we originally flew it. The recommended CG in the instructions were even farther off for normal flying. Will fly it this weekend and see what happens.

RE: Nose Heavy-Landing Problems
 

don't feel bad - it's part of the larnin curve .
We learned that stuf from the years spent at Sam Houston Institute of Technical experience.
after a while you wil see n feel the correct CG -easily.
Calculations?
We don need no steekin calculations --

RE: Nose Heavy-Landing Problems
 

If the wingloading (weight/wing area) is sufficently low (outside of the normal range for that design), it will float...no matter what the original design intentions. That's just basic aerodynamics.

RE: Nose Heavy-Landing Problems
 

sure - however that particular model (the Paty Wagstaff Great Planes kit) -- it ain't a floater ..