I got the plane up for a short flight before dark last night, after a little change in elevator trim it flew great. I really noticed a difference in knife edges, it took full rudder before to hold a knife edge with about 3/4 throttle and this time it took very little rudder and less then half throttle. When landing the approach was good and no more wing drops, but as it got a few feet from the ground I found I was using a lot of elevator to hold the nose up and by the time I was at full elevator it stalled and nosed in. No damage to the plane, just my ego. Also I had to still put up trim in the elevator, could it be that I need to move the CG more? There was definitely a change for the better but it seems like this plane wants to come in hot especially just before flair to keep the nose up. The plane doesn't really float on it's wings on landings.

It sounds like you are on the right track. The way my airplanes are set up, it takes about 1/4 stick to flare with a nice landing. In normal mode I have about 15 degrees deflection both directions so a total travel of 30 degrees. Even less in snap roll mode. The reason the airplane stalled and dropped the nose is because you are still nose heavy. What happened is you found the approach to be more controlable while holding the up elevator but soon the airspeed needed to keep the elevator effective was gone and she gave up. Once you get the CG in the sweetspot it wil no longer do that. Thats the part of his facy diagram that RCTECH left out is that the elevator increasing AOA can overpower the heavy nose until airspeed drops and the elevator looses effectiveness.

The fact that it stalled indicates that there is sufficient elevator authority, and the balance is fine. You simply exceeded the wings stall angle. Doing this as the mainwheels touch is good, doing it a couple of feet high will make for untidyness. Perhaps you need to do lots of 'touch and goes' to refine the landing process with this model, rather trying to disguise a lack of practise with electronic and aerodynamic tweaking. Take the thing out, and do some concentrated 'flying with purpose' practising those things you do not do well, and always do 6 or more 'touch and go' landings, being really honest with youself and only stopping when you know that you have got it right. Throttle for glide slope control, elevator for speed control. It is unlikely that the tailplane/elevator stopped working, with prop slipstream over the tail there will always be some lift generated by the tail. If the model will stall and spin the tail is working and is keeping the wing stalled, the balance is fine.
Evan, WB #12.

Why do you guys seem to think that elevator authority is not airspeed dependant? He's on the right track with the CG shift. Let's all give him a chance to refine it some more and report back.

The other thing to remember is, changing the engine has made this a whole new creature, and it will never fly exactly the same same as before. The prop size and pitch has changed and the gross weight has changed. He is going to have to learn to fly it all over again. It will take time, patience and practice to get it to where he is comfortable with it again.

Elevator sensitivity is speed dependant, granted, and balance dependant. Authority, whether it keeps working or not, cannot be speed sensitive with powered models, else those '3D' guys would be stalling their tailplanes all over the place. No, in this case, the fact that he can stall the wing, which is angle dependant, shows that the balance and elevator authority is not the issue. Rather it is when the stall is occuring, in this case a little too soon, which is more of a practise thing. When (what speed) the stall occurs is weight dependant, of course.
Evan, WB #12.

At idle the air flow from the prop is very near the same speed as the relative wind and on landing the makes the elevator very speed dependent.

Again, if the elevator has sufficient authority to stall the wing on landing (slow speed) then the speed dependancy does not matter, the wing has already stopped flying. Sensitivity is another matter. Generally, unless the balance is a long way forward, and the elevator movement is minimal, then the wing will stall before the elevator stops working. So far I have not met a model which runs out of elevator before the wing stalls, although for some trainer types I can see that deliberately reducing the elevator effectivness could be an idea in the 'ab-initio' stages...but perhaps I haven't been exposed to enough 'other models' yet...Heck, even my old 'Air Trials Sportster' will stall with sufficient provocation. At the other end of the scale I have a near 1/4 scale FW190A-8 which balances close to 20% MAC, and it will do a near stall 3 point with the scale tailplane, which is only around 13% of the wing area. As for my aerobatic types, well, apart from Taurus which is a bit iffy about its stall, they really have to stall, and 'on command'. I haven't been able to detect yet any of them which runs out of elevator before running out of speed. Does the sensitivity (feel) change with speed? Yes, of course, but they all still work, even at speeds that the wing refuses to operate at. I still think that the OP needs to do a bit more practise, specially if he is happy with the balance as it is.
Evan, WB #12.

You've got plenty of expert advice from latest input. What I can say is that there's a big change on your CG that is not familiar which affect performance compare from your previous setup. If you remember my post that AOA must be reduced when moving CG backward to avoid early decaying of airspeed. Since you've mentioned that without raising your nose the aircraft is coming in hot, that's because of the energy of an aircraft with lesser drag. You have to accept that you've gain favor control from flight and just familarization on landing. Reduce elevator slightly, hold it and use throttle to control descend rate. Also be careful when landing on windy without reducing AOA. Don't move the CG more back it would make it worse. Better if you move it slightly forward but you can leave it as it is right now if you're comfortable.

I'll share you my hornet with CG at leading egde of MAC, at cruising speed of around 127-mph the trim is almost zero. Airborne speed for around 80-mph has aprox 3-deg of trim on level flight for 42-lb of mass. Max engine thrust is 30-lb. Landing speed is very slow with at least 6-deg on elevator. Average wing loading is approximately 6-lb/sq ft.

http://www.youtube.com/watch?v=XxKOeb2hStw

Explain this. An airplane is capable of stalling no matter where the CG is. How do you know what AOA he had when the stall happened? Did you even read what engine he has on this airplane? Look it up, the engine weight is almost double what the airplane was designed for, how can than not be an indicator that he is nose heavy especially when what he is describing is classic nose heavy conditions. Guys, we are not talking about a trainer, a FW 190 and F-18 of anyother thing you may have flown. We are talking about an Extra. I have flown many of them, I have lots of IMAC wins under my belt, unless you have intamite knowledge of this aircraft please just allow the OP to continue with the CG adjustments and let him comment back. He already said he was pleased with the first adjustment.

Another issue that may be contributing to your problem is with this larger engine you may have too much pull at idle. To compensate you are having to increase your AOA to get on the inside of the lift/drag curve to compensate for the excess thrust. There could be a very fine line between enough drag and enough lift that you are on the ragged edge on landing. You might think about trying a larger diameter prop with lower pitch, or a three blade with lower pitch.

Aviator 25 - Just want to add one more since this page is where you've got plenty of helpful info for your plane beginning from a post right after your test flight report. Now also including highlights and hot topic... I agree that speedracerntrixie is expert on this plane but pimmnz is correct on his evaluation that speedracerntrixie actually didn't notice that support his analysis.

speedracerntrixie - you always misunderstood us here, you don't know how to appreciate others comment, I commented that the latest input right after I left was an expert advice. But I don't want to exclude pmzz and cfircav8r becuase their input are also correct and valuable too.

I share my hornet because to show you all of you are correct as elevator is very dependent with airspeed even if it's nose heavy, becuase the aircraft we are talking about is nose heavy and has increase weight and power. I'm sport minded person and about to congratulate you for leading this thread having the best advice for now and for Aviator 25 on solving the problem but how would you get the joy of helping if all the guys don't want to reply your comment anymore. This thread is becoming more interesting because of them also.

Here's how it goes for me, the pitch moment cause by the elevator is affected by airspeed at exponential rate while CG is linear. When aircraft is on high AOA and descending, the resultant air stream on the tail can be influence by the propeller, horizontal wind and air flow caused by descending slope. The tail plane with no camber produce lift relative to air stream because of its AOA. When there's elevator input the tail wing has negative camber which produces down lift relative to airspeed. When CG is located at 25% of MAC and C/L reaches at the same point, the elevator for steady state must be zero lift but it is very difficult to have zero lift without precision equipment. At this time the elevator can easily be influenced by above air stream factors. Because airflow has exponential factors and there's no counter force that controls pitch acceleration. Because of the high drag and lift employed by high AOA the aircraft couldn't maintain its airspeed without stall eventually. As per speedracerntrixie mentioned the elevator loses it's down wash and give up to take over by the underneath wind caused by fall as pimmnz mentioned and generates pitch down moment to the entire aircraft. The solution I'm thinking about is to reduce AOA slightly as per mentioned before with the latest CG then increase on flaring.

OK Speed, here's how I see it. The stall angle of any wing is fixed, it won't change. OP reckons he's stalling at too high a speed/height. Just about all model wings stall around 8~9 deg AOA. That's what the stall angle of his wing will be. An Extra is no different than any other model airplane, his wing will stall around that angle. His elevator is getting the wing to that angle, and at landing time, slow speed. The only thing that can change this wings speed of stall is weight. He has a new, heavier engine so his stalling speed is going to be higher than before. Yes, the balance may be forward of what it was, but that won't change the stall angle, it will change elevator sensitivity (feel) and authority, but he is still stalling the model, and I would guess the elevator stick is closer to full up than before. So authority is fine, balance is fine, sensitivity is down. He could increase the sensitivity by moving the balance back, but that won't change the stall angle, or speed, unless he adds weight at the back, in which case stall speed will increase again and the stall will happen even earlier. New engine, heavier airplane, higher stall speed, need to practise landings for the new conditions. You can futz about with the balance and elevator movement, but it won't change the basic problem.
Evan, WB #12.

I agree with your points, however I also agree that this A/C would benifit from a more aft (within reason) CG. It will reduce the wing loading and really help it come alive in the air. He will definitely need to relearn its characteristics.

I don't understand how shifting the balance back will reduce the wing loading...You can move stuff about in the fuselage, but the weight and loading will remain the same, or you can add weight at the back, and loading will increase. Or so I thought...
Evan, WB #12.

If you can shift the weight (not add) you will require less down force on the tail. That down force adds to the down force caused by gravity. So weight remains the same but loading goes down.

Yeah, I've heard that one before...the only problem I have with it is that the decrease in aerodynamic loading would be very small, and that the tail, as a stabiliser, will have lift loads both at both positive and negative values through the flight, that is, it's constantly changing. Balance only affects pitch stability (sensitivity). Loading is simply an arithmetical value (weight divided by wing area). To make a measurable difference in this fellows landing characteristics he really needs to lighten the airframe. As an Extra, I bet the wing section is also designed to have a clean stall break, ie it will have a sharpish leading edge, which is also not helping in this situation. In the end the solution is just to learn to live with it, and practise enough landings to be able to be as close to the stall as the wheels touch as possible.
Evan, WB #12.

wing loading remains the same BUT the downforce increases - increased drag- actually improving how many planes fly!
efficiency - drag vs lift DECREASES It's all a trade off - no magic airfoils - no magic cgs - just different setups for different tasks
Today we flew everything from a Senior Kadet weighing 6.2 lbs -to pattern models and 3D setups - all different cg-s all different wing loading all different airfoils.

Yes it is small, but it does exist, and yes the tail lifts up or down. So does the wing, and the amount of, extra or less, tail force required to balance for a given CG will be proportional, affecting the "weight" the wing must carry. At the end of the day he will have to adjust his flying, but he can spend a little time fine tuning and may find a little improvement.

One thing many have a problem remembering is that a stall, depending on how you define it is NOT a bad thing. AS LONG AS the stall is symmetrical. Its only when the wingtips stall while the inner wing or opposite wing is creating far more lift that problems occur.

Technically a stall in and of itself is NOT a problem. The wing is still "flying", just very inefficiently. Most people think that when a wing is "stalled" it is providing no lift. This is not true. What is true is that the separation bubble has broken lowering the lift coefficient.

All this talk of CG is so much garbage really. All that is showing is how much tail authority one has on their model.

PS. Dual function ailerons are a wonderful thing. Flip the switch upon landing causing your ailerons to ONLY go UP and not down will prevent wing stall. Likewise add in the function that the ailerons "center" is moved upwards as well is also a sweet function.

PPS. All "real" computer controlled airplanes use spoilerons at low speed. When mechanically linked control systems have more limitations regarding their use, though possible through the use of CAMs.

I've got a 3D plane that was flown an entire flight with a dead elevator servo. I noticed a change in how tight it could loop, but was practicing hovering for the most part. All pitch control was obtained with the flaperons active and the landing was smooth as silk.
I figure that the CG and wing loading played a big part in this.

CG talk is garbage? So you don't balance your planes? If it were garbage then why would "real computer controlled airplanes" require the CG to be within a specified range. That would be because too far forward and you loose tail authority (yes I know you said that), but too far aft you loose pitch stability, such that even a computer can't compensate. Long range aircraft generally keep the CG more aft during cruise to noticeably increase range (amazing how such a small change in load can help so much.) I am saying fine tune your airplane, sure you can fly almost anything if its kinda close on balance, incidence, and weight, but don't they fly so much nicer when it is adjusted to normal ranges. What Speed and I are advising will benefit the performance throughout the envelope, not just on landing. If after tweaking it a little he still feels it has bad tendencies then by all means he should try some reflex. If you choose to fly a TLAR airplane be my guest, but not everybody is willing to accept mediocre on an A/C that is made to perform, and without the fine tuning adding reflex is a second rate fix on what is supposed to be a first rate A/C.

Well, I have to call this one done. Everyone is entitled to their opinion and I have expressed mine here. I have a proven competition record to back up my methods. Time will be short next week as I am preparing for a pattern contest next weekend. I'll leave the thread to you guys and hope that the OP will try a few things and continue to report back here. Have fun everyone.

Well here is my to cents. I had the exact same plane and it did the stame thing as you are discribing. I spent days on the flying feld trying to make to quit and have a nice slow landing, but know matter what I did it still tryed to stall out on landing. After trying about every thing I could thing of and putting the CG in about every place conceavable me and a few of the guys came to the conclusine that I would just have to bring the plane in hot. It was the only thing I did not like about the plane. I did not try flaps but that might have worked and looking back at it I belive it just might have fixed it but once I got use to bring it in hot it really was not that bad. Just give it a little down to get it about a foot or so off the ground cat power and give a little up and it will make a perfect 3 point landing every time. As far as changeing the CG I set it to where it would fly level inverted and left it there.