robhoneycutt

I just maidened a H9 Edge over the weekend... powered w/ a 180..

upon take-off it seemed to snap when I gave it elevator..Kind of like when you fly on the simulator w/ too much elevator travel.. only the elevator only has total of 25 degrees or so and I had expo dialed in.

Turning from the downleg @ 500 feet or so, I went into a dive to loose some altitude, and never recovered.. i attempted 3 times to pull up, but each time it simply snap rolled and continued into the ground..



the wing was in one piece on landing , not a scratch, but one aileron servo was stripped, the other one is making a noise when you rotate it.

the elevator halves are together w/ a single yoke style control rod, which seems to be strong and both halves move together well. the servos are futaba 9102's I think..

the engine is fine I think, the fuse is totalled..

Any Ideas on what happened?

Rob

Cheech

My Feedback: (19)

Ouch, that really s-u-c-k-s. My only question would be CG. It would have to be waaaaay out of whack to fly like you described.

robhoneycutt

Mark,

the bad thing is it wasn't my plane[]

I have a new one on the way, but really would like to figure out what happened to make sure it doesn't happen again.. it's pretty frustrating to not know...

Airbike

My Feedback: (6)

One possible clue is how soon did the plane take off? If the plane took off in a really short distance (much shorter than you would expect on a maiden flight), then a tail heavy condition may be present. But I suspect other factors may be at work here.
I maidened my Edge 540 (Lanier 30%) and it was very tail heavy (when rolled inverted and hands off, it would proceed to do outside loops), but I was still able to manage it for a landing. It did not snap when I gave it elevator but was extremely pitch sensitive.
So aft CG would be my first suspect, then?????

Cheech

My Feedback: (19)

So I am still thinking that it could have had a crazy aft CG. But what about that elevator hookup. Was it a single rod, forked to two? I hate those fondue fork looking setuos.

nyrcpilot

My Feedback: (5)

My money is on AFT CG, very AFT cg.


Did you have to ad any weight for balance......did you balance?

Did you put the tank on the cg and forget to compensate?


If I remember right, people were running the batts up front with a saito 1.80, the saito is a very light engine.

RC Havoc

My Feedback: (-1)

Rob, Im actulay having the same problem with my tequila sunrise. Ive tried everything. I used to have an O.S. 61 FX in it, but I couldent get the CG right. I got it as close as I could and ended it flying it with the 61. It flew okay, but It would snap over when I gave it some elevator. At first, i thought it was because the elevator would flex, so I converted to dual elevator servos in the back to add more weight. I flew it again, same problem. I thought maybe its just way to nose heavy. I decided to put my 46 on it intead. (This is the 40 size Tequila Sunrise) I flew it last weekend and it does the same thing. I dont have a whole lot of diflection there, so Im really not sure why its doing this. The only reason I can think of is that one elevator is moving slightly more then the other. It dosnt do it if I give it very little, but when I give it more, it snaps over.

robhoneycutt

thanks for all the replies so far! I appreciate the input from everyone..... the 'fondue' fork in the back of the fuse is still in tact and appears to be sturdy.. while I don't personally like that kind of set up either, it does not appear to be the cultprit. A CG problem is possible, maybe, but unfortunately all I have to go by w/ regards to that is recollection. We added 2-1/2 ounces of weight to the tail to get her to balance,, we balanced her right behind the main spar. it seemed to be fine, but it was a quick field test; not on a balancing stand. I'm not sure if it took off too soon or not.

Rob

Shogun

My Feedback: (2)

In my experience airplanes usually snap for only 2 reasons. First is a very high wing loading and the second is simply having to much elevator throw. I have seen quite a few planes that had VERY small throws do pretty tight maneuvers that upon first impressions the observer would have dismissed the plane even having enough for controlability, much less aerobatics.

25 degrees might not seem like much but with large elevators it can be to much. Something worth trying is to set up the elevator on triple rates and set the lowest rate on the elevator to something VERY low, perhaps only 10 - 15 degrees max. Then if you fly the plane and get into trouble you can pull the switch back and perhaps calm it down enough to land the airplane.

Ronbo

My Feedback: (12)

if you could translate 25 deg of throw into actual inch measurement, it would help. i have the recomended 9/16 for low rate and that is plenty for general flying, with recommended expo dialed in. sounds like too much elevator and a combo of CG too.

the H9 edge is a good flier, but needs to be setup properly per manual.

IMOHO

DMehalko

My Feedback: (42)

If not CG(which it probably is) try running dual elevator servos



david

RysiuM

My Feedback: (1)

Right CG depends on the plane weight very much. Mine H9 Edge is heavy[:@], and the first flight was almost like yours. The difference is, that mine landed in one piece. But it was terrible snappy. The recommended CG is behind 33% MAC. It's fine if wingloading is light. On high wingloading (like mine) with CG around 30% MAC or less it will fly much better. Sorry, no heavy 3D with such weight.
Look at the link, where I put some numbers for H9 Edge.
[link=http://www.rcuniverse.com/forum/m_782157/mpage_2/key_/anchor/tm.htm#782211]http://www.rcuniverse.com/forum/m_782157/mpage_2/key_/anchor/tm.htm#782211[/link]

RysiuM

Cheech

My Feedback: (19)

I'm still guessing that CG was way to aft. The fondue fork servo setuo really blows for a palne that size also - not your fault. Maybe it was just too much elevator, but it still would have been flyable.

The only other thing that hasn't been mentioned is that Futaba 9102 servo you mentioned. That is a really low torque servo to control both halves of the elevator on a big plane. It only has 40oz of torque on 4.8v an 50 oz on 6V. That's just plain not enough for an elevator application.

Geistware

My Feedback: (16)

THis is just an opinion, but I would still go with the thought that you had too much elevator throw. I have only 3/8" on a PW Extra and it is all I use. Most people just laugh when they see the amount of throw that I use. They don't really laugh when I fly!

Columbo

My Feedback: (9)

Even a slightly noseheavy plane with a range of elevator throw (say 20-30 degrees) is especially prone to snapping. How much were you pulling back on the elevator when the plane started to nose dive? There is a natural tendency to pull back on the elevator stick too much in these situations, which would explain why the plane snapped.

Greg

v-snap

My Feedback: (18)

If this is the yellow and blue H-9 models I witnessed the very same thing last year with one model. Two diffrent people brought edges to the field. One flew extremely well while the second would snap with just the slightest inputs on elevator.
The weird part is they started to work though the snappy model by setting things similar to the stable model. CG, Throws, etc were all set as close as possible. Guess what, the plane still flew like crap and was hard to handle. Unfortunatly I don't know what was finally discovered if anything that was leading to the snap tendency. I do know that the throws were cut way down compared to the other model eventually but unsure if it helped the real problem.
v-snap

RysiuM

My Feedback: (1)

Did they have the same engine? What I noticed, the key thing for H9 Edge is weight. 12lb or less - it's very nice and 3D machine. Over 12lb and it flies only scale with very conservative CG and very easy on sticks. Give it more elevator than 1/2 in and it will snap like a crazy warbird.

RysiuM

Jemo

My Feedback: (5)

If you had more than 9/16" of elevator throw(up and down) then it will snap and each time you try to save it, it will do it again.

RysiuM

My Feedback: (1)

Right. Look at the manual (p.42 and p.44). Low rates are for flying. Don't even dare to fly on high rates. On page 44 states:
The elevator high rate is 3in up and 3 in down. It's 6 times of the low rates. No way, you can fly your model using 1/6 of stick movement.

The other challenge is to setup the elevator servo right. Imagine if you ar using 140% travel on high rates, the low rates will be less than 25%. There is no way, you can keep analog servo precise at 25%. See my test on HS-625MG on the elevator:
[link=http://rysium.home.comcast.net/servo.wmv]http://rysium.home.comcast.net/servo.wmv [/link]

RysiuM

Striker

I have the H9 Edge 540 with a ZDZ 50 in the nose. A number of people have bashed this airplane and I was timid when I first flew it with the gasser up front. People said it will fly like crap with a gasser, it will snap and the list continues. It turned out to be one sweet and docile airplane. Before building I did lots of research and found out that the critical thing about building this plane was making the wing incidence is accurate. I have the rudder and two elevator servos (digital) in the tail. If you build the wing as instructions, the incidence will be about 5 degrees off. Lots of people had the plane snapped upon touchdown and I think this was the problem. I had to cut and sand the wing half center to get the wing halves to kiss at 0 degrees dihedral. Dihedral and wing incidence is critical on this bird. You have to use an incidence meter to get this perfectly right. My Edge flies like a dream and it was the first plane I did perfect blenders and the first I ever got to do 6 complete torque rolls. It does most maneuvers really well except harriers and parachutes, neither of which I am a lover for. This Edge is highly sensitive to inputs and I would assume that you may have had too much elevator input with the CG a bit too AFT. My Edge takes off like a cub and lands like a trainer while being a very good aerobatic beast.

If you need any info or building pics email me.

nedyob

My Feedback: (67)

Hello Stricker,
I recently bought a Hanger 9 already built with a OS 1.60 up front and without servo's. This is my second plane of this size I own.
Could you tell me what the throws are for the control surfaces, CG, and modifications you did to tame your Hanger 9 Exge 540.
NEDYOB

Dug89

My son has the H9 Edge w/ an OS160 and it is very snappy. His low rate elevator rate is extremely low. The manual (http://horizon.hobbyshopnow.com/shar...350-manual.pdf) sows low rate deflection at 9/16 inch up and down (total is 1-1/8 inch). It's not a whole lot but it seems to like low throw when running the bird at speed. He also uses a ton (70%) expo on high rate. It will snap on thought at high rate elevator. The low rate throws look inadequate on the ground but they are plenty in the air.

I would be interested on more info from Striker on how to measure and set the wing incidence on this model. Is incidence set to 0 degrees in reference to the horizontal stab? I have never checked this but I can understand how it can be off.

Nedyob, use the recommended CG setting from the manual with the forward most measurment. We had to move the battery to the engine box to get forward CG (rudder servo in the center). It is far easier to land a nose heavy Edge than a tail heavy one. Error on the side of nose heavy and work it back as you get comfortable.

Thanks in advance for the advice

RysiuM

My Feedback: (1)

Sorry, I'm not sure I understand this. Did I get it right?:
You start with recommended forward CG and than go back when you feel like?

The recommended forward CG (4.5 in) is kind of aggressive as a starting point. For this measurement CG points to 35%MAC. I would start rather from 30% MAC which is about 4.0 in from LE.

I guess with minimum target weight 11 lb the instruction might be right, but not many of us got this plane below 12 lb. Mine is 13 lb, and I have learned my lesson - I was flying with CG at 5.0 in. I don't want to do it again.[&o]
I can't understand, how can you fly this plane at 5.25 in which is 40% MAC.

RysiuM

RysiuM

My Feedback: (1)

Striker, On the other post you wrote, that your 14.75 lb Edge is nose heavy. Where is your CG point?

RysiuM

robhoneycutt

Everyone,

thanks for the continued suggestions....it sure is nice to at least try to understand what happens in these crashes so they won't happen again... the new replacement should be here tomorrow ...

Although the throws/rates were 100%,,, I had 100% expo dialed in, and in the plane's death spiral from 500 feet, I had either 3 or 4 attempts at pulling it up....and no matter how gradual or quick I tried to give it elevator, it simply did fast or slow snaps... My friend said that it did snaps to the same direction everytime, but I don't remember that pattern for sure...

Another interesting point is the servos stripped in the ailerons, one completely and the other is close behind it.. w/ the wing in one piece and the ailerons not damaged, could this happen before impact somehow? and could it be part of the cause?

Rob