The original Neme-Q airfoil was like that also, climbed like a mother with no power. I had to setup a mix to add down elevator to down throttle to be able to land without pushing the elevator stick forward (awkward).

Maybe able to solve your issue with a mix, or switch as well.

The original Neme-Q airfoil was like that also, climbed like a mother with no power. I had to setup a mix to add down elevator to down throttle to be able to land without pushing the elevator stick forward (awkward).

Maybe able to solve your issue with a mix, or switch as well.

Now I am getting confused, earlier in this thread I said I was having to give about 1/8th inch of up elevator at full throttle. Flying at full throttle with the up trim to get it to fly straight would mean it to need some down thrust, correct? Then when I am flying at 1/4 stick or less it pulls up because of the up trim correct? So if I nuetralize the elevator and give some up thrust would that work? So I am getting confused now does it need up thrust or down thrust? I would like to get it to fly straight and level hands off at full power with the elevator at nuetral.

Now I am also wondering after the last to posts if, I should just go fly it and trim it for full throttle straight and level how would she handle at dead stick. During the past races I really ran full out at 10 laps until we were done then we cut the engines to fly them in dead and I did not recall having a problem until I tried to fly around 1/3rd or at 1/2 throttle. Is that the design? no 1/3rd or 1/2 throttle flight capability? Just go "Fast and Turn Left" until your done with 10?


Ed

Ed,

It sounds like up thrust would help your situation. Try adding a 1/32" shim under the bottom of the motor mount. That will give you about 1 degree of up thrust. Report your findings.


Chris

To get it to fly straight and level at full power with no elevator trim yoiu will need to:

1) Make sure that there is no up/down thrust
2) Make sure the balance point is 2 7/8" - 3" back - I like to start at 2 7/8".
3) Fly it staight and level at full power - if you require up elevator then either shim the back of the stab or the front of the wing until the elevator trim in neutral
4) Fly it knife edge and on a 45 degree bank as you would actually spend m ost of your time doing while racing - if the plane tends to creep in toward the center of the course, you may want to add a quarter or two to the tail and revisit 2/3 again.

Repeat 2-4 until it grooves the course in a race attitude

If one wing pushes out consistently during a full elevator turn - add a quarter(s) to the opposite(lighter) wing until both wing tips track through the same vertical plane.

Remember - this is not a sport arobatic plane and flying perfect straight and level is not exactly what you want when racing. There is much written about this by far more accomplished pilots than me. Dub Jett's crap trap series is an excellent place to start.

Good luck.

dan

Thanks for your help Dan, Chris and Dave. I really appreciate it. There are not a lot of guys out where I am that are into Q-500 and the internet makes things so much easier any time of the day to send out a request for help. I will try some of the advice given here and I will let you know how I make out in a few days.

Ed

I see you are in NY... we will have our last 424/428 Q500 race the first saturday of October at PGRC in Bowie MD. Not too far a drive if you want a chance to put it on an actual race course.


Dan

Hi Dan,

I may actually come down there. I am not sure there is also a race that I may go to in Salem CT. on Oct 5th. I may get daring and try to do both but I don't know about that. The sad part of this all is that I am not a total beginner. I have been having some strange things happening with this plane.

FYI - This by the way is the same plane that I raced up in CT. a few weeks ago and I took 1st place in the standard class.

Again I took off, flew the course, did 10 laps and killed the engine and landed. I did not have any trouble then. However there was a heat in where I had to stay up a while while a pilot had some trouble and was trying to land that I did see some quirkyness with the plane at 1/3rd throttle. I re-trimed it a bit only to have some strange issues in the next heat. I had to trim while in a race. So thats when it all began. Then while back on our field I wanted to try letting my son fly, so I went to the 1/2 throttle and then I experienced it again. thats where I am today trying to figure out why this is and all the posts here from me.

Ed

That is your mistake... trying to trim to the throttle position... keep the pedal to the metal and there will be no problems!

Ed, just an idea but check your servo screws. I had an issue with what I thought was a glitch in my elevators the last two times out to do some testing with a back-up plane. What I found over the weekend was a servo mount screw that was loose and was allowing the servo to move under pressure. So it would work fine, then not work right, then come off the corner out of trim. What was happening to me was the servo moving and getting stuck at different angles with the screw threads locking the servo in odd positions after a turn. Until the screw threads finally wore the wood enough for the screw to come out, I had no idea what was wrong.

Check you servos and make sure they are not loose!

Hello All,

As I said I was able to take again the readings and this time I have some Pics. Dan I think I will go with your advice and trim to level flight at full bore, run a mock 10 laps and kill the engine like I do while on the course. I think that will be the way to go . I will try and report back.

Again Thanks to you all for your help.


Ed

why dont you set the degrees to 0 for engine, 2 degrees negative for tail and 0 for main wing. those readings in pics look all over the place especially the engine mount reading.

yup, I have to agree,,, setting the wing to zero is the way to start, then sand the firewall straight and crack off the tail and reset it.

or you could always spend about 25 bucks for some wood and build your self another fuselage and use the same tail you got there.


BV

Except for the tail... everything is pretty close and easy to make perfect... that digital level is "boss". My old fashioned analog "eyeballing" tools are jealous. If you didn't glue the tall on that is a real easy fix. If you glued the tail on... just carefully saw it off and reset... been there done that - only takes about an hour start to finish with a razer saw. Don't even try to go through the glue joint - go just beneath it. Good luck.


dan

Hi All,

Just to clarify the Tail is set at Zero degrees, the Wing has a positive (+0.3) (which is a hair over a 1/4 of a degree of positive incidence and the engine has (-0.4) (slightly less then 1/2 of a degree of down thrust). So with the wing at +0.3 and the engine at -0.4 does'nt that negate each other so there is really (-0.1) degree of down thrust while at full throttle? Then while at dead stick the wing then pulls true with (+0.3) of positive (up) since the engine is out of the picture now, which would help in floating? Am I correct with my calculations?

I have gone back and re-read some threads here including one by Ed Smith. His article he seemed to have some of the same issue's (Adding 14 clicks of Up elevator). I think I will test fly it one more time like I said. Take it up under a mock race condition trimmed for full throttle and fly 10 laps and go high and kill the engine and land.

Also the neat little Craftsman digital level is from Sears (where my wife works) Sears discount for life is twice as nice. They go for about $20.00 when on special sale. They are on sale this week for Sears Craftsman Club members. I am picking up another one. They do conversions, Degrees to angle's as a percent to inch measurements 1/16th , 3/32nd etc. They have tone built in as an option for when your at zero. The work very good. I take 2 Robart bars one on each side of the fuse on the wing and place a striff board or anything flat and stiff across the 2 Robart bars and place the Craftsman level on the board as in the picture. I think they are a little more accurate and a little easier to use then the Robart scale.

Ed

Those look great Ed, I think I will have to pick one up.

Looks like your darned close to 0/0/0.

Trim it for full throttle and race it. You will be fine.

Looks to me like you've got .7 degrees difference between the mount and the wing. You also have .3 degrees between the wing and tail. You should probably take all the readings with the wing at zero. It would make it a little easier to see what's going on. You can us the relative mode on the level to zero to the wing and then take the other two readings.

Hi!
I nearly crasched my Viper this summer due to a weak tail that broke in half. I had lots of up trim 3-4mm and decided to saw away the stab using a japanese razor saw and relocated the stab 3mm down at the leading edge. That removed any up trim problems so now I have just a 0,5-1mm up trim.
I don't have any trim problems what so ever when flying my Viper.
It flies straight as an arrow at full speed and just loses hight when I reduce throttle, just like a normal racer (airplane).
Nelson LS engine is set at 0, Wing at 0 and stab relocated 3mm down at the leading edge.

It could be any # of things that are causing your airplane to re-trim so drastically. First and foremost, I would do what you need to do to lose the elevator trim. Any big "trim" adjustments at the control surfaces may cause trim changes at different speeds.

While most say to put the wing and engine and "zero", and adjust the tail with a bit of negative incidence, I would put the engine and tail at "zero", with some positive in the wing. Here is why. The only thing the tail really does is adjust the angle of attack of the wing. "Up" trim in the tail is pushing down on the tail, to increase the angle of attack on the wing. This scenario actually puts the tail at or closer to "zero", but the wing AND engine with some positive. It also puts the whole fuse in a positive angle of attack. In my opinion, this is more drag than simply having the wing set with some positive incidence, with everything else at zero.

Correct it however you're most comfortable, but you should be better off with the airplane adjusted so that it carries very little trim.

Chris,

I have 89.6 on the firewall if I brought it up 0.4 degrees that would be 90 degrees compared to the Stab which is set at Zero. Keep in mind if I set the stab at zero then if the levl reads 90 degrees thats a perfect right angle to the stab which makes the firewall at Zero degrees as well. But its not at 89.6 it is 0.4 degrees off making it 0.4 degrees of negative thrust on the firewall. The wing is Positive 0.3 degrees. so the win at +0.3 and the firewall at -0.4 that equates out at full throttle to be Zero on the wing and negative -0.1 down thrust. Correct I think so do you guys agree? So I am looking at -0.1 Dn thrust, 0 wing, 0 Stab while under full power so to speak. Correct? Do you guys agree? If so then I am pretty close to Zero across the board under full power. I know that the level is a little hard to read to see from the pictures about the negative and the positive on the firewall, stab and the wing locations.

Ed

compared to the tail you've got 0.4 degrees downthrust, it looks. That doesn't change with throttle setting. Compared to the wing, there's 0.7 degrees down. Where are you coming up with 0.1 degree?

I agree with Fizz. You're trying to justify this out like a math problem. -4 degrees plus .3 degrees plus zero degrees does not equal a good flying plane. All of these angles will create forces that will interact differently over the range of speed the plane goes through.

I also agree with Gary. You need to get the fuse, motor mount and tail to zero, zero, zero, then trim the wing to get it fly straight. The plane will need ~4pounds of lift to fly straight and level. Teh wing needs some angle of attack to make that lift.

Double post...

Hi Guys,

I am glad there are guys out there like you guys willing to help, again I say thanks to you all.

Fizz I was coming up with my number based on that there was Negative 0.4 (almost a 1/2 of degree of down thrust) The wing has Positive 0.3 dgrees (a hair more then 1/4th of a degree of up incidence) I was figuring at full throttle when the engine was making use of the down thrust it kind of negates the tiny bit of Positive wing incidence. Thus leaving -0.1 of down thrust so to speak which gets me close to zero,zero,zero. I know I would prefer to see 0,0,0 across the board on the bench but I was wondering if because of the numbers being the way they are I end up getting there in the long run. Also the Stab is at Zero and glued in. I understand what you guys are saying I just was wondering if I am getting close to the same results with the -0.4 - +0.3 = -0.1

Chris I did not see any article by Bob Bibble on your post, was I suppose too?

Ed

Thanks again guys

Here's an article that Bob Dible (aka HighPlains) wrote about Q500 design and setup:

[link=http://www.modelaircraft.org/MembersOnly/archive/printimage.asp?imagefile=documents/SET1-26/AMA9804/00000095.jpg]Bob Dible Article page 1[/link]

[link=http://www.modelaircraft.org/MembersOnly/archive/printimage.asp?imagefile=documents/SET1-26/AMA9804/00000096.jpg]Bob Dible Article page 2[/link]