I posted this inquiry on beginners forum but got no response: crashed my Nextar on takeoff [pilot error],fuse. broke off at windshield. After assessing damage came to the following conclusions. Forward fuse. is not constructed strong enough for a "trainer".
Will reconstruct including firewall. C.G.is marked at more than 3 ins. Chord is 10 3/8 ins. According to what I have learned from other posts on this forum the MAC is 25% of the chord,which would be 2.59. Seems that 3inches plus is a bit too far aft for "trainer.
Right thrust is 1 degree, down thrust is 2 degrees.? Way too much steering on ground, caused fatal takeoff.
comments?
not the sharpest tack in the box,but does'nt look right.

I had gotten a Nextstar for my wife to learn on. I flew it a few times and did not like it all that much. The autopilot device fights you when you try to fly it, unplug that thing as fast as you can. This was the first plane that I ever had to use left rudder on takeoff, it has way too much right thrust. I and others in my club could never get the thing trimmed out to fly all that well. This was an arf which was to replaced the Nextstar Select that I broke while showing off for my wife, it had issues from day one. To make a long story short all of the gear from that plane is now to be found in a Sig LT-40.

If you want to reduce the effect of the steering on the ground just move the nose wheel steering link in toward the servo center at the servo end, or out to the furthest hole in the arm at the nose gear itself. I believe that 15 degrees is the norm for nose wheel steering setup, any more than that will cause handling problems on the ground.

MAC is not what you descrbied. It's the whole length of the average chord and the position that the average chord is located at. For non tapered and non swept wings the MAC the aifoil shape that is located at the middle of one panel.

What you described as being at the 25% mark is the neutral point of the airfoil, not the airplane but the airfoil itself. The actual ideal CG range of positions is determined by the wing, stabilizer and tail length all taken together to find the overall aircraft's neutral point and from that a % distance forward of that point to provide an amount of stability that is relative to the use of the airplane. Depending on the size of the tail the CG at the 3 inch point could easily be considered as fully stable enough or it may not be stable enough if the tail is short, stabilizer is small or a combo of both.

Yes, CG should be at 25% MAC of the wing. The tail size can then be minimized for desired stability and carry no aerodynamic loads. That's not to say the plane won't be stable with the CG behind that point, just less so and more sensitive to pitch inputs unless throws are reduced.

As for steering, it doesn't take much and throw should be minimized mechanically ( the outer most hole in the steering arm and inner most hole on the servo arm ).
As for rudder throw on a trainer, I like to set 'em up like this,

At cruise power ( about 1/3 throttle ), the roll rate due to aileron is about 90 deg/s. That is, it takes 4 seconds to roll through 360 deg. Most people might find that slow, but it's quite ideal to start, being well harmonized with elevator response. Then, since trainers have dihedral, they will roll with rudder input. Full rudder deflection should require no more than 1/2 aileron to compensate. This way, if you ever have a problem with the rudder servo going hard over ( maybe from shock from hitting the nose wheel too many times? ), you have enough lateral control to compensate. It's a safety thing...

Thanks for your input.
Seems that the general consensus on this and other forums is that the Nextar is only marginal as a trainer. I bought it as an arf and obtained the readings while beginning the reconstruction. Also noted that the engine was offset 3/8 inch left to compensate for the 1 degree rt. thrust. Measured at firewall. I am curious as to how the "designer"arrived at these parameters,when they deviate so much from the successful formulas put forth in this forum.
Will rebuild with 2 degrees rt. thrust/engine offset appx. 5/32", c.g. closer to center of lift. Should this cause me to put her in the "boneyard", I will have gained $99 worth of knowledge and saved myself further grief from this "airplane".

Only if it's not set up correctly, or there's an actual problem with the structure. The airfoil, moments, and areas are all comparable to a very wide variety of other trainer airplanes. With any one particular model, you will have no trouble finding people who think it's a "bad design", or is "marginal" for its purpose.

If you're trying to teach yourself to fly, then ANY R/C airplane can become "marginal".

If you have problems with your model, you may want to call the support department of its maker.

I've got a student right now who brought a NextStar with an OS46AX on it. He set it up according to the instructions and even had the servo-to-surface rigging connected perfectly. The airplane flies really good and is one of the best trainers I've had the pleasure to fly with a newbie.

It always amazes me when people condemn particular models that are in general use and that are flying well for large numbers of flyers. I've seen a number of NextStars and yet to see one that was giving the owner problems with anything other that engines some of those guys used.

As for the correct CG for any airplane, learn to use something like geistware.com and bypass the generally worthless sound byte wisdom. Heck, learn how often the mfg hasn't a clue.

The Hobbico NexSTAR does not "deviate" from successful design parameters for an R/C trainer aircraft.

The person who designed the Hobbico NexSTAR is a world-class flyer who has moved into model design. The airplane was designed, tested, re-designed, tested, and so on until the objectives of the design were achieved. The airplane was then tested with a wide variety of non-flyers, novice flyers, experienced flyers, and so on before it was put into production. The lead designer had many years of model aircraft design experience before he was chosen to lead the NexSTAR design project. The NexSTAR was in development for a few years before it went into production for general release.

Again, if the model doesn't fly the way you want it to, you may not have it set up correctly, may be trying to fly it outside of its intended flight parameters, or there may be an actual difficulty with the construction of your particular model. It's not in the design of the aircraft.

Greetings Bax,
Didn't intend to trash the Nextar designer,just never have seen a 46 engine placed nearly 3/8 inch off center,much less with 1 degree offset,also travels to the right on engine run out for take off. I suspect the mfgr. lost something in translation. Plugged this plane into simulator and it flys beautifully with modifications.Will admit it also flys just as well without mods. This is why I believe something was lost in translation. Seems as though so many negative comments may not have been brought to hobbico's att.
Your points well taken,feel better about design,
thanks,Fredsedno

>>> It always amazes me when people condemn particular models that are in general use and that are flying well for large numbers >>> of flyers. I've seen a number of NextStars and yet to see one that was giving the owner problems with anything other that >>> engines some of those guys used.

You haven't been to our field to see the Nexstars that have crashed there. I have personally purchased 1 used Nexstar and 2 New Nexstar ARFS and crashed every one of them on takeoff.
In the brief time that I owned a Nexstar, I had maybe 3 normal takeoffs with the 3 planes cumulative and the rest of the takeoffs were either crashes or near crashes. The plane would be tracking normally down the runway, then turn either hard left or right. If I was lucky, I had airspeed enough to take off after it would turn. If not, I would crash into the crops or fence. After the plane would get in the air, it would fly great. but taking off was an adventure. The last time I flew a Nexstar, it turned right into chainlink fence and beat up the fuse and wing. At that time, I decided it was time to change.
Several members of my club looked at my planes and even flew them and they would have the same results taking off. It wasn't as bad for me as other people though. One day a pilot from another field stopped by and asked if one of us ever owned a Nexstar. I admitted I that I had and he said he had owned 4.
Currently I fly an Easy Sport 40 and have over 20 flights without a problem.

Am I gong to condemn a particular model? No, but after $400 dollars that in my opinion I shouldn't have spent, I won't be very enthusiastic about it either.

I haven't had any problems with Nexstars on takeoff, although I can see what you are talking about. They are more prone to veering off course or dropping a wing while still on the ground. I found the best takeoff method is to hold about 1/2 elevator from the start of the run and it will take off on its own. Get the weight off the nose wheel. Of course, that goes for any plane, really...

Hi Jollycub,
I have rebuilt my Nextstar fuse.& hor. stab. I have beefed up both,and modified engine thrusts&engine offset. Also beefed up nose wheel attachment and located it closer to the ctr. of the firewall. The c.g. of the airplane meas. 31/2",which also happened to be more than 30% mac. Will try flying next week,have my next plane ready---stick!

If there is a design problem with the Nexstar, it would be public knowledge. Or at least it would show up in every Nexstar, since it would be designed into it. Since there are lots of Nexstars flying and flying well, it's a good bet there isn't a design flaw. What's left? Manufacturing errors or owner setup errors. And operator errors.

Not finding an error doesn't prove it didn't exist.

An airplane that turns hard left or hard right on takeoff before it reached "airspeed enough to take off" doesn't have something wrong with it's design. It's aerodynamic design hasn't even gotten the chance to work yet. It either has something wrong with it's gear or radio equipment or operating environment or operator.

Sorry but this thread has degenerated to trashing a proven design.

OK, the subject of this thread is the CG location of the Nexstar.

If you got anything on that topic, have at it.

CG location on the Nexstar.......