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Question about horizontal stab

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Old 11-25-2016, 01:50 PM
  #1  
Johnnysplits
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Default Question about horizontal stab

1- If the wing is dead level and the horizontal stab is off by a few degrees from being level with the wing, what would happen?
2- If the wing is straight and level, horizontal stab is straight and level with the wing, but the wingtip to horiz stab tip measurement is off a little, what would happen?

Thank you to all who respond!
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Old 11-25-2016, 02:57 PM
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j.duncker
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There would be tiny roll and yaw inputs. If it is a trainer they can be ignored. Less than one click on the trims.

The pattern boys would get a bit uptight about it though.
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Old 11-25-2016, 04:10 PM
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Well, right after take off, it banked to the right pretty hard, had to fight to keep it level as I was trying to trim it. Lost control very quickly before I can straighten it out. This was a Flyzone DHC-2 Beaver.
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Old 11-25-2016, 07:37 PM
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A hard roll on takeoff is usually a tip stall caused taking off too soon or too steeply.

As for your question about the stab, most planes fly properly with some positive decalage. That means the wing's leading edge is up a bit if the stab is level. Some downthrust is nornally required in that setup as well. Twist in the wing and tail are generally a bad thing, but many designs can tolerate it. If your wingtips are twisted up in front, that would make tip stalls more likely.
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Old 11-26-2016, 03:34 AM
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Full power take offs, build speed, tail raises, the whole time correcting heading with rudder, then gently add in up elevator. Once a good rate of climb is established you can reduce power.
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Old 11-26-2016, 04:28 AM
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I did a normal take off roll. It lifted off good, but then it banked to the right almost immediately. I held in a lot of left aileron to try to keep it level as it climbed to about 100 feet. That's when I tried trimming it out, running out of room before it flew over the trees, had to make a left turn, kept adjusting the throttle, trying to trim, then it just got away from me in just a couple of seconds. Pulled off the throttle and watched it go in. There is one thing I remember that might shed some light on this. The night before last, I was showing my girl the nav lights on the plane. I also moved all the control surfaces and bumped the throttle a couple of times. I shut everything down. The next morning, I throw the battery on the charger, load the plane and Tx in the car. Grab the charged battery and head out to where I fly. Unload car, switch on Tx, connect battery to plane. For some reason, it wasn't getting the signal. I had no bind plug with me, so load everything back into the car, go home, grab bind plug and head back to field. Bind the Rx, everything working now. During pre flight, I noticed the ailerons and rudder going in wrong direction. Reversed those two channels, taxi around a bit then took off. Something went wrong somewhere.
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Old 11-26-2016, 04:50 AM
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Jester - Is twist in the wing or tail something that's obvious, or do you need to take 100 measurements to see it?
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Old 11-26-2016, 06:12 AM
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Originally Posted by Johnnysplits View Post
Jester - Is twist in the wing or tail something that's obvious, or do you need to take 100 measurements to see it?

No you do not need to take 100 measurements. In fact of the first two you listed commonly done when marrying up the wing to fuselage on a new airplane I find it easier and more accurate not to mention pleasing to the eye, to do no measuring at all. Instead doing it visually and the trick is simply your eye perspective.

When fitting the wing to fuse I will stand the airplane with the wing in its cradle on the nose aginst a wall and stand back at leas fifteen feet. It now becomes very easy to see even small degrees of misalignment and easy to keep the wing perpendicular to the fuselage. This is that measurement manuals usually have you measuring wing tip to the rear of the fuselage.

The second measurement you listed is wing droop from level when the fuse is level. Agine propping the fuse up level on a bench with wing in the saddle it and backing well to the rear perhaps ten or fifteen feet it is agine easy to see any droop to the wing and it easy to see the same thing when fitting the stabilizer which should always be done after marrying up the wing to fuse.

Now moving on to the last mentioned situation which is twist in a wing. This one is slightly more problematic but yes once agine can be easily spotted if the right visual perspective is used.

This involves propping the fuselage up level on a table and agine a position to the side of the airplane straight out the wing is used a chair is use so you can keep your eye roughly the same level as the airplane. You should now be able to see the airfoil shape of the wing and from your position maybe ten feet away to see any twist in the wing and to see if it is trailing edge up or down. It is necessary to check both sides and compare. Both sides the same is OK. Both sides trailing edges slightly up (wash out) is desirable. Both side slightly down (wash in) is very undesirable. keeping in mind both wings should be the same.

Now having gone through all that I seriously doubt any of it is your problem. It is either a pilot problem i.e. technique or poor control set up throws etc. But I would cast doubt on any radio that just arbitrarily losses its bind. That to me is a serious and not casual problem. I only use Hitec and Futaba systems and that just does not occur.

John
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Old 11-26-2016, 06:36 AM
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Well that would depend on how much twist we are talking about. I recently put together a balsa park flyer that was damaged in shipping. It had about 7 degrees of warp in the wing, which was pretty easy to see. But a Kaos arf from a few years ago had a 1 degree warp in the wing which I only found when I put an incidence gauge on it. You can often see warps in strip aileron wings when you can't get the ailerons aligned on both ends. A 3-4 degree warp could cause the problem you are describing, depending on how much aileron authority it has to counteract the warp. Of course, your ailerons could have been out of trim after the radio issue and reversing the surfaces. That's the main reason I won't ever get caught using Spektrum equipment on anything besides BNF park flyers.

And yes, I know the OP didn't say he was using Spektrum. But I'll bet he was.
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Old 11-26-2016, 06:48 AM
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I'll also take this opportunity to complain about the general lack of quality control on ARF planes. As is nornally the case in mass production, the workers aren't instructed to build it right. They are only told to get it put together. It's amazing how good the ARFs are that come out of China considering the corners they have to cut to keep costs low, but I have yet to receive a plane with truly straight wings or tail surfaces. Half the time, they can't even get a flat sheet stabilizer straight. Those problems are fixable with a covering iron and heat gun, but you do have to be aware of them and capable of making precise enough determinations of the adjustments needed.
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Old 11-26-2016, 07:14 AM
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Yes, I'm using the Spektrum DX6 gen 2 on this plane...and my others. I also have a DX8 gen 2 sitting here that I was going to use on the future big gassers when I get to that point. I also have a Futaba T8J sitting here, but it doesn't have voice, which I really like. Should I sell off any of these rigs? I've also been looking at the Graupner MZ-24 Pro system. I do not want any radio system failures once I get into the giant scale birds if it's possible.
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Old 11-26-2016, 10:44 AM
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In the vast majority of cases using the simple visual technique that I outlined in post #8 will prevent any surprises with any maiden flight on trainers or most sport types. In fact it is what I have done with every airplane some walks up and wants me to do a maiden going back to the sixties. That and my personal assessment of its actual CG and linkage set up, throws etc.

Indeed I share in Jesters hesitation about Spectrum and have personally always avoided it. Have witnessed to many problems since its arrival and everyone locally who have used it almost in every case ends up using at some point in the future futaba or hitec.

Johnny I can tell you little of the Graupner product other than it is a well respected system in Europe. However few are used in this country and that's the rub not only would it be difficult to find others to compare notes with but also I would be concerned with after purchase product support. I actually owned and used an early Graupner system in Germany when I was there in the early sixties but of course that was the Jurasic period in terms of RC radios

Johnny my best suggestion to you for an excellent midrange radio would be something like the 500 hundred dollar Futaba 14SG.

Oh by the way Voice on any radio system one tends to soon tire of. I had the Hitec voice on several of my A9's and of course after the novelty wore off quickly removed the device.

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Old 11-26-2016, 11:14 AM
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Sounds good John. I'll take a look at that Futaba. Thank you.
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Old 11-26-2016, 12:57 PM
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I had a twist in the wing in my lt-40. Inorder to fly level hands off, it needed all the way left sub trim, all the way left normal trim, and some left rudder. The ailerons were straight before takoff and trimming. One aileron was quite a bit up, and the other down, but it flew good.

Lo'ts or radios to choose from. I currently use spektrum, mainly because when I was beginning, it was the most logical choice. Almost everyone in my club uses spektrum, and so it was the easiest to find a buddy box. If I were to choose a new radio right now, I would look at the hitec A9X, or graupner MZ 24. Futaba is nice, but receivers are not exactly cheap.

Hubert
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Old 11-26-2016, 02:00 PM
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Originally Posted by krokodyl View Post
I had a twist in the wing in my lt-40. Inorder to fly level hands off, it needed all the way left sub trim, all the way left normal trim, and some left rudder. The ailerons were straight before takoff and trimming. One aileron was quite a bit up, and the other down, but it flew good.

Lo'ts or radios to choose from. I currently use spektrum, mainly because when I was beginning, it was the most logical choice. Almost everyone in my club uses spektrum, and so it was the easiest to find a buddy box. If I were to choose a new radio right now, I would look at the hitec A9X, or graupner MZ 24. Futaba is nice, but receivers are not exactly cheap.

Hubert
You know what they say, "You get what you pay for". I've never used anything but Futaba and, at the same time, I've never been disappointed with one.
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Old 11-26-2016, 03:28 PM
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Interestingly enough Cheap Receivers, (meaning unauthorized copies by no name factories all around the Pacific Rim) often are the most expensive possible, considering the potential for loss. You would never catch me putting any receiver named after an orange or lemon in anything of mine with sweat equity or cash much over two hundred bucks.

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Old 11-26-2016, 05:08 PM
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Johnny please allow me to point out now the reasons I suggested the 14SG as a step up radio for you now that the cost of receivers has come up. Futabas operating protocol (FASST) has been their standand since day one and is rock solid but recently they added a less expensive system called FHSS. The FASST system remains their high end but the FHSS system rx's are competitively priced. The new 14SG will function with both. Street prices for the SHSS receivers are about the same as Hitecs Optima 7 receivers.

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Old 11-26-2016, 06:22 PM
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Futaba FHSS has been around for years...at least since '07. There's nothing wrong with that system compared to FASST. I'm really looking at the Graupner MZ-24 Pro. It has more stuff than I'll ever use, it talks, vibrates, color screen, aluminum case, lipo battery, 3 receivers, and on and on and on. And it looks awesome!! It has a look like it's a $1000 radio. Do I care if anyone near me has one? No. I can figure out how to use it from the directions and online. I just don't have a plane yet worthy of being operated by that rig.
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Old 11-26-2016, 06:27 PM
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" you get what you pay for " went out the window years ago. There's plenty of good, even great out there that's inexpensive. Big, expensive name brand doesn't mean what it used to years ago.
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Old 11-26-2016, 07:21 PM
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Well now I never suggested that FHSS had anything "wrong" with it compared to FASST only that is it is a less expensive option and only a few of the Futaba transmitters that can use both.

I see I can no longer offer anything so its time for me to bow out of this discussion, I wish you well on whatever choices you make.

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Old 11-26-2016, 08:23 PM
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I didn't mean to get a radio debate started. My apologies to the OP for taking the conversation in that direction.
If I understand you right, the plane was lost. If so, I'm sorry to hear it. Most of us know the frustrations of crashing a plane without a clear explanation why. Your crash could have been caused by warps, a bad linkage, something weird with your trims, a servo problem, or improper setup.

On the radio topic, where did you get your receivers? There are fake Spektrums on the market that are failure prone.
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Old 11-26-2016, 11:43 PM
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Jeeze you guys are no help....newbie with an arf crashes-- and asks a question..the first response was dead on-- on the plank he is flying it wont make a pinch of difference in how it flies... Now maybe the plane got severly warped in the florida heat in the car, the reversed servos were not reversed, something came loose -battery, servo linkage, etc or it was simply way out of trim and the pilot focused on trimming vs flying the airplane and it got away from him. Happens all the time.. the rules are 1) fly the plane..2) fly the plane..3) fly the plane... you guys have turned this in a radio bash.. I would suggest you guys stick to buzzing the pits with your out of control trainers and complaining about the 3d guys vice giving advice..
Johnny- spend your money on another plane and keep practicing.. you already have enough transmitters..
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Old 11-27-2016, 03:58 AM
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Hi!
To answer your questions...
1. It does'nt matter much if the wing is set a little positive to the stabilizer (higher at the leading edge).
2. It does matter! If you have the wing twisted so the tip of the wing is flying at a more positive angle than the rest of the wing that means disaster!!!!! It means that the wing will stall easily and that the plane will turn in that direction.So if you have a plane that at take off immediately turns to the right or snap rolls esily , it means the left wing-tip is warped (twisted wrong, with the leading edge flying at a more positive angle than the trailing edge). All wing tips should be twisted slightly negative, that means that the tip should fly at slightly negative angle than the rest of the wing.
No measurement is needed doing this just heat the plastic film on the wing and twist it slightly!

Last edited by jaka; 11-27-2016 at 04:03 AM.
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Old 11-27-2016, 05:13 AM
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2walla - You are spot on! I'm positive the crash was a novice screw up on my part. It was a $170 learning lesson. I'm still flying the Apprentice with zero incidences. I have ordered another plane that will be here Friday. I will not give up just because of a crash. I will remember next time to just fly the plane and land immediately if there is a problem. I obviously couldn't handle the workload of what was going on during the flight. I'm sure that won't be a problem once I gain more experience.

jaka - Thanks for the input. I will keep my eyes open for wing twist on all future planes.
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Old 11-27-2016, 06:36 AM
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Originally Posted by Johnnysplits View Post
Yes, I'm using the Spektrum DX6 gen 2 on this plane...and my others. I also have a DX8 gen 2 sitting here that I was going to use on the future big gassers when I get to that point. I also have a Futaba T8J sitting here, but it doesn't have voice, which I really like. Should I sell off any of these rigs? I've also been looking at the Graupner MZ-24 Pro system. I do not want any radio system failures once I get into the giant scale birds if it's possible.

Gentlemen note the OP's specific questions in his post #11 above the topic shift was not caused by anyone but the OP himself and it is perfectly reasonable to respond to his questions and concerns.

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