Qs8005 Helicopter (3.5 channel 42” G.T. Model helicopter ) - Page 7 - RC Groups
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Apr 15, 2012, 09:00 PM
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Hi Rick,
Man, has your luck been bad the past day or so.
I like your antenna idea. That definitely is a very light weight, but simple idea that will be safer for the antenna wire than letting the antenna wire hang. Just make sure the antenna wire isn’t able to touch the lower support rods for the tail boom.
About your 8006 helicopter being quieter, believe it or not, I too have found that the Qs8006 is really quiet for its size, my Qs8006 is about 30 percent quieter flying than my 8005 helicopter. The 8006 main rotor blade noise is very low like a quiet hum and the main gears noise is almost not even noticeable (very quiet and smooth running system). On the 8005, the main blades make more of a louder thaawaupping type noise when flying thru the air (like full size helicopters), and the main gear noise is very noticeable on the 8005. This is one of the interesting things that I noticed about the 8006 when comparing it to the 8005, and I have found many other interesting things that I will post more about as soon as I can.

After shimming the main blades on my new Qs8006, I did fly the 8006 for the 2nd time this evening. There was just a very slight breeze, and the 8006 ran great. I am finding out more interesting stuff about how the 8006 flies and I will post more about it as soon as I can.
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Apr 15, 2012, 09:47 PM
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You have no idea, Ray! I just came in from flying my 9100 since it's still nice and calm... had it up high - at least 60' - and in a stable hover. What I didn't notice was the slight drift it had due to the higher air currents. By the time I got it going and maneuvering back to me it had snuck up behind my neighbors pine tree. He now has an early Christmas light at the very top of the tree....
Apr 15, 2012, 11:28 PM
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Help, I think

Just bought an 8006 and stumbled across this discussion while searching for some answers. Hope I’m in the right discussion.
I should say up front that this is my first rc anything so probably accounts for my problems, well some of them anyway.
Firstly, I read all the posts but could not find the answer I was seeking although one post from letterman7 sounded familiar where he noted "I still have to track down this shake it's had since new".
On my first attempt at flying my 8006, I had gradually increased throttle speed to just below "lift off" speed and I noticed a small vibration from the heli. The top of the rotor drive mechanism did not appear to be running true and looked to be wobbling a bit making slightly concentric circles. But being new, both it and me, I pressed on and increased throttle speed. Bad move, when the dust had settled I found one top rotor blade had sheared in half, the plastic top section of the inner shaft twisted and broken and one arm and balance weight missing from the balance bar.
The eBay seller graciously said he would supply required parts free of charge and I got on the net and bought a heap of spares from China. Maybe they'll turn up one day, maybe not.
The seller’s parts arrived and the 8006 was assembled although during the strip down I did find a few screws that were stripped.
Today not a breath of wind, what else is one to do. Went to a mate’s property, some 200 hectares with vast areas of treeless space. Set everything up, crossed my fingers and eased up the throttle. Up she went, slight rotation, settled that down with trim. Geez it looks small, just how high is that heli? I ease back on the throttle. Again perhaps a bad move, the heli started to rock backwards and forwards, not much, about 50 to 80mm (2" to 3"), did this 3 or 4 times then the balance bar hit the top rotor blade and down it came.
Luckily the canopy makes a good crumple zone as it hit nose first. Canopy shattered, battery holder cracked and a tooth broke off the lower drive gear. Not bad considering the height it fell and these were all parts I had ordered from China, must have known something.
Now I may have pulled back on the throttle too quick and or too far, I don't know, maybe someone here has an idea as to what may have happened. I figure the rocking motion was a precursor to a stall.
A final question if I may. The damage to the top blades which are obviously from the balance bar striking them are much further out that the balance bar reaches, how is this possible? Can the top blades fold up that far?
Anyway, I'm hooked, went and bought another one. Worse case scenario I'll have plenty of spare parts.
Apr 16, 2012, 07:51 AM
Registered User
Welcome Ken! It sounds like your initial power up had issues with the balance bar and/or screws that weren't tight. Oddly, the balance bar will never hit the upper blades due to it's position - it'll take out the lower blades first. Even after "rebuilding" my heli this past weekend, I still have the 'out-of-round' issue with the top blade holder. Everything on my heli is straight and tight (now), but that still remains. I'm putting it off to Chinese quality checks, or lack thereof. It still flies, so until something else catastrophic happens that I have to replace the entire gear case I'll live with it.
For your high flight you've learned how not to ease back on the throttle. These things do tend to have a pendulum effect when they're hovering; if you ease on the throttle too quickly the blades can't support the weight and they bend upwards rather quickly, and the balance bar strikes the lower blades with ugly results as you've witnessed.
You've seen first hand how fragile the blades are. Even a small strike will shatter them. I think I've spent over $100 in the past couple months just on blades alone... it's adding up to be an expensive hobby!

Apr 16, 2012, 10:05 AM
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Hi Rick and thanks for the welcome and the quick response.

With regards to the first attempted flight, all screws were tight. Found that out when disassembling. That one arm simply came out of its mounting I can only put down to a faulty balance bar. The opposite arm which is still attached to the plastic mounting I have placed in a vice and tried with some force to pull it out of the mounting but with no success, it’s rock solid.

With the second flight, the heli was probably some 50 feet up when it started pitching along its longitudinal axis. There was 3 or 4 rather loud clack, clack clacks but all noises including motor noise had ceased before it hit the deck. It just hit the ground and lay their like it had been shot.

The lower blades are in pristine condition but the impact marks left on the upper blades in both instances appear identical. Both have been hit from above and the only thing above them is the balance bar so if the balance bar can't hit them what is causing the damage? The heli was in clear air, no wind at all and the nearest gum tree was over 500 meters away. I've attached a couple of pics of the damaged blades, they may give you a better idea. The pics are a bit rough but they should do.
Rotor-1.jpg is the sheared blade end from the first flight and appears to have been hit only once, the rest of the blade is unmarked. Rotor-2.jpg is the result of the second flight with some 6 strikes to the blade, 2 pretty deep.
Apr 16, 2012, 10:21 AM
Registered User
Ouch! Yeah, the balance bar arms are not supposed to come out - ever. The only way I've pulled those out is to heat the metal rod and slide it out of the mount, which destroys the plastic mount! But I had to see how it was held together. Anyway...
Your blades: those are strikes from the lower blades. Since the two sets spin in opposite directions, it's usually the lower blades that "fold" upwards in a rapid decent or quick turns, and in doing so they interfere with the upper blades and balance bar. By design, the upper blades cannot hit the balance bar - there's just no physical way for that to happen. The bar and blades spin in the same direction at the same speed - they are on the same mount. The clack-clack is the plastic hitting plastic... a very common thing with coaxial heli's I'm finding out. I have yet to sort the gremlins haunting mine this day... hopefully I'll get to it tonight and fix the wiring and be flying again this week and I'll take some video of a 8006 with a lowered blade deck.
Apr 16, 2012, 01:06 PM
Registered User
Hi Ken,
Thanks for posting and your in the right thread. It kind of sounds like your heli may have had a defective rotor shaft or flybar (Balance bar) from the get go. I do have one improbable idea, I wonder if somehow the flybar was defective and broke while flying, and since the main blade are spinning pretty fast, maybe the main blades hit the piece of flybar as it was flying off. But then at the same time I wouldn’t think it possible for the blades to hit the broken piece of flybar 6 times in a split second unless the first blade that hit it made the piece of broken flybar flip up and around in the same spot for a second or so.
Rick is right about the flybar not being able to hit the top blades while flying, and even if it did, even the flybar’s counter weight can’t hit out beyond the last 0 on the 8006 number on the main blade. Your blades show damage way out beyond that point.
Also like Rick was saying, if any blade strikes do occur, on the coaxial helicopters its always due to the lower blades first folding back and then flexing up whenever the throttle is chopped back quick. Unlike what many believe about coaxial helicopters, I can actually shut the throttle off on my 42” Qs8005 helicopter, let it free fall drop a second or two and reapply the throttle and quickly recover with out the blades hitting. To do this safely though, I had to shim the blade holders tighter and I also try to not to have the helicopter rocking too much when chopping the throttle. I haven’t tried this yet with the 8006 since I just received it a couple of days ago and I’m still learning its capabilities.
About you mentioning that the top part of the rotor system was wiggling before takeoff, that definitely was a warning sign that something was badly out of balance, or a rotor shaft was bent, or a flybar weight was coming loose. I have actually flown my Qs8005 several times with a slightly bent rotor shaft’s, and with the blades out of balance, and even one time with a 1” chuck missing from a main blade, but doing that is very hard on the helicopter since it will make the heli shake pretty bad.
I want to mention too that when the rotor system turns on my new Qs8006, (I flew mine twice so far and luckily no flying problems and zero blade hitting so far), everything on the rotor system is turning 100 percent perfectly true and my 8006 helicopter has zero shaking or vibration. So for sure from what I have seen when flying my 8006, it proves that when the 8006’s parts are on right, not bent, or out of balance, the 8006 is actually a super stable and smooth running helicopter.

One tip about learning to fly these helicopter for first time, I have found it is always best to practice takeoffs and landings and learn to hover within 3 feet to 5 feet off the ground with a couple of flights before venturing off with the helicopter. This way you can see and learn what the helicopter is doing, and if you do crash, the damage will be far less. Also, if the helicopter’s main blades are ever about to hit anything solid, whether its in the air or going to hit the ground, always make sure to chop the throttle off before hitting to prevent or limit damage to the main gears, rotor system and blades.

Last edited by Pilot Ray; Apr 16, 2012 at 01:14 PM.
Apr 16, 2012, 01:34 PM
Registered User
Hi Rick,
I can’t believe you got your 9100 stuck in a tree. If you can ever get things worked out on the 8006, maybe on a calm day, you might have to put a string and hook on the 8006 and then fly up and lift the 9100 out of the tree. But then again, if string and hook get stuck on tree, the neighbor would really have a big Christmas ornament in the tree. Oh well, that’s the way things go for me too. So far for me things have been unusually good when flying the 8006 (keeping fingers crossed though).
One thing, I noticed that you say that your 8006 tends to pendulum while hovering. I don’t have that problem with my 8006 (but I have seen it on other peoples You Tube videos), but then after flying my 8005 so much, I do apply the tail rotor power very gradually for a second or two so as to limit over lift of the tail end. If you think tail rotor control seems ok, then I wonder if maybe your 8006’s tail boom length could be the wrong length. If you want me to measure the tail boom length on my 8006, just let me know.

Apr 16, 2012, 02:21 PM
Registered User
Yep, sh*t happens. Oh well... picked up a used 9100 on Fleabay for dirt cheap. I figure I have enough spares to rebuild another, and it's fun to fly, so why not.

The tail boom: why would that make the heli pendulum at hover? The tail rotor isn't moving, so I'm not quite clear what the difference would be if the boom was shorter or longer. I don't think there would be a big discrepancy since the boom supports and horizontal decorative tail all slot/bolt into pre-drilled spots. I think it's just the way this particular model is. I have the same issues as Ken with the upper rotor grips not spinning concentrically (even though the bearings and all are tight and correct), as well as the front to back rock. I haven't statically balanced the thing with the COG directly under the rotor shafts (blades off).. I'll have to try that and see what I get. It would make sense that one end is heavier than the other and the balance bar is simply trying to find trim, hence the rocking. As I said in earlier posts... this thing is more news helicopter than combat helicopter - it's much more at ease just lazily flying about
Under gradual power and moving forward the heli is just fine. Braking to a stop or easing into a stop and hover will always trigger the oscillation.
Apr 16, 2012, 02:30 PM
Registered User
Hi everyone,
I have posted some information below on how to easily shim the main blade pivots on the G.T. Model Qs8006 helicopter (and the Qs8005 helicopter). The shimming of the main blade pivots will help make the main blades fit tighter in the blade holder (blade grip) and will help to remove any excessive up and down play from the blade ends. On my 8006, before the shimming was done, all of the main blades tips each had about ½” of up and down play. After shimming the main blades, the main blade ends now have zero up and down play and it was like giving the lower and upper main blades about a ½” more clearance at the blade tips.

Here is how I made the shims and put the shims on the pivot bushings.
I first started out by using a clear plastic lid from a Walmart cherry pie container (has a thickness of .009 that was a perfect thickness for the shims I needed for my Qs8006) and then I laid the plastic on a flat, hard piece of wood. I then took a hammer and a 7/16” hole punch (can make one out of thin pipe or tubing) and I lightly punched out 4 round pieces of plastic that are 7/16” in diameter. Next I used a common hand held paper punch and punch out ¼” size holes out of the center of each of the round 7/16” plastic pieces. After the shims were punched out, I lightly smoothed out any burrs with a small file by laying each shim one at a time on my finger and lightly filing each side of the shim to remove any high spot burrs (Sand paper can be used in place of file). After cleaning the shims of any burrs, I next slide the plastic shim over the pivot bushing and seated it against the bottom lip of the pivot bushing. (See photo of shim mounted on the pivot bushing below). I then reinstalled the main blades and pivot bushings back onto the helicopter and tightened everything down. Once the blade pivots are tightened, if the plastic shim thickness was the correct size for making bushing shims, the main blades should have just very little to very slight drag on them when they move on the pivot bushing in the blade holder (blade grip). It should be noted that when the shims are installed on the 8006, the shims will be on the underside of the blade holder (blade grips).
Note; when making shims for the Qs8005 pivots, the shims will be slightly different size and have to be made smaller in diameter (3/8“) and the hole for pivot bushing will need to be made just a hair bigger than the bushing. On my Qs8005, it also used a .009 thick shim. When mounted, the shims will be seated against the pivot bushings upper flange so that they will be on top of the blade holders (blade grips) once installed back onto the helicopter.

Apr 16, 2012, 03:13 PM
Registered User
Hi Rick,
I see what your saying since your just hovering when that happens. A shorter tail boom could still make the heli rock easier though since the heli will react faster to any natural air currents while hovering. But I tend to think you could be experiencing the problem I had with my Qs8005 when I lowered the main blades down lower. The thrust started deflecting off the fuselage and canopy (windshield) and shooting forward like reverse thrusters. On the 8006 the body is very close to the lower blades to begin with, and that can make the heli pendulum from thrust deflection towards the front. My 8005 started doing this after I lower the main blade down until I lowered the fuselage down to help. You could try an experiment to rule this out by simply flying your 8006 without the body shell on the helicopter. To do this though, you will have to add some ballast weight to compensate for the fuselage body being removed so the helicopter will balance out properly.
I am baffled though, because my 8006 doesn’t pendulum at all while hovering. In fact, I never even had to adjust the gyro one time since getting it and my 8006 stays pointed exactly straight while hovering without even using the turning joystick to compensate. Having my new Qs8006 fly this well is even strange when compared to my 8005 since my 8005 requires a slight gyro adjustment almost every time I fly it and usually after a few seconds of hovering it generally does need to be compensated a bit with the turning joy stick so as to keep it pointed straight.

Apr 16, 2012, 03:41 PM
Registered User
Chinese quality control at it's finest. I wonder if Ken's is red... seems that the blue models are more stable, even in the videos!
Apr 17, 2012, 04:45 AM
Registered User
Hi again Rick,
In hindsight I'm grateful the first 8006 never got off the ground, I could very easily have ended up with a third eye or worse.

The first 8006 was blue, as is the second which turned up this morning and even though it's dead calm I have resisted the urge to take it straight out for a test flight and am taking a more cautious approach.
I've removed the canopy, balance bar and both sets of rotors. Checked all screws, found a couple not fully seated, screw holding rear rotor loose/stripped as well. Rear LEDs didn't work. This was the result of the 2 pin socket being reversed at the board. A mate's 8006 had the same problem with the rear LEDs and both side LED connectors. Just would not work until the socket (polarity) was reversed. The four red (+) LED wires are now all on the left when looking from the front. As you noted Rick, quality control leaves a bit to be desired.

Decided to do a few bench tests to keep myself amused.
With blades and balance bar removed I put the tacho on it (after running it in a bit).
Speeds selected by LEDs on the controller;
1 Red LED: Upper 2100 RPM - Lower 1540 RPM (repeated) Upper 2150 RPM - Lower 1345RPM
A hell of a difference but probably because this is below take off speed.

2 Red LEDs: Upper 2398 RPM - Lower 2465 RPM

1 Green LED: Upper 2530 RPM - Lower 2570 RPM
I didn't bother with the first two but was able to balance both shafts to 2545 RPM with the trim on the controller. If it works it would beat having to do it in the air.

Max speed: Upper 2675 RPM - Lower 2735 RPM

I then checked the Right/Left controls and found that at the higher RPMs no matter how gently it was applied or how far it was pushed over, if it was held on, the opposite rotor stopped totally. Would seem that turning is a matter of a gentle nudge and release. This seemed to be the case with the tail rotor also, gently, gently, nudge, nudge.

Totally out of boredom I then decided to work out how much centrifugal force was being applied by the balance bar.
One half of the balance bar including rod, weight and 50% of the connector’s weight comes in at 18.72 grams.
I then resorted to my trusty calculator and entered the figures.
Radius - 182mm, Angular speed - 2735 RPM (max speed), Mass - 18.72 grams and hit calculate. Didn't matter how many times I checked, it still came to a staggering 28.4989 kg-force.
It would be like dropping 17 dressed chickens onto the heli. No wonder there is little left after a heavy prang.
Has given me another idea though. Think I'll make up some type of mechanism that allows me to run the tests again but under load and without leaving the ground. Perhaps anchoring via 4 U bolts over the undercarriage. Would allow for take off but only for 25mm or so, also would not allow rolling or tipping.
Apr 17, 2012, 02:40 PM
Different fly 4 different guy
gordonzo's Avatar
Me thinks you guys are having way too much fun with your big coax's.

Come over to the dark side and try a big single rotor like the MJX-F45. You know you want to . . .
Apr 17, 2012, 06:08 PM
I would love to, Gordon.
Can I borrow yours?

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