T Rex 600 nitro super pro

[Novarossi]

Hey guys I just have a question about my 600 nitro pro. I have it set up to +13 and -13 degrees in idle up mode with my govenor at 100% which is 21,000 rpm for the motor. Now the heli flies amazing and has great response, however when I try to do some 3D maneuvers I find it really bogs down a great deal. I am too afraid to even try a simple tick tock because I am afraid it will lose too much headspeed and come down quick. I just bring her up and do a simple flip from invert back to upright and it bogs down so I have to bring it to mid stick again to gain my head speed back. I am going to fly it this weekend in my backyard and get my bro to film it so maybe you guys can help me out. Another issue is my govenor doesn't kick in until like 55% throttle which is almost lift off. Now I know the govenor should kick in around 30%. I have the O.S 50 hyper running really nice and tight and I just didn't know if you guys have had that same problem or what. Any advice would help me out and I will hopefully post my video after this coming weekend so you guys can see and hear the heli in basic flight. Thanks.

[kcgraves]

Two things come to mind right away. Too much pitch and your over revving the engine. I just put a limiter on my EVO 50 with an OS 50 Hyper and did a lot of research/reading before hand. The sweet spot is about 1900 RPM for an OS 50. I have mine at 1800. Assuming you have 0 pitch at mid stick 13 degrees (26 total) is a lot to be coming down from. Bring it down to +/- 10 or 11. 13 degrees with an over revved engine will bog you down for sure.

[Novarossi]

Well I will go set that up for sure, I will tell you if it goes good this weekend. Thanks graves.

[ticedoff8]

Hey guys I just have a question about my 600 nitro pro. I have it set up to +13 and -13 degrees in idle up mode with my govenor at 100% which is 21,000 rpm for the motor. Now the heli flies amazing and has great response, however when I try to do some 3D maneuvers I find it really bogs down a great deal. I am too afraid to even try a simple tick tock because I am afraid it will lose too much headspeed and come down quick. I just bring her up and do a simple flip from invert back to upright and it bogs down so I have to bring it to mid stick again to gain my head speed back. I am going to fly it this weekend in my backyard and get my bro to film it so maybe you guys can help me out. Another issue is my govenor doesn't kick in until like 55% throttle which is almost lift off. Now I know the govenor should kick in around 30%. I have the O.S 50 hyper running really nice and tight and I just didn't know if you guys have had that same problem or what. Any advice would help me out and I will hopefully post my video after this coming weekend so you guys can see and hear the heli in basic flight. Thanks.
I did a quick online search - the T-Rex 600 has an 8.1:1 main gear ratio.
If you are spinning the motor at 21,000 RPM, the main head is turning at almost 2600 RPM (21,000 divided by 8.1 = 2592).
That can't be good.

I also don't see how +/-13-degrees of pitch can be normal either.

I didn't see anything about the motor you are using. Again, doing a quick online search says the O.S. Max .50 Hyper (a very popular engine for this helicopter) has a "Practical RPM Range: 2,000-20,000 RPM" with its peak power coming at 17,000 RPM. Turning the engine at 21,000 is asking for trouble - and does nothing good.
I will assume that most .50cu to .61cu engines have similar power curves.

If you are using the O.S engine in your T-Rex 600, and you are using a governor, you should be setting it for a main rotor RPM of around 2050 or 2100 RPM (17,000 / 8.1 = 2098) - Not 2600.
Even without a rev-limiter or governor, you should set your throttle curves to give you no more than 2100 rpm (17,000 engine RPM = 100% power output from the motor). Any higher RPM is NOT producing more power - it just wears out the engine faster or causes the engine to destroy itself.

By operating the engine at 21,000 (assuming a typical .50 - .61 engine), as soon as you load the rotor head with a high-G maneuver, there is no power left in the motor to keep the rotor spinning at 2500 RPM and it slows WAY down.

Once you reset your rotor to a slower rotor RPM (2000 - 2100) and you want to check your pitch settings - execute a few high-G maneuvers and check your rotor RPM decay - if it drops off a lot, you might have too much pitch. But, it is also possible the motor isn't tuned right (too rich) or the governor is too slow to react to the collective changes.

[cbflys]

The 600N has a transmission ratio of 8.5:1 (not 8.1:1). So a 17,000 RPM engine speed results in a head speed of around 2000 RPM. I run mine my headspeed at about 2100 RPM in stunt mode - which is about perfect for that machine.

I also have a usable pitch range of about 24 degrees. You have to watch the lower collective end. If you don't use a cyclic ring (mechanical or electronic), the swash may hit the frame with extreme cyclic input.

[ticedoff8]

The 600N has a transmission ratio of 8.5:1 (not 8.1:1). So a 17,000 RPM engine speed results in a head speed of around 2000 RPM. I run mine my headspeed at about 2100 RPM in stunt mode - which is about perfect for that machine.

I also have a usable pitch range of about 24 degrees. You have to watch the lower collective end. If you don't use a cyclic ring (mechanical or electronic), the swash may hit the frame with extreme cyclic input.
Yep - I screwed up: 8.5:1 is the correct main gear ratio.

But, running the OS .50 Hyper at 21,000 RPM is still wrong - that is 1000 RPM over the published "redline" and 4000 RPM past its peak power output.

If 21,000 is accurate, then it still explains why his rotor RPM sags so much in high-G maneuvers. That translates to 2470 RPM on the head.

[Novarossi]

Yea that is great help, I have my engine rpm right where it should be now, and I changed the pitch to be about 20 degrees now. There is a huge difference in performance and no bog at all now, however I do have a concern about my Govenor. The govenor is now kicking in at a little more than half throttle? I was thinking about changing my throttle end points to be a little higher to fix that but won't that bind my servo? I really don't know how to kick my govenor in where it is supposed to be at around 30% instead of like 58%. I t really doesn't have any programmable features besides hitting your set button and running the collective up from the lowest point to the highest and it auto sets. Do any of you have this prob? maybe I should set my throttle curve up a little more as it won't affect anything once my govenor is kicked in anyway. If I make my throttle curve go to like 50% at a lower point in my collective stick it should kick in earlier right? If you have any suggestions I would appreciate it thanks. :cool:

[cbflys]

You need to go through your govenor's calibration procedure. That's how it learns your throttle range. Once you do that, it will kick in where it's supposed to.

[Novarossi]

Yea I did that but it is still kicking in at 58% and I don't understand why, my throttle curves are all normal, and I did it step by step according to the manual and I still wait till pretty much lift off. It is not a huge deal but I would like it to kick in before my pitch is positive you know. Hmm I think I will do that throttle curve trick this weekend. This time I will for sure video tape it and you can see how it is running and give me any input if you would like.

[cbflys]

Which governor are you using?

[Jeff Bulmer]

sounds like the Align gov. I have on the 600 , hate it!!!!! it works, but the ATG is so much better .

My Align will kick in about 30 %, but its a dog for keeping the headspd constant. does this one work off the curves, more like a rev-limiter??

[cbflys]

I've setup my share of Align Govs, all of them work fine.

When you calibrate the gov, you have to be absoutely sure there aren't any mixes enabled that can have an effect on the throttle channel. I also like to have the throttle trim set to where the engine idles, this way the gov will kick in at 25% of the useable range. Finally, make sure the throttle curve is a straight line (linear) from idle at low stick to 100% at high stick.

[heli-cuzz]

sounds like the Align gov. I have on the 600 , hate it!!!!! it works, but the ATG is so much better .

My Align will kick in about 30 %, but its a dog for keeping the headspd constant. does this one work off the curves, more like a rev-limiter??

An improperly tuned engine will cause any gov or limiter to act like a dog resulting with inconsistent headspeeds.

[cbflys]

An improperly tuned engine will cause any gov or limiter to act like a dog resulting with inconsistent headspeeds.

A very good point. As with any gov or limiter, you need to make sure your engine runs good without it enabled.

Fly without it enabled, get your curves dialed in, then enable it. Remember, calibrate it first, then mess with the curves.

[Novarossi]

Yea I am running the Align RCE G600 govenor that came with my 600 nitro super pro. I have kept the throttle curves completely linear and there is no other mixes on when I adjust it, the motor is running perfect and there is no real headspeed inconsistencies. It just doesn't kick in until around 60%. So this weekend I made my throttle curve higher before midstick and it actually came on quicker so I don't have to worry about it kicking in at positive pitch. I just wish I knew why it waits so late when you properly set it up?

[cbflys]

I just wish I knew why it waits so late when you properly set it up?
The Align Gov does drop-out at about 50% throttle. The govenor uses the low / high pulse width values it records during calibration to determine the throttle range - and ultimately the drop-out point. It should take the difference between the high/low values, divided by 2 and use that as the drop-out point. If you say it's dropping out at around 60%, then I'd suspect you just have a small calibration error.

Things to check:
1) Make sure your throttle travel limits are as close to 100% as you can get them. The throttle linkage geometry should be setup to provide full carb actuation (closed to full open) with both end-points at 100% and the throttle trim full down.

2) After verifying #1, re-calibrate your govenor. Place your throttle trim full low when you're calibrating.

If after doing this you still see it engaging at 60%, then I'd get it replaced.

[blax1]

Question --- How does this governor detect the engines RPM, from magnets on the fan, or a hall effect sensor on the back plate of the engine? I know on the AR7100R Rx the back plate sensor must be the correct distance away from the plate to detect the RPM throughout the entire range... Just a thought I'm on a limb here, NO governor experience yet... :)

[Novarossi]

This one uses the magnets on the fan, and I made sure the poles are the right way and checked my distances as well. I would have had a video for you guys but the camera was dead but this wekend FOR SURE!! :D

[ticedoff8]

The Align Gov does drop-out at about 50% throttle. The govenor uses the low / high pulse width values it records during calibration to determine the throttle range - and ultimately the drop-out point. It should take the difference between the high/low values, divided by 2 and use that as the drop-out point. If you say it's dropping out at around 60%, then I'd suspect you just have a small calibration error.

Things to check:
1) Make sure your throttle travel limits are as close to 100% as you can get them. The throttle linkage geometry should be setup to provide full carb actuation (closed to full open) with both end-points at 100% and the throttle trim full down.

2) After verifying #1, re-calibrate your govenor. Place your throttle trim full low when you're calibrating.

If after doing this you still see it engaging at 60%, then I'd get it replaced.
Point #1 is very important. It was covered in RC Heli Mag about 5 months ago. GREAT suggestion for setting up a governor or rev-limiter.
You want your radio to be set to provide as close to 100% throttle servo travel with no sub-trims, trims or servo travel adjustments.
Then set your linkage and throttle arm to get full mechanical travel from full closed (idel cut off) to WOT matched to the servo's 100% travel.
I went one step further: I made sure the angle of the servo arm matched the angle of the throttle arm - 50% travel equals 90-degrees between servo and throttle arm.
This will result in a 1:1 match between the throttle servo position and the throttle opening. So, for example, if the radio displays a 50% throttle opening, you know the throttle is actually opened to 50%.
This also helps debug other problems - like governor engagement. When you say "The governor takes over at 60%" - you KNOW that value is real because you have a 1:1 ratio from servo travel to throttle opening.
Having a 1:1 mechanical linkage also helps the governor provide a smooth and consistent throttle response once it has taken over.

My "gut feeling" is you may have compensated for your throttle linkage non-linearly by adjusting the settings in the radio - that would account for the the governor kicking in or dropping offline at inappropriate settings.

It doesn't sound like you have a problem with the basic engine setup - running at 21,000 RPM for a few flights certainly must have "loosed" everything up - and if you are now running in the 17,000 RPM range you should be getting good fuel flow. If you have a thermal probe or temperature gauge (from your electric days), you might want to check the CHT or exhaust header temp immediately after a rigorous flight - I don't know what your temp should be, but it will change based on your needle setting - too rich=colder and leaner=hotter. Too hot will destroy the engine, but it is relative. I tune until I hit a peak temp, then enrich the needle until I get 20 or 30-degrees cooler.

[ticedoff8]

Question --- How does this governor detect the engines RPM, from magnets on the fan, or a hall effect sensor on the back plate of the engine? I know on the AR7100R Rx the back plate sensor must be the correct distance away from the plate to detect the RPM throughout the entire range... Just a thought I'm on a limb here, NO governor experience yet... :)
The AR7100R senses the connecting rod pin (crankpin) on the back of the crankshaft.
According to the Spektrum web site, the sensor is supposed to mounted in contact with the backplate of the engine. Since the backplate is aluminum and the crankpin is hard steel, this makes it easy to sense the steel crankpin as it passes the magnetic sensor.

The Specktrum AR7100R sensor is different from most other governors / rev-limiters. I would GUESS it is basically a wire wound around a metal core (like a little electromagnet working in reverse), and it generates a voltage / current when the the metal crankpin passes by; whereas, most other governors / rev-limiters use a "Hall Effect Switch" that closes when a strong magnetic field gets close. The AR7100R uses the current spikes to count the RPM.

Most other governors / rev-limiters use the "rare earth" magnets - supper strong. They are typically mounting in the fan / flywheel. They look like little hockey pucks. Each magnet has a "north / south" flat side, so one will be mounted with the N-side facing the pickup and the other magnet will have the S-side facing the pickup. Two magnets are used to maintain flywheel / fan balance. I use just one magnet on my fan - and drilled out material on the "heavy side" to re-balance the fan on my High Point Balancer.

The Hall Effect Switch are designed to sense only one pole of the magnetic field. So, it will close when one of the magnets pass in front of it, but not the other. The governor / rev-limiter puts +5v on one lead of the Hall Effect Switch, and when the switch closes (the magnet gets close) the voltage drops to 0v - and it counts the switch closures.

The distance from the Hall Effect Switch to the magnet is important - it can't be too close or it will rub against the fan / flywheel, but it can't be too far because it won't sense a strong enough magnetic field to close the switch. My GV-1 says 1mm.

BTW: Notice I have a LOT of time on my hands to write long winded explanations for the simplest questions. Still looking for a new job and it's too windy to fly. :(

BTW2: I designed a model helicopter governor back in 1987 / 1988. I still have the prototype in my junk box in the garage.
I used an LED and photo diode to "see" through holes I drilled in the fan. I used a "phased lock loop" to set a desired frequency (main rotor RPM) and used the engine RPM (photo diode pickup) signal to generate a error output from the PPL that would control a throttle servo.
It was all analog and it was a lot of fun. And, it worked, but it wasn't reliable. Thebiggest problem was the photo diode kept getting dirty from the oil and crap. This would cause the RPM to get erratic and it would start to get into WEIRD throttle osolations.

[cbflys]

The Specktrum AR7100R sensor is different from most other governors / rev-limiters. I would GUESS it is basically a wire wound around a metal core (like a little electromagnet working in reverse), and it generates a voltage / current when the the metal crankpin passes by;
Actually, it's a magnetically biased Hall Effect Sensor. It's essentially a Gear Tooth Sensor that's commonly used in automobile Anti-Lock Brake Systems.