New build - long distance?

I’ve had one crash because i didn’t set the gyro correctly (silly mistake, i have a switch for rate/heading hold and i forgot it).
I’m just not expirienced with heli’s. It’s on a shelf and ready to fly, but the quad has taken my time. As mentioned, i’ll do some more tests with the quad and take the heli to the field as well so i can practice the flying :slight_smile:

I agree with Pitt that a training gear on a 450 works really good. Just cross a couple fairly stiff sticks (like aluminum arrow shafts) in a X and put some tennis balls on the ends so they can’t dig into the grass and mount it to the landing gear on the helicopter. You can look on the internet and see the training gear that various people have made for their 450’s.

The other thing is, if you have a 450 Pro with a flybar head and it has been crashed and repaired, I would highly recommend taking it to an experienced pilot (like at a RC club) and have him/her check the setup. The flybar and blade tracking needs to be checked. If those aren’t adjusted right you will not be able to fly it. And the setup in your radio needs to be checked to make sure you have the proper throttle/pitch curve, trims and expo set for a beginner pilot.

If that stuff isn’t set right you will be fighting a losing battle trying to learn to fly it. A pro can look at that and take about an hour to set it up right for you to practice hovering.

As Pitt said, once you put a ArduPilot controller on it, it will fly pretty much like a multirotor. But you still need the basic training to use the things that heli’s can do that multi’s can’t, like autorotations. It is a shame to leave that 450 sitting on a shelf. They are the perfect little heli to learn with, and just loads of fun once you master it. My wife learned to fly a heli with the little 500 in the vid. And she crashed it once because I had a beginner setup in it for her, and then I would load my own setup in it for me. I flew it one day and neglected to put her setup back in it. She didn’t know that and took off with it and lost control and crashed it within about 5 seconds. I was told at that point to fix it and do not mess with her heli again :grinning:

Hi Chris,

I"m quite sure the setup is ok. The crash i had was a silly mistake that i’ve learned from as well. I repaired it and have chceked if it still flies the same (it does).

I also need the (safe) space to fly it, i found a good field for that in the area where i also test the drone now. Before, i didn’t have that and i’m just fearfull of a crash and a blade flying somewhere. So - it’s also a safety thing.

I’ve just ordered additional batteries, the drone and the heli currently use the same, so i can go to the field and burn a few batteries!

Is it a flybar model, like a 450 Pro? I suspect it is. And if one of those has been crashed you have go thru the complete head setup bottom to top, re-level it, retrack the flybar and blades and make sure the washout and mixing links are set right. Otherwise a flybar will take off in some unwanted direction on liftoff and be one hairy handful to fly. If you’ve ever heard the old analogy that hovering a heli is like balancing a beachball on top of a basketball, that comes from improperly set up flybar heads :grinning:

On the other hand, if a flybar is set up right they will pretty much hover by themselves, hands-off. And they are very easy to set up with ArduPilot and incredibly stable in Stabilize flight mode - don’t even need to tune the PID’s.

If it is flybarless, that’s a different story. The FBL heads are easy to set up on the mechanical side. Can be a real challenge on the software side.

It’s a flybar. I had to replace and rebuild the head after the crash i had. So, i’ve already done that part.
Tonight i’ll try checking the head again and seeing if the radio and everyhing is still set. Probably change that Gyro mode so i don’t make the same mistake again.

I do have a training gear which worked well.

During hover, it does float around and i have to adjust it for that, but after that it doesn’t drift much by itself. So i think the setup is good enough. I just have to get used to it more and learn to hover more relaxed and also do some nose-in stuff, because i never got to that part :slight_smile:

I haven’t found a local club nearby, otherwise i would seek help there. Especially a setup check wouldn’t be bad.

Yeah, I wanted a RC heli for a long time. I made the mistake of buying a very powerful 700 Nitro with a O.S. 105HZ engine in it as my first heli. Got it used for pretty cheap. It was a no-gyro flybar, ported and polished cylinder, big carb, tuned nitro pipe, almost 7hp - all the good stuff I was told by the previous owner. I figured I could learn to fly it - after all I can fly a multi-rotor really good, and it’s kinda the same, right? :stuck_out_tongue_winking_eye:

So on the maiden flight I was going to practive hovering it. I engaged the clutch and spooled it up, it was really exciting. But no hovering on liftoff. It shot into the air like a Intercontinental Ballistic Missile as soon as I gave it some collective. Whoops - must be something wrong with that throttle/pitch curve I had read about. I had set it to 17 degrees and 100 85 75 85 100 like I had read on HeliFreak. Oh wait - that’s in idleup1, not normal mode. Dang.

The next roughly minute or so of totally uncontrolled flight was some of the wildest 3D stuff anybody has ever seen while I tried to get control of it. Towards the end of the whole experience I remember it going past me about 12 feet away at 50+mph, accelerating like a rocket sled on rails to my right and the tail was pointing left. I pulled the cyclic back and it climbed into a loop and flipped inverted. I panicked and bottomed the collective thinking that would make it come back down. Instead it shot into the sky upside down on a trajectory that looked like it was headed for Europe. How do you get one of these things to come back down, anyhow? I found it about a 1/4 mile away at the crash site.

I loaded up the whole pile of parts and took it to the local RC club and said, “I need help.” The club heli instructor, who has been flying RC heli’s for 35+ years, took me under his wing and taught me how to set it up and fly it. I’ve never looked back. Flying multi’s was never the same again after hanging onto that kind of raw power :smiley:

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Ha, Great story!

I’ve read a lot about modes and my pitch curve is really shallow. Head speed is quite high, as i understand that should make it a bit easier to control.

I might flip the quad to acro mode, as i believe that is a good practice. Crashes with the quad are cheaper than with the T450!

High headspeed makes a flybar more stable. But you can slow it down and add weights to the flybar paddles or flybar rod (regular stainless steel nuts on the flybar rod works nice for weights). That causes the flybar to have greater amount of damping and allows lower headspeed which slows the response time and makes it fly more like a real one instead of a darting snappy 3D demon, which is how they come out of the box.

It was the main reason I put the FBL head on the 500. The flybar wouldn’t fly decent much below 2,500 rpm. With the FBL I can run 1,800 rpm if I want. It doesn’t have much power, but it flies ok at 1,800 rpm. The flybar head wouldn’t.

It’s a 450 Sport V2. That comes with weights at the flybars. They are still on and can be moved inwards for less effect. They are at the far end.

I don’t fully understand the big difference between flybar and FBL. Is there a good article that describes this?

I don’t know about articles. But flybar is what you have. It is a mechanically stabilized head with a Bell-Hiller mixing system on it where the cyclic inputs steer the flybar and the flybar in turn steers the main rotor blades. Since you as the pilot are only controlling the flybar, the flybar has the ability to steer the main rotor independent of your inputs to keep it stable. If, for instance, a wind gust hits the heli and causes it to tip, the flybar automatically compensates for it and levels it back off without you having to do anything.

FBL is the acronym for “flybarless” heads. These are heads with no flybar, the cyclic controls go direct from the swashplate the blade control arms, and the stabilization is done with electronic gyros. In the same instance with the wind gust above, now the electronic gyros sense that the heli has tipped and provide the compensation to re-level and stabilize it. It is an electronic flybar, essentially.

Thanks for explaining that!
I never understood why people invented the Bell-Hiller setup while the FBL setup is so much simpler. This explains it to me!

Back in the times when Bell-Hiller heads were largely used in RC helicopter models, the electronics for emulating those were non-existent.

Before computer radios with mixes in them RC helicopters had very complicated mechanical mixing arrangements on them to do the CCPM mixing, as well. Every once in awhile somebody will bring a vintage Bergen or Hirobo mCPPM heli to the RC club and fly it. They are fascinating. They are big, heavy, either chainsaw or weed whipper engines and properly set up, fly better and more stable than the modern ones.

Then the availability of affordable electronic gyros came along and made multi-rotors and FBL helicopter heads possible.

Totally offtopic now, but ok:
The T-Rex450 still flew nicely. There was actually quite a bit of wind and the quad has made me a bit more comfortable with the heli too. Of the 2200mah battery, i only took it down twice in the hover.

Ordered some more batteries and will try some more. Will then start looking at a pixhawk 2.1 (probably) and seeing if i can mount that on the little thing!

I would think that if you make a custom landing gear like I got on my 500 to give more ground clearance, or make a spacer like it shows in the wiki for heli’s, that you should be able to fit the carrier and PH2.1 underneath. It would likely be an experimental model to see how it works because the Trex 450 just does not have a lot of room to carry decent battery capacity for any long range flights. But 15 minutes should be doable for it to learn how to build a ArduPIlot-flown heli. Then move to 600 class or larger for your long-distance platform. In 600 size it is pretty easy to build a machine that will cruise at 45-50 km/hr, fly for 45 minutes and carry and power all the electronics, along with cameras or other payload.

You’ll have to run the head at 2,700 - 2,900 on the 450 with a flybar so it flies decent. On a 600 you can run as slow as 1,500 rpm and they get considerably more efficient.

Thanks again. I saw the double-bottom and it makes a lot of sense to do it like that.
For the 600’s, what motor/esc and batteries do you run to get that flight time?
Any specific blades you use that are different to create more lift and are less acrobatic?

I would say the eventual design goals to build a VTOL aircraft that meets your need of a 20km range is 45-50 km/hr cruise speed to get the flight done in less than a half hour, and do it on ~110-120 w/kg of aircraft weight. And flight time of 40-45 minutes to allow for wind.

Since you already have a quad with a APM and it flies, try some auto flights with it at say 45 km/hr (13 m/s) cruise in normal winds and use the logs with the current and voltage data provided by the Power Module to determine its cruise efficiency vs weight. That will tell you how far off you are from your design goals, and if it could be scaled up or not.

Those numbers are easily achievable with helicopters. Using a high-efficiency precision wound motor like Scorpion or Xnova and selecting the gearing, system voltage and motor kV to run it at least 85% throttle at 100-120 m/s blade tip speed will get you right in the ballpark. Helicopter motors are not like multi’s where you need to hover on 50% throttle to have “headroom” to make the multi stable. Helicopters use a governor that controls the speed and the load is dependent on pitch. So it’s much easier to optimize the drivetrain in a helicopter for a particular main rotor speed and get peak efficiency from it.

IMO it’s not worth it to try to optimize your 450 because it’s not the ultimate platform you want. Use it to experiment with to get an idea of what you want to do to meet your project goal. There’s way more options for gearing and motors/ESC’s, batteries and voltage once you get into the bigger classes of heli’s. To fly 20km with an electric at those speeds, most likely in wind sometimes gusting to 8-10 m/s, and do it reliably, is no place for a lightweight underpowered aircraft.

The standard symmetrical blades work well for most heli’s. But if you have no need for inverted flight you can look at like asymmetric Spinblades (made in Germany) to further optimize the lift/drag ratio of the main rotor blades running at low blade tip speeds ~100 m/s. Some people will say they tried the asymmetric airfoils and it didn’t make any difference. But they probably tried them at the same speed as symmetric, and it’s not going to make any difference. The asymmetric airfoils create more lift at less pitch and speed, so you have to run them slower to take advantage of what they can do.

I am editing because I did not properly answer this question for you. On my 600 I am using a Scorpion 3226-1400, 1,770 watt motor on 6S power. The gears are 17:1 ratio, 170T main, 10T pinion. The ESC is an Align 75 with a governor, timing set at 5 deg, throttle response medium (easier on the drivetrain in a UAV heli). The batteries are Pulse 35C 6S 5000 mAh - three of them - 333 watt-hour capacity. Blades are Spinblades 610’s, asymmetric airfoil. Headspeed is 1,550.

Note in the video with this same helicopter I was running symmetric airfoils at 1,700 rpm.

Takeoff weight of the heli is 5.4kg with all three batteries onboard (varies with payload), hover power is 610 watts. It can cruise at various speeds pretty efficient, but best cruise is 50km/hr @ 550 watts, no wind. In theory it can fly 36 minutes at that speed, but I set my timer for 28 minutes to allow 8 minutes reserve for wind. So it’s safe range is 23 km at best cruise in wind. It can do more than that on the perfect day with light winds. But those “perfect days” only maybe happen a couple times a year. With an extreme headwind one way (like 35km/hr wind) it is flying at 85km/hr airspeed upwind, which is will outside it’s best efficiency cruise airspeed. The extra power burned upwind at those speeds is not recovered on the downwind leg, so it’s flight time and range is cut short. So it does require some flight planning too, if you are dealing with strong wind :grinning:

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HI Chris,

Many thanks for the extensive responses you’ve given. It shows me that there’s more to just getting a 600 and putting a pixhawk on it with a large battery.
There’s a lot of steps here that I need to get through for this project. That’s ok, it’s hobby (for now) and i have time. Will play around more with the 450 and will keep my eye out for a larger heli at a nice discount!

I really appreciate the responses from you. There’s some great advise! Thanks!

Have fun with it! Unlike many ideas I’ve seen that people want to use autonomous aircraft for, this one is easily doable. Since you have that quad flying I’d do some testing with that too just to get an idea of how far you are from the performance you need to accomplish the task. It’s a matter of power consumption at the cruise speed you need to cover the distance, and how much power you can carry to do it. Just hanging more batteries on doesn’t do the trick.

Airplane will be the most efficient and cover the greatest distance on least power consumed.

Helicopter will be second

Multi-rotor will be last

What makes a helicopter more efficient in cruise is a phenomenon called “Effective Translational Lift” acting in such a way that the advancing blade(s) on the main rotor operate at less pitch and angle of attack than the retreating blade(s) in the cyclic pitch range in forward flight. You can look that up and study it, but it makes both the main and tail rotors more efficient in forward flight than in hover.

You can kill the power on a helicopter in flight, feather the blades and drive them with cyclic pitch,and they are perfectly happy to fly on a pretty nice glide ratio on no power at all in autorotation. With my 600 I can shut it down in flight at 20 meters altitude and fly it in a 360 degree circle on no power and land it as soft as it does under power. That’s because a helicopter actually flies. Kill the power in flight on a multi and it goes down like the proverbial rock.

These are all the reasons why I think if you need a VTOL aircraft with decent cruise performance, the heli is the way to go. :grinning:

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Consider a Quad plane.