RC Helicopters
Eric Hawkinson, 319 Yellowstone Ave., Billings MT 59101; E-mail: eric@heliproz.com
It's another great month to be enjoying the sport of Radio Control (RC) helicopters! Almost everywhere in the country this is peak flying season. I hope you are all enjoying all the time you get to spend with this great sport and hobby.
I've been getting many letters and E-mails lately. Thank you. My requests for input about what topics to cover got exactly the response I expected, and they were roughly evenly divided among "more flying stuff," "more setup stuff," and "more product stuff." I've been writing long enough to know that you can't please everyone with every column, so I'll keep trying to give some coverage to all three of those areas and a few other things as best I can. From all those I received, the following is an "average" letter from Dave Stafford.
Reader letter
"I'm an avid reader of your column in MA and I noticed your request for input in the latest issue. Having started fixed wing RC back in 1970, I guess I could be classified as an old-timer, but my experience with RC helicopters only goes back five or six years. In that time, I've learned how to fly my entry-level Shuttle ZX in FF, nose-in hover, out-front 360s as well as stall turns (only about 60 degrees nose up, however), horizontal 8s, constant-rate descents to landing, etc.
"Not all that long ago I would've been happy with those skills, but now I'm getting bored. I would like to improve my flying skills, but realize that I must master the proper setup of the so-called Idle Up modes before going much further.
"I'm having a difficult time getting my radio programmed for Idle Up flying. I would prefer that there be no noticeable change when hitting the switch while in a hover. I've accomplished that part of the setup, but run into trouble in the realm of 0 degrees pitch and below.
"The first time I used Idle Up I, the helicopter flew okay until I started a shallow descent, whereupon I experienced a large rotor overspeed and yaw to the left. By the time I got the nose under control and hit the switch back to Normal, the main rotor had been overstressed for maybe 5 seconds or more.
"Now I'm a little intimidated about this realm of flight. Maybe you could shed some light on the ins and outs of the Idle Up modes in one of your future columns.
"Many thanks for your fine efforts! (Shuttle ZX, RD6000 radio, O.S. .32 SX-H, JR 120BB gyro, TT muffler, NHP 550 Razors)"
I like this letter because it gives me a lot of information about equipment and pilot skills and experience. It's much more useful than the E-mails that arrive with something like, "Why can't I get my Raptor to climb inverted?" It seems as though the transition from nonaerobatic flying and hovering to the more advanced aerobatics and 3-D flying is a major sticking point for many pilots. At my shop we get calls every day from pilots who are lost at this stage of the game. So I'm going to rehash prior comments here in hopes that I can take some of the difficulty out of this challenging phase of helicopter flight.
Idle-Up modes
When I first started using "idle-up" modes, I too was uncomfortable with the fact that in Normal mode I hovered at midstick (the old "tradition") and in my idle-up modes I hovered at three-quarters stick. Among other things, it meant that switching into idle-up from the normal mode while in hover was never smooth and precise. I either watched the helicopter drop as the pitch changed from hover pitch to zero pitch or I overcorrected and the helicopter shot up as I advanced the stick to three-quarters when I activated the idle up.
So I changed my setup to allow more consistency in hovering between the various flight modes—and between upright and inverted hovering. The typical V-shaped 3-D throttle curve is the only practical choice for the idle-up flight mode, so I changed my setup in the idle-up mode to have zero pitch at midstick and hover pitch at three-quarters stick. I also changed my throttle-hold pitch curve to have zero pitch at midstick, leaving the top and bottom points alone.
No matter what flight mode is active, I now have midstick as the zero-pitch position in the main blades and hover at approximately three-quarters stick. Whether I'm hovering or in forward flight, I can change flight modes transparently without the helicopter dropping or jumping.
For those uninterested in aerobatics, there is no advantage to this style of setup. In fact, it compresses the throttle/collective response to stick travel from full to full stick, which makes the throttle/collective more sensitive in that region. So if you are mainly interested in precision hovering, it's probably best to stay with the traditional "hover at midstick" setup.
You will need to adjust the throttle curves to match your new pitch curve. If you are used to hovering at midstick and you change to zero pitch at midstick, the throttle setting at midstick must be lowered.
Another advantage of the setup I describe: since all modes are zero pitch at midstick, the throttle setting for that position is the same for all modes. That means you only have to set different head speeds between the different modes.
Setting pitch and throttle curves
- Set the pitch curves first.
- Use a pitch gauge to ensure the pitch settings are exactly what you want for hover and zero-pitch positions. Leave those pitch positions alone once set.
- Adjust the throttle curves to obtain the head speed you want.
- You can measure pitch and head speed, but not engine power directly, so throttle settings require flight testing.
- Full-stick: set the throttle barrel at the wide-open position.
- Idle (low stick): set the carburetor open just far enough to run steadily at low stick and still allow enough servo travel to kill the engine with throttle trim or a kill switch.
- Hover throttle: start around 50% throttle and tune from there. If head speed is too high, reduce throttle opening at hover; if head speed is low, increase throttle.
- At full stick, adjust pitch to match maximum available power.
- If head speed slows at full stick, decrease pitch until head speed stays consistent.
- If the rotor speeds up at full pitch, increase pitch.
Other throttle-setup points:
- Position the throttle arm so that at mid-throttle it is parallel to your throttle servo's output arm. This helps keep throttle response more linear regardless of flying type.
- Make sure the throttle channel endpoints (ATV) are set at maximum and that full stick is at 100% on your throttle curves. This is important because you will likely use cyclic-to-throttle mixes for aerobatics to add power during maneuvers. If endpoints are not maxed, the mix can overdrive the throttle servo.
Radios known to avoid the throttle-mix overdrive issue include:
- JR 10X
- Futaba 92X
- Airtronics Stylus (with helicopter card)
Revo-mix and gyro settings
If you are flying in heading-hold mode (the common setup these days), make sure revo-mix is off or zeroed out completely in all flight modes. If you are flying with a non-heading-hold gyro, you will need a revo-mix. In your 3-D flight mode, a properly set revo-mix will produce the same mix output at full stick as at full low stick if your radio allows midstick to be the zero point for the mix.
Venture Mania?
We have several of the new JR Venture CPs flying, and they are proving to be popular helicopters. Of course, some people can't be happy with any helicopter unless they can squeeze in more horsepower. There are many ways to do this, but the simplest is the way my friend and co-worker Kurt Krieger did it:
- He used the engine mount for the Ergo 46 and drilled the stock Venture fan to fit the shaft (using a drill press).
- He cut a bit off the crankshaft of his O.S. .50, as required by the conversion.
- He installed the long boom and belt from the Ergo 46.
The result: an overpowered, smooth and agile Venture CP 50. With Mavrick 600mm carbon blades the Venture remains smooth and agile, and it climbs and autorotates like a 60-size machine.
Kurt also added:
- A DBC header tank
- Mavrick dual boom supports (to allow access to the plug)
- Some carbon fins
- Venom Racing Temperature Monitor (working nicely)
- Mavrick 50 muffler
Any decent helicopter shop can get you the parts to make this conversion if you are interested. We're still looking for a larger tank that will fit this frame set.
Again, I've overused my space allotment. Until next time, fly safely and happy rotoring! MA
Transcribed from original scans by AI. Minor OCR errors may remain.
