Chuckie
Key Veteran
Location: Crofton Maryland, MHA member
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| In idle I if I set the pitch curve like you suggested to a LINEAR – max 10 to a + max 10 (With mid at 0??)
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CORRECT.
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| Unless I’m wrong on my Raptor if mid = 0 pitch I can only get +- 10
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AND
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| And let say that I find a throttle curve with a fat U that give me a good flyable – ¾ to + ¾ and then I still find that when I reach both extremes of the U that the head RPM goes to high, my only choice is to bring down the tops of the U meaning limiting the opening of my carb?
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From what I've seen helping others at my field you can get +-11 or maybe +-11.5 max out of the 30/50 Rapter. One guy took is dremmel and opened up the side frame guides to get more pitch travel.
You can try two other things 1) use longer main blades (but watch out for tail blade interference) and 2) use an after market rotor head (kasama?) but I'm not exactly sure which one. There is nothing you can do in the stock rotor head to get more pitch travel unlike other designs were you can add washers under the ball links.
Other that these two things I agree you might have to limit your throttle curve if you cannot load the rotor at full throttle. However if you are not doing that much inverted flying then why not set the top end to +13? With -8 you can still do a lot.
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| I’m still searching the proper pitch so I can get max rpm from the head during the descent.
-1 would scare me into loosing the head speed if that happen should I go max neg (-ev).
How do I get the rev back up.? Or is it sayonara..
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The 'trick' to doing good autos is not really a trick its just understanding whats going on while doing autos. I'll keep this as simple as I can. Here are some theories or rules to consider.
1) the faster you descend the more blade speed you can get back into the blades. You are using velocity to add energy to the blades (assuming you have good techniques).
2) building air pressure under the disk/rotor speed takes a little time. So don't expect the heli to stop right away when come down fast and pull nose high. Also, the longer you allow air to flow over the blades the more energy you'll build.
3) always try for autos into the wind so you capture wind under the disk and for reason #2. It will take less time for #2.
4) the rotor disk can be considered solid if the pitch is set wrong and the disk can be considered non-existent if the pitch is in the right direction. It all depends on how the model is facing when coming down so you need to think about the angle of the blades relative to the direction the heli falls.
5) blade design, center of gravity, and weight affect how the blades auto and how much energy is left at the end of an auto.
6) you will use energy if you use the rotor disk, for example to roll inverted.
If you stop the helis descent and loose all the blade energy you can use gravity to spin the rotor back up. Like #1 you just allow the air flow over the blades to spin them back up. The faster you descend the more air speed. Considering #2 is helpful as it will take time to build back rotor speed. And if the blades are heavy you need more time to build rotor speed. Heavy blades retain energy longer but take more time to spin back up. Finally #3 is used at the end of the auto to help with landing.
#4,5,6 are for more advanced aerobatic autos.
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| I’m still searching the proper pitch so I can get max rpm from the head during the descent.
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Again, there is no magic pitch. It all depends on how you bring the heli down. I suggest you fly up and out and try for a 45 degree angle of descent. Go up and practice the approach in idle 1 until you can go all the way to landing with no problems. Programming 20 or 30 percent throttle in hold is a great idea for practicing. Come down by applying some amount of negative pitch that gives you a descent rate of 45 degrees. Keep the model level on the way down. With the rudder aim for a point 5 feet past your self (10 feet out) so the helis tail is almost facing you when close to the ground. You can turn the tail at yourself once the heli passes eye level if that helps.
Problems people have when doing this is they drop the nose and try to come down blazing fast. This will make the model come down too fast and over shoot the landing area. When they pull the nose up back to level they don't add more negative pitch to keep the same descent rate so the heli climbs back up and over shoots. Finally, when they pull the nose high for too long the heli could start to fly backwards. You won't get a lot or rotor speed if you pull back hard due to #2.
Finally, a good technique is to fly up and out and be able to fly towards your self. When you think the helis is at the top of the 45 degree line start the descent by reducing pitch, hit hold, keep the tail boom level and rotor disk aileron direction level, adjust the rudder to fly towards yourself and start turning away at 30 feet up. Use pitch to set descent rate. The rotor speed should not change much as you are not using a lot of energy in the descent and the 45 degree down approach is keeping the model moving into the wind maintaining rotor speed. Slow the model down both in forward and down direction by using less negative pitch, adjust the nose a little high to slow the model as well but then level it to keep the 45 degree angle. Don't come down too fast but don't stop coming down. Slow the descent rate between 20 feet up and at eye level and you'll hear the rotor start to slow down but don't worry, apply less negative pitch, you might be at zero or slightly above zero. If the auto looks bad switch out of hold and let the rotor speed come back up before heading back up. Stop any forward or side movement and look for a short hover at 1/2 a foot. Proceed to land with the reminder of the rotor speed. Once on the ground don't drop pitch and let rotor speed bleed off. If you make the mistake and are still in the air dropping pitch will bring the model down hard.
Simple no? Just kidding. This stuff takes time to lean so try a few approaches with power over a few flying days. Let your brain think about your autos between flying days and you'll be surprised when it gets easier. At any time don't risk crashing just get out of a bad auto. Finally, you might find you can't do parts of the auto, say you can't fly nose in or at some angle looking up you loose orientation. The best thing is to stop the autos and practice the things you can't do well.
Boy that was a lot. Hope this helps.
Charles
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