F3C and AMA Class I, II, and III Questions

[GM1]

If you have any questions about F3C/AMA contest flying and set up, please feel free to post here. We hope to have some of the very best flyers in the world available to answer your questions.
Gordie

[Gary O]

I'm really interested in this aspect of helis. I like the 3D but my preference is the controlled smooth 3D.

[WayneBrown]

When are you coming to Georgia so I can mooch some lessons?
If I could make sense of the size of the manuvers I might have a chance.

[GM1]

I will be in Birmingham this weekend (May 19-21) for the AAA Classic. I plan on being at IRCHA SE at Mac Hodges in Americus Ga but I do not have the date for that. You're welcome to sneak down to Tallahassee for the weekend sometime and get all the help you want.
Gordie

[cdrking]

Gordie,

I am interested in setting up my Fury (at least in Normal mode) for more precise hovering. I am mainly interested in 3D but have been working on being more precise with everything, including hovering.

I don't really want to change the 3d capabilities but want to be able to do more accurate hovering. Right now the heli seems a bit pitch sensitive in a hover.

I am running an older Fury Extreme with a YS91, 8.45 ratio, SB-16, CP 30%. I'm running 1500 RPM in Normal and 1600 idle up 1 (rarely used) and 1750 in idle up 2.

I run about -20% expo with a Futaba 9Z. I don't really care for flybar weights, I have tried them and took them off. I also run SAB carbon paddles, they weigh the same as the stock MA white paddles (I think). And I am running 710 version II V-blades I believe they are around 185 grams.

Thanks for the input.

Jeff

[GM1]

Hey Jeff,
It's very difficult to have one model that will hover great, do very precision aerobatics, and still do hard core 3D. It's kinda like having a limo that will race F1 but there are a few things you can do to help.
What I have done with a couple of models here is to build a completely new program in the radio with comparatively low AFRs. I think the last R90 I set up I had cyclic AFRs down to 45% in hover and 70% in idle up without changing a thing on the model itself. and it flew pretty well. Flatten out the pitch curve near the hover point in normal to desensitize the collective and you can get the model to sit pretty well and still do reasonable aerobatics.
Now realize that the this model is NOT optimized for F3C style flying but will do OK. The things that make a model good for 3D are most of the time the things we want to change to get the ultimate contest model. For 3D you want massive direct input into the blades and minimum flybar whereas for a contest model we want a massive amount of flybar input and relatively little direct input. For 3D you want a light reactive flybar and light blades for quick response. For contest we want a slow stable flybar with comparatively heavy blades so that it takes some time for a response to occur. 3D models need gear ratios for quick acceleration and quick recovery but not necessarily high speed or rpm. Contest models are loaded and unloaded smoothly so quick recovery is not a design item we need. We want straight line speed, good pulling power, and a dead smooth hover which usually means a much taller gear ratio.
Contest models use very nose heavy stable blades and thicker predictable flybar paddles but 3D models want more tail heavy aggressive blades and thinner more responsive paddles. 3D models may have 10 degrees cyclic when most contest models have max 6 degrees and may not use all of that. Right now my primary model has 5 degrees of cyclic in all idle ups with the capability of overdriving to 6 if I need to for some particular reason.
So while I can take a 3D model and tame it down for better precision, it will never be as precise as a dedicated contest model but since that isn't what you want anyway, try a different radio set up with about 60% throws and see what happens. I let one of our local 3Ders ( he's very good) hover my contest model. He thought the radio quit <g>.
Gordie

[cdrking]

Thanks Gordie,

I'll try your suggestions.

Jeff

[ErichF]

Hey Gordie, Ben, whoever...

I have this new Evo head coming, the new SSZ-III head (all metal). The big changes from the SSZ-II head (std X-Spec) are wider flybar carrier, narrower blade bolt spacing, different mixing arm geometry, and leading blade pitch arms. See the pic below.



Like the SSZ-II head, it's a teetering head assembly, and has fairly wide adjustability. Any ideas on what settings to use for the mixing arms/washout arms and delta spacing? Aside from the teetering head, this new head is a lot like the new Tempest FAI head from MA. Same type of mixing arms and wide flybar carriage. So, I'm open to ideas from you Tempest flyers.

I'll be at B'ham, but I won't have the new head until next week.


Cheers,

Erich

[GM1]

Hey Erich,
I know Wayne has done some work with the Hirobo heads and can give you ballpark figures so I hope he can contribute here but I know he is getting ready to leave for France so it may take a while.
I use 8.5mm of non-correcting delta and keep the flybar ratio as close to 1-1 as I can. On our Tempest FAI rotorhead that's about .9:1. I also use really soft damping as I like to run slower head speeds but it does require that I keep an eye on the dampers as when they are that soft, they tend to wear and the model refuses to "sit" in a hover. I changed them at Alabaster right before the first round and the model was good the whole contest.
Gordie

[ErichF]

Hey Gordie,

I installed the head last night, with all settings at default. I have to run the pitch curves tonight, and I'll establish what the ratio is then. The head with standard setup has correcting Delta, but with an MA arm spacer, I can put the mixers on the other side of the carrier and make it uncorrecting Delta. Do you know the part number for the Spacer you have on your Tempest arms?

I have to order some soft dampers for it, too.

Can't wait to start tweaking this beauty!


Thanks,
Erich

[GM1]

Erich,
Try it at the default settings first and get the feel of it. That way when you change the delta or flybar ratio, you have something to compare it with and you can tell which way stuff needs to go for YOUR particular needs.
Gordie

[Dr.Ben]

Erich,

First, choose whatever holes on the mixers will yield the highest flybar ratio. After you do that, go back and make sure that hasn't cost you your needed collective range.

That head uses bolt on pitch arms. The problem with the way they have them designed is that you either have to add a serious standoff to get the pitch arm pick-off point well to the other side of the centerline of the head or get in contact with Terry Moore and have him machine you up a set of new pitch arms that will allow you to use the head as a trailing arm affair similar to what you saw on Don Wade's model at the AAA contest.

The delta spacer that we use is part number 122-18.

It would be wise to send Wayne a PM so he can give you some delta numbers. Generally, you have to get into the teens (mm's) before the serious benefit of the delta is seen. At that point, the amount of concurrent flybar authority you have will start to dictate how low a head speed the model will tolerate without getting mast bumping in hover or, MUCH worse, blade instability during aeros if the head loads up. The weighted up blades that you noted on Wayne's model are pretty much manditory to keep the head stable when running the amount and flybar and neg delta that he is. My flybar ratio is right at or above 1:1 with as much delta as the head will tolerate without acting stupid if the head gets slow (you could see it wobble at the end of my autos is I was stretching things). I can't use weighted up blades d/t limitations of head construction.

You're going to need to play with that head some, because per Wayne, most of the Hirobo heads exhibit a significant trim change in the wind unless they are given a good transfusion of neg delta +/- some high(er) flybar ratios.

READ THIS:
DO NOT be tempted to crank the delta up really high with a really high flybar ratio withOUT obtaining the appropriate blades. I know of one guy who was trying that a few years back, and Wayne had commented that it was a wonder he didn't blow the head up in flight. This is REALLY fun to experiment with, but do ask questions before you fly if you're uncertain of what you're doing.

Ben Minor

[ErichF]

Hey Guys,

Thanks for the info! I'll start with baby steps and see how she reacts. I'm going to start with the GP-7s I had on at the AAA, but will most likely go to Rotor Tech 710s in the 195-200g range.

This head is pretty versatile. I could flip the grips just as easily as flip the mixers and add a spacer to the arms. First thing's first...gotta make sure it flies ok as is with the default settings. I'm on t he outer hole for the mixing levers, which should be 1:1 ratio...but I have to throw the pitch gauge on and make sure. The mixing levers themselves also have four different positions for the link attachments, so I can achieve some pretty high ratios if need be.

OH, and it looks like I'll make Nashville! Wife n Kid are coming to make it a nice lil family trip. See ya there...


Erich

[GM1]

Hey Erich,
I am not sure RotorTech makes 710s. I use the 720s and I know there are 700s. I'm hoping to get a couple of guys to go to Nashville in class 2 so there can be some serious competition for you. I have some serious practice to do myself if I plan on getting any kind of result at the NATS.
Gordie

[ErichF]

Gordie,

I'll probably go with the 700s, then. I compared the new head with my old, and the grips are about 10mm farther in on the new one. Therefore makes sense to go to 700s from 690s. Since I don't do an auto in my schedule, I'm ok with the slightly higher disc loading anyways. I think it helps in the winds, especially gusty conditions. Anyways, I'll find out how the GP-7s feel this week.

Glad to hear about you doing some recruiting for Nashville! I welcome the challenge. Hopefully Tim is able to get some people in the lower classes, too.

Erich

[Nighttrain]

Erich, I'm running one of these heads stock in a trailing pitch arm, neg delta set up.I'll have to experiment w / more neg delta than stock blade grips. I'll have to cut it back a little at a time, but because of the flybar cage, there is a maximum limit available. See you in Nashville. Doug Trent

[ErichF]

Doug,

I thought about doing that myself, but the offset built into the pitch arms made me think otherwise. Did you use the SSZ-II pitch arms, or did you just compensate for the offset by adjusting the links out? I did what I did essentially to follow the Stratus FAI design, and so far it's working superbly. I'd like to compare our machines in Nashville. Sounds like we are doing the same thing with different geometry.

Cheers,
Erich

[ClayK]

I'm trying to decipher the AMA site, unsuccessfully. How do I get into an event? Where do I find them? I am considering competiting, but I wish it was easier to gather that information off the AMA site. Can someone help?

[ErichF]

Clay, unfortunately, contest season pretty much ends with the Nats. As far as attending one, you just show up like at any funfly, and pay a registration fee. There's an Excel spreadsheet floating around every year that has contest dates and locales. Just ask for it, and someone will send it to you. You can also join the Yahoo Group Competition Heli-List. There's a calendar and files database where you can get all kinds of info. You just have to get a Yahoo User ID. If all you want it digest emails, you don't even need to do that.

There may be one more contest in VA and another in Texas later in the year.

Below is that spreadsheet for 2006, with proposed events. In most cases you can expect the same contests and similar dates for 2007.

Cheers,

Erich

[ClayK]

I can't find the yahoo group, don't suppose you can send me a link?