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Old Jan 24, 2007, 04:35 PM
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Flybarless electric Raptor 90...

Those wacky Germans are at it again... Ron Sebastian, one of the very capable "new breed" German pilots, and who was heavily involved in the design, prototyping and early testing of the e620SE electric Raptor, has done this very interesting "one of" Raptor 90 conversion, that is absolutely nothing short of elegant in its simplicity. He got rid of the flybar and instead installed two CSM SL720 gyros, which have some special "tweaks" via the standard PC application. More about that in a minute. Here's some pics:

















What Ron did for the conversion was to simply do a new set of lower frames, a couple of spacers for the skids, and a motor plate. Ron used the big blue Pletti and a specially made 12T pinion, with the 95T main gear. He also used a CC Phx HV 110 controller and two 6s-4900 FP Evo 20 packs, in a 12s configuration. The 100% h/s is around 2200, which he has dialed down to about 2000, and is rock solid. He's using 710mm NHPs and has 10-11 degrees of pitch. Performance was "scary", according to Ron. He's never flown anything with that much power. With that big a disc size, spinning at 2000 rpm and 11 degrees of pitch, it has to be pulling close to 5000W, and without the FB drag, a lot more of those watts are getting to the head.

He's using the standard R90 washout, but he used red Loctite to "glue" it to the main shaft. I think just using it with the standard hub and the guide pins would have the same efect, which is to keep the swash from rotating. The innermost link holes are used on the servo arms. If you look carefully in the 2nd to last picture, you can see that he is using two of the multiplex digital servos to move the pitch arm. With one there was too much "groaning" and the response wasn't "crisp". I'd probably try using a stronger servo, like one of Jeff's Ace 1015s, with 200 oz/in of torque, but Ron says this was an easy "fix" and it is MUCH more responsive.

As you can see in the last couple of pics, he's using three SL720s. One is for the normal tail function, and it drives a 9254. The other two are mounted in each axis for pitch and roll, and have the "tweaks" that he and Colin Mill have been working on. The beauty of this setup is that no CCPM mixer is required, as it uses the standard Raptor mechanical mixing. Colin, I hear, is close to finishing up his new eCCPM mixer, which he will include in a complete package as a direct competitor for the uber-expensive V-Stab system.

Ron said so far he's only had a quick first test. For one thing, the motor is surgig, so he needs to dial down the goernor gain setting. He also needs to fine tune the gyro gains and maybe tweak the PC settings a bit more. I haven't played with the SL720 before, but as I undestand it you can adjust a great many things, with the included PC application. Between Ron and Colin, they've got a pretty optimized set of "tweaks", but these were for Raptor 50s. The tweaks need to be tweaked a bit more for the larger R90. Ron will do take care of this fine tuning this coming weekend.

Before I get a flood of emails and PMs, this conversion is not for sale. It was just something Ron did as a "test bed" for the flybarless setup. He wanted something "sporty" to fly at this year's 3D Masters. I'm not sure if TT is working on a 90-size electric, or not. I'm guessing that if they are, we might see something at next week's Nuremberg show.

Anyway, I will get Ron to post his test results here. I must say, how impressed I am with this "outside-the-box" approach to develop a model of the highest performance, by any measure.

-- Gary
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Last edited by GGoodrum; Jan 24, 2007 at 04:41 PM.
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Old Jan 24, 2007, 05:06 PM
United States, MI, Goodrich
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Speechless!!!!!
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Old Jan 24, 2007, 06:16 PM
volts x amps = watts.
Wheelhaus's Avatar
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holy crap... That's awesome.. If you find any video, PLEASE post it!
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Old Jan 24, 2007, 06:18 PM
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That is awesome !!! wow very nice work
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Old Jan 24, 2007, 06:35 PM
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Newport, NC
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http://www.rcgroups.com/forums/showthread.php?t=500904 for those that don't have a R90.

I've got around 60 flights on the helicopter and so far the SL-720's are awesome.
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Old Jan 24, 2007, 07:01 PM
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Melbourne , Australia
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looks like fun boys
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Old Jan 24, 2007, 10:32 PM
volts x amps = watts.
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I've been following some Runryder threads for the last few months about CSM's virtual flybar. I am hoping I can be one of the first in line, but I have a feeling there's already a huge line to begin with...
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Old Jan 24, 2007, 11:14 PM
by Alary Design
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Mesa, AZ
Joined May 2002
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nice! I suspect he "glued" the washout to the shaft because there may be a chance of it dropping too low and coming "unconnected" with the pins in the head at full negative collective.

I bet it's ultra responsive!
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Old Jan 25, 2007, 12:29 AM
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Los Angeles, CA (UCLA)
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Tell me you're gonna build one. I'll definetly drag myself away form my books to watch you test that! I wonder why he selected that big pletti. I ran mine in my maxi, but found in my setup, the actro 32-4 ran a lot better. The pletti has power, but doesn't seem to cool very well. it gets fairly warm, and just stays warm.

Rhett
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Old Jan 25, 2007, 12:47 AM
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Actually, the swash only moves about half as much as it used to, so "falling out" of the guides is probably not an issue.

Ron said it was extremely quick, even with the gain way down low.

-- Gary
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Old Jan 25, 2007, 01:49 AM
Lorents
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Oslo, Norway
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Very cool!

I guess the glueing of the wash out base is dont to make a swash driver for the flybarless head.
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Old Jan 25, 2007, 07:39 AM
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This is really cool

I can't wait until Colin puts something on the market.
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Old Jan 25, 2007, 09:03 AM
volts x amps = watts.
Wheelhaus's Avatar
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Quote:
Originally Posted by lorents
I guess the glueing of the wash out base is dont to make a swash driver for the flybarless head.
yep.

I think I will either drill two holes on both sides and use grub screws, or cut the pin slot clean through on one side of the washout base and use a bolt, so the whole washout base is a clamp, driver link on the opposite side of the clamping bolt.

The only problem with mikado's swash driver is that it pushes against the pitch links. First, it wears into the plastic guides, and secondly, it creates extra friction. On some head designs, that may facilitate a slightly loose ball link to pop off it's ball...
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Old Jan 25, 2007, 10:07 AM
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I guess I'm having trouble understanding why the washout has to be fixed to the shaft when the existing pins would keep it from rotating. The swash doesn't move up and down as much as it does with the flybar setup, so the washout is not going to "fall out".

The SL720 solution is available now, if you have an external eCCPM mixer. I think you can get the "tweaks" directly from CSM. I have several AP-2000i stabilzers, from www.spartanrc.com, that we use with the FMA CoPilot IR sensor on AP/AV rigs for helping to stabilze hovering. One of the functions included in the AP-2000i is a very good eCCPM mixer. One of these plus two SL720s would do quite nicely I think. Spratan RC is also working on their own programmable gyro, which will be a direct competitor for the SL720 and GY611, and I fully expect we'll see a complete V-Stab - like offering from them as well.

Of course, there is also the option of doing a Raptor with the stock mechanical mixing, like Ron is doing with his R90. I wonder if I could modify my eTitan conversion to still keep the motor up high, in back, but use the mechanical mixing. Food for thought...

-- Gary
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Old Jan 25, 2007, 10:18 AM
volts x amps = watts.
Wheelhaus's Avatar
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It's fixed so it doesn't drop down and sit on top of the swash. without a link connected to the flybar, there's no support.

With the washout fixed, you could eliminate a bit of weight and cut off the alignment pins from the head.
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