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HelicopterScale Model RC Helicopters › eCobra / Swift 16 Build
12-09-2008 11:43 PM  9 years agoPost 161
imnxtc

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BC.Canada

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That tail rotor looks to be the same one as they use on their big 90 nitro and gas powered Predators. It is far and away the best tail rotor I have ever used. Its' machined steel hub means you will never have to fear shedding a tail blade and with the two radial bearings that are complemented with a seperate thrust bearing in each blade grip, makes it super smooth and precise.

I had only previously found that elaborate a tail rotor in some of the rather pricey FAI machines I flew a few uears ago.

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12-11-2008 02:54 AM  9 years agoPost 162
Seaviper

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Central MS

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It's been a hectic last couple days. Wife's karate class ended up with a trip to the ER for a broken ankle.

That being said, I did manage to get the mechs done all except the linkages to the servos.

The Swift 620SE frames are different enough that my usual way of mounting things on the Swift did not apply. So, some thought went into the layout of the components.

Got all the soldering and heat-shrinking done, Eagle Tree mounted and programmed, basic radio programming done, tested the power system and sensors (spun her up on the bench...closed course, professional driver, do not attempt this at home ), etc. Tomorrow I will setup my linkages and go fly. (I hope)

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12-11-2008 06:38 AM  9 years agoPost 163
nrad2000

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USA

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Very Nice!!

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12-11-2008 07:23 PM  9 years agoPost 164
pvande

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FL - USA

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Patrick

I am currently building the same USGC Agusta 109 with Swift mechanics that you did earlier - saw it on your gallery.

Didn't want to get too crazy as this is my first scale model and I don't have the skills/tools to do anything more complex at this time.

What is your experience with this model where you have to work with balsa and will have to end up painting etc. Is it is significanty more complex or just more work? Also do you need any specialized tools (except for the painting)?

Just wondering how far I can jump forward in complexity with my next project... I'm dying to do an Apache and the Approach fuselage looks perfect...

Paul

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12-11-2008 09:05 PM  9 years agoPost 165
Seaviper

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Central MS

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That's hard to answer. I come from a background of building airplanes out of wood, so I have some experience. It is alot of work to some, but I don't consider it work.

Skills other than helicopter flying, assembly, and tuning would be fiberglassing and painting. You could also use iron-on film instead of glass cloth. I always use tried and true mechanics in a scale project. I don't like surprises with my mechs when mating them to a scale body.

Update: today finished the linkages to the servos and am just about ready to test fly the mechs. Day job intervened.

The eLogger is acting up after a firmware upgrade. Have to sort this out later tonight or tomorrow.

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12-12-2008 12:31 AM  9 years agoPost 166
pvande

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FL - USA

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Thanks. It's the painting and fiberglassing that I'm concerned about.

Would be great if you could document that part of the build in detail.

Paul

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12-12-2008 01:52 AM  9 years agoPost 167
BustedWingNut

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palestine texas usa

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Woot!! Woot!!...just ordered my eCobra from "A.E." ...anyone see the UPS man yet?....how'bout now? This is a great thread and I AM LOVIN' IT!!!

Growing OLD is not an option.....growing UP is!!!

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12-13-2008 01:27 AM  9 years agoPost 168
Seaviper

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Central MS

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Congrats BustedWingNut. You will not be disappointed.

Pvande...I will document the finishing once I get the mechs tested and installed. My skills are really for fun-scale stuff.

Update: today I sorted the eLogger issue. After upgrading to the latest firmware release, my eLogger V3 wasn't picking up RPM signals on the "To Motor 1" wire off the brushless RPM sensor. After trying two sensors, I determined that the "Motor 2" wire worked fine for both. Thinking it might be a problem with the eLogger itself, I soldered some plugs on my other eLogger V3 and, after doing the requisite firmware upgrade, same thing. Not a problem really, I just lost all RPM readings unitl I tried the #2 wire. #2 wire works fine. eLogger back online.

So, bottom line, all is good. The 620Se is ready for final pitch settings. After that, it's go fly!

Today I decided to change a couple minor things with cable ties and wire routing. More photos coming tonight or tomorrow evening.

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12-14-2008 12:30 AM  9 years agoPost 169
Seaviper

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Central MS

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Worked too late to fly today, but did some tidying up on wiring, sensors, etc.

The tape holding the receivers, switch, reg, rx batt, and eLogger is 3M VHB. Put some rubber shelving material on the underside of the battery tray also with 3M VHB. Keeps the batt from slipping.

The temp sensors for the motor and ESC are epoxied in place.

All that's left for me to do is setup some pitch curves and launch.
Maybe tomorrow.

Here is a test run on the bench with no blades and a linear throttle curve (haven't programmed the throttle curve but it will be mostly a flat 90%). This was to test the eLogger and sensors, not to determine flight data.

Also went back this evening and soldered the RPM lead to the red motor wire, then heat shrinked it.

eLogger seems to be recording correctly, but my file and recorder firmware versions don't match. File firmware version shows 6.00 while recorder firmware version shows 5.51

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12-14-2008 12:39 AM  9 years agoPost 170
Heli 770

rrProfessor

USA.

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It's looking really good!

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12-14-2008 06:55 PM  9 years agoPost 171
Seaviper

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Central MS

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It Flies !

Got air under the skids today FINALLY! Seems like over the last week Murphy has been all over me.

Anyway, it's windy and rainy today (of course it would be) but I managed to get 3 test hops. Just hover tests really.

The blades are carbon 515's, and I had to drill them out on the drill press for 4mm bolts.

So far, no problems. Vibration is minimal, response is quick. Headspeed at around 1750 or so. Temps were good. Amp draw is good too.

I like to setup my birds for a hands-off hover at mid-stick in normal gyro mode. This time I pretty much just guessed at the rudder servo placement (the pushrod adjustment method is to move the servo mount along the tail). It's a little windy, but with 50% gain each way I could hardly tell the difference between normal and HH mode.
Tail appeared to be real close if not spot on.

This session was on a Flight Power 5s1p 5000, Century 600A+, 9T, Electron 80/100 ESC, RotorTech Carbon 515's, RotorTech Carbon 85mm tail blades.

Throttle Curve: flat 90%, Pitch Curve -3, +5, +9

Disregard the Max values as they are from the spike at motor startup.
I am going to check ESC programming to make sure I have it right.

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12-15-2008 06:23 AM  9 years agoPost 172
BustedWingNut

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palestine texas usa

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Using the Swift 16 and an 80A ESC for this project....I have on hand a 4s 4500 and a 6s 5000 batt. Will either of these work? pro's and con's would be most helpful. Thanks

Growing OLD is not an option.....growing UP is!!!

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12-15-2008 01:59 PM  9 years agoPost 173
Hoverup

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Golden Gulf Coast - USA

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Hands down, use the 6S, properly geared for the low headspeed and your components will love the lower current flow afforded by higher voltage.

Cheers - Boyd
AMA 80393
IRCHA 3355
LSF 853
Major USAF
Retired

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12-15-2008 02:05 PM  9 years agoPost 174
Seaviper

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Central MS

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BustedWingNut...I'd go with the 6S because if all remains the same you'll use less amps for the same power.

I used 5S because it's what I had at the time.

Dang Hoverup you beat me to the punch. I was typing a response when you answered.

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12-15-2008 03:28 PM  9 years agoPost 175
Pistol Pete

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Seffner, FL

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SEAviper...sweet.
Please tell me you have a seaplane having a water body behind the house or at least a heli with pontoons

~~Enjoying the hobby one flight at a time~~

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12-15-2008 05:20 PM  9 years agoPost 176
imnxtc

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BC.Canada

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Using the Swift 16 and an 80A ESC for this project....I have on hand a 4s 4500 and a 6s 5000 batt. Will either of these work? pro's and con's would be most helpful. Thanks
If you can gear the motor properly for a desired head speed, then the bigger battery is always going to be the better choice.

As you did not specify your motro KV rating and the pinion you are using it is hard to say.

For example a 4S/4500 battery geared for use at 1450 head speed may give longer flight times then a 6S5000 geared for a 2200 head speed.

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12-15-2008 09:12 PM  9 years agoPost 177
Seaviper

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Central MS

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Pistol_Pete... I have flown helicopters on floats on this lake. Alot of fun. I do not currently have a float equipped bird though.

More flight testing and tuning today.

Re-adjusted the transmission gear mesh (it was fine, I am anal),
generally checked her over top to bottom, and re-arranged the way the TR servo wires are secured. I'm a big fan of 3M VHB.

I find that the pushrod lengths from bell mixer to swashplate as indicated in the manual are a bit long. The manual says 100mm. I shortened mine a bit to give me a more symetrical pitch range. This bird can easily do -11,+11 if need be. Mine is -9,+3,+13 more or less with swashplate mixing of 60% on each channel.

Pitch curve as of today is -3.5, +6, +9 This will probably be tuned more in the coming test flights.
Throttle is flat 90% in ID1 and ID2. Normal is 0,90,90...etc

Here's some test data from a quick hover and a little forward flight.
Mainly just setting up pitch curves and testing gyro settings.

Just noticed the chart is hardly readable. Anyway, headspeed is right at 1800, pulling about 650-700W in some climbouts with most flying at about 450W, max amps about 40, temps about ambient+20F

Flight weight in pod and boom configuration is 6 1/4 lb or about 2.8 Kg

Here is a better chart from Test Hop 7


Headspeed at ~1800, 25A, 470W more or less.

OK, it's back to the shop for some scale body work on the Cobra.
After a few more test flights I will mate the mechs to the fuse.
Then it's more test flying in that config.

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12-16-2008 08:48 AM  9 years agoPost 178
BustedWingNut

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palestine texas usa

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I appreciate everyones input on the batt. concerns. THANK YOU THANK YOU!! Thinking of needing to put out for another battery wasn't a pretty thought. I suppose making CG with the 6s is probably a mute point, as the weights aren't that much of a difference between these canidates. I'm itching to see how the mechs get fitted AND the painting tips that will follow on this build....."Cobra!...Cobra!....Cobra!

Growing OLD is not an option.....growing UP is!!!

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12-16-2008 08:40 PM  9 years agoPost 179
Seaviper

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Central MS

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More test flying of the mechs today. Have to get the mechs ready before diving back into the woodworking.

Had three problems.

1. Noticed about 1mm vertical play in the shaft components due to what appeared to have been the main gear bearing fully seating itself.

Solution: Move the top collar down. Removed head components and shaft to get stuck top bearing collar loose. Ended up damaging the collar, so I replaced it with one from my Swift16. It's not as beefy, but I am not doing hard 3D either.

2. Transmission gear appeared to be too low now with the drive gear running at the top of or above the transmission gear teeth.

Solution: removed tail, enlarged original 3mm high holes in frame to 5mm high. Re-installed tail and adjusted mesh accordingly. This now puts the transmission housing about 1 mm from the gyro tray.

The final mesh is good. Added some washers to cover the enlarged holes. The washers are 3x10x1 mm and match the ends of the transmission housing exactly.

3. Needed to adjust TR servo mount to zero-out rudder subtrim.
Got the rudder subtrim to ZERO. Close enough for me.
Hover in HH mode and normal mode are really hard to distinguish.
The 401/9254 likes the 85mm carbon tail blades.

My method of connecting the Futaba gyro to the JR receiver. 1/16" 2:1 heat shrink tubing did the job quite well.

Customized the length of cable from the gyro to the RX. Need to do the same for the tail servo.

Changed position of battery temp sensor to the bottom middle of batt.

And here is the data from the test flight 10. Had the timer set at 8 mins.

For test flight 10, the eLogger reported 2957 mAH used, and the TP1010C reported 3111 mAH put back in. That's a difference of 157 mAH. Close enough for government work.

Test Flight 11 was hovering in as close to zero wind as possible.

Also notice the spike at motor start is not there or has been greatly reduced. I think this is the gearing, bearings, and motor breaking in.

My motto (this one's for you Doc)

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12-16-2008 09:39 PM  9 years agoPost 180
Seaviper

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Central MS

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I now consider the mechs ready for the Cobra.

Here's some test data from pretty much continuous fast forward flight (figure eights, ovals, etc) with a few long straight-in appchs to land. This is test flight #12.

After test flight 13, I have decided to up my timer to 10 minutes!
This was a flight consisting of mostly all FF flight in windy conditions.

The next update to the thread will be mech installation into the Cobra.

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HelicopterScale Model RC Helicopters › eCobra / Swift 16 Build
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