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Old Aug 08, 2007, 08:00 AM
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Ed Couch's Avatar
North Richland Hills, Texas USA
Joined Aug 2000
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Airship Aft Thruster (Tail Rotor)

Gents

I have a question on what motor/motors are being used in the community for for the Tail Rotor. I use both brushless and brushed in my vehicles and have mixed emotions on what is the best to use. Last evening I smoke checked both a Eflight 480 and Momba 25 ESC (ouch). I use this combination on a couple of 20 footers and while it works well, its not as responsive as a simple brushed motor and reversable ESC as far as response time. Outdoors in combination with aerodynamic controls it is not a problem but flying indoors I wish the response was at least as good as a brushed unit. What is the world using and what ESCs are you using if using brushless motors for the aft thruster? Also, what ESCs are you using for brushed motors? Another thing is the props themselves, what are you using and what configuration (i.e., back to back dual props, single prop, homemade, etc)? I have not seen much information on these subjects and it might make for an interesting discussion.

I've got to go by tonight and spend another 75 bucks on a new Mambo by Castle to get things going again. The smoke check blew the FETS off the board, smoke everywhere. The motor shows scorch marks on the coils as well. All going back to manufacturer for accessment. I have no idea what happened but I figure the motor shorted and started the cycle of self destruction.

ed
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Old Aug 08, 2007, 03:03 PM
dusty bible = dirty life
Majortomski's Avatar
Oklahoma City OK USA Where fakts still exist even if they are ignored
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Mine used a $9.95 Graupner Speed 400 from HL, and either a RC car or RC boat speed controller. Props were wood 6x3s notched to fit in each other back to back, so they were equally in efficient running either way.
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Old Aug 08, 2007, 03:31 PM
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North Richland Hills, Texas USA
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Tom

That is what I've used on all my 13 and 16 footers and worked well. As you have I've always flown the tail with stacked props but for the larger vehicles I've noticed many configurations and wandering about what and how. I like the thrust of the brushless motor and normally swing 9/6 APC props stacked back to back. Plenty of power both ways but it takes time to stop the outrunners and restart the other direction. I program the speed controllers (25 amp Castle Mambo) for a 100 percent forward and reverse and about 75 percent brake and it works with authority but not at the pace of the brushed ESC's and motors. Just takes a little longer to react to the inputs. ed
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Old Aug 08, 2007, 07:14 PM
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Ed. I recently emailed Walter Scholl at http://www.wes-technik.de/English/controller.htm regarding bi-di ESCs.
They sell the Micro 8-Bi ESC which is custom designed for blimps (2nd from bottom of that page). Walter Scholl stated that he does not recommend brushless motors for blimps since there is not a bidirectional ESC available in this weight/ size class. Having scoured the internet for a suitable ESC I more or less agree with him.
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Old Aug 08, 2007, 08:11 PM
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North Richland Hills, Texas USA
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Zep

What are you using as far as brushed motor and ESC for your balloons? I appreciate the comments by Walter but there is an ESC that give equal forward and reverse to 25 amps available from Castle Creation and it is the Mamba. It can be programmed to give a 100 percent reverse and I have many hours flying the airships in this configuration. I also fly a 16 footer using a similar setup with an EFlight 400 and Mamba so I know they work cause simply put I've been there done that many many times. The response is just not on par with a brushed motor and a Duratrax Intellispeed reversing ESC which changes direction with minimal delay. I appreciate all the comments guys I really do as I learn from each. Lets hear more from everyone as we all will learn a little more about the problems encountered while flying our favorite toys around. ed
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Old Aug 09, 2007, 09:58 AM
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Birmingham, AL
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Ed, I use the Novak Spy in my 11' ship, and it has worked flawlessly. http://www.teamnovak.com/products/esc/spy/index.html

I hate magic smoke. If they could just engineer the smell of whiskey into it, then it'd lessen the sting when we let it out of our components!

Edit: I am currently in search of ample reversing ESC's for main power for my 26' ships, for use with Axi 4130 motors. There's hope with a product from Quark, I am just waiting for a response. Novak has a brushless unit rated for 2-4s lipo, but I will be running 5 or 6s, haven't made up my mind yet. If you guys know of a solution, I'm all ears.
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Old Aug 09, 2007, 11:04 AM
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North Richland Hills, Texas USA
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Greg

Thanks for the info especially on the little reversable ESC. I've been looking for a smaller unit for my 13 footers for the brushed end. Only thing is the cost which is a C note but if its equal right and left power wise and will handle a 6 volt Graupner 400 then it may be worth it.

On the question of power for the 4130 consider carrying a second set of batteries for the tail rotor. It's not that big of deal on something the size of a 26 footer and honestly would simplify the tail rotor wiring. I would consider keeping the battery in the gondola with the ESC. On my two 20 footers I use 2 receivers one forward in gondola and second on lower vertical fin so cable to tail is for power only. I honestly don't know if its worth it but it makes cable runs simpler.

As stated before I'm with Greg waiting to hear more. You folks in Europe are doing well what is everyone using on the other side of the pond?

ed
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Old Aug 09, 2007, 11:33 AM
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Birmingham, AL
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I think I paid about $79 at Tower, so don't let the MSRP fool you. That oughta make you yank the old credit card right out now!

I was planning to do an entirely second system for the tail after reading about you doing that with your 20' in your other thread. Silly question, but are you just running a pair of rx's on the same channel, and using the necessary output for your t/r control? I guess I never considered that there won't be any problems using twin rx's on the same channels for the same project, so long as we keep servo channels properly separated. When you say cable to tail is power only, what are you powering...the rx or the motor? I would think that powering the motor over such a long run would lead to a significant voltage drop?
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Old Aug 09, 2007, 12:51 PM
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North Richland Hills, Texas USA
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Greg

I fly strickly 2.4 gig Spektrum DX7's. The two 7 channel receivers are bound to that transmitter and I've not had any problems to date. The forward receiver handles the thrust vectoring, throttles and any aux channels (i.e., coupon release, emergency line reel, lights, etc.) while the after receiver handles the tail rotor, emergency release valve, and aerodynamic controls (rudder and elevator). There is no direct interface between the two receivers. Some may say its a little expensive but its comfortable for me. The power for the aft receiver is via the Castle Creation Mamba ESC and the forward power depending on ESC can be either a seperate power pack or via the ESC's themselves (2) in the forward gondola if capable. I fly right stick for the aerodynamics (pitch and yaw) and the left stick for throttle and tail thruster. The transmitter mixes the rudder and thruster but I seldom use it as I'm so used to working both sticks its a habit. Once in motion the thruster is seldom used except for very low speeds or accelerated turns. I also set the main pitch thruster control up as an auxiliary (aux 1) mixed to the elevator. Once in forward flight the thruster pitch control can be decoupled (trims positive about 4 degrees decoupled (adjustable)) from the elevator via transmitter switch (flaps) and the airship is flown basically in a conventional aircraft manner. The thruster pitch control is again only needed for slow speed work. Once used to this format I would not have it any other way.
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Old Aug 10, 2007, 08:16 AM
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Birmingham, AL
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Nice....I dig that setup, thanks for the info Ed.
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