Help on the guts for my UAV MPX TwinStar2.

[Red-Rx7]

Howdy all!

My new "fad" is UAV airplanes. I just recently acquired this "Fad" on Sunday evening (1/4/09) by accidently browsing into this section of the forum; which my wife sincerely "thanks" RCGroups for now. :o

Based on non-stop research, I have selected some components for my UAV project. Yet, I need some elder voices of reason to confirm or deny my weird science project. Since I will be investing near $2,000.00 into this project, I want to make sure it at least looks good on paper rather than learning by the ever-so-shrinking dollar.

Project purpose/Goals: The ability to sustain 45 minute flight times, with the option for full autonomous flight via waypoint and active ground telemetry updates; while viewing through First Person.

As with the title, I need some help with the guts (motor, esc, camera, data modems, battery sizes) for the UAV platform I have chosen: Multiplex TwinStar II.

Motor: I want to swap out to brushless to support the additional weight. I attempted to search through the threads on RCGroups by found more than 500 different posts regarding (what seemed to be) more than 300 different combinations of which motors, props, and batteries to use. This is quite discouraging to be honest.

Question: What brushless motor and prop should I use?
I want a balance of efficiency and performance to carry the additional payload. The payload being a pan/tilt mechanism with KX191 camera (~80 grams), Nav System (74 grams), XTend modem & wires (20 grams), 2.4Ghz transmitter (16 grams) + batteries.

This is about 190 grams or 6.8 OZ of gear, without the needed batteries to operate everything.

Would something like this work, or is there better Multiplex Brushless TwinStar2 Motor Upgrade (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXPVG5&P=V)?

ESC: Based on the motor selection above, what AMP rating do I need and which vendor makes the most "trusted" product?

Batteries: I plan on using Lipo's. I haven't split up the electronics yet in my mind (planning on drawing it all out tonight), but I was wanting to keep the battery system separate from the Autopilot stuff and Video & Camera transmitter.

I need to additional research on batteries, for this is one area I am just plain uneducated on. On my helicopters, I run the typical NICAD or NIMH. What would you recommend? Also what size (I assume larger the better)?

Sorry for the noobie based post. I come from a background of flying R/C Helicopters - from large to small (my baby: Vario (http://www.runryder.com/helicopter/t445024p1/)). They all were either Nitro or Gas powered, and I never dabbled into the Electric motor world. So any help would be greatly appreciated. I was hoping to post this in parallel to my research, so I could fully appreciate the information anyone gives.

Thanks,
Mike

[zozie]

Well what you are after is totally doable, tho I'm doubtful you'll get 45 mins flight time with the equipment you'll be hauling. You'll probably need about 8000MAH worth of LIPO packs to achive that but the packs will be heavy.
Your best bet for real time telemetry is to use a radio modem, that way you can also control it from a computer with a joystick very high range line of sight. Also if you incorporate a radio modem, integrating GPS will be a breeze. Any serial or USB GPS receiver will be simple to program even if you are not a programmer. As far as video goes, there is a lot out there you can get for a few hundred bucks, just look in the FPV forum. Ifi you wanna get fancy then you can add a MINI ITX board with a decent CPU. Your plane should be able to haul that as well. From your budget you can definitely make it work. As far as batteries go, try to go 3Cell lipo instead of 2. Just a tiny bit more efficient.

[Red-Rx7]

Thanks for the reply. I have selected all of the UAV equipment I need, just need to figure out the motors, esc's, batteries, and props.

In review of the equipment, the total additional weight is 193 grams. This includes:

- KX191 Camera with pan/tilt hardware
- 2.4 GHz video transmitter
- UAV Navigation system and sensors
- XTend data modem
- OSD video board

In looking at the equipment, I want to run two seperate batteries to power two groups, group "A" being the Camera and Transmitter, while group "B" being the motor/rx/esc/navigation system.

In group "A", I have calculated the power consumption to be about 600mA for active usage. In group "B", I can only factor in the navigation and modem consumption, which is about 330mA under active usage.

Based on these values, I believe something like Lipo 2s 7.4v 2150 MAH (https://www.tanicpacks.com/product_info.php?cPath=111_61_63&products_id=503&osCsid=2dde7b7519bf7f53fb1739a2d5bf89dd) would work. This pack weighs in at 100 grams. I only need 6-12v to power this equipment.

I have no idea how much power consumption the two motors and two esc's would require? So would this battery 3s 11.1V 5000MAH (https://www.tanicpacks.com/product_info.php?cPath=111_78&products_id=586&osCsid=2dde7b7519bf7f53fb1739a2d5bf89dd) work? This battery weighs in at 370 grams.

In calculating the total weight:
- 845g (stock brushed motors, not including ESC, RX, or Battery)
- 193g for the additional UAV equipment.
- 60g for RX / ESC's
- 470g for the two batteries
======
1568 grams, or 55.30 oz, or 3.46 lbs.

In looking at the specs from Tower Hobbies (here (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXKYH2&P=7)), it says that the fully loaded weight is 1500 grams. So I am looking at a "whopping" 68 grams more than the spec weight?

I am not looking for a stunt plane; but I need the power to climb with this weight and handle some mild wind. So which motor, esc, prop would be the best?

Thanks,
Mike

[Connexxion]

Mike,you may want to check this thread first:

http://www.rcgroups.com/forums/showthread.php?t=921899

Abdel

[Gary Mortimer]

Heres a fantastic Twinstar thead http://www.rcgroups.com/forums/showthread.php?t=380793&page=323#post11230593

I used Hacker A20 22L's and for the life of me can't remember the battery as its all back in UK, but 30 minute flight time with main pack easily, I added another battery to power the FPV camera (KX191) plus 500mw transmitter.

I was very very pleased with the Twinstar, Oh I also chucked on my Optio camera as well. It hauled it all around no problem at all.

They need to accelerate a little before climbing, but once you know that.

Bash that Twinstar thread, its all there.

Good luck

G

[spidermurph]

I have fitted this brushless set up to my Twinstar 2, not had chance to fly yet but have read its a good set up!!
http://www.4-max.co.uk/customermodels09.htm