help for my shopping list?

[Jan Ar]

I am building a blimp for use indoors that are 4 meter long (approx. 13 feet) and would be very happy if anybody could help me with my ”shopping list” for the electronics. I was planning to buy the parts through one of the rc-webshops on the net but have some difficulties in identifying the right parts.

I will have two independently controlled electric motors, one on each side of the gondola.
The two motors (and of course the propellers) must be possible to operate forth and back.

The motors will be connected through a movable axle that can tilt up and down (VT/vectored thrust). I probably will use an aluminium pipe for a stabile axle and impeller propellers for best possible protection of the hull. My shopping list follows. Anybody that can recommend the parts that would be suitable for my use (and where to buy them)?

2 electric 400 motors that can be operated forth and back
2 impeller propellers that fits the motors
2 speed controllers
1 servo to tilt the motors

1 receiver for controlling the servo and the speed controllers/motors
Axle (aluminium pipe or other stabile solution. Should be at least 2 feet long)
Batteries for the receiver
2 accumulator packs for the motors (lightest weight possible)
Radio

I would be very grateful for any help

Best regards,

Jan

[Majortomski]

Jan, I'll save you the time and sell you exactly what you are building. See the picture to the right.

First two rotating motors with fore and aft control will not safely work for a blimp shaped balloon. They do fine if it is a round balloon like a hot air balloon but not an airfoil. The problem manifests itself when you are climbing or decending. With the fans tilted more than 45 degrees up, what was yaw from differential thrust becomes roll, with very little yaw component. Wost case is a vertical climb you have NO yaw or steering control at all.

Aerodynamic flight controls are also very ineffective at slow to no airspeed.

You need a third motor in the tail to control yaw, like a helicopter.

Also a stock 13 foot bag lifts a lot more weight than you think. My whole blimp has an empty weight of 15 pounds, and I still carry 1 to 2 pounds of lead ballast to get to just negative bouancy.

Also your main drive motors do not have to be reverseable. With the neutral position for the fans between 45 and 60 degrees up, your servo rotation should give you about 20 degrees aft thrust at full up. this is enough to back and climb away from a problem and to bring you to a stop in reasonable distance.

And don't forget helium for these is going for $95 a bottle. If you have to deflate each day that's $95 for every day you want to fly. And make sure your flying place has double wide doors.

Good luck, and as I said I have complete new one setting on the shelf ready to ship

Tom