Rotor Concept HPQ1
It is sold worldwide and for far less money via other sources as the LotusRC T380.
Intended for industrial and commercial use as well as for sport use, the HPQ1/T380 is capable of lifting a payload of 12 ounces (340g). Use of the optional three-bladed propellers allow a payload of 1.2 pounds (544g). A camera mount suitable for a small point-and-shoot digital camera is provided, converting the HPQ1 into an exceptionally stable aerial camera platform.
According to Rotor Concept's website, the sophisticated onboard electronics boast an "auto barometer, accelerometer, magnetometer, 3-axis gyro and inertia based (6DOF IMU) self stabilization system." Additional safety features include a low-battery warning system and loss-of-signal failsafe. Triggering either system forces the HPQ1 to gently land itself while emitting a series of beeps to alert the pilot.
Options include various LED-illuminated and non-illuminated automotive-styled bodies and a stand-alone LED lighting system. A six-channel 2.4GHz airplane sport radio is provided, but only four channels are utilized. The quadcopter will operate via any four-channel aircraft radio with a change of receiver.
The transmitter requires eight AA-cell alkaline batteries, not included. The charger jack accepts a standard Futaba charger plug if rechargeable nickel-cadmium batteries are used.
The HPQ1 is sold as a package with the aforementioned radio, a lockable hard shell equipment case, 2200mAh or 2400mAh 3S lithium polymer battery with a Deans Ultra-Plug connector and a DC balancing charger with AC adapter.
Stability is on a par with coaxial helicopters, but unlike most coaxials, the HPQ1 will fly outdoors in light wind. Control in forward flight is similar to guiding a helicopter, but the model will not bank as far as a helicopter will on low rates. It is very forgiving because of its natural stability and can easily be flown by anyone with at least some experience with a coaxial helicopter. Its speed, responsiveness and difficult orientation make it unsuitable for someone with no R/C experience.
Since the HPQ1 is manuevered by offsetting motor speeds, it may "skid" in a turn on low rates with the supplied radio if the airspeed is too fast since the bank and pitch angles are reduced for aerial photography purposes. Reducing the throttle before heading into a turn and/or avoiding excessive forward flight speed will reduce the likelihood of the model simply continuing on its path instead of responding to stick inputs.
The model is far more responsive on high rates, engaged by flipping the channels 1 and 2 toggle switches above the control sticks. Bank and pitch are nearly 45 degrees and the skidding tendency is eliminated.
The Spring RC brand transmitter from Spring Model Electronic Co., Ltd. supplied with the HPQ1 is a fixed-wing sport radio which appears to be a clone of a Futaba unit. Since it is a fixed-wing radio, the throttle stick is ratcheted and tends to cause slightly erratic operation in a hover. A modeler comfortable doing so can easily disable the ratchet, thereby smoothing out the throttle response. It should be noted that the back is sealed with warranty seals.
Users commenting on the HPQ1 at the Ezonemag.com link listed below report erratic operation of the stock radio system, manifesting itself in unwanted bank and yaw during operation, momentary loss of signal and failure of the aileron function to stay in trim. These problems disappear with the use of a quality brand transmitter and receiver. On a computerized radio, setup of the HPQ1 is that of an airplane.
The cost of parts is also an issue when ordered through Rotor Concept. For example, the 3.5mm propeller retainer nuts sell for US$12.99 each through Rotor Concept, but a set of four through Goodluckbuy.com is less than $10.
Care should be taken not to allow the HPQ1 to fly too far from the operator as it becomes difficult to discern the model's orientation.
Propellers and other replacement parts
The propellers used on the HPQ1 are similar to Gaui 8" quadcopter propellers, part number G-210801. They lack the central brass bushing found on the originals. Two are standard rotation, two are reverse rotation. Replacement propellers are available through Rotor Concept, but at US$30.00 for a set of four as opposed to US$9.99 for the Gaui units.
An inexpensive, easily obtainable and excellent alternative is the use of GemFan 8x4.5 quadrotor-specific propellers, available in the US through RCDude.com and worldwide through Goodluckbuy.com. The propellers are well balanced, but require the use of the brass bushing from the original propellers. Cost at RCDude.com is US$2.00 per propeller for the black, carbon filled versions and $1.50 each for colored, fiberglass filled versions.
Another alternative is APC 8x3.8 slow flyer propellers in standard and pusher configuration, available under part numbers LP 08038 and LP 08038SFP and at a cost of US$2.36 and $3.54 respectively. The size, pitch and overall configuration are nearly identical to the originals, but the brass bushings used at the center of the original propellers must be retained. They press into place in the smaller of the two shaft adapters supplied with each propeller.
The online instruction manual recommends that blue liquid threadlocking compound be used to secure the spinner nuts. A loss of a spinner nut will, of course, lead to a crash, but the shaft is an unusual 3.5mm diameter, possibly making it difficult to secure replacement locking nuts. Overtightening the nuts may result in failure of the propellers in flight due to a fractured hub.
A vendor based in Brea, California USA sells genuine LotusRC parts at prices similar to overseas buyers without the risk of dealing with returns and refunds.
- Size: 16.1x16.1x5.5" (410x410x140mm)
- Propellers: LotusRC "8A" and "8B" quadcopter, approximate size 8x3.8
- Motors: Four 980Kv brushless outrunners with removable endbells for storage
- Transmitter: Spring RC TG661A six-channel spread spectrum sport aircraft with digital trims, dual rates and V-tail mixing; the model flies on only four channels
- Receiver: Spring RC six-channel
- ESC: Piggybacked with the onboard electronics, specifications not given
- Construction: Aluminum frame, arms and skid bracket; carbon fiber skids; clear polycarbonate dome; black and yellow shrink wrap tubing used to discern the front and rear
- Battery: Generic 2400mAh 20C 3S lithium polymer with Deans Ultra-Plug connector and JST-XH balancing harness
- Weight: .95 lbs (430g) empty, 1.3 lbs (610g) flight ready, 2.9 lbs (1.3kg) maximum with payload
- Payload: <0.8 lbs (380g)
- Claimed flight time: 18-25 minutes on a 2200mAh battery
- Minimum skill level: Intermediate
- Distributor: Rotor Concept, Inc., 2646 Durfee Avenue, Suite 188, El Monte, California 91732 USA
- Suggested list price (USD): $899.00; can often be found at model shows or electronic shows or as the LotusRC T380 for $299
- Official HPQ1 home page at Rotorconcept.com
- Official Rotor Concept YouTube page
- Ordering and parts page for the LotusRC T380 at Goodluckbuy.com
- GemFan quadcopter propeller page at RCDude.com
- Empire Hobby home page for Gaui propellers
- Gorilla Bob's RC home page for Gaui propellers
- APC page for the standard 8x3.8 propeller
- APC page for the reverse rotation propeller
- Official Spring RC page for the radio system
- Review and photo essay at Diydrones.com
- Review of the HPQ1 at Ezonemag.com
- US-based Ebay parts source