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Old Feb 27, 2012, 07:26 AM
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This is an old thread but I am interested in this concept. There is a group out in Connecticut that makes these very small generators.

http://www.dstarengineering.com/

And they make a very small 2kw generator

http://www.dstarengineering.com/pist...r_Sets_2kW.pdf

It runs on diesel, no less. I suspect that a gas powered version would be much smaller.
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Old Feb 27, 2012, 07:46 AM
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Those engines look close to normal, old time model plane gas motors.

That gen-set does not look small or light, is a couple feet across,
100-200 LBS.

Lithium batts are so cheap now, just get a bunch and put in series/parallel
for more endurance. Have them drop off the plane with chutes as they
wear down!
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Old Mar 03, 2012, 05:54 PM
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Quote:
Originally Posted by Hovertime View Post
If you need 2kW of electric power it would have to have about 2.5kW of mechanical power provided TO the generator, and to be on the safe side it will need an engine that has 4kW of power max rating, and run it at 65% of its power. Or get an engine that has rated CONTINUOUS 2.5kW power rating.


As most said-much easier and economical just to use engine to provide 2kW for the props in the first place, skipping all th conversion loss.
And also skipping the extra weight and complexity,cost etc; and more bits means more potential for failure.
I have been involved in several military UAV projects where we took some power off the engine (generator on back end of shaft) to charge batteries, which act as smoothers, to supply avionics, downlinks etc but these were big boys with 40 hp upwards. If you want endurance/range, use diesel; Davis Diesel sell conversion units for a large range of "model" engines.
The downside about engines is altitude effects, guesstimate power loss is about 3% per thousand feet. If you want to go to real altitude, say 12k feet and above then go electric; electric motors don't have to breathe air with oxygen in it! At the end of the day its about; what range/duration, at what height, with what payload .
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Old Mar 07, 2012, 11:00 AM
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What about this small turbine driving the generator? I have a 2.5m Vario XLC heavy lifter helicopter that uses a much larger and thirsty 8 kw turbine. I've considered converting it to a hybrid electric with this smaller PHT2 running the gen. Initially it will be close in weight as using batteries but with the turbine, the fuel is burned off at 6.7 pounds per gallon. Battery weight stays the same either topped off or drained. The battery bird comes back with degraded performance, the hybrid comes home performing better than when departed.
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Last edited by DKTek; Mar 10, 2012 at 08:22 PM. Reason: additional $.02
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Old Mar 10, 2012, 09:35 AM
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Sullivan RC make a range of alternators for RC engines
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Old May 16, 2012, 04:06 PM
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Variation on the theme; Enya 90 conversion with twin plugs, running on gas, with integral generator, produced by Niklas Nyroth, ( now with Schiebel) for the "Buster" special forces area surveillance etc by Mitex, (Mission Technologies Inc.)
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Old Aug 22, 2012, 06:37 AM
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Hello,

I`m a Norwegian electro engineer and inventor.

I have a interest for UAV`s and quads. The micro generator questions raised here have puzzled me for many years, with different designs.

For now, the best results for my work:

Weight: 2320gram
Power: 1150watt continuous.

Electrical power can be delivered in any way you want, DC, AC (one or three phase). My design use a switching mode psu, lightweight, yet powerful.

Now, I have power to weight ratio of apporx 0.5watt/gram. It is possible to do better, when kW numbers go up or if I use a gasturbine as powersource. I use a O.S. glowmotor at the moment.
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Old Aug 22, 2012, 10:44 AM
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Quote:
Originally Posted by Hondaen View Post
Hello,

I`m a Norwegian electro engineer and inventor.

I have a interest for UAV`s and quads. The micro generator questions raised here have puzzled me for many years, with different designs.

For now, the best results for my work:

Weight: 2320gram
Power: 1150watt continuous.

Electrical power can be delivered in any way you want, DC, AC (one or three phase). My design use a switching mode psu, lightweight, yet powerful.

Now, I have power to weight ratio of apporx 0.5watt/gram. It is possible to do better, when kW numbers go up or if I use a gasturbine as powersource. I use a O.S. glowmotor at the moment.
Very interesting. Do you use regulator or switching psu only? I would like to know if you have schematic circuit diagram.
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Old Aug 23, 2012, 04:32 AM
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Hello

My design deliver adjustable 320 volt DC to 570 volt DC in a regulated steady-state.

Many reasons for this, but one of the best things about this design is the possibility to use the voltage direct into a common 220V AC 50Hz switch-mode psu, commonly available all over the world.

Reason: A ordinary switch mode psu first rectify the AC voltage into DC voltage. The DC voltage is square root of 2 higher the AC voltage value.

Thus, you can use 320V DC to direct-feed a normal computer psu (for example).

Or, you can feed a smal ABB frequency drive and get out whatever frequenzy or number of phases you want.

I hope this answer your question.

In designs (aero) that favor light weight, in my opinion, it is needed to go up with the voltage in order gain more fly-time. Higher voltage also means, in common, that Ah capacity of battery systems go up.

Losses rise with square root of the current, so we would like to minimize current

My spell: We will see more of high voltage setups in the future.
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Last edited by Hondaen; Aug 23, 2012 at 04:53 AM. Reason: Grammar
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Old Aug 25, 2012, 12:33 PM
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Old Dec 11, 2013, 11:09 AM
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Late reply

Not mentioned; applications. Frinstance, UAVs have to fly to area, loiter for data gathering, return to base; ie duration is important, turbines are too thirsty in small sizes!
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