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Re: [Paparazzi-devel] Re: it is soooo cold outside

From: Reto Büttner
Subject: Re: [Paparazzi-devel] Re: it is soooo cold outside
Date: Sun, 5 Dec 2010 09:35:59 +0100

It is amazing what flight performance can be achieved by flying a
simple cheap foam airframe at its optimal point. Paparazzi is a
powerful tool to optimize the flight parameters.

Another inspiration:

Mark Griffin won the UAV altitude contest 2009 by maximizing gained
altitude per consumed energy. He found the ideal climb angle, flight
speed and propeller. He used a simple EasyStar to reach the impressive
cumulative height of 19'819ft (6'041m):

Cheers, Reto

2010/12/3 Christophe De Wagter <address@hidden>:
> Nice Work!
> Just as inspiration: we followed a less sophisticated approach to maximize
> the flight time (ca 35min) of our brushless + 4.2Ah + 600gr payload
> twinstar. Not the fancy polar from airspeed but: "an onboard realtime
> current sensor" -> search for cruise throttle that yields minimal Amps.
> BTW: If you use the polar to define the optimal speed: does this include the
> effects of varying motor efficiency with speed? (if your props are too big,
> maybe a lower speed might yield a better total efficiency & vice versa)
> For the climbing we optimize vclimb[m/s]/current[mA] to reach a maximal
> altitude[m] out of 1 battery[mAh]. This is more difficult to tune as there
> are 2 parameters.
> -Christophe
> On Fri, Dec 3, 2010 at 9:26 PM, <address@hidden> wrote:
>> more details? no problem
>> I started with a regular setup of a twinstar. probably like everyone
>> else... termopiles gps nothing special
>> what is special is that during the time I changed to brushless motors
>> 2 x viper2700 with 2x 25 ESC
>> and a 5Ah lipo
>> in this configuration I made 30 min
>> after a while i started playing with different pressure sensors, we
>> already discussed that
>> and then I wrote my one vertical control and implemented a bunch of new
>> autopilot modes that enables my twinstar to fly constant airspeed with or
>> without throttle
>> due to these new modes I was able to gain the polar and to find speeds for
>> best glide and minimum sinkrate
>> so with a slightly pimped flightplan I made 46 min with 5Ah
>> so what really disappointed me  no matter what I tried I couldn t make the
>> 60 minutes
>> no I just put a lot of capacity in it ... I know 5Ah is a already a lot
>> but now there are 12Ah in this little airframe and they just fit perfectly
>> I already figured out the polar and you can clearly see that the speed for
>> best glide is much higher as well as the speed for minimum sinkrate
>> there is only the time problem for me and the fact that I m a one man show
>> so I have to carry everything on my back to the airfield and be operator and
>> safety pilot at the same time
>> during the summer there was no need to ask for people to help me because
>> everyone wanted to see it but right now at these low temperatures it is
>> getting really hard to find someone freezing especially when its only  for
>> an endurance test and the plane is only doing wide circles.
>> so thats it
>>  a piece of foam and a lot of battery -- imagine how much more should be
>> possible even with this setup
>> cheers
>> Tobi
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