Наткнулся на интересную тему рцгрупсе http://www.rcgroups.com/forums/showthread.php?t=2108955
Там чел воткнул два ака 3S по 4,7Ач (кажется, сейчас страница с didrones недоступна) -получил 6S. Поставил движок мультистар 400 об\в и проп 10х10 (да, да с шагом 10) и пролетел на данном сетапе 114 км, съев только 68% ака. Неплохой результат, что думаете?
Пробовал в калькуляторе что то подобное посчитать - получается что бы срыв потока на лопастях прекратился нужно кинуть самолет со скоростью 30 км\ч))
Вот основные тезисы которым чел следовал.
The following three rules of thumb for propulsion have proven to work well for long endurance and long distance and might solve some of the mystery of the prop discussion:
#1: Prop pitch ratio around 1 (as already stated, recommended by Dr. Martin Hepperle)
#2: Pitch speed a bit under double the cruise speed or triple the stall speed. This corresponds to the fact that best cruise speed is typically around 1.5 of the stall speed. This is knowledge of the guys of ecalc.ch and corresponds to my personal experience.
#3: Propulsion power around 100W/kg.
Example: You have a plane of 2kg flying optimal cruise at 75km/h. You then want 200W propulsion power at pitch speed around 130km/h. That is met with a 10x10 prop turning at 7200rpm. Make sure you choose a motor that meets these requirements and is efficient at low workload. You will be flying cruise around 25% power.
Based on the three rules of thumb the prop and motor dimensioning follows these steps:
1. Weigh your plane.
2. Find best cruise speed (best glide, best L/D ratio) for your airframe. Typically it is around 1.5 the stall speed.
3. In a calculation program (e.g. ecalc.ch) play around with motors (try different kV resp. rpm/V) and propellers (try different diameters, stick to pitch ratio 1) until you get:
- Maximum power around 100W/kg flight weight
- Pitch speed a bit less than double the cruise speed
- Motor has a reasonable efficiency both at cruise (25%) and at full power.
- Ignore the propeller stall at static thrust.
This is an easy way to find a good starting point for your long endurance and long distance drive chain.