Hi everyone. Took my first flight with the SP140 (Chill Mode) and found that when flying down wind i was struggling to stay level at full power. Wind was about 8-10 MPH and have the 2 blade prop. Wondering if sport mode will give me a boost in power to make it more comfortable when down wind? Also wondering if there is a huge difference between 2 and 3 blade prop?
Btw, this is the same wing i fly using my Moster MY20 (25M Charger 1). I weigh 185lbs so all in about 265lbs
Battery was at 98% but i don’t know what the output was. TBH I’m out sure how to interpret the numbers at this point. I had thrust and the prop was installed correctly. I haven’t tried sport mode so that’s my next step. I was curious if 3-blade vs 2-blade makes a meaningful difference though.
Fly up wind?
Seriously, the wind direction over the ground makes zero difference to your aircraft’s performance. Zero!!! I’m assuming the ground is close to level. Upwind/downwind/across the wind, you’r climb rate in feet/min, or power required to fly level will not be affected. Your ground speed can change.
I don’t have the sp140 but from reading other posts here it has, adequate, power even in chill mode. If you need full or nearly full power fo stay level on a fresh battery then either your wing loading is really high (small wing, heavy pilot or both) or there is a problem.
Did you install the propeller facing forward? Believe it or not they do work if installed flipped over just not very well. So that would require full power to stay level for sure.
the fact that you need significantly more motor power when flying ppg in downwind conditions is completely normal and an aerodynamic principle resulting from the angle of attack and speed. at ppg you can speak of around 20% more power when flying downwind compared to zero wind to maintain altitude. if you fly against the wind, you need around 10 to 20% less power to maintain altitude. a paraglider reacts differently to the angle of attack than an airplane with rigid surfaces. therefore it can happen that pilots of airplanes think ppg pilots with their knowledge about airplanes well meant to convince. yes, a 3-blade propeller usually has a significantly better efficiency value at ppg than a 2-blade propeller with the same diameter and input power +speed from the motor. 2 blade is usually around 50% efficient. 3 blade reach up to 55%
I do a lot of aerial mapping work in a Pipistrel virus aircraft and find that I always require more power flying downwind vs upwind, have to keep the nose pointed up to maintain altitude in downwind leg, usually require about 10-20% power increase to maintain altitude on downwind leg and higher nose up attitude. This doesn’t seem to be the case at high altitude but low altitude when there are decent 10-20knot winds will require this extra power and pitch up attitude.
I would like to see a good physics explanation from someone who can tell me why flying against the wind is different from flying with the wind.
As fast as you are airborne you have nothing to do with the ground any more but with the air around you, and if it is stationary or moving relative to the ground it doesn’t matter. you have your speed relative to the air around you.
What can happen is that you are in a rise Thermal or fall wind, I once experienced that I did not get off the ground and found out that at that moment this was a descending wind, in some places the air rises because it is warmer than the environment and comes loose from the earth, in other places that air must be replenished and the air therefore goes down.
I had 1 x with a longer cross-country flight that I could hardly stay at my 300 m 1000 ft only full throttle, but a lot further it went up everywhere and I closed the throttle.
That is why I do like to fly the first ore last 2 hours off daylight
Than the air is most quiet.
Normal I have a climb rate off around 1,5 m 6 ft with my Nucleon XX 26 and am 1.9 m 6,3 ft and 110 kg 240 lbs.
Just you all talk about 1 hour flight I have now 4 flight till almost empty battery and do not come further as 30 min !!!
With my Nirvana instinct 200 I use 3,5 ltr fuel and the other friends in my group all of which are a lot lighter consume 4 ltr
so my consumption cannot vary that much, the pressure per m2 is not much higher and I use a foot pocket which makes me well streamlined
just a tip: you can easily check for yourself how flying against and with the wind behaves, as well as with crosswinds. simply fly an equilateral fai triangle at the same height, for example 300 meters above ground with a wind speed of around 15-20 km/h. the direction doesn’t matter. you will find that each individual route requires a different power / speed from the motor in order to maintain the exact altitude. I myself automatically log all data from the eppg and all gps data from the flight instrument. but it’s enough if you simply film the values with a gopro, for example. Basically, it is enough to know that this is the case. Of course you can look for a scientific explanation, but this will not change the fact as it is in practice. Of course there is a lot of specialist information about aerodynamics, but a lot has long been proven that it was just theory from individual people and not reality.
If you write that you can only fly 30 minutes with the sp 140 i see it as completely normal with the total weight and wings you describe. with a hybrid wing in size 31, 40 minutes are certainly possible at your weight, but only if you are doing little altitude or only gentle climbs. this can all be checked mathematically. However, not like many think with pure calculation of values. you also have to include the cell load, which changes the possible capacity depending on the motor power. the warmer the battery gets, the less power is available for the flight. this is pure physics.
Just a couple mornings ago I flew my Atom 80 powered Amaruk. As is typical I flew upwind to start out. I was flying level per my Garmin D2. RPM around 7600 which I’ve previously noted will give me level flight give or take a few RPM depending on air temp, humidity, alt. etc. Everything was nice and the Garmin D2 was showing 30kph ground speed.
I then turned back, downwind. When I got flying straight again and confirm with my D2 I’m still flying level at about the same altitude. Then check RPM, 7600. Ground speed increased to 34kph. Power remained the same.
Well… only a 2kph wind! Not enough to notice any RPM change? Thing is, I’ve done the same mission in 10, and even 15kph wind and I watch the same instruments tell me the same rpm is required for level flight whether I’m traveling 42kph over the ground downwind or 22 kph over the ground upwind. In fact I use ground speed checks to keep tabs on the wind speed and direction while flying level. How else would i know?
That morning on my way back to LZ I felt a bit of turbulence as the sun got warmer and higher. I checked the Garmin again and was mildly surprised to see I was now traveling 45kph over the ground. Still straight and level. No change in RPM.
simply explained: a wing with little trim speed, e.g. A or low B class according to EN with a thick profile and little wing loading, e.g. 26 m2 and 110 kg total mass is little disturbed by the wind at less than 10 km/h in relation to the power consumption. a pure reflex motor glider with a higher trim speed due to more weight per m2, for example. 26 m2 and 140 kg will be disturbed at 10 km/h wind more than the previous example. Everything is only really noticeable when there is more wind, around 15 km/h. on my trike with very high surface loading of the wing and trimmer half open, it has a much greater effect. I fly with zero wind TAS 60 km/h with 20 km/h wind it is then 80 km/h with the wind and 40 km/h against the wind ground speed. as an example, i can already see a difference in performance of around 2-2.5 kilowatts that i have to adjust. to keep the same height. if you want to fly fai triangles, the influence of the wind is decisive for the time factor as well as for the fuel and power consumption.
Of course if you’re flying a route over the ground the wind affects your time, speed, and bearings required to fly those lines over the ground. The wind will not effect power required for level flight unless that wind has a vertical component as well. How could it?
try it: start with a motor at 10 km/h against the wind and then fly 100 meters exactly against the wind with food drag. note the speed or log it. then do the same with zero wind. I bet you need more RPM in the food drag in zero wind. then do the whole thing and do a food drag circle at 10 km/h wind. I’m 100% sure that if you take off against the wind then you don’t increase the speed then when you get into the first quarter you can never make a circle because if you fly with a downwind you won’t have enough power that the wing will hold you in the air. a food drag circle with constant gas in wind is impossible. This proves very well that a paraglider reacts differently to angle of attack and thrust than an airplane. but I’m happy if you make a video and show us that the wind doesn’t make a difference.
Your experiment can’t work close to the ground because of wind gradient. The wing and motor are both experiencing different freestream velocities.
In the air, assuming strictly horizontal component winds and assuming steady non-gradient air, the aerodynamics don’t care if you have a headwind or tailwind. The wing trim speed is constant. If you are flying level, then you are flying the same airspeed regardless of wind direction. If the aerodynamics are the same, the level power requirement is also the same.
OK. I have already said everything that a ppg with a motor changes aerodynamically due to the thrust and the resulting pendulum and therefore slows down the trim speed and generates more lift. I know, however, that only very few, mostly wing designers, understand this. often it is only walkers who see better than ppg experts because the wing is far behind the pilot against the wind than with the wind. but that’s another story that many ppg pilots don’t understand either. the ppg pilots who also use the ppg motor as a thermal assistant only for climbing know very well how a ppg actually works in relation to thrust, trim speed, headwind and angle of attack. as this can often be very dangerous. That’s why most standard ppg fly correctly when there is little wind and no thermals. Thanks to the reflex technology, it can also be flown in harsh conditions without the wing becoming unstable. This is also at the expense of efficiency and often requires an incredible amount of power because the angle of attack is deliberately extremely blocked by the reflex profile. so I won’t bother you anymore. maybe some of you will show in the future how to fly large fai triangles with little power requirement even with a lot of downwind … i can’t do it
Aerospace is my educational background. The wing flies according to the freestream velocity of the air not the wind. In steady-state conditions, the freestream velocity that the wing experiences is the same regardless of the wind direction. If the freestream velocity is the same, then the wing L/D is the same, the “pendulum” is the same, the power required to balance L/D is the same. Quite simply, the wing doesn’t know the direction of the wind because it doesn’t care.
I don’t understand why you bring up FAI triangles or foot drag loops. Of course, you will cover ground differently based on wind direction and wind gradient. That is not related to the power required to maintain level flight in steady-state conditions.
an example: a pilot A says that he studied aerospace and has been flying gliders for 30 years. only from the mountain in calm gentle conditions about 30 minutes gliding flights. but 30 years of flying experience and an unbelievable amount of expertise in aerodynamics!!
Pilot B is a very young craftsman and has been flying paragliders every free minute for 2 years in all weather conditions. taught himself every imaginable maneuver and acro skill over a lake with other acro pilots and has already successfully flown at world championships. is disciplined and attaches great importance to safety in his actions.
A and B are now sitting in a lift gondola and are being asked by other non-pilots what they do and how long they have been flying. many will think that pilot A is the expert in paragliding. he’s been flying for 30 years and has a master diplome in aviation. I say that pilot B is the true expert in paragliding because he has a multiple of specialist knowledge about paragliding than pilot A who does not even have 10% of the flying skills of B.
B has automatically learned the latest specialist knowledge and technical understanding of the paraglider. how could the A have been learned many years ago when today’s high-end wings didn’t even exist? easy to say in aerodynamics everything has been the same for decades?
you can always think for decades school book opinions are correct, or think freely and use modern measurement methods to form your own picture off paragliding.
but often it is not important who is right or wrong since it cannot be changed anyway. only how you deal with it is important to have fun and to be able to fly safely.
Think of a helicopter hovering. Does the power requirement to stay steady change if the heli is pointing into the wind or with it? What about from one side or the other? Any heli pilots around to confirm my suspicion? The aircraft performance could be slightly affected by some extra drag produced by flying backwards vs forwards but that would be all. Wind from the left or right would certainly require the same power requirement to hold altitude.
Air is air, lift is lift. Physics and aerodynamics are the same for paramotors as they are for 747s or helis or other light aircraft.
My very modern gps watch and the tach on my motor show that 7600rpm gives level flight regardless of my ground speed.
Just made a short flight this evening. Into a 20+kph wind holding altitude at 7300 or so. Altitude was 1400’ amsl so performance is quite good. Turned back and ground speed jumped from 10 to over 50. Altitude unchanged. RPM unchanged.
to the helicopter, yes, if it is a right-handed system and the wind comes from the right when hovering stationary, it will sink slightly since the rotor is always slightly inclined / approx. 2-5 degrees) because of the force generated by the tail rotor to compensate. if the wind comes from the left, the heli will rise slightly because a kind of air cushion is created when flying forward. a heli therefore requires significantly less power in horizontal flight than when hovering. but you know that if you fly an rc heli, if you fly an rc heli very low in the opposite way to mowing a lawn, the same side always hits the ground first.
I am very happy that you can keep the altitude exactly with the same rpm on the propeller. many of my friends who take professional aerial photographs have wished for a long time that this is possible with a paraglider and a motor.
it is particularly interesting when: you fly a large circle with a diameter of approx. 300 meters in a wind of approx. 15 km/h with a trike and travel gas and a timmer set for the curve radius. the whole thing some times you arrive at the same height as you started. however, in the track you can see a kind of waves in the height profile. 2 times going up and 2 times going down per circle. the height varies between 20 meters plus and 20 meters minus. I suspect that this only occurs with me because my physics are different