Is there a particular reason why you initiate the thrust vector into the harness? I noticed literally all foor launchable propulsions do so - whoever, what is the particular reason ehelp can't be attached directly to the keel tube? Many thanks & best wishes!
The center of mass is the only place where the thrust of 34 kg can be directed to obtain positive pitch stability. The glider total drag is about 10-15 kg and the rest of the thrust is used for lifting the mass. Placing the thrust vector in the glider frame, like on the keel, could cause a forward pitch and unstability. Putting a significant amount of thrust in the frame is to put it simply - very dangerous. It could kill You.
Hello Reidar, I talked with a Model Plane Expert. He said it would be the better Choice, to take a Gear to to take the Speed down and work with a small fast Motor. I think of Planetary Gear and the Folding Prop Combination. As you can see, I fly an Atos. What do you think? By the Way, nice Work! And so much Thanks that you have make an really good Introduction!
svesom I have flown a geared version which I called the Mossie quite a lot. It geared the Rotormax down from 7700 rpm to 2200 and drove a big 128 cm diameter prop. However it is big and a bit cumbersome. And the big torque affected the handling on the glider a bit. So even though very powerful and efficient, I prefare the small lightweight direct driven as seen on this video. The Mossie often propelled my fixed wing Axxess+ and it is almost like a small sailplane. I launced from a special dolly when flying from airfield. Check video on my channel.
The real C rating of Zippy's are pretty low. Example: when E-Help runs at normal full take off and climb power it is 140 amperes. From 4 battery packs that is 35 A each pack and 35/5,8 is 6 C's. If putting a heavy prop on it and climbrate 2 m/s it is fuelburn 180 A. Zippy will then overheat and in some cases puffing up and destroying cells, especially on hot summer days. 180 A from 4 packs are 45 A each pack and C load at 35/5,8 is then 7,8. Advertised C rating is 25C but that can only be for very short burst I think, like few seconds. When loaded in several minutes mabe it can do 15C. However, for flat out long climb the full battery capacity our experience says no more than 6-7C. We have destroyed some Zippys mostly due to aggressive flying trying to outclimb sink areas, especially with the old 150 KV and small prop version which had bad prop efficiency. This days we have the more efficient 105 KV with 34x14 or 34x12 props that are lower amp draw for more thrust. My personal E-Help has 6000 mAh batteries at 35C that is about same story but a bit better than Zippys. The one one the videos black colour packs. Some cheap chinese internet batteries. If U go to Lithium Carbone batteries it is way better C but the price increase does not justify it. Then it is cheaper to just replace a cheap cell if overloaded.They doesent blow up like people are afraid of. But You can't say that out load on internet bcs all the Trolls of course knows this much better ;-)
I know the energy density numbers of the Zippy Compacts are sexy on paper, but they don't hold up in the real world. Tattu or even just regular blue turnigy packs or flight max packs will outperform and cycle longer. Don't get fooled by the green multistar packs either ;p
MrElectricglider The switches are some low cost retail switches normally used for isolating batteries in small boats. Rated for 100 amp at 12 or 24 volts. You get them in boat shops or like here in Norway at Biltema or Clas Ohlson.
MrElectricglider It is 100 amper low voltage switches from regular hardware shop. Normally used for 12 volt boat battery main switch. Can only be operated in no load condition.
Dear Reidar, thanks a lot again this video, genious! (I'm waiting for Hobby King ship). I think if you continue your work on this way, it will not only hang gliding, but smartgliding soon. :-) I have already read a lot your posts, but I dont remember (sorry) which prop do you prefer, which one is better if I couldn't rewind my Rotomax, the Menz 34x14 or lighter? Best wishes, Istvan
Hello Istvan, I can only talk scientificly for the rewound 105 KV motor. Which has undergone a lot of ground testing and experiments. Plus 3 years of flight testings. For that one at 14s (52 volts) the Menz 34x14 gives marginal flatland take off capability at about 32-35 kg thrust provided that the battery can supply 140 amps without cooling/ overtemp issues. With the smaller Student version we can only go 34x12 prop because the smaller battery there only should be loaded 70 amperes. Student only gives 20 kg thrust and zero sinker capability with a 80 kg pilot and single surface glider. In Your case with a standard 150 KV motor You should go 12s batteries to slow down rpms and supersonic tip speed issues. Various other people have tested the 150 KV and it may indicate that props in the 30x10 and 30x12 range are not too bad with 12s. Get some 30 kg thrust at horrific high amperes it seems like, have seen 160 amperes and even more which is hard for the batteries. The amperes increase almost exponential when hitting the last 20% top rpm's so it is pretty sensitive and need a well tuned ground test program to become safe and sound. Most people that has taken this config out flying without too much grond testing at workshop have burned the motor stator windings. The standard Rotormax 150 will burn at something above 170-180 amperes. My friend Boris is running a program on the 12s and 150 KV this days and it looks not too bad. It's gonna fly a WW Falcon 4 at 170 sq feet with a 80 kg pilot and lightweight harness + E-Help rig. Probably some 10-12 kg lighter TOW than I usually fly and that makes a lot of difference.
Thank you so much your reply. If I understand you well , - following Boris project - I can to reduce the voltage from 51,8V to 44,4 V? The Ampers will not increase too high when the BLDC motor start to work? For example I can buy 4 x Alien 6S 10 000 mAh 35C Lipo Battery, (2s2p will 44,4 Volt ), and won’t cause problem the lower voltage than 51,8 V? I have an old MAGIC-4, it is a little bit havy, so I have at least 40 kg thrust I think. (I’m about 80 kg.) I’ve found formerly a static thrust calculator on the net, ( www.godolloairport.hu/calc/strc/ ). According to calculator I need 34”x12” prop, and if my motor can 9,72 kW, and 4950 RPM, I get 39,82 kg static thrust. (the prop speed will under the sound speed 223,71 m/s) The Rotomax 150 CC can 9,8 kW, and 7770 RPM, but I’m not sure that, the motor characteristic is capable, at least 4950 RPM with 34”x12” prop, and meanwhile the amps won’t increase over 160A. (?) Honestly.. I’m measuring to sell the new Rotomax 150 CC and buy a new one, other type with lower KV parameter. Thank you if you can confirm my data. Best regards, Istvan
István Molnár Your numbers are fairly correct except for the robustness of the Rotormax motor. It will become very hot and very close to burning the stator windings. The Magic 4 is not an ideal PHG glider as it is heavy and slack. Much better off with an lightweight floater at 170-190 sq feet.
Brilliant Reidar . Are you considering a mouth accelerator(wired I believe due to the remote size of the wireless) like in nrg ? For take-offs I beleive It's a very safe option. Cheers and Happy New Year with many and safe flights ( ' burning ' electrons or not :)
Hello, yes we looked at it and have a small potensiometer mouth version prepared for that. You will need a thin electric wire between the bite thing and the wireless transmitter though. First I will try flatland start with the wireless hammer handle that is easy to hold against the upright. If it is still too ackward then considering moving on to the mouth accellerator. Everything is better than todays solution when it comes to flatland start. Whith the wired accellerator velcroed to the shoulder strap You have to hit full thrust with one hand off the upright. And it is easy to go wrong there being pushed forward. And when that happens it's difficult to cut power. So I have some splintered wooden props from failed flatland launches in zero wind that is mostly caused by beeing pushed out of balance. With some wind it is OK because the glider floats more by itself. But in zero wind it is outright dangerous with shoulder accellerator.
Reidar Berntsen. Thanks for reply. I'm eager to see the evolution. Let me share my views. In our static line towing for the tandem glider and ss student the safest was bike brake release in the speedbar. I use for my comp glider finsterwalder 2 step kock2. Never tested towing (US pull release), all of these have the major inconvenient of in the critical moment (e.g. lockout) we have to take our hand of the glider. As someone think before (and being tottaly agnostic of the method used to put us up there) the safest by far is any mechanism that allow us to have both hands in command ( either base tube or uprights) in the two critical phases TO and landing.If no dolly is used mouth control is the way to go. Cheers.Andre
Is there a particular reason why you initiate the thrust vector into the harness? I noticed literally all foor launchable propulsions do so - whoever, what is the particular reason ehelp can't be attached directly to the keel tube? Many thanks & best wishes!
The center of mass is the only place where the thrust of 34 kg can be directed to obtain positive pitch stability. The glider total drag is about 10-15 kg and the rest of the thrust is used for lifting the mass. Placing the thrust vector in the glider frame, like on the keel, could cause a forward pitch and unstability. Putting a significant amount of thrust in the frame is to put it simply - very dangerous. It could kill You.
do you have a circuit diagram for the precharger, please?
G'day Reidar, what is the brand name of the car controller handle you are using?
I dont remember, it was picked up at a RC hobby shop
Hello Reidar, I talked with a Model Plane Expert.
He said it would be the better Choice, to take a Gear to to take the Speed down and work with a small fast Motor.
I think of Planetary Gear and the Folding Prop Combination.
As you can see, I fly an Atos.
What do you think?
By the Way, nice Work!
And so much Thanks that you have make an really good Introduction!
svesom I have flown a geared version which I called the Mossie quite a lot. It geared the Rotormax down from 7700 rpm to 2200 and drove a big 128 cm diameter prop. However it is big and a bit cumbersome. And the big torque affected the handling on the glider a bit. So even though very powerful and efficient, I prefare the small lightweight direct driven as seen on this video. The Mossie often propelled my fixed wing Axxess+ and it is almost like a small sailplane. I launced from a special dolly when flying from airfield. Check video on my channel.
Nice setup. FYI, I have had terrible luck with the Zippy Compact cycle life and they are nowhere near their rated c-rate.
The real C rating of Zippy's are pretty low. Example: when E-Help runs at normal full take off and climb power it is 140 amperes. From 4 battery packs that is 35 A each pack and 35/5,8 is 6 C's. If putting a heavy prop on it and climbrate 2 m/s it is fuelburn 180 A. Zippy will then overheat and in some cases puffing up and destroying cells, especially on hot summer days. 180 A from 4 packs are 45 A each pack and C load at 35/5,8 is then 7,8. Advertised C rating is 25C but that can only be for very short burst I think, like few seconds. When loaded in several minutes mabe it can do 15C. However, for flat out long climb the full battery capacity our experience says no more than 6-7C. We have destroyed some Zippys mostly due to aggressive flying trying to outclimb sink areas, especially with the old 150 KV and small prop version which had bad prop efficiency. This days we have the more efficient 105 KV with 34x14 or 34x12 props that are lower amp draw for more thrust. My personal E-Help has 6000 mAh batteries at 35C that is about same story but a bit better than Zippys. The one one the videos black colour packs. Some cheap chinese internet batteries. If U go to Lithium Carbone batteries it is way better C but the price increase does not justify it. Then it is cheaper to just replace a cheap cell if overloaded.They doesent blow up like people are afraid of. But You can't say that out load on internet bcs all the Trolls of course knows this much better ;-)
I know the energy density numbers of the Zippy Compacts are sexy on paper, but they don't hold up in the real world. Tattu or even just regular blue turnigy packs or flight max packs will outperform and cycle longer. Don't get fooled by the green multistar packs either ;p
I have used the blue turnigy packs for RC planes and those where OK
Awesome vids! Will you be selling these in the near future?
No, too much work, risk and time more than the 6 units flying locally.
what budget do you have for all the material ???
Michel Trevisan About 1500 UER in material for the Student. Depends mostly on battery selection.
hello reidar, which power switches do you use? type? Ampere? where do you get these from? thanks for info lg werner
MrElectricglider The switches are some low cost retail switches normally used for isolating batteries in small boats. Rated for 100 amp at 12 or 24 volts. You get them in boat shops or like here in Norway at Biltema or Clas Ohlson.
MrElectricglider It is 100 amper low voltage switches from regular hardware shop. Normally used for 12 volt boat battery main switch. Can only be operated in no load condition.
Dear Reidar, thanks a lot again this video, genious! (I'm waiting for Hobby King ship). I think if you continue your work on this way, it will not only hang gliding, but smartgliding soon. :-)
I have already read a lot your posts, but I dont remember (sorry) which prop do you prefer, which one is better if I couldn't rewind my Rotomax, the Menz 34x14 or lighter?
Best wishes, Istvan
Hello Istvan, I can only talk scientificly for the rewound 105 KV motor. Which has undergone a lot of ground testing and experiments. Plus 3 years of flight testings. For that one at 14s (52 volts) the Menz 34x14 gives marginal flatland take off capability at about 32-35 kg thrust provided that the battery can supply 140 amps without cooling/ overtemp issues. With the smaller Student version we can only go 34x12 prop because the smaller battery there only should be loaded 70 amperes. Student only gives 20 kg thrust and zero sinker capability with a 80 kg pilot and single surface glider. In Your case with a standard 150 KV motor You should go 12s batteries to slow down rpms and supersonic tip speed issues. Various other people have tested the 150 KV and it may indicate that props in the 30x10 and 30x12 range are not too bad with 12s. Get some 30 kg thrust at horrific high amperes it seems like, have seen 160 amperes and even more which is hard for the batteries. The amperes increase almost exponential when hitting the last 20% top rpm's so it is pretty sensitive and need a well tuned ground test program to become safe and sound. Most people that has taken this config out flying without too much grond testing at workshop have burned the motor stator windings. The standard Rotormax 150 will burn at something above 170-180 amperes. My friend Boris is running a program on the 12s and 150 KV this days and it looks not too bad. It's gonna fly a WW Falcon 4 at 170 sq feet with a 80 kg pilot and lightweight harness + E-Help rig. Probably some 10-12 kg lighter TOW than I usually fly and that makes a lot of difference.
Thank you so much your reply. If I understand you well , - following Boris project - I can to reduce the voltage from 51,8V to 44,4 V? The Ampers will not increase too high when the BLDC motor start to work? For example I can buy 4 x Alien 6S 10 000 mAh 35C Lipo Battery, (2s2p will 44,4 Volt ), and won’t cause problem the lower voltage than 51,8 V?
I have an old MAGIC-4, it is a little bit havy, so I have at least 40 kg thrust I think. (I’m about 80 kg.) I’ve found formerly a static thrust calculator on the net, ( www.godolloairport.hu/calc/strc/ ). According to calculator I need 34”x12” prop, and if my motor can 9,72 kW, and 4950 RPM, I get 39,82 kg static thrust. (the prop speed will under the sound speed 223,71 m/s) The Rotomax 150 CC can 9,8 kW, and 7770 RPM, but I’m not sure that, the motor characteristic is capable, at least 4950 RPM with 34”x12” prop, and meanwhile the amps won’t increase over 160A. (?)
Honestly.. I’m measuring to sell the new Rotomax 150 CC and buy a new one, other type with lower KV parameter. Thank you if you can confirm my data. Best regards, Istvan
István Molnár Your numbers are fairly correct except for the robustness of the Rotormax motor. It will become very hot and very close to burning the stator windings. The Magic 4 is not an ideal PHG glider as it is heavy and slack. Much better off with an lightweight floater at 170-190 sq feet.
Brilliant Reidar . Are you considering a mouth accelerator(wired I believe due to the remote size of the wireless) like in nrg ? For take-offs I beleive It's a very safe option. Cheers and Happy New Year with many and safe flights ( ' burning ' electrons or not :)
Hello, yes we looked at it and have a small potensiometer mouth version prepared for that. You will need a thin electric wire between the bite thing and the wireless transmitter though. First I will try flatland start with the wireless hammer handle that is easy to hold against the upright. If it is still too ackward then considering moving on to the mouth accellerator. Everything is better than todays solution when it comes to flatland start. Whith the wired accellerator velcroed to the shoulder strap You have to hit full thrust with one hand off the upright. And it is easy to go wrong there being pushed forward. And when that happens it's difficult to cut power. So I have some splintered wooden props from failed flatland launches in zero wind that is mostly caused by beeing pushed out of balance. With some wind it is OK because the glider floats more by itself. But in zero wind it is outright dangerous with shoulder accellerator.
Reidar Berntsen. Thanks for reply. I'm eager to see the evolution. Let me share my views. In our static line towing for the tandem glider and ss student the safest was bike brake release in the speedbar. I use for my comp glider finsterwalder 2 step kock2. Never tested towing (US pull release), all of these have the major inconvenient of in the critical moment (e.g. lockout) we have to take our hand of the glider. As someone think before (and being tottaly agnostic of the method used to put us up there) the safest by far is any mechanism that allow us to have both hands in command ( either base tube or uprights) in the two critical phases TO and landing.If no dolly is used mouth control is the way to go. Cheers.Andre
The release mechanism in my channel when I'm playing with student Falcon. ruclips.net/video/lBsN_eKvorc/видео.html