P-38 Lightning Brotherhood
08-03-2014, 09:33 PM
#551
Ragtop,
"It seems there’s a bit more rocket science to large electrics than I anticipated.I’m hoping someone here can give a little guidance on how to “size airframes to motors to esc’s to prop’s, etc.”
I can can only speak of my own experience, but the eflite power systems have been great choices for me. They are easy to match to the airframe as they are sized to the appropriate glow sized motor. For example, the eflite power 60 matches up to a 60 sized glow. The power 160 equals a 160 sized glow engine. On each motors box, it will tell you the correct sized ESC from eflite to use. It tells you exactly what battery's to use, and they will also give you the appropriate prop range for each motor. It will go on to give 3 or 4 "real world" setups for you to compair. It will give you the model used in, ESC used, battery setup and prop selection for each model in examples.(usually one warbird, one trainer type, sport type, and 3d)
As far as quality goes, I've had no complaints. Everything's worked as advertised. It takes a lot of the guess work out of it for you.
Casey
"It seems there’s a bit more rocket science to large electrics than I anticipated.I’m hoping someone here can give a little guidance on how to “size airframes to motors to esc’s to prop’s, etc.”
I can can only speak of my own experience, but the eflite power systems have been great choices for me. They are easy to match to the airframe as they are sized to the appropriate glow sized motor. For example, the eflite power 60 matches up to a 60 sized glow. The power 160 equals a 160 sized glow engine. On each motors box, it will tell you the correct sized ESC from eflite to use. It tells you exactly what battery's to use, and they will also give you the appropriate prop range for each motor. It will go on to give 3 or 4 "real world" setups for you to compair. It will give you the model used in, ESC used, battery setup and prop selection for each model in examples.(usually one warbird, one trainer type, sport type, and 3d)
As far as quality goes, I've had no complaints. Everything's worked as advertised. It takes a lot of the guess work out of it for you.
Casey
08-04-2014, 07:39 AM
#552
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Casey: eFlite’s MO of labeling their eMotor’s to nitro sizes is the limit of my ePower knowledge. There are soooo many options – Scorpion, Turnigy, etc. – that do not label their motors that way that have me baffled.
Ragtop: Whoa! Thank you VERY MUCH for all of the info! I have homework to do!
I’d prefer to fly it at a more leisurely pace and have flight times of 5 minutes or so. I did some research on our planes. Your NP has much more wing area (7.53sq ft. vs 5.9 sq. ft.) than the VQ, but at 23lbs and 18lbs (estimated) respectively, our wing loading is roughly equal at 48oz/sq. ft.
VQ says this model should come in at 16lbs. I’m assuming that’s with the “recommended” .46 size nitros, no retracts and no fuel. Mine has Robart retracts and batteries.
While I do not want to under-power it, I don’t think I’ll need the kind of horsepower your NP has. I’m thinking .60 sized eMotors should fly it reasonably well. Hopefully the info you’ve supplied will help me to understand how my Turnigy’s and your Scorpions equate to nitro sizes… or should I be shooting for “watts to lbs.”?
Another thing... I want to run three blade props of "sorta scale" sizes.
As always, we’re still learning… so any and all comments are appreciated!!!
Ragtop: Whoa! Thank you VERY MUCH for all of the info! I have homework to do!
I’d prefer to fly it at a more leisurely pace and have flight times of 5 minutes or so. I did some research on our planes. Your NP has much more wing area (7.53sq ft. vs 5.9 sq. ft.) than the VQ, but at 23lbs and 18lbs (estimated) respectively, our wing loading is roughly equal at 48oz/sq. ft.
VQ says this model should come in at 16lbs. I’m assuming that’s with the “recommended” .46 size nitros, no retracts and no fuel. Mine has Robart retracts and batteries.
While I do not want to under-power it, I don’t think I’ll need the kind of horsepower your NP has. I’m thinking .60 sized eMotors should fly it reasonably well. Hopefully the info you’ve supplied will help me to understand how my Turnigy’s and your Scorpions equate to nitro sizes… or should I be shooting for “watts to lbs.”?
Another thing... I want to run three blade props of "sorta scale" sizes.
As always, we’re still learning… so any and all comments are appreciated!!!
Last edited by sudstad; 08-04-2014 at 07:43 AM.
08-04-2014, 09:45 AM
#553
Sub,
I agree most manufactures do not use this method, but as eflight does, and their product is fairly priced and seems to work like a Swiss watch...why not try them? I use them for all my electrics other than a few giant scales that were too large for the power 160....although, now they have the power 360...so I'll go back to them in e futer for larger setups as well
I agree most manufactures do not use this method, but as eflight does, and their product is fairly priced and seems to work like a Swiss watch...why not try them? I use them for all my electrics other than a few giant scales that were too large for the power 160....although, now they have the power 360...so I'll go back to them in e futer for larger setups as well
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Tippytwowire (07-28-2020)
08-04-2014, 10:26 AM
#554
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I have no problem with non-eFlite stuff... especially those recommended by members of this brotherhood as Ragtop has done for Scorpion! I already have a pair of Turnigy's that I'd love to use! I just don't know if they're powerful enough for this application. I'd prefer to fly at moderate/scalelike speeds... AND not have to run the motors at full throttle all of the time.
My biggest issue is how to identify the correct size motor for my airframe... when they're not labeled by nitro size. Regarding the specs below, what is the appropriate method of choosing motors?
VQ factory specs:
Specifications:
Wing span: 82.7" (2,10m)
Fuselage length: 57.5" (1,46m)
Weight: 14.4 - 16.6lbs (6500 - 7500g) - Actual AUW will be 17.5lbs to 18lbs.
Req. Engines:
My biggest issue is how to identify the correct size motor for my airframe... when they're not labeled by nitro size. Regarding the specs below, what is the appropriate method of choosing motors?
VQ factory specs:
Specifications:
Wing span: 82.7" (2,10m)Fuselage length: 57.5" (1,46m)Weight: 14.4 - 16.6lbs (6500 - 7500g) - Actual AUW will be 17.5lbs to 18lbs.Req. Engines:Twin .40 - .46 (2-cycle)
Twin .52 - .70 (4-cycle)
Thanks!
Sig
Twin .52 - .70 (4-cycle)
Thanks!
Sig
Last edited by sudstad; 08-04-2014 at 10:30 AM.
08-04-2014, 01:27 PM
#555
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Ragtop,
I just watched your long video for the hundredth time. Whew! That sound is awesome!!!
I also just looked at the Scorpions you're running. they're physically smaller and lighter than the Turnigy's that I have, but are tremendously more powerful! Was that flight on 6s 5000 batts?
I just watched your long video for the hundredth time. Whew! That sound is awesome!!!
I also just looked at the Scorpions you're running. they're physically smaller and lighter than the Turnigy's that I have, but are tremendously more powerful! Was that flight on 6s 5000 batts?
08-04-2014, 01:44 PM
#556
That was on 6S packs. I ended up adding batteries just to bring up the total weight, so I am carrying a lot of batteries. There is a 4000 and 5300 6S pack in each boom, could probably fly around for 10 minutes. I think I am going to change motors and run a pair of 160's in it on 10S....carrying the extra weight around already
If you're looking for leisurely flying, the Master Airscrew props are probably your best bet, just need to decide if you like the looks of 16" or 14". I still say go with the Scorpions, maybe run them on 5S instead of 6S. Less weight
If you're looking for leisurely flying, the Master Airscrew props are probably your best bet, just need to decide if you like the looks of 16" or 14". I still say go with the Scorpions, maybe run them on 5S instead of 6S. Less weight
08-04-2014, 02:58 PM
#557
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Great!
I'm beginning to think the Scorpion S-4025-12's and some 6s batteries might be my best option. This is based on their ability to pull a 23lb airframe as vigorously as they do! And that they're lighter than the other options that I've looked into.
Judging by your Flight 5 Slow Pass video, I think my flights will be mostly slow flight including some higher/full throttle maneuvers. We already have 6s batteries of various sizes. For this kind of flying, how many 6s mAh do you think I'd use in a five minute flight?
I'm beginning to think the Scorpion S-4025-12's and some 6s batteries might be my best option. This is based on their ability to pull a 23lb airframe as vigorously as they do! And that they're lighter than the other options that I've looked into.
Judging by your Flight 5 Slow Pass video, I think my flights will be mostly slow flight including some higher/full throttle maneuvers. We already have 6s batteries of various sizes. For this kind of flying, how many 6s mAh do you think I'd use in a five minute flight?
Last edited by sudstad; 08-04-2014 at 05:10 PM.
08-04-2014, 05:53 PM
#558
Substad
If you went with the Scorpions, I would think you would end up with something like this using MA16x10x3 props:
5S setup, around 1200 watts each, straight and level at full throttle. You would be pulling around 65-70 amps, flying around 65 MPH. With a 4000MHA battery, looking at about 3 1/4 minute flight time, 4500mah looking at 3 1/2, 5000mah battery, looking at around 4 minutes. That's if you fly the whole flight at full throttle. Add a minute or so as I would imagine you would pull the throttle back during flight. I have not run these motors on 5S, so this is all guestimated
6S setup, the motors a trying to get to their no load RPM, which is roughly 10K (440 times voltage), so the amps will be much higher.
This is the data from the flight I did with the MA 16x10x3 props. A smaller lighter plane will be slightly lower on the load side, slightly higher on the speed side. Rough data only, prop made a bunch of noise on 6S, thinking they would be happier on 5s
Takeoff: 2081 watts 87.2 amps 8061RPM
downwind leg 1634 watts 70 amps 8870rpm
Flyby 1029 watts 43.3 amps 9548 rpm
Climbout 1789 watts 79.1 amps 8529 rpm
vertical 2137 watts 92.4 amps 7984 rpm
S&L average 1577 watts 67 amps 8600 rpm
A three minute flight, most of which was at full throttle used 2750mah from the packs, I landed with 3.833 volts per cell.
Casey is right, the E flite products are also very good products. To help make some sence of this, the OS 55AX ABL makes 1.68hp at 16000 RPM. Since it makes that power at such a high RPM, no way it will spin a 16" prop. The Saito 72 makes "1.2hp" but can swing much larger props at a lower RPM, although I couldn't find specfices.
The 6S setup above makes roughly 2.3 hp during takeoff, which is its peak. Average cruise power is around 1.8 Hp at 8600 RPM, if you fly at full throttle.
To relate numbers to engine HP ratings, figure the rated watts (max contiguous amperage rating of motor * voltage you plan to run), multiply that time .85 (efficiency estimate) the divide by 746. Our S&L cruise number above 1577 watts. (1577 watts* .85) /746 = 1.7968 HP at the prop.
Overpowered? A little, but that doesn't mean you have to use it. If you end up with 14" props, the motors will just be cranking along happy as can be for a very long time, as they aren't being taxed at all. Remember, an electric will only try to spin up to its rated KV speed, once it gets there, the amperage/wattage goes way down
Hope this helps
If you went with the Scorpions, I would think you would end up with something like this using MA16x10x3 props:
5S setup, around 1200 watts each, straight and level at full throttle. You would be pulling around 65-70 amps, flying around 65 MPH. With a 4000MHA battery, looking at about 3 1/4 minute flight time, 4500mah looking at 3 1/2, 5000mah battery, looking at around 4 minutes. That's if you fly the whole flight at full throttle. Add a minute or so as I would imagine you would pull the throttle back during flight. I have not run these motors on 5S, so this is all guestimated
6S setup, the motors a trying to get to their no load RPM, which is roughly 10K (440 times voltage), so the amps will be much higher.
This is the data from the flight I did with the MA 16x10x3 props. A smaller lighter plane will be slightly lower on the load side, slightly higher on the speed side. Rough data only, prop made a bunch of noise on 6S, thinking they would be happier on 5s
Takeoff: 2081 watts 87.2 amps 8061RPM
downwind leg 1634 watts 70 amps 8870rpm
Flyby 1029 watts 43.3 amps 9548 rpm
Climbout 1789 watts 79.1 amps 8529 rpm
vertical 2137 watts 92.4 amps 7984 rpm
S&L average 1577 watts 67 amps 8600 rpm
A three minute flight, most of which was at full throttle used 2750mah from the packs, I landed with 3.833 volts per cell.
Casey is right, the E flite products are also very good products. To help make some sence of this, the OS 55AX ABL makes 1.68hp at 16000 RPM. Since it makes that power at such a high RPM, no way it will spin a 16" prop. The Saito 72 makes "1.2hp" but can swing much larger props at a lower RPM, although I couldn't find specfices.
The 6S setup above makes roughly 2.3 hp during takeoff, which is its peak. Average cruise power is around 1.8 Hp at 8600 RPM, if you fly at full throttle.
To relate numbers to engine HP ratings, figure the rated watts (max contiguous amperage rating of motor * voltage you plan to run), multiply that time .85 (efficiency estimate) the divide by 746. Our S&L cruise number above 1577 watts. (1577 watts* .85) /746 = 1.7968 HP at the prop.
Overpowered? A little, but that doesn't mean you have to use it. If you end up with 14" props, the motors will just be cranking along happy as can be for a very long time, as they aren't being taxed at all. Remember, an electric will only try to spin up to its rated KV speed, once it gets there, the amperage/wattage goes way down
Hope this helps
Last edited by 70 ragtop; 08-04-2014 at 06:07 PM.
08-04-2014, 07:10 PM
#559
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That helps... probably more so once I re-read and hopefully understand it more thoroughly!
I'd rather be over-powered and throttle-back once in the air.
We already own a good mix of 6s batteries... from 3800 to 5000's (all 30c and up), so I'd prefer to go that route. I'll have to check ground clearance to figure-out max prop size.
These motors appear to be discontinued, so I guess I'd better act fast. Do you have a recommended dealer?
I'd rather be over-powered and throttle-back once in the air.
We already own a good mix of 6s batteries... from 3800 to 5000's (all 30c and up), so I'd prefer to go that route. I'll have to check ground clearance to figure-out max prop size.
These motors appear to be discontinued, so I guess I'd better act fast. Do you have a recommended dealer?
Last edited by sudstad; 08-04-2014 at 08:06 PM.
08-04-2014, 07:30 PM
#560
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08-04-2014, 10:11 PM
#561
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Sudstad.
When I have to chose a motor for a new project I usually go to a manufacturer and get their opinion as a place to start. Lately I have been using Motrolfly motors. Before everyone else tells you, they are not cheap. However last year I was having a conversation with the techs at Castle Creations and they said the Motrolfly motors are the most efficient brand they have tested. I have had them in everything from 32" foamies to a Beast 60e and they are robust, and run cool. A very good thing here in Las Vegas! When I have called them, Ken has always been most helpful in motor decisions and there is a free motorcalc program on his web site to help with your decision making. I Just don't put in something to save a few bucks. I have enough problems worrying about my flying, I don't want to have to worry about my electronics.
When I have to chose a motor for a new project I usually go to a manufacturer and get their opinion as a place to start. Lately I have been using Motrolfly motors. Before everyone else tells you, they are not cheap. However last year I was having a conversation with the techs at Castle Creations and they said the Motrolfly motors are the most efficient brand they have tested. I have had them in everything from 32" foamies to a Beast 60e and they are robust, and run cool. A very good thing here in Las Vegas! When I have called them, Ken has always been most helpful in motor decisions and there is a free motorcalc program on his web site to help with your decision making. I Just don't put in something to save a few bucks. I have enough problems worrying about my flying, I don't want to have to worry about my electronics.
08-04-2014, 11:15 PM
#562
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I would like to join the brotherhood. I have a YA P-38 that I've had for some time. This is a 20+ year old kit. When they were still being made in the USA. I stopped working on it in '06. Need idea's for doing fowler flaps. I'm also a big P-51 fan.
08-05-2014, 11:41 AM
#564
You have to order from them directly. They introduced a newer version, and were selling pretty much everything at 50% off. I had them in 4 days....from China, which amazed me http://www.scorpionsystem.com/catalo...0_1/S-4025-12/
BTW, not pushing 16 props, that's all I've tried on those motors. They may not look right on the VQ, might be better off going smaller......
I was going to try the 15.2" adjustable pitch props on these motors, but never pulled the trigger. My cowls need work to run the right sized spinners, and I was worried about max RPM on 6S, so I didn't do it. Might be perfect on the VQ, on 5S. A little smaller, lighter plane using 5 S might be the way to go. Believe me, I know all about making batteries fit everything, I don't have any 5S batteries either. This one might work with those props on 6S. http://www.scorpionsystem.com/catalo.../SII-4025-330/
http://www.ramoser.de/home_e/variopr...rioprop_e.html
BTW, not pushing 16 props, that's all I've tried on those motors. They may not look right on the VQ, might be better off going smaller......
I was going to try the 15.2" adjustable pitch props on these motors, but never pulled the trigger. My cowls need work to run the right sized spinners, and I was worried about max RPM on 6S, so I didn't do it. Might be perfect on the VQ, on 5S. A little smaller, lighter plane using 5 S might be the way to go. Believe me, I know all about making batteries fit everything, I don't have any 5S batteries either. This one might work with those props on 6S. http://www.scorpionsystem.com/catalo.../SII-4025-330/
http://www.ramoser.de/home_e/variopr...rioprop_e.html
Last edited by 70 ragtop; 08-05-2014 at 01:38 PM.
08-05-2014, 12:02 PM
#566
Not aware of any Yellow models running Fowler flaps, but I feel sure someone has done it. There are a few posts on this thread around #154 from Scale Dail. Can also checkout the Ziroli build threads, G-Pete's build thread here on RCU comes to mind. Look thru a few pages starting around page 6 http://www.rcuniverse.com/forum/rc-w...g-build-6.html. Robart makes Fowler flap brackets
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Last edited by 70 ragtop; 08-05-2014 at 12:09 PM.
08-05-2014, 06:33 PM
#567
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I had a lengthy conversation with the Horizon Hobby folks this afternoon. After describing my project, they recommended a pair of Power 90's and Castle Edge 100's.
Any thoughts... comments?
Any thoughts... comments?
08-05-2014, 07:40 PM
#568
6S setup 1110 watts (rated continuous), 7215RPM no load speed. roughly 6132 loaded. 10 pitch prop tops out <60MPH S&L loaded. 18 pound plane would be roughly 123 watts per pound (rated)
Scorpian 4025-12 rated 85 amps continuous, no burst listed, but it will pull 110 amps, 12.24 oz, 440 KV $80
5S setup 1572 watts (rated continuous), 8140 RPM no load speed, roughly 6919 loaded. 10 pitch tops out 65MPH S&L loaded. 18 pound plane would be roughly 174 watts per pound (rated)
6S setup 1887 watts (rated continuous), 9768 RPM no load speed. roughly 8302 loaded. 10 pitch tops out 78 MPH S&L loaded. 18 pound plane would be roughly 209 watts per pound (rated)
What the numbers don't show, is if the motor is able to spin your chosen prop close to its no load speed, it prop will unload, and amperage will go way down. It will no longer be pulling hard, it will be maintaining current speed, bank hard, or climb and props will load right back up.
Take a look at the numbers I posted above. You can see during a descending flyby, the RPM was the highest, and the amperage was the lowest. The motors were getting close to their no load speed and unloaded. When I used APC 15.75x13x3, the motors kept pulling hard, with high amp numbers, even during a dive. That's why that setup was so fast, (video post 495) those props did not unload
The Scorpions are great little motors, you don't have to prop it to go fast. You can prop it for the way you want to fly, and the motors will barely be working up a sweat
Last edited by 70 ragtop; 08-05-2014 at 07:49 PM.
08-06-2014, 06:29 PM
#569
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No doubt my friend. They pull your Lightning around like it's a jet!
After a fair amount of thought and debate, I'm going with the eFlite 90's... for a few reasons. Mainly because I won't need the same power as yours does. I'm thinking my airframe is roughly 10% smaller that your NP, plus it's about 20% lighter.
And I'd like to say Thank You for all of your input. I'm still trying to understand all of the great information that you shared. It will definitely help as we gain experience in large epowered rc. And... I'm really looking forward to your next videos!
After a fair amount of thought and debate, I'm going with the eFlite 90's... for a few reasons. Mainly because I won't need the same power as yours does. I'm thinking my airframe is roughly 10% smaller that your NP, plus it's about 20% lighter.
And I'd like to say Thank You for all of your input. I'm still trying to understand all of the great information that you shared. It will definitely help as we gain experience in large epowered rc. And... I'm really looking forward to your next videos!
08-06-2014, 08:00 PM
#571
Anytime! E-flite makes a great product, with great support, and they're available everywhere to boot. I think you will be very happy
Please post some progress pictures!
19.9" Vario-Prop blades arrived today. Planning to round the tips a little, just to eliminate the point. The 18" blades looked pretty good, these look just a little bit better. Big question is will the motors be able to spin them for some more of that "jet like" performance
Hope to finish up battery hatches, remaining glass and bodywork and get it into primer before the weather changes. Thought about flying it as is, but as I have a bit of actual "bodywork" to do before any primmer, and it makes such a mess, decided to get all the heavy stuff done first on the bare airframe, then fit the gear doors, vertical, tail servos, rods, and prime it. Doesn't look like its going to fly this summer
Please post some progress pictures!
19.9" Vario-Prop blades arrived today. Planning to round the tips a little, just to eliminate the point. The 18" blades looked pretty good, these look just a little bit better. Big question is will the motors be able to spin them for some more of that "jet like" performance
Hope to finish up battery hatches, remaining glass and bodywork and get it into primer before the weather changes. Thought about flying it as is, but as I have a bit of actual "bodywork" to do before any primmer, and it makes such a mess, decided to get all the heavy stuff done first on the bare airframe, then fit the gear doors, vertical, tail servos, rods, and prime it. Doesn't look like its going to fly this summer
Last edited by 70 ragtop; 08-07-2014 at 10:01 AM.
08-08-2014, 01:24 PM
#574
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Nice!
I waiting for the outcome of Derek's Lighting build thread: http://www.rcgroups.com/forums/showthread.php?t=1450191
Hopefully he'll start making kits.
I waiting for the outcome of Derek's Lighting build thread: http://www.rcgroups.com/forums/showthread.php?t=1450191
Hopefully he'll start making kits.
08-08-2014, 04:29 PM
#575
Hey guys, General Hobby has the 90" Nitro planes P-38 listed as in stock. Pictures don't match, but description and price sound right. Grab them while you can
http://www.generalhobby.com/lightnin...ver-p-230.html
http://www.generalhobby.com/lightnin...ver-p-230.html