H9 P-51 Electrification
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I am in the process of getting my brand new Hangar9 P-51 set up as an electric powered plane. I am starting this thread and asking all those that have much more knowledge than me, for their input on the motor selection. I am using one of the AXI motors sold by Hobby Lobby. I know there are the people that say use a Hacker or a MaxCim, etc. and I am sure they are fine motors. I just dont have that kind of income to buy a 600 dollar motor and then have to buy another expensive gearbox to accompany it, not to mention the speed control. The AXI is withnin my means so that is what I will go with.
I have questions about which of the larger motors that would work for the setup I desire. First, I want to have flight times of over 10 minutes, preferably close to 15 minutes. I like scale flying and I also like most out there like to mix it up and do some moderate areobatics. Next, I will be using the latest NiMH battery out that has the largest capacity, which I have found locally to my area to be the 3300 Mamp. Again, it is a cost issue to go with the NiMH. LiPO's would be great, but out of reach for me for the time being.
I have been told that I needed a 4120/14 and I think that is just too small. The all up weight will be at least 9,5 lbs and the 4120 just doesnt fit that bill. Mr. Greg Covey's F4U Corsiar conversion is what I have been following and I have asked him these questions as well. He has the LiPo batteries that would give me what I want in flight time and performance, however, I just cant afford going that route right now, so I have to go for the heavier NiMH batteries.
Looking below, I have copied from the chart the specs on the two different motors.
Examples of output for the AXI 413016: Am I correct with the below estimated
flight times.
Cells Prop RPM Current Watts
20 14x10 7140 39A 685 <--(This setup equals around 10 min. flight time.
24 14x10 8030 49.1A 975 AUW would be +/- 9,5 lbs.)
Examples of output for AXI 413020:
Cells Prop RPM Current Watts
24 16x8 7150 27.5A 612 <--(This setup equals around 14 min. flight time.
30 16x8 8360 31.2A 980 AUW would be +/-10 lbs.)
Greg Covey replied to the above question of motor selection and flight times as "sounds reasonable" so I think I am on the correct path. If I am in err, please chime in and give me suggestions. All responces are greatly appreciated and I will keep you informed on which motor selection I go with and how it performs, with flight times.
Thanks,
Longarm
I have questions about which of the larger motors that would work for the setup I desire. First, I want to have flight times of over 10 minutes, preferably close to 15 minutes. I like scale flying and I also like most out there like to mix it up and do some moderate areobatics. Next, I will be using the latest NiMH battery out that has the largest capacity, which I have found locally to my area to be the 3300 Mamp. Again, it is a cost issue to go with the NiMH. LiPO's would be great, but out of reach for me for the time being.
I have been told that I needed a 4120/14 and I think that is just too small. The all up weight will be at least 9,5 lbs and the 4120 just doesnt fit that bill. Mr. Greg Covey's F4U Corsiar conversion is what I have been following and I have asked him these questions as well. He has the LiPo batteries that would give me what I want in flight time and performance, however, I just cant afford going that route right now, so I have to go for the heavier NiMH batteries.
Looking below, I have copied from the chart the specs on the two different motors.
Examples of output for the AXI 413016: Am I correct with the below estimated
flight times.
Cells Prop RPM Current Watts
20 14x10 7140 39A 685 <--(This setup equals around 10 min. flight time.
24 14x10 8030 49.1A 975 AUW would be +/- 9,5 lbs.)
Examples of output for AXI 413020:
Cells Prop RPM Current Watts
24 16x8 7150 27.5A 612 <--(This setup equals around 14 min. flight time.
30 16x8 8360 31.2A 980 AUW would be +/-10 lbs.)
Greg Covey replied to the above question of motor selection and flight times as "sounds reasonable" so I think I am on the correct path. If I am in err, please chime in and give me suggestions. All responces are greatly appreciated and I will keep you informed on which motor selection I go with and how it performs, with flight times.
Thanks,
Longarm
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If I may chime in here, you're concentrating entirely too much on flight time, and not enough on power output. You're definitely on the right track in going with the largest AXi motors, but with the 9.5lb AUW you're expecting, you need enough power to haul it around. Flight times can be extended by throttling back, but if you've only got enough power to cruise at full throttle, you're not going to be able to do the aerobatics.
For a scale warbird, you need to be shooting for 100 Watts per pound because of the heavier wing loading. The 900+ Watt configurations will be more suitable for your P-51, even though you'll have to give up some flight time. 15 minutes AND heavy-metal warbird performance on NiMH, even 3300mAh, is a little much to ask.
For a scale warbird, you need to be shooting for 100 Watts per pound because of the heavier wing loading. The 900+ Watt configurations will be more suitable for your P-51, even though you'll have to give up some flight time. 15 minutes AND heavy-metal warbird performance on NiMH, even 3300mAh, is a little much to ask.
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I am in the midst of converting my previously glow powered H9 Mustang. I have installed an AXI 4130/20 with 24 GP3300 cells. I have run it and with a 15x13 I am showing 49 amps. I also tried a 17x10 and it pulls 59 amps; a little too much. I am sure this will be more than enough power.
I am hoping to finish it this weekend.
Jeff
I am hoping to finish it this weekend.
Jeff
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Does anybody know of a web site out there that has good deals on the Hacker, MaxCim, or the AXI motors. My cash is about to say goodbye to my wallet and I want to search out the best deal.
Come on guys, chime in here and give me some suggestions.
Longarm
Come on guys, chime in here and give me some suggestions.
Longarm
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To tell you the truth, there really hasn't been much variance in price from shop to shop. They're all pretty much trimmed down to the bare minimum as far as profit is concerned. For one to sell cheaper would mean selling at a loss...
My AXi came from Hobby Lobby.
My AXi came from Hobby Lobby.
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I got my batteries, AXI 4130-16 motor, Hacker Master 77 Opto ESC, motor mount, and UBEC today.
I am going with the NiMH GP3300 batteries for now. I bought two 12 packs that I will connect in series. When I save up the money, I will get LiPO's. Hopefully, by that time, their price will have gone down more.
Hopefully it will be together for the weekend.
I have a digital camera, but the only time I tried to post a picture in a thread, it didn't work, so I haven't tried since.
More to follow.
Longarm
I am going with the NiMH GP3300 batteries for now. I bought two 12 packs that I will connect in series. When I save up the money, I will get LiPO's. Hopefully, by that time, their price will have gone down more.
Hopefully it will be together for the weekend.
I have a digital camera, but the only time I tried to post a picture in a thread, it didn't work, so I haven't tried since.
More to follow.
Longarm
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Well, it is ready. Standard size servos that came with my Futaba radio, standard size retract servo, standard reciever, UBEC, Hacker Master 77 Opto Speed control, AXI 4130-16 motor, 24 cell GP3300 battery pack, pilot, spinner, and 14X10 APCE prop.
A fat 10lbs & 11 ounces. GOOD NIGHT!!!!!!!!!!!! That is a FAT CAT......
The nerves are starting to act up now.
Longarm
A fat 10lbs & 11 ounces. GOOD NIGHT!!!!!!!!!!!! That is a FAT CAT......
The nerves are starting to act up now.
Longarm
#9
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How is your ground clearance on the H9 P-51 with the 14x10 prop? If you can switch to a 15" prop, you can reduce your cell count.
The wingspan and wingarea of the P-51 look virtually the same as my H9 Corsair so it will probably fly ok even though you are about 1lb heavier than when my 9.5lb Corsair model used NiCd cells.
A trick I use when I think that I will be switching a model to Lithium cells is to use CP1700 NiCd cells instead of CP2400 or GP3300 cells. The weight difference is much closer when switching battery technology which results mostly a change in flight duration.
The wingspan and wingarea of the P-51 look virtually the same as my H9 Corsair so it will probably fly ok even though you are about 1lb heavier than when my 9.5lb Corsair model used NiCd cells.
A trick I use when I think that I will be switching a model to Lithium cells is to use CP1700 NiCd cells instead of CP2400 or GP3300 cells. The weight difference is much closer when switching battery technology which results mostly a change in flight duration.
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Holy Inverted Flight Batman, this thing screams!!!!!!![sm=spinnyeyes.gif]
I maidened the H-9 P-51 with the AXI 4130/16, 24 3300 Nimh cells, using the 14/10 APC-E prop. I have a big runway to use, but I had a crosswind to contend with. The windsock was telling me a constant 10mph wind with short gusts close to 15 mph. I decided to go for it a a diagonal track, as close to into the wind as I could get.
Take off was to say the least, scary as @%^$. I had the elevator level with the horizontal stab, but when it got up to speed, it went up with no elevator. (So I guess it needs some downthrust to correct that) Anyway, when it became airborn, it didn't have enough speed to stay level. tip stall, correct, tip stall, correct, tip stall and turn from wind, correct and it is now going straight to our vehicles [sm=drowning.gif]. I got a little speed going now, got some climb and flew straight over our vehicles at around 15 to 18 feet. The air speed increased and that joker began to climb at an aggressive angle, with no elevator.
I kicked up the retracts and trimmed her as best I could. It was hard to trim her out with my fingers shaking uncontrollably [sm=spinnyeyes.gif]. I flew for around a 5 minute maiden flight, did some rolls, loops and some inverted flight. Had a couple of jet guys watching and they were thoroughly impressed.
I brought her hot and did a mighty fine landing, if I do say so myself. Had one small bounce, less than 10 inches, but I settled her down nicely, and rolled straight out. No nose overs and it tracked straight down the runway. [8D] I taxied her back right up to us and that is when the elation hit. Man this thing is great. [sm=sunsmiley.gif]
Was up for 5.5 minutes or so, the battery pack was luke warm. I ran out the duration of the pack at half throttle and could have gotten another 2.5 or 3 minutes on the pack. Lipos will be coming, I just have to save my pennies.
I will get some pictures ready and try to successfully get them on here.
Thanks to all those that gave advice and suggestions. I really appreciate it.
Longarm
I maidened the H-9 P-51 with the AXI 4130/16, 24 3300 Nimh cells, using the 14/10 APC-E prop. I have a big runway to use, but I had a crosswind to contend with. The windsock was telling me a constant 10mph wind with short gusts close to 15 mph. I decided to go for it a a diagonal track, as close to into the wind as I could get.
Take off was to say the least, scary as @%^$. I had the elevator level with the horizontal stab, but when it got up to speed, it went up with no elevator. (So I guess it needs some downthrust to correct that) Anyway, when it became airborn, it didn't have enough speed to stay level. tip stall, correct, tip stall, correct, tip stall and turn from wind, correct and it is now going straight to our vehicles [sm=drowning.gif]. I got a little speed going now, got some climb and flew straight over our vehicles at around 15 to 18 feet. The air speed increased and that joker began to climb at an aggressive angle, with no elevator.

I kicked up the retracts and trimmed her as best I could. It was hard to trim her out with my fingers shaking uncontrollably [sm=spinnyeyes.gif]. I flew for around a 5 minute maiden flight, did some rolls, loops and some inverted flight. Had a couple of jet guys watching and they were thoroughly impressed.

I brought her hot and did a mighty fine landing, if I do say so myself. Had one small bounce, less than 10 inches, but I settled her down nicely, and rolled straight out. No nose overs and it tracked straight down the runway. [8D] I taxied her back right up to us and that is when the elation hit. Man this thing is great. [sm=sunsmiley.gif]
Was up for 5.5 minutes or so, the battery pack was luke warm. I ran out the duration of the pack at half throttle and could have gotten another 2.5 or 3 minutes on the pack. Lipos will be coming, I just have to save my pennies.
I will get some pictures ready and try to successfully get them on here.
Thanks to all those that gave advice and suggestions. I really appreciate it.
Longarm
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This is not the front of my mustang, but it is the motor mount that I used. It looks exactly like this, the ESC is mounted in the same way, with one exception. Mine is mounted on a wood spacer off of the bottom of the mount, putting it in the flow of air from the front of the opening of the cowl. The fire wall on the mustang was cut out in the shape of the cowl opening. The air comes in, crosses over the ESC, goes into the fuselage, over the batteries, and out of the bottom of the fuselage, just behind the oil cooler "hump". The air exit is two holse that are 1.5 inches in diameter and have soffit vents glued in the holes. I painted the white plastic soffit vents gray to match the color of the gray monocoat.
I hope this photo comes out. There will be more to come.
Longarm
I hope this photo comes out. There will be more to come.
Longarm
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Pictures of finished plane and me, final approach on a landing, and aftermath of crash after a servo bind causing the other servos to lock.
Longarm
Longarm