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Old May 17, 2007, 08:55 PM
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Rural Westchester, NY
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Second the motion.

I would second that motion and say no, but I would add that my second plane was an E-Flite P47. As far as warbirds go it is extremely docile and an excellent second step.

On another note, I completed the motor conversion today by putting in an E-Flite 450 and an E-FLite 20 amp esc. Now it pulls 19.6 Amps and 200 watts and weighs exactly 20 ozs. On the bench the static amps are just over the max rated for the motor, but I'm counting on the fact that the prop will unload once airborne, and I suspect that all the limits are designed with a smidgen of forgiveness anyways. I guess we'll see, heh? Even though the replacement was only 4g heavier than the original (107g including esc and bolts) I had to add 0.4 ozs of lead to the tail to rebalance the plane probably because of all the epoxy I used to secure the wooden motor mount. No maiden yet. I'm hoping Monday. The switch was 2 hours of work. I had to use a wooden motor mount that I stole from a HL foamie kit, attach it to the plastic mount, epoxy it to the side walls for strength. Then I had to ream the prop, and trim off the inner lips on the prop base and prop inorder for the prop adapter to reach completely through the prop and hub. I'm excited to try the new motor, but if I were to do it again I would find a bell type motor that fits the existing motor mount. That would greatly simplify the process. Also, for what it is worth, I tried a HiTec crystal in the RX and it was not compatible.

Joe
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Old May 17, 2007, 09:07 PM
The sky is my playground.
Dora Nine's Avatar
United States, NH
Joined May 2005
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I'm sorry, I must have missed it but what prop are you using with the 450 and getting 200 watts? Thanks!
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Old May 17, 2007, 09:11 PM
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Prop.

No- I should have said - I'm using the stock 4 bladed 10x6 that came with the original kit. I edited the original post to explain that I am aware of the fact that 19.6 amps is just over the listed 18 amps, but I figure it will unload once airborne, and I don't anticipate hitting full throttle except for very brief bursts. I, also, noted that when I used a less than fully charged battery I got only 15 amps. I used a couple different calculators to try and estimate the amp draw prior to ordering the motor and 15 amps is what I expected. I was honestly surprised by the 19.6 amp reading. I guess careful throttle management will be the word of the day.

Joe
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Old May 17, 2007, 09:29 PM
The sky is my playground.
Dora Nine's Avatar
United States, NH
Joined May 2005
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Gotcha, I'm just looking to increase the wattage of my Alfa Corsair and other planes with a 450 under the hood. Thanks!
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Old May 17, 2007, 10:06 PM
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Brandon, Fl
Joined Mar 2005
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Joe

I'm going to closely follow your progress with the 450 and the stock prop. Truthfully, if the stock prop and spinner just didn't look so good, I would have dumped the old motor after 1 flight.

I plugged the numbers into MotoCalc and it predicts a pretty potent setup but warns the battery may not be up to the task. I have no idea what the c-rating on the battery is, I'd be surprised if it is above 10. So with the stock battery, you may expect to draw 13amps before the wheels come off the cart. Also - the stck ESC is rated for 18 amps. Bottom line - tread carefully, you are pushing just about all the powertrain components past their ratings. But then again, I never tell a Bumble Bee that is shouldn't fly.

Jim
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Old May 18, 2007, 04:26 PM
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Potent setup!

I think you're right, Jim, this setup will definitely be "Potent"

I'm not that familiar with MotoCalc so forgive me if this is a seemingly stupid question, but does MotoCalc have a prediction for prop RPM, amps, and watts using a better 3s battery? And is it optimized for an E-Flite 450 in particular or do you simply plug in the motors characteristics?

It's just those concerns that made me swap out the stock ESC for the E-Flite 20 Amp and made me plan on using my TP 1320 mAh LiPos which are rated for 17 amps continuous and 26 amp bursts and which are identical in shape and size to the stock battery. Plus I am hoping that since we both measured something close to 120 watts static, but your data logger showed inflight watts well under 100 that the same will hold true for this combo. I ordered an Eagle Tree Data Logger and I really expect to see something less than 15 amps and less than 160 watts maximum in flight. I guess we'll see . . .


On a slightly different note, can anyone out there think of a bell type outrunner that weighs 75g or so, can handle 200 watts, has a kv around 800 to 900, and has a 10mm motor mount shaft?

Just wondering . . .


Joe
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Old May 18, 2007, 05:02 PM
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Brandon, Fl
Joined Mar 2005
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Joe

MotoCalc is a must have for ball parking a new setup. You can download it here <http://www.motocalc.com/> and try it for 30 days. There are lots of user contributed elements and it is highly customizable.

Regarding your second note, the TP2409-18 fits just about all your requirements - though I think the shaft is probably 8mm.

TowerPro Brushless Outrunner TP2409-18

Model: 2409-18
Weight: 70g
Voltage: 10v (2~3 Cell lipo pack)
Idle Current: .9
Kv: 1000
Shaft: 3mm Diameter
Max efficient current: 15.5A
Max Load: 20A
Max Power Output:180W
Suggested Propeller: 8*.3.8 or 8*6 GWS Hyper Drive

Jim
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Old May 19, 2007, 11:47 PM
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Brandon, Fl
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Another successful sortie with the slowest P-51 on the planet.

The ROG is a joy to behold, if the gear clacked up at the end of the runway, it would be a scene right from 1944. I tell you, if it didn't look so good in the air, I would have ripped the motor out after the first flight. But no - it looks great. Just so ssssllloooowwwww. Hopefully Joe will tell us that the transplant was successful and all external beauty was retained. This a a gorgeous looking P-51, it even flies OK, better than OK - just slow.

Jim
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Old May 21, 2007, 02:04 PM
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Rural Westchester, NY
Joined Oct 2005
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E-Flite 450 maiden today.

So I flew one battery worth on the E-Flite 450 today. The performance was much improved. Wide loops, easy recovery from stalls with no loss in altitude, and plenty of pull in the vertical, though not "unlimited". Mostly I ran around at 1/2 to 3/4 throttle with only the occassional "goose" to max. I put 6 mins 40 secs on the flight and drew 874 mAhs out based on the re-charge with my BC-6 charger. (No data logger yet.) If I did my math correctly that works out to and average wattage of about 85 versus the 70 watts or so for the data chart Jim posted earlier. Looks to me like this is a winner of a setup, except its too bad the installation was such a pain in the . . .

Gonna try for video and more data tomorrow

Joe
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Old May 21, 2007, 03:55 PM
What can I crash today?
GeekGod's Avatar
Louisville, KY
Joined Oct 2006
659 Posts
Received my P-51 from HL today that I bought from their current sale. Everything arrived in excellent shape. No dings or marks on the outter box, everything is in awesome shape with exception of one piece on the nose (the black area) that had come off. I simply took a sharpie to it and you cannot really tell. Look forward to finishing this build over the week.

Quick question, however. Anyone think that a E-Flite 400 is overkill for this plane?
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Old May 21, 2007, 06:29 PM
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Brandon, Fl
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I don't think the 400 is too much for a Mustang - excess power is never a bad thing in a P-51. But the 400 is probably in the middle of the power band. E-flite says it is for models 10 - 20 oz and the P-51 is right around 20 oz. Bigger question is whether the beautiful stock prop and spinner is too much for the motor.

Hey Joe! Were you able to salvage the stock prop and spinner on the 450?

Jim
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Old May 21, 2007, 09:03 PM
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Stock prop.

Hey Jim,

Yeah, I really need to catch up and put some video and pictures up of my "suped up" P-51 because aside from the motor change everything else is stock including the prop and the spinner, so it ran today with the stock prop on the E-Flite 450. The guys at the flying field were all amazed at how good she looked especially sitting static with the 4 bladed prop. I really love my P-51! Can't wait to get the data logger because I'd love to know what is truely goin' on in flight.

Joe
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Old May 21, 2007, 09:26 PM
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Brandon, Fl
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Joe

Most definitely. I really want the P-51 to fly the way it should. Is it fast or really fast?!

Please take some pictures of how you installed the motor and adapted the prop to the shaft.

Thanks for being the guinea pig.

Jim
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Old May 22, 2007, 12:13 AM
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Louisville, KY
Joined Oct 2006
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Thanks for the replies! It turns out that it is a 450 so I will go ahead and use it with a 9x6". Was able to seat each servo tonight and get everything aligned. I really enjoyed putting everything together.
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Old May 22, 2007, 08:46 PM
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Joined May 2007
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Hi everyone! I ordered the p-51 mustang from hobby-lobby and i just got it today and its installed and ready to go but i am not. I have some questions on flying an airplane. ok so, when you throttle up, the back of the plane is going to lift and its not going to be easy to take off like that. What do i do on the controller to keep the back down so that the propeller does not toch the ground? Also, the airplane also came with a simulater that can connect to the controller of airplane right to the computer. I tried it out but the controls on the computer are reverse. Throttle up is left stick down. Is that how its gonna be when i fly it? Also, since i dont know how to get to one of those rc air fields, i am going to fly it in a field that has four baseball fields. Is that enough and since its all grass, would it be possible to launch it from the diamond (between the second base and third base)?

Thanks for all of the info.
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