I posted this in the electrics forum and got a limited and single response that did not offer any solution. The gentalman sudjested I by a wattmeter as though I would know what those numbers ment anyway. I simply want to be able to safely fly this little speed deamon without killing batteries (my wallet) or any other components I cant fix on my work bench I am thinking by reading another thread here and playing with the online calcu;ator that I may need about a 35A ESC and a battery that can handle a larger amp draw (I think this is the "C" rating). Your help is always apreciated. below is what I posted in the electric forum.

I used a web based calculator [link=http://adamone.rchomepage.com/calc_motor.htm]here[/link], that was posted in another thread, to check my set up which I know flys but sure gets hot. I try to only hit full throttle in short bursts so I don't light the farmers feild on fire. Last time I flew the plane I did a high speed pass down the runway and pulled up only to watch my wings fold up on me. Well I got it repaired and will be taking it out again next week.

The plane is a Hett Tucano 27.25 in wing span about 1.25-1.5 Lbs
Battery: Thunder Power 1320 13/20C
ESC: Castle Creations Pheonix 25A
Motor: EFlight BL 420 DF (I know I'm running a prop with a DF motor)
Prop :APC 4.5x4.5

I am very limited on space for componets in this plane but I would be very interested in sudjestions to get this thing to quit getting so hot (you cant even hold the battery after a flight without a glove).

hi stang,

im far from a pro but it sounds like your pulling more amps than the battery pack can deliver with that small a prop and high KV motor.

im not famaliar with that plane but you might want to try a lower kv motor (outrunner) and a bit larger prop and higher c rated battery. if i read your post right the battery pack is only a 13c with bursts to 20 c ? and is it a 2S or 3S pack ?

can you post a link to the plane you have so we can get an idea of whats needed ? also is there room to swing a larger prop ?

hmmm think i found it, is this the plane ?= http://www.rcgroups.com/forums/showthread.php?t=472505


if that is it a motor like this = http://www3.towerhobbies.com/cgi-bin...?&I=LXLWT2&P=0 would make it fly pretty well i would thinkand you could still use your ESC and battery pack using there suggested props.


ie... 7.4 volt (2S pack) want to use the 10x4.5 and on 11.1 volt pack (3S) you want the 9x4.5 .

i hope i helped some.



bassman

Yes, you found the plane as posted in that link of yours. This plane is an experiment in speed for me so I'm really not interested in going backwards to the factory recomended motor and batteries. If anything, I want to go faster. I already folded the wings once on this plane and now have them glassed so I hope they are stronger than when they were new. You read correctly as far as my battery pack being 13C w/ 20C burst and they are 3 cell packs and a larger prop goes slower and a 9-10 inch prop would look comical on this little bird. What I am hoping is that someone can point me towards batteries and/or ESC's that may make my plane hit 150 mph.

stang,

well good luck with getting it set-up that way, im not much into speed when i fly so im not much help to you , but you will most definialty need a high KV motor and a better battery pack that can handle the amps you will be seeing some of the newer 30 and 40 c packs might work for you.

also if you know of anyone with a watt meter see if you can get them to help, as watt meters can save your battery electric components from getting fried if your pulling more amps than they can handle.

but i dont think that little plane will ever be able to get even close to those speeds as some of the guys that fly turbine jets at my field have topped out 155 mph and thats moving


sorry i couldnt be more help to you .



bass

This plane has already hit ~110-120mph but it is running on a dangerous edge for the electronics and the airframe at that time (that is when the wings folded) I think I have the airframe set up to take it, now I want to get the electronics up to snuff. Remember it takes a lot less to get a 1 lb to go fast than a large turbine plane.

With what you posted and the graph that accompanied it, you are definately pushing your battery. A 13/20 battery is fairly old technology (like a computer, it is about 1.5-2 years old), but they have come a long way and now a 1320 20/30 or 30/40 can be had for about $20. Easiest thing would be to upgrade your battery. On the chart it says that you would be pulling about 23.9 A, which at you size battery is 23.9/1.320 = 18C. For you to hit your speed, assuming you are already doing 110 mph, you would probably have to double your power to the prop or maybe more, which is going to require doubling your current to the motor (That assumes the same efficiency, which is not correct). Knowing this you will have to change the following: Battery, ESC, Motor,Prop.

If you just want to fly the same as you have been doing, you should at least change the battery to something that can continuously pull 24A. Being that you have a CC25, you may want to upsize this for some overhead. I don't know what your motor is rated for, but you may want to check those specs too to make sure you are safe.

Hope this helps. If you need help finding a combo to get you to 150 mph, PM me and we can talk.
Best Regards,
Curtis

36000 rpm with a 4.1 x 4.1 prop will get you in the ball park.

Yeah, if the prop doesn't come apart.

CGr

Well I just swapped the ESC and battery. I installed another Castle Creations ESC that I am not sure what the Amp rating is but its bigger Must be better right? The battery is an XPower DualSky 1700 mah 35C/2C The prop spun noticably faster but at full throttle the motor quit. I back down to the bottom and I can run it again but if I go to full it just quits. I guess I am pushing to much through the motor now...Attached are pictures of the plane I am talking about.

Well, I'm a far cry from 36,000 rpm right now so my goal may not be realistic with this plane without JATO pods. I may need to do a scratch design

Stang,
That is one pretty bird. I got your PM, but haven't had much time to reflect on it. If you want to pursue doing electrics, the best thing to do right now is to get a wattmeter. If you want to spend some money, skip that but get an eagletree VS with the brushless sensor and the temp sensor. It will really help you figure out what is happening in your power system. I got mine with a $20 of $50 at Tower for about $65, money well spent.

My first impression is that you are either hitting your Low Voltage Cutoff on the ESC, or you are maybe hitting a thermal shutdown on the ESC, but I suspect that would not allow you to restart like the LVC issue. The datalogger would better help you determine what is happening.

We can get you your speed fix, but it may take a little time. Take a look at the other thread here in the beginner's forum about motor/ESC/Battery selection and I reference a program called DriveCalc. It's freeware and it is powerful.
Best Regards,
Curtis