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- This topic has 18 replies, 2 voices, and was last updated 14 years, 10 months ago by Dohrman Crawford.
03/23/2008 at 9:56 pm #40827
I decided to start this new thread in hopes of collecting the kind of info that made E36 a much easier project. I am presently converting my old Bounty Hunter to electric and hope to make it a good to great flier. I have a bigger Top Banana, but I am going to wait and see how the Bounty Hunter flies first.
I have a pretty fair hobby shop here in Atlanta that does mainly electric models. Of course, they are all rc, but they have lots of knowledge on LiPos, connectors etc.
I took the BH bones with me to the hobby shop, and they recommended an ERunner motor with a 3 cell lipo on it. It is a Park 300 Outrunner, 1380 KV. It weighs 24 gms, RPM/volt is 1380. They recommended a 3 cell lipo with it and an esc from Castle Creations that is good to 10 amps.
The Bounty Hunter will weigh between 6.5 and 7 oz, ready to go. It has a 245 sq in wing. I have seen them fly with TDs, and even at that weight, they will go very fast.
Jim Jennings really likes the AXI motors. Jim, does this sound like it even compares at all to the AXI range of motors?
Also, do you guys use the GWS type props, or something by APC. Folders???
Sorry for all the questions, but I am wading out in the electric swamp!
03/24/2008 at 1:02 am #45555
Dohrm, Wade on in the water is fine! It sounds like you have a pretty good set up. Your wing loading is good. Is the battery rated at 20c? And what is it’s capacity? I do not have any experence with the Park brand motors but they are very popular with RC fliers. Our local hobby shop sells them as well. The AXI equivalent would be a 2204/54 it weighs 26g at 1400 KV.
I am excited that you are putting a “B” ship together. I am interested to know more about the battery to see how much power you will produce. Have you decided on a timer? Remember that you are only running the motor for a very limited time and can exceed the manufacturer’s recommendations a little when it comes to proping. Be sure to post some images. Does this mean that we will be flying “B” on the sod farm this year? 😀03/24/2008 at 1:41 am #45556
Dohrm, sorry I did not answer the prop question. You do need to use electric props. Gas props are too thick and will reduce the RPM. Straight or folded is your call. Do you have the clearence to fold the prop? If so I will share my method. If not the straight prop is very easy. Your motor most likely came with a prop saver, you should use it. You will be spinning something like a 7 X 5 or an 8 X 6 depending on which battery you are using. It may hang below the model, the prop saver will save you time and money. See straight props here:
I like to use CAM folders you can see them here:
Most gas conversions do not have enough clearence for a folder. If you decide to modify the model for a folder let me know, I machine my own hubs. You would need blades only.
03/24/2008 at 3:18 am #45557
Many thanks for the info. I just spent way too much time in the shop trying to get my computer there to hook into the internet and failing. Guess I need a Geek!!!
I will look up the battery info tomorrow. I appreciate the pictures, that helps a lot.
Yes, I am guessing there will be some electrons moving about at the sod farm this year. I know Graham Selick is pressing ahead with an electric rocket, and I think David Barfield is very interested also.
The Bounty Hunter may be a little short coupled for this sort of thing, but it certainly should prove interesting!
I covered the wing with Sig Orocover. First time I have ever tried the plastic stuff. I had no idea it was so easy!!! For now it looks good. We will see how she looks after the bullets start to fly!03/24/2008 at 3:20 am #45558
I forgot to mention I have ordered a Smoothie timer and will try the hot wire setup, or maybe a mini servo to run the DT. Not sure how that will turn out. I sure have no idea how to set it up, but it is doable.03/24/2008 at 1:08 pm #45559
The Smoothie is easy to use. I have an extra wire DT if you want it. Let me know if you need help with the wiring or anything else. I like Oracover on the wings and Coverite’s Microlight on the tail surfaces. It sounds like we may have some electrons moving about! I had better send Frank some money.03/24/2008 at 2:29 pm #45560
I failed in my attempts to get a photo of the battery. All my shots came out blurred. I will try again with a better camera, or a tripod. At any rate, it is a Thunder Power 3 cell LiPo of 480 Mah/11.1V. 15C cont/22C burst (7.2A/10.5A) I think the burst time is 15 seconds, but am not sure. I may have to find another battery, but will try this one and see how it goes.03/24/2008 at 2:39 pm #45561
Dohrm, You should come in at around 11 watts per oz. of model weight. Not Bad. This is my favorite lipo:
It would give you about 12.5 watts per oz. of model weight. Not a big difference. Your controller may not let you draw the additional amps anyway. I say better to have and not need……………………..03/26/2008 at 12:06 pm #45562
Thanks, however, I am electrically challenged. [little pc talk there for style points]. Are you using the 400 Mah battery or the 800 Mah battery? I am guessing you would use the 400 Mah battery. Or does that not have enough horsepower?
My Smoothie should be rolling in here any day now. I am looking forward to hooking this up and seeing how much junk I can blow off my bench and onto the floor. [That is assuming I succeed in hooking all this electronic junk up correctly.]03/28/2008 at 7:25 pm #45563
Yes I am refering to the 400 mah 3 cell. The Polyquest is a 20c constant discharge, 25c burst battery. Proped correctly you should draw around 9 amps. and make close to 100 watts of power. I get excited just talking about it! You will blow up more than balsa dust with that! let us know!03/28/2008 at 7:36 pm #45564
Hot Dog, the Smoothie showed up this afternoon. I expect the motor at any time. There is a picture on the Smoothie showing it’s hookup. Are there any glaring pitfalls, wiring all this stuff up? If so, explain it like you were trying to tell it to a chimpanzee monkey.
I have a good steel ammo can to charge the LiPo in. Also a fire extinguisher handy would be a good idea I am thinking.
100 watts of power might just be enough to raise the hairs on my head!!! WoooHoooo!!!!03/29/2008 at 1:24 am #45565
Be careful with your amo can, it sounds conductive. Lipos are dangerous in two ways: shorting the battery and improper use of a charger. Lipos do not kill people, people kill people 😆 I have never had a problem with a battery. If charging indoors I use a glass bowl, outdoors no worries. Soldering small connections can be tricky. I would solder connectors to the timer so that it can be easily removed or replaced. Have you chosen a connector yet? I like the MP Jet pin connectors.
They are over kill on low power systems but you will find that as your collection of batteries and models grow you will need a system that allows you to interchange components. Mine changed many times before settling on MJ21021. You will need good soldering skills. If you do not have them just practice untill you do. Keep us posted.04/01/2008 at 6:03 pm #45566
My motor arrived today. I am shocked at the size of it. I was expecting something much larger. It weighs in at 25.5 grams with wires and connectors on it. I am not sure what connectors these are, but perhaps I should try to stick with them for the rest of the connections, except perhaps the battery connection to keep things simple. I should be able to find them locally.
The Smoothie instructions state that connectors can be used to plug into the back of the thing. Is that what you [Jim] have done,or do you just solder right to the Smoothie? I am leery of getting a soldering iron close to those printed circuits.
It appears to be fairly straightforward to wire up, looking at the Smoothie instructions.
I will get it hooked up and run on the bench before I put it into the plane.
Question, [it may sound dumb], does the LiPo pack need plenty, plenty venilation mounted on the plane to keep the temps down? I was going to enlarge the pylon to mount the battery pack securely, and protect it,but was wondering if I needed to make venilation holes to keep the temps down.04/02/2008 at 3:23 am #45567
Dohrm, I would suggest that you use the connections on the Smoothie. The one that I had worked fine until I tried to solder connections for a servo and your fears became reality for me. It went up in smoke! Lipos when pushed to extreems will get a little warm, but not enough to worry about. The best advice that I can give about battery placement is this:
Place the battery in a position so that if and when it gets ejected form the model it does not destroy the model. Mr. Groth tried to teach me this early on but as usual I had to learn it the hard way. Do not put the battery behind anything that you are not prepared to rebuild. Notice the battery placement on the F1Q earlier in this string. Every electric model that I build has the battery in a position to be easily ejected. Thanks Chuck.04/07/2008 at 8:28 pm #45568
Sitting here looking at my components, I just realized that the Smoothie for the brushless motor does not appear to have the hot wire dt function. What are you fellows doing for a quick dt? I guess I will have to go to a fuse, or put in a servo. I don’t like the idea of this thing getting any heavier, but a quick dt might save the day while I am trimming it out.
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