Okay, here goes-
I’m formulating in this twisted head of mine an overly-ambitous, too-complicated project that I have no hope of completing- you know, same ol’ story. For details on what exactly this hair-brained sceme of mine is, check out the link in my signiture. (See below). Oh, and it’s in 1:72.
What I need help on (other than the fact of space and cost), and adding to the complexity of the project, I thought, “hey, with 8 props and so much room, why not moterize it!?” (I attribute my idea to Swanny. Any patents on your idea?) There’s just on problem- the only thing I know about electric is that you need a closed circuit to make it work! [D)]
That’s were you come in…
This is what I know for sure- I need 8 motors total (Yee ha), and a battery that will fit inside the fuselage easily, and provide enough juice to last a reletively long time. That, and the motors need to fit in the nallaces of the kit (Most likely the new Revell of Germany Ju 290). I’m not doing any lighting or anything else, so, if possible, I’d like to keep the wiring simple.
What I need from you is, basically, everything else. What kind of battery would be best, how is the best way to wire this situation, what would be the best motors to use (I’m looking at pager motors), and God knows what else! Feel free to put in any info of your own, any tips, and anything calling me absolutly crazy for trying this! So, that’s it, and thanks for sticking with this novel to the end.
[(-D]
Batteries + Motors = Short battery life.
There’s simply no way around that one. unless you find a means to engineer a miniature nuclear fuel cell that generates no heat I think your battery desires will come up short in production. Even with lighting, which when compared to motors use very little current draw, one has to change out batteries fairly often in most cases.
Is there a chance of doing the kit in a diorama and hard wiring it to a 115v transformer that plugs into the wall? That’s how I run my lighted F-117A and how I would want to to anything with motors in it as well if I were to go that route.
I know this probably isn’t helping you to find a solution to the problem of power, but hopefully it will offer a little more insight into what you can and should not reasonably expect from miniature electronics.
Bri~
Lucien,
I have seen a few solutions - but they don’t involve a battery in the fuselage as you requested.
If you want to do an “in-flight” model you could put it on a pedistal and run wiring through a pedistal to a much larger (replacable) battery in a base.
Or if you are going to make it an “on-the-ground” plane with engines running (and your a bit ambitious) Check out the May 2002 issue of FSM. There is an article showing how to wire a plane up through the landing gear - Its a gorgeous Lockheed Constellation - very impressive. This plane was wired to the gills, but you wouldn’t have to get that complicated. Again - it involves a battery in a display base - or it could, as Bri~ mentioned…a transformer to an AC source.
If you want to make it an “in-flight” model hanging from the ceiling… hmmmmm… I’ll have to put on my creativity cap for that one… ( ! ) You could wire it to a ceiling lighting fixture and use standard 12-2 copper electrical wire to power it and suspend it !
Good thing it’s not a Catalina. A water landing would be really interesting.
Good luck man !
Chris
Quite an undertaking there Lucien. Can’t wait to see pics of your progress. reminds me that I have a Zwilling on the shelf that needs some attention. Good luck with the project. Hopefully it will be one of those that is not taken so seriously, and ends up coming out the best!
Can you give me a source for those pager motors you’re looking at? I’m doing a Dornier Do17 that I might want to motorize (I’ve been “Swannied” also).
Stay with the project man. It’s gonna be a great one!
stinger
As I said before, this idea is very far in the future. (Did I say that before?..) As of now, I don’t have the resources or the cash to even start it yet. But I will do it sometime. I’m just getting a bunch of specifics out of the way first.
About battery life- forget about a long life. I just need someting that will be strong enough, but not so strong it blows the motors out. I was thinking 9 volt.
About the pager motors- I have no idea right now what I’m going to use yet.
Mike,
The power of the battery is dependant on the size of the motors you’ll be using. Some will turn with as little as 1.5v DC and perhaps even less. You have to remember, the motors will be turning props that offer basically no resistance so power shouldn’t be a factor. You’ll also likely want to keep the rpm’s down to a reasonable level so that vibrations don’t shake the model apart, and/or damage the props. Also, if they are spinning too fast, you won’t be able to see them at all.
Just a few more things to look into…
Brian~
That’s exactly why I posted this topic!
[:D][:D]
If I do get 8 1.5 volt motors, would a 9 volt work for that? That’s kind of what I was looking at.
It depends on how you wire things. If you wired them all in series, then you’d need a coltage supply equal to their individual voltage multiplied by the number of motors:
8 motors X 1.5 volts = 12 volts required to run at full capacity.
However, if you wire them in parallel, you’ll only need 1.5 volts but a higher amperage to push them all. (at least I think that’s how it works!)
Again, I’d look for the smallest, most efficient, lowest voltage motors you can find to fit your application. Now when you say 8 motors, are you planning on working out a system of 4 counter rotating props like on the Russian “Bear”?? I don’t know how you’d do it but I imagine with enough planing it could work well…
No, uilleann, when I say 8 motors, I mean 8 motors coupled to 8 seperate props in 8 seperate nallaces! Did you see what I had in mind to put them in? If not, check out the link in my signiature.
Did I say that before? [sigh]
About wiring, I admit that a series curcuit would be much more convenient in this situation like this, but a parallel would be more efficient. How many amps does the average battery put out? (I know I’m stuck on batteries, and you have offered so many helpful alternatives, and I acknowledge that. (Thanks!) It’s just that one, this project is big enough without having to do a diorama on top of that, and two-
I forget.) If I could get away with a small battery, even if it don’t last too long, by wiring in parallel, that would be great. But, once again, I’m just worried about the amperage.
Could you run eight 1.5 volt motors (wired in series) off a 9 volt battery, and just have the motors run slower? Or would a situation like this only suck the juice of the battery(s) even faster?
And yes, I have (in my head) tried to find a way to motorize contra-props (Like the Bear). As of yet, I am unsuccessful in finding a solution.
I’m still trying to figure out Swanny’s post.
WOW - uh…hmmm…well…OK…first thing to do is run to the local pharmacy and stock up on a healthy dose of prozac. THAT THING LOOKS HUGE! [:O]
OK, sorry about my little outburst there…[^] you’re basically on the right track. The thing to remember, is that Voltage is the number of electrons flowing past a point in a given time in a circuit, and that Amperage is how hard those little buggers are pushing to get there. If you have eight engined, they’re going to require eight engines worth of push to drive them regardless of the supply voltage you end up with.
Small batteries just aren’t good at supplying this type of current for long or even short periods. You may get an hour or even several hours worth of turning from a cell, but sooner than later it will die and need to be replaced. I admit I don’t know what the average output of say a 9v battery is in terms of amperage as my multi-meter doesn’t measure current flow…just voltage etc.
Second thing to think about is expense. Have you priced 9v batteries lately? Most of the better brands can run close to $5.00 each. You might need to think about replacing the batt. once or possibly even more each week depending on how often you operate the model. Another consideration is corosion. It’ doesn’t always happen, but in my experience, 9v’s tend to be the worst at it. If you have a DC cell snuggled up in a compartment of the model and it were to leak, how badly could that affect the rest of the build and would it be something you’d be able to spot right away and fix/clean up?
For my F-117A I used an external power source for two reasons: First, I could connect/dis-connect it at will and it was as simple as unplugging one connector. Second the power never died slowly over time and always supplied the same voltage period. You can see some images of what I did here: http://www.finescale.com/fsm/community/forum/topic.asp?TOPIC_ID=16899
You could easily hook something like this into a large model and recess it (sink it down just below surface leven) and make a removeable panel to allow for connection to the power source and yet it could be covered when not used and would look flush and smooth. Very likely no one but you would even know it was there unless it was plugged in. You also wouldn’t have to worry about the extra weight a battery might add on top of the motors and all the extra scratch building you’d be adding.
I really don’t have anything against batteries, but for static display models I just don’t find that they fit the bill most of the time for motorization or lighting is all. If you’re still heart set on the battery idea, I’d suggest grabbing a good quality multi-meter from the local Radio Shack etc. and using it to test the amperage of batteries, then start looking for motors that might suit it. You’d also want to test any wall socket type transformers this way too however as their rated power and amperage might not be exactly what you’re getting out of it’s little plug.
I do hope that some of this is helpful for you.
Brian
Okay, how 'bout this-
What if I wire the two banks of four engines seperatly (two batteries, switches, and whatnot)? How would that relate to battery usage/comsumtion? Or, beyond that, does anyone have any opinions on that?
Ummm…apart from having to worry about twice the number of solder joints, broken circuits and weight/strage space needed for the batteries, it would work out great. [;)] You would of course have a battery reserve (think of it like a reservoir) twice that of just a single battery, but again, 9v are not known for exceptional long life in any case. The old motorized B-17 kit I built years back used several D cell batteries in the bomb bay (I think) and even with that much ‘juice’ storage the four motors would still run down after a relatively short while.
The simpler you can go the better I would think - especially with eight engines. What you’re asking can be done, but it seems like it would be frought with problems from the get go. Another consideration if you’re heart set on using batteries is where would you mount them in the kit and how easy would they be to change often? If they sit too far back of the a/c center of gravity you’ll have a permanent tail sitter! Too far forward and a perpetual nose dive. Just some other things you’ll want to watch for as you start the build.
B~
Mind if I jump in here?
Your pager motors are 1.5 volts, and the current drawn will depend on how the 8 are wired up. Lucien, you mentioned series witing would be convenient for you, so if you put the 4 port motors in series, and the 4 starboard motors in another series, that would be 6 volts per series.
This is now a reasonable voltage for a battery or adapter module.
Put your two series in parallel, and you have a requirement for 6 volts @ the current equivalent of 2 motors. This would be how I would do it to make a circuit at a reasonable voltage with minimum current draw.
As to battery capacity, this depends on the requirements of the motor, and is measured in amp-hours. Even a tiiny battery can supply a large amount of current, but for a very brief time. The same battery will supply less current for a longer time.
You need to mock up your motor circuit, hook up an ammeter, and measure the current drawn. Multiply this by the number of hours you want between charges or replacements to determine how big a battery you need.
The above exercise is academic however because I expect you will not find one large enough, and the comments from others about replacing batteries are well founded. I recommend using the information from the ammeter to get an AC adapter that will deliver at least the minimum amount of current (bigger is OK) and forget the battery.
Run your wires out of the model somehow, as suggested by others, and connect the adapter. You can also visit hobby shops specializing in radio control where they sell miniature connectors. These could be used to plug your model into the base or whatever to make it portable.
If you are fixated on batteries they also sell a range of high capacity types for electric R/C planes, plus the chargers to go with them.
Enjoy!
Bruce
Yes, I am fixated on batteries, and I don’t mind about battery life for the reason that whatever I do, I plan to get a rechargeable one. Other than that, you have given me a lot to think about, to say the least! [(-D]
Have you found a source for pager motors yet. I bought some to motorize my AirWolf model and had difficulty getting the ballest off without cutting the shaft to short that I couldn’t use a couple of them.
If you find a source that doesn’t have a ballest on the end, let me know please.
Don [alien]
I haven’t thought of using R/C connectors before, those would be great I would think! MUCH smaller than the 1/16" mini-phono plugs I was using before. You could hide them extremely easily I would think.
As for the pager motors, I seem to recall seeing an article in a book about modeling and lighting and dioramas etc. (probably published by Fine Scale) that the author had a similar problem with the shafts and the weights forcing them to be cut too short.
Have you check ed with your local electronics supply store for mini motors? Maybe Edmund Scientific? Take a look at these. LOTS of possible applications:
http://scientificsonline.com/product.asp?pn=3117400&bhcd2=1083436853
http://scientificsonline.com/product.asp?pn=3035128&bhcd2=1083436674
http://scientificsonline.com/product.asp?cs=p&pn=3082264&bhcd2=1083436711
http://scientificsonline.com/product.asp?pn=3037590&bhcd2=1083436761
http://scientificsonline.com/product.asp?cs=p&pn=3053520&bhcd2=1083436783
I wish I could transfer 1 and a half years of Navy electronics schooling in a post. Not easy. So I’ll suggest going to Radio Shack. They have motors and other parts of all sizes. As a short cut I’d say Bruce (B. LeCren) has you pointed in the right direction. I’d split the motors into 2 equal series circuit’s run in parallel. And using R/C rechargable batteries is the best thing going (let’s face it, you won’t run it full time anyways).
Just thinking about this post, and replying to it has inspired me to motorize my Monogram 1/32 F3F-3 that I wasn’t happy with anyways. It’ll take some work but it should be impressive.
You could have the landing gear bays pop open, and reveal the 9v’s. And you could have two of them, so they wouldn’t use as much battery power.
