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Model Forum / Radio Controlled / Air Models / May 2004Newbie question
I bet this is FAQ stuff, so could someone point me to the direction of that? (Couldn't find it with quick googling) I used to build those balsa&paper kits as a kid, and mysteriously I just got an inspiration again after seeing some RC airplanes in a window of a store. However, I want to build my own. First I'd like to complete my very own desing with balsa and paper. After that I'd like to create one with styrofoam fuselage, balsa wings and hardened with carbon fiber cloth. This will probably be more of a proto model rather than actually well flying airplane. After this, I'd like to improve on previous model and power it with an electrical AC motor. This would be a free flighter. Finally, my plan would be to desing fully controllable plane from scratch. This probably seems way too ambitious, but I am in no hurry. I'm not so much excited about flying the device itself. My primary goal is to learn more about aerodynamics. And then to the inane questions... (Please point me to the FAQ ;)) 1. Is there free available software to simulate aerodynamics properties of complete structures. For example, I would model the whole thing in some cad or 3d studio max or whatever, and import it to the aerodynamics software. Which in turn would run some kind of virtual airtunnel for it, and finally tell me that my desing flies like a rock :) Ok, I don't understand much about aerodynamics, so I don't actually know what to expect from such software. Some kind of visual interpretation of data on lift, drag and so on would be helpfull while I'm learning the ropes. Reasonably priced software (sub 100 euros) would sound good too. Once I get more serious about this project I might consider more expensive solutions. What do the pro's use? 2. Is it theoretically possible to have such software that would also simulate the internal effects of the models engine(s) to the dynamics? Say, I would have an engine under both wings, propellers positioned partially in the front of the wings. Would it be possible to simulate how the engines airflows affect the environmental airflow? How about the effects on structural tension because of partial obscuration of the airflow from the engine (engine trying to bend it's strut because of nonuniformal distribution of the delivered power from the propeller) 3. How do I work with carbon fiber? My understanding is that I can coat something with carbon fiber cloth and somehow harden it... What is the procedure for hardening the sheet? Does it shrink(or grow) while hardening? 4. How to work with styrofoam? What kind of tools are needed to easily craft it? 5. What should I expect to pay for a crappy&cheap servo kit + radio control for a plane? Is there such ready made kits, or am I looking forward to also making the electronics design? 6. Is there some thumb of rule for selecting an electrical motor? At this point, my plan for getting an electrical motor(s) for the first powered proto is just to trial an error. I am an electrical automation assembler by education, and a software integrator by trade. I also know how to use different brands of 3d modelling softwares. I can do basic electrical elngineering and have close friends who can work with microelectronics. I can also program in several languages, so creating my own approximation software from physics theories is an option too. (Once I get an idea at what I am throwing myself at) So, thanks for reading. I'm eagerly waiting for any answers. This is my first post, and to be honest, I haven't lurked enough here to know if this proper group for my post. If not, please point me to the right direction. > I bet this is FAQ stuff, so could someone point me to the direction of that? > (Couldn't find it with quick googling) [quoted text clipped - 60 lines] > first post, and to be honest, I haven't lurked enough here to know if this > proper group for my post. If not, please point me to the right direction. Your destination here is understood, and teh first post of call should be www.ezonemag.com. Register, and visit the varous fora of relevance. A lot of plans and stick and tissue and other stuff in the builders firum. Details about aerodynamics and so on the the modelling science forum. Info on foamn in the foamies and parkflyer, lots of stuff on motors and batteries etc in the appropiate fora. Its all hosted under rcgroups so ther is overlap into other displines like gas/glo and boats. Its moderated so the signal to noise ratio is far higher than here. Off you go, and have fun :-) Hi Lassi, I have a strong hunch that you're from Finland, right? 'Lassi','nokia'? A good Finnish forum: http://lennokit.net Electric flight FAQ: http://www.ezonemag.com/pages/efaq.htm Motor selection software: http://www.motocalc.com David Theunissen's site, Fly electric: http://www.flyelectric.ukgateway.net/ David must have Dutch ancestry, "Theunissen" is a Dutch name. Links and internet magazine: http://members.aol.com/kmyersefo/ Building your own high-torque electric motors, don't let the picture of yours truly frighten you ;-) http://www.yahoogroups.com/group/lrk-torquemax/ Profile software: http://www.profili2.com/ Met vriendelijke groet ;-) Ron van Sommeren near Nijmegen, the Netherlands http://home.hetnet.nl/~ronvans/ electric fly-in -- Anti-Spam: my address must be modified. > I bet this is FAQ stuff, so could someone point me to the direction of that? > (Couldn't find it with quick googling) [quoted text clipped - 60 lines] > first post, and to be honest, I haven't lurked enough here to know if this > proper group for my post. If not, please point me to the right direction. > I bet this is FAQ stuff, so could someone point me to the direction of that? > (Couldn't find it with quick googling) [quoted text clipped - 14 lines] > > And then to the inane questions... (Please point me to the FAQ ;)) You've already got some good responses; I'll try to supplement them here... > 1. Is there free available software to simulate aerodynamics properties of > complete structures. For example, I would model the whole thing in some cad [quoted text clipped - 6 lines] > (sub 100 euros) would sound good too. Once I get more serious about this > project I might consider more expensive solutions. What do the pro's use? Not that I'm aware of - I think most modelers use basic rules of thumb and equations to determine the proper design. > 2. Is it theoretically possible to have such software that would also > simulate the internal effects of the models engine(s) to the dynamics? Say, [quoted text clipped - 4 lines] > engine (engine trying to bend it's strut because of nonuniformal > distribution of the delivered power from the propeller) Again, not that I'm aware of (but unless you're building extremely huge or extremely flimsy, shouldn't be an issue!) > 3. How do I work with carbon fiber? My understanding is that I can coat > something with carbon fiber cloth and somehow harden it... What is the > procedure for hardening the sheet? Does it shrink(or grow) while hardening? Carbon fiber rods are sometimes imbedded in foam parts to stiffen them - they're just glued in with epoxy in that case. You may find fiberglass is more reasonable to work with and will work fine in your application. It is laminated on a model with thin epoxy. Fiberglass will not change shape while curing. > 4. How to work with styrofoam? What kind of tools are needed to easily craft > it? Just about anything will work on styrofoam. A hot-wire setup seems to be the most common (a hot wire held in a bow passed through foam can make a long, straight cut). Sandpaper is also a must. > 5. What should I expect to pay for a crappy&cheap servo kit + radio control > for a plane? Is there such ready made kits, or am I looking forward to also > making the electronics design? I think the Hitec Laser 4 FM with 4 servos and receiver can be found for around US$125. I don't know about you, but there is no way I'd tackle making my own radio gear! > 6. Is there some thumb of rule for selecting an electrical motor? At this > point, my plan for getting an electrical motor(s) for the first powered > proto is just to trial an error. Several - selecting the right motor may be one of the bigger challenges of building. Motocalc, as was mentioned, will go a long way toward selecting the right motor, but I don't believe it has all available motors listed in its database (couldn't find my AXI's anywhere). The process goes something like this: 1. Determine what the all-up-weight of your finished, ready to fly model will be (a bit of a challenge, when you don't have the MOTOR!) 2. Determine how you'd like to fly it (such as sedately, on 55Watts per pound, or very aerobatic, at about 100Watts per pound) 3. Watts per pound X total weight of aircraft = total needed Watts. 4. Now, just find the smallest motor, battery and prop combination that can deliver that. In most cases, you'll find that the motor manufacturers will provide Amp draw at various voltages with suitable props for that motor. Be sure that your speed controller and batteries can handle the current drain. And there are variables even within that - you can increase the cell count of your battery pack for more voltage and more power, at the cost of duration. Enjoy! > I am an electrical automation assembler by education, and a software > integrator by trade. I also know how to use different brands of 3d modelling [quoted text clipped - 6 lines] > first post, and to be honest, I haven't lurked enough here to know if this > proper group for my post. If not, please point me to the right direction. Running a plane with an AC motor seems an interesting challenge - amy particular reason for avoiding the DC route? While I am not that cluey on motors, I would have thought any adantage of using an AC supply would be nullified by the need to design, build, and install an inverter. David - who is always in wonder at the (sometimes strange) things people want to do, but admires their willingness to take on a challenge > ....After this, I'd like to improve on previous model and power it > with an electrical AC motor. ... I can do basic electrical elngineering and > have close friends who > can work with microelectronics. >Running a plane with an AC motor seems an interesting challenge AC? That's gonna be one hell of a long drop cord! Dr.1 Driver "There's a Hun in the sun!" Any brushless, sensorless motor is an AC motor, with the speed controller being the 3-phase inverter that keeps the AC in step with the motor position. No brushes, no moving coils, nothing to wear out. (I haven't flown mine yet, so my current enthusiasm may change in the face of reality.) -- Mike Norton > >Running a plane with an AC motor seems an interesting challenge > > AC? That's gonna be one hell of a long drop cord! > Dr.1 Driver > "There's a Hun in the sun!" > No brushes, no moving coils, nothing to wear out. (I haven't flown mine > yet, so my current enthusiasm may change in the face of reality.) It won't Mike, no worries :-) Groeten ;-) Ron van Sommeren diy brushless e-motor building group: http://www.yahoogroups.com/group/lrk-torquemax electric fly-in, Nijmegen, the Netherlands http://home.hetnet.nl/~ronvans/ >>Running a plane with an AC motor seems an interesting challenge > > AC? That's gonna be one hell of a long drop cord! All electtic motors are AC three phase in reality. Brushes and commutators are a crude way of generating it. Brushless motors are true AC motors without brushes or commutators - the commutation process is dne by a piece of electronics that generates a synchronous 3 phase waveform to feed to the motors. > Dr.1 Driver > "There's a Hun in the sun!" Ahhh well I have learnt something new again - in my day brushed motors running on DC applied DC to the commutator segments in turn as the commutor rotated - I have had look at some of those little Mabuchi motors used in slot cars and lo and behold no matter how hard I looked I couldn't find any inverter electronics. Must be very well hidden or so small these old eyes of mine just couldn't see them. Or if they are somehow fed to the motor from the speed controller I am curious about how these electronic wizards of today xmit those three phases to the motor in my Slow Stick thru only 2 wires - very clever indeed. Also, in my day we called a motor a DC motor if it worked when you applied DC to it, and called it an AC motor when you applied AC to it. I just can't keep up with this modern word sometimes - sigh David - who seems to be forgetting a lot of the stuff he used to know about, but is getting a bit bloody sarcastic (but just in fun) > All electtic motors are AC three phase in reality. > [quoted text clipped - 5 lines] > > Dr.1 Driver > > "There's a Hun in the sun!" >>The Natural Philosopher wrote: >> [quoted text clipped - 7 lines] > > Dr.1 Driver > > "There's a Hun in the sun!" > Ahhh well I have learnt something new again - in my day brushed motors > running on DC applied DC to the commutator segments in turn as the commutor [quoted text clipped - 13 lines] > David - who seems to be forgetting a lot of the stuff he used to know > about, but is getting a bit bloody sarcastic (but just in fun) While in practicality you are correct, he was technically correct in identifying brushed DC motors as AC motors internally. Every 180 degrees the current changes direction in each set of windings in a brushed DC motor. That's why a series wound or compound wound DC motor will run on AC current and is called a universal motor. -- Dave Thompson Ah yes, I got some kind of a bran fart. What I really ment to say was DC motor. But as Mike Norton points out deeper in the thread, AC motors have bunch of advantages. Building the "chopper circuit" is not very complex... Now that you mentioned, it would be pretty nice to use an AC motor =) (What is the proper english term for the circuit that chops DC and enables one to derive AC out of it? :)) I might also use this post to thank everyone who has answered. You have been most helpfull :) The forums you pointed for me have vast amounts of information I can delve into :) Oh yeah, yes I am a Finn :) > Running a plane with an AC motor seems an interesting challenge - amy > particular reason for avoiding the DC route? While I am not that cluey on [quoted text clipped - 8 lines] > > have close friends who > > can work with microelectronics. <snip > (What is the proper english term for the circuit that chops DC and enables > one to derive AC out of it? :)) I think the device you refer to is called an inverter. Best of luck with your experiments, after all it's the cranks which make the wheels turn. <VBG> Malcolm If you really want to fly R/C, make it easy on yourself and get a Hobbico Nexstar from Towerhobbies. Join AMA, Join a Club, find an instructor pilot, and learn to fly. After that, have a ball playing around with all the esoteric ideas. > I bet this is FAQ stuff, so could someone point me to the direction of that? > (Couldn't find it with quick googling) [quoted text clipped - 60 lines] > first post, and to be honest, I haven't lurked enough here to know if this > proper group for my post. If not, please point me to the right direction. I fully understand this. I'm just a bit weird person. As I said, I'm not all that excited about the flying, but want to learn aerodynamics and build it myself :) Besides, I expect to crash it horribly on the first try anyway. Requiring complete rebuild. And then again. And again untill I get it :) Go figure, I also craft fishing flies because I think it's fun. I don't even own a fly fishing rod :) > If you really want to fly R/C, make it easy on yourself and get a Hobbico > Nexstar from Towerhobbies. Join AMA, Join a Club, find an instructor pilot, > and learn to fly. After that, have a ball playing around with all the > esoteric ideas. <snip> |
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