apulmax69

I am in the process of building my own design of (draganflyer)
its a 4 motor/rotor flying saucer simplest way to describe it is like an X with a rotor on each end



I want to be able to control lift that is all for motors equal in speed using the throttle lever on a 4 ch transmitter
then forward motion by increasing the rear motor and decreasing the front at the same time
I want to control roll by increasing the left motor and decreasing the right equally as to keep altitude
and control yaw by slowing down 2 opposing rotors . I know this looks complicated but I am sure there is a simple solution
This can be done by custom electronics but I want to build a prototype first just by plugging bit together.
If this cant be done is there a specialist unit or transmitter that cant mix up to 4 channels together for each function on a 4 channel transmitter. Sorry if the explaination is a bit vague, not my strong point. Thank you in advance. Mark

Spaceclam

i did the same thing for a school prodject. If you have a nice computer radio, the mixing should be done in there because it will save you a bunch of money. however, if you do not have access to the four channel tx, you will have to go the vtail route. cheap ones will not work here. the only one that i know is accurate enough to work and has adjustable atvs on all output channels with channel offset is the veetail omni. check it out at www.veetail.com
the only real issue there is the fact that it costs $53 for one of them and it would require three of them to do it. here's the setup



you havea 4 channel receiver. you also have vtail mixers that i will label #1,#2, #3,

plug the slave of #1 into channel 1
plug the slave of #2 into channel 2
Plug the master of #3 into channel 3
plug the slave of #3 into channel 4
plug the master of #1 into one of the outputs of #3
plug the master of #2 into the remaining output of #3.


that will give you throtle control, and the aileron/elevator will do the correct thing by slowing down one motor and speeding up the other. however, for this prodject you will need counter-rotating props to save the weight of a thruster. i know where you can get these. that setup will also allow you to control aileron, and even rudder. the rudder will work by increasing the speed of one set of motors and slowing down the other to keep the thrust wehre it is but one pair os going faster so the torque will spin the model. you will have to have a setup somewhta like this. my contraption actually flies, so i am not leading you with theories. if you are interreested i can tell you where to get some of the critical components and whta to avoid

apulmax69

Hi,

Thank you for your response, yes that is exactly what I am building, looks like I am using the same motor/gearbox combined as you, but the props I am using are foam ones from a twin rotor heli as 2 rotors have to spin opposite directions to stop the torque spin. I am happy to buy a radio if it will do the job, not too sure if the sanwa rd6000 or futaba ff6xs will work, possibly the ff9 will but at that price i would expect it to.

I would love any info you could provide as this will save me time going up the wrong route. I have built the centre pod out of balsa soaked in superglue as I dont want to build anything too complex if i have to cut bits off here and there and add bits etc. the 4 main spans are carbon fibre tubing. The battery is a lithium polymer 1020mh 11.1v. I have also bought 2 gyros for stability in the roll and forward/backward planes.
I can buy a 4 channel sanwa transmitter for £30uk about $45. not too sure which way to go

apulmax69

Ok, I have let my senses take over and I bought a Futaba 9cap/9chp transmitter which the store demonstrated it working on servos, using the 4 squash plate heli setting with additional mixes for the rudder, so in theory it should work with the speed controllers. Any more info tips etc I would greatly appreciate - Mark

Spaceclam

i did a mixing thing on my 8u that does everything but rudder control. however, i have now bought a couple digital 14 bit vtails (to insure i don't have the accuracy problem i did before) to line together. if you would like, i can tell you how to di it with vtails that will allow you to control all 4 axis.

Spaceclam

i jsut got some of the omni mixers from www.veetail.com they are great gadjets. true 14 bit accuracy. i installed them and flew them in my 4 rotor thingamabob and they work great. however, all they sell are the omnis and for the correct setup (control of aileron elevator throttle and rudder) it will require 3 mixers and it will cost $168 with shipping. they are great. however, don't attempt to do it without the rudder. here's why. personally, i can't get the motors so absolutely perfectly strait up that the thing will not yaw a bit. it will turn on you. within 5 seconds it will probably start. you will have to land everh time that happens. one more thing. you say you need to mix speed controllers. make sure your speed controllers are very perportional. those cheaper 16 step controllers simply will not do. the hitec 1010 speed controls were great, but they discontinued them. you want a speed controller with individual bec switches, and you at least want a motor arming switch for each motor. you may be able to find the hitec 1010 controls somewhere, they were great. only $20. the gp electrifly ones cost abotu that, but they have neither an arming switch nor a bec switch.

littlefreak

I dont know much about RCs if anything realy. But im a pilot so I know alot about areonotics and Im great with computers and programing. I saw the Draganfly in a airplane magazine and wanted it.. But as you know its 800 dolars money i dont have. So I wanted to build one. I read your posts and wanted to know what you think would be the cheapest way for a novice to go about making something like this? Could I get a tranmitter and a receiver that i could just program the transmitter to do certain things when i move certains switchs?? (for example tell it when I move the stick left lower the left motor speed and raise the rights?)

Spaceclam

that is what i did, except it flies with 1 motor completely forward in a cross shape, not in an x shape. it would require a LOT more mixers to do it that way i mixed the controls on my futaba 8u but it did not have enough programable mixers to allow for rudder control. to be really honest, it will cost you about the same to make on as it will to buy one. because of the lack of mixers (evne on the 8u) i had to use vtail mixers. with that im mind, i have about $550 in the flyer itself and another $200 in radio so it adds up to about the same. if you want to make one, i will be happy to help with sugestions and such. if you have any questions you can ask me if you wish, i would be happy to help. here's a pic of mine flying

Spaceclam

and another

littlefreak

OK now then let me see if i can first fingure out what i need for this..
4 ch transmitter & receiver (4ch role, pitch, yaw, eleivation.. right?)
3 veetails
4 motors and gears
4 props
and a frame..

am i missing anything there?

And you sure there isnt any programable transmitters that will let me do all 4 things? because then i could least save that for anougher project instead of having to take apart my draganfly to do anougher project.

littlefreak

Does it have to be a realy complicated transmitter or can i just be any old simple 4 ch transmitter?
[link=http://www.hobbyhorse.com/laser_radios.shtml]http://www.hobbyhorse.com/laser_radios.shtml [/link] will that one work?

Spaceclam

well, yes the transmitter will work. however, you will have to turn all the rates all the way down and it will still be way too hard to control. with my 8u i have it set up so that not only are my atvs down to 30% (the minimum) but i also mix the channels onto themselves with a negative value. i have set it to mix -70% onto the channel itself giving me only about 9% travel and that is plenty. also, i have that set of mixers designed to turn of when i flip up my trainer switch and another set with a mix of -60% to come in to give me more control in a big gust of wind or something. you can do without that but it is sure nice to have. Also, you will need to get speed controllers as well. you did not list it in your list so i decided to be sure, as you may be new to electrics. you will need 4 of those. the great planes one will do, but you should put a motor switch on so you can have the bec on and the motors disarmed. you need good ones though because the cheap ones have too few steps to be accurate enough to control the model. propwise you will need to find a good counterrotating set that will work for your size model. the only ones i know of are the ones i use 10x4.5 set of cw and ccw props, one of each for $4 at toddsmodels.com, and the draganflyer props from spectrolutions.com. they are only designed to spin at about 1000 rpms max. they are very flimsy and undercambered so if you go much above that the blades will not provide much more lift as the edges go into negative pitch. if you want to make a smaller one than mine by all means go ahead, they will work fine. if you want to go biger, there is a cf set that comes out of germany that come from braun modellbau at http://braunmod.de/eprodukte.htm they are very efficient and very expensive. you can find these at northeast sailplanes i believe but i have heard far too much flack about them to even considering a purchase. the props are about $30 for a set of two so i would stay away if i were you. a word of advice. the larger props you use the more responsive it will be as the rotor disk loading will be lower. you want the lowest pitch blades to reduce blade stalling, and larger blades spinning at lower rpms are better for a project like this. as far as veetail mixers (or elevon mixers as they are sometimes known) the cheap ones will not do either. they have very poor resolution and the centerpoint changes every time. the only ones that worked for me are the ones from www.veetail.com. they are called the omnis and retail for about $55 apice. i tried the wattage mixers first though. they are the same as the gws ones and the graupner ones etc. they only have like 16 steps. by now i am sure you realize that you are undertaking an expensive endeavor. the only reason i was able to complete such a thing was because my dad helped fund me, this being a school project. i would be happy to help in any way. let me know if you have a question.
cheers

littlefreak

Ok i was planning on getting actual draganflyer replacement props which are all 4 for 20 bucks. The speedcontrolers they would be the things that turn a servo transmition into a electic motor speed transmition... so basicly they contol howmuch electricity goes to the motor. ok.... And as for stableness I dont need a solid rock I probly will fly it indoor more then out. So ill go with a cheap transmitter... Also being curious... You thing insake of money.. This wont be efficent but a 3 speed gear box instead of those vtail things... and i would servos to control what gear ratio its on. Ive done a bit with robots never plains... And i know i can have a gear box do that.. I dont care about stablity I can fly around. So all it has to do is fly(duh) and go forward backwards and turn. If I wanted to realy fly something serious I go flying myself.

littlefreak

I was also thinking about doing a 3 proped one instead of 4... This be done with 1 in front and 2 sides.

Spaceclam

if you are going to fly it indoors than you need to have more stability than you require outdoors unless you don't care about your model or furnature. as far as the gear thing goes, i would not recomend it. you need precice control. that will be anything but precice. a perfect example of this is the veetails i got at first had 16 step resolution and it was unflyable. simply too corse. doing it the gear way will probably cost more becuase you will have to make them custon, weigh a lot more and it will have less possible steps than even the far too imprecice veetails i started out with before. you are welcomed to try but don't be surprised. as a mater of fact, speaking abotu accuracy, i had to remove my throttle ratched because it has only 27 steps and i could not find that sweet throttle spot. as far as the 3 motors go you can"t have only 1 on the front and 2 on the sides because the throttle from that one would flip it over. that would be like putting a rocket engine facing downward on the tip of one wing (on your most complicated rc plane) and not the other. that means you would have to put the motors in a tripod position to correct that problem, but then, how do you cancel out torque with an uneven number of motors? the only answer is to put thrusters wich are laggy and will weigh a lot more on top of less rotor disk space. not to mention, you would have to coordinate the thrusters with the movements, and you would have to have two motors speed up just a little bit and the opposing one slow down considerably more. if you go for the cheapy radio, to get it to mix correctly it will require a lot more mixers (remember you need the expensive ones because the cheap ones are too corse for controlled flight) and it will cost you a fortune, far more than it will cost to get the draganflyer. you see how complicated this is getting with all the problems that have no good solution and what not. you kinda have to use 2 motors and put them on gimbals (like the guy who i got the original inspiration to od this from) or use 4 rotors becuase, being an even number you can opperate them in pairs making life a lot easier. doing three motors has no benifit and has a whole slew of problems. like i said yo uare welcomed to try but i probably won't be able to help any.

littlefreak

i might be biting off more then i can chew here but im thing about giving it a try... so heres what im gonna get..
3 veetails(omnis) - $165
Receiver and transmiter pack - $127
Props - $20

thats $312

I still need motors and motors controls . I just want the least minimal for this nothing to pricey. Any suggestions?

Spaceclam

you are not biting off more than you can chew. i just turned 14 and i managed to get it to fly while i was still 13. just a couple things. don't order the props yet, and make sure that you get at least a 4 channel receiver and a 4 channel transmitter. do you know how to hook up the veetails? sence you dont have mixers with the cheaper radio you can do a mix on the veetails to bring down the atvs some as 30% travel is by far too much. how big are you making this? i would advise you to figure out a target weight first. if you are going to go smaller the draganflyer blades will do great but you have to gear them down to about 1000 rpm or less before you have to reinforce them a bit with carbon fiber laminate or something. if you plan on going over a pound, go with the smaller blades. i know it doesn't seem logical as it will make your rotor disk loading higher and make it less controllable but those draganflyer props can not handle the rpms needed to generate enough lift to power a model much heavier than 1 lb with their construction and specifications. once you add up the weight of all the components (allow about a half ounce at least per speed controller if you are going real cheapo) find a motor gearbox match that will suit your needs. www.balsapr.com has a good list of motors and they all have statistics for props and voltages so it will really help. it tells you thrust, current draw ad different voltages with diferrent props. those stats are only accurate for the props they sell and the other blades (the todds models ones not the draganflyer ones) are almost identical so it is a good source. i am using the EPS-300C-C system they sell. it is a 5.33:1 ratio and is swinging a 10x4.5 prop drawing about 8 [email protected] volts. for the four motors, that's about 32 amps so you have to find a battery that will put out that kind of current that doesn't weight too much. if you go to batteriesamerica.com and click on battery cells, the one that works best for this application (around that same draw and weight limitations) are the cp-1300 scr cells. you you won't find a commercial battery pack that will work very well. those cells i mentioned are ultra low impedance meaning they can put out a lot of current for their capacity. they are micads listed under the fast charge cells catagory. they are only a 1.3 ah battery however (you sacrifice capacity for the low impedance) and at that amp draw you only get about 2 mins of flight time. that alone is a $40 pack (for an 8.4 volt pack) and if you go smaller you will most likely fry the batteries awful quick. you can go with lipolys but you have to get a lot of huge packs and then you get a lot of flight time but you will have to get so many it will cost you at least a hundred dollars for all the cells. i am not dictating i am just saying that unless you want to spend a bunch of money you won't get a lot, and in my opinion these are your best bet. once you figure out all that then you need to figure out what speed controllers you need. don't go too heavy, and if you go too cheap they may not have a good enough resolution to allow for an accurate control. remember these are designed to power a single motor on a plane so accuracy isn't an issue. so when you put the cheap stuff in a thing like this it really shows. if you can find some of hitecs now discontinued sp-1010 speed controls, they are 10 amp rated, very very fine control, they have both motor arming switches and bec switches. but nomatter what you do, put a fuse on them. there's a lot to this.

littlefreak

I was considering buying the draganflyer frame too. So it will almost be just like the real draganflyer. Only differnce will be the electronics. Also i was thinking about if i can make it run for any longer then 15mins. Be kickass to get one to run with solor power..(i wish) how much batterylife you think i can go with out makin it to heavy.

Spaceclam

i really can't say. it depends on how much money you want to spend, the other electronics you use, motors, props, everything. however if you buy the draganflyer frame that's half the accomplishment gone. you can't really brag about it being homebuilt that way. the frame is $75 i think and you did say you wanted cheap. i know the guy who designed the electronics for the draganflyer. one of the first things he said to me was he did custom electronics becuase he did not think it could be done with off the wall products due to accuracy issues. so you really need to focus your money on the electronics as i found out. you can still buy it, i am not saying you can't. but it seems to me that you are going against your focus on cheap. on that note however, if you are going to get the draganflyer frame or make one that is about hte same weight, go with the draganflyer props and use motors geared like 15:1 or so to bring it down to speed. if you do that you can use a smaller motor and hence use a lot less energy and allow you to use a cheaper, lighter battery and more flight time. however i had already shot for my desired weight becuae i wanted it to be more resilient to wind and it has about 6x the payload capacity of the draganflyer, but at the sacrifice of flight time. if i want4ed it lighter i could have used smaller motors, geared them down a lot more so they can still spin the prop and put on a lighter battery. the draganflyer can not really be flown in the wind. you make a sacrifice. responsiveness for durability in flight. you siad you would probably be flying it indoors so you could probably go light without a problem. one other thing though. gyros. i discovered that mine was almost unflyable without them. if you are flying indoors it is even moer important because you don't want to hit furnature and wreck the model you worked so hard on. it is important because a slight radio glitch or whatnot will affect one or more of the motors as they would servos and it can send it off in one direction or another. gws makes some that sell for $60 apice. they are really light (7 grams) but the centerpoint has to be adjusted every time you turn it on. they are non remote ajustable, (which doesn't matter if you are getting a non computer radio) and will work jsut great for your application. out of curiosity, why do you need a radio? is this your first model? this would really make a poor first model to learn to fly. if you already have a radio all you have to do is make this one the same channel as the one you already have and you will be fine. if this is your first model, however, i would spend some time on a simulator (realflight or something of the like) and fly some helis before you even try this. i have been flying for about 4 years now and it was tough for me. these models are inherently hard to fly, so to make it stable be sure to put the battery way down low and the props way up

littlefreak

Well I fly real planes. And I have flown RCs many times b4 at the airport I fly real planes at. But never owned one of my own. So yes this be my first build but I have had practice flying RCs. I also being board and doodleing in class Came up with idea that stick the the hole ufo idea of the dragan fly makes it realy light with cheap and safe frame. A foam disk.. Carve whole for the props run wires throuhg with like a stick or some kind of needle and thread. This would be perfect for me cuz the props wont be open on the sides so if it runs into something all i have to worry about is a dent on the side. And I was already look at gyros.. Will i need 2 or 3 gyros?

Spaceclam

my original idea for building this was for it to be a ufo as well but i did not know where to get cheap foam cutting like that or anything useful. you will only need 2 gyros if you go with the veetails. jsut plug them in between the aileron and elevator channels and the vtail mixers so it affects both motors.

secretspy

hmm, thought I posted my message...guess I lost it or did something wrong...let's hope this one works.

A few questions:
1.) How are you guys keeping the prop from coming off the shaft with the motor reversed? 3mm Nylock nut?
2.) Is it really that difficult to fly without the gyros for aileron/elevator? I fly a conventional heli and the only gyro is for the tail rotor. I was planning on doing the same thing. (my rudder will be controlled via tilt rotor....motors attached to servos...has anyone done this?)
3.) What kind of motors does the real dragan flyer use?
4.) What is the power/weight ratio of the real dragan flyer? (I'm an Aero engineering student @ purdue, I'm designing my own :-D )
5.) Is there a site with all this technical info about the dragan flyer?

thanks

Spaceclam

the prop fits over a nut so i use the 3mm locknut in there. on the top and the bottom, i use a regular 3mm nut and tighten it against the prop. kinda like putting a tripple lock nut assembly on a four stroke. as the tightening nuts the nylock oneswon't do much good. i used the nylock on the propeller becuase it has more side area and the prop fits over better. it is tough to fly a draganfly oriented craft without gyros. becuase of the design, it is far more sensitive to radio glitches, wind etc and the gyros help correct it. the real draganflyer has gyros too. as far as the rudder goes, you can use tilt rotor, but it is probably going to cost more to have the gimbals manufactured than to buy the veetails. (the vtail method electronically mixes the motors so that one rotating pair speeds up and the other pair that counterrotates the other slows down causing torque to turn the model) it is much lighter and has no mechanical possibility of failing in flight. however, the gimbals would prevent it from becoming unstable when too much rudder is applied. that shouldn't be much of a problem however as the rudder in this type of thing is more of a correction than anything. either way is good. i just prefer the electronic way because it can't fail in flight or be affected by vibration and it weighs only about 1.5 oz for all three mixers. the real draganflyer uses highly geared 280s i think. you might want to go to www.spectrolutions.com and email mike. i think he was the electrical engineer. the props spin no more than 1000 rpm, so they are very undercambered and flimsy and the pitch on the props is also inconsistant from blade to blade so higher rpms won't work very well at all. if you plan to gear it down to those rpms, do note you aren't going to get much thrust. the real draganflyer weighs about 1 lb (half as much as mine but mine is bigger) so the thrust-weight ratio is probably anywherre between 1.5:1 and 2:1. i understand it doesn't have too much power. however, because of the steeply undercambered blades pitch and roll response is more sluggish but more effective (because of the lighter rotor disk loading) than my design. as far as technical specs you could again ask mike. if he does not know he probably knows someone who does. his website is very out of date but you can also get some draganflyer parts there. it has been so long that they may have stopped carrying it. also, www.draganfly.com might have technical specs or contact info for you. oh one more thing about the gimbals. in a model airplane news magazine, i noticed an article about a guy who did it wiht 2 props instead of four and used gimbals to do it. you can look over his stuff at www.gressaero.com and look around. you can contact the guy, he is very nice. you might be able to ask him about the gimbals. gimbals or electronic method is really a matter of preferance and what is most available to you.
cheers

secretspy

Thanks for the info. I just have 1 more unanswered question. How do you connect the 3 gyros? The way I'm thinking, you would need one for each motor, plus one for rudder = 5 gyros, because they all send out their own signal. I'm also doing the mixing on my *brand new* JR XP8103 birthday present, which has the 6 mixes I need (say for example that the front motor is on the ele channel, left motor is on the ail channel, and the rear motor is on 5, and the right motor is on channel 6):
mix1: +ele to -ch5
mix2: +ail to -ch6
mix3: +throttle to +ele
mix4: +throttle to +ail
mix5: +throttle to +ch5
mix6: +throttle to +ch6

then rudder is split to 4 servos for tilt-rotor, which would not require a mix.

How would I connect 3 gyros to this setup? I could easily do 5 but thats way too much money and weight. Have you flown conventional heli's? If so, is this anything like that? I'm assuming that if I can fly a regular heli that I can fly this (or pretty much anything, maybe thats being too cocky...) I think that if I get it tuned just right I won't have a problem.

So you never have a problem with the prop coming off with your setup? If I read your post correctly, the assembly sequence is: 3mm nut, locknut, prop, 3mm nut....correct?

I am also shooting for under 1 lb....lets see if that actually happens!

Spaceclam

if you want to use only 3 gyros, you will have to use onboard mixing, here's why. a vtail mixer splits the signal into two other signals. the master + the input of the slave, and the master - the imput from the slave. if you want an aileron gyro to affect both motors, you have to put it in-between the receiver and the aileron (for example) input of the mixer. if you are shooting for under 1 lb, you may not be able to do it with off the shelf electronics. you may have to design and build your own circuitboard to eliminate all the weight of wires and packaging etc. also, if you are shooting for under 1 lb i would use the model's torque to control rudder instead of tilt the rotors as that will weigh considerably more especially including the gyros. if you use onboard the setup will be much simpler and cheaper as you will most likely have to custom manufacture the gimbals yourself. i would use the 6 mixes to reduce the throw (the minimum of 30% on most radios is way too much) and to be able to raise the rates on the flip of a preferably spring loaded switch in case of an emergency. to reduce the throw i have a set of mixers mixing both the aileron and elevator channels to themselves with a value of -70% both ways giving me (along with the already decreased rates) about 9% travel and it will take 2 mixers for that. whel i flip up the switch those turn off and another set turns on that mixes them onto themself at a rate of -60% to give me a bit more travel in case of gusty winds or something happens to one of the motors. that will take another 4 mixers. if you want to put a gyro on the urdder, make sure it is heading hold and that you can decrease the control gain to almost nothing. when you have too much, it will over correct. while the yaw will not actually respond to the rudder imputs frantically overcorrecting becuase it is a kind of gradual thing, the model will become unstable along the axis on which the thrust has been brought down to change the torque. if you go tilt rotor you may have the same problem except it will probably respond more and quicker, but then again you might not have that problem at all. i personally do not use a rudder gyro because the only one i have (i can not afford another) has a minimum of too much control gain. while it will still fly, it isn't as fun and when the model sudeenly turns from a gust of romething it it really tough to recover. i am sorry, i messed up in my earlier post about how i fasten the props. on first (the bottom) goes a single 3mm nut, you can use either normal ones or locknuts it really won't make a difference. then i slip the prop over a nylock and bring it down the shaft. i then put two normal nuts on the shaft (they use less space) and tighten them against eachother at the very top of the shaft. once i have don e that, i will tighten the prop against the top nut so the bottom one doesn't break loose. then i take the first nut i put on, the one that can be either nylock or regular, and fasten it holding it and the top one and tightening them against eachother and the prop is very secure. it still doesn't hurt to check it every now and then (best before every flight) becasue sometimes if you hit the prop the nut will break loose and endanger your model. just becasue you can fly a heli doesn't mean you can fly this model. i have flown conventional helis (rc) although i do not own one myself. they fly very very differently, but it may be easier.