4 EDF VTOL idea

[canadian_bacon]

Here is a link to my thread that i started in the edf jets forum, and probably belongs in this one.
Any comments or ideas that you have to add would be appreciated, thanks.

http://www.rcgroups.com/forums/showthread.php?t=473262&highlight=edf+vtol

[v22chap]

looks like another design coming to life ,,looks good . This new thread is really going great ,,lot better than I thought it might .There are more guys out there working on VTOL's than a person would think. ;) :D


I agree that the fans are going to be marginal ... you may have to go with bigger ducts with cut airplane props. Tom Hunt has done a lot of NASA research on this and a larger duct with a slightly shortened 9X6 airplane prop makes more thrust than a regular 4.5 " ducted fan !!!
Here is a pix of a guy that did it this way with IC engines.
http://static.rcgroups.com/gallery/data/500/14579whitewithwing-med.jpg
As I remember he said that he got it to hover but hadn't tried transition yet.
Good luck and keep us posted
Larry

[canadian_bacon]

That is a pretty cool lookin setup.

I would like to keep mine small enough for indoor flight, preferable less than 20 - 25 inch diamiter. Making my own ducts and props may be what I end up doing. I think I will try and find some smaller props, possibly counter rotating, and try testing them out.
Has anyone else made their own ducted fans, or similar setups?

[canadian_bacon]

I have come up with an idea for a test frame for 4 edf vtol models. It will hopefully allow me to figure out the best configuration of motor placement, the angle that they sit at, the angle that they rotate at, and center of gravity. Hopefully anyways. I think it will be a pretty good platform to test out my ideas on. I will probably have a working model of it done in the next week or two. Having all of the electronics, however, may take longer.

I have attached my design that I will be following.

Any input you can offer would be great.

[StormySkies]

That looks suspiciously like Rhino.

[v22chap]

looks good ,,the only thing I can see that might cause problems ,,is the rotating arm mount to the fuse .. the one point probably will cause it to bind up and not rotate easy might want to extend the fuse mounting out a little to give it another bearing surface.
Larry

[canadian_bacon]

That looks suspiciously like Rhino.



How did you guess? It is an awsome 3d tool. I tried a few others, and they were pretty weak in comparison. It only took me like 30 minutes to make up those pics.

[canadian_bacon]

I agree. I am gonna make some longer mounts, and probably use four servos not two. I am gonna try and mount the servos on to each arm mount, and not the main body. This way I will not have to worry about pushrods when I move the mounts around testing different configurations.

I don't think I will be able to do the one setup, due to that the servos I have are poor quality, and not good enough to do direct turn on the main arms. The other setup should work better.

[v22chap]

Ah ,,that looks better :D and good idea about putting the servo on the arm so you can move them around.
Larry

[canadian_bacon]

I am going to try and make my own ducted fans using some helicopter parts. I plan to go pick up some tail mounts, motors, and props from indoor helis. As well as some castle creations pixie 7 esc's and parts to make my test frame. I will then use either my 2s 1320 lipo or 2s2000 lipo batteries. And then I will pray that it will eventualy fly.

[v22chap]

then I will pray that it will eventualy fly
you never know until you try ,,all the figures in the world don't always make it so on these VTOL's :eek: ;) :D
Larry

[canadian_bacon]

Ok, well I dont think that using tail props is going to work to well, as far as efficiency to thrust is concerned. I am going to use 4 GWS EDF 40. They should do the trick, with 87 grams of thrust per motor at 8.4 volts, and 70 grams at 7.2 volts. Assuming the thrust in grams listed on the gws box is static, I will be able to lift a total of 280-348g at full throttle. I would like to be able to keep my vtol as efficient as possible, so I will aim to have a total of 100-120g for my finished model. Right now it is looking like it will be a little more, but i think it should be okay as long as I can keep a 2.5:1 thrust to weight ratio.

[canadian_bacon]

ok, maybe this wont work as well as I thought. My weight without my edf's will be around 100g and the edf's are 27g each. Which leaves me 80-140g thrust after the 200g frame which will give me a minimum of 1.4:1 thrust to wieght ratio. Not quite what I was looking for, but oh well. I dont think that I will be able to much better.

I am goin to try and reduce weight for flight for now untill I can think of a lighter setup. I am going to make the arms be able to turn, but also be locked in place to see where they need to be centered.

[v22chap]

welcome to the world of VTOL ,, weight ,,,weight ,,,weight.. always watching the weight.did you put the tail rotors in a duct or just in the open??? Tom Hunt did some research for NASA early on and found that a cut down airplane prop in a duct had more thrust than the early on ducted fan units ... I will try to find that article again and post it for you .
Larry

[Tuner]

I have always been curious about making a Duckless Ducted Propeller.

Basicle Imagine a thin 1-11/2" tall carbon fiber ring surounding the propeller attached to the tips of the propeller Much like these toy helicopters only it is designed to act like a winglet/ducting.

I like this because then I can get the static thrust from a large propeller but have a little more safety of a ducted prop with out all the added weight.
Only issue is this probably will double the inertia of the propeller and I worry it may make things more ineffiecent.

Not to mention it could be difficult to balance.
Someday I will experiment as connecting the duct to the fan or prop seem very interesting to me.

From Watching Mythbuster try to build a twin Ducted fan backpack type system it is very hard to get static thrust from a ducted fan.

[canadian_bacon]

I was looking at my mini dragonfly, and if I disconect the main motor, that little tail has quite a bit of thrust. I am going to get one edf, and compare it to a home built ducted prop, made from a indoor helis tail setup inside of a cardboard tube from packing tape.

[v22chap]

sorry guys ,,I was suppose to find that article by Tom Hunt on prop fan vs ducted fan wasn't I :o :rolleyes:
well here it is :The inlet lip makes a lot of difference if I remember reading right ,,it has to rounded over not just blunt Some where in my unpacked stuff ,,from 6 yrs ago move ,,I have the plans for the vertigo's prop fan and I think that is where I read about the inlet lip .If you need the plans I could be pushed to go digging ,,I guess. :rolleyes: :p

The control vanes that he uses on this vertigo ,,work pretty good and would probably work for both your applications... will try to post pix of that too.They also have to be exactly 3.5 inches away from the fan ,,,if I remember right to work at full efficiency.


http://static.rcgroups.com/gallery/data/500/14579propvsductedfan1-med.jpg
http://static.rcgroups.com/gallery/data/500/14579propvsductedfan2-med.jpg
Good luck and hope this helps some
Larry

[canadian_bacon]

Well, I tested an EDF 40 on a 2cell 1320MAh lithium pack, and it got quite a bit of lift. I am not realy setup to measure just how much it was lifting, but I think that four of them will give me more than enough power.

I have had another design change, I am now going to mount each of my fans directly onto a servo. This is going to cut down the weight of the frame, and keep the fans closer together.

If you cant tell by now, I am new to the hobby, and not very skilled at putting things together, so the less actual building I have to do the better. I have decided that my original test frame is going to be to hard to put together, so I am figuring out ways to simplify the design.

[Tuner]

I have some experience with this.

Its not a good Idea.

That said it sure is easier that way.

Basicly the weight you save is not worth the battery power lost by a servo constantly or the slopp.

Servos have slopp in them wich will allow your powerplants to woble around. While not entirely bad its not good.

Also you servo will constantly be ON trying to keep your powerplant in its position. This will suck your batteries down fast.

What you want to do is modify a servo so that it runs continuosly thier are a lot of website out their that will explain this.

Then create a way to insert a long Bolt into the main servo shaft. If the gears are plastic it is easy to drill a bigger whole and insert a bolt. Glue the bolt so that it does not move.

Have your Powerplant attached to a shaft that attaches to the body with bearings to support it so it rotates freely. Connect a control arm to the shaft and get yourself a Nut for the bolt attached to the servo and attach the nut to the control arm. When the servo turns it will act like a screw drive garage door opener. Whats nice is all the force from the powerplant that normally would be trasfered into rotating the servo would now be tansfered into pushing and pulling the bolt essetialy locking everything in place.

Now all you need is to rig 2 small toggle or button switches to flip when the powerplant is rotated to the proper positions. You may need a resistor on each switch.

If you want proportion positioning then you will have to attach a potentiometer to the powerplants shaft and wire it into the servo. Now its starting to be lighter to mount directly to the servo. So if you want to not just have the powerplant in 2 positions but rather rotate it to any position, directly attaching it to the servo is simpler but, with the problems mentioned above.


I am considering designing a servo for this exact use. Actually I am considering designing a Servo Gearbox for a popular brand of servo so one can just remove the standard gear box and replace it. One version has a rotating shaft the other version has a linear output.

[Tuner]

V22 Thanks a Wounderful post.
If you could ever scan the plans for the inlet I would love to see it??

Scott

[v22chap]

Scott is right about the servo deal .As a proof of concept deal ,,I would just mount the fans solid and use control vanes on the bottom of the fans to do the controlling .I think that the fan moving to do the controlling is going to be to slow and hard to control.

I will try to find the nacelle plans and scan them for ya Scott.

Scott let us know if and when you get a servo gear box upgrade deal ,,that would really help these light park VTOL's and I think this is where the VTOL is going to come to live first ... what I am doing is to big,to expensive ,to complicated for the first movement of VTOL in to production ,,but these little light ones will sell like hot cakes as it is new easy and different and everyone will have to try one. :D
Larry

[canadian_bacon]

What I am aiming for is something that will take off verticaly on 4 fans, then tilt the fans to horizontal for forward flight. I would like to be able to turn the motors while in a hover to control yaw. When in forward flight, the fans would act as ailrons and elevator.

I don't think that the servos will draw to much power mounted directly to my edf's, but they will not have a whole lot of control while in a hover. I think that the use of gyros will give me the controll the thing needs.

[v22chap]

I know you want to tilt them ,,but just for the hover proof of concept ,,you could mount them solid.
The other thing is the fact you won't get enough rotation out of a standard servo to do 90 deg tilt.You will have to modify the servo's and put in a remote pot like Scott said.

[Tuner]

The $130 Hitec 5995TG robot servo has 180 degrees of rotation. I think it is the only one I know of other than their newest robot servo but it wont work with radio recievers.

Its a bad ass servo I use it running at 7.2v it super powerfull and fast at this voltage. To fast for me at times.

Honestly with a properly modified servo you could get this job done with a small lightweight inexpensive servo.

I can tell you from experince that it will suck your batteries down but if its the price you want to pay for simplicity go for it!
I basicly sandwitch a aluminum servo arm inbetween 3 layers of carbon fiber strips that were .2" thick and .7" wide. I cut out a silouette, with my dremel, of the servo arm in the center strip and cut a whole in the other two one small one for the scew and on large one for the bottom part of the arm that connects to the servo. Then I wrapped the three strips in 3/4ounce fiberglass fabric and smothered it in epoxy. WORKS LIKE A CHARM for building up a servo arm its just hard to make sure everything is straight and true.

Experience VS theory are two different things that is why I built my first model with out the intention for it to fly and sure enough it taught me a lot about some of the difficulties with this type of VTOL that you are considering.
It will be difficult to rotate the Powerplant with the speed you need. That said the 5995TG can do it no problem. That Said Consider using a control surface to vector your thrust. Me I hate that as it is not ellegant but it is very functional and I may end up even giving in to using a control suface to vector thrust it will help when trying to fight cross winds, think about how your VTOL will handle a cross wind will it rotate into the wind to stabilize its self or will it sideslip or just be blown around?

Check out my project its not as well developed as others on this list but it is very ambitous much like your idea. I think you are on the right path and I did consider a Ducted Fan but as of now Im going for High efficency high payload capability so I need every ounce of static thrust I can muster.
http://www.rcgroups.com/forums/showthread.php?t=436841&page=1

[v22chap]

Scott
Thanks for the info on the Hitec 5995TG robot servo I didn't know there was such an animal out there. It will be usefull in the future. :D

[canadian_bacon]

Good point, but I think that I should be able to get away with only tilting the motors 90 degrees for now. I will have the thing hover with the nose tilted up 10 to 20 degrees, do that when in forwrd flight mode, and all of the servos are level with the frame, and I can still have 10-20 degrees of turn left in the servos. To control turn, I will turn the fans on one side more than the other. It won't be very stable, but it should work as a testing platform.

I will have to do some rethinking on my wiring right now. I cant think of how I will get it to work. My first problem is going to be getting all the fans to work together, then it will be getting all the servos to work together.

I think that I should be able to control while in hover mode by using two vtail mixers between the right and the left edf's. Then using vtail mixing on my transmitter. I will then hook the mixers up to my throttle, ailrons and elevator. I will then use one mixer between the left and right servos, and hook that mixer up to rudder, and a 5th channel. I should be able to mixing in my transmitter to do the rest.

[canadian_bacon]

Hello again,

I went and picked up one edf40 and put another 3 on order, along with all the other parts I will need, so I should be able to flight test in about 2 weeks.
I did some testing on the edf that I picked up, and it will take off verticaly up to about 35 grams plus the weight of the fan. so all parts other than the fans can weight up to 140 grams and it will fly. I am predicting my total weight to be about 115 grams, so it should be capable of lifting off the ground.

here is a list of all the parts that I will be using
4 - gws edf-40's
4 - castle creations pixie 7 esc's
3 - v-tail mixers
3 - piezo rate gyros
4 - light weight servos
and either a 2 cell 910mAh or 1320mAh, the difference is 12g, but I already have the 1320

my total wieght should be 108-120 grams, depending on how many wires I can shorten to save on weight.

[v22chap]

Sounds pretty good ,,if you can keep the weigh down like you hope ,,but that is usually not the case as we all tend to build to crash ,,,as my engineer son puts it. ;) :rolleyes: :D

[Tuner]

Yah the 59995TG is quite amazing little servo. I currently run it with a single cell LIPO or 5cell NIMH. AT 7.4v it is down right intimidating literaly this little guy could tear you a new one yet I have still managed to max out its capabilities granted thats with a 10 inch servo arm :)
It works very well with the 14MZ's reciever.

My personal recomendation is to go with a better fan motor combo. V22Chap is right I calculated my total weight then added 20% and still exceeded it.
I could have kept it lighter but I wanted it to last more than one flight test.

The key to Fun light VTOL is SIMPLICITY. If you are making something scale boy you are in for it as you pay dearly in weight to make something look good.

I am currently working on an airframe design the barrows from my extensive Stunt Kite experience and I hope to make it amazingly flexible, yet rigged where needed and light weight airframe using Carbon Sticks and Tubes along with very tightly stretched Icarex or Ripstop Polyester fabric or even thin Kevlar Fabric(sans resin). I herd Koverall & Ducolam are also good. The key is to tensioning the fabric and making sure it is glued to the parts of the airfram that it touches. In an impact the frame can flex considerable but will flex back into its shape with minimal permanant damage.(In theory)

I have kites that can smack the ground at 80mph and show no more than a skuff or minor tear in the fabric. (Granted they have a much higher strength to mass ration)

Some more food for thought.

Good Luck!

[canadian_bacon]

hello again.

Well I think it may be a while before I can get this thing to transition into forward flight for a while. I just tried hooking a servo directly up to my edf and well the best I can hope for is an unstable hover. First off, the servo is to jumpy, may be due to low quality servo, and the other problem is going to be the torque when the motor turns. It is going to make the whole thing twist, unless all the motors turn together, or at least two that will cancell eachother out.

And Tuner, I guess you can say that you told me so, but I wanted to see for myself. I am not going to be able to turn the servos far enough without making the controls very sensitive and the whole thing very hard to controll. But that does not mean that I am going to abandon my idea, I am just going to have to figure something else out.

What I might do is have the servos controll both the elevator and rudder, and do some programming in my transmitter to make it all work out. Then use ailerons to speed up or slow down the motors.

[Lewist]

the gyroscopic affects of the fans rotating is fairly large,

you could fit control vains under the servos for hover control and then link all the fans to a single servo for transition.

[rdresch]

However you do this, remember that when your ducts turn to horizontal roll control becomes yaw and yaw controll becomes roll. Very difficult to do in transmitter.
Rudy

[v22chap]

Here again the Th-2 GP that Joe makes will probably take care of this :D

[Lewist]

IN my Vtol i used/will use conventional control surfaces for flight which opperate all the time, so as speed is picked up the normal control surfaces start to take affect and when full transition is achieved all the gyros and mixers get shut down and throttle control is pipped directly to the motors.

The way i have my controlls setup also means that there is no difference in controlls between hover and normal FFF

I personally felt this was the best compromise. I had considered using the movement of the fans to control ailerons and elevator in normal flight, but i feared the the gyroscopit affects of the motors and fans would mean slow and sluggish controls unless large servos are used (weight!). I felt this was the best compromise between the two!

[canadian_bacon]

I think that I am going to be able to just use my controls to do all the mixing for now. I can run the rudder and elevator to my servos to turn the motors, but I might also have to have elevator control the speed of the front and reaer fans as well, but I am not sure. then I have a switch on my transmitter that will mix one channel into the other, and I will use this to mix my ailerons into my rudder to provide roll in fff, and go without rudder. I think that this will work for now. This way I should be able to slowly work a few bugs out of it.

[canadian_bacon]

I am not to sure of wether or not I will be able to use controll surfaces. I will find out if I can add any kind of body to the thing and still have a vertical takeoff. I would like the thing to stay very small if possible, so what I may end up doing is making some control viens that tilt with the motors. I should be able to realy get things figured out by the end of this week, all of my motors should be in by thursday. I think I have the motor mounts figured out, as well as a frame to mount them on, so that pretty much all that is left is hooking up and getting the electronics to work. Then a complete redesign from the ground up to make it fly.

[canadian_bacon]

I got another idea today for mounting my edf's directly to servos. What if I were to take the potentomiter out of the servos, center it, and use gyros to keep the servos centered. Would this work? Or would I still have to use the pot to make shure that the servo's do not keep turning. I may need to get some better pots, that will set a deffinate center and keep the servo from continuously turning. Or just better servos than the crappy P&C 9 gram ones that I have now. I think that they are nock off's of a nock off.

[v22chap]

I don't think this idea will work ... you need the pots to make the servos work...the gyro's straight to the servo will not work.Now if you mechanically tie the pots back to the servo arm then you could slow the response time down some by going long on the pot arm and short on the servo ,,but I think you could do the same thing pretty much by just turning down your ATV on the ail and elev of your tx some.

[canadian_bacon]

Well I have got most of my parts and will try putting it together at work tomorrow. The only thing is that I will be testing with only one gyro, I will get the other two after I find out wether or not it will fly.

The setup that I settled on is going to be just vtol and no fff for now, i will work on that later. I am going to ailerons and elevator to two mixers to mix with throttle, these will then conect to kitty corner motors. I will turn my transmitter to delta wing mixing to mix the ailerons and elevators together, so I can arange the motors with two in front and two in rear. I will then split my rudder signal wire to the four servos attached to the motors. And then test some different batteries. I will try some li-poly 2cell 910 , 1320 and 2000, as well as a 3 cell 780 and 910. I will run my battery through a watt meter to find the most efficient battery for thrust and power consumption. I am not too sure if the 3 cells will work at 11.1 volts, the motors are rated for 6-8.4 volts, so I will probably end up with the lightest 2 cell that I can use without drawing too much current from it.

[canadian_bacon]

I put all the components together, and after a few hours of two motors not arming, I figured out how to plug everything so that it would work, then another few hours trying to figure out how to set my transmitter. In the end, i got a 10 - 15 second stable hover about 2 feet off the ground before the batteries lost power and it came down. I think that it needs a 3 cell not a 2 cell which I was using.

I am going to have to find a better way to mount my fans to my servos, right now they are all at different angles, which is not going to make for easy flight. I plan to make another frame using some 1/16 carbon fibre sheet, which I hope, will be stronger and lighter. Right now I have a 2"x5" piece of balsa with all of my electronics and and motors mounted to it, and a block of foam beneath it to hold my battery, and 4 training legs to keeep it from tipping.

[canadian_bacon]

I have rethought my approach for now. I now only have only one servo, it is directly attached to one edf 40 for yaw control. I then mounted the other 3 edf 40s directly onto the frame so that they do not move. I put the rear three at about the same distance appart, then the front is about an extra 2" out, so I could have room for battery and electronics. I got about 3-4 minutes of actual fly time of 2-3 feet off of the ground, before my front esc decided to quit, and it did a nose stand. This was with a 2 cell 1320mAh lipoly pack attached to the frame.

I think this is pretty good considering this is only the second prototype that I put together. If I can make this work, it will only be a matter of time now before something like this will be available as a rtf kit.

[v22chap]

Hey this is great to hear . hope you get an esc that will hold up
Now are you using vanes to control the other axis ?

[canadian_bacon]

No i am not using any control vanes, just a differential in power between the motors. I thought they they would turn out to be too heavy to use vanes as a control system. Having the tail edf to steer, and the other 3 at a slight angle is the simplest way in my mind, and it seems to work alright.

I have ordered 4 GWS edf-50ah with 3 blades. The specs on them show that they will handle a 3 cell lipoly pack, and only draw 2-3 amps for each motor, and have more thrust than what I have now for pretty much no additional weight. I am going to get a 3 cell 910mah pack to power this thing, and hope that this takes care of the front esc reseting during flight.

[Lewist]

so what gyros are you using with this?

[canadian_bacon]

Sorry,

I lied, I only got about 1 1/2 minutes of flight before electronics didnt have enough power. I wasn't timing my last few flights.

I am just using three gws pg-03 rate gyros with all of the gains turned about a 1/4 of the way from the lowest point on the dial. They seem to work, but it does tend to drift a little bit, but nothing past what I can correct with controls. The only problem that I have right now is that when power gets low, the esc's start to turn off. I hope to fix this by upgrading to 4 edf-50ah fans with three blades, then to use a 3 cell 910 lithium pack. I think that the higher voltag will fix the electronics problem, and that the 50's will be a little more efficent.

[Lewist]

just turn the esc cutoff off.

this is what i did, I figured that by the time the voltage got to the critcal level there would not be enough power to hover properly anyway, and the last thing that you want is the low voltage cutoff killing one motor and the whole lot crashing into the ground!

[rdresch]

Thats typical with many esc's. Some allow you to set the cutoff voltage. When the esc's cutoff, how low has the battery voltage dropped? If possible lower the cutoff voltage, but quit flying when performance drops. Better to kill just the battery than the whole rigg with a crash, which will probably kill the battery anyway.
Rudy

[canadian_bacon]

well I tried turning the cutoff off, and used the battery with low charge, and it seems like the gyros are flippin out. The yaw gyro which turns a servo, is making the servo go nuts.

I need to come up with a new way to mount my EDF's that is light and strong. right now I am using some servo arms bolted to the edf, and glued on to an aluminum tube. but the servo arms keep breaking, no matter how much CA is on them. Does anybody got any ideas that you have used or can think of. I am running out of ideas for mounting them. The only other idea I have involves drilling a hole through the the cowling and sticking a dowel of some sort through it and ataching it to the heatsink.

[v22chap]

I have not mounted many electric ducted fans ... but how about threading a bolt thru the alum tube and then rubber bands around the fan and bolt ,,kind of like they do on airplane props for electrics ??? Light ,simple ,flexable ,adjustable by adding more or less rubber bands.
????????

[Tuner]

Are you mounting it right next to the fan in the duct.

If not, then simply get a screw and screw the servo arm to the duct. O use a nut and bolt??? I use servo horns for this all the time when I want to quickly create something to hold a Rod/Tube. I like the 4 point arms or the circular because I can bolt them in 4 places circular for simple uniform or flat surfaces 4 point for complex curved surfaces.

Glue will never work for this unless you use some fiberglass cloth to reinforce.

I like the rubber band idea you got to do it corrctly though otherwise it will be loose.

If your really stuck show me a picture of the inside of the duct I can help.

[Lewist]

I would think that the nut and bolt idea would be the best. use some small round head bolts and there will be minimal disruption to the airflow!

Or use balsa to make some ribs round the outside of the fan and then attach to those some how!

[canadian_bacon]

Ok i tracked down my little brothers toy camera and managed to get some pictures, but they are kinda low quality.

[canadian_bacon]

my next step now that I know it will hover is to go back to my original idea and make something that will transition. I plan for it to have a 20 inch wingspan, and be pretty much just a flying wing. I will post again when I start construction.

[Spike_Spiegel]

I hope this doesn't sound like a dumb question ... I know sometimes people just want to try things for themselves ... but are you aware of these products?

http://www.searchlight1.com/Movies/draganfly.jpg

The Draganfly is expensive (starts at $750) but is the most sophisticated, supposedly capable of a near-autonomous hover. (I've never seen one in-person.)

http://www.searchlight1.com/Movies/ufs.jpg

The "Ultimate Flying Saucer" is an older (circa 1999) that was tethered, but flew an incredibly level, stable path. I had one for a while ... it suffered from a terrible battery and used old mechanical gyros.

http://www.searchlight1.com/Movies/xufo.jpg

The X-UFO seems to be the next-gen version of the UFS, but is now un-thethered and seems to be equipped with more up-to-date tech. They run about $200. I have seen a video clip of it here: Silverlit X-UFO (http://www.break.com/index/xufo.html)

All of the above (and also the Vectron Blackhawk) seem similar to what you are trying to accomplish. I thought if you weren't aware of these gadgets, seeing them might help you with your process or give you some ideas ... if you have plenty of cash, you might even buy one or two to reverse engineer a few of the components.

By the way, I plan to follow your progress ... looks fun!

- Spike

[canadian_bacon]

I actually work at Draganfly, so I get to see how all of our helicopters work, and the Draganflyer was actually the starting point for my project. I wanted to make an edf version of it, and I still might. I looked up other ducted fan projects, and decided to make something like a flyin car, and now I want to make it into a ducted jet that will fully transition from hover to forward flight.

[canadian_bacon]

I think that I have come up with an airframe that will convert to fff. I plan to use some thin depron for the wings and shell, with a simple balsa interior frame to mount the edf's to. What do you guys think of this air frame?

[rdresch]

I like the basic idea, but be sure to keep the intake and exhaust paths clear.
Otherwise you will seriously hurt DF performance.
Rudy

[v22chap]

I agree with Rudy ... great concept ,,keep ducts clear
Larry

[Spike_Spiegel]

Love the airframe! Reminds me of the snowspeeders from TESB!

Make sure it has a deployable tow-cable ...

- Spike

[Spike_Spiegel]

You work for Draganfly, huh?

One slightly OT question ... how close can that thing get to an autonomous hover?

- Spike

[canadian_bacon]

For the Ti-Pro, outdoors it is close with its thermal self leveling, it would need to have a very light autonomous flight system, less than 4 oz or 120g. you might be able to go heavier with a bigger battery, and more powerfull motors. But that will make it less stable, more stress on gears, and will burn out motors faster. With a 4 cell instead of 3 motors burn out at 20-30 minutes.

Thats what it looks like. I thought that my airframe was starting to look familiar.

[Tuner]

I liked you 3 3DF airframe design. The only issue I see is you will have a very tough time transitioning if your ducted fans are not counter rotating.

It is not hard to get a flight computer/INU combo under 2oz.
The paparzzi project is creating a hardware peice that would be what you are looking for. I am buying my INU from Atair Aerospace unless somehting changes my mind as this eems to be the best INU out their.

Scott

[canadian_bacon]

I hear a lot of talk about flight computers in vtols. How important are they. Does transitioning from hover to forward flight cause the thing to become very unstable? is it because when the motors start to tilt, just using a differential of power to the motors to control pitch and roll will not work? My idea is to tilt the motors 20-30 degrees, while gaining altitude and speed until it can finish the transition.

[Tuner]

The problem is you have 4 gyros rotating at high rpm. When you tilt them you you get a rotational force 90 deg in the direction of rotation also known as gyroscopic procession.

If you have counter rotating fan they will eliminate them. In theory you could counteract the forces with differential vectoring of the thrust but this is assuming that you can counteract all of the gryo forces in this manor and that in doing so it wont reduce power going to your forward movement... alll theory and speculation just need to test and crash it in the end.


A flight computer is not needed unless you want autonomous flight.
You can get away with gyros and a mixer or just gyros.

Scott

[v22chap]

What Scott said ,,,and more .If you had to have them then the Bell XV-3 would have not flown thru the conversion into airplane mode as I am sure they didn't have computer controls in 47. I am sure that it takes a load off the pilot and that is what most of the computer talk is about ,,,,and plus you need the mixers and the computer radios to do some of that for you.

The differentail motor still works in the conversion ,,but soon you need to turn off the differentail motor RPM change to get all the forward movement you can get to stay wingborn,,, atleast for us using cyclic and collective pitch. With your fan setup ,,I am not sure as I have never done anything with fans,,I think that the dif motor RPM could still be used for yaw control but Iwould think the differential fan movement you used in hover for the yaw control should be turned off eventually ,,and this is where we are trying to use an onboard chip to change things around and shut things off for us.Your pitch axis control could still do its control I think . What you are doing is a lot different than most of us that are using cyclic controls.

No,, the bird doesn't become unstable in conversion ,,,if you can maintain and increase the speed forward that you need ,,but if you don't then it becomes very unstable ,,just like an aircraft that stalls out ....snap and spiral down . :eek: