HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 23, 2013, 05:49 PM
Will fly for food
ilektron's Avatar
United States, CA, Carlsbad
Joined May 2011
532 Posts
I just used fishing line I had sitting around. I recommend putting the line right through the CG, and give it as much room as possible. Now that I'm waiting for parts for my tiltrotor, I may throw my autopilot back in the cube and spin it up.
ilektron is offline Find More Posts by ilektron
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 05, 2013, 12:33 AM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
Hi again Kelly, thanks for your comments and help.
The first try on this way, using 4 elastic ropes fixed to fuselage to try ascend, at moment to fall down the elastic ropes broke the fragile poles.
For the second try, we moorage a blanked to 2 tables as you can see in the pictures. That went fine until a power excess pull out the dronopter and crash outside of the safety zone jajajaja.

In this experiment we proof the power of the motor and the capacity to rise.
We need a more resistant fuselage and an more aerodinamic design.

IŽm working on Dronopter2 design, and Dronopter3. (pics soon).
This week IŽll send to laser cut the fuselage and other things.
We need to include some improvements.
STARFOXFAM is offline Find More Posts by STARFOXFAM
Last edited by STARFOXFAM; Apr 05, 2013 at 01:03 AM.
Reply With Quote
Old Apr 05, 2013, 10:44 AM
Registered User
Joined May 2010
430 Posts
Hello Victor,

I'm pleased to hear of your progress, and continued development.

I hope you don't mind a few comments on your new version/drawing.

Those upper skirts are going to cause you some trouble possibly, this additional lifting (wing area) ahead of the MAC is going to act to move your cg placement aft-ward during horizontal flight. In a sense it just counter acts the skirt area on the lower sections of your sphere.

I analysed the Japanese sphere design from several perspectives. The spoilers help to dampen low speed hover oscillations, but they also move the cg aft-ward during high-speed horizontal flight, this is sort of an enigma as to whether they degrade horizontal flight. Look at it this way, in hover the spoilers are mostly pulled upward, surfing on the inflow air that move horizontally into the propeller disk area, during a sudden burst of power they all deploy downward, during horizontally flight the selectively deploy downward with regard to the relative wind associated with the angle of attract of the entire device. The downward deployment increases the wing area ahead of the fixed CG/MAC location which should make the craft less stable in high speed flight.

But wait a minute, If you read the patient that was filed by the department of defense in Japan, you'll clearly read that the craft has a claim indicating a moveable (adjustable) CG is employed. This makes sense, and it shows up in the patient drawings too. Now, just because it's in the patient claims it does not prove that Sato used it in his version we see in the videos.

This moveable CG is very important to consider and it has been overlooked, perhaps do to my lack of expressing this fact only once or twice in the Japanese Drone thread.

As a retired educator I have noticed current aviation/aeronautics students want to ignore basic aerodynamic fundamentals, thinking that they can install the latest controller of the day into any shape and expect it to fly correctly. I think it stems from three major factors.

1. A fascination with computer / programing control in every aspect of our lives.

2. A lack of understanding of fundamental aerodynamics. Either the curriculum is inadequate, or student / faculty relationship is failing. I don't know, but something is going very wrong at the upper education levels.

3. Combining the two concerns above and you have in development of the tri-copter / quadcopter etc., which has no real aerodynamic surfaces, thus the need for basic and advanced aerodynamics is not required to design, these devices. A sense of over confidence occurs that carries over into design that do employ lifting surfaces and they they all fail, completely. The student gives up and moves back to the simple quad-copter designs, under-mining their own education.

I make these comments in hopes of reaching all of those great forum readers out there that are drawn to this very complex design, I want them to be successful in their pursuit.

These comments are not directed directly at you Victor but to all persons interested in aviation design. First the basic flight dynamics must be meet, then the avionics developed, not the reverse.

I applaud your fantastic work, so don't take my comments as an insult or attack, just a form of redirection of development thoughts perhaps. In your case I don't see a lack of understanding of flight dynamics, but perhaps you have too many challenges built into one project. Your avionic package is spectacular, just a few changes to the airframe maybe required. Flight testing with simple proportional gyro maybe the best solution until the airframe design is solid.

May I suggest you consider using the design that Sam employed. A resilient flexible cage of carbon flat stock or tubing with foam vanes

For the outer cage use carbon flat stock or tubing joined at the top and bottom by a simple disk. This outer cage will flex and absorb stress and strain forces. Support the inner control system made out of ridge foams stock on rubber supports, perhaps short pieces of surgical tubing. At the terminus of each vane cut a small nub or nipple that the rubber hose slips over, the other end of the rubber hose is pierced with a hole and slides over the carbon cage flat stock or tubing, much like a high performance stunt kite. Using this design the inner rigid structure is isolated from the energy absorbing outer cage. This way you can subject the craft to robust forces without harm.

Best regards,

Kelly
corocopter is offline Find More Posts by corocopter
Reply With Quote
Old Apr 05, 2013, 12:03 PM
Registered User
Joined May 2010
430 Posts
One more idea borrowed from Sam's "Taiwan Drone" design,

Why not build the inner structure also from carbon rods with foam vanes, but support / isolate the inner structure from the outer cage with the surgical tubing, that way it is very strong, light weight, resilient but still ridge enough for precise control.

Make sure the lower vanes plus "body lifting" area are approximately double the area of the upper vanes for testing, reducing this area if required after stable test flight. Remember air velocity is higher on the upper vanes thus they have more power proportionally than the lower vanes, thus the size reduction is required on the upper vanes to balance the forces of the control vanes.

Kelly
corocopter is offline Find More Posts by corocopter
Reply With Quote
Old Apr 05, 2013, 01:01 PM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
Hi Mr. Kelly...
Thanks for your comments and contributions. Your suggestions are perfectly informed, you are very experimented on this area, I see.

I'm studing last level of Mechatronical engineering, I dont know to much of aerodinamics, you are right, but I have little notions of fluid mechanics.

As you can se my design is not complex or laborius. I'm using really trash materials with a reduced budget, using much home things. All materials are relatively inexpensive.

I'm working alone on mechanical and electrical design, the computer is made by me indeed. My partner is help me perfectly with the assembly.

In general, I'm building a prototype similar to a japanese drone. Can not be better or similar, but I'm trying bould my own toy.

I've seen some ones like this sphere flying, I would like to try make one.

The stability control that I've done is not finished yet but soon I will be able to implement. For the moment I found that it can fly.

Thank you very much for your tracing.

Best regards.
STARFOXFAM is offline Find More Posts by STARFOXFAM
Reply With Quote
Old Apr 05, 2013, 09:14 PM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
I've been analysing your suggestions about the spoilers, and saw your comments in other post where you spoke about an smoke experiment.
I have trying analise and understand the concept. As I said I dont know alot of aerodinamics, but the elementary phisic explains....
I saw in you video the smoke lines from the bottom until the upper side. I try draw the smoke lines below.
STARFOXFAM is offline Find More Posts by STARFOXFAM
Last edited by STARFOXFAM; Apr 05, 2013 at 09:36 PM.
Reply With Quote
Old Apr 05, 2013, 10:04 PM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
In fact is a interesting effect. I understand that the spoiler take her position by the air flow. The upper air flow from the external side run to the propeller making a little vacuum that holds the the most internal end in the spoiler, parallel to the propeller like looks in your example video of spoiler.
In the lower side we have a little turbulent flow (sparseness) that dont make opposed force to the upper. For this the spoiler goes to the propeller.


In the pictures above you can se the positive forces in green, coming from all directions like a umbrella. The red vectors are negatives be cause the force applied goes in counter direction to the vertical thrust. For this the motor lose power apparently.

I think that when you use the spoiler, you control the air flow, eliminating the negative forces. But there is yet a orizontal forces applied from the outside to the center. As this forces are opposite there are neutralized (brown vector). This opposite forces lose energy, but the motor power is little bit bigger than the case without spoiler.

I think that making a duct that direct air from the upper side through the propeller until downside may get more efficiency in the motor power and give more vertical thrust. This exploits the motor power..... I hope......IŽll need try.

IŽll appreciate your comments about. What you think?
STARFOXFAM is offline Find More Posts by STARFOXFAM
Reply With Quote
Old Apr 08, 2013, 10:43 AM
Registered User
Joined May 2010
430 Posts
Hello Victor,

I'm happy to see that you have taken the time to investigate the spoilers. It is difficult to tell from your posting if you did the smoke test yourself or interpreted the test I posted under the Japanese ball drone.

Your analysis of the smoke test appears to be reasonably close to my analysis, although I can't be sure due to the difficulties interpreting your posting.

I was fortunate to have worked on another aircraft design that utilized the Coanda affect, in conjunction with a propeller. During these test I observe this inflow to the side of the propeller while smoke testing in a rudimentary wind tunnel. Subsequently I was prepared to identify how the spoilers worked on the Japanese ball drone.

The spoilers do not improve the thrust output of the propeller as you mentioned in your posting, the function of the spoilers is to act as an oscillation dampener. Since the Japanese ball drone is extremely short coupled, i.e. the distance between the center of gravity and the control surfaces is extremely close the craft has a tendency to overcorrect when a control vane is deflected, subsequently creating overshoot of the correction by the flight controller.

Sato utilized these spoilers as a mechanical means of dampening the pitch and roll oscillations. One thing that is very interesting is the fact that he does not mention the spoilers in any of his speaking engagements or documentation that I was able to track down. One person in Japan that attended a seminar displaying the Japanese ball drone in-flight noticed the spoilers and also noticed that no mention was made of their function or the fact that they even existed. It appears that the makers of the Japanese ball drone do not want others to be aware of the function and installation of the spoilers.

Sam clearly indicated that the spoilers improved the handling characteristics of the drones that he built. As far as I know he utilized the spoilers on at least two craft, perhaps Sam can give us some feedback on this thread about his feelings regarding the spoilers.

If you were to install a shroud around the propeller in place of the spoilers you may see a small improvement in the thrust output of your electric motor propeller combination, but this shroud will not have the stabilizing function of the independent spoilers.

Please refer back to the Japanese ball drone thread, I clearly describe their function, construction and purpose in detail along with a few rudimentary sketches to describe how they interact with the relative wind independently during various phases of flight.

The Japanese ball drone is the most sophisticated VTOL aircraft I have analyzed. It utilizes a control system that was adapted from guided missile technology. I used the term canarderon's to describe the function of these forward control vanes in conjunction with the aft control means. This control system is similar although not an exact copy of how a Sidewinder missile is controlled.

In fact on RC groups there is a Sidewinder missile forum thread that shows the development of a simple Sidewinder missile. Towards the end of the thread on page number 45 you will see some videos of the Sidewinder missile set up as a VTOL. This is the best VTOL RC model I have ever seen. It uses a very simple control system, but if you were to install your much more advanced control system and activate the forward vanes to work like the Japanese ball drone it would have even better performance. This would be an excellent prototype and development design for your control system. Once you have flown the craft under stable flight conditions then you could shorten the fuselage until it resembles the Japanese ball drone. At that point you could wrap a cage around the outside.

In brief if you were to copy the Sidewinder missile as described in the RC groups form, install control vanes on the forward canard surfaces as well as utilize the aft control surfaces, employing a canarderon control mechanism as utilized on the Japanese ball drone i.e. and articulated control system, where the forward vanes move in the opposite direction as the aft vanes for pitch and roll and all eight vanes are utilized for Yaw control, you would have an exceedingly maneuverable VTOL and a very stable camera mount. Later if you choose you could shorten the fuselage incrementally to achieve a lower aspect ratio of the fuselage to control surfaces, eventually making it into a sphere shape if so required.

I think this would lead to much more enjoyment on your part, sense you would not be developing an extremely complex airframe and a complex flight control system simultaneously.

Here is the link to the Sidewinder missile thread
http://www.rcgroups.com/forums/showt...light=crazybal

Mini Sidewinder AIM-9 RC Missile - Fun Flying and VTOL (4 min 2 sec)
corocopter is offline Find More Posts by corocopter
Last edited by corocopter; Apr 08, 2013 at 10:48 AM.
Reply With Quote
Old Apr 11, 2013, 01:24 AM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
Ok, now I can understand the true function of the spoiler!! Thank you for your detailed explanation. I work today in a new design including the spoilers and as you said moving the GC. I give more material to structure and include more carbon fiber rod to reinforce them. At the moment IŽll dont use expensive materials, but if it works fine finally, I could improve the materials. I think in the posibility of use expanded poliestirene laminated with carbon fiber vinyl.

I apologize for my poor english, It should be a problem to understand my opinions or comments jejeje.
Thank you again.
STARFOXFAM is offline Find More Posts by STARFOXFAM
Reply With Quote
Old Apr 12, 2013, 10:20 AM
Registered User
Joined May 2010
430 Posts
Good morning Victor,

Your English is fine Victor, I only had trouble with a couple of sentences you employed to describe the airflow around the propeller. Your excellent vocabulary indicates that you are a highly educated and intelligent person. Please don't worry about your English skills I understand you clearly.

Your artwork is spectacular and extremely accurate.

Please reference the attached photo of the Japanese ball droning in flight. I'd like to point out a few subtle details that are important for you to employ in your current design.

Please note the location of the spoilers with relationship to the propeller plain of arch. You will see that the spoilers are approximately 8 mm below the propeller plain. This is to help facilitate the lifting of the spoilers up into the airflow allowing the spoilers to surf on the incoming air. It also sets the correct relationship to allow the spoilers to deploy downward when the sphere is moving in a horizontal flight maneuver.

Once again please reference the Japanese sphere photo below, you will notice that the right hand spoiler is deployed downward, dampening the forward flight moving in the direction from the right to the left. This deployed spoiler creates a differential braking force, the spoilers deployed preferentially around the diameter of the sphere in conjunction with the relative wind. Subsequently the spoilers work not only in a hover to dampen minor oscillations but they also deploy at higher velocities. The location of the spoilers with reference to the propeller plain helps to determine the deployment of the spoilers in conjunction with the application of minor weights added to the tips of the spoilers. This balancing the spoilers is a somewhat delicate process. Sam utilize small lightweight metallic washers super glued to the underside of the spoilers to adjust the spoilers.

Please reference both the photo of the Japanese sphere in flight and the photo of the Japanese sphere patent. Take note of the area of the lower vanes and fixed wing area, pay special attention to the fixed wing area as illustrated in the Japanese patent diagram (item #6 in the diagram). It is very important to realize that this wing area is required for high speed horizontal flight and the sizing and placement of this wing area is crucial. Since this aircraft is configured as a canard, the center gravity will be placed aft of the forward control vanes set and forward of the fixed wing area. The center gravity must be ahead of the Mean Aerodynamic Center (MAC). The Mac would be defined as the 25% aft of the leading-edge of a rectangular wing shape. The center of gravity for cruise flight should be somewhere around 20% aft the leading-edge, for hover flight the CG should be somewhere around 24 to 25% aft the leading-edge or almost exactly on the Mac. If you try to fly this craft in horizontal high-speed flight with the center gravity at 25% aft of the leading-edge the craft will be almost uncontrollable, at the very least very unstable. If you try to hover the craft with the center gravity at 20% of Mac it will be very difficult to hover. Having said all that, if you make the cord of the wing larger you will have a larger window of operating distance to move the CG forward and aft. Making the cord i.e. a “the wing area” larger makes the craft less sensitive to slight alterations in the CG location, additionally the additional wing area allows the craft to fly in horizontal flight at a reduced power setting which will extend the range of the device.

It's going to be rather tricky to figure out the exact location of the CG in forward flight, but in hover, testing will be relatively simple if you tether the craft and slowly move the CG upward and downward to ascertain its hover performance.

One way to make the CG adjustable would be to mount the battery on a rail or sliding bracket and slide the battery to and fro with a high speed digital servo. Servos can be made to run beyond their normal travel limit by slight alterations to create a Servo that works like a winch. If I remember right all you have to do is disconnect the feedback potentiometer, but I may be mistaken as to the finer details of that modification. It's been clearly described on the Internet several times.

Please reference the third photograph I posted of Sam's Taiwan sphere. Please notice the large lower control vanes and the noticeable offset in the vanes to compensate for the torque created by the electric motor. During the initial flight testing of your craft it will be necessary to implement offset in your vanes to overcome this motor torque.

Avionics:

The Japanese sphere supposedly has two 16-bit processors, I can only guess as to the utilization of these processors as one may be dedicated to work as the flight data controller, controlling the vanes in conjunction with gyros, linear accelerometers, and most importantly multiple magnetometers. The sphere clearly must be using an external reference for stabilization to achieve its remarkable hovering capability; I can only guess that it utilizes multiple magnetometers for this external reference.

The other processor may be utilized to control an inclinometer to automatically adjust and on-board movable weight to keep the center gravity accurately placed for various flight attitudes. I believe an inclinometer would be adequate instrumentation for the automatic center gravity control system.

Kelly
corocopter is offline Find More Posts by corocopter
Last edited by corocopter; Apr 12, 2013 at 10:32 AM.
Reply With Quote
Old Apr 12, 2013, 12:43 PM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
Ok, Kelly, thank you very much for the information, did not know some of these things for lack of experimentation but thanks to his previous work I will avoid these errors and modifies the design from the beginning taking care with these details.
For the control I'm working on, programing and designing all the mixers needed. Initially I'll use accelerometers and I'll prove to see the results, if it don't works fine I'll reach your recommendations. Why accelerometers? because I have them from other past projects jejeje. Remember... I'm using trash materials in order to don't buy more materials or less as can be possible.
I plan to use 2 controls... one for dedicated to control all servos and motor, and other for data processing, calculation and communications. May you can se the MCUs in pictures above.

I'm still repairing the structure and programming.
Analyzing your explanation of the flying type and the functions on the rocket (missile) for canard craft, I'll take the correct considerations for the mixers and movements in program.
Thank you very much again.
STARFOXFAM is offline Find More Posts by STARFOXFAM
Reply With Quote
Old Apr 12, 2013, 02:51 PM
Registered User
Joined May 2010
430 Posts
You're Welcome.

Maybe this would be of some help?

http://www.rcgroups.com/forums/showthread.php?t=1708175

Boards now cost just 20 dollars and the software is free. A huge amount off effort has gone into this software. A full IMU with gyros and lin/acc(s). A mixer is onboard too. A fast way to get flying for cheap!
corocopter is offline Find More Posts by corocopter
Last edited by corocopter; Apr 12, 2013 at 03:17 PM.
Reply With Quote
Old Apr 15, 2013, 05:02 PM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
Hi Kelly. Thanks for the recommendation.
Previously I had considered the option of use ArduPilot but needs additional sensors (gyro and/or accelerometers, magnetometers, gsp, etc).
I had bought before accelerometers and one GPS for other project, and I thought I could use them. OpenAero may cost $20USD but that do not include sensors and the software totally. Since I'll develop the software and I have ready the sensors, may be less expensive my integration.... I think....
Really in software and hardware (speaking about control system only) I spent less than $500MXP ($40USD aprox) considering that many parts comes from my stock jejeje.

On the other hand I spent aprox $80USD in my homemade FPV system (from scratch parts) and a little wireless camera (from RadioShack).
STARFOXFAM is offline Find More Posts by STARFOXFAM
Reply With Quote
Old Jun 04, 2013, 12:52 AM
Registered User
STARFOXFAM's Avatar
Mexico, JAL, Guadalajara
Joined Feb 2013
26 Posts
News!!!

Hi, IŽm Back!!!
Here information of last updates.
After a few days out of project, this contiunue.....
Here the temporal 2.0 version for testings.
STARFOXFAM is offline Find More Posts by STARFOXFAM
Reply With Quote
Reply


Thread Tools