Old Man Mike

Well, not exactly wheels but some of you might find this little mod interesting. I've noticed that during hard landings the HD motors take a beating on the exposed bottom area where the small braided wires and capacitors are located. I've often had a motor stop working after the braided wire became mashed flat enough to restrict the spring contact. In addition, a low throttle up can tilt the DF to the point where a blade can hit the ground. Both of these problems can be solved by using four plastic film canisters which have the ends cut away and a side cut of 1/2 inch to allow it to wrap around the motor housing. A couple of wraps of Black tape keeps it snug to the motor. The picture below should explain it all. The total added weight for all four protectors is less than 3/4 ounce. I was very surprised to find that the DF actually flew more stable with these four protectors. My best hovering time in the 8' x 8' room before the mod was 1 minute. I am now able to do double that. Here is a little video of the modification in flight: [link=http://www.af9y.com/draganflyer1.wmv]DFinside[/link]

When flying outside, the protectors seem to act as a shock absorber during a hard angle landing and help to keep the rotors out of the grass during normal landings and takeoffs.

Mike

kokomiko

Hi Mike

I think it is not a good idea to wrap the HD motors in anything at all as they are getting very hot.
Secondly, if you crash, all the force is distributed to the one motor you hit on and will more likely break the motor mount, or even the center cross, and will also not prevent the rotors from hitting the ground.
Have a look at my solution at http://www.rcuniverse.com/forum/m_5097494/tm.htm

BB_DF

Hey Mike,
Good flyin' man, in such a small area! I agree with kokomiko - the motors get hot enough already and don't need any encouragement.

When I was using the simulator I noticed it was a lot easier to fly if I sat the transmitter down on my knees, so my hands and fingers could stay relaxed. I decided to try a transmitter tray, and I really like it. A strap clipped on the front of the transmitter alone does not hold it securely enough for my liking, but the tray works perfectly. You can have the alertness of standing up with the stability of sitting down.

[link=http://www.qualityrcproducts.com/prod_transmittertray.html]HERE[/link],s where I ordered mine. I would suggest the one without the hand rests - it allows your hands to sense the edges of the transmitter, which helps maintain your stick/DF orientation, and is small and light.

Take care,
Bruce

Old Man Mike

Kokomiko,

I'll address your second point first. When the film canisters are cut into the slitted tube form, they are quite flexible. A shock absorber works by distributing the energy of an impulse over time. That is exactly what these protectors do. During an angled crash without the protectors, the very hard motor body takes all the force impulse and trasfers it to the frame. With the protectors that force is distributed over time and is less likely to damage either the motor or the frame. I had a 45 degree crash yesterday from aprox 30 feet with absolutely no damage. While that is not absolute proof (I put my faith in engineering principles) it certainly is encouraging. Of course an large angle crash will still allow the rotors to hit. The added rotor clearance I was referring to was for normal takeoffs and landings.

As for the HD motors. First, these motors are lightly loaded without the SAVS portion installed. Mine run warm to the touch after 10 mins of flight but certainly not hot. I could detect no difference in temperature by feel with the protectors vs without them. Remember that the canisters are cut as slotted tube so there is still air flow. Since you and others questioned the heat, I will make some direct thermal coupled temperature measurement to establish the real temperature difference. My personal opinion is that you are more likely to damage the motors from a crash without the protectors than from the small increase in heat.

Mike

BB_DF

Interesting. After 10 minutes mine are too hot to touch. I actually wouldn't mind having some black anodized heat sinks on them.

Sky High

Old Man Mike, couldn't you at least punch random holes in those cannisters with some hole punchers? I bet the plastic is thin enough for one to penetrate. DFI sells heat sinks for our motors. I used to fly with them but quit to save on weight as light as they are. I also didn't think they made enough different to matter. There is a thread discussing how someone actually performed a test with and without sinks with a heat measurer and said that the sinks did reduce heat when used.

BB_DF

I thought the heat sinks were not available for the HD motors, though the black color will radiate heat better than silver. They do seem to cool down pretty quickly.

Sky High

I assume they would fit both because the HD motors fit the same motor mounts.

BB_DF

You would think so, but they only have one heat sink and it says this at the bottom of the page:

Note: These heatsinks will work with the standard silver motors used on the Draganflyer VTi and VTi Pro.
Will not work on SAVS heavy duty motors.

kokomiko

Old Man Mike

Hm...after a battery worth of flight (8-12 minutes) my HD motors are also to hot to touch as BB_DF mentioned (I think it depends also on the weather conditions because when you (or the Ti) have to fight against wind, or it is very hot outside, the motors have to work harder). But it will be interesting to see the results after the measurements.

BB_DF
I bought the heat thinks (the green ones) but could not use them because they are to long? and stand over by app. 3mm, therefore touching the power connections and the capacitors.
You could cut of a quarter to shorten them though, but the combined weight of them is 37grams also!

Old Man Mike

Ok guys, I spent some time today testing with a thermalcouple attached to one of the motors and a temperature monitor mounted to the battery platform (see attached). Here are the results:

No Motor Protectors after 1 min flight (average of 3):
- 11 F deg rise at end of 1 min
- 17 F deg rise (peak) aprox 1 min later after motor shutoff

With Motor Protectors after 1 min flight (average of 3):
- 14 F deg rise at end of 1 min
- 21 F deg rise (peak) aprox 1 min later after motor shutoff

After looking more closely at the the motor design, I can see that the real cooling comes from the air passing thru the motor. Heatsinking the motor case does very little to cool down the temperature of the motor windings and magnets since there is a high thermal resistance between those components and the case. The protectors do not restrict the air flow thru the motor which is why there is only a 3 to 4 degree increase of motor temperature. Notice that there the temperature rise after stopping the motors is about twice the increase from adding the protectors. If you really want to reduce the maximum temperature levels for the motors just spray some compressed air into the top of each motor after landing. I tried this and it immediately stopped the post flight temperature rise.

By the way, I was able to fly inside my 8' x 8' test area for a continuous 5 mins with the motor protectors. I could only do a little over 1 minute without the protectors due to higher instability (I need to understand if this is due to the added weight at each motor or if there is some aerodynamic effect of the tubes that increase the stability). Anyway the temperature rise peak after the 5 min flight was 44 degrees. I believe that 140 degrees is the approximate point at which motor life begins to suffer so flying in the upper 90's might become a problem. Again, you can help things a lot by just spraying compressed air in the tops of the motors after landing.

Finally, I think that a small funnel expansion at the top of the protectors might actually provide increased cooling compared to no protectors. Not sure how it could be fabricated. But for the time being, I'm sticking with this simple approach to protecting the DF during the hard landings along with gaining that additional stability.

Mike

BB_DF

This is a valuable observation! A can of Dust-Off might help significantly prolong motor life.


Hmm, I don't know. Flying is 95% subconscious, and it might just be the new gear is giving you a bit more assurance. Learning to fly is like learning to play a musical instrument. You have to consciously analyze the process at the beginning, but eventually you have to get your conscious mind out of the picture in order to progress further. You DO have to observe, but as Sky High says, "You don't have time to think". It's a weird thing when one day you discover you already know how to fly if you can just get out of your own way. The musician hears a musical phrase in their head, and their fingers play it. The 3-D heli pilot thinks of the whole maneuver, and not each movement of the sticks. But in both these cases they practiced endlessly until they didn't have to think about it. Yitzak Perlman would practice his violin scales while watching television - heresy!

I think your best bet is to learn to use the Ti and practice outside in calm conditions. Land and rest every couple of minutes, even if everything is going fine. I think you'll find it's much easier hovering at waist level over grass because you won't be fighting your own vortices, and if you panic, just chop the throttle and land. Do what builds your confidence, even if it's just hovering nose-out for hours, but try to get a little more control each time you fly. When you use Ti, take a small thin board, like masonite, and when you set the thermal levels (throttle down & right), do it on a level spot out in your yard, away from the driveway and house. This will reduce the amount of trimming needed. You already know how to fly, what you need now is just a little more confidence.

Cheers,
Bruce

Old Man Mike

I agree that this could be happening so I'm trying to come up with some sort of test to prove it. I've tried close trimming and then letting go of the joy sticks but there is too much variablity in the time before I have to return to flying it. (But I swear it seems to be a longer period with the protectors on.) One approach I am considering is to buy a Berg receiver module and record the servo outputs with a 4 channel a/d converter from that receiver while hovering the DF inside. It should then be possible to compare the peak to peak and average corrections of hovering with and without the protectors. (I guess 30+ years of engineering design is coming back to haunt me.) If this works, I will be able to make accurate measurements of any modifications made to DF relative to stability.


You've just described exactly what I have been doing as often as low winds permit. I find myself now flying in active mode rather than training but still have occasions when my fingers seem to be in an ackward position or strained while doing some of the movements.

---------

Also, thanks to Sky High for the comments on my indoor flying. I've spent a lot of time reading your excellent posts.

Mike

BB_DF

Mike,

I'm really just learning too. Here are some ideas that have helped me to focus and stay oriented:

Quantized Movment:
I've found that the real progress starts when you get rid of the original idea of the heli moving in the same direction as your stick, and instead start imagining how the heli is going to react when you move the stick in a certain direction. First, think and move only in the cardinal directions - forward/aft, left/right - "don't mess with mister in-between". You can combine actions, but it is simpler to think of only 4, rather than an infinite number of directions. This works well with the DF - four rotors, four directions. Then make small, but quick "quantized" movements for correction, preferably in anticipation of movement. Make a repeated series of small, quick corrections in the same direction if necessary. It's fairly easy to hover within a 1 foot area this way.

Universal Orientation
Think "when I push the stick forward, the nose rotor drops" - true in any orientation - rather than "when I move the stick forward the heli moves that way", which requires an additional level of thinking unless you're exactly tail-in. Likewise, regardless of its heading, think to yourself "if I move the stick to the right, which rotor is going to drop?". So when you need to correct, you know in advance what you need to do because you've already imagined it in your mind. You start thinking about what the heli needs to DO, rather than what DIRECTION it needs to go. For instance, as you fly near an obstacle, think to yourself "what stick action(s) will get me away from the object". This helps you to relax and gain confidence. It's like thinking in the native language, rather than translating everything from one language to another in your head first.

I also have a really easy mental trick that I use to hover nose-in, but that's enough for now.

Having said all that, I would recommend a right-brain (non-analytical) approach to this project, once you understand the basic rules. Retired engineers learning golf etc., tend to analyze 'til paralyzed. You'll have a whole lot of data but still not have any confidence. (It takes one to know one - I'm EE '81).

Ciao,
Bruce

Sky High

Yes, I've done that a couple of times but canned air is not that cheap. Also, the kind that Wal-Mart sells has a bitter additive to prevent people (mostly kids) from sniffing it. Just rub your mouth after letting some of that air get on your fingers and yuck! I would think that would leave a residue of some kind too. I mostly just blow air from my mouth in the motor vent holes because I've got plenty of air to spare with all the mouth running I do, not to mention it's free.


Very well stated BB_DF, especially the Universal Orientation method. That's exactly how I learned so fast. Not thinking about a two step process of stick input and reaction but only what the action was as if I was onboard. I started nose IN and have always flown better that way.

Old Man Mike

OK, I'm ready for that trick. I seem to be doing very well now with tail-in flying and have found that your recommendation about concentrating on rotor movement rather than body movement quite helpful. But the nose-in flying is still very difficult for me. I know that part of the problem is that I can only practice in the 8' x 8' area which allows very little recovery time for mistakes. While I can now do tail-in flying in the room until the battery runs out, I can't fly nose-in more than a few seconds. Also, after a lot of nose-in practicing I find it degrades my tail-in flying ability for a while. Maybe that is an indication that I'm still flying more by body movement than rotor movement.

I have to ask, why nose-in first? I thought everyone normally starts tail-in. Did you do this intentionally as a way to avoid bad habits?

Mike

Sky High

Like you mentioned and as I said in [link=http://www.rcuniverse.com/forum/fb.asp?m=3621880]this[/link] post, it really helps to be in an open area with practically no wind and perfect Ti so you can actually experience continuous controlled flight with long linear approaches and smooth bank turns to get a feel for the response and have more time to recover because of the open space. The DF will fly just like a plane and will do exactly what you tell it if you think of it like BB_DF described. Think of yourself as being onboard and you can't go wrong in any orientation unless you don't know where the nose is. I would highly recommend installing a nose and tail LED and fly an hour or two before dark so those LEDS show up really well. You would be amazed how much easier it is to learn if all you have to do is know that what ever color you choose is the nose and just think about where you want that nose to go and your hands will automatically do it.

BB_DF

Mike,
I'm sure different people have different approaches, but I agree with Sky High, I'd rather hover nose-in, because somehow it just seems more comfortable. Or maybe it's just because it's supposed to be so "hard", when it's really not. Anyway, here's my approach. The main thing is you don't have time to analyze reverse actions - your responses must be immediate and direct.

First, trim out your DF tail-in so that it lifts off evenly.

Your left stick will not change its function at all for throttle/yaw, so it's the right hand we will concentrate on. Keep the DF's beady little eyes looking directly at you at all times. This is important.

I consider the nose-in hover to be a SPECIAL CASE. The goal is simply to maintain the DF in a hover when it's facing me directly.

1. Say to yourself mentally: "NOSE IN RULES", whenever you're hovering nose-in, are about to enter a nose-in hover, and also periodically while you're in a nose-in hover. This is to establish, or re-inforce, the SPECIAL CASE RULES.

2. Now the "NOSE IN RULES" are incredibly simple: just MOVE THE STICK in the SAME DIRECTION as the DF moves. So if it starts to drift away from you, you move the stick away from you. As it comes towards you, move the stick towards you. As long as you keep the nose directly pointed towards you, move the stick in any direction the DF moves.

I think of this like it's dancing with the heli. Like dancing with a partner, you move in the same direction as she does. You will find that when you tell yourself "NOSE IN RULES", it becomes really easy to shift into this mode. It does not conflict with the "normal rules", because they have a completely different feel. When you have forward motion, like flying in figure-eights, it's pretty easy to stay oriented with roll, because it's more of a fluid set of movements. However, when you hover nose-in, it feels different, and you can easily get confused if you don't have a very simple and direct method of maintaining a stable hover. Remember to tell yourself "NOSE IN RULES" frequently, and keep your focus on the simple set of correcting responses.

The "NOSE IN RULES" are a tool that you can fall back on at any time. Once you've done it enough, it will begin to blend with the "Universal Orientation" concepts, but if and when this happens is not important. Once you start to feel comfortable with it, it has sort of a mesmerizing effect.

Hope this helps.
Cheers,
Bruce

Sky High

We're getting way off topic but isn't it fun? The DF sure enough has some beady little eyes but the more the better to navigate with. In addition to a nose and tail light for perpendicular flight orientation, some wing lights really help to let you know real quick when you are nose in, even at 100+ yards. Believe it or not, because it scared the $%#@ out of me, I've have sent the DF at least 200 yards away and when I banked around those LEDS looked just like a full size jet off in the distance on final approach. [8D] You can see how effective they are in the video in [link=http://www.rcuniverse.com/forum/fb.asp?m=3813997]this[/link] post and a more and higher twilight flight video in [link=http://www.rcuniverse.com/forum/fb.asp?m=4077895]this[/link] post with additional stills [link=http://www.rcuniverse.com/forum/fb.asp?m=4077910]here[/link].

Old Man Mike

I've considered putting on the LEDs but keep thinking that they would not show up in bright daylight. I suppose I should give it a try. In the meantime, I'm using some bright colored reflective tape on the frame and on the training protector tubes. It is really easy to see even when lighting is poor. By the way, one other advantage with the protector tubes is that you can move the DF around the carpet like a car since it does not allow enough tilt to restrict movement. That helped a lot during early training since you can get a feel for the movement without actually hovering.

Mike

Sky High

LEDs are useless in bright sunlight. Flying right before dark has advantages other than highly visible nav lights such as the significant decrease in wind and on clear evenings Ti calibrates perfectly.