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Old Jun 17, 2012, 11:56 PM
Team JetiUSA
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Santa Clara, CA
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From the radio you only have control over the master gain, which is the multiplier for all 3 gain axes, so you could mix a gain reduction in from gear or have landing mode change the output of your gail channel, but you can't affect just Ailerons.


Peter+
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Old Jun 18, 2012, 08:41 AM
Static Model Collector LOL
Katy, TX
Joined Dec 2009
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DavidN - why would you want low gain for landing, I assume most would opt for a high gain setting during approach and landing.

To optimize guardian for our planes, we are all going to have to do some adjustments over several flights.

Initially I plan on setting up a slider on my JR9503 to control the gain, eventually the optimal gain setting will be mapped to the flight mode switch, using the gyro sub menu to control the gain, David you might want to look into this option.

FCA
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Old Jun 18, 2012, 10:42 AM
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Vernon, BC, Canada
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To avoid large aileron movements, risking inducing stall of 1 wing.
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Old Jun 18, 2012, 02:26 PM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Quote:
Originally Posted by DavidN View Post
To avoid large aileron movements, risking inducing stall of 1 wing.
This might require some in-flight observation at a safe altitude to verify, but I would expect one of the benefits of the Guardian is that by maintaining tight control of the attitude, large deflections wouldn't be necessary. Unless, of course, hit with a large gust at low speed which could always be dangerous no matter what you do. Using digital servos and a fast refresh rate and high gain might help in making sure it never gets far enough out of line to need a large deflection.
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Old Jun 18, 2012, 02:29 PM
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Berkley, MI
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Originally Posted by otrcman View Post
Silver,

I'd suggest an airplane of fairly conventional shape -- Piper Cub or P-51 style should do fine. It shouldn't be a flat foamie, though, because flat plate wings don't have the same stall characteristics as wings with airfoils.

The plan would be (in 2D mode) to establish a steady, level flight at cruise or full power. Then chop the throttle to zero power. Watch the airplane to see if it noses down in the descent or does it try to hold the nose level as if it still wants to maintain cruising flight.

If the nose remains in a level flight attitude, but the descent angle gets steep enough (10 or 15 degrees), the wing will probably stall.

DavidN,

In your post, you said, "If stall is solely related to angle of attack (& wing loading)......" You were right on the money until you added wing loading. Wing loading has little or nothing to do with stalling angle of attack. If anything, the same airplane at a lower wing loading may stall at a slightly lower angle of attack.

Think about it this way: You go out to the airport and notice a row of airplanes parked on the ramp. They are all facing the same way, nosed directly into a 10mph breeze. There is a Bonanza, a Mig 21, a Cherokee, and a Piper Cub. Which airplane, if any, is stalled in this light breeze?

Answer: Only the Piper Cub. Not because of its airfoil, or its wing loading, or the low airspeed. Only because it is sitting tail down such that the wing is at or above its critical angle of attack. If you put tufts on the wings of all these airplanes, you will see smooth airflow over the Bonanza, Mig and Cherokee because their wings are at low angles of attack. But the tufts on the Piper Cub will be showing separated airflow.

Now, are any of these planes making lift in the 10mph breeze ? Yes, all of them. But not enough to fly.

Now, imagine the wind speed increases to 60mph. Which airplane will tug at its tiedown chains, trying to fly ? You guessed it, only the Piper Cub. Even though the wing is stalled, it is still making some lift, and that's enough to overcome the weight of the airplane. The Bonanza and the Cherokee would probably try to lift off if you put a jack under their nosewheels and raised the nose 10 degrees or so. The Mig ? Forget it, wing loading is too high to make enough lift even at 60mph.

Dick
Hello Dick,

Here is the written conclusion.

Test Flight: Fly level, cut throttle and pitch up.

F4F with three seperate helicopter type gyros: snaps into a spin and dives when in head holding mode. In Rate mode, the aircraft just goes into a dive.

P47 with FY30A: Stalls, dives and then goes into a glide. Sometimes though it just reaches a noticeable angle in the roll direction - as if the sensitivity was not high enough to detect it had not yet reached level in the roll axis.

P47 with Guardian: Stalls, dives and then goes into a glide. It's much more responsive than the FY30A in getting it's roll axis back to level and it's pitch axis back to the user's set angle.

The main thing here is that the FY30A and the Guardian 2D/3D both have software that ties in all 3 gyros and accelerometers. It's like having preprogrammed mixes that include these sensors, and their input/output.

In contrast, the F4F has three independent gyros that are not programmed to "level" the roll axis of the plane. Nor is the elevator gyro being driven to attain the pitch angle that the user had set. Because they work independently, they can lock their corresponding control surface to a certain orientation. You have to be very careful to fly such a plane, and must consciously coordinate each control surface especially in a slow banked turn with head holding active on all 3 independent gyros. My preferred setup for this F4F is to fly the ailerons in Head Holding (as highest a gain that can be set without oscillations), and the elevator and rudder in Rate mode (with very low gains).

Lastly, in my Twister 480, I've gone from 3D mode to 2D mode in every attainable orientation, and never once did the plane go into a spin. It always leveled out and glided. In contrast, I don't use the Stabilization mode of the FY30A in the P47. It does not have the type of override that the Guardian has - making the aircraft difficult to bank or pitch - essentially turn. You definitely want to be clear of tree tops when flying the FY30A in Stabilization mode.
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Old Jun 18, 2012, 04:31 PM
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So when will this be available? Cant find it anywhere
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Old Jun 18, 2012, 06:05 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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The first shipment for those who pre ordered months ago should ship any week now. That group is sold out. Next shipment should be in August.
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Old Jun 18, 2012, 06:49 PM
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The wait drags on..... :(

Thats more like late summer..... not late spring as advertised?
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Old Jun 18, 2012, 07:39 PM
Team JetiUSA
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Santa Clara, CA
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Originally Posted by Chris.Williams View Post
Thats more like late summer..... not late spring as advertised?
June 21 is the start of summer. If Bill ships this week it's late Spring :-) I'm hoping to see a ship notice!

Peter+
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Old Jun 18, 2012, 07:54 PM
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United States, FL, Gainesville
Joined Nov 2006
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Well better late than never... I finally got out of the tropical storms, rain, humid nastiness, and being stuck working to get out and get my 72in 3DHS AJ Slick up with the guardian installed. And I didn't even drop my radio in the dirt this time. Here goes... Wind was very gusty, and about 14-45mph. It was blowing exactly 90deg across the runway at my club field. I'll be honest, even though I've flown some other planes with the Guardian in winds worse than this, I was really apprehensive. I mean this is my favorite plane in my trailer. It was previously owned by the man himself (AJ), and he signed the inside of the cockpit, so it's got a little extra cool level in it. It's windy as hedoubletoothpick and the gusts are erratic. But I dropped the tail of the trailer and put the wings on, dropped the 6S5000 in, balanced, and taxied out.

First feelings on this plane with the Guardian in it is wow, or should I say WOW! This plane on high rates is normally a butt-puckerer. If you're not on top of it when flying low, it'll catch you off guard because the rates I run on it are slightly higher than recommended. This was completely not the case with the Guardian 2D/3D stabilizer installed. I first did some putt aroun flying in 2D mode and some elevators into the wind. Even with he wind gusting erratically there was virtually zero wing rock. I mean if you concentrated on it you could see it ever so slight, but that was it. During fast passes I got a little flutter, but I think next time I go out I will mix gain to throttle and try to put a curve to match it. I did not have a lot of time to mess with radio today because I wanted to get a couple flights in. I goofed with 3D mode a little then popped it into 2D mode and let it elevator drop all the way to the ground. Landed with a gentle plop. I can do that with some of my other planes but not this one.

I swapped out to the second battery and this time spent the whole flight in 3D mode (except for takeoff). It figures I had no one to film me because the whole time I was flying I was kind of hoping just one pilot would see me kicking this Slick around like I was a master. Knife edges into the wind were true and no wiggles. The plane tracked straight as an arrow even when it was low and slow. A fast knife edge gave me a little flutter, but the Guardian seemed to back the gain down on it's own and the flutter tapered off. Hovers were solid and I probably had the hover hanging lower than I've ever doe it before but some really raunchy gusts were tipping it over a bit because of the nice wing area on that plane. Hard snaps were a little mooshy with 3D mode enabled but I think that can be addressed in the radio. They are not like that in bypass mode. The EagleTree head dev guy is really good with suggestions on stuff like this so I am asking him to see what he suggests.

So all in all I was very impressed. I actually think it was even better in this plane than in some of the smaller ones that I tried it in. When the ones I ordered arrive (I also plan to order 2 more), I will likely have one in this plane for those windy days like this and practicing new moves. Plus, landing in gusts to me is the most challenging thing about RC flying. The Guardian made landing in these gusts a non-event. I even tempted it by pulling off a few more landings just for fun.
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Old Jun 18, 2012, 08:29 PM
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United States, WA, Kent
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Quote:
Originally Posted by pvogel View Post
June 21 is the start of summer. If Bill ships this week it's late Spring :-) I'm hoping to see a ship notice!

Peter+
I talked with them tonight just because Iím getting anxious and it sounds like we still have to be patent. I was told probably another two weeks.
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Old Jun 19, 2012, 12:04 AM
Your customer
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Berkley, MI
Joined Dec 2009
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How about a station break while we wait for our pre-orders to ship ....

FPV takeoffs and landings....
Cub Takeoffs and Landings (4 min 51 sec)


On board fire
Piper Cub ESC Fire (2 min 46 sec)
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Old Jun 19, 2012, 01:01 AM
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Quote:
Originally Posted by Silverexpress View Post
Hello Dick,

Here is the written conclusion.

Test Flight: Fly level, cut throttle and pitch up.

F4F with three seperate helicopter type gyros: snaps into a spin and dives when in head holding mode. In Rate mode, the aircraft just goes into a dive.

P47 with FY30A: Stalls, dives and then goes into a glide. Sometimes though it just reaches a noticeable angle in the roll direction - as if the sensitivity was not high enough to detect it had not yet reached level in the roll axis.

P47 with Guardian: Stalls, dives and then goes into a glide. It's much more responsive than the FY30A in getting it's roll axis back to level and it's pitch axis back to the user's set angle.

The main thing here is that the FY30A and the Guardian 2D/3D both have software that ties in all 3 gyros and accelerometers. It's like having preprogrammed mixes that include these sensors, and their input/output.
.
Hi Silver,

Thank you for your report. One thing I wasn't clear on. In your report, you said, "Test Flight: Fly level, cut throttle and pitch up". Did you intentionally pitch the airplane up with an elevator command or did the airplane pitch up by itself ?

My original premise was as follows:

1. Fly level at cruise or full throttle in 2D mode.

2. Chop throttle, but make no other inputs.

3. Observe model behavior. I suspect that the model will continue straight and level, but lacking power it will lose speed (Guardian will keep adding up elevator in order to maintain a level pitch attitude.) At some point, the airplane will lose so much airspeed in trying to maintain pitch level without power, that it will stall. Does it in fact do this or does Guardian 2D somehow lower the nose to allow the airplane to maintain flying speed ? A normally stable airplane without stability augmentation can be expected to pitch down all by itself because it will try to maintain a constant angle of attack rather than a constant attitude.

This was a flaw that we found in flying the NASA PA-30 in attitude command mode. The airplane was marvelously docile to fly as long as power was kept between mid range and full. Adding or reducing power simply resulted in a speed change without an attitude change. But when we reduced power to the point that the airplane needed to nose down to maintain a safe speed, it would stall because the control system kept trying to maintain a level pitch attitude.

Dick
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Old Jun 19, 2012, 01:09 AM
FPV junkie
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United States, UT
Joined Jan 2011
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Silver,

Glad your plane didn't burn up. That was crazy.


I noticed you still had power to the Rx, did you have a secondary BEC, or were you still getting power from the burned ESC?
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Old Jun 19, 2012, 01:10 AM
Your customer
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Berkley, MI
Joined Dec 2009
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Quote:
Originally Posted by otrcman View Post
Hi Silver,

Thank you for your report. One thing I wasn't clear on. In your report, you said, "Test Flight: Fly level, cut throttle and pitch up". Did you intentionally pitch the airplane up with an elevator command or did the airplane pitch up by itself ?

My original premise was as follows:

1. Fly level at cruise or full throttle in 2D mode.

2. Chop throttle, but make no other inputs.

3. Observe model behavior. I suspect that the model will continue straight and level, but lacking power it will lose speed (Guardian will keep adding up elevator in order to maintain a level pitch attitude.) At some point, the airplane will lose so much airspeed in trying to maintain pitch level without power, that it will stall. Does it in fact do this or does Guardian 2D somehow lower the nose to allow the airplane to maintain flying speed ? A normally stable airplane without stability augmentation can be expected to pitch down all by itself because it will try to maintain a constant angle of attack rather than a constant attitude.

This was a flaw that we found in flying the NASA PA-30 in attitude command mode. The airplane was marvelously docile to fly as long as power was kept between mid range and full. Adding or reducing power simply resulted in a speed change without an attitude change. But when we reduced power to the point that the airplane needed to nose down to maintain a safe speed, it would stall because the control system kept trying to maintain a level pitch attitude.

Dick
Uh-oh. I pitched it up. If I did not, it would just glide. The elevator is actively being controlled by both the FY30A and Guardian. They are trying to maintain a set angle in pitch, and likewise to attain level in roll. I was focused on getting it into an uncontrollable spin.

I'll try it again. The Guardian's pitch angle in 2D can be set between +-25 deg from what I understand. We'll try -10, 0, +10, and +20 deg. My thoughts are - if the controller is fast enough to detect even a minute change in the angle, and its output is coupled to a fast servo that is linked to an adequate sized control surface then the plane should not enter a pitched nose up stalled state, but harrier to the ground.

If anything, I would imagine that it would start gliding backwards - pusher with a canard!

I wonder why your test vehicle pitched upwards? Do you remember the sensors used and a summary of what the logic was in maintaining level flight?

PS. The video I took is pretty boring.

Update: It just dawned upon me - I'm a bit slow when it comes to these things - but these units do generate an aritificial horizon. See manual. From this data, they can condition the logic to maintain the nose of the aircraft at some limit above that aritificial horizon. This will prevent it from stalling. Anyhow, there's a lot you can do with software, and so it's a guessing game as to what the code actually does.

Reference:
Read thru some stuff during lunch...
http://diydrones.com/profiles/blog/s...omment%3A41399
http://forum.sparkfun.com/viewtopic.php?f=14&t=24226
http://www.x-io.co.uk/res/doc/madgwi...nal_report.pdf
http://en.wikipedia.org/wiki/Attitude_indicator

Motion Sensing Video Tutorial-InvenSense (3 min 27 sec)
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