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Old Jun 12, 2012, 08:48 PM
Sopwith Camel's Cousin
Between my tx and crashed aircraft
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Originally Posted by Ken41 View Post
My thoughts are, that a fair number of RC pilots that have not learned to fly a full scale AC, or been have been in the aviation industry, do not understand that the horizontal stabilizer / elevator controls pitch / airspeed. The throttle controls altitude
...
I never did fly at even close to full scale (heaviest aircraft is about 1 pound), but I got a fair dose of this from trying to learn harriers and from hand-launching planes (plane loses altitude after I let go until it has accelerated to a fast enough airspeed).
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Old Jun 12, 2012, 11:17 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
The closes I've got are a Parkzone P-47 or F4F. The P-47 has a semi-symetrical airfoil and is loaded down with retracts and flaps. The F4F has a flat bottom airfoil and is hand launched. It's also been in a more crashes than the P47. It's frame and wings have been glued back together a few times. Take your pick.
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Old Jun 13, 2012, 12:19 AM
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"Take your pick"

I'd say either one should tell us what we want to know. Does either one have a particularly dramatic stall such that you can't miss it when it happens ?

Dick
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Old Jun 13, 2012, 12:52 AM
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Berkley, MI
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Originally Posted by otrcman View Post
"Take your pick"

I'd say either one should tell us what we want to know. Does either one have a particularly dramatic stall such that you can't miss it when it happens ?

Dick
Let me sleep on this one.
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Old Jun 13, 2012, 10:00 PM
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United States, PA, Clarksville
Joined Aug 2006
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Joel,
RC in the warm weather and Ham radio when it's snowing!

choochoo22,
I think that it is difficult for someone that has not had a chance to fly a full scale to visualize what takes place with the the throttle verses the elevator. Your explanation is great. Your flight instructor sounds like she is right on.

Ken
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Old Jun 13, 2012, 10:03 PM
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Berkley, MI
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Quote:
Originally Posted by otrcman View Post
"Take your pick"

I'd say either one should tell us what we want to know. Does either one have a particularly dramatic stall such that you can't miss it when it happens ?

Dick
Details:

F4F: In it's current state there are three individual head holding helicopter gyros installed. Let's leave this one as is for now since we can use it for further testing. It does everything you'd expect 3 individual gyros working independently.

P-47: In its current state it has an FY30A that is being moved forward nearer the CG - this is to balance a T1000 Telemetry tx. So it's being rewired at the moment. I've been very satisfied with the FY30A. It only has 3 modes...OFF/3D/Stabilized. For scale flying I fly mostly in 3D mode with max gain on the ailerons, and low gain settings on the rudder and elevator. Higher settings on the rudder and elevator and they will hold orientation which doesn't look well on a scale like plane.

Let's go with the P-47, so that we can also compare the FY30A's stability mode to the Guardian.

I'll see if I can get it rewired and ready by this weekend, and we'll start with the FY30A.

Reference:
http://www.rcgroups.com/forums/showp...postcount=1678
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Old Jun 13, 2012, 11:06 PM
Static Model Collector LOL
Katy, TX
Joined Dec 2009
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Originally Posted by Aero65 View Post
Hello All
I was able to load up the PC interface for the Guardian and do some additional testing this weekend.
Sorry no additional video my friend was out of town that usually videos.

Test 1: Ability to change, servo update rate with PC software. Most digital servos update at around 250 Hz, most analog servos about 50 to 70 Hz (Guardian default 50 Hz, the Futaba GY-401 analog setting is 70 Hz). In my F-4D I have Futaba S9156 servos on the elevons, and a JR DS368 servo on rudder (DS386 = 300 Hz update speed). I did not know the Futaba update speed but knew it was at least 250 Hz, so I set the Guardian at 250 Hz.

You must be careful when changing this setting you must use the lowest servo refresh rate of all you servos connected to the Guardian. If you had 2 digital servos and 1 analog for instance you would need to set it at 50 Hz, the digitals will work fine at this setting. If you try and run an Analog servo at a higher refresh rate than it can handle it will burn out.

Results: Two weeks ago, at 50% master gain the F-4D oscillated in roll, now at 250 Hz I was able to fly at full throttle at that gain without oscillation. Another effect was now my roll control was much more dampened and the overall effectiveness of the gyro was better. I did feel with the increased gyro effectiveness it felt like you had to really push the controls, this is where direct rate would be great.

Test 2: 2D mode recovery from unusual attitudes.

Method 1: Roll inverted recovery. Ok put Guardian in off position, then rolled the F-4D inverted (1.5 split S high just in case) activated 2D, it very, and I mean very quickly rolled upright and level no overshoot totally impressive, I will get video of this next week.

Method 2: Pitch straight up. Guardian off pulled F-4D into vertical climb turned 2D on plane pushed over leveled out non issue.

Method 3: Vertical dive. Guardian off pulled F-4D into loop on backside of loop pointing straight down turned 2D on plane pulled up leveled out non issue.

Conclusion: Testing went normally, the increased resolution that was available to the digital servos when you turn up the update speed was impressive, settings that resulted in oscillations at 50 Hz were rock solid at 250 Hz. The decreased control authority due to the Guardian working better really made me want to test direct 3D rate but did not have the time to set it up properly so that will have to wait for the upcoming Sunday.
Good stuff aero, pretty sure this write up saved a few planes already

What voltage are you running the servos at, I tend to use with HS5085MG or HS5065MG at 6V

From the limited info that is available, I saw a screenshot of what an artificial horizon, I assume this is used to setup the models level profile, please confirm.

BillPA - any chance of an early release of the manual?


Al - if I recall you tested this in a Stryker Q, do you recall the gain settings

Thanks,

FCA
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Old Jun 14, 2012, 12:32 AM
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I went back and watched Silverexpress' video of his P-47 with the FY-30A installed. It reminded me of something I wish I'd said long ago to people who scoff at flying with a gyro.

One of the reasons I like using a gyro is that the plane looks much more realistic in flight. Gone are the quick little bobbles which a model always does in response to atmospheric turbulence. Models with gyros seem to fly a lot more like their full sized counterparts.

Dick
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Old Jun 14, 2012, 02:57 PM
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Honolulu
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Hi Flame 747, and Otrcman thank you it’s good to hear that what I’m doing makes sense, good feeling that I can give a little back to the community.

I’m really glad that Eagle Tree has opened up so many parameters that you can change on the Guardian. It really makes it useable for the beginners and the power users.

For the voltage I run a 2S lipo connected to a Fromeco regulator and I have it set to output about 5.8 V there were no issues with any jittering at all.

The artificial horizon on the pc app is to show you your current set attitude. Set by either a button on the application, or within 15 sec of turning the receiver on by moving your mode switch full fwd and back or the other way round. The servos will twitch once to indicate resetting of level flight attitude, and trims.

To reset just the trims you click 2 times and the servos will twitch twice.
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Old Jun 14, 2012, 03:02 PM
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As a comment where I fly the ground is not exactly level in our pit, I think I will bring a level to the field so when I set the flight attitude it’s pretty close. I think you can eyeball within 2 or 3 degrees however you might also be thrown off by the fact that you’re comparing it with non-level ground.

You also have to have a good sense for the nose up attitude of your aircraft in level flight. For example my nose gear on the F-4D is pretty high so if I just sit the plane on its gear it climbs in 2D at normal cruise. So when you set level flight mode you have to be pretty close to the normal level flight deck angle.
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Old Jun 14, 2012, 04:58 PM
Sopwith Camel's Cousin
Between my tx and crashed aircraft
Joined Mar 2006
3,802 Posts
Quote:
Originally Posted by Aero65 View Post
As a comment where I fly the ground is not exactly level in our pit, I think I will bring a level to the field so when I set the flight attitude itís pretty close. I think you can eyeball within 2 or 3 degrees however you might also be thrown off by the fact that youíre comparing it with non-level ground.
...
One thing about levels: some of them may be a little off also. With what some of my levels call "level", rainwater definitely wants to travel in a particular direction.
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Old Jun 14, 2012, 05:41 PM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Originally Posted by flying-llama View Post
One thing about levels: some of them may be a little off also. With what some of my levels call "level", rainwater definitely wants to travel in a particular direction.
Agreed. With the level in my 'Droid I found the readings too inconsistent to use for setting the tail incidence on my Polaris.
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Old Jun 15, 2012, 12:14 AM
Static Model Collector LOL
Katy, TX
Joined Dec 2009
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I wonder if the guardian would freak out
When used in a plane that is catapult launched

Probably best to launch with it off, gain some altitude the go to 2D

Beta testers any thoughts

FCA
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Old Jun 15, 2012, 01:27 AM
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Great White North
Joined Jun 2008
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Quote:
Originally Posted by FLAME747 View Post
I wonder if the guardian would freak out
When used in a plane that is catapult launched

Probably best to launch with it off, gain some altitude the go to 2D

Beta testers any thoughts

FCA
I have bungee lunched it no problem - just make sure gains are not too high. Generally the bungee builds speed slower than a hard hand toss so i have not had any issues - but test out initially with LOW gains and increase as necessary from there.

I have not had any problems with bungee on the guardian add on version either

Al
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Old Jun 15, 2012, 04:05 AM
Rick
United States, CA, Santa Clara
Joined Mar 2011
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Quote:
Originally Posted by FLAME747 View Post
I wonder if the guardian would freak out
When used in a plane that is catapult launched

Probably best to launch with it off, gain some altitude the go to 2D

Beta testers any thoughts

FCA
I would think you could set up the catapult at a good climb angle, set 3D mode, and launch hands-off. Don't touch it until you get to altitude. Testers, wouldn't this work?
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