Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[GliderGuy]

But are you flying around with flaps down (making the flap servos work hard) for an entire flight that includes several high speed passes?

Correct me if I am wrong... Servo holding current should be only a small % of stall current.

Follow me....

#1 Servo moves to commanded position and stops. If a load is applied, a slight increase of current will occur as the servo attempts to hold position.

#2 Servo stalls under heavy load attempting to move to a commanded position but cannot get there. Stall current = MUCH larger than #1.

Flying around with flaps down....once the flaps reach commanded position, should be more #1.

Am I missing something? About 1 min of my flights is with flaps down to commanded position (#1).

Another key thing....the MiG flaps are small surfaces. Logically, the loads imposed on the flap servos cannot be very large compared to flap servo drive capability. If this were an issue, the AL37 with smaller servos and large flap area would be having issues. It isn’t.

-GG

[mshagg]

About 500 flights

That's like 38 flights a day, every day, since release 😲

[GliderGuy]

Not really when you consider all the days that have passed since I got mine (first shipment). But I have had a few 40 flight days. What can I say....I love to fly and the weather has cooperated.

I was at 360 flights last month. So 400+ for sure.

I do at least 2-3 battery sets when I go out. 3 sets = 15 flights. I go out every day it is good weather. Sometimes twice a day. Beats watching TV.

Charging batteries for one set now....pre-work flights. Gets my mind sharpened for the daily grind and don’t wanna pass up this pretty morning.

-GG

I know....”Get a life!” LOL But at my age, gonna play all I can. Friends are passing....who is next?

[mshagg]

But I have had a few 40 flight days. What can I say....I love to fly and the weather has cooperated.

You're a machine! Happy flying in the morning.

[GliderGuy]

You're a machine! Happy flying in the morning.

Thank you. In this crazy COVID world, nice to have a diversion to keep one’s sanity.

COVID has kept me grounded from my true passion....flying sailplanes. Did I mention that I love to fly?

-GG

[HaroldAnderson]

Correct me if I am wrong... Servo holding current should be only a small % of stall current.

Follow me....

#1 Servo moves to commanded position and stops. If a load is applied, a slight increase of current will occur as the servo attempts to hold position.

#2 Servo stalls under heavy load attempting to move to a commanded position but cannot get there. Stall current = MUCH larger than #1.

Flying around with flaps down....once the flaps reach commanded position, should be more #1.

Am I missing something? About 1 min of my flights is with flaps down to commanded position (#1).

Another key thing....the MiG flaps are small surfaces. Logically, the loads imposed on the flap servos cannot be very large compared to flap servo drive capability. If this were an issue, the AL37 with smaller servos and large flap area would be having issues. It isn’t.

-GG

This is how I always looked at current draw on a servo. Digital servos are slightly different because of their constant corrections but nothing like total stalled motor current....

[janmb]

Correct me if I am wrong... Servo holding current should be only a small % of stall current.

Follow me....

#1 Servo moves to commanded position and stops. If a load is applied, a slight increase of current will occur as the servo attempts to hold position.

#2 Servo stalls under heavy load attempting to move to a commanded position but cannot get there. Stall current = MUCH larger than #1.

Flying around with flaps down....once the flaps reach commanded position, should be more #1.

Am I missing something?

The difference in current draw between a servo working at/past its max capacity to reach a commanded position, vs the same servo struggling at/past its max capacity to remain where it is, is negligible. A servo like this we use in our models have no kind of brake to release the motor when stationary, so whether the servo struggles to move or struggles to stay makes no difference.

In both cases assuming the servo being pushed to its limit or more

[Airguardian]

40 flights a day... holy cow!

As far as "respect", by NOT giving recognition to a total stranger on the internet that I have no interaction with is disrespect?

That's not what I said. Don't twist my words.
The whole tone from your reply pretty was pretty much condescending and full of scorn towards the whole community of YT creators.

Re-quote for reference:

Not that I'm subscribing. I just don't get why some YouTubers are so desperate to get people to subscribe. They'll never get to the point where they'll make a living from it. Or do they really need people to "like" them?

And NO, I won't be subscribing to your channel either and that's NOT being disrespectful.

Never asked you for it. You are imagining things.

[1horse59]

Something im curious about is what kind of receivers everyone is using. I know in the world of spektrum, that their receivers are rated to output a certain amount of power. I have always used a ar9020 on my bigger foamies that use multiple power hungry servos and keeping the y connectors to a minimum and never had weird glitches. I might be wrong, but maybe some of these smaller 6ch recievers are not fully capable of supplying the full power the servos need to function properly leading to problems

Spektrum AR8010T.

[Evan D]

Orange 12ch and a Lemon diversity satellite...

[Skosh25]

Something im curious about is what kind of receivers everyone is using. I know in the world of spektrum, that their receivers are rated to output a certain amount of power. I have always used a ar9020 on my bigger foamies that use multiple power hungry servos and keeping the y connectors to a minimum and never had weird glitches. I might be wrong, but maybe some of these smaller 6ch recievers are not fully capable of supplying the full power the servos need to function properly leading to problems

Futaba R7008SB

[GliderGuy]

40 flights a day... holy cow!

Did this number of flights in a day only 3 times since March. Pretty weekend days at that.

-GG

[kallend]

Correct me if I am wrong... Servo holding current should be only a small % of stall current.

Follow me....

#1 Servo moves to commanded position and stops. If a load is applied, a slight increase of current will occur as the servo attempts to hold position.

#2 Servo stalls under heavy load attempting to move to a commanded position but cannot get there. Stall current = MUCH larger than #1.

Flying around with flaps down....once the flaps reach commanded position, should be more #1.

Am I missing something? About 1 min of my flights is with flaps down to commanded position (#1).

Another key thing....the MiG flaps are small surfaces. Logically, the loads imposed on the flap servos cannot be very large compared to flap servo drive capability. If this were an issue, the AL37 with smaller servos and large flap area would be having issues. It isn’t.

-GG

You're missing the point. The entire flight appears to have been "flaps down" including high speed passes. The flap servos may well have been (over)loaded continuously for several minutes. Do you know how they will behave under these conditions, which are not the same as your flights, nor the AL37 flown normally with flaps only extended at take-off and landing speeds.

[Gringotuerto]

I have been given to understand that every hole on the servo arm that you move out from the the first hole halves the rated torque for the servo.

That is incorrect. The torque is unchanged. The force it can provide reduces inversely as the distance of the hole from the servo output shaft.

Kallend is right. But I think the confusion comes in when people talk about the torque exerted on the control surface by the servo. The control rod is pushing the same force in both directions, on the servo arm and on the control horn. So if the rod is at distance DS at the servo end, and the servo has torque TS, then the force on the servo end of the rod is FS = TS/DS. Similarly the force on the rod at the other end, at the control horn, is FC=TC/DC (where DC is the distance from the hinge line to the hole on the control horn). Since it is one rod, obviously FC = FS. So that leads to TC = TS/DSxDC. So yes, when you move to a farther hole on the servo (increase DS) then the torque at the control surface (TC) goes down. But the servo rated torque TS doesn't change. The servo doesn't know if it is exerting a large force at a close distance or a small force at a large distance, because both feel the same to the motor. (That is, if servos had knowledge and feelings, lol).

Anyway, this is the basis of moving the rod to the closer hole on the Mig-29. The servo exerts the same torque regardless of where the rod is placed, but the elevator experiences higher applied torque (TC) when servo arm length is shorter (DS is reduced). You could equivalently move it farther out on the control horn (increase DC), since all that matters is the ratio of the distances (DC/DS). But since the recommended hole on the control horn is already at the end, there are no more holes available to do that.

[Skosh25]

So who is flying on the inner most hole?

[Airguardian]

Did this number of flights in a day only 3 times since March. Pretty weekend days at that.

Still hella impressive.
My typical flight session will be 4 to 6 flights.
10-14 on a full-day one (And that's with jets that take a single batt!)
40 on a day with a MiG that takes two 6S 5Ah bricks... me jealous!

[HaroldAnderson]

So who is flying on the inner most hole?

I have mine on the inner hole on the servo and get full factory recommended throws. FrSky RX8R Pro receiver with XM+ satellite. FrSky Taranis transmitter. Eagle A3 Super3 Gyro. 22 flights on the plane so far. I have never been able to detect any loss of elevator authority at the bottom of loops but I start reducing throttle at the top of the loop.

I drilled more holes on the horn of my FW F-18 to reduce the leverage at the elevator servo. To me it is crazy turning down throws excessively at the radio when changing the ratio is not that hard. The F-18 is the exception that mod was a pain and included modifying the pushrods to clear the servo spline.

[OV10]

Something im curious about is what kind of receivers everyone is using. I know in the world of spektrum, that their receivers are rated to output a certain amount of power. I have always used a ar9020 on my bigger foamies that use multiple power hungry servos and keeping the y connectors to a minimum and never had weird glitches. I might be wrong, but maybe some of these smaller 6ch recievers are not fully capable of supplying the full power the servos need to function properly leading to problems

The above statement in bold lettering is a misnomer. RC receivers do not generate a power output.
For a pilot to be anywhere near concerned about the receivers capability to "pass through" the power (amperage) as provided of an external source as required of the complete flight system you are basically looking at powering a giant scale model.
The circuit tracings in the smaller 6 channel Rx's are fully capable of handling the current/power demands of the models that are of predominant discussion of the threads throughout this forum.
The Spektrum receivers do have a minimum operating voltage of 3.5vdc. There is a Receiver Power System Requirements section in most Spektrum Rx manuals for which there is only voltage limits and no current requirements.
Here's an excerpt of these requirements taken from the AR8020T manual.

Receiver Power System Requirements
Inadequate power systems that are unable to provide the necessary minimum voltage to the receiver during flight have become the number one cause of in-flight failures. Some of the power system components that affect the ability to properly deliver adequate power include: • Receiver battery pack (number of cells, capacity, cell type, state of charge) • The ESC’s capability to deliver current to the receiver in electric aircraft • The switch harness, battery leads, servo leads, regulators etc. The AR8020T has a minimum operational voltage of 3.5 volts; it is highly recommended the power system be tested per the guidelines below. Recommended Power System Test Guidelines If a questionable power system is being used (e.g. small or old battery, ESC that may not have a BEC that will support high-current draw, etc.), it is recommended that a voltmeter be used to perform the following tests. View the receiver voltage during this test on your transmitters telemetry screen, load the control surfaces (apply pressure with your hand) while monitoring the voltage at the receiver. The voltage should remain above 4.8 volts even when all servos are heavily loaded. How QuickConnect™ Technology Works • When the receiver voltage drops below 3.5 volts, the system ceases to operate. • When power is restored, the receiver immediately attempts to reconnect. • If the transmitter was left on, the system reconnects typically in about 4/100 of a second. QuickConnect is designed to allow you to fly safely through most short duration power interruptions, however, the root cause of these interruptions must be corrected before the next flight to prevent a crash. NOTICE: If a brownout occurs in flight it is vital that the cause of the brownout be determined and corrected. IMPORTANT: When using Y-harness or servo extensions with Spektrum equipment, do not use reversing harnesses. Using reversing Y-harnesses or servo extensions may cause servos to operate erratically or not function at all.
The brand of receivers you use is really inconsequential until you venture into the world of the BIG BOYS(giant scale)

For what it is worth, I have been using Lemon and Admiral Rx's for years after dumping Spektrum due to unjustifiable high pricing.

Best regards,

[Evan D]

Me.


I move pushrods in on many set ups, on many surfaces, and increase the throw in the radio. Not only does this give more apparent force to the surface/ less strain on the servo, it also increases the apparent resolution. The down side is if there is slop it could make it worse.

So who is flying on the inner most hole?

[Reaper911]

Spektrum AR7350 mounted in nose with one satellite rx. 50% gain & 150% priority on AS3X