Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[crxmanpat]

And yes....RC pilots can be clueless about flaps.

And some full scale pilots as well. Just ask the KC-135 crew that was taken off flight status for over speeding the flaps.

[RudyD54]

Thanks for all the feedback. I'll talk to Freewing. I'm thinking of doing three kits:
1) Full kit
2) Metal control horns, push rods, and metal clevis only (hardware pack)
3) servos only (likely less demand for this one but always good to have extra servos on hand)

If there is any other feedback, please let me know. keep it coming. I appreciate it!

I saw some questions about the slow deployment of flaps. This is general and applies to all planes. From my recollection, it was about amp draw. We had a small set of customers who slowed their flap deployment down to around 7-10 seconds. When the flaps were deployed that slowly, they drew more amperage. Since the flaps were going down so slowly, usually at some point during the flaps deployment process, the gear was put down and this often happened while in a turn. With all these things going on at once and extra amperage going to the flaps, we saw a couple cases where the BEC was overwhelmed. That was how the recommendation for flaps came about. 2-3 second deployment is not an issue. 5+ can become an issue.

That kit breakout sounds good and thanks for the explanation. 7-10 seconds is an awfully long amount of time to spend deploying flaps and I could see how that could cause excessive draw while deploying gear. With 2 seconds my flaps are fully deployed by the time I reach for the gear switch which is probably why I haven’t had any issues.

[GliderGuy]

And some full scale pilots as well. Just ask the KC-135 crew that was taken off flight status for over speeding the flaps.

Side story —— My dad’s B-25 instructor (WW2) got the impression that my dad was afraid of the bird. The instructor said, “Let me show you how tough this bird is!” Then went into a full power dive to the deck and immediately dropped full flaps at this high speed and zoomed back to altitude.

The next day this instructor and a different student were killed in this same B-25....on final approach, a flap departed and she rolled in.

-GG

[radfordc]

This is true. However, I think that's where some people have a problem. They don't understand airspeed management and how it relates to flap deployment.

I will meekly take my internet thrashing for mis-managing the flaps on my Mig-29. As a licensed pilot I'm very aware of flap speed limitations and was also aware of the Mig's "interesting" reactions to flap deployment at speed. I my defense I will say that the Mig-29 is the only plane that I've crashed due to a momentary lapse of judgement in the use of the flaps. I'm talking about over 150 different planes over the last 60 years. I wonder if the latest manual has any sort of warning about this. They seem to offer warning for everything else (don't fly in thunderstorms for example).

[radfordc]

With 2 seconds my flaps are fully deployed by the time I reach for the gear switch which is probably why I haven’t had any issues.

Interesting that you do it that way. Full scale pilots always (nearly always?) deploy the landing gear first before the flaps. Gear extension speed is usually much higher than flap speed limits and lowering the gear gets the plane slowed down to flap speed quickly.

[kallend]

. . . . Gear extension speed is usually much higher than flap speed limits and lowering the gear gets the plane slowed down to flap speed quickly.

Not on my Mooney.

[RudyD54]

Interesting that you do it that way. Full scale pilots always (nearly always?) deploy the landing gear first before the flaps. Gear extension speed is usually much higher than flap speed limits and lowering the gear gets the plane slowed down to flap speed quickly.

Oh man I’ve never really thought about the order of it but what you’re saying makes total sense. I always deploy flaps once I’ve slowed down but of course the drag of the gear would help me get slower faster.

I can’t speak for full scale though as I’ve never flown one. I’m just a dude with some toys…

[xviper]

I will meekly take my internet thrashing for mis-managing the flaps on my Mig-29. As a licensed pilot I'm very aware of flap speed limitations and was also aware of the Mig's "interesting" reactions to flap deployment at speed. I my defense I will say that the Mig-29 is the only plane that I've crashed due to a momentary lapse of judgement in the use of the flaps. I'm talking about over 150 different planes over the last 60 years. I wonder if the latest manual has any sort of warning about this. They seem to offer warning for everything else (don't fly in thunderstorms for example).

You should not be embarrassed about this. We all still do stuff like this from time to time. I found a statement that holds true ..................... "If you ain't crashing, you ain't having any fun." With that in mind, I crash every now and then just to show people I'm still having fun.

Interesting that you do it that way. Full scale pilots always (nearly always?) deploy the landing gear first before the flaps. Gear extension speed is usually much higher than flap speed limits and lowering the gear gets the plane slowed down to flap speed quickly.

I've started doing just this of late. Wheels down first, then 1/2 flaps, then full flaps as speed decreases. On many of my planes, I won't use full flaps at all until the wheels touch the ground. Full flaps to help reduce the roll distance.

[Evan D]

I have flaps on a slider but this is what I've always done. I like flaps on a slider because I can feed in a little more or less depending on how the plane is handling things like wind, rotor over the trees at the end of our runway, etc... Usually full to slow down and I have crow and rudder air brakes on quite a few planes.

I've started doing just this of late. Wheels down first, then 1/2 flaps, then full flaps as speed decreases. On many of my planes, I won't use full flaps at all until the wheels touch the ground. Full flaps to help reduce the roll distance.

[crxmanpat]

Interesting that you do it that way. Full scale pilots always (nearly always?) deploy the landing gear first before the flaps. Gear extension speed is usually much higher than flap speed limits and lowering the gear gets the plane slowed down to flap speed quickly.

Every airline I've ever been on extends flaps WELL before lowering gear. Gear usually doesn't come down until about 5 miles on short final. Flaps usually start coming down 50 miles out. Not full of course, but flaps are out long before gear.

As far as my models, since I've started flying turbines I've gotten into the habit of doing a gear pass at half throttle, turn at mid field for the downwind, then start slowing down more and extending flaps. I do this for everything I fly now, turbines and EDF.

[fredmdbud]

Every airline I've ever been on extends flaps WELL before lowering gear. Gear usually doesn't come down until about 5 miles on short final. Flaps usually start coming down 50 miles out. Not full of course, but flaps are out long before gear.

As far as my models, since I've started flying turbines I've gotten into the habit of doing a gear pass at half throttle, turn at mid field for the downwind, then start slowing down more and extending flaps. I do this for everything I fly now, turbines and EDF.

The F/A-18 procedures deploy both:

7.3.2 Approach. See figure 7-2. Enter the pattern as prescribed by local course rules. At the break, reduce thrust and extend the speedbrake (if required). As the airspeed decreases through 250 knots, lower the landing gear and place the FLAP switch to FULL and ensure that speedbrake is retracted. Retract speedbrake, if extended. Decelerate to on-speed, and compare airspeed and angle of attack. Complete the landing checklist. Roll into the base leg and establish a rate of descent, maintaining on-speed AOA. On-speed without external stores and 2,000 pounds of internal fuel is about 125 knots. Add about 2.5 knots for each 1,000 pounds increase in fuel and stores. Rate of descent can be established using the velocity vector on the HUD to set the glide-slope. Avoid overcontrolling the throttles as thrust response is immediate. Compensate for crosswind by crabbing the aircraft into the wind on final approach.

- NATOPS FLIGHT MANUAL

Same for the MiG-29.

Could be because of different flight characteristics due to role - cargo transports probably follow similar procedures as airliners,

[Airguardian]

Thanks for all the feedback. I'll talk to Freewing. I'm thinking of doing three kits:
1) Full kit
2) Metal control horns, push rods, and metal clevis only (hardware pack)
3) servos only (likely less demand for this one but always good to have extra servos on hand)

If there is any other feedback, please let me know. keep it coming. I appreciate it!

Sounds reasonable... I like options!
I would like to know the servo specs though: Voltage range, speed, torque, gear material, and refresh-rate capability.
I may want to upgrade my stab servos but I'd rather invest in fast, 100-300Hz capable servos so that I can take full advantage of gyro-stabilization the day I decide to install a good gyro on my jet.

And since we are at it with feedback, I'd definitely also buy the pushrods as a separate upgrade for other full-flying-stab jets if they were available in the correct length (I am thinking of the Su-35 in particular). :)

Lastly: I would have loved to see Motion/Freewing go the extra mile and rethink the whole stab assembly and implement the scale axis and beefen up the stab assembly to better deal with torsional loads. Even with the beefiest servos and linkages I still think the whole assembly is a bit weak and prone to deformation under load. Even if not fatal once the rest of issues are adressed it's certainly not ideal.

Oh, and the thrustline of the MiG-29 and F-18 are way off. MiG-29 pushes nose up, F-18 ditches nose down. neither is good, and these are rather difficult fixes for end users that could more easily get sorted out at factory. F-18 in particular looks like the plastic nozzles are often not glued well-aligned with the foam, so a wedge appears on the bottom causing the airflow to deflect down. I think it would likely be possible to fix that without need for any change of molds or expensive stuff, just additional training of the personnel responsible for the intsallation of those nozzles.

Hope that helps!

Good question. To break those arms requires a lot of stress, and the only reason there's a lot of stress there is the aerodynamic design of the airframe.

I must concur.
Of course, this really manifests when people make the mistake of deploying flaps at too high speeds, particularly if they are running nose-heavy setups.
But both facts are not mutually exclusive.

There has been a lot of discussion in Avanti threads about flap servos not responding well to slow speed of operation.

It was a concern with the F-18 too (which is how the question came about in Alpha's stream originally).

I’ve got flap deployment set to 2 seconds on all of my planes and have not come across any issues yet. Is this something that’s come up immediately or after some time?

So do I, and neither have I had any problem so far, but apparently it is a thing.
Read plenty of reports of people having a flap servo get stuck when hitting the deploy switch, and it seems most if not all had delay functions active.
Personally, I'd rather keep the delay and just be careful to switch flaps back up if jet starts rolling as you hit it.
Or replace by beefier servos.

I saw some questions about the slow deployment of flaps. This is general and applies to all planes. From my recollection, it was about amp draw. We had a small set of customers who slowed their flap deployment down to around 7-10 seconds. When the flaps were deployed that slowly, they drew more amperage. Since the flaps were going down so slowly, usually at some point during the flaps deployment process, the gear was put down and this often happened while in a turn. With all these things going on at once and extra amperage going to the flaps, we saw a couple cases where the BEC was overwhelmed. That was how the recommendation for flaps came about. 2-3 second deployment is not an issue. 5+ can become an issue.

Thanks for this bit of info, glad to see the issue was further researched!

[fredmdbud]

The thrust-line alignment changes when the CofG (CofM) changes - a caveat to the aft-CG folks.

[Airguardian]

Regarding flaps, we should be differentiating landing flaps from other flap usage.

Planes like the Hornet actively deploy flaps AT SPEED to help improve and optimize the flight envelope.
Of course, these are not full-flap deflections but they still cause the stabs to see an increased aerodynamic load.
To suggest flap deployment at speed is stupid is short sighted at best. It totally depends on each design and particular use.
Of course, full flap deflection when going ballistic is silly but things are not only black and white, you know...
There are many scenarios where flap usage at speed is perfectly warranted and accounted for in the design of the birds, be them fullscale or model aircraft.

I wonder if the latest manual has any sort of warning about this. They seem to offer warning for everything else (don't fly in thunderstorms for example).

Hey, I like flying in thunderstorms!

The thrust-line alignment changes when the CofG (CofM) changes - a caveat to the aft-CG folks.

BS, thrustline should NOT be made/designed to compensate for CG changes (fore/aft).
There are more intelligent ways of dealing with that.

[themudduck]

Since there is already loads of speculation, I'll address the Mig-29 upgrade servos.

Thank you very much SuperTom for joining this discussion and supplying us with the news. I would like to see an upgrade kit with all the parts (2 servos, rods, metal arm, etc) offered on the website and personally I would like to purchase the metal servo arms..

Like many others I received the upgrade elevator servos from MRC when this problem got started, changed the pushrods to 4-40 with HD ball links, strengthened the elevator horn mounts, and I am using the inner hole on the plastic servo arm.

Question for you: is the "30gm servo" (which is currently on backorder) the same servo as MRC sent out to us last year? Someone mentioned a 27gm servo but there is no such beast on the MRC servo page. Should I get the 30gm servo? If its more powerful than the earlier servo then I would like that extra bit of insurance. If its the same then I only need the metal arm. But will the metal arm fit the servo that you sent me last year?

[Tom]

Question for you: is the "30gm servo" (which is currently on backorder) the same servo as MRC sent out to us last year? Someone mentioned a 27gm servo but there is no such beast on the MRC servo page. Should I get the 30gm servo? If its more powerful than the earlier servo then I would like that extra bit of insurance. If its the same then I only need the metal arm. But will the metal arm fit the servo that you sent me last year?

The earlier servo is a 23 gram servo. This servo is the same size but with different internals making it heavier. I suspect the spline is the same as the 23g servo but I've asked Freewing to be 100% sure. If the spline is the same, there is no reason the new metal servo arm will not work on the 23g servo. I'll post more when I know for sure. I will also post the full specs of the 30g servo when I know them for sure. I know the trial specs but I don't want to assume they are the exact same so I'll post more when I know more as soon as I know. These new servos are higher torque for sure. The higher torque was added to cope with the turbulence a high speed flap deployment causes. If you don't deploy flaps at 85%+ throttle, I would not worry. If you want an insurance policy, we will have the servos and full upgrade kits available. I'm asking Freewing for a part number and pricing tonight.

[Airguardian]

Thank you!

[fredmdbud]

BS, thrustline should NOT be made/designed to compensate for CG changes (fore/aft).
There are more intelligent ways of dealing with that.

I'm talking about a matter of fact as-is, not redesign. Would an aerodynamic fix work in post-stall when the surfaces aren't effective?

Maybe an intelligent way of dealing with the pitch-up it is offering 3D STLs with a variety of angles to suit different CGs? Hmmmmm.

Or just buy the TV units and set the TV pitch trim for the desired angle at neutral.

There, no redesign necessary.

Here's an idea - why not set your plane on a plane balance stand at one CG point, and see how much pitch induced at a certain throttle setting. Then change CG, rebalance on the stand, and see if there's a difference in pitch at the same throttle setting?

Then do the same with another plane, like the F/A-18, where the thrustline aligns with the centerline of the fuselage?

[4qr1hu9n7]

If you're a veterans r.c. modeler. All these changes are obvious.

[Shaun Evans]

Wow,

I guess you learn something new every day (if you allow yourself to)! Slow flap deployment as a cause for failure/crashes/bad juju? That's definitely a new one on me! Frankly, I'm having a hard time reconciling that. In my simpleton mind, it seems something else is the root issue if slowing flap deployment does something bad. Side-note, has anyone had or reported issues with missed approaches (full throttle with full flaps already deployed)? I think the fact that my engine has a spool-up delay will probably help a bit since my airframe doesn't see instant strain from the thrust.

Do I understand that the new kits include 30gr servos and all these hardware upgrades? Am I reading that right?