Official FlightLine 1600mm B-25J Mitchell PNP Thread

[Elbee]

I haven't done any mod to my B25 gear. The results are based on FnL's testing. What it sounds like 3.5" is gonna be a little tight for the main. NG will be fine with 2.25"

I've been using Robart tires on many of my scale models. Have yet to notice the "ballooning" at landing speed RPMs.

EK, thanks, I haven't either and like you, I have used Robart's tires wherever I can for years.

My presumption is Fast N Light might still be tweaking his 3DP wheel set.

I know I had to do some sizing changes when I used my own wheel designs for the Robart Tires on my FL 1600mm Corsair.

Best, LB

[Enzo_K]

Enzo_K Fast N Light ,

So just for clarity, both Robart 3.25 and 3.5 are good-to-go for the MGs, and Robart 2.25 for the NG.

Have either of you noticed the Robarts 'ballooning' some at landing speed RPMs and interfering with the struts?

Best, LB

I haven't done any mod to my B25 gear. The results are based on Fast N Light's testing. What it sounds like 3.5" is gonna be a little tight for the main. NG will be fine with 2.25"

I've been using Robart tires on many of my scale models. Have yet to notice the "ballooning" at landing speed RPMs.

[LucB]

Anyone have the ESC calibration instructions? I didn't see anything on the Motion site. My 1st twin engine plane so I want to minimize the chances of messing up the beep, beep, beep...

Did the basics: Tx on, 100% full throttle, motor on switch. Connect battery to ESC, beep beep, move throttle to 0%. Heard beep beep beep beep beep beep. Seems to be working OK.

I got this link from MRC.eu: https://www.hobbywing.com/en/uploads...7152905f10.pdf
It is for the ESC with UBEC but it should be the same for the other one.

[Elbee]

Enzo_K Fast N Light ,

So just for clarity, both Robart 3.25 and 3.5 are good-to-go for the MGs, and Robart 2.25 for the NG.

Have either of you noticed the Robarts 'ballooning' some at landing speed RPMs and interfering with the struts?

Best, LB

[Fast N Light]

Really appreciate the effort.

Some experience sharing. Robart wheels are also a bit thicker than the stock wheels. But if you make the rim thinner. When you squish the rubber tires, they "zoom-out" some. So I think the 2.25" will probably be a better choice for the nose. Same goes for the mains.

Best of luck with the mod. Looking forward to getting this mod for mine.

Yes the 2.25" is the better option for the nose to prevent radial interference with the strut. Motion shipping those Robarts my way at the moment.

A bit of tuning the main rim design and the 3.5" looks good to me. The clearance might be too tight if your going to get mud on the tires, but I won't be doing that. 3.25" should also work fine and no one will notice the difference unless your parked next to me. lol

The tire to rim interface I am using is similar to the Robart rim which only provides lateral tire support at the center-line. Currently testing thinner gap geometry there to see what effect it has.

[Enzo_K]

Evan, I had a cerebral flatulence not to mention I was in the Army and not the navy and had my fore and aft confused. I think I was task loading today. RR. I was thinking the same thing. I would rather have it balanced while in flight and use a little elevator when landing. It balances perfectly with the battery all the way forward and wheels up. I will try it with moving the battery back and see what it does to the the CG with the wheels up and wheels down.

Had mine balanced on CG mark with the wheel down. And it flies great. I did not notice any tail-heavy tendency after the wheels were up during the flight. It does not have a ton of elevator authority. So balancing it nose-heavy with the wheel down may not be a good idea.

[themudduck]

Evan, thank you. I am sorry I failed to mention I have the battery as far forward as I can get it. I use a Great Planes CG Machine to check the CG on my planes. Maybe I will just use my fingers and see it it comes out right.

What battery (mah size) are you using and how much does it weigh?

[desertdrifter7]

Evan, I had a cerebral flatulence not to mention I was in the Army and not the navy and had my fore and aft confused. I think I was task loading today. RR. I was thinking the same thing. I would rather have it balanced while in flight and use a little elevator when landing. It balances perfectly with the battery all the way forward and wheels up. I will try it with moving the battery back and see what it does to the the CG with the wheels up and wheels down.

[desertdrifter7]

Evan, thank you. I am sorry I failed to mention I have the battery as far forward as I can get it. I use a Great Planes CG Machine to check the CG on my planes. Maybe I will just use my fingers and see it it comes out right.

[RRHandy]

The B-25 is like flying the Corsair, Balance with the gear up for flight because the gear swing behind the CG and a nose heavy plane will fly again. Evan is right. My .02

R.

[Evan D]

Mine flies well balanced at the marks gear down.

But for the sake of discussion if you have the battery all the way forward why add tail weight instead of moving the battery aft?

[desertdrifter7]

With a spectrum smart battery 5000mAh all the way forward and the plane upright, since it is a mid-wing (not low or high), I opted to balance it upright. With the gear up it balanced perfectly but with it down it was very nose heavy. To balance it with gear down will require tail weight and I am very reluctant to do that. I would appreciate any input.

[MikeT]

A friend received his B-25 and brought it by the shop for help with programing the radio. I was really impressed by it.

Mike

[borntoolate]

The B-25 spare parts are now in inventory!!!

[Enzo_K]

Also a heads up for everybody. If your prop nut comes with a metal "bar" thing inside the thread. Reach out to MRC and get a replacement. This bar thing is not supposed to be there. Forcibly screwing on the prop nut will damage your motor shaft.

I talked to Freewing about this. They found 2 of these defective prop nuts in a batch of 200 of them. That doesn't mean there are only 2 of them in the batch we are receiving now in the US. Coz I happened to receive two defects. One of the bar was not in the way of screwing on to the motor shaft. But the other one destroyed some of the threads on one of my motor shafts. Luckily I was able to clean it off with some threading tool. And there was enough thread left for the nut to lock on to.

[Enzo_K]

Got started on my build and have the following updates on the scale rims. Thingiverse

The OEM nose gear wheel measures 2.4inch and has very little radial clearance to the support strut. The Robart 2.5inch wheel measures ~2.64inch which results in interference with the support strut. I will evaluate the Robart 2.25inch wheel as a possible mitigation for this issue. Hope it fits without modification to the rim.

Metal finish on the nose gear strut look pretty bad. Hope the metal structural integrity isn't compromised.

The OEM main tires measure 3.33inch and the Robart 3.5inch measure ~3.53inch. The increased diameter can cause interference between the outboard gear door and the Robart tire. Moving the wheel inboard can address this issue. Removing the OEM 1.75mm aluminum spacer will create space for the outboard gear door to close. A ~1mm washer may replace the spacer with minor adjustment of the outer gear door push rod.

The 3.5inch looks great but the fit to the gear door remains a close fit. I don't think the tires touch the doors on my setup. However, if you prefer more clearance, Robart 3.25inch should fit on the printed rims also.

PS - Thanks JD for the feedback!

Really appreciate the effort.

Some experience sharing. Robart wheels are also a bit thicker than the stock wheels. But if you make the rim thinner. When you squish the rubber tires, they "zoom-out" some. So I think the 2.25" will probably be a better choice for the nose. Same goes for the mains.

Best of luck with the mod. Looking forward to getting this mod for mine.

[Enzo_K]

Mike, Welcome to Hobby Squawk, Sir.

If you are able, post a few pictures of your issue.

Uncertain about the heat explanation, as the whole box would have to 'heat soak' down to the paint finish.

With all that 'foam and cardboard' inbetween, the airframe is well insulated.

If there is a real issue, document it!

Motion RC has great Customer Service.

Best, LB

Have the same issue on MANY Freewing/Flightline products. Dating back as early as late 2021 (Been a Freewing customer for years, early 2022 or late 2021 was the first time I encountered this issue)

I have a whole story to share if somebody is interested. I will cut it short here: MRC CS is a joke. I don't wanna mention names. But if you are talking with someone's name starts with a D & an M. You are better off just rubbing it in.

This "Gatoring" issue has been going on for almost 2 years. And no one at MRC ever wanted to address it.

I am currently arguing with MRC about my B25. Screenshots from Arthur RC's video show how bad some of the "gatoring" is. Some of them are minor. Like my Ta152 and Mirage. You could probably deal with it. Some of them are just unbearable. Like my P38, B25 & A6.

My speculation on this is the "Gatoring" happened during sea transfers. Which I think MRC is in charge of, correct me if I'm wrong. Because none of the social media in mainland China have I ever heard about this "Gatoring" issue complain. Nor has any of my friends in China ever experienced this "Gatoring" issue from Freewing/ Flightline products. At least not on a large scale (small imperfections are acceptable, but this is way beyond).
Edited 1: I don't think it is caused by sitting at the US customs for inspections. As Arthur RC is located in France, and received his B25 in early August. Also, it doesn't explain past "Gatoring" on other models.

Here are some examples of the A6 and the B25. Open attachments to see more life-like gators! Lol


BTW, the maiden flight of my B25. And my review:

Decent flying characteristics. 15m + flight time on 6000mah 6S pack.

Goes together nicely, took me about 15m to assemble.

The details are decent in general.

Pros: Great landing gear details. Rotatable top turret (used a 360 servo to operate it). Functional bomb bay (a little bit too shallow to fit anything).

Cons: Did not come with a pitot tube on the starboard side wing (Added one myself using a coffee straw).
Added a few antenna details along the rear part of the fuselage.
A lot of the panel lines are missing. The flaps, elevators & rudders are completely blank. A few panel lines are also missing from the wing top & bottom, as well as along the fuselage. Ended up adding them myself.

https://www.youtube.com/watch?v=ha95x_uqLn4

[rlcamden]

Received my B-25 last week. Had it together in about an hour. My club had our fall fly-in the past Saturday. It was a little cold and windy, but non the less, the plane handled it perfectly. The design and flight characteristics are excellent. Keep it up Flightline.

[Fast N Light]

Anyone have the ESC calibration instructions? I didn't see anything on the Motion site. My 1st twin engine plane so I want to minimize the chances of messing up the beep, beep, beep...

Did the basics: Tx on, 100% full throttle, motor on switch. Connect battery to ESC, beep beep, move throttle to 0%. Heard beep beep beep beep beep beep. Seems to be working OK.

[Fast N Light]

Got started on my build and have the following updates on the scale rims. Thingiverse

The OEM nose gear wheel measures 2.4inch and has very little radial clearance to the support strut. The Robart 2.5inch wheel measures ~2.64inch which results in interference with the support strut. I will evaluate the Robart 2.25inch wheel as a possible mitigation for this issue. Hope it fits without modification to the rim.

Metal finish on the nose gear strut look pretty bad. Hope the metal structural integrity isn't compromised.

The OEM main tires measure 3.33inch and the Robart 3.5inch measure ~3.53inch. The increased diameter can cause interference between the outboard gear door and the Robart tire. Moving the wheel inboard can address this issue. Removing the OEM 1.75mm aluminum spacer will create space for the outboard gear door to close. A ~1mm washer may replace the spacer with minor adjustment of the outer gear door push rod.

The 3.5inch looks great but the fit to the gear door remains a close fit. I don't think the tires touch the doors on my setup. However, if you prefer more clearance, Robart 3.25inch should fit on the printed rims also.

PS - Thanks JD for the feedback!