Official FlightLine RC 1600mm P-38 Lightning Thread

[Aros]

[GliderGuy]

Edit: It is suggested that you set the ESC brake to ON to minimize prop damage. (CAUTION…Remove the props when changing ESC settings for personal safety considerations). I got bit once by my P-38 props when it jumped out of its work-bench tie downs. Any trip to the ER is not fun!

Aros….good job!

If the nose gear ever fails to deploy, minimal damage will result with a gear down landing…no power to prevent prop damage.

Also I will chime in and confirm that I have not had cold-temp function issues. Mostly, wear-out issues. When my P-38 gets an intermittent gear servo problem that a re-bending of the strut won’t fix, I replace the servo ASAP….and fly gear down until it is replaced.

Typically a P-38 gear up landing on grass does more damage than a gear up landing on pavement. The grass and bumps tend to grab and stress items on the underside. A good gear up landing <zero power> on pavement is a non-event.

-GG

[xviper]

Twice, I had to do a gear up landing due to one of them not coming down, so I pulled them all up. I was lucky to have been able to belly land in tall grass, full flaps to slow it down and stalled it pancake style into the tall grass. I had the belly tanks on, so minimal scraping. Insofar as having the ESC brakes ON, that depends on your circumstances. On all my belly landing wings, I've better luck with the brake OFF. This allows the prop to be moved out of the way of the ground (be it flat or grass). When brakes are ON, there is always a chance that one blade will be stopped pointing directly at the ground when coming in and you find yourself blipping the throttle repeatedly to get the blade out of the way, often times never getting it right before the plane touches down, particularly with multis. I've broken a few props with brake ON but so far, never with brake OFF. Of course, the more blades a prop has, the more chance that a blade will be pointed straight down when the brake stops it.
HobbyKing Lancaster (had 2 of them), no gear, 4 x 4-blades props. With brake ON, snapped a couple props. Brakes OFF, they moved out of the way and no broken props. Each circumstance and plane will be different.

[GliderGuy]

Hi XViper,

With the ESCs on the P-38 set with brake on, the props on final slowly windmill …at least on my P-38 and the way the ESC brake-on setting behaves. On the ground….instant prop stop…no windmill slow down.

From my experience, if there is airstream flowing, the props slowly rotate and move out of the way upon ground contact. I broke props before I started setting the brake on. I’ve not broken any props since setting the brake on and also going to zero throttle just prior to touchdown.

Interesting difference in our experiences.

I’ve found that brake on also minimizes the prop damage which can result from a hard landing that compresses the struts enough to hit a prop.

If one has the option of pavement, a smooth, controlled, gear-up touchdown under full control is a non-event for a gear-up landing. Results in minimal scrape damage.

-GG

[xviper]

With the ESCs on the P-38 set with brake on, the props on final slowly windmill …at least on my P-38 and the way the ESC brake-on setting behaves. On the ground….instant prop stop…no windmill slow down.

You may have something here. On all my planes where I use brake ON (mainly sailplanes with folding props), brake force is at max so that the prop stops immediately regardless of airspeed. I've tried it with a medium brake and with airspeed, the folding prop still stays open and windmills slowly as in your case. Same for fixed props. I've only ever used either no brake or brake force at max.
Although a different scenario, on my EDFs with reverse thrust, brake force must be at max so the fan stops ASAP before going into reverse.
As an anecdote from my past life as a firefighter, I responded to a twin engine aircraft (low wing), gear stuck in the up position. He cut the engines for a belly landing. As we waited beside the end of the runway, we noticed that one prop was stopped perpendicular to the ground. We were all thinking, "This guy's going to nail the ground and flip over when the prop hit". Nearing the end of the runway, we could see the pilot cranking that one engine to get the prop parallel to the ground and just 50' off the deck, he did it and did a perfect belly land on the ground beside the runway. Everyone climbed out of the plane with smiles on their faces. Some of that memory stayed with me when I started flying RC.

[GliderGuy]

Out of curiosity, I pulled out the ESC programming manual that came with the P-38. There is only an ON or OFF setting. No MAX/HARD or SOFT options.

ON = slowly windmilling with airflow but instant stop while sitting on the ground

OFF = fast windmilling with airflow and several seconds of wind-down windmilling after chopping the throttle while on the ground.

https://www.freewing-model.com/downl...esc-manual.pdf

That pilot was on the ball.

-GG

[xviper]

I see that now about the ESC brake being ON or OFF. I can only imagine that on planes that swing large diameter props, that a "hard" brake setting would be detrimental to the motor magnets. In the same token, I would not expect throttle would be a "hard" start, either.

[GliderGuy]

LOL - Regardless, even the ESC brake’s “soft ON” causes the prop nut to become loose after some number of cycles. Therefore, an application of Foam-Tac on the prop nut’s threads is suggested.

Note: Not LockTight, unless it is the plastic safe type. Regular LockTight will eat the spinner and hub plastic.

-GG

[xviper]

ALL threaded fasteners and "C/E" clips and hex screws get a bit of FoamTac on my planes.

[redbarn]

Hello there Everybody,
Has anyone tried out the Benchcraft hollow rubber wheels on the P-38? 2-3/4" nose and 3" mains? If not, what seems to be everyone's favorites? I'm going to install the suspension struts and I'd like to use a good softer tire with them. Maybe nothing else works on those struts?

[xviper]

Hello there Everybody,
Has anyone tried out the Benchcraft hollow rubber wheels on the P-38? 2-3/4" nose and 3" mains? If not, what seems to be everyone's favorites? I'm going to install the suspension struts and I'd like to use a good softer tire with them. Maybe nothing else works on those struts?

What works on those struts is dependent upon the tire width and axle hole diameter. As for the wheel diameter .............................
If you've been reading the posts from the previous page, you'll see that the stock gear can sometimes get stuck in the wheel well due to the tire touching the top of the wheel compartment and not allowing the retract to complete its full closing cycle. Those tires you plan to use are larger than the stock tires and would likely hit the top of the wheel well even easier. However, the key point would be the total length of the strut and tire assembly and how close to the top of the wheel well they come.

[redbarn]

Thank you for the response XV. Maybe I'll just try the stock wheels on the suspension struts for now. My runway is packed sand with some weeds here and there that I keep whacked down really short but there are a few bumps that the plane would benefit from having a little give in the gear. I have the Tigercat with the stock wheels and struts and it does ok. You just can't leave it sitting on the wheels a long time or they'll flat spot pretty bad. That's another reason that I was thinking of trying different wheels like the Robarts. The softer tires don't dig into the occasional softer sandy spots as bad either. Maybe 2- 3/4" Robarts on main stock struts? Be less parts to get loose and worn. Guess there's never a perfect setup except maybe the Bronco. It's gear works pretty good on my terrain.

[GliderGuy]

Hi Redbarn,
The stock wheels are soft and will flat spot after a time of sitting. However, the “sold by itself” replacement wheels are (at least the last ones I bought) a stiffer material and don’t flat spot as bad.

-GG

[redbarn]

GG,
Are those the wheels that come on the suspension struts?

[GliderGuy]

GG,
Are those the wheels that come on the suspension struts?

The tires with the upgrade strut set will flatspot. When I ordered some stand-alone wheels (no struts)….they are a different tire material less prone to flat spotting.

-GG

[redbarn]

Went with the stock sized Robarts and the suspension struts. Had to do some customizing on the axles and what not, but they worked okay. I also changed out the esc's with a pair that I can reverse the thrust with. I think I'll appreciate the ability to stop this plane. Wiring this plane is a fun challenge. Here's some pictures of how I approached it. The battery leads are also connected together with an XT 60 connector that I soldered between the leads.

[xviper]

I also changed out the esc's with a pair that I can reverse the thrust with.

What brand and size of reversing ESCs did you use?

[redbarn]

Xviper,
The ECS's are Avian 70 amps. The ones that are used in the eflite 1300mm T-28. It was nice to be able to forward program them. I did them individually before final install. They put out 6v on the BEC and that part isn't adjustable. Didn't realize that when I decided to use these but hopefully my retracts and servos are ok with that. Another thing that happens when you connect two of these esc's together is that the telemetry goes away. I'm not concerned with that really but it would be nice to see some of the info initially anyway. If I had it to do over again I'd probably just use the Hobbywing Platinum Pro V4's. They are a good esc, I have a programmer, the BEC is adjustable and they have reversing brake. Ten bucks cheaper too! I don't know if you ran only one Avian with another esc combined if the telemetry would work or not. It would be interesting to see if two different esc's would run the same rpm. Kinda important on a twin engine airplane. The Avian's seem to sinc pretty well together.

[xviper]

redbarn, I have used the Avian ESCs in my PJ50 and the HobbyWing reversing ESCs in my AL-37. I was curious as to how you made the Avians work for twin reverse using a single receiver. I had a heck of a time making it happen. I would program reverse for each Avian individually, however, when I Y'd the 2 throttle leads together and tried reverse, only one motor reversed. The RX would not talk to the other ESC to tell it to go into reverse. It seems that it would not convey 2 reverse signals through a single throttle port, then into 2 leads via a Y. Only by using a separate, smaller, 4-ch smart RX for the second ESC, could I make both work. The 4-ch RX only had the one throttle lead plugged into it. The primary RX did everything else. (Note: The very first time I hooked it all up with just 1 RX, twin reverse worked. HOWEVER, all subsequent attempts failed. That's when I went with the 2nd RX. I'm still baffled to this day why it happened that way.)
In my AL-37, when using twin HobbyWings, because each ESC had its own reverse lead, I could Y them together into a separate channel and both motors reversed without issue. This is the way I'll do any future dual motor reversing.

[redbarn]

There may be coming issues for me here but so far it's working ok. It does initially on power up run a motor in reverse for some reason, but if I flip the reverse switch and throttle it up a little bit and then switch back to forward the motors run properly. I haven't seen any issues with wrong rotations after the initial power up. I will certainly be testing this more rigorously now before any flights. I have enough channels to run each motor on it's own channel. Maybe that would work better? Probably won't cure the telemetry thing though. Anyway, It's working ok enough at the moment...Knock on wood