Scale Build-Off- ParkflyerPlastics 95" span P-40

willsonman

Builder Extraordinare
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Personally, I like the green nose. Wonderful to see you making such great progress to bring her back to her full, intended, livery. I MAY have you beat on a few gimmicks in my Corsair but TBH I love yours more. Ever since I first saw her at FF I wanted to do gimmicks like that in an aircraft so I'll give you inspirational credit for me doing so in the Corsair. This is such a fantastic project and REALLY showcases how wonderful foam is to work with.
 

wilmracer

I build things that fly (sometimes)
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Thanks man! That Corsair is amazing and I'm really hoping I can get that level of detail on my next build. VERY inspiring.

Still grinding along. Spinner painted, Prop and spinner balanced, and mounted back up. I stayed with the green. Maybe I wasn't feeling adventurous. The red just felt a little flashy and I want this one to feel a bit more war-weary. I also thought the red would draw your eyes more to the spinner and then you would notice the large gap on the left side necessary for me to get the thrust angle right. Maybe I'll be able to take some of the down/right out after flying her with the lighter 2 blade, but we'll see.

Cockpit side panels were installed and the pilot was put back in his office. The seat is secured to a solid plate and he is secured to the seat with velcro, double sided tape, and the functional lap belt (which is secured with CA to the seat). I got the right hand and stick put back in and secured the stick with a big glob of silicone adhesive. This will hopefully keep it secured without shaking loose.

Does anyone have suggestions for cleaning up fine scratches on canopies? I seem to remember hearing Future Finish floor polish works but I've never tried it. I figure while I have the canopy off I should get it as clean as possible so you can see the pilot.
 

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willsonman

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Well, as odd as it may seem, I would mask off the frame of the canopy with tape. Then go by some automotive clear coat and spray that on. It is UV resistant and usually comes in high-gloss and it is generally more scratch-resistant than the bare PETG plastic.
 

wilmracer

I build things that fly (sometimes)
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Well, as odd as it may seem, I would mask off the frame of the canopy with tape. Then go by some automotive clear coat and spray that on. It is UV resistant and usually comes in high-gloss and it is generally more scratch-resistant than the bare PETG plastic.

Interesting. I'll have to pick some up and give that a shot. In general I haven't worried about scratches in the past but I figure I'd like to see inside this one.
 

willsonman

Builder Extraordinare
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You have time so you could find a piece of scrap plastic to try first and then have a go at the canopy.
 

wilmracer

I build things that fly (sometimes)
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All buttoned up and waiting for FF! Heading out of town for a week now but I'll probably try to get a shakedown flight or two on the new prop and wheels before FF, but she's ready for Ohio! Lurking in the background are a few other long overdue projects that need attention. I'll be getting to them soon ;-)
 

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wilmracer

I build things that fly (sometimes)
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So it has been a year and a lot had happened with this project. First, she made her appearance at FFOH 2018. I had hoped she might be worth her own feature or episode, and when Stephan walked over with the film crew I thought that might be in the cards. BUT... That runway was SO tight. There was a combination of two things going on.

1: The fabric runway bunched up in front of the wheels, adding drag and making her want to nose over, and

2: The runway was just SO narrow. Like all warbirds she wants to pull to the left and you have to counter with right rudder. She ALSO requires a lot of right aileron so that the P-factor doesn't just lift the right wing right into a stall (See early flight attempts). What I really would have had to do was basically point her at the crowd that was lining the runway and HOPE no one got hit. I think I was subconsciously light on the right input so into the soybeans she went. Twice.


Damage was minimal though. A new prop and spinner and she was ready for action. Or so I thought.

I had her back out at a Warbird event at a local club a few months later and we discovered the retracts were now acting up. Basically they would unscrew themselves when pulling the gear up and then would fail. FORTUNATELY it never happened on in the air. So she was grounded for that event.

I contacted Robart and a new set of actuators was sent. These also failed during testing and she continued to be grounded. A third set was sent and installed. A few of us got together over the winter to do some flying and I was so sure she was ready to go. I don't remember if it was Joshua or Pat who recommended I cycle them one more time for good measure, but damned if they didn't fail right there AGAIN! I owe whomever that was a drink though, because again it failed on the ground and not in the air. I didn't even bother hauling her to SEFF with @willsonman and I last month, despite that being the BEST location I've found to fly her.

When I got back from SEFF I had the bug to get her flying again. I think it was looking at John Morgans beautiful models, particularly the new Skyraider. I pulled out all of the actuators and set them up side by side looking for imperfections or failure points. I determined that the failing units seem to be seizing/locking up, perhaps due to dirt or debris (or maybe rust) in the threads. When this happens it appears the main drive motor keeps pushing until the threaded section fatigues and fails. When working smoothly the units should NOT be able to unscrew themselves, but once they've jammed and the motors continue to try to force them into place they can fail permanently.

I found that I have 3 "good" units and 3 failed units, although the motor drive section of all work fine.

So the "fix", I hope, has been found. I liberally applied white lithium grease to the threads and will be making it part of my daily post-flight checks to re-grease them and cycle them a few times to ensure the threads stay lubricated and slick. I also stepped down the voltage on the dedicated BEC for the gear. The maximum voltage for the units is 9v. I had it set to 8.5 volts, but I've now dropped it to 7v. I never had issues with the gear failing like this when I ran lower voltages, but the gear would take close to 30 seconds to pull up. Part of me suspects that the extra torque/power made from the extra voltage is what allowed the gear to stress the threads to failure. At the lower voltages even if the threads got jammed there wasn't enough force to snap the metal.

So that is it for this wall of text. I wish I had a year's worth of flight footage and pictures to share, but her last flights were about a year ago now. That will be addressed ASAP. I put the gear through 50 cycles last night with 0 issues, and found that my 1800 mAh 45C pack could easily do 100+ cycles. I'll be re-greasing them today and will be watching the weather so I can get some flights in before our clubs next warbird event. She will be back in the air soon and hopefully get a lot of air time this season.
 

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willsonman

Builder Extraordinare
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It was me that suggested the additional cycling of the gear but I'm sure Pat will appreciate the beer more :p
She is still such a beautiful bird. Others take note... rotating retracts are no joke to trifle with. The issues I encountered in my Corsair build pale by far in comparison to what Carl has been through here. I'd love to build a F6F but the gear makes me afraid... very afraid.
 

wilmracer

I build things that fly (sometimes)
Mentor
It was me that suggested the additional cycling of the gear but I'm sure Pat will appreciate the beer more :p
She is still such a beautiful bird. Others take note... rotating retracts are no joke to trifle with. The issues I encountered in my Corsair build pale by far in comparison to what Carl has been through here. I'd love to build a F6F but the gear makes me afraid... very afraid.

Well, thank you for that! You probably saved the model! I'll give Patrick the beer in you're honor ;-)

The F6F is one of my all time favorites too, and is on the short list of models I really want to do. Part of me wants to do it the way @nerdnic did his big corsair and make it an ultralight belly lander so I dont have to deal with rotating retracts ever again. I do, however, have a drawer full of rotating retracts from various models that I picked up looking for something cheap that would work with this p40. I Never found a set that would do it (other than the pricey ones) but as a result I have a set that would be perfect for a F6F at about 60" span assuming I built light. I'm also considering building one of the ft p40s, scaled up, and slapping them in. Of course it would be a mini version of my big one. Tough to decide. I'm too tied up with B17 building and job hunting so it doesn't matter now, but we will see what happens ;-)
 

wilmracer

I build things that fly (sometimes)
Mentor
So for 2020 I will be dusting this off and will be making one FINAL change so I can fly the pants off of the her this season. During taxi testing for the greased and functioning main gear the shaft for the actuator on the tailwheel bent... again. This has happened many times and I've just been fixing it, replacing it, or replacing the actuators when they have broken (I had a lot of spares).

I was/am so happy with how the tailwheel is functioning on the B-17 that I picked up another mechanical retract unit from Robart. Unfortunately I picked up one with a fork rather than an offset for the wheel. Part of me doesn't care at this point, but I went ahead and reached out to Robart to exchange the fork for the right-hand offset. I'll have to enlarge the tailwheel opening a bit, fabricate a solid mount, and then put an actuator servo forward in the fuse with a CF rod to actuate. I MIGHT take another crack at the doors and use the method @willsonman used on his jug.

This is the last thing that I SHOULD have done from day 1. I won't be cutting corners to save money on landing gear for big aircraft again. At this size/scale the cheaper stuff just doesn't hold up.
 

Joker 53150

Mmmmmmm, balsa.
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Out of curiosity, what's your take on the size & weight - is it heavy enough to handle some wind gusts, or would it handle better with an extra sandwich or two in it's belly? I've had a couple very lightweight planes in the past which worked great on calm days, but only on calm days.
 

wilmracer

I build things that fly (sometimes)
Mentor
Out of curiosity, what's your take on the size & weight - is it heavy enough to handle some wind gusts, or would it handle better with an extra sandwich or two in it's belly? I've had a couple very lightweight planes in the past which worked great on calm days, but only on calm days.

With the tail wheel, servo, and whatever weight is needed to balance I think I'll be around 23lbs AUW, which is a wing loading of 35.57oz/sq.ft and a cube loading of 11.1. Sport/scale models are generally 10-13 and warbirds tend to be >13. I have yet to fly her in anything more than a gentle breeze, but I think she should be able to handle up to 10mph with gusts a bit higher without too much trouble. I need more stick time before I can really say, but she definitely feels really light for a warbird but not TOO light. She wont be catching any thermals, that's for sure.

I'm pretty sure the wing can handle a lot more weight though so If I need to put a few bricks inside that is always an option :)