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

wilmracer

I build things that fly (sometimes)
Mentor
I wonder if you're running a lower kV motor or a lower pitched prop than I was. Did you help me pull the Caudron out of the tree on the west end of Poplar Ford runway? The behavior of that crash seemed exactly like the P-40. I had a pretty aggressive prop on at the time - 10x7 I think, so not so much on the low end thrust as it needed time to unload when I punched it.

Oh... On the Caudron I think I am using the same 10x7. I'll have to check. It MIGHT be a 10x10. in this case I meant the thrust to weight on the P40 let me pull through. I don't know that the Caudron would have recovered in that situation. I do remember pulling her out of the tree ;-)
 

rockyboy

Skill Collector
Mentor
I'm pretty sure it was completely my pilot error that let the Caudron crash - and thanks for helping me get her down. I wasn't sure if you were helping that time, or if that was the crash Tung helped with, or the one that Mike helped with. I had several to choose from :p I'm just trying to learn what equipment / skill combo you used to save the P-40 so I can do better next time - still have Pysborg's to maiden :D
 

Namactual

Elite member
Yeah... In the moment it didn't fully register to me how close that was. Watching the video is when I really saw how bad it was. I think the really high thrust to weight ratio is what allowed me to recover. I got lucky that I didn't hit those trees though... they are closer than they look.
HeartAttack.jpg

Me^^
I do not think I would have the mental fortitude to attempt to fly something like that.

Seriously though, awesome save! The celebration at the end was well deserved.(y)
 

wilmracer

I build things that fly (sometimes)
Mentor
Short compilation video including shots from the second flight. This has some nicer "low" passes along with some failed landing attempts w/o the flaps. After the stall on day one I think I was gunshy about flying slow and ended up coming in too hot several times. The landing on the second flight got cut off on the camera anyway so I used the full flap landing in the video. Future landings will likely be with full flaps.

 

wilmracer

I build things that fly (sometimes)
Mentor
So... Here we go again! We know she flies, so its time to make a few tweaks and get her buttoned up for FFE. Since SEFF I've flown her one more time and made some minor adjustments to the flap mixing. To be honest she needs a bit more weight IMHO. That is a crazy thing to say about a big warbird, but in this case she flies so light that it actually makes her a bit harder to fly. Right now when I bring the throttle down for landing its like hitting quicksand... I'm sure I can get the hang of it, but since I need to tweak her a bit I'm going to add some weight (functional of course) to help her keep some momentum.

So, here is the checklist I've got at the moment:
  • Repaint and blend wing patches
  • Replace foam wheels with Dubro inflatable tires
    • I'm tired of worrying about flat spots on the wheels if I don't use wheel chocks and while the foam is light it is also stiffer than a "real" tire. It will add the better part of 1lb overall but should improve the reliability. One of the foam tires got chewed up pretty good rubbing on the toe-in adjustment bolt on the retract unit so it had to be replaced anyway. The hub on the dubro units will look more scale too, so that's a plus
  • Place main gear retracts on dedicated battery
    • In the videos you can see how slow the gear operate. This is the gear operating at 5v from the BEC. Robart recommends a dedicated pack and voltage up to 9v for gear this large, so that is what will be done. I'll reprogram a castle creations BEC I have on hand to 9v and will run the gear off its own 3s 2100mAh pack that will be installed as necessary to maintain CG after other repairs are completed.
  • Reinforce fuse repair joints
    • I've found a few points in the fuse where additional support will help prevent future failure, so I'll be adding that.
  • Repaint fuse repairs
  • Reinstall cockpit interior and articulated pilot (OH YEAH!)
  • Change prop and complete new spinner
    • I've decided that she needs a bit more speed and that, while the 3 blade looks awesome, she will be more fun to fly on a 2 blade. I had been running a 20x10x3. I'll be switching her to a prop recommended by scorpion for this motor. On a 21x12 they report that she will make just shy of 3500W, pull her around at a top speed of about 70mph, and still have 1:1 thrust to weight even if the new AUW is 25lbs. I've received the new spinner assembly from Keith Sparks and will have to cut it to fit, but that won't be too hard for a 2 blade.
Wing repainting is underway. The colors match well but will need weathering and some scuffing to blend in with the 3 year old paint.
 

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willsonman

Builder Extraordinare
Mentor
Even if not totally blended, it will look more like a field repair and give her some character. The quicksand metaphor is a good one from the two flights I observed at SEFF. Seemed like you had to keep on at least 1/2 throttle as she slowed down so well. I'm pretty sure everyone will be glad to see here again at FF and new onlookers will be able to enjoy the tale of getting this GORGEOUS airplane in the air.
 

wilmracer

I build things that fly (sometimes)
Mentor
Yeah! Give her a few chips around the repair and some extra rivets and it'll look like a new leading edge skin.

That'ts the hope! There is some "natural" weathering that has occurred over the last few years, some of which I LOVE. There is some hangar rash on the left wing roundel that, to my eyes, looks just perfect. I could have fixed it, but to me it looks like the kind of damage that these things would have endured.

All of the major markings on the P-40 are painted on. The nomenclature markings are rub-on transfers... no vinyl or decals. Last night I repainted sections of the roundels on the wings. There are a few small remaining touch-ups around the gear fairings, but the large stuff is now done on the wing. I'm lucky I still had a paint tucked away from way back. I'll probably move on to the fuse next and let this all cure for a few days before scuffing it up and weathering.
 

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PsyBorg

Wake up! Time to fly!
Thats a detailed plan you have in such a short time to FFO. I agree that what you have done already is a big change. Maybe take some of the "dings" in the paint and give them the make over to a bullet hole instead of bringing it back to picture perfect.

Will the change over from foam tires to rubber make the plan more "bouncy" on landings or will the retracts absorb enough or maybe an adjustment in air pressure in the wheels help with all that?
 

wilmracer

I build things that fly (sometimes)
Mentor
Will the change over from foam tires to rubber make the plan more "bouncy" on landings or will the retracts absorb enough or maybe an adjustment in air pressure in the wheels help with all that?

I actually anticipate it making landing a bit smoother. The foam wheels are very light, but also very firm. The foam wheels themselves have almost no shock absorption and pretty much transfer all of the landing loads to the struts. The inflatable tires will have more give to them and will soak up some of that energy. I did non-scientific side by side bench test dropping both wheels side by side and the bounce for the foam was a bit more than the rubber. I'll redo the test once I tweak the psi, but in any case the convenience and durability of the rubber is the real reason.

As for the timeline... I looks like a lot but honestly it isn't THAT bad. I figure a few hours of work for the reinforcements, 2-3 evenings to do the repaint on the fuse, another evening to reprogram the BEC for 9v and make up a wiring run to the Robart controller, and an evening or two to deal with the new spinner and prop. I may shoot a video on "scale" prop detailing and balancing but that is only if time allows.

Strapping the pilot back in and re-programming is probably just one more evening, and then another evening to put her on the Vanessa rig and re-balance. I'd like to get another flight or two on her before FF to validate the new prop setup and to record some data for setting airspeed alarms. After that its time to fly the pants off of her :)
 

wilmracer

I build things that fly (sometimes)
Mentor
Wing repairs and modifications are now complete (minus the weathering that will be completed once the fuse is done). That means I can scratch the first three bullet points above from the list.

Reprogramming the BEC to 9v was dead simple, and I soldered up some 16 gauge wire with an xt30 for battery connection. I'll be making an extension that will run through the fuse to wherever the battery ends up, but the XT30 will be easy enough to connect will hooking her up. I also added a small ply plate to support the joint of the 16 gauge wire to the thin BEC wires. This area could get tugged a bit every time I connect/disconnect the wing and I don't want to loosen the connection to the BEC and run the risk of gear failure. I'll squirt a bit of silicone adhesive in here and that should keep it happy.

Here they are in action

The last few small holes in the wing were filled with epoxy+microballoons, smoothed, and painted and the vacuum formed gear fairing was patched up on the right side. The wing has been set aside and the fuse is on the bench. Probably won't get much done until next week but she's moving along.
 

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wilmracer

I build things that fly (sometimes)
Mentor
Getting close to knocking out a few more bullet points from above. The additional areas of cracked foam were opened up, patches placed inside, and strips of glass laid down on the outside. Should finish curing out later today and be ready for sanding and primer tonight. Started painting up the new 21x12 prop. Need to get started on the replacement spinner but cutting it for a 2 blade should be pretty simple.

While re-wiring and tweaking the pilot figure I stumbled upon something in my radio programming that I SHOULD have caught. When doing the bench testing of the 3 blade propeller apparently I adjusted the endpoints on the throttle travel and I was only getting 85%. I THINK I had calibrated the ESC after that had been set, so in theory I think I should still have been getting 100% of the available power, but I'm not sure. She may have had a bit more top end available. In any case I'll need to re-calibrate the ESC when the new prop and spinner are on and I think I'll be happy with the performance.
 

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wilmracer

I build things that fly (sometimes)
Mentor
Patches have been repainted. Going to let the paint cure out a few days before blending it but it already looks a lot better. Panel lines pop a bit too much at the moment but will dull out once the paint is roughed up and weathered.

Found a dead servo in the pilot so started replacing that, but now I'm thinking I may redo the pilot mechanism completely. There is a TON of slop in it and I just want it reliable long term. That will be a project for this weekend, along with rebuilding some of the cockpit interior that wasn't salvageable after the initial crash years ago.
 

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wilmracer

I build things that fly (sometimes)
Mentor
Made some progress last night. Thought I'd get more done but I've been distracted by the NHL finals. Been a Washington Caps fan since I was a kid and it looks like this may FINALLY be their year.

  • New cockpit side panels are painted up. I'll add a bit of detailing and then glue them in tonight.
  • Pilot is rewired with new head servo and some guards were installed to ensure the clothing didn't foul the servo linkages. The arm servo still has a bit of trouble with lifting the arm, but removing a bit of the padding will resolve that. Once the side panels are installed I'll get him permanently installed. He is held to the seat with some velcro and double-sided tape, but the harness is actually functional and will do a pretty good job holding him in by itself.
  • Got the new spinner turning true and then got it marked and cut for the 2 blade prop. Looks pretty good so far. Tonight I'll install the two remaining retention screws, transfer my alignment marks to the inside, scuff her up with some 120 and shoot some primer. Then she'll get the same olive green as the fuselage.

Should have her back on the Vanessa rig to re-balance by this weekend. Then it is on to prepping other stuff for Flite Fest!
 

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Grifflyer

WWII fanatic
  • Got the new spinner turning true and then got it marked and cut for the 2 blade prop. Looks pretty good so far. Tonight I'll install the two remaining retention screws, transfer my alignment marks to the inside, scuff her up with some 120 and shoot some primer. Then she'll get the same olive green as the fuselage.

Woah Woah Woah, Slow things down a bit, That spinner is supposed to be red, not some....some...olive green, just look at my avatar:p

But anyways progress is looking very good.
 

wilmracer

I build things that fly (sometimes)
Mentor
Woah Woah Woah, Slow things down a bit, That spinner is supposed to be red, not some....some...olive green, just look at my avatar:p

But anyways progress is looking very good.

To be honest I'm considering it. I know a lot had the red nose. Just not sure how it would look on this one. I'll give it some thought.
 

PsyBorg

Wake up! Time to fly!
Boy that pilot has one long middle finger. Is that to "Keep up Foreign Relations" like in the movie Top Gun?