P-38 - The Ultimate EPO Lightning

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Official Black Horse 1724mm Dornier DO335 Pfeil ("Arrow") Thread

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  • MrSmoothie Your mods on this bird are really taking it to the next level. Well done!

    I had thought about opening up the rear cowl aft vents as well. Then the thought occured that doing that might cause all of the air to completely bypass the rear motor.

    My attempt to get air to the rear motor are to leave a little extra gap between the rear cowl motor opening and the spinner. In addition, I had Tru-turn do my rear spinner with the lightened back plate and a little more space around the rear prop blades. The hope is that this combination will draw the air from the three open scoops over and around the motor.

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    • For a bit of a challenge, I decided to play around with the stock pilot to see if it could be made to be usable. The bulbous head was reduced, arms adjusted, some scale details and paint added. Not perfect but, I might just use it.

      Also wasn't a fan of the gun blisters on the glue on slab. So, they were cut out, filled with balsa and sanded. CF tubing barrels were added as well.

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      • I've got my Do335 as far as I want to go before I maiden it -- looks like Friday morning has the weather I'm looking for and gives me a few more days to check a few functional things without rushing. Today was the first time I put everything together, although I did not tighten down (nor run) the props.

        If you want to see more details and pics, go to my build log last page: https://www.rcgroups.com/forums/show...1#post44426285

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        • Looking good, Nick! Don't forget to do good motors-on range checks. With those motors and long cables, you'll want to do a good range check, to make sure that the motors and high-amp lines aren't messing with the RX. After I nearly dumped my Freewing A-10 because the motors were causing the ailerons to fail (bad solder joint that I didn't detect with a motors-off range check.), I religiously do motor-on range checks now.
          ---
          Warbirder

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          • Oxotnik Did you get the spinner I sent you? If so, did it work for you? I am still waiting for my Tru-Turn to show up for the front motor....

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            • Originally posted by downwind3zero View Post
              Oxotnik Did you get the spinner I sent you? If so, did it work for you? I am still waiting for my Tru-Turn to show up for the front motor....
              Yes, I did receive it. It looks great. Many thanks! Unfortunately, I've gotten busy with other things and haven't gotten around to installing it.
              ---
              Warbirder

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              • [QUOTE=Terminater007;n250224]Here's a Old video of my Do335 before I sold it
                That's running a 14x7 apc on the front and a 14x8.5 apc prop on the rear. takeoff is using half flap Landing's with full flap need to be nice and flat. ...

                I had been thinking a higher pitch prop was needed at the rear. Was there a reason based on findings which had you installing a higher pitch prop at the rear?

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                • I was reading a article on Wiki regarding push - pull configurations that the rear prop operates in disturbed air from the front that decreases its efficiency so I thought I would use higher pitch on the rear.
                  And it seemed to work very well in my case.

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                  • I was reading a article on Wiki regarding push - pull configurations that the rear prop operates in disturbed air from the front that decreases its efficiency so I thought I would use higher pitch on the rear.
                    And it seemed to work very well in my case.
                    On the Black Horse Pfeil? And if so, what props did you end up with? I'll be trying out 16x10x3's (C/R) same as Oxotnik in the morning.

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                    • I'm happy (OK, elated) to report that I flew my Pfiel twice this morning. The first takeoff was a near-disaster with the plane nosing up immediately and doing the "let's stall happy dance" -- not sure how I managed, but I got it under control long enough to get the half-flaps up and lots of down trim dialed in. Then I was able to fly fairly normal and have a surprisingly good landing.

                      My conclusions: off of Geotex, half-flaps not necessary. Too much up trim, too much elevator travel, not enough expo. Tail heavy.

                      Added 4.5 oz to the firewall, adjusted the elevator and flew again. Second flight was close to perfect from takeoff to landing. Did several rolls and one Immelmann. Concluded I had too much aileron travel and dialed that back later. Very impressive plane in flight.

                      Now I can go back to the shop and do a few more things I was waiting on until the maiden.

                      I flew with Roaring Top 6250 35c today, as far forward as I could go and still get the front of the hatch engaged. I'll be looking at possible options for a somewhat larger lipo that could position further aft in the compartment, and allow me to remove the weights -- might as well have more mAh.

                      My big takeaway today was that my biggest fear -- that of landing -- was unwarranted. With half flaps it was very easy to land, even on the first flight with everything out of whack. I posted details and a rough low-res video on my RCG build thread while I wait for the high res video segments to be uploaded to me for editing. You can see just how close I came to a total catastrophe on a model that was "this close" to being "just right."

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                      • Congrats!

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                        • Congrats, again, Nick. Great save on the Maiden and a beautiful second flight.
                          ---
                          Warbirder

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                          • Congrats on the maiden. That first takeoff had the pucker factor going for sure, nice save, always keep flying it.

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                            • So, Nick, now that you've got two flights under your belt, did you have any observations that were different than the flight observations that I've posted?
                              ---
                              Warbirder

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                              • NICE!

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                                • So, Nick, now that you've got two flights under your belt, did you have any observations that were different than the flight observations that I've posted?
                                  First, let's discount my first takeoff -- too many adjustments out of whack. I'm still trying to forget it.

                                  I found the plane very stable -- I reduced throws on the elevator of course after the first flight, and dialed back the ailerons after both flights. The first time I rolled it, the plane rotated like it was on a spit. Later slow rolls were great with little to no correction while inverted. This is definitely a plane with no need for stabilization of any type. I thought the second takeoff was excellent -- very easy to keep going straight and it essentially took off when it was ready, with no flaps at all (from Geotex runway). I was a little concerned when I made the first Immelmann; whether it would get over the top easily or barely -- it was no problem at all. It wasn't that wide of an arc, however, and I'd like to open it up a little more next flight and see how it does. I'm not an "inverted flying" guy, so I didn't try that.

                                  As I said, both landings couldn't have been easier, including the first that still had touchy controls and aft CG. Both were fairly flat approaches. I think I made the right move, landing on the grass strip both times -- settled right in with no bounce or anything. Half flap seemed to be just fine, which surprised me -- I normally land all my warbirds with full flaps cranked as far as they'll go. I honestly don't know if I ever tried full flaps at all, or did for a little and went back to half. But I'm sure both landings were half-flap, and if I can replicate those two landings going forward, there's no reason to change.

                                  BTW, I had no shimmy of any kind on my full-throttle passes. At first you might think it's not going all that fast, except when you consider how big it is -- that can be deceptive, speed-wise. I think it was going plenty fast. But clearly, it flies and handles very well at half-throttle or a little more.

                                  I'm really looking forward to flying it again, I can tell you that! The only change I've made for the next flight is reducing aileron throw a bit and adding a little more expo. I generally don't fly with multiple (low/med/high) rates -- I get it to where I like it and leave it.

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                                  • I got around to editing some video my father took with his iPad, including the nearly disastrous first takeoff. He ducked for cover so didn't get all of it. He also missed the smooth second flight takeoff (it was!), so points off for that, haha.

                                    Around the 7 minute mark I did a high speed pass -- more impressive when you realize this is nearly six feet long.

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                                    • Question for Alpha, if you are watching:

                                      What kind of paint was used for the canopy frame? I had a helluva time removing it, as it did not react to the usual assortment of solvents. In the end, I had to use Strypeeze which is pretty heavy duty, which dulled the clear plastic a little. Usually isopropyl alcohol takes the paint off of canopies, but that didn't touch it, nor did acetone. I don't think I had any lacquer thinner to try, but now I'm wondering about that.

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                                      • I got in another flight of my 335 today. Perfect take off, great flight. Rolls were nice (although I think that i'm going to increase my aileron throws a touch, to speed up the roll rate) and the Immelmans were each (l like the throw of the elevator). On my first landing approach, I almost dumped her as I was turning onto final. All my fault. I'd let her get a little slow and the bank angle too steep. I think that I also hit some turbulence coming off the end of the trees down there (a known problem on windy days). Luckily, I still had plenty of altitude and was able to easily recover from the stall, climb back out, and go around for a better approach, although I still wasn't happy with the landing. My poor old heart was beating 90-to-nothing after the previous botched approach and I think that I was just too damn tense. the landing wasn't horrible, but just barely. As you can tell from my groan at touchdown, I'd been expecting a bad slap-down, but I managed to round out the landing angle just in the nick of time. Better lucky, than good, right? LOL



                                        Just for completeness.
                                        Flight weight: 16.5 lbs
                                        Motors: Freewing 5055-390Kv
                                        Props: MAS 16x10x3
                                        Battery: 6S-8AH
                                        CG: at Mfg Suggested Location

                                        Flight time: about 5.5 minutes
                                        Battery remaining after flight: 50%
                                        Max Speed (ground speed, per FrSky GPS sensor): 87mph, with a 10 wind (so, assume that the max airspeed was 77 mph)
                                        ---
                                        Warbirder

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                                        • I can't wait for these to come back in stock, I missed my window of opportunity on the first batch, but I bet it will go well with my Extreme Flight FW-190 Red Tulip. I can not wait!

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