P-38 Lightning Brotherhood
#502
Thread Starter
My Feedback: (24)
Thanks guys
The cowlings are shaped for 2.5" spinners. Thinking it needs 4" spinners, so no spinners this year...better for cooling anyways
Downloaded ESCs last night, and while it looked good, it was not happy. It looks like it maxed out at takeoff at 107 amps @ 25.3 volts, or 2709 watts each side...thats why it jumped in the air. I was pretty much holding it down on 1/2 the takeoff run. Anything above 80% throttle was just making heat at 104-105 amps. Looks like it maxed out right around 90-95 MPH on high speed pass. Having the video was a huge help when looking at the data. When it makes the pass at 1:17, that was at 63% throttle, and it was doing roughly 70 MPH. That actually seems like a good speed for it
So, going to try the MA14x9x3, and MA 16x10x3. Also going to trim the props I used in that flight, APC 15.75x13x3. My prop calculator shows that trimming .625 off the tips will drop the load by 700 watts at 7000 RPM, or 1000 watts at 8000 RPM. Taking .75 off each tip will drop it 840 watts at 7000, or 1258 watts at 8000. Of coarse, if I could control my thumb, could get away with this setup as is, flying it between 50-80% throttle, but need good ESCs to get away with that
The APCs are nitro props, and are REALLY loading up the motors. Graupner makes an electric 16X12X3 Sonic prop which might be perfect on this, but I can't seem to find them in the US. If anyone 's got some insight on where to get them, please let me know
The cowlings are shaped for 2.5" spinners. Thinking it needs 4" spinners, so no spinners this year...better for cooling anyways
Downloaded ESCs last night, and while it looked good, it was not happy. It looks like it maxed out at takeoff at 107 amps @ 25.3 volts, or 2709 watts each side...thats why it jumped in the air. I was pretty much holding it down on 1/2 the takeoff run. Anything above 80% throttle was just making heat at 104-105 amps. Looks like it maxed out right around 90-95 MPH on high speed pass. Having the video was a huge help when looking at the data. When it makes the pass at 1:17, that was at 63% throttle, and it was doing roughly 70 MPH. That actually seems like a good speed for it
So, going to try the MA14x9x3, and MA 16x10x3. Also going to trim the props I used in that flight, APC 15.75x13x3. My prop calculator shows that trimming .625 off the tips will drop the load by 700 watts at 7000 RPM, or 1000 watts at 8000 RPM. Taking .75 off each tip will drop it 840 watts at 7000, or 1258 watts at 8000. Of coarse, if I could control my thumb, could get away with this setup as is, flying it between 50-80% throttle, but need good ESCs to get away with that
The APCs are nitro props, and are REALLY loading up the motors. Graupner makes an electric 16X12X3 Sonic prop which might be perfect on this, but I can't seem to find them in the US. If anyone 's got some insight on where to get them, please let me know
Last edited by 70 ragtop; 06-28-2014 at 06:33 PM.
#503
Thread Starter
My Feedback: (24)
Found them
http://www.allerc.com/props-graupner...1&sort=model-a
Didn't know they had a 18X12X3. That might be a good prop for the electric Yellow P-38s
http://www.allerc.com/props-graupner...1&sort=model-a
Didn't know they had a 18X12X3. That might be a good prop for the electric Yellow P-38s
Last edited by 70 ragtop; 06-18-2014 at 07:00 PM.
#504
Thread Starter
My Feedback: (24)
Managed to get out and try a couple more props on the NP-38. The first two flights were with APC 15.75x13x3 props. Performance was great, but was over amping the motors at full throttle. Flight 3 was flown with G Sonic 16x12x3, and flight 4 was with MA 16x10x3. Performance was down from the previous flights, but that was expected. The G Sonics are very nice props, and would say slightly faster than the Master Airscrews, but with no prop rip, and lower amp draw. The MAs were making a bunch of noise, it sounded fast, but wasn't. Did not bother with the 14x9x3s, as ground runs showed they are too small for this plane
Personal preference comes into play here, but the numbers show that both these props are a good fit for these motors on this plane. Takeoffs are quick and effortless, vertical is good, and it flys in a typical sport scale manner. That said, top end speed is down. Did not fly the cut down APC props yet, but static runs showed a 1000RPM increase, and watts dropped a couple hundred.
All these props are in the 2200-2500watt range on the ground, but what is really important to me, is what its doing in flight. The MA and G sonic props both unload in flight, and are well within the continuous rating for the motors, the 13 pitch, three blade APCs do not. Too much drag, not enough speed for them to unload
Will post ESC downloads so those interested can see how these props load up the motors
Look at the trees and grass in the back ground. There wasn't a soul around at the field as the wind was blowing 25-30 kts..way too windy to go flying. One time that the small verticals are a benefit, it handled the wind like a champ.
Personal preference comes into play here, but the numbers show that both these props are a good fit for these motors on this plane. Takeoffs are quick and effortless, vertical is good, and it flys in a typical sport scale manner. That said, top end speed is down. Did not fly the cut down APC props yet, but static runs showed a 1000RPM increase, and watts dropped a couple hundred.
All these props are in the 2200-2500watt range on the ground, but what is really important to me, is what its doing in flight. The MA and G sonic props both unload in flight, and are well within the continuous rating for the motors, the 13 pitch, three blade APCs do not. Too much drag, not enough speed for them to unload
Will post ESC downloads so those interested can see how these props load up the motors
Look at the trees and grass in the back ground. There wasn't a soul around at the field as the wind was blowing 25-30 kts..way too windy to go flying. One time that the small verticals are a benefit, it handled the wind like a champ.
Last edited by 70 ragtop; 06-26-2014 at 03:39 PM.
#506
Thread Starter
My Feedback: (24)
Did flights 5-7 today, and have settled on props. The best three blade prop (best looking to) at this power level are the G Sonic 16x12x3. The best performance, while still staying within limits, is an APC 16x12E two blade. Video is of flight 6 using those props. It was the worse landing of the day, I was a little fast and both mains unlocked when it touched down (Robart spring airs). Bounced it and they locked. Right main unlocked twice today??
Three minute flight used 2.73Ah out of 9.3Ah capacity per boom, most of it WOT. A 5000mah pack per side is plenty, I'm just carrying extra weight around. Landed with batteries at 70% left....great little motors
Hope the info is helpful.
https://www.youtube.com/watch?v=GgTp3cGyN9s
Three minute flight used 2.73Ah out of 9.3Ah capacity per boom, most of it WOT. A 5000mah pack per side is plenty, I'm just carrying extra weight around. Landed with batteries at 70% left....great little motors
Hope the info is helpful.
https://www.youtube.com/watch?v=GgTp3cGyN9s
Last edited by 70 ragtop; 06-29-2014 at 10:13 AM.
#508
Thread Starter
My Feedback: (24)
Little more from flight 5 with cut down APC 15.75x13x3. Took .600 off each tip. I really like the way it flys with those props, but its still pulling a too many amps for a long and trouble free life. Thinking about switching motors for 10S so it can spin uncut APC 3 bladers for next season.
https://www.youtube.com/watch?v=O7_b8zR8jro&feature=youtu.be https://www.youtube.com/watch?v=-ohsfPGK-Go&feature=youtu.be
https://www.youtube.com/watch?v=O7_b8zR8jro&feature=youtu.be https://www.youtube.com/watch?v=-ohsfPGK-Go&feature=youtu.be
Last edited by 70 ragtop; 06-28-2014 at 06:31 PM.
#510
Thread Starter
My Feedback: (24)
Enjoying the Nitro P-38 so much, decided to change plans and finish up the Yellow model next. Tried a couple motors, several props, and did some taxi tests this past weekend. The G Sonic props look great and pull hard, APCs look a touch small, but pull very hard.
Pulled everything out and started sanding the Hysol. Can report it sands easily, and seems to be a good alternative for filling cracks. It is obvious I'm not gong to be able to save any of the panel lines on the pod. Will have to redo those with primer, same for the booms by the radiator scoops. Should be able to scrap the paint out of the panel lines on the rest of the plane, and only need to touch them up. Seriously thinking of just getting it to the primer/panel line stage, and flying it
Pulled everything out and started sanding the Hysol. Can report it sands easily, and seems to be a good alternative for filling cracks. It is obvious I'm not gong to be able to save any of the panel lines on the pod. Will have to redo those with primer, same for the booms by the radiator scoops. Should be able to scrap the paint out of the panel lines on the rest of the plane, and only need to touch them up. Seriously thinking of just getting it to the primer/panel line stage, and flying it
Last edited by 70 ragtop; 07-21-2014 at 06:47 PM.
#511
Join Date: Nov 2005
Location: , SC
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
I notice you got a CC pro bec, which is also what Im running in my P-38. I don't really know how much difference it would really make running of one side, but Im using a thunder power 2s 3800 on the bec. To me, its a $60 insurance policy and its less strain on the bec since its only dropping the voltage from 7.4.
http://www.horizonhobby.com/products...-THP38002SPPRX
Just my .02
Travis
http://www.horizonhobby.com/products...-THP38002SPPRX
Just my .02
Travis
Last edited by edf nut; 06-30-2014 at 03:40 PM.
#513
Thread Starter
My Feedback: (24)
Thanks Travis
I'm not sure how I'm going to handle RX/servo power yet, but need to have some sort of redundancy. Right now, I'm thinking one RX in each boom, to cut down on the amount of wiring/complexity. Each RX powered by its own BEC. Spoke with the Castle folks at the Wram show, and they said not to run two BECs together; some sort of switching is needed. Since the Castle pro has two power leads, would have been easy to run one line from each BEC to each RX. Only thing missing is some sort of indication that one BEC had failed
Had the old Jomar battery backer in my jet days using NiCad's. Would give you a red LED if the unit switched from primary to secondary battery in flight.
Saw something similar for lipos in one of the other threads, and of coarse there's powerbox type products.
I have a couple of the Power safe RXs. They are supposed to be designed to run two regulators. Not sure if it is something different with the Castle pro BECs, or if there is something inside the powersafe RXs that allow you to tie two BECs together?? I always though you could tie two together with a diode inline, but the Castle rep said no
I'm not sure how I'm going to handle RX/servo power yet, but need to have some sort of redundancy. Right now, I'm thinking one RX in each boom, to cut down on the amount of wiring/complexity. Each RX powered by its own BEC. Spoke with the Castle folks at the Wram show, and they said not to run two BECs together; some sort of switching is needed. Since the Castle pro has two power leads, would have been easy to run one line from each BEC to each RX. Only thing missing is some sort of indication that one BEC had failed
Had the old Jomar battery backer in my jet days using NiCad's. Would give you a red LED if the unit switched from primary to secondary battery in flight.
Saw something similar for lipos in one of the other threads, and of coarse there's powerbox type products.
I have a couple of the Power safe RXs. They are supposed to be designed to run two regulators. Not sure if it is something different with the Castle pro BECs, or if there is something inside the powersafe RXs that allow you to tie two BECs together?? I always though you could tie two together with a diode inline, but the Castle rep said no
#514
Thread Starter
My Feedback: (24)
I said the Hysol was working out good as a crack filler, and I wanted to clarify that statement. I applied a skim coat that filled all the cracks on the lower half of the nose a couple months ago. The surface was roughed up, prepped and clean before hand. As I sand now, I noticed that when the Hysol gets thin, it starts coming up. As a result, I ended up sanding it all off. It holds strong where it is filling voids, as I could not dig it out, but on a flat surface, when used like bondo, or filler to level, or taper out across a surface, its the wrong product
You don't know unless you try!
You don't know unless you try!
#515
My Feedback: (37)
Best glue for that polyester fuse is just fiberglass the inside with 6oz strips and outside with 2oz cloth using polyester resin from the automotive store. Hysol is epoxy, you will get a bond but not as good as the same polyester material that was used. Also, 1/4 overlap fiberglass on the cracks is all it needs to be strong again. Be careful which polyester resin you use some are not sand-able, the automotive version sands well.
Last edited by fw190; 07-07-2014 at 09:21 AM.
#517
Thread Starter
My Feedback: (24)
Thanks for the info guys.
Was trying to use a product in a way it was not intended, and it didn't work out.......oh well.
Panhandler
Got your PM, and think I responded but the system went down last night, and I'm not sure if went thru
I got the G Sonic props at All E RC.
http://www.allerc.com/props-graupner...1&sort=model-a
Was trying to use a product in a way it was not intended, and it didn't work out.......oh well.
Panhandler
Got your PM, and think I responded but the system went down last night, and I'm not sure if went thru
I got the G Sonic props at All E RC.
http://www.allerc.com/props-graupner...1&sort=model-a
#518
Thanks for the info guys.
Was trying to use a product in a way it was not intended, and it didn't work out.......oh well.
Panhandler
Got your PM, and think I responded but the system went down last night, and I'm not sure if went thru
I got the G Sonic props at All E RC.
http://www.allerc.com/props-graupner...1&sort=model-a
Was trying to use a product in a way it was not intended, and it didn't work out.......oh well.
Panhandler
Got your PM, and think I responded but the system went down last night, and I'm not sure if went thru
I got the G Sonic props at All E RC.
http://www.allerc.com/props-graupner...1&sort=model-a
#519
Thread Starter
My Feedback: (24)
Anytime
You going to try it with the Rimfires, or Scorpions? I added more battery weight to negate the big CG shift when gear retracted, and it ended up at 22.5 lbs. That gives it a wing loading of roughly 45oz/sq ft. At that weight, it fly's like a pussxcat..very easy, and enjoyable plane to fly.
BTW, I posed the question about the big CG shift I was having, and was reminded to just figure the MAC. That's exactly what I did, and here's some pictures of where I put it. Just in front of the flap servo is where the manual says to put it, which is actually pretty good. With the extra battery weight, my CG shift was down to a little less than 3/4". I balanced it on the 25% MAC line gear down. With gear up it balances right on the flap servo screw heads, or slightly aft of where the manual calls out. It flys very nice there, does not feel heavy at all. If anything, to fly like a typical warbird (heavy) could stand to move it fwd a little, but I'm going to leave it right here it is.
You going to try it with the Rimfires, or Scorpions? I added more battery weight to negate the big CG shift when gear retracted, and it ended up at 22.5 lbs. That gives it a wing loading of roughly 45oz/sq ft. At that weight, it fly's like a pussxcat..very easy, and enjoyable plane to fly.
BTW, I posed the question about the big CG shift I was having, and was reminded to just figure the MAC. That's exactly what I did, and here's some pictures of where I put it. Just in front of the flap servo is where the manual says to put it, which is actually pretty good. With the extra battery weight, my CG shift was down to a little less than 3/4". I balanced it on the 25% MAC line gear down. With gear up it balances right on the flap servo screw heads, or slightly aft of where the manual calls out. It flys very nice there, does not feel heavy at all. If anything, to fly like a typical warbird (heavy) could stand to move it fwd a little, but I'm going to leave it right here it is.
#522
Thread Starter
My Feedback: (24)
I'm not sure about getting J power servos, but should be able to get replacements without much trouble. I took the retracts out of mine as it is a park flier. I'll will look thru my servo drawer and see if I saved them. Otherwise, any place that sells less expensive servos should have something that will work. J Power lists 9G servos, I like Motion Hobby for this sort of thing
http://www.motionrc.com/servos/
http://www.jpower.hk/P38.html
http://www.motionrc.com/servos/
http://www.jpower.hk/P38.html
Last edited by 70 ragtop; 07-09-2014 at 07:26 PM.
#523
Thread Starter
My Feedback: (24)
New props arrived today. Got no response from Fialia, so going to try Ramoser Vario Prop 17.9" adjustable pitch props, left and right hand rotation. Vario Prop also offers a 19.9" blade for the same hubs. I know 20" will look better, but 18" will be a little faster while using less power .....more speed and longer flights is hard to resist
http://www.ramoser.de/home_e/variopr...rioprop_e.html
How do you guys think they look, size wise?
http://www.ramoser.de/home_e/variopr...rioprop_e.html
How do you guys think they look, size wise?
Last edited by 70 ragtop; 07-21-2014 at 06:49 PM.
#525
My Feedback: (1)
Ragtop, those look great! I also have the vario prop setups...two three blade set ups(109emil &109Fritz)running off of power 160 motors, and one 4 blade set up for my 80" razorback P-47 with an AXI5345-14 motor, all running the 19.9" blades. I can't remember what motors your using? Make sure you watch his uTube videos, as he gives you a few good tips for initial setup of the prop systems. I think the size looks about right...not too small and not overly large compaired to the airframe.
I'm just getting ready to do some ground testing with mine,(three blades systems) so I can't give you any numbers as of yet...please share your experiences and I'll do the same. I really think these props are an excellent choice when going with an electric set up, as u can "dial in" your motor to adjust max amp draw.
By by the way true turn makes replacement prop adapters that are longer, to allow enough thread to use the prop washer and nut that your motor originally came with(thickness of hub won't allow use of these without doing this, as you probably know by now!)
anyways they look great on your lightning! I can't wait to see your yellow completed!
silently lurking! Lol
Casey
I'm just getting ready to do some ground testing with mine,(three blades systems) so I can't give you any numbers as of yet...please share your experiences and I'll do the same. I really think these props are an excellent choice when going with an electric set up, as u can "dial in" your motor to adjust max amp draw.
By by the way true turn makes replacement prop adapters that are longer, to allow enough thread to use the prop washer and nut that your motor originally came with(thickness of hub won't allow use of these without doing this, as you probably know by now!)
anyways they look great on your lightning! I can't wait to see your yellow completed!
silently lurking! Lol
Casey