All-New Freewing PJ50 Twin 70mm EDF Jet - Official Thread

[Hugh Wiedman]

BTW Hugh, unloading batteries inside your truck could be dangerous. Especially when you are on the road. One of our club members had a 5000 5S, for his pattern plane, went off in the car. Lucky he tossed it out ASAP. But the toxic smoke stuck to the car for a while.

Now, while driving, I always keep batteries where they can be easily accessed. His words "if one goes off, toss it in someone else car! It's their problem now!" lol 😂

Great advice, thanks. I do keep it on the console next to me while driving so now I'll keep an eye out for the nearest car to toss out quickly! Had one go off in my home office/hangar one day when I first started flying and at the time I had no idea what a Lipo was or how dangerous it could be. It had puffed badly (an E-Flight battery of course) so I came up with the brilliant idea that I'd just pop it with a pin to release the pressure. Holy cow, flames and smoke belched out and I grabbed it by the leads, running through the house and threw it on the cement floor of the garage. It promptly burned a hole in the cement and took me a couple of hours to clear the smoke out of the house. Needless to say my CO was not a happy camper!

[GliderGuy]

After having now logged 73 flights on the PJ50, I have some well-healed information to offer....somewhat counter to my prior posts. Hey...I'm learning!

**Edit: Enzo’s comments down thread made me measure my flap travel. My max flap throw is LESS than the manual. I will leave it, but take this into consideration when reading my post below.

• I take it back...she DOES need aileron expo. In fact, 40% seems about right. Without it, she'd just too twitchy in windy conditions on final approach. Without expo, it is so easy to get into a rapid wing rock/over control situation on final when slowing down. Try it...you'll be pleased with how much this tames her down on final approach.
• I'm beginning to think that 5 or 10 mm aft of the Molded CG mark will be a better place for the CG. More than a couple of times, she's gotten into a bucking broncho type of crow hop like the A-10 does. Moving the CG back on the A-10 greatly reduces the crow hop for the A-10 (if not even eliminates it). I'm thinking the PJ50 needs a more aft CG to minimize the tendency. If you hit fast and hit a bump after touchdown or touch slightly nose wheel first...watch out! It has happened 5 times. UGH. Luckily, the lighter front end of the PJ50 doesn't put the same stress on the nose gear like the A-10 does. I have not see any damage from any of the 5 crow hop events. Just embarrassing to the max and had me scratching my head afterwards,
• Man...sooo important to really slow down in the pattern. I use about 25%** power on downwind...reducing to maybe 10%** on base and then 5% on final then I kill the throttle while still quite a short of the threshold. If you don't slow down in the pattern and chop power short of the threshold YOU WILL LAND LONG!!!! She does not bleed energy very fast at all even with full** flaps.

-GG

[xviper]

If you don't slow down in the pattern and chop power short of the threshold YOU WILL LAND LONG!!!! She does not bleed energy very fast at all.

"Thrust Reverse, man, that's what life is all about" ................. bastardization from Phantom of the Paradise.

[GliderGuy]

"Thrust Reverse, man, that's what life is all about" ................. bastardization from Phantom of the Paradise.

I totally agree. My comments are for those who don't yet have it. Fortunately, I have access to some LARGE areas of pavement, so not an issue for me. But....I can sure see where a short runway is gonna give someone fits.

-GG

[Enzo_K]

25% throttle full dirty downwind might be a little risky for me. I normally keep it at over 40% on that downwind turn.
Could it be the aft CG you have made it "floaty"? Full flap feels too draggy for me. I actually land it better with half flap. Read the same comments from Soltproductions on Youtube the other day. I might lower the full flap setting to 20-24mm next time.

[Enzo_K]

Here are some shorter clips from the maiden flight. You can really hear the wing slicing through the wind in this one.

https://www.instagram.com/p/CadecoJujop/

[GliderGuy]

25% throttle full dirty downwind might be a little risky for me. I normally keep it at over 40% on that downwind turn.
Could it be the aft CG you have made it "floaty"? Full flap feels too draggy for me. I actually land it better with half flap. Read the same comments from Soltproductions on Youtube the other day. I might lower the full flap setting to 20-24mm next time.

Hi Enzo, I still am balanced at the molded CG marks. Moving the CG back was a suggestion to possibly minimize the crow hop potential like it helps with the A-10.

I remeasured my flaps. Full deflection is less than the manual shows. This may be the cause of the tendency to float and why I can use less throttle in the pattern. I think I will leave it as is. It does land nicely “most of the time” when I don’t screw up.

-GG

PS I edited post #382 to indicate less than book max flap travel on my bird so as not to mislead others.

[MeyerVW]

What a great flying aircraft. Like most foammies it is not a fan of crosswinds but does handle them if you have quick fingers. Flies very nice and fast at half throttle. To me it flies like the Me262. 6s 5000 100c spektrum battery. I got 3.5 min flight plus a few seconds but the battery was at 40% so its efficient. I went with the book for the throws at full but then I drop them 10%. full throw is 100% and then you can switch to 90 then 80 percent. Expo is at 30%. I flew around at 90% throws and its nice. Very responsive aircraft as well.

[Enzo_K]

I don't about Mikey but both xWiper (banned now) and foamKrasher (from RCG) are one in the same. "Pitts" is NONE of the aforementioned. I think Pitts is just another older fellow who gets confused a fair bit. But like EvanD said, I'll cut him some slack (due to his "condition").


Thanks for the back up, Hugh. There are many of that kind at RCG and most of them are ignored as they have some serious mental health issues. In my last career, I've seen them in real life and now I see them all over the internet. That's life.

U are right Xviper. Thats the sad news for the internet. "don't have to worry about getting punched in the face" Instead of sharing experience and info with the community. A lot of people go online thinking others are just monkeys. Finding that last bit of self-esteem by assuming others are inferior. 🤨 I call it the "show off" syndrome.

[Enzo_K]

Not sure about that, but it makes sense that you could. On the other hand, the discharge amperage is still the same and I suspect you wouldn't save any time by doing that. If you discharge say a 6S 6200 mah, takes about 15 minutes or less. Hooking them up in parallel, now your discharging in effect a 6S 12,400 mah equivalent battery which would take like 30 minutes. I could be wrong, as I'm no electrical genius, but that's just what I'm thinking. Anyway, for me, this is a big time saver as I can discharge any batteries I didn't use at the field in my car on the way home. I've noticed that, although it is not a "balance" discharger, all 6 cells are still fairly close and then at home, I finish them off with a balanced storage charge.

I believe this is the correct statement. Consider putting two parallel batteries of the same size, C rating into a plane. Except for having to carry the extra weight, that plane should run for twice as long at the same throttle setting. If all you did was to run the throttle on the ground at mid-throttle (with some wind going into the intakes, it should run twice as long with two batteries as it did with one since the weight doesn't come into play when it just sits there. I guess you could do the same comparison when flying it although maintaining the exact same throttle for both flights and coming down with the exact same % left is difficult. Install two bats, but only hook up one, go fly. Next flight, replace the depleted battery, but now hook them both up and go fly. You'll likely double the flight time.

Just tested the parallel discharging method. Works just fine. Cells are fairly balanced after the cycle (this is where i was worried about).
Yes it did take double the time if you have 2 batts in parallel. Triple the time if you have 3.

The discharger gets the job down. Bluetooth connection could fail anytime though (once the bluetooth connection failed. the discharger WILL NOT CUT OFF. It will continue to discharge until unconnected). Give it some time to response after you hit start. Make sure it has the firmware updated.

I did more testing regarding the Bluetooth connection issue related to this discharger. Conclusion: It is not stable enough to leave it working on itown. The best if you calculate the time needed to discharge your batts. And set a timer on your phone.

[Twowingtj]

Mine is assembled and ready to go. Just waiting for the end of "Indian Winter" here in the northeast.

I've ordered the S.H.I.E.L.D. themed graphics from Callie. A red strobe/anticollision light was added to the top of the fuselage. I also added the nose gear brace from Wildvortex.

I had to go with a 6000mah battery to get the CG without adding dead weight.

[MeyerVW]

I get it now. They do not pick batteries based on the performance solely. Its also based on weight to get the aircraft to balance. You dont need the 6000 battery for performance you need it to balance the model. So by saying it can run on a 4000 to 6000 is true it just will not balance without some help. Now that I think about how they say it in the MotionRC videos it makes more sense. They should just say that

[Enzo_K]

I get it now. They do not pick batteries based on the performance solely. Its also based on weight to get the aircraft to balance. You dont need the 6000 battery for performance you need it to balance the model. So by saying it can run on a 4000 to 6000 is true it just will not balance without some help. Now that I think about how they say it in the MotionRC videos it makes more sense. They should just say that

I think there are some high C rating 4000 packs out there. Weight over 700g.

The performance thing about batteries is just a myth. Mostly caused by the false labeling from battery manufacturers. Theoretically, a 4000 40C pack surpasses what this power system needs. 4Ax40C=160A > 140A. But in reality, most 40C pack labeled by the manufacturer is only 25-35C. So, if you are not lucky, ur pack could be sitting on the lower end of that real C rating range. And a 25C 4000 pack doesn't have what this power system needs.

That being said, if you want to know more about the real C rating of batteries. Just Plane Crazy from Youtube has a video explaining it.

[GliderGuy]

Related to battery weight / CG discussion….
Might help to run a CG a bit farther back than the mark….read on.

Edit: To clarify - All flights to date have been with the CG on the wing mark…wheels down…right side up. Next flight will be with added weight in the tail.

Flying from a new place/narrow isolated county road…no traffic at all!

Last planned flight, she got into a crow hop and got a wing down into the roadside grass. This spun her into a low embankment (go figure)…nose first…straight into the embankment…BAM! She bounced straight back onto the road and landed perfectly level on the wheels.

Damage = crushed nose, broken nose gear door mounts, and a few paint creases further back along the sides. Had to “lengthen” the battery cover a tiny bit during the repair.

She is ONE TOUGH BIRD!

Flush-embedded carbon strips and epoxy to “fix” the crushed soft nose foam and hold it in place, filled, sanded, paint, and used Bondic UV plastic to repair/rebuild the broken gear door mounts**.

AND added a little weight to the underside of the motor mount “wings” as an experiment to reduce the crow hop that she’s done a few times.

She’s ready to go! Not perfect if you look really close, but I’m happy with the way it came out considering just how badly the nose was damaged.
Pilot added, too!

**The hinge holes in the fuselage completely tore open. The gear door hinges were not damaged. The hinge holes are THIN plastic. I added Bondic over the area where the holes were supposed to be, then drilled and shaped the Bondic. Took a couple of times to get it right (more Bondic), but it worked great!

-GG

[xviper]

Battery C ratings on almost all brands of batteries CANNOT be believed. As for a battery "surpassing" a plane's power system needs? My philosophy is to buy the highest C rated LiPo I can justifiably afford. A plane can function with more C but can't perform well with under C. If you want to see real world tests on all types of batteries, look here. The one rare brand that closely approximates it's stated C to real world numbers is SMC. Imagine peoples' surprise when their very expensive Spektrum 100C smart batteries only pushes out 25C. "But they're so light and I get telemetry". OK, if that floats your boat (or plane).
https://www.rcgroups.com/forums/show...st-Comparisons

[MeyerVW]

The C rating is a joke with no actual standard in place. We went over this with my AL37 and my Spektrum 6s 5000Mah 100c batteries. I know this now but its too late. I had to add a lot of weight to my OV-10. I used a 3000mah battery and get 10 min flight times. Works great. So light in weight I had to add over 3oz of weight to the nose. So I think a big issue with recommendations is the battery weight to balance the aircraft without adding weight. Maybe we can work that into the build people do

[xviper]

The C rating is a joke with no actual standard in place. We went over this with my AL37 and my Spektrum 6s 5000Mah 100c batteries. I know this now but its too late. I had to add a lot of weight to my OV-10. I used a 3000mah battery and get 10 min flight times. Works great. So light in weight I had to add over 3oz of weight to the nose. So I think a big issue with recommendations is the battery weight to balance the aircraft without adding weight. Maybe we can work that into the build people do

It is also entirely possible that when Freewing/MotionRC (or anyone for that matter) states a battery range for any given application, they are talking about the batteries that they customarily sell - in this case, Admiral. Admiral, like many of the other mid to top tier LiPos tend to be on the heavy side for their given mah rating and I've always considered that "more weight, more stuff inside, more performance" but then along comes SMC and blows that out of the water. When I decide to buy a LiPo, I always look at those real world testing charts first, then I look at the weight and dimensions of the battery, price, etc. I'll buy more mah if the brand has tested well, based on weight so the plane can be balanced without adding useless lead. Some of the latest planes are quite large with accompanying large battery compartments. I've been buying larger batteries to extend the flight times a wee bit, although this PJ can fly for a lot of time per mah of battery.
In a world where manufacturers exaggerate their claims and oft-times give bare faced lies to sell product, all the calculations in the world are meaningless, except for seeing the harsh reality of how the world actually works.

[MeyerVW]

Yea, looking at battery dimensions is not something I have really thought about but there is a big variety of batteries and weights. Of course Motion uses their own batteries with their aircraft. I just didn't realized there was a big difference in the weight between the manufactures. I now look at that chart as well. Its great info.

[xviper]

Now that I'm starting to get into 8s upgrades for a few of my planes, dimensions of batteries is important as I need to know if the total width/height of 2 batteries (usually either a 6000mah, 2s + 6000mah, 6s or 2 X 5000mah, 4s in series) will fit in the battery compartment. Weight also becomes a factor. Even for the PJ, I'm considering going with a couple of 6000mah, 3s in series, so it's good to know the combined width or height to see how they best fit into the battery bay.

In keeping on topic, when it comes to numbers, we've seen how the stated specs of EDF units don't always tell the whole picture. As many have noticed, especially those who own both the PJ and the Xfly of the Bizjet, the Freewing appears to be significantly faster, while both being able to fly for similar times at any given throttle usage. Both manufacturers state similar specs (including static thrust) for their fans, yet those numbers don't tell all. Is the performance of the PJ much better due to the design of the nacelles and/or the placement of the EDFs therein or is one manufacturer over-stating the performance of their product?
Then, getting back to the battery topic, is the performance difference due to the use of low level LiPos in the Xfly and the use of top tier LiPos in the Freewing? I tend to not see this as being the case as Mshagg from OZ, was one of the first to notice that his Xfly "seemed" slow and I doubt he uses garbage batteries, but who knows. I have personal experience that in a performance jet (Freewing A-10), a top tier battery performs "eye poppingly" better than a lesser battery - both in punch and in flight times.

[Enzo_K]

Battery C ratings on almost all brands of batteries CANNOT be believed. As for a battery "surpassing" a plane's power system needs? My philosophy is to buy the highest C rated LiPo I can justifiably afford. A plane can function with more C but can't perform well with under C. If you want to see real world tests on all types of batteries, look here. The one rare brand that closely approximates it's stated C to real world numbers is SMC. Imagine peoples' surprise when their very expensive Spektrum 100C smart batteries only pushes out 25C. "But they're so light and I get telemetry". OK, if that floats your boat (or plane).
https://www.rcgroups.com/forums/show...st-Comparisons

Since you have the testing chart. Just get the correct C rating you need for your plane's power unit. Going for the best C rating one can afford? A 70mm EDF will never need a 4000mah 100C pack. Only put more weight on the plane. It is reasonable to go over what it needs for 20%-25% for redundancy. As connectors, wires are not superconductors, they all consume power.

A little more experience sharing. since we are talking about Batts. These are all 6S packs.

520-580 grams. 4000mah class lipos are what I fly on my 70mm (twin 64mm) class jets. The lightest 4000mah class lipo I found so far (somewhat cheap. You can use "BATTSAVE" when you buy 2 or more for 10% off). Hobbystar 4200mah 40C packs Lipos at RCjuice, weighs only 520g. I have a dozen of them. Had one came with a bad cell (just let them know they will get you refunded for store credits). They are not the best performance pack. The real C rating is probably lower than 40C, maybe 30-35C. But they get the job done (most 70mm class jets will never draw over 80A, so I only need 20C for it). Flew 6 minutes on my 70mm Viper once did 14 touch&gos.

640-700 grams. 5000mah class is where things get awkward for me. They are too big for my 70mm class jets, yet too little flight time for 80mm class jets for my taste. SMC 5300mah 40C packs are what I use for now. However, I found 5000mah packs are great for your larger prop planes, like the 1.5m fw190, and 2m Draco.

820-850 grams. 6000mah class is what I use the most for all my 80mm (twin 70mm, & 90mm) class jets. I have 6 HRB 6000 50C packs. They are the cheapest yet decent pack you can get. I also have some SMC 6200mah 40C packs. This is one of the best if not the best performance pack out there. But they are not cheap. Another close racer is Admiral 6000mah 50C pro.

910 & above grams. 8000mah & above. These big bricks are only good for some big 90mm jets and Twin 70mm jets. I have 4 SMC 8100mah 20C packs at 910 grams. For my SU30, T45, PJ50, F100. Surprisingly, The E-flite F16 with full ordnance will also fly this 8100 pack. I can zoom around with full throttle for 5-6m with this pack in the F16. It will also fit the Freewing L-39, but I've yet to test it.


Note: the weight range is based on my knowledge of what that class of Lipo should be, considering the application, and SMC packs as a refference. For example, you can use a high C rating 4000mah pack weights 680g in a 70mm jet.

Will it work? Yes, as long as you get the CG right. But it is an over-kill for most 70mm jets. Which means you are carrying dead weight, in exchange of really marginal performance and flight time increase.

Will it give you longer flight time? Yes, but it marginal if you compared it with a similar 5000 pack with about the same weight.

Will it give you better performance? Yes, the C rating is what dictates the performance if capacity& weight stays the same. No, as the C rating increases, the weight goes up too.

So, again, calculate what your power unit needs. Weighs out the benefits and drawbacks yourself. If your 70mm jet needs 130A when full throttle? Sure, put at least a 60C 4000pack in it. If your 70mm jets only draw 70A maximum? Dont waste money on a 60C 4000 pack. Coz the drawback (dead-weight) will definitely outweighs the benefit (performance increased).