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

[Enzo_K]

I'm with xviper when it comes to battery C, the higher the better, depending on the weight of course. That's why I now exclusively use the SMC 40C packs in all my EDF's. They give me more flight time and much better take-off and vertical than the actual 20C batteries like Roaring Top/Admiral Pros/HRB's etc. And just because a motor doesn't NEED a higher C, doesn't mean it doesn't give some advantages. Case in point, I now also use the SMC 6200 40C in my FW Spitfire and Corsair (and these don't really NEED a higher C battery), after using the Admiral Pro 6000, HRB 6000 and Roaring Top 6250. The SMC's give me longer flight times (12 minutes on the Spitfire and 10-11 minutes on the Corsair) then I used to get and when I punch it, it's got at least 20% more "giddy up" than any other battery I've tried, get's off grass like a carrier shot and goes vertical like a missile. So for me, proof is when I'm happy about how it flies! I've also seen both the FW and X-Fly Gulfstream (sorry for not using the non-copywritten call letters) fly using my SMC 6200's and frankly couldn't tell the difference in them, but then I wasn't the one at the sticks. But I'm a MRC guy through and through so the PJ50 would be my first choice any day of the week. IMO, at this level, batteries make the difference! Liperiors are great also, high C, but they are a bit heavier than SMC's. Climbing down from my "soap box" so I'll shut up now!

Yeah, That is also what I was trying to say. We have to say under the same weight, the higher the real C rating the better. I just did not want people to go for some the "highest" C rating just becoz they can afford it. They are either overpaying for a fake C rating. Or putting too much dead weight for a fake C rating.

SMC is definitely the best on the market. They actually specifically designed those packs to fit most EDF jets. And if you noticed, none of their True Spec Extreme Graphene V2 Flight packs has a C rating higher than 40. So, really, don't get some 100C 4000mah pack that costs $120. Or some 70C 4000pack weighs 150g heavier than a SMC 40C pack.

[Hugh Wiedman]

I'm with xviper when it comes to battery C, the higher the better, depending on the weight of course. That's why I now exclusively use the SMC 40C packs in all my EDF's. They give me more flight time and much better take-off and vertical than the actual 20C batteries like Roaring Top/Admiral Pros/HRB's etc. And just because a motor doesn't NEED a higher C, doesn't mean it doesn't give some advantages. Case in point, I now also use the SMC 6200 40C in my FW Spitfire and Corsair (and these don't really NEED a higher C battery), after using the Admiral Pro 6000, HRB 6000 and Roaring Top 6250. The SMC's give me longer flight times (12 minutes on the Spitfire and 10-11 minutes on the Corsair) then I used to get and when I punch it, it's got at least 20% more "giddy up" than any other battery I've tried, get's off grass like a carrier shot and goes vertical like a missile. So for me, proof is when I'm happy about how it flies! I've also seen both the FW and X-Fly Gulfstream (sorry for not using the non-copywritten call letters) fly using my SMC 6200's and frankly couldn't tell the difference in them, but then I wasn't the one at the sticks. But I'm a MRC guy through and through so the PJ50 would be my first choice any day of the week. IMO, at this level, batteries make the difference! Liperiors are great also, high C, but they are a bit heavier than SMC's. Climbing down from my "soap box" so I'll shut up now!

[GliderGuy]

The post-repair flights were uneventful. I’m still working on the twitchy aileron on final thing. I cranked the expo up to 50% the last several flights this evening. Getting better…not so twitchy on final when gusts hit her.

The added weight in the tail didn’t affect her characteristics. Based on experience, I “estimated” it was enough weight to move the CG back 5 mm, but maybe all I did was counter the added weight to the nose when doing the repair.

Tomorrow I will actually measure the CG location and report. Maybe it didn’t change after all.

The repair looks good in the strong sunlight. The glare helps to hide some of the imperfections of the repair.

The pilot looks good bathed in sunlight with his sunglasses and headset on.




-GG

[Enzo_K]

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.

You are right. Freewing carries 2 types of 5000 packs. admiral 5000 50c and admiral carbon 5100 70c. Most people call both of them 5000 packs, but one is 130+ grams heavier.

In general, I don't worry about the height and width. As long as you go with the recommended battery capacity range. The length is where CG could come into play. You may find 2 batteries weigh the same. But one might be 15mm longer than the other one.

For example. If you balanced your plane with the shorter batt at the very front/back of your battery bay. The same weight but longer batt won't fit. You will have to add some lead in the nose/tail to balance it.

So my advice is to choose a reputable brand from the beginning, and stick with it. Also divide your planes into size classes. Then you can use the same batt on the same class. Rather than having 3 different 5000 packs, and have to balance them on the same plane 3 times.

[Enzo_K]

Hi Enzo…All flights have been with the CG on the wing mark. Every single flight so far.

Hopefully, in about an hour the wind will calm enough to do some flights with the added weight in the tail. When I fly it next time, the CG will be about 5 mm aft of mark (Admiral 6000 up front).

Thanks…Took several days to get it good enough.

-GG

5mm aft the CG mark could be a lot of change on a high aspect ratio wing plane. I would just push the battery back by a half inch every time. Or maybe 1/4 inch every time. As the batt on the PJ50 is pretty far forward. And CG could be sensitive to any battery movement.

Good luck on the test flight! Looking forward to see the result.

[Enzo_K]

Like I said, buying the most C I can justifiably afford is MY opinion and is what I do. You do whatever you want. We've talked about this on this forum ad nauseum. Most people don't consult these charts and don't do your fancy-Dan calculations. I will continue to buy the way I see it. Like sporty cars. Who really needs a 700hp SUV? NOBODY, but man is it fun and it's NEVER enough.
And as I also already said about the PJ being faster. I don't care about what your calculations mean about wing loading and such. I said I didn't have a reason why the PJ is faster. All I care is that it is. In that sense, calculations mean nothing to me and you can slide rule this to death if you so desire. This hobby is for fun for me. I use what facts and information I need to have that fun. There comes a certain point when all the armchair guys just suck the fun right out of it. Some may be impressed by all the numbers. It just makes me roll my eyes and walk away. And once again, as on the other forum, I won't be posting on this subject with you again. It's very tiring to debate anything with someone who just has to have the last word and has to be prove they are right all the time. You are hereby given full blessings to have the last word and be right all you want.

A 700hp SUV might be fun. More dead weight in a plane is another story though. lol. It's more like a heavier 700hp engine in an SUV with a transmission that can only handle 20mhp.

I'm kinda lost here. You seem to be the one trying to figure out why the PJ is faster. You mentioned speed, specs, numbers all of that. I'm only here to give some numbers. If 30% difference in a wing area is to be ignored. And you think that is me trying to be the "right armchair guy". Fine? I prefer the "armchair aeronautical engineer" you called me on the other forum. lol

Again, numbers may not be fun for u. But it could help those who want to know why. Also, like I said on the other forum. I am just posting my numbers and thoughts here. Arent anybody forcing you to read/reply to it.

[xviper]

Like I said, buying the most C I can justifiably afford is MY opinion and is what I do. You do whatever you want. We've talked about this on this forum ad nauseum. Most people don't consult these charts and don't do your fancy-Dan calculations. I will continue to buy the way I see it. Like sporty cars. Who really needs a 700hp SUV? NOBODY, but man is it fun and it's NEVER enough.
And as I also already said about the PJ being faster. I don't care about what your calculations mean about wing loading and such. I said I didn't have a reason why the PJ is faster. All I care is that it is. In that sense, calculations mean nothing to me and you can slide rule this to death if you so desire. This hobby is for fun for me. I use what facts and information I need to have that fun. There comes a certain point when all the armchair guys just suck the fun right out of it. Some may be impressed by all the numbers. It just makes me roll my eyes and walk away. And once again, as on the other forum, I won't be posting on this subject with you again. It's very tiring to debate anything with someone who just has to have the last word and has to be prove they are right all the time. You are hereby given full blessings to have the last word and be right all you want.

[GliderGuy]

Hi Enzo…All flights have been with the CG on the wing mark. Every single flight so far.

Hopefully, in about an hour the wind will calm enough to do some flights with the added weight in the tail. When I fly it next time, the CG will be about 5 mm aft of mark (Admiral 6000 up front).

Thanks…Took several days to get it good enough.

-GG

[Enzo_K]

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

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

Have you been testing the aft CG? Or this flight you are talking is done with the aft CG? BTW, the repair looks great!

[Enzo_K]

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.

The wing area on the PJ50 is 33dm^2. While it is 43dm^2 on the J65. (that's 20% if not more drag) Pj50 has better design in nacelles, lower static EDF unit thrust on paper. Despite, the difference between their power units. Its pretty normal PJ50s can fly faster. Some prefer their airliner fly low and slow, some enjoy going fast.

I think both manufacturers are reputable brands so far. I don't think there is any intended overstating of any stats on any party. The end result difference is most likely due to the difference in design. In my opinion, The wing area difference probably plays a bigger part than those differences between their power units.

[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).

[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.

[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]

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]

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]

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

[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

[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.

[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

[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.