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

[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]

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!

[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

[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. :wave:

[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. :wave:

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.

[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]

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.

[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

[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" :cowboy: 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! :hugging: 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!

[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" :cowboy: 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! :hugging: 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.

[xviper]

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" :cowboy: 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!

Hugh, I've been meaning to ask you ............................ Have you used the SMCs long enough to get data on their duty cycles? When I started to buy high C LiPos, another thing that I noticed besides greater punch in all kinds of planes and longer flight times, was that they gave me more duty cycles than my early low C rated batteries. Where I used to get around 200 cycles on the low C bats, I was getting well beyond 300 cycles, some even approaching 400 cycles and still those batteries have yet to degrade (sag) early during a spirited flight. There's more advantages to high C LiPos than initially meets the eye.
BTW, I'm still yet to score some SMCs. That store in Canada only stocks certain SMC stock and they never seem to have any that I would like to have. They cater more to the RC car market.

[Hugh Wiedman]

Hugh, I've been meaning to ask you ............................ Have you used the SMCs long enough to get data on their duty cycles? When I started to buy high C LiPos, another thing that I noticed besides greater punch in all kinds of planes and longer flight times, was that they gave me more duty cycles than my early low C rated batteries. Where I used to get around 200 cycles on the low C bats, I was getting well beyond 300 cycles, some even approaching 400 cycles and still those batteries have yet to degrade (sag) early during a spirited flight. There's more advantages to high C LiPos than initially meets the eye.
BTW, I'm still yet to score some SMCs. That store in Canada only stocks certain SMC stock and they never seem to have any that I would like to have. They cater more to the RC car market.

That's a shame, I know you would really enjoy the 6200 in your Pj50 and your SU-30 (actually, in anything you put them in). I need to take a trip north some day and sneak a few across the boarder for you.

I haven't got enough duty cycles on them yet to make any meaningful conclusion. I have 16 of them and 8 of the 5300's and each is numbered so I don't use any one of them more than the others. In total, each has about 45 cycles (but don't really even log every flight) so it's too early to tell for sure. So far, I've tested each one continuously on the Progressive IR meter and with the GT power meter in certain aircrafts and none have shown any loss in any cell on IR/amps or power usage yet. I did test and record each cell on a chart I keep for all my batteries when I first got them to at least have a starting point and all are still the same as when first purchased. If I start seeing any degradation, I will definitely let you know. My main flying buddy, RudyD54 who first turned me on to these, has so far seen the same and he's got a lot more flights on them than I have. As I've said before, Danny is really customer service friendly and I think Rudy had an issue with one of his packs recently and Danny sent him a new one, sight unseen. When he came up with the 5300's, I told him I wanted at least 4 of their new design but he wouldn't send them to me until after a couple iterations of them that he was happy with and that passed his tests. When you send him an e-mail, he always answers within 6-12 hours, so he is definitely one of the good guys in this hobby!

[xviper]

Thanks, Hugh. Hehe, once you cross the border straight up from where you are, there's still nearly a whole country to cross to ship those things to me. One day, I'm going to bit the bullet and order some directly from Danny just to see what the process (cross border shipping) is like. My other "go to" brand (CHL) has set up a Canuck warehouse, so getting those is quite easy now. In fact, so many people at one of my clubs are impressed with them that they're setting up a group buy this spring.

[GliderGuy]

Background; Trying a new flying site / Narrow isolated county road with zero traffic / Slight dirt/grass embankment parallel to the road about 15 ft distant / Slight cross wind / Landed off center / Wing tip caught on grass / Spun the PJ50 into the embankment...nose first / BAM = Ouch = crushed nose and damaged gear door hinges.

As mentioned in my prior post #408, I added weight to the tail (under the engine mount wings) during the repair of the mashed nose. The intent was to experiment to determine whether or not the infrequent crow hop tendency (about 5 times in 100 landings) might be reduced; similarly to what moving the CG back on the A-10 accomplishes, in this regard.

Just measured the CG. Apparently, it is a good thing that I added the tail weight. She balances ever so slightly behind the CG mark...maybe 1 mm. I'd hoped to have moved it back farther, but more weight will need to be added to accomplish this. Maybe I will add more, maybe I won't. Still deciding. Perhaps I just need to improve my PJ50 landing technique (most probably).

Bottom line, it was a good thing that I did add the weight to the tail. Otherwise, the material added to the nose area for the repair would have made her slightly nose heavy.

Update: Logged flights = 104 total since new and 5 days of down time for the repair and uncooperative winds since the crash on 03/25. Uneventful post-repair flights were made on 3/31. Perhaps adding the pilot figure in the cockpit (photo in post #408) will improve my flying! She's one tough bird!

Back in the PJ50 saddle again. Post-repair photo in post #394.


-GG

[MeyerVW]

It was a very cross windy day. Flies pretty good. It gets tossed around but its controllable. It lands nicely with a few clicks of engine idle when landing I found. Some video of the flights.

[avanti127]

Got my windows cut out last night and the 3d portals installed. The plastic window were cutout yesterday and just need to be tinted. Then a repaint and install the windows, PJ will be ready for maiden soon.

[Gilatrout]

Got my windows cut out last night and the 3d portals installed. The plastic window were cutout yesterday and just need to be tinted. Then a repaint and install the windows, PJ will be ready for maiden soon.

Very nice. I was thinking about a slightly different approach for mine. I like yours better. Did you add any internal supports?

Tell me more about your jig. I could use something like that. Interested in sharing?

[avanti127]

Very nice. I was thinking about a slightly different approach for mine. I like yours better. Did you add any internal supports?

Tell me more about your jig. I could use something like that. Interested in sharing?

Sure no problem sharing. Do you have a 3d printer? It was really easy to do. The window portals are printed from PLA so it is stronger than the foam.... The JIG I made is to move from window to window. Pin them in the center of the first two window, cutout the one to the right, then move two the next by moving the jig that way everything stays in alignment. I used a #11 Xacto knife and gently traced around the jig, then went back and cut straight through. The foam came right out and my window portals pressed right in solid against the foam.

I can send you the files if you want to print everything out.

[Gilatrout]

Sure no problem sharing. Do you have a 3d printer? It was really easy to do. The window portals are printed from PLA so it is stronger than the foam.... The JIG I made is to move from window to window. Pin them in the center of the first two window, cutout the one to the right, then move two the next by moving the jig that way everything stays in alignment. I used a #11 Xacto knife and gently traced around the jig, then went back and cut straight through. The foam came right out and my window portals pressed right in solid against the foam.

I can send you the files if you want to print everything out.

Sure, I'd love to try your files. I'm pretty sure .stl files can be attached to thread messages.

I already copied your jig. ;)

Did you curve the window portals to match the diameter of the plane's fuselage?

Thanks

[avanti127]

Send me your email address and I will send the files.

yes the geometry is the same as the decals.