Official Freewing B-2 Spirit Bomber 86" Twin 70mm EDF Jet

[SanExup]

Radar-Guy I saw you are using 50mm for the front, what retract and wheel size are you using for the mains?

[Hugh Wiedman]

Thanks guys! The IR values were measured with a Junsi 4010 charger and my Lipos with such or lower value are powering my planes just fine. The outside temperature was considered as well, we had 20 deg C.
About the voltage: Who is using onboard telemetry or logging? You will NEVER get 4,2 V/cell under "standard EDF loads". It also of not much value to marvel at peak power, which was available for a few seconds. Have a look at performance charts published by serious EDF manufacturers like Wemotec or Ejets/Jetfan, where "stabilised" voltages during their testing was around 3,7V/cell. This is also the reason for the fantastic thrust values for fans from China. Power a fan unit with a steady 25,2V power supply and WOW!!!

I didn't fit a logger yesterday, just a real-time module. I will add one next time. Here is an example of a logged flight. Single FMS 70mm EDF, 6s, 3060-1900 kV, RT Lipo.
Red graph shows current, blue one Voltage

@ Hugh: Since you were involved in battery testing, could you show me one of your in-flight recordings? I'd love to replace my rubber bands!

I hear you, good point, although I will say that I won't use a battery with individual cell IR over 3. The SMC's are all in the 1.5-1.8 range and my "worst batteries" the HRB's/Roaring Tops/Admirals are in the 2-3 range (never use them anymore). I've not left the GT power meter hooked up in flight and yes, as the voltage drops, so does the Ah/Watts, as I've also tested them on the bench at 50% charge, but with a decent battery, it is not dropping down in the 90 Ah range. I'm no expert on EDF's, but I can tell you the the twin 70mm E-Flight fans EF2860-1850 Kv inrunners that came stock in the SU-30 were horrible fans and 1/2 the time I could not get it off grass. A fully charged 6000 still produced 120Ah and about 2800Watts, and at 50% charge it was 107 Ah 2400 Watts. I know the FW fans in the B2 are much better than those and top end your at 100 Ah and probably 2500 watts. The 70mm FMS fans together in the SU-30, 151 Ah/3700 watts, and at 50% charge 138 Ah/3100 watts. If you're only pulling 100Ah on a fully charged battery with those fans, somethings not right. Bench testing is one thing, only a place to start at. Since I fly off grass, the only real indicator is ground speed on take-off and there the bench testing has confirmed actual in-flight results.

I'll get a power draw reading on Monday of the stock B2 fans with an SMC 5300 and let you know what we're getting as we're about to find out if it will get off our grass runway.

[Radar-Guy]

Radar-Guy I saw you are using 50mm for the front, what retract and wheel size are you using for the mains?

https://www.hobbysquawk.com/forum/rc-airplanes/rc-military-jets/341524-official-freewing-b-2-spirit-bomber-86-twin-70mm-edf-jet?p=342958#post342958

[Radar-Guy]

…
I'll get a power draw reading on Monday of the stock B2 fans with an SMC 5300 and let you know what we're getting as we're about to find out if it will get off our grass runway.

Thanks, Hugh! Looking forward to it. Perhaps my charger gives different results than your measuring device. I‘ve got quite some Lipos here and these are well maintained, but I don‘t recall any of these showing values you mentioned. Bad cells usually show a value of > 8. But that should be discussed in depth somewhere else.

What do you think about this excerpt from the manual?

[RudyD54]

Hugh Wiedman

All this power talk got me curious. I just hooked mine up to a freshly charged SMC 5300 and my meter peaked at 121 and settled in around 116 amps at full throttle. We shall see on Monday if that’s enough to get off the grass.

[Hugh Wiedman]

Radar-Guy , I'm not trying to be argumentative, I'm just trying to figure out if there is another reason you could not get off grass other the the gear (obviously could be a combination of things) because I'm in the same boat. Rudy just tested his above and you can see the results he got and just from the numbers you had, especially the batteries at 4 or > IR value when both of us use batteries in the 1-1.5 range, something didn't seem right. And only pulling 100 amps stabilizing at 90 amps just sounded way too low. You can see he's at least 20-25% higher. Is there any way your ESC is just not functioning correctly or lost it's calibration?

[Amahoser]

Maidened the B-2 today and it was successful.... sort of...

Here's a video of the maiden a friend took.:

https://youtu.be/o4Dd3YcAHqQ

flight at Apollo XI in Van Nuys, CA. Long paved runway.

Maiden flight: lined up and gently applied power till full. Plane rose off the ground and my canopy blew off! Didn't check that the latch was secure apparrantly! Did a couple of laps then gear up. Flying very easy. Did a roll and it responded beautifully. Did some slow and fast passes. On the fast passes, I noticed the gyro wiggle people have complained about. I think the book rates are pretty spot on. Very responsive and the roll rate was very good. Inverted seems to hold with just a bit of down. Only very minor trim... just a couple of clicks on elevator and aileron. Let my 4 minute timer count down all the way. Then did a gear pass and brought her in. I was a bit nervous since I've seen a few maidens on YouTube where the plane came in fast and bounce. I came in on final, dropped the throttle all the way. Plane started to drop so I gave it a bit of throttle. I kept up elevator to slow the plane down. It came in nice and slow. Kept feeding up elevator and it touched down nice and slow. Easy plane to land. Lands more like a prop plane with a high lift wind than an edf. Lands like my hobbyking vampire with a bit more weight. Overall, very impressed. You know how with some planes, you fly it and it feels like it's on rails? You just say how good it flies? Well it's weird.... this plane isn't that... you feel that it doesn't track straight..... but it does.... you think it's not "on rails" when flying it, but it is.... not sure how to describe it but I assume it's the gyro doing it's thing. I normally do not fly with a gyro, especially on bigger planes.

Second "flight"
This time I'm feeling a bit more confident. Taxi out and everything feels good. Tried to take off and once power is applied, the steering is all over the place! I cannot get it to track straight. Checked and all the landing gears are tight.... don't understand it. I lined up again and it was still all over the place. Felt like I didn't have any noise steering authority. It was turning to the left. I was near full throttle in a turn and I felt that I was committed.... kept on the throttle and it was still in a slight turn. It finally rose off the ground but it was too late. Plane got some overgrown weeds and stopped. Damage was light. Only the removable wing sections showed some damage and a small chunk of foam came off. Took the plane back it the bench to check everything out.... landing gear still remained good... nothing seemed loose. I doubled checked everything I could. I even recalibrate the throttle (even though I did it before). Nothing seemed bad. Charged up another battery to try again... only things I can figure is there was a light crosswind. And possibly I needed to hold down elevator to keep the noise gear down to give it authority.

Third flight:

I did a high speed taxi test. Still veered but it was more controllable... lined up for a take off. This time I had a headwind... no crosswind. Took off nice and easy..... flew for a while. Did a few rolls and I sustained inverted. No problems. Next flight I'll try a stall turn... turned on the audio level gyro for the first time and it was dead on. I was worried as I couldn't find anywhere in the instructions a calibration setting but it flew great with the gyro in "safe" mode. Landed it (butter) and felt much better. Still don't fully understand my issues on my second attempt.


I did (as I do with all my planes) separate the rudder from the nose steering and have that on a different channel. I'll try an Assan steering gyro and see if that helps. Overall, very impressed with its flying abilities.

Jose

[Radar-Guy]

Radar-Guy , I'm not trying to be argumentative, I'm just trying to figure out if there is another reason you could not get off grass other the the gear (obviously could be a combination of things) because I'm in the same boat. Rudy just tested his above and you can see the results he got and just from the numbers you had, especially the batteries at 4 or > IR value when both of us use batteries in the 1-1.5 range, something didn't seem right. And only pulling 100 amps stabilizing at 90 amps just sounded way too low. You can see he's at least 20-25% higher. Is there any way your ESC is just not functioning correctly or lost it's calibration?

Neither am I. Saw Rudy numbers. I set up the ESCs as usual and my figures were in the same ballpark as the ones reported by Icarus. I will check some things here.

[xviper]

I did (as I do with all my planes) separate the rudder from the nose steering and have that on a different channel. I'll try an Assan steering gyro and see if that helps. Overall, very impressed with its flying abilities.

Mine will get the Assan steering gyro before it goes to the field. It's already waiting on the table for its new home. I've been very surprised by all the videos that this plane doesn't do the wandering minstrel thing. It's got such a short "wheel base", I would have expected it to wander all over the runway.

[mshagg]

If the box configuration has the steering and drag brakes y-d then the nose wheel would be benefiting from that very high gyro gain on the yaw axis.

[kallend]

I hear you, good point, although I will say that I won't use a battery with individual cell IR over 3. The SMC's are all in the 1.5-1.8 range and my "worst batteries" the HRB's/Roaring Tops/Admirals are in the 2-3 range (never use them anymore). I've not left the GT power meter hooked up in flight and yes, as the voltage drops, so does the Ah/Watts, as I've also tested them on the bench at 50% charge, but with a decent battery, it is not dropping down in the 90 Ah range. I'm no expert on EDF's, but I can tell you the the twin 70mm E-Flight fans EF2860-1850 Kv inrunners that came stock in the SU-30 were horrible fans and 1/2 the time I could not get it off grass. A fully charged 6000 still produced 120Ah and about 2800Watts, and at 50% charge it was 107 Ah 2400 Watts. I know the FW fans in the B2 are much better than those and top end your at 100 Ah and probably 2500 watts. The 70mm FMS fans together in the SU-30, 151 Ah/3700 watts, and at 50% charge 138 Ah/3100 watts. If you're only pulling 100Ah on a fully charged battery with those fans, somethings not right. Bench testing is one thing, only a place to start at. Since I fly off grass, the only real indicator is ground speed on take-off and there the bench testing has confirmed actual in-flight results.

I'll get a power draw reading on Monday of the stock B2 fans with an SMC 5300 and let you know what we're getting as we're about to find out if it will get off our grass runway.

Ah is the abbreviation for Ampere hours. A is the abbreviation for amps (amperes).

[MeyerVW]

Mine will get the Assan steering gyro before it goes to the field. It's already waiting on the table for its new home. I've been very surprised by all the videos that this plane doesn't do the wandering minstrel thing. It's got such a short "wheel base", I would have expected it to wander all over the runway.

I dont think you will need it unless you separate the steering from the rudders. I ground tested and the aircraft steers great at full throttle when the aircraft is set up correctly. I did not test to see if when the gear are down if the gyro also corrects the steering along with the rudders.

[xviper]

I dont think you will need it unless you separate the steering from the rudders. I ground tested and the aircraft steers great at full throttle when the aircraft is set up correctly. I did not test to see if when the gear are down if the gyro also corrects the steering along with the rudders.

I'm at a loss to explain why Amahoser's plane was wandering so bad. Is his an exception to the "norm" for this plane? Even though we see that the rudder gain is at 100%, I'm curious how this relates to the set gain in an Assan steering gyro. Perhaps 100% gain in an "air" rudder is meaningless for a steering wheel. I'm looking at the Pulsar gyro from X-Fly and it has a separate plug for the nose steering. If the setting for the air rudder was applicable for the nose steering, then why use a separate circuit? However, the Pulsar does recommend to start with 30% gain so perhaps 100% gain for the B-2's rudder may in fact, be enough for ground steering correction.
Anyway, I'll get to see first hand when my buddy maidens his what the ground handling looks like. Mine won't get here till after that happens (unless winter drags on).

[xviper]

That guy Pittxxxxxx made it work on the second power up with the HE programmer. However, I think he's a bit "odd", so who knows exactly what he did or saw.

I wish to correct some information. It was NOT Pittxxxxx that was able to make the HE programmer work but was another person whose post I have linked below. (I still think Pittxxxxx is "odd" but that's another story.)
https://www.rcgroups.com/forums/show...&postcount=695
It should be noted that she (I think it's a "she") was using an A3S2 programming card, so a big goes here.

[Gravythe clown]

So after all the videos, I decided on one mod before maiden, I agree the siting AOA is to flat. My last B2 had a little more upward nose AOA and she lifted her self off with no effort. I’m guess this may also be why for the addition up trim suggested. All the videos I’ve seen so far are pop ups.
so I too found some 10mm in my stock taller wheels and threw them on. Doors still close and now I can see a noticeable AOA as she sits.

I’m wanting to maiden her this weekend but looks like another high wind and possible rain. If I get dunked out I’ll spend the time building my Combat reaper. It’s been to long that I haven’t gotten up in the mess with the guys.

Gravy

[KevinMar]

This plane is sweeeet!

Maiden + 2 more flights today! I don't think this will be coming with me every time I go flying, but she sure is a special bird.

Maiden was uneventful. I forgot the vertical stabilizer at home, so I just used my field's ID badge (credit card) as the stabilizer, and it worked just fine. I chose my 3 oldest batteries for this bird because I know she's just meant to be a cruiser, and she did just fine.

I had some moderate winds with gusts, so sometimes the B-2 would become a bit more pitchy than expected (when in head wind), but I really didn't feel any bad tendencies in any of the 3 flights. Most interestingly was that I could not feel any yaw washout at all. Very solid flyer.

Landings weren't difficult, but they were different. Can't do a standard EDF jet glide slope with a flare. I found that bringing it over the runway nice and level with only a last inch flare (if any) was best. She sits down on her mains as they articulate, and then the nose touches down pretty quickly. Not difficult, just different.

Happy flying everybody!

[kallend]

I wish to correct some information. It was NOT Pittxxxxx that was able to make the HE programmer work but was another person whose post I have linked below. (I still think Pittxxxxx is "odd" but that's another story.)
https://www.rcgroups.com/forums/show...&postcount=695
It should be noted that she (I think it's a "she") was using an A3S2 programming card, so a big goes here.

The A3S2 card is not compatible with the A3S3 one. They even have different USB connectors so I'm not sure how the cable would work.

Anyhow, it could be that E52 is A3S2 based, I suppose, all the connection to the Rx are the same.

[ridgerunner]

Bigger diameter wheels
I too have a grass rwy and I suspected some take-off problems, so 2 days ago I looked at the front wheels. Those are 45mm diameter, you can easily change those with 55mm diameter (which I did already) there's plenty of space in the front gear bay to install even bigger wheels but more than 55mm will rub/bind them against the bottom of the wooden battery floor.

The wheels of the mains can be easily changed to 50mm diameter instead of the stock 45mm diameter.

I'd like to give it a try but our grass rwy won't be accessible untill mid next week.

With 55mm front wheels your raise the AoA by 5mm.

I am now confused - the B-2 spare parts page lists the main and nose gear wheels as 70mm.
So what are they - 45mm or 70mm? (I'm guessing that the MRC product pages for the gear diameter is incorrect, but I'd like to know for sure. My B-2 is scheduled to arrive tomorrow.) I'd like to order some equivalent style larger nose wheels that will easily fit into the nose gear compartment without any modifications. Note that I'll be having the nose gear steering servo on its own dedicated channel that will remain in a fixed centered position when the gear is retracted (it will be tied to the rudder stick with a LOT of expo and only steer when the gear is down).

[JamesonC]

I am now confused - the B-2 spare parts page lists the main and nose gear wheels as 70mm.
So what are they - 45mm or 70mm? (I'm guessing that the MRC product pages for the gear diameter is incorrect, but I'd like to know for sure. My B-2 is scheduled to arrive tomorrow.) I'd like to order some equivalent style larger nose wheels that will easily fit into the nose gear compartment without any modifications. Note that I'll be having the nose gear steering servo on its own dedicated channel that will remain in a fixed centered position when the gear is retracted (it will be tied to the rudder stick with a LOT of expo and only steer when the gear is down).

That is the description of the plane, not the part. Twin 70mm B-2 Spirit Bomber is in front of the part listed so you know what it fits. That is not the wheel measurement.

[crxmanpat]

I am now confused - the B-2 spare parts page lists the main and nose gear wheels as 70mm.
So what are they - 45mm or 70mm? (I'm guessing that the MRC product pages for the gear diameter is incorrect, but I'd like to know for sure. My B-2 is scheduled to arrive tomorrow.) I'd like to order some equivalent style larger nose wheels that will easily fit into the nose gear compartment without any modifications. Note that I'll be having the nose gear steering servo on its own dedicated channel that will remain in a fixed centered position when the gear is retracted (it will be tied to the rudder stick with a LOT of expo and only steer when the gear is down).

I think all wheels on the B-2 are 46mm.