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

[Icarus the 2nd]

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.

[Icarus the 2nd]

So you have a system that works for you. It doesn't change the fact that with each flight you are only approximating the gains from the last time you flew.

Your workaround is a lot of work. Renaming the plane, setting startup warnings and whatever else. Far better advice is to use the digital trim and be done.

But hey, you be you.

in my experience my 'system' (the renaming is just once and I don't use startup warnings) is more than close enough, you won't even notice a few percentages difference

to each his own method I fully agree, that's why I reacted on your post where you used rather hard words like 'should NEVER'


I will give your method a try though, ppl are here to learn from each other

[Icarus the 2nd]

In addition to the confusion some were having about the single wire (AER) connectors where I was going to be adding a section to clarify that, if anyone would care to offer up any other vital bit of information (perhaps Icarus' great insight) please send me the verbiage/breakdown and I will be happy to add that to the online manual as well.

I found Xviper's wording really good:

Remember the confusion with those colored single wire leads when connecting stuff to the gyro? Regardless of color, those single wires are ALL "signal" wires. They go into the signal pin of those 3-pin ports. This is the same for the master gain lead. You hook up ONLY the "gain" pin on the gyro to the signal pin on the empty RX port. In this instance, stop thinking in terms of "polarity". Forget about the color of the wire. Also, the other pins on the "gain" port of the gyro are for something else. They are NOT power and ground pins. If all you're doing is using the master gain, eliminate the other two wires. It has become obvious that some folks haven't gotten this concept and "It doesn't work".

[Radar-Guy]

I said it before and I'll say it again...
This plane has a light wing loading with plenty of thrust from the twin EDFs and should have no problem quickly lifting off pavement or grass within a relatively short distance. The gear mechanisms are just fine the way they are. Its the wing's lack of sufficient positive AOA when sitting on the gear and rushing down the runway that appears to be the root cause of the problem. The failed grass launch videos make it appear that it may actually be generating negative lift as it speeds up pinning it down and preventing it from getting up to speed. A simple solution is to simply give it a bit more positive AOA by raising the nose a wee bit. This way, it will generate more lift as it picks up speed and allow the load on the gear (and its drag) to quickly decrease. Note that the CG position has nothing to do with this simple geometry issue - its all about Angle of Attack when sitting on the gear. Once again, IMHO.

Thanks, a valid point. This is a problem that I‘ve encountered with quite some Freewing models at my field. In some cases it was sufficient to reduce the travel of the nose oleo by using a simple cable tie, others needed more elaborate mods. What I saw yesterday was different. It was already obvious when taxiing at slow speeds, the main gear wheels were having a hard time on that kind of surfaces. It‘s not the usual smooth movement, the main gear trucks show a kind of bucking. I‘ve also noted that the nose oleo seems to be stiffer, i.e. I didn’t see the front „diving in“ as with a couple of other planes.

Testing will continue, I‘ve got a couple of different wheels and struts here.

[Radar-Guy]

Some other member of the group pointed me to this. It‘s all about „your grass“.

https://www.facebook.com/842573663/videos/pcb.1172717290209850/480807000491629

[xviper]

I found Xviper's wording really good:

Remember the confusion with those colored single wire leads when connecting stuff to the gyro? Regardless of color, those single wires are ALL "signal" wires. They go into the signal pin of those 3-pin ports. This is the same for the master gain lead. You hook up ONLY the "gain" pin on the gyro to the signal pin on the empty RX port. In this instance, stop thinking in terms of "polarity". Forget about the color of the wire. Also, the other pins on the "gain" port of the gyro are for something else. They are NOT power and ground pins. If all you're doing is using the master gain, eliminate the other two wires. It has become obvious that some folks haven't gotten this concept and "It doesn't work".

Thanks for the endorsement. I didn’t respond to Aros’s request because he asked for you directly. These single wire leads first came to my attention when I started installing Return To Home devices like the Bigaole. I thought it was peculiar that wire colors didn’t coincide with “polarity” but I followed the instructions and it all worked. Then comes along HobbyEagle’s newer gyros and they did the same thing. Now, we see Freewing’s new gyro is the very same. I only caution people about polarity now IF it involves servos. I think the industry should have standardized the wire color for these gyro applications by making them white or white with stripes.

[xviper]

Some other member of the group pointed me to this. It‘s all about „your grass“.

https://www.facebook.com/842573663/v...80807000491629

That video clearly showed (at least to me) that the ground speed on the grass was very robust compared to the failed take off videos. All grass fields are not created equal OR could it be that the power was down in those planes that failed to “launch”? Were the throttles calibrated properly? Where was the throttle trim? Unless told otherwise by the plane’s manual, I put the trim as far down as it’ll go before calibrating, thereby getting a little extra throttle “expansion” (I don’t know what else to call it). Did those people try to increase the throttle travel at the top end, maybe to 110% or 120%? I can’t say if that would have made any difference - just grasping at straws. Consider HV LiPos? I just got a couple to experiment with to see if any given jet will produce just a little more punch.

[Radar-Guy]

That video clearly showed (at least to me) that the ground speed on the grass was very robust compared to the failed take off videos. All grass fields are not created equal OR could it be that the power was down in those planes that failed to “launch”? Were the throttles calibrated properly? Wherwas the throttle trim? Unless told otherwise by the plane’s manual, I put the trim as far down as it’ll go before calibrating, thereby getting a little extra throttle “expansion” (I don’t know what else to call it). Did those people try to increase the throttle travel at the top end, maybe to 110% or 120%? I can’t say if that would have made any difference - just grasping at straws. Consider HV LiPos? I just got a couple to experiment with to see if any given jet will produce just a little more punch.

I used a well maintained battery, IR values in the 4,x range. Both ESCs were calibrated individually. Onboard telemetry (real time display on TX) showed peak value of slightly above 100 A.The Amp draw stabilised at around 90 A, no unusual sag of Voltage. That‘s close to 500W per kg and should be enough.
I will mount larger wheels (single ones on mains) and check how much that will reduce drag. If that improves speed during the T/O run, I‘ll look into the AoA aspect.

[kallend]

Thanks for the endorsement. I didn’t respond to Aros’s request because he asked for you directly. These single wire leads first came to my attention when I started installing Return To Home devices like the Bigaole. I thought it was peculiar that wire colors didn’t coincide with “polarity” but I followed the instructions and it all worked. Then comes along HobbyEagle’s newer gyros and they did the same thing. Now, we see Freewing’s new gyro is the very same. I only caution people about polarity now IF it involves servos. I think the industry should have standardized the wire color for these gyro applications by making them white or white with stripes.

All white would make it hard to identify which wire is which in the mess of wires that seem to inhabit my models. White with different colored stripes for the different functions would be OK. Personally I have never had any trouble with the current scheme and I have a bunch of HE gyros. But then I am a compulsive reader of manuals.

[kallend]

B. On Spectrum, the rotary switch should NEVER be used for gains. .

Rubbish.

[Radar-Guy]

I didn't like the fiddling with rulers while setting up the control surfaces, so two gauges were created and printed. +/- 25mm for the rudders, 8mm Up trim for the inboard control surfaces measured at wing bottom. In case someone is interested in the STL files, I'll put them on cults3d. Just let me know.

[mshagg]

100A feels a bit low for twin 70mm? You could probably get a bit more out of it by bumping up the timing of the ESCs. Given the intended flight envelope it would only really be used in TOGA scenarios.

[Icarus the 2nd]

100A feels a bit low for twin 70mm? You could probably get a bit more out of it by bumping up the timing of the ESCs. Given the intended flight envelope it would only really be used in TOGA scenarios.

it has the power setup of the PJ-50 and 2 x 60A ESCs, 100-105A numbers are normal

[crxmanpat]

Some other member of the group pointed me to this. It‘s all about „your grass“.

https://www.facebook.com/842573663/v...80807000491629

I asked Danny about his grass field. He is in Georgia and they have hard red clay under the grass. My field is on top of an old land fill and the ground is very sandy. His plane took off with ease, whereas mine bogged down and would not reach VR. So, grass ops are possible, but it really depends on the ground underneath the grass, not just the type of grass itself.

[Icarus the 2nd]

I asked Danny about his grass field. He is in Georgia and they have hard red clay under the grass. My field is on top of an old land fill and the ground is very sandy. He plane took off with ease, whereas mine bogged down and would not reach VR. So, grass ops are possible, but it really depends on the ground underneath the grass, not just the type of grass itself.

good info Pat, thanks a lot

my belgian grass is a lot like Radar-Guy's rwy

[Radar-Guy]

I asked Danny about his grass field. He is in Georgia and they have hard red clay under the grass. My field is on top of an old land fill and the ground is very sandy. His plane took off with ease, whereas mine bogged down and would not reach VR. So, grass ops are possible, but it really depends on the ground underneath the grass, not just the type of grass itself.

Thanks, Pat. You‘re right.
First mod is taking shape. Single FW T-45 main wheel (60mm) plus a „Frankenstrut“ (T-45 V2 Upper section plus Stinger lower section). Gear door is not entirely closing (2mm), but that‘s an easy fix for later.

[RudyD54]

I didn't like the fiddling with rulers while setting up the control surfaces, so two gauges were created and printed. +/- 25mm for the rudders, 8mm Up trim for the inboard control surfaces measured at wing bottom. In case someone is interested in the STL files, I'll put them on cults3d. Just let me know.

Love the idea. I’d be interested if you post them.

[kallend]

I didn't like the fiddling with rulers while setting up the control surfaces, so two gauges were created and printed. +/- 25mm for the rudders, 8mm Up trim for the inboard control surfaces measured at wing bottom. In case someone is interested in the STL files, I'll put them on cults3d. Just let me know.

Nice idea. A pity Freewing didn't include something like this in the kit.

[GliderGuy]

Potential “upgrade” offering…the “mains for grass operations” which could be offered on the MRC webpage. Would be handy to have.

Radar-Guy / Great idea - measuring tools

-GG

[ridgerunner]

... if anyone would care to offer up any other vital bit of information (perhaps Icarus' great insight) please send me the verbiage/breakdown and I will be happy to add that to the online manual as well.

A picture tells a thousand words... (e.g. this one from the manual of the very similar HobbyEagle A3S3 Gyro is very clear)