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

[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.

[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".

[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]

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.

[mshagg]

Based on the CAD work in the live stream i was picturing a solution where you simply swap in the lower part of the strut from something like an me262 oleo. Just need to find something that fits in the upper half of the strut and has appropriate clearances. Perhaps the wheel trucks can be removed completely and swap in a more conventional axle.

The B2 struts do look fairly robust so some mesure, fit and testing would be needed. https://www.motionrc.com/products/fr...085#hash-tab-5

[Aros]

Has anyone had luck flying off of grass? My club only has a grass runway and my B-2 arrives tomorrow. I am wondering if i should just do a return right away

It really depends on the shape and shortness of your grass. A golf green? Sure! It will take off on that but let's be honest, most clubs don't have golf green short and manicured grass on that level. These wheels and struts are small-ish...You are asking a lot to overcome that friction even on a decently manicured grass runway of an inch or two. I never once looked at this model as grass friendly. This screams paved runway. Now ridgerunner has some great advice. Raise the nose, aka AOA and you could find success.

[ridgerunner]

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.

[osuzoo08]

Has anyone had luck flying off of grass? My club only has a grass runway and my B-2 arrives tomorrow. I am wondering if i should just do a return right away

[xviper]

Doing some quick measurements, it looks like the largest wheel you could fit in the stock bay would be around 2.5” diameter. Of course, you’d either need to swap struts, or reconfigure the stock struts to grip a single axle instead of the bogie arrangement.

I think someone mentioned just swapping in a complete set of struts/tires from another plane. Perhaps known trailing links that have worked well on other planes.

[GliderGuy]

It FITS!

You can see how ramekin cups (P-38 wheels on top shelf) do a great job holding wheels. Then I use mini-bungees secure the wheels into the cups.

Ramekin cups fit large MiG wheels, too. WalMart has them. Glue them down with RTV silicon rubber. Then you can simply twist them off should you need to haul something. Then re-glue.

Look closely on either side of the B-2’s right main. The mains won’t fit ramekin cups I have. You will see a black clip on either side of the right main. I will run a mini-bungee from clip-to-clip across the main to secure it.

One mini-bungee wraps around the base of the nose gear’s ramekin. Then a second mini-bungee clips to the base bungee goes across the nose wheel and clips to the base bungee’s opposite side.

Secure a main and the nose….you’re done.

As a final touch, I used the shipping crate’s plywood planks to bridge the truck bed depressions. Now, the main gear trucks sit level on the plywood bridges and are under considerably less stress.

Someone suggested keeping the crate’s nice plywood. Bless that person!

For those with nicely carpeted beds, use Velcro to secure the ramekin cups to the carpet.

Now if only the wind would stop blowing!!!!

-GG

[F106DeltaDart]

Re: larger single wheel. Those who have this model would be the best ones to comment on this. Take a look at the size of the wheel wells. The way the main wheels are angled, they take up a lot of space and those wheel wells appear to be quite large. I think a fairly large singe wheeled strut could work in there. As for the nose wheel, that might be a limiting factor as the well doesn't look any bigger than any of the other double wheeled nose gears I have (eg. AL-37, PJ50 and assorted military jets).

Doing some quick measurements, it looks like the largest wheel you could fit in the stock bay would be around 2.5” diameter. Of course, you’d either need to swap struts, or reconfigure the stock struts to grip a single axle instead of the bogie arrangement.

[xviper]

Re: larger single wheel. Those who have this model would be the best ones to comment on this. Take a look at the size of the wheel wells. The way the main wheels are angled, they take up a lot of space and those wheel wells appear to be quite large. I think a fairly large singe wheeled strut could work in there. As for the nose wheel, that might be a limiting factor as the well doesn't look any bigger than any of the other double wheeled nose gears I have (eg. AL-37, PJ50 and assorted military jets).

[F106DeltaDart]

Is it possible to fit larger wheels for grass ops? I remember alpha showed some CAD of larger wheels but not sure if there is space in the wheel well.

Alpha was using a twist and turn retract (like the Corsair or MiG 29 mains) to fit the larger wheel in the CAD drawings. If you look at the front side of the gear bay, you can actually see the molded panel lines marking where the bay would need to be expanded to fit this larger wheel. So yes, should be possible but will take some alternate retracts and some foam cutting.

[Gilatrout]

Really sry, but that's probably the WORST advice I read in a while

I have 30 planes equipped with a gyro on my Spektrum and Frsky radio's with the gain always on the same rotary knob. Each of my planes has a number behind the model name eg. A-4 Skyhawk (3) or Mirage (5). The number corresponds to the gain I need for that plane, like on an analog wristwatch: 3 o'clock on the Rknob for my Skyhawk and 5 o'clock for my Mirage. On a Spektrum tx you can even set a pre flight check for that.

Most gyro users will tell you to use an Rknob for the gyro gain adjustment because it's easiest to use it during your flight.

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.

[Aros]

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.

[Gravythe clown]

Thanks Icarus, That was exactly what I was looking for, I use Frsky so -100 - +100 = 0-100% gain, but you got extra by going to -150 - +150? or was -150 - +150 + 0-100%?

As far as the gain value I use Global values in the model setup and use that as the weight in the the input (Gain). I then use a special function to have a spare trim up and down (I use throttle trim as I don't use because I fly electric only) to add to or subtract to the GV value. I started using this with my helicopters and have since carried it over to the S8/6R receivers.
That way the values is always locked in my model setup and still adjustable relatively easy. Also if I use flight modes I can have and adj gain per mode. Like in my Mirage, I have normal (For fast = low gain) Mid (landings = slightly higher gains) and stunt ( slow High alpha stuff = little more high gains). I can use trim to adj each mode separately and not affect the other modes.
I can't see using anything like all that though for this model, I really don't plan on flying her like the guy in that video making her wings flap. but it would be nice to be able to make minor gain adj if needed while flying.

Thanks again for the info

Gravy

[Gsky]

Is it possible to fit larger wheels for grass ops? I remember alpha showed some CAD of larger wheels but not sure if there is space in the wheel well.

[xviper]

I could also increase the gain further than the stock gain and noticed a lot more gyro compensation of all surfaces. In fact I raised the gain A LOT so that I could comfortably check if the elevator surface gyro movement was going in the right direction. With the stock very small elevator gain the gyro barely moved the elevator surfaces.

On a Spektrum tx just set the travel for the channel that controls the gain to 150 in both directions.

I thought as much but couldn't say for sure as I've not done this yet on any master gain. By going 150 on the travel, do you think you were able to increase the stock gains by 50%?

[T-CAT]

Realistically having remote gain is mostly used during tuning. Once you have found the ideal setting you bake that into the gyro proper and don't use the remote dial after.

Agreed. Once done in that manner, that provides less chance of accidentally touching the dial and altering the gains without intending to do so.

[mshagg]

Realistically having remote gain is mostly used during tuning. Once you have found the ideal setting you bake that into the gyro proper and don't use the remote dial after.