Official Skynetic Bison XT STOL Discussion Thread

[Warlox]

Is everyone locking out the leading edge slats? Are they not actually useful?

[Atrix]

Is everyone locking out the leading edge slats? Are they not actually useful?

I have them disabled, and it is not very clear to me what value they bring. I presume the idea is that they would enable even slower flight than what the flaps allow, but I don't recall anyone saying so explicitly.

Some have said that there is an ability to tune the amount of slats that are activated for a given amount of flap, but, mechanically, I don't know how that would work without a springed linkage to the slats (like nitro rc car throttle linkages). Otherwise in order to have zero slats at zero flaps, there would be a fixed ratio of slats to flaps.

[2much2do]

Is everyone locking out the leading edge slats? Are they not actually useful?

So here is a quick explanation of how slats are supposed to work:
https://www.boldmethod.com/learn-to-...t-lift-device/

The slats on the bison, don't open correctly, effectively the become leading edge spoilers I think, which is a problem.

So the slats are useful, and people report them working, but don't open them with the actuation as designed. You can read a lot more on this design in the RCG threads for the seagull shock cub

Also if you look at the Freewing T-45 that Motion sells, it has slats that at least look like they would work a champ.

[Atrix]

So the slats are useful, and people report them working, but don't open them with the actuation as designed.

Hmm, I don't completely follow. Slats, in general, are useful (see video), but are the "slats" (spoilers?) on the Bison, in their current actuation form, useful? And if so, for what? Slower flight? Different flight characteristics? Is it just that it's harder to fly and that provide extra challenge for experienced pilots?

[2much2do]

Hmm, I don't completely follow. Slats, in general, are useful (see video), but are the "slats" (spoilers?) on the Bison, in their current actuation form, useful? And if so, for what? Slower flight? Different flight characteristics? Is it just that it's harder to fly and that provide extra challenge for experienced pilots?

Fully closed they are placed well to be slats, they should not be "Opened" so most people are just fixing them in one position and not trying to use them as an actuatable surface.

[Gilatrout]

My kit came with 2 left wing struts.....they can't be built upside down...wtf

I even tried to flip one by re-tapping the plastic parts, the angles on the plastic do not fit with the bottom of the fuselage.

Did you get this resolved?

[2much2do]

Did you get this resolved?

I have a tracking number, but nothing in hand yet, I saw you had the same issue, they had me fill out their online trouble ticket, and then attach pictures. You have to keep bugging them to make them move it forward. There was something else they were supposed to do which they still have not done.

[Atrix]

Just an update from my weekend exploits with the Bison. We had an event at my local field, and I got some more eyes on the Bison from the crew of experienced pilots. Everyone was a bit flummoxed by the tail wheel and its tendency to not track very well (especially after some rudder input), making take off from the paved runway very tricky. There were a good number of failed take offs and ground loops and unfortunately the ends of my wings are bit beat up as a result. Once we switched to takeoffs in the grass, things improved quite a bit, but I am not entirely sure why, maybe less traction on the rear wheel meant less likely to be taken off course 🤷♂️

In any case, once I could take off with some regularity, I got through about 5 packs without too much trouble. In the air, I am still having to trim rudder, but other than that it was well behaved. I was doing low, slow passes all day with a few rolls and loops tossed in here and there. I have flaps mixed with elevator, but I have to tweak that a bit because I still pitch up on half flaps and pitch down on full flaps. Despite all the interesting challenges, I am still quite happy with the Bison and really enjoying it in the air (less on the ground).

Some things in the works. As you may have seen above, I am working on a springless tailwheel setup. I will report back how that goes this weekend. Also, I am designing 3D printable custom wing/aileron skids to help with my tendency to chew them up on ground loops. I am going to try and have them connect with a joint to help reinforce the foam hinge. I will certainly share them here for anyone interested.

[2much2do]

Something like the tip skids Mike Patey puts on all his airplanes?

Just FYI these are for sale all over:

https://www.motionrc.com/products/du-bro-60-9mm-2-40-wing-tip-tail-skid-2-pack-dub992

[Atrix]

I have seen that style and actually have a similar set on the way, but I am going for something a little different that would actually glue to the ends of the ailerons and wings to protect the foam if it does make contact with the ground.

[skiervh]

My wings have been pretty tight when installing and removing from the fusalage. On my 7th or 8th time removing wings, noticed some separation here. Easy fix but just something for others to be aware of.

[FlyinTime]

Any tips on gluing the tires on the wheels? Never had to do it before

[2much2do]

Any tips on gluing the tires on the wheels? Never had to do it before

Go slow and use one of the little pipet tubes if you have it. Then just go over it again without leaks. Something i was told after i did it was to add a ring of soft foam inside so that even if they go flat you have something to roll on other than the plastic rim.

[FlyinTime]

Something i was told after i did it was to add a ring of soft foam inside so that even if they go flat you have something to roll on other than the plastic rim.

When I was watching some YouTubes on gluing tires for RC cars, They had what looked like foam inserts in them. Good idea, thanks

[Starck Mad]

Ok guys! Our update video is up on Youtube (Model AV8R). We show how we fixed the tailwheel issue and show some taxi tests. We do some watt meter readings on 6s and 4s and show how to maximize the power on 4s, and show some maximum performance flight footage with both 4s and 6s. Check it out!

[Starck Mad]

Just an update from my weekend exploits with the Bison. We had an event at my local field, and I got some more eyes on the Bison from the crew of experienced pilots. Everyone was a bit flummoxed by the tail wheel and its tendency to not track very well (especially after some rudder input), making take off from the paved runway very tricky. There were a good number of failed take offs and ground loops and unfortunately the ends of my wings are bit beat up as a result. Once we switched to takeoffs in the grass, things improved quite a bit, but I am not entirely sure why, maybe less traction on the rear wheel meant less likely to be taken off course 🤷♂️

In any case, once I could take off with some regularity, I got through about 5 packs without too much trouble. In the air, I am still having to trim rudder, but other than that it was well behaved. I was doing low, slow passes all day with a few rolls and loops tossed in here and there. I have flaps mixed with elevator, but I have to tweak that a bit because I still pitch up on half flaps and pitch down on full flaps. Despite all the interesting challenges, I am still quite happy with the Bison and really enjoying it in the air (less on the ground).

Some things in the works. As you may have seen above, I am working on a springless tailwheel setup. I will report back how that goes this weekend. Also, I am designing 3D printable custom wing/aileron skids to help with my tendency to chew them up on ground loops. I am going to try and have them connect with a joint to help reinforce the foam hinge. I will certainly share them here for anyone interested.

Atrix the issue taking off...and landing from pavement is mainly due to the tires. They grip really well and since they are so much softer than say the Du Bro Big Wheels (which I run with no air...they are rigid enough) and require air...its really hard to get the pressure equal on both sides. I have the same issue from our geotextile runway. I do run mine with less air for less bounce which makes this worse...more air/stiffer would make it easier. That said I prefer the grass with a bush plane anyway.

[skiervh]

Ok guys! Our update video is up on Youtube (Model AV8R). We show how we fixed the tailwheel issue and show some taxi tests. We do some watt meter readings on 6s and 4s and show how to maximize the power on 4s, and show some maximum performance flight footage with both 4s and 6s. Check it out!

Great video Stark! Where are you mounting your battery at in relation to CG? I feel like if I measure back 57mm or even further back like others have....that battery wont be anywhere on the mounting plate and too far back to even throw the straps around. Could you post a pic for reference?

[Starck Mad]

Great video Stark! Where are you mounting your battery at in relation to CG? I feel like if I measure back 57mm or even further back like others have....that battery wont be anywhere on the mounting plate and too far back to even throw the straps around. Could you post a pic for reference?

With the 4s packs (5000's) I have it to where the front strap just does go around the battery. With the 6s packs (3700's and 4000's) I tuck them under the tray slightly and the front of the pack is clear of the front strap...I just use the rear strap. I think our balance point is 77mm from the front of the slats. Our full set up is in our first video. Thanks for watching! Sub...we have much more coming!

[asesso]

The manual appears to show the CG at 57mm from the front of the slats. It seems like it should be measured from the leading edge instead. Which is correct?

[2much2do]

The manual appears to show the CG at 57mm from the front of the slats. It seems like it should be measured from the leading edge instead. Which is correct?

The manual appears to be wrong, please see the post directly above yours. 70-77mm behind the slats seems to be where everyone is landing.