Official Skynetic Bison XT STOL Discussion Thread

[4923crew]

Some pictures of the Bison for everyone to enjoy. We found the bison to be a super fun bird to play around with, its all terrain suspension is super durable and took tons of incredibly hard test landings with ZERO issues. With The Bison over 100 test flights on it, we found that you can obtain a better flight envelope than the majority of other brand stol birds, especially if you add a gyro like some other brands. the leading edge slats are an awesome option but we found that the bison really only needs minimal deflection in them to get the best STOL landings and takeoffs. As Ive seen mentioned in previous posts the tires should be glued onto the rim with “Rc car tire CA” but applied in small amounts and only in about 1/2” lengths until both sides are completely glued in place. You can put too much pressure into them so at first, only get the tire pressurized to hold the weight of the bison without being too soft and sloppy on the ground. As a recommendation, add some CA to the wingtip lights because after lots of flying, the double side tape will eventually un-stick and you dont want to loose the light assy. For best results give a quick burst of throttle right before landing to cushion your landings.

All in all the Bison is large durable stol bird that loves the off road approach to the rc flying hobby. have fun with the Bison because we have.

[2much2do]

The bigger prop is for 6s right?

[Gilatrout]

Oct4 seems like forever

[MJ4RC]

Ordered mine this afternoon when I did my hourly check to see if it was available lol. Anyone know if this has a modeled dashboard?

[Warlox]

Looks like I’ll have to make my own interior details. Still going to be a fun plane.

[MJ4RC]

Motion RC Team, Kindly please help:
1. Please advice to where all the screws are used (size wise) . Nothing in the assembly guide indicate to what screw size goes to the undercarriage, struts, tail wheels, stabilizer or the main wing.
2. I connected the light controller to the gear channel. After a couple minutes, the controller got very hot to the point that controller shrink tube starts to melt.

Kindly please advice. Thank you in advance.

[Topshot19]

Tom is right, among all the craziness associated with international overseas container shipments in the current era, we had never heard nor encountered a random 3 week delay in Chicago.

Thankfully, they're here, and they're shipping.

hey alpha! What about the floats? I know there was talk about it before? What is the update on the floats?

[Bazza]

How about naming or nominating an Australian distributor that us aussies can buy it without the almost $600AUD freight fee, Pleeeeeeeeease

[AussieHoppy]

... also you start by talking about the slats but then call them the flaps. I agree that the gap between the front of the FLAPS and the rear of the wing should be as small as possible, but the gap between the front SLAT and the leading edge of the wing is designed so that the flow over the slat joins up and sits on top of the airflow that goes under the slate and over the wing leading edge, see from the 3 minute mark of this youtube https://www.youtube.com/watch?v=TgncesRfqho ,also have a look next time your in a Qantas or Virgin jet taking off or landing, there is NO gap between the flaps and the trailing edge of wing and a reasonable gap between front SLATS and leading edge of wing. it is designed to give an almost second wing worth of lift due to two layers of air having to travel faster than the air under the wing

... lifting the trailing edge of the flaps seems to do nothing but disturb the air flow creating disturbance over the boundary layer, which is counter-productive for STOL?

Oooops! My apologies! I knew what I was talking about... 😏 swap "flaps" in this line for "slats", it might make more sense lol
I wasn't intending to make any reference of the flaps other than the slats actuated by the flap servo.
What you've stated there, is what I was failing to say :)
From what I have read (yes, text book learning only, soon to experiment real world) the gap between the leading edge of the slat and leading edge of the wing is generally a reasonable sized gap, where-as the gap between the trailing edge of the slat and wing surface is a much smaller gap, for reasons you have already noted (airflow/boundary layer).
But the slat setup on this Bison has the slats hinged and actuated by a pushrod off the flap servo, it looks to me like the pushrod pushes the slat up which closes the leading edge gap a little but worse, it lifts the trailing edge of the slat up creating a very large gap. With the trailing edge of the slat up high it doesn't encourage smooth airflow over the wing but act more so as an airbrake and creating a bunch of turbulence which disturbs the boundary layer, counterproductively.
The Seagull Savage Shock Cub had the same setup and didn't work, in fact a few guys quickly crashed it because with the slats standing up it was destroying lift at stol speeds and creating turbulence not unlike an air brake. Most guys either fixed them in place or removed them completely.
Seems to me the slats should be on slides if they are to be actuated by the flap servo, so being pushed forward the leading edge slat gap opens up while the slat trailing edge remains the required smaller gap.
I should look into the Freewing T-45 Goshawk with their leading edge slats done properly. Quote from MotionRC's site:

"The Freewing T-45 sets itself apart from the competition with numerous scale details and innovative features such as servo actuated speed brakes and plastic wormgear-driven slats. These slats are the first production release of a proper slat in a foam model of any size, and use aluminum tracks to ensure proper extension geometry. Other plastic details include a row of turbulators on the wings..."

I love these slats! Have a peek at the comparison pics attached.
I like the idea of turbulators or VG's too, but that's another discussion lol

And for stol I don't mind at all a gap between trailing edge of wing ~ flap leading edge, like you achieve with offset hinges, this creates turbulence and acts as an airbrake where it should.

Sorry guys for the essay [my fingers are typist cramping now...], the only reason I am encouraging this topical discussion is because guys crashed their 1/4 scale Cubs underestimating the air brake/lift destroying slats that lifted at the rear... hoping to highlight this issue here so guys don't crash this Bison inadvertently, is all.

[AussieHoppy]

Hey AussieHoppy where will you be buying yours if you do go ahead, see my comment above re freight

I don't know at the moment. As per usual all the containers bypass us and head around the other side of the planet first. I'll keep an eye out around the usual Asian retailers, I might see if Budget Hobbies or even Metro Hobbies will stock them, but most likely Aussie retailers will be ordering through an Aussie wholesaler like OMP so we'd have to wait months (literally) for the last container out of the manufacturer. And as you mentioned, trying to purchase from USA is pretty much financially unjustifiable these days due to crazy freight costs.
I'd really like one of these but I'm going to have to be patient...

[Bazza]

AussieHoppy looking at your photos, that most certainly should be called a ShockingCub, anyone with any small amount of know how on how lift from wing shape works could see that the setup pictured was doomed to be a disaster, and to be honest I am not sure why it would have even been produced as a prototype let alone go into full production. Seagul used to make good planes, they were the first non diy plane I ever owned, don't they test fly anything before going into production anymore? To be honest I am SPEECHLESS after looking at the shocking Cub

[2much2do]

Bazza, do you think the bison will be different?

[Denc23@comcast.net]

Mine shipped Wednesday, arrive scheduled for Tuesday the 28th.

[Aros]

Hi everyone, we've updated the manual to include specific callouts for screws. The updated manual can be found HERE.

[MJ4RC]

Hi everyone, we've updated the manual to include specific callouts for screws. The updated manual can be found HERE.

Thank you very much. 👍

[Scott Ellis]

Looks very cool, but . . . short takeoffs by means of a little flap and a helluva lot of power are nothing but a cheap party trick. What distinguishes a real bush plane is good manners in VERY slow flight. The weight of this thing makes me wonder if it will fill that bill, but if it will, then you certainly ought to put up some video showing it doing so!

[AussieHoppy]

AussieHoppy looking at your photos, that most certainly should be called a ShockingCub,

Yup lol yet this Bison has the same hinged slat actuation, not as much travel as the Savage Shock but still, same hinged slat mistake? Apparently the Savage Shock flies very nice and predictably slow with the slats completely removed, which speaks volumes.

.... the leading edge slats are an awesome option but we found that the bison really only needs minimal deflection in them to get the best STOL landings and takeoffs.

And speaking of volumes, to quote from 4923crew (I don't know how I missed this post entirely, thanks for the review 4923crew :) ), it would appear he has already discovered the slats don't work for stol while they actuate pushing the slat's trailing edge upward, my take from this would be to fix them in the trailing edge down position keeping a small gap, just how small the gap needs to be will be the experimental part.

[AussieHoppy]

Looks very cool, but . . . short takeoffs by means of a little flap and a helluva lot of power are nothing but a cheap party trick. What distinguishes a real bush plane is good manners in VERY slow flight. The weight of this thing makes me wonder if it will fill that bill, but if it will, then you certainly ought to put up some video showing it doing so!

If we can accept this appraisal below, then one would assume it should perform stol as expected. Although I'm not sure what to make of the reference to gyro use lol
Yes, it would be nice to see video proof of very/extreme slow stol capabilities...

With The Bison over 100 test flights on it, we found that you can obtain a better flight envelope than the majority of other brand stol birds, especially if you add a gyro like some other brands.

[Atrix]

Today is the day.

[MJ4RC]

The bigger prop is for 6s right?

Hello, Can anyone please answer this question? Thanks in advance.

Prop 15X8 or 16X8 for 6S lipo?