Bearhawk STOL mods

[zkelley2]

I was over at Carbon Concepts the other day and he has some really interesting new flaps on his cub. Single slot with a kevlar based compliant hinge for the second. I think the install would be wildly simpler on our airplanes.

I guess through testing they were finding the second slot was doing nothing at all for keeping the airflow attached at our slow speeds.

I really want to get the deck angle down to. I'm landing tail first about 100% of the time if I want to be slow. A water landing acceptable deck angle is around 50kts. Pretty fast.

[Dave Roberts]

Thanks. Yes deck angle would be a big deal.

[Battson]

Totally agree, that is my main interest in this product.

[zkelley2]

Sounds like they have done what was expected, small reduction in stall speed and much flatter deck angle (about 50% closer to level). From what I understand, testing finished a long while ago.

I expect this plane will come up for sale sometime in the future, for unrelated reasons.

Even if you got no reduction in stall speed, getting the deck angle down when flying slow would be a tremendous stol mod.

[Battson]

Are there any updates on the double slotted flaps? Thanks Dave

Sounds like they have done what was expected, small reduction in stall speed and much flatter deck angle (about 50% closer to level). From what I understand, testing finished a long while ago.

I expect this plane will come up for sale sometime in the future, for unrelated reasons.

[Dave Roberts]

Are there any updates on the double slotted flaps? Thanks Dave

[Westward_Flyer]

With the increased gross weight of the model 5 are the more extreme (plan altering) STOL mods off the table? Such as fowler/slotted flaps, wing extensions, etc.
I'm assuming the other mods will be fine since it uses the same wing as the model B.

[jetdriver]

Hi Battson, thanks for the information you shared about these flaps, it's been helpful. Any update on the testing from the owner? Has he made further modifications and do you have video you can share? Thanks.

[JimParker256]

Kitplanes has been running an excellent series of articles on aircraft design. It has given me a lot of insight into the compromises and trade-offs made during that process. More fuel -> more weight -> stronger wing structures -> more weight -> more power needed -> more fuel, repeat ad nauseum... Understanding those trade-offs a little better have given me even more respect for Bob and his designs... No design is perfect, but Bob's designs produce some pretty incredible airplanes!

[Gerd Mannsperger]

You are correct Kestrel weight is not everything, I would not want to weaken the airframe or landing gear for example.

However if you add more weight you will need to go to heavy duty landing gear and brakes for the higher weight - adding more weight - eventually you will need more HP = Bigger engine More weight now your stall speed goes up and you need to extend your wings to make up for it and on it goes. I hope you get my point.

[kestrel]

Generally true. However, Frank Knapp (a _BIG_ fan of light) ended up adding slats, complex flaps and a more powerful motor to beat the big guys. Weight is _almost_ everything, but not absolutely everything.

[Gerd Mannsperger]

Yes been there done that.

But I pulled 160 pounds of misguided perceived needs out of my last Cessna 206 and 120 pounds out of my last M7 all in Vacuum systems Avionics auto pilots and heavy interiors.

The Airframe and powerplant are still all stock.

Paint is a big one too, more so on fabric aircraft.

On the Maule I saved 25 pounds alone on the paint when I painted it and did the fabric.

Both Aircraft already had lightweight Starters and Alternators but still have stock Batteries. If this is on the table on certified aircraft imagine what is possible to the builder of homebuilt aircraft.

If STOL is your game watch the Weight

[Russellmn]

Building simple and light is easy on the face of it, until you start really chasing grams, then it gets REALLY expensive!

[Gerd Mannsperger]

The most effective of all STOL mods is also the cheapest one.

Weight -- less is more.

If you want STOL capability exercise discipline build simple and light.

Just got back from a Photo / training flight on some local sandbars with light aircraft and it is so easy.

Usually I am always at gross weight ( for work) and it is a whole different world --weight should always be the first consideration for a STOL aircraft.

[Battson]

Mine are exactly 10" forward of the rivet line running down the main spar. I found this location gives the VG the approximately full exposure to the airflow at the stall AOA.