Tail dragger deck angle

[jmodguy]

For those of you with tail draggers, what is your deck angle and how does that affect your landing? I’m measuring about 10 deg and a buddy says I should be closer to 17... he is an accomplished tail wheel instructor.
What say you?

[efwd]

wouldn't that depend on the gear and wheels your using? Certainly my deck angle is different than the STI and steeper than the speedster.

[rv9ralph]

Deck angle would only come into play if you were concerned that the wing will stall when landing when the deck angle is the same as when the aircraft is sitting still on the ramp. Not really a big issue. If you watched the videos of Draco landing at AirVenture (Follow Mike Patey's or Trent's YouTube channels) his deck angle was way higher than when on the ramp.

What happens if the wing doesn't stall at the same deck angle, the tailwheel will touch first, still not a problem.

Ralph

[PapuaPilot]

I am guessing you are asking what the nose up angle is when the plane is sitting on the ground. If so mine is about 10 degrees using the Desser 22" tundra tires.

[jmodguy]

Thanks for the quick responses!
You are both correct and I understand the mechanics of the landing and the aircraft setup. Yeah Draco is a pretty sweet machine!
I am looking for some data points, i.e. real world Kitfox deck angles and how (if) they affect landing speeds and attitudes. My friend has considerable tailwheel experience and is our “go to” guy for advanced tailwheel training. He does not have much experience with the Kitfox though so he is curious.

[jmodguy]

Thanks Phil. Thats what I’m looking for. Any issues/concerns during short field ops?

[rv9ralph]

Jeff, you have a model 5, which has more elevator authority than my model 3. The effectiveness of the elevator at flair and touchdown is what helps on landing as slow as possible. Deck angle is not that critical, it is how slow you can get before the wing stops flying. At AirVenture, I looked at Trent's and another Kitfox I believe it was a model 5 if I remember correctly, parked with the Cowboys, they both had gap seals on the elevator. This adds to the effectiveness of the elevator. My model 3 doesn't have as much elevator authority, it is against the stops (the truss at the front of the seat) when in flair. I have thought of gap seals for the elevator and will probably do that in the near future. Again, it is how slow you can get before the wing stops flying, higher deck angle is the flair usually corresponds to slower speed... and shorter roll out after touch down.

Ralph

[Delta Whisky]

Jeff - in the golden olden days it was said that most wing profiles stall at about 18 degrees so many airplanes that had the tail wheel at the correct end of the fuselage were designed with a deck angle of about 18 degrees (plus or minus a bit). The theory was that since your landing should be made with little or no power and in a three point at stall, that was the perfect deck angle. With the advent of items such as higher power to weight ratios, VGs, new computer designed profiles, and a real interest in landing in a winner at Valdez, all bets are off. If you are trained and experienced in landing with your tail wheel hitting way first, then why not less than 18 degrees? Your instructor will have an opinion on that answer.

[jmodguy]

Thanks all for the inputs!
Ralph- I will be adding vg’s at some point. Would like to establish a baseline first.

Delta- your post probably is the reason my friend was looking for a higher deck angle. He likes the older slow small planes, i.e. champ, luscomb, chief etc etc

[av8rps]

For years Kitfoxes and Avid flyers had too short of a gear making good 3 point landings difficult because you couldn't get the wing to stall fully without hitting tailwheel first (which used to be considered a bad landing :) ).

Nowdays people are landing tail first a lot of the time with their STOL aircraft, but they have aircraft with tailwheels designed for that. A regular tailwheel spring will not survive many of those tail first landings, and neither will the tail section tubing of the aircraft.

I've heard our earlier under cambered wings need around 20 degrees to stall and the later ones 17 degrees. Maybe those with a good Angle Of Attack guage could confirm?

Not only does a taller gear with big tires look better on our Kitfoxes, but it will also work better. My Highlander on 29's works well with a high angle, but I've never measured the ground angle. I would guess it to be similar to the STI with 29's. If you want to land short and slow it is better to have too much angle rather than not enough angle. Just my two cents worth.

[jmodguy]

Good analysis av8r... when I wear out my 22s I’ll look at the 29+ tires.

[PapuaPilot]

Thanks Phil. Thats what I’m looking for. Any issues/concerns during short field ops?

No everything is great, but I'm sure I could land even shorter if I wanted to land tailwheel first. Normally I land in the 3 point attitude which can yield a 200-250' rollout if I'm light. I am usually at a forward CG which is not the best for the slowest stall speed/shortest landing. I upgraded to the larger elevator during my build (this elevator is standard on the SS7). I recently added gap seals on the elevator using heavy duty clear Gorilla tape and I can notice a difference in elevator effectiveness.

[Esser]

I haven’t measured since I put my 26 ABW on. I was at 13.5 degrees. I’m probably at around 16 deg. Now

[jmodguy]

Josh
I was right at 13 deg with the Desser 22's, stock 3 leaf tail spring and a Matco 9" tailwheel. If I go with 29s for next set of mains I'll prob be back around 13 deg or so.

[AirFox]

My 7SS with the Shock monster on 26" ABW and T3 Tailwheel spring sits at 14 deg. I just put 29"s ABW on so it may have increased a small amount. I'll check.