Leading edge slats and Keller Flaps

[BC12D-4-85]

I'm watching the progress and so far the owner is flying minimal flaps and normal AOA on approach. Big tires (35's) are unnecessary for flat ground with that Porter long gear. Lots of bounce at speed. The plane wants to lean over after landing. Sit in the airplane and see what's visible for LZ is what I'd do 3-point. Any more AOA offers slow flight but with no over the cowl landing reference with those LE slotted flaps vs the earlier P-STOL design apparently. Trading AOA to get lift and drag with this design versus drag and lift with P-STOL flaps in that order is apparently a choice. Not sure why besides the experiment between the two...and then floats which might be better? If you don't have to point the nose at the LZ the flaps aren't effective enough in my opinion.

Gary

 

[stewartb]

Your assessment is incorrect. Watch the video Kevin linked in post #117. With the possible exception of the prop, the two planes are identical. That wing has plenty of slow flight performance capability. If there’s a down side, it’s weight. The Rev 3 wing is heavier.

 

[BC12D-4-85]

Your assessment is incorrect. Watch the video Kevin linked in post #117. With the possible exception of the prop, the two planes are identical. That wing has plenty of slow flight performance capability. If there’s a down side, it’s weight. The Rev 3 wing is heavier.

Yes I may be incorrect and in fact is only based upon the T&G's I've observed. The factory info claims minimum speed in the upper teens and 20's. I agree that's what they've discovered unless proven otherwise. Hence these questions.

Is the new owner flying faster than necessary to learn the aircraft? If so why is it at minimum flaps and low AOA for some reason? The approach is nose low so the slats may not be working to advantage. Would P-STOL offer a better sight picture and apparently more drag? So far it performs like an ordinary albeit heavy Cub, but that's likely the pilot not the plane. And I don't know the weight of course.

The flaps in #117 are deflected more than what I've observed so far. Thanks for pointing that out.

Gary

 

[stewartb]

I can testify that the advertised landing speeds are correct with my 112" Pstol flaps. The 144" Rev 3 flaps should be similar once the driver gets used to using the lift component and not relying on the drag component. I 'm sure there's a learning curve. In fact there's a learning curve for the whole airplane, not just the flaps. I can't imagine why he'd choose partial flaps. I see no benefit in that, but he may have a reason. If he hasn't figured it out already, he probably needs to add some weight in the back. He may be fighting the plane without it. For me that was true in cruise but not for landings. If he's been fighting it he may not want to commit to slowing it down yet. Hopefully he does sooner than later. These big wings feel ground effect more than any others I've ever flown.

 

[BC12D-4-85]

I assume the 2nd seat is an instructor (?). If so that my determine the behavior I've observed so far. I think I'd try to find someone experienced in the design to demonstrate then instruct, and go from there.

Gary

 

[stewartb]

Has the wind been blowing? They may be trying to minimize the plane's reaction to wind.

 

[BC12D-4-85]

No significant wind during the evening's training sessions so far. I speculate the BCSC in question takes rigorous instruction to properly fly within the proven edges of its envelope. They are not a common C-150 or 172, and have special features that I assume require a stepped training program.

If I were learning I'd ask for considerable flying first, then progressive stages to explore both takeoff and landing. That's probably what's happening and I just happen to have seen a portion of all that.

The few Helio Courier pilots I've known and have flown with talk about that same process. It takes focusing on and learning the specialized aircraft's behavior. Just random flying prolongs that process in my experience but with other aircraft.

What would be revealing would be someone like you, that has flown similar aircraft but with different components, to evaluate the III version. Has anyone offered that comparison yet?

Gary

 

[DENNY]

Trying to find any tailwheel instructor is getting hard in todays world. Finding one with experience is even harder. Some of the newer CFIs I have flown with did all the training without flap use for takeoff and landing. They in turn train the students that way. Fear of flaps on landing/takeoff is not uncommon with new CFIs. Sometimes you just take what you get. It could just be he is wisely just doing small changes at a time to get used to the aircraft. DENNY

 

[BC12D-4-85]

It's really none of my business. Same thing I said about the recent loss of a flying friend that had a brief history of control decisions. Guess that taints my comments.

Gary

 

[stewartb]

I don't know how anyone trains for their first flight with slats, let alone the first flight of an experimental airplane. You just do it. It's fun.

 

[Litecub]

I have a stock round wing Cub with 66” P-STOL flaps and a 2’ stretch Mackey assist build Monster Cub. They are very different in how they fly at the slowest/high angle of attach region of flight. The Mackey Cub has slats, SQ 2 ailerons, 8’ P-STOL flaps on a Javron wing with 8” extended gear. The wing at 3 point is at 17 degrees so shortest take off is best accomplished by staying 3 point and let it fly when the wing is ready. Landing for shortest possible ground roll is carry moderate power at high angle of attack with the tail wheel touching first. In this configuration the 35” main gear can be still well above the ground, the angle of attach drops when the tail hits the ground dropping the mains in a plop landing some where below 30 MPH, 150 feet in no wind to stop with moderate braking. I have not flown the Monster Cub without the slats and will keep them on for the slow speed performance and safety.

 

[tempdoug]

I have a stock round wing Cub with 66” P-STOL flaps and a 2’ stretch Mackey assist build Monster Cub. They are very different in how they fly at the slowest/high angle of attach region of flight. The Mackey Cub has slats, SQ 2 ailerons, 8’ P-STOL flaps on a Javron wing with 8” extended gear. The wing at 3 point is at 17 degrees so shortest take off is best accomplished by staying 3 point and let it fly when the wing is ready. Landing for shortest possible ground roll is carry moderate power at high angle of attack with the tail wheel touching first. In this configuration the 35” main gear can be still well above the ground, the angle of attach drops when the tail hits the ground dropping the mains in a plop landing some where below 30 MPH, 150 feet in no wind to stop with moderate braking. I have not flown the Monster Cub without the slats and will keep them on for the slow speed performance and safety.

Picture???

 

[Litecub]

The requested picture of the “Monster Cub” at 5,000’ elevation and yes that is the name on the registration

 

[spinner2]

I have a stock round wing Cub with 66” P-STOL flaps and a 2’ stretch Mackey assist build Monster Cub. They are very different in how they fly at the slowest/high angle of attach region of flight. The Mackey Cub has slats, SQ 2 ailerons, 8’ P-STOL flaps on a Javron wing with 8” extended gear. The wing at 3 point is at 17 degrees so shortest take off is best accomplished by staying 3 point and let it fly when the wing is ready. Landing for shortest possible ground roll is carry moderate power at high angle of attack with the tail wheel touching first. In this configuration the 35” main gear can be still well above the ground, the angle of attach drops when the tail hits the ground dropping the mains in a plop landing some where below 30 MPH, 150 feet in no wind to stop with moderate braking. I have not flown the Monster Cub without the slats and will keep them on for the slow speed performance and safety.

Having ridden in the backseat of this Monster Cub it is extremely impressive how slow it will land. After the first landing I commented over the intercom that I thought I could run almost as fast as we had just landed. I’m sure I actually couldn’t but it seems like it is landing in slow motion, rolls out for a few seconds and stops.

I’m not used to sea level performance and that was part of it. But there wasn’t any headwind to speak of helping. And I could add that I have several thousand landings in a 1000 pound Carbon Cub so I know what good performance is.

 

[Lowleveldevil]

I figure 100 knots so if they slow me to 95 knots I really don’t care as I sold my Bonanza and RV7 to build this so speed was never my priority. It would be nice to have the exact speed figures with and without.

 

[courierguy]

10 mph is what Joe Dory told me once.

 

[Colorado-Cub]

10 mph is what Joe Dory told me once.

Next time you see Hal ask him what the slat hit is to his Seven. I see pictures of him competing with them, but pulling them off for the trips home.

Also ask him why he never runs the inboard slats?

 

[ak-mikeo]

Hi my name is Mikeo here is my idea of a stol cub http://youtu.be/woQrg4rHBto

 

[ak-mikeo]

Messed up the link it’s thunderbird one on u tube

 

[JP11]

I doubt that was a driving factor. We all balance nose heaviness with weight. Added length doesn't solve it. Even with my long airframe I have 40-50# shoved in back behind where the CG instructions suggest a 10# maximum placard. My engine mount is as short as it can be without modifying the firewall. Slats move the aft CG limit back an inch. I believe they should move the forward limit back as well. My plane's a handful to fly near the forward limit.

My nephew's Mackey SQ-12 airframe is extended further than mine. These things keep evolving.

Haven't been here in a while. Happy to be reading this stuff again. I'm the one tom put slats and PSTOLs on.

Long wing TCOW. Slats and PSTOLs. and VGs. I have 3" extended gear. Slats aren't doing much of anything for takeoff. I'm on 31s.. and the AOA just isn't there. I JUST finished my hangar at home since Twitchells is closing. Next will be separate gear for skis/wheels. I'm gonna do 6" extended for my 31s. I figure that will get me to a good 3 point liftoff.

I just had the experience the other day of it feeling squirrelly with a forward CG. Since I lost my local fuel.. I hopped over and had maybe 30gal in it... with just me. It seems like it's real trim sensitive to rear seat pax. I joke that it's more 'science experiment' than cub now. It will do some strange things. My comments about doing the mods were.. I'd do the flaps twice! Massive improvement... moreso on floats than wheels. It just really brings the sweet spot for the wing down close to the sweet spot for the floats. The slats.. yes, there's a safety factor there. Yes, you can make it do dumb stuff. I'm operating off 1600' with a massive power line on the end. I still don't need the slats.

As for taking off the inboard set.. or pinning them. If you do the math, to me.. it's just not worth the time or effort. MAYBE if you were going all the way across the country, it would be worth it. I was slower than all my buddies before, I'm still slower. I just hang with the 100hp guys instead of the 150, 160 and 180 guys.

I'm gonna throw my gear in the aft baggage, and see if that helps out my feel. I still love it, it's a goofy plane. It's just for hop around fun for me.

 

[JohnnyR]

Nice update.

Q: Are your tailfeathers stock PA-18?

Haven't been here in a while. Happy to be reading this stuff again. I'm the one tom put slats and PSTOLs on.

Long wing TCOW. Slats and PSTOLs. and VGs. I have 3" extended gear. Slats aren't doing much of anything for takeoff. I'm on 31s.. and the AOA just isn't there. I JUST finished my hangar at home since Twitchells is closing. Next will be separate gear for skis/wheels. I'm gonna do 6" extended for my 31s. I figure that will get me to a good 3 point liftoff.

I just had the experience the other day of it feeling squirrelly with a forward CG. Since I lost my local fuel.. I hopped over and had maybe 30gal in it... with just me. It seems like it's real trim sensitive to rear seat pax. I joke that it's more 'science experiment' than cub now. It will do some strange things. My comments about doing the mods were.. I'd do the flaps twice! Massive improvement... moreso on floats than wheels. It just really brings the sweet spot for the wing down close to the sweet spot for the floats. The slats.. yes, there's a safety factor there. Yes, you can make it do dumb stuff. I'm operating off 1600' with a massive power line on the end. I still don't need the slats.

As for taking off the inboard set.. or pinning them. If you do the math, to me.. it's just not worth the time or effort. MAYBE if you were going all the way across the country, it would be worth it. I was slower than all my buddies before, I'm still slower. I just hang with the 100hp guys instead of the 150, 160 and 180 guys.

I'm gonna throw my gear in the aft baggage, and see if that helps out my feel. I still love it, it's a goofy plane. It's just for hop around fun for me.

 

[JP11]

Unchanged from the TCOW kit. I didn't build it. Sure looks stock. Of course has bottom of horizontal stab VGs. Has gap seals.. those made a big difference in 'running out of elevator'

JP

 

[stewartb]

Thanks for the comments. Longer gear allows me to carry a little power to maintain a slower speed to land. My static AOA increased 2° with 6” gear compared to 3”. Not the end-all solution, I can still bump my tail, but a clear improvement with no down side.

To me takeoff is about thrust and acceleration. Slats allow a steeper, slower initial climb out but that’s not something I do normally. The flaps are the better tool for reducing ground roll. That and horsepower.

I hope weight in back does for you what it did for me. With that plus a couple of hundred pounds in forward cargo my plane flies even better, and that makes me happy. Heavier tail so a bit longer take off, but not much difference in approach or landing speed. Definitely less trim sensitive.

 

[JP11]

Thanks. I'm not REALLY doing the longer gear for STOL contest or anything. it's a 'fat girl' for sure. Was built as a heavy hauler. I've got 4 tanks.. 68gal. It's at about 1350empty on 31s.

I just figured, If I have to buy gear (i want them to make the swap to skis easier. I have 6s.. and single pucks for my datums, I'd rather leave it all together and just pull gear as a whole) I'd go with 6" extended. I figure I can land it tail first working the slats. My best in a contest was 178ft landing. but the takeoff is up closer to 275 to 300. No real 'need' to come off low energy like that in any kind of daily use.

Trim is interesting with the PSTOLs. I just don't need to trim with speed changes. the change in wing shape does it for me. The strange part is it only used to be able to stall if the stick was buried aft. I joked that the stick compressing a bit of the rear seat cushion was the 'stall warning'. Now.. with slats..it's goofy town. You can stall it stick centered. All sorts of strange stuff going on. You can get on the power, get it stupid slow.. heat up the motor with no airflow. Again.. not a lot of it is practical. PSTOLs for visibility coming downhill to a small spot is gold. Slats are a safety margin... and some weird aerodynamics. I'll do some pancake turns and flip directions.. tons of rudder and opposite stick.. (up high of course) just to show friends the dumb stuff it will do. Just my .02. Do with your money what you want. If I had to do it over again.. I probably wouldn't do the slats. I don't really regret it though.

Anxious to throw that weight aft. Thanks for the tip.

JP

 

[stewartb]

Is your airframe extended compared to a stock Cub? Do you have electric trim? My answer would be yes and yes. I use full nose down trim and three notches of flaps for normal take offs. The tail lifts quickly and after a few seconds I lower the tail and it flies off in a very comfortable AOA. Get airspeed, retract flaps, my thumb is on the trim switch to reduce stick pressure, and hold 60 mph to climb out. Things happen fast during take off and slow during landing. My trim starts at full nose down and finishes at full nose up with every flight. I appreciate the electric trim.

I enjoy this topic and hope the discussion helps other guys considering slats. Thanks for participating.