Correct me if I'm wrong

The Show Planes FPS for the RV 10 has 4 settings. The problem is full retract takes it to the reflex position (position one), then you need to bump it forward to the zero setting (position two) i.e. If you had a sudden go around scenario. I was looking at the Show planes, FPS-plus reflex. It looks like on retract it go's to zero. But you can bump it into a preset reflex position during cruise flight.

Am I correct or did I miss something. Those of you that have these units I would like to hear your input before ordering one or the other. Thanks...

That is how mine works, but I have never had an issue with it-------for a go around, just hit the switch to up, and pour on the coals. The 3 degree up is not noticeable IMHO.

I'm with Mike. To take it one step further, I never takeoff with the flaps at zero. I always use the reflex position. If I am doing short field or soft field work I would use 15 degrees, but the zero position, IMHO, is useless. I have a Vp and I set it for reflex, 10, 20 & 30.

I use the 0 deg setting in a few cases. I am glad to have it. I like to use it when i am flying slower than 120 IAS. I use it when i am flying slow to give a scenic tour or something like that. It really helps the plane fly slower.

Also, i use it such as in the pattern, on final or after the FAF. Again when i am flying slower than 120 IAS.

I keep meaning to experiment with 0 deg flaps in cruise up high. My one try (at DA = 16K') I couldn't tell any difference, but it wasn't perfectly smooth that day.
I agree with the others, on retraction the motion is slow enough that going all the way up on a go-around is no issue, with the-10's power.

BobTurner said:

I keep meaning to experiment with 0 deg flaps in cruise up high. My one try (at DA = 16K') I couldn't tell any difference, but it wasn't perfectly smooth that day.
I agree with the others, on retraction the motion is slow enough that going all the way up on a go-around is no issue, with the-10's power.

Click to expand...

I didn't try 0 per say. I used -3 for all the way up, -1 for down about 1/2 inch at trailing edge, 1 for down about 1 inch at trailing edge. I don't know the exact degrees....

Based on these tests. I now fly with the flaps down approx at the 0 degree position from take-off and climb until the IAS reaches 135 knots then retract to the reflex position.



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Correct me if Im wrong

0 degrees flap setting gets you off the ground several hundred feet shorter than reflex. My flap settings are... -3 (cruise), 0 (take off), 1/2, and full.

From my transition training notes: "Cruise in flap reflex position. Flying flap reflex in pattern acts to slow airspeed. Takeoff using flap reflex adds 200-300? to roll out."

Cheers,
Jay
N433RV - flying

Previous post was updated to include onedrive link.

This forum will not let me use the picture embed from one drive

Ok, so is the standard reflex position -3 degrees. I have read older post where some have "played" with the reflex setting in cruise flight using somewhere close to -10 down to zero. How is this done. Does the flap control allow intermittent stops. If Im not mistaken, the reflex increases air speed by reducing drag on the airfoil, the wing. Having a negative camber does not impact a take off/ go around since you have reduced available airfoil? -3 degrees is not to aggressive, so I can see maybe minimal airflow impact at low speeds, but I imagine if it was greater than that it would have some impact.

togaflyer said:

Ok, so is the standard reflex position -3 degrees. I have read older post where some have "played" with the reflex setting in cruise flight using somewhere close to -10 down to zero. How is this done. Does the flap control allow intermittent stops. If Im not mistaken, the reflex increases air speed by reducing drag on the airfoil, the wing. Having a negative camber does not impact a take off/ go around since you have reduced available airfoil? -3 degrees is not to aggressive, so I can see maybe minimal airflow impact at low speeds, but I imagine if it was greater than that it would have some impact.

Click to expand...

1. With most of the flap control systems installed, it's necessary to extend down to some pre-set, then put the switch full up to retract, then to neutral to stop the retraction at the desired point. You can stop anywhere you want on the way up, but not down. (well, you could flip to "up" while going down, but I don't like to do that).

2. Negative camber does reduce the lift available at some given airspeed and angle of attack. Given that you want to rotate at (to) some given angle of attack which has some safety margin over stall, while still providing 1g of lift, that means you need to be going faster if you take off at -3 deg (full up) vs 0 degrees (in trail). Personally I generally use 0 deg (in trail) for takeoffs, but cannot fault those who just take off with full up flaps. I do have to remember to retract the flaps once I'm up.

Ok, I got the visual on it. A little different than the three clicks on those Piper flaps. Thanks all!

I know this does not address your question since mine is installed in a 7A, but I absolutely love mine. It has worked flawlessly and I have the manual switch as well but I seldom use it.

Any position.

Apart from the flap position system question.

For a go around it seems not to really matter what the flap position is, even
if left all the way down you will achieve a significant rate of climb.

As a rule, I take off with 0 degrees of flaps and 10 degrees for short field
but it has more to do with embedding the habit of retracting the flaps once
I reach pattern altitude.

Peerhaps I can help

Perhaps I can shed some light on the question of reflex, since I designed the airfoil for the RV-10 for Van and proposed the reflex.

The airfoil is designed so that if you build it with really good riveting, and keep it clean, you will get some laminar flow, back to the skin seam at the spar.

Cruising with the flap reflexed to -3 puts the airfoil in the best position to get some laminar flow under cruise conditions. 0 flap should do better at best-climb speed.

Now, if your RV-10 is dirty, or you have a lot of dimples in the skin at the rivets, or you paint a stripe spanwise on the wing forward of the spar, then you are not going to get the hoped-for laminar flow. In that case, I don't expect you could tell the speed difference between reflex and zero flap.

If you were to build it really clean and smooth, you might find -5 reflex somewhat better than -3. But it is more difficult to maintain laminar flow at that angle, and likely performance will suffer a bit.

I grant that these differences may be so small that other factors in the build of the airplane may obscure the benefit.

But, here's the thing: you have about the same weight as a Bonanza. You have about the same engine as a Bonanza. And you go about the same speed as a Bonanza. Funny, the Bonanza has retractable landing gear. I think its fair to say the RV-10 wing makes up the difference in drag of having the landing gear out in the breeze.

Thanks Steve for the baseline on flaps at reflex. Always nice to get the real gouge.

Carl
RV-10 (300 hrs)

Flaps

As long as you are here...

There has been much discussion on flying the -10 for extended periods with the flaps at 0 and not reflexed. Specifically, many opinions have surfaced about the loading of the structure, i.e. in the reflex position, the flaps are against the rear spar, and in the flaps 0 position, the flap linkage is supporting the flap.

As you designed it, what is your opinion?

rocketman1988 said:

As long as you are here...

There has been much discussion on flying the -10 for extended periods with the flaps at 0 and not reflexed. Specifically, many opinions have surfaced about the loading of the structure, i.e. in the reflex position, the flaps are against the rear spar, and in the flaps 0 position, the flap linkage is supporting the flap.

As you designed it, what is your opinion?

Click to expand...

Steve designed the RV-10 airfoil. Not the wing structure, or its associated systems.

The flap system is designed to take flaps loads at full flaps up to Vfe, so extended flight with flaps at 0 deg instead of -3 should be no problem (I doubt that the loads on the flaps between the two positions are very different).

Having said that, I fail to understand why anyone would do this. What benefit do people think it is providing?

Keep in mind, that if the control systems are rigged properly, the ailerons (and wing tips) are reflexed all the time.

rvbuilder2002 said:

Having said that, I fail to understand why anyone would do this.

Click to expand...

Go back several posts and review the data on my airplane. It is faster when IAS is around 135 knots to have the flaps in trail.

Thanks Steve! I for one would never want to build a Bonanza or Beech wing. Tapered wing (unique wing ribs), some corrugated Al sheets on flaps or ailerons, combination of universal and flush rivets in strange configuration, leading edge attached with a piano hinge, load bearing flaps, and of course the retract gear. What a nightmare that must be to build!

First, Up until now I did not fully understand the reflex, but this has been very educational. But just to clairify the Flap Position Sensor.

Show Plane FPS: You have four positions: 1- reflex, 2- zero, 3- 20 degrees, 4- 40 degrees

Aircraft Extra with reflex: you have five positions: 1- reflex, 2- zero, 3- 10 degrees, 4- 20 degrees, 5- 40 degrees.

The 10 degree position is not needed so it is eliminated with the show planes?

Oh, and that was interesting info concerning how a stripe painted along the wing span can affect the airflow. Just gets back to the point that even a little icing can qiuckly become a big problem.

rvbuilder2002 said:

Steve designed the RV-10 airfoil. Not the wing structure, or its associated systems.

The flap system is designed to take flaps loads at full flaps up to Vfe, so extended flight with flaps at 0 deg instead of -3 should be no problem (I doubt that the loads on the flaps between the two positions are very different).

Having said that, I fail to understand why anyone would do this. What benefit do people think it is providing?

e.

Click to expand...

To paraphrase Steve, max laminar flow at climb speeds should be with flaps in trail.
At high enough altitude IAS in cruise will be around best climb speed, so the thought is you may see improved performance with zero degree flaps in cruise, if you're high enough.

Pretty high!

Bob is right, but you would have to get pretty high before your IAS cruise was at the IAS for best rate of climb. In fact, that would essentially define the service ceiling. (at least for your cruise RPM setting) Trim for best rate of climb, and climb until it won't climb any more - so you are essentially now cruising at IAS for best rate of climb. Certainly must be in the FL's right?

I would have to go back and look through my data to see where the cross-over speed is where flaps =0 and flaps = -3 would give same performance.

scsmith said:

Bob is right, but you would have to get pretty high before your IAS cruise was at the IAS for best rate of climb. In fact, that would essentially define the service ceiling. (at least for your cruise RPM setting) Trim for best rate of climb, and climb until it won't climb any more - so you are essentially now cruising at IAS for best rate of climb. Certainly must be in the FL's right?

I would have to go back and look through my data to see where the cross-over speed is where flaps =0 and flaps = -3 would give same performance.

Click to expand...

Steve, you da man (on a great team)! It's a beautiful wing on a beautiful ship... and after giving up my LS6b, that's saying a lot!

I've always felt that getting a QB wing was a great decision given the high quality of the riveting on the leading edge. Spent a fair amount of time pondering what kind of laminar flow characteristics the wing had. It's apparent to me that there are some significant effects but at the same time it's a total joy to maneuver and is tolerant of contaminants like rain and little bits of ice (not much!). (btw, intolerant = a PIK20b stalling during a pull-up into virga).

I have no stripes on the white wing but wish I had a patch of color to detect ice. I once picked up an invisible amount that was only detectable by airspeed loss. I rely on looking back at my red stabilizer for ice detection but Florida is the best fix.

I live on an obstructed, semi-rough grass field so all takeoffs are with a notch of flaps (not clear I could get out with 2, bags, full fuel and reflex flaps- not even an option). As a result all takeoffs on all surfaces are done with a notch just to stay consistent.

I climb at 133 knots and neutral flaps, dropping to 125 passing through 7 or 8k.

All cruising was done in reflex until recently. Now I've started playing with neutral flaps above 8k. Currently I'm subjectively thinking that the 'cross over' point for me is typically at 9 or 10k. I think all these figures are very loading dependent so YMMV.

Bill "I like flying on top of the convection now" Watson
N215TG - flying 5 years
aka Mauledriver, FourEyes (4i)