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Safe flap speeds

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Skydivnqt

I'm New Here
Hi all.
I have a friend that bought a -9a from the builder at 40.1 hours. I am a CFI working with him on instrument stuff the -9a and he tells me he uses 80kts for flap speed. Looking at his POH it states "87kts maximum full flaps speed" and the owner is just using 80 to have some margin (a hint to his conservative flying style). Yes his GRT glass and backup steam gauges are both in kts. He is having trouble getting slowed down on instrument approaches. He can manage if he starts to slow about 3-4 miles before starting down the hill and just flies the entire procedure below flap speed but once starting downhill he is not yet comfortable with the maneuvers needed to slow to flap speeds while on a glideslope.

I have been scouring the net to see if there is an intermediate speed for a partial flap setting such as something like 0°-10° maximum 110kts then 10°-20° 100kts before just getting to a full flap speed of 87kts. I find the RV-7 has something along these lines of a graduated flap speeds but it is a different wing than the -9. This is a straight forward, no mods -9a build.

Is there any kind of a partial flap speed setting that has been found/calculated/tested by others that we could consider or is the -9a really just the single speed setting for all flap positions? I understand that each is experimental and has its own limitations but at the same time they should all be pretty similar in their limitations.


Thanks guys

Shaun
 
My POH (from original builder) indicates 96 kts as max speed for 20° flaps, and 80 kts as max speed for full flaps. I have since decided that it works best for me to enter the pattern at 90 knots and deploy 10°, then go to 20°abeam the numbers at 80 kts, and full flaps on final approach at 70 kts. I have as CS prop, so I can slow down faster than with a fixed-pitch.
 
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I pretty much do the same as MacCool. I get to about 95 or so and drop the first notch and use the rest as needed to get stabilized at 70 on final.
 
From the Van’s construction manual.

i-GDjtvgb-L.jpg


So for the -9/9As, the flap limit speeds are 100 MPH up to 15 degrees, and 90 MPH to full flaps (32 degrees). Convert to knots if required.

If you and/or the owner don’t have one, get one here —> https://store.vansaircraft.com/rv-9-9a-usb-flash-drive-plans-manual-fd-plans-rv-9-9a.html

Oh yeah, Vne is in TAS, not IAS (although you won’t find that in the construction manual, unfortunately).
 
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If you don’t have a constant speed prop, your approach might look a little different. I have an RV6, O-360, fixed pitch Sensenich GA prop. If I pull the throttle to idle mid field downwind at a slowed up speed of about 135 KIAS, I’ll need to extend the downwind to make a dead stick no flaps landing from there. So I use flaps to control that so that I don’t have an extended pattern. First notch (20* - I have manual flaps) can be extended at up to 95K if I want. I usually wait for about 87 KIAS. Full flaps usually comes out at about 75K. At a higher airspeed (87K) full flaps is a little difficult for me with manual flaps.
If you have trouble getting slowed and stabilized, you can try half flaps at 95K and use a forward slip to get the descent path and speed you are looking for, and then extend full flaps when stabilized. Extending flaps at 95 adds lift, and not a whole lot of drag, so plan accordingly, especially with a fixed pitch prop. Once you get your airspeed below 75K it will come down much more quickly, especially with full flaps no matter what prop you have.
 
Scott Hersha said:
If you don’t have a constant speed prop, your approach might look a little different. I have an RV6, O-360, fixed pitch Sensenich GA prop. If I pull the throttle to idle mid field downwind at a slowed up speed of about 135 KIAS, I’ll need to extend the downwind to make a dead stick no flaps landing from there. So I use flaps to control that so that I don’t have an extended pattern. First notch (20* - I have manual flaps) can be extended at up to 95K if I want. I usually wait for about 87 KIAS. Full flaps usually comes out at about 75K. At a higher airspeed (87K) full flaps is a little difficult for me with manual flaps.
If you have trouble getting slowed and stabilized, you can try half flaps at 95K and use a forward slip to get the descent path and speed you are looking for, and then extend full flaps when stabilized. Extending flaps at 95 adds lift, and not a whole lot of drag, so plan accordingly, especially with a fixed pitch prop. Once you get your airspeed below 75K it will come down much more quickly, especially with full flaps no matter what prop you have.
Click to expand...

The guy’s flying a -9A. Are you suggesting he fly faster than the Van’s flap placard speeds?
 
With AOA

In my 9A, with constant speed prop, my pattern is at 1.3 Vs1, which is 54 Kts. Using the AOA, I fly the pattern at 63 (roughly).
For instrument approaches I fly to the FAF at 90. At that point I apply 10 degrees flaps. At about 1 mile from the Runway I pull the power to begin slowing to around 63 and add another 10 degrees of flaps.
Most of my instrument approaches to landing are at 20 degrees. Rarely do I put out all 30 degrees. But, I am always flying into paved runways that are at least 3000 feet. Never had a problem getting it down and stopping.
(will admit I've never landed in the rain, which would impact the braking).

If I were to deploy full 30 degrees flaps my plane stalls at 45 Kts indicated.
 
A 9A flies very differently with a constant speed prop than it does with a fixed pitch prop. Without the big brake out front it takes a little more planning to slow it down. The 87kt (100mph) flap speed is a doable speed to start the slow down. Don’t deploy full flaps there. Make that your 10* flap speed. Incremental 10* flap movements can come after that with whatever markers deemed necessary in the instrument approach.

As for the standard VFR pattern approach, I am looking to be at the 100mph (87kt) mark and putting in 10* of flaps abeam the numbers. Turning base I will put in 10* more. Once on final its full flaps as needed. Of course all speeds after initial deployment will be below that 100mph (87kt) speed.
 
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My uncontrolled home airport has two 7000’ x 150’ runways. It’s easy to get casual about landing technique. And depending on the wind, the shorter I land the more I have to taxi. It’s an abundance of riches, and one has to guard against complacency in landing technique. Some landings and some wind conditions mean flying over a lot of concrete if one wants to avoid two miles of taxiing to the hangar. Lots of room for creativity in trying to stay sharp, a blessing, and a curse.
 
Good stuff, thanks guys.

MacCool, would you happen to know where your builder got the 96kts @ 20° number for your POH? That speed would give some flexibility and make things much easier.

It looks like what we have in the current POH is already incorrect according to what Carl posted. If ours shows 87kts as max full and the Vans construction manual shows 100smph and 90smph then converted that is 87kts to 15° and 78kts max for full flaps, we are already operating over the speed according to that info.
 
RV8JD said:
The guy’s flying a -9A. Are you suggesting he fly faster than the Van’s flap placard speeds?
Click to expand...

Of course not. I was merely suggesting what I do in my RV6 as a possible solution. I don’t have an RV9 manual, so I don’t know what Vans suggest as a maximum flap extension speed. He said his POH says max FULL flap speed is 87 KIAS, but who wrote the POH? My POH says 87 KIAS max flaps also, but I wrote it and it’s not binding, or required. Van says I can extend the first notch of flaps at 110 mph (95 K). I choose to use 87 as my upper limit. If Van says the upper limit for an RV9 is 87K, then that should be respected, and it sounds like it is. In fact the OP says he is using 80 as an upper limit, similar to what I do (7 knots below max). It just takes a little more planning to get down to your flap speed.
 
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Here is yet another option for pattern work. I am not instrument rated but have 1000 hours on my fixed pitch RV9A. My technique for entering the pattern is to pull power halfway out and begin slowing down while on a 3-mile 45-degree entry. Downwind check completed, I then pull back and raise the nose and trim it nose high. This allows the hershey bar wing to create drag and she slows down very quickly. I fly downwind at 75kts and drop half flaps. When making my turn to base leg I drop full flaps and decrease speed to about 70Kts. Upon turn to final, I slow to about 62-65kts. For me this eliminates floating upon flair. The 9 will float a lot with excess speed. I also begin my turn to final halfway into my base leg as to gently round the arch to final. (my way of being conscious of stall spin issues on final turn). If I may suggest, go to altitude and find out what indicated airspeed you stall at clean and with full flaps. This will help build a bit of confidence on the low end. My 9 stalls clean at about 49kts and 42 with full flaps. You are going to really enjoy this airplane once you build a bit of confidence with it. Best of Luck!

Steve Koziol
Dues Paid
N424JK 1000 hrs.
RV 9A
 
Skydivnqt said:
Good stuff, thanks guys.

MacCool, would you happen to know where your builder got the 96kts @ 20° number for your POH? That speed would give some flexibility and make things much easier.

It looks like what we have in the current POH is already incorrect according to what Carl posted. If ours shows 87kts as max full and the Vans construction manual shows 100smph and 90smph then converted that is 87kts to 15° and 78kts max for full flaps, we are already operating over the speed according to that info.
Click to expand...

No…no idea how he came up with 97 kts / 20°. I’ve never met him…I bought it from the guy that bought it from him. 90 kts works fine for me, though….with a CS prop, speed management isn’t really a problem. As I approach the pattern, once I’m at pattern altitude, I pull it back to 15 inches and 2300 RPM. That gets me to 90 kts pretty much right now. This -9A is the most predictable and responsive airplane I can ever remember flying. I’m a big fan of constant speed props on it.
 
Scott Hersha said:
Guess I should have read post 5.
Click to expand...

Scott, Sorry if you thought I was picking on you, I didn’t intend that.

My concern is that the OP who is new to the RV-9A, and maybe Experimentals in general, is looking for solid guidance on flap limit speeds. Some of the RV-9 guys start rattling off numbers that bear no resemblance to Van’s published numbers. I would venture to guess that many of those numbers were picked either incorrectly or because they were convenient, with no structural analysis validation, modifications, or testing to back them up.

As you know, Van’s flap limit speeds are structural design speeds, and only Van’s knows how much margin there is. And the folks who put in hex actuating rods to increase the strength thinking that is enough beefup to allow higher flap limit speeds are not taking the rest of the flap structure or actuating system into account.

Another scary part are folks purchasing an RV with a “POH” sometimes take the speeds (and weights) in the POH at face value and never question the numbers or bother to check them against Van’s published numbers.

Again, just trying to make sure the OP knows what Van’s published numbers are, and hopefully he will use those numbers and not just pick some numbers “because the speed would offer some flexibility and make things easier”.

I wish Van’s would have bothered to step in and comment.
 
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RV8JD said:
Scott, Sorry if you thought I was picking on you, I didn’t intend that.

My concern is that the OP who is new to the RV-9A, and maybe Experimentals in general, is looking for solid guidance on flap limit speeds. Some of the RV-9 guys start rattling off numbers that bear no resemblance to Van’s published numbers. I would venture to guess that many of those numbers were picked either incorrectly or because they were convenient, with no structural analysis validation, modifications, or testing to back them up.

As you know, Van’s flap limit speeds are structural design speeds, and only Van’s knows how much margin there is. And the folks who put in hex actuating rods to increase the strength thinking that is enough beefup to allow higher flap limit speeds are not taking the rest of the flap structure or actuating system into account.

Another scary part are folks purchasing an RV with a “POH” sometimes take the speeds (and weights) in the POH at face value and never question the numbers or bother to check them against Van’s published numbers.

Again, just trying to make sure the OP knows what Van’s published numbers are, and hopefully he will use those numbers and not just pick some numbers “because the speed would offer some flexibility and make things easier”.

I wish Van’s would have bothered to step in and comment.
Click to expand...

Carl, how about a link to those "published numbers"?
 
MacCool said:
Carl, how about a link to those "published numbers"?
Click to expand...

As Carl noted above, See post #5 above, which in turn come from vans builders manual. For other non builders out there, every owner really should have one and read thru it regardless of whether they are builders or non builders. Lots of good, “official” info in there.
 
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Skydivnqt said:
Hi all.
I have a friend that bought a -9a from the builder at 40.1 hours. I am a CFI working with him on instrument stuff the -9a and he tells me he uses 80kts for flap speed. Looking at his POH it states "87kts maximum full flaps speed" and the owner is just using 80 to have some margin (a hint to his conservative flying style). Yes his GRT glass and backup steam gauges are both in kts. He is having trouble getting slowed down on instrument approaches. He can manage if he starts to slow about 3-4 miles before starting down the hill and just flies the entire procedure below flap speed but once starting downhill he is not yet comfortable with the maneuvers needed to slow to flap speeds while on a glideslope.

I have been scouring the net to see if there is an intermediate speed for a partial flap setting such as something like 0°-10° maximum 110kts then 10°-20° 100kts before just getting to a full flap speed of 87kts. I find the RV-7 has something along these lines of a graduated flap speeds but it is a different wing than the -9. This is a straight forward, no mods -9a build.

Is there any kind of a partial flap speed setting that has been found/calculated/tested by others that we could consider or is the -9a really just the single speed setting for all flap positions? I understand that each is experimental and has its own limitations but at the same time they should all be pretty similar in their limitations.


Thanks guys

Shaun
Click to expand...

Shaun,

I know you were asking flap speeds, but you may be interested to hear how RV owners actually fly IFR and the config that they use. IMHO way different that shooting approaches in a 172 or Warrior.

Ex, I find that the airspeed varies too much getting bounced down final holding the glideslope. I prefer to shoot for 90KTs, no flaps in my FP 9A. I use pitch for speed and power for alt. At minimums I make any changes in configuration for landing.

Before I get flamed, here is my logic. If I were to shoot an actual approach to 200’ minimums, I am probably using an airport with a sufficiently long runway that will allow me to goto idle and burn off the necessary energy with or without flaps. The reality is I am on the ground on days that have minimums like that. More realistic approaches for me are the 1000-500’ circling GPS minimums at the smaller airports around me. That is plenty of time to slow down and configure the airplane to my liking.
 
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