[born2fly]

Like lots of folks, I have trouble slowing down my RV6. I have to pull back to 8-10" to get down to flap speeds, and my shock-cool warning goes off regularly. When I can finally get the flaps down (100kts for half), I get some serious drag, and I can feed some throttle back in. The only other choice is starting to slow down 25 miles out - which I do but I don't like it. Thought about speed brakes, but what a chore to install!!!

What I'd LIKE to do is put the flaps out earlier, like maybe at 120kts - but I'm concerned about busting something. Does anybody know:
> What's the weakest part of the flap system?
> What can be done to deploy flaps at higher speeds safely?

Thanks,
G.

 

[PCHunt]

Flight Techniques

A couple of flight techniques you might want to try:

After slowing to 130 or 140, pull the nose up and climb (while the power is reduced). After a couple or three hundred feet, you should be slow.

Do a steep turn, say 45 to 60 degrees, and pull some G's, say 1.7 to 2 G's. That will also slow you down.

If you try to slow down in a descent, it will take forever.

 

[Geico266]

I'm not sure shock cooling would be a factor in the pattern. You are slowing down from cruise anyway, and the throttle should be at a much lower power setting than cruise so you are cooling the engine off to begin with. 100knts for flap speed seems high to me, I thought is was like 80MPH.

What kind of cooling alarm do you have? What are it's parameters and who set them?

 

[Mel]

PLEASE do not exceed maximum flap speeds recommended by Van. The flaps carry more load than any other control surface. They are the only control surfaces that are pulled into the airstream and stay there.

 

[L.Adamson]

100knts for flap speed seems high to me, I thought is was like 80MPH.

My Van's RV6 builders manual lists 110 mph for 20 degrees of flap & 100 mph for full 40 degree flaps.

110 mph = 95.59 knots

L.Adamson

 

[plehrke]

I to have my alarm on my EDM-700 go off in the pattern if not carefull. Typically it will be when I am doing touch and goes as you go from full power take-off/climb and then bring the power back on downwind and I pass the 60 deg/min cooling set in the EDM-700 defaults. I typically do just as PCHunt suggests a steep turn to base to bleed off speed or a short climb on down wind to keep from over cooling the cylinders by bring back too much throttle.

I would also suggest refraining from trying to increase the flap speed. Use pilot technique instead.

 

[PCHunt]

Actually, when I suggested a steep turn, I would do this before entering the pattern, a few miles from the airport, to dissipate energy.

I do NOT recommend 2-G turns from downwind to base!!!!

 

[Kahuna]

I did a night formation departure on the wing this year and it was not until my lead was pulling away from me on departure 130kts that I knew something was wrong(remember I have a 6cyl, he was a 4 cyl.). I went to route (took spacing) and immediately, duh, flaps are down. So my full flaps are good to 130kias at least once. I have not repeated it. I also have the hex rod installed.

I typically drop 15 degrees at 130kias to get the drag chute going if I come blasting into the pattern. Works well for me. I try to come in high and fast for safety (ok fun too) where I desire to drop flaps some to get slowed down quicker.

My experience in my plane only.
Shame on me for not checking, shame on him (Speedy) for not catching it on the position and hold.(Part of his job before we launch).
Best,

 

[Mike_ExpressCT]

Just remember the cardinal rule: You can go down or you can slow down, but you can't do both!

Like many say, it's probably going to be an exercise of just thinking ahead a little more. Don't worry, you'll figure it out, just start to slow down sooner than you think you need to.

 

[flyeyes]

I typically drop 15 degrees at 130kias to get the drag chute going if I come blasting into the pattern.

Hi Mike, I don't want to be rude, but you might want to think this one through.

Are the flaps stock on your "Super 8?"I recall that there are some areas of pretty significant beef-up

Someone more knowledgable than me can interject here (cough..Kevin../cough) but it is my understanding that the aerodynamic force on the flaps increases with the third power of speed.

This means that if the flaps are designed for 95 knots at partial extension (per Van) then 130 knots is about a 2.5x overload.

I understand that the limits are probably conservative, and that the (non-hex) flap rod has been shown to be the weak point, at least on -6s, but repetitive loading this high may not be a good thing.

 

[born2fly]

update

Thanks for all the replies - - -

Yeah, I do know about "thinking early" - but that also means slowing down way early - at RHV, I usually have to reduce power at 16-20 miles out, and I'm descending only from 3000'. So, I'd really like to make more/earlier use of the flaps in speed management. But it's very clear from lots of posts that exceeding flap speeds is a bit of a no-no. I use 100kts/115mph for 10-degrees, then wait for 90/104 for adding more. By the time the second 10 degrees comes in, the drag slows me down where I need to be.

My JPI is the cooling alarm, probably a little conservative... but in any event, I hate pulling from 19-22" back to 9-10" in any short interval.

I'll have to check my actuator rods (round or hex) and see what I've got, but I have no illusions that it'll make my flaps good for 120kts. Incidentally, I also have "goofed" a couple of times and found myself at 120kts with takeoff flaps (10 deg). Just 'cause I got away with it doesn't mean it's okay tho.

G.

 

[flyeyes]

Thanks for all the replies - - -

(snip)I usually have to reduce power at 16-20 miles out, (snip)

My JPI is the cooling alarm, probably a little conservative... but in any event, I hate pulling from 19-22" back to 9-10" in any short interval.

What are you doing with the mixture? When you have good instrumentation (which I assume the JPI is, but I haven't used any of their products for a lot of years) it is surprising how much mixture has to do with CHT.

If you were taught, as I was in the '70s, to reduce power, push the nose over, and go rich for the descent, this is a recipe for rapid cylinder cooling.

At typical descent power settings (i.e. below 60% power) you can't hurt the engine with the mixture--if you stay closer to peak EGT, you can keep the cylinders warmer at a lower power setting.

I may have missed it, but what kind of prop do you have? I'm used to a CS RV8, but I don't find a need for exceeding Van's flap speeds, and I typically enter the 45 at 120-140 KIAS. I have flown a couple of FP RVs, but 16-20 miles seems like a really long way out.

 

[Bob Axsom]

I just pull the nose up

As I approach the airport I just pull the nose up bleed off airspeed until the indicator hits the top of the white arc and go to full flaps. I don't try to finese the flaps except for the electric transition delay, they are full up or full down. When I'm coming in on final and I'm still high in order to keep the speed down I put it in a slip, as hard as necessary and as long as necessary to get rid of the excess altitude and onto the desired glide slope. It is not a big deal and I would not even begin to consider adding speed brakes.

Bob Axsom

 

[Kevin Horton]

So my full flaps are good to 130kias at least once. I have not repeated it. I also have the hex rod installed.

That's an interesting data point, but I would be more concerned about eventual fatigue failure from multiple events than I would be about a static strength issue.

...it is my understanding that the aerodynamic force on the flaps increases with the third power of speed.

In general, at a constant angle of attack, aerodynamic forces would increase with the square of the speed. But, in level flight, the angle of attack decreases as we go faster. I think that at a constant speed, the loads on the flap would decrease a bit as the angle of attack decreases (this is a SWAG, so it could be wrong). Thus I believe that as we accelerate in level flight, the loads would increase at maybe a tiny bit less than the square of the speed. But, if we are at high power (as in Mike's event reported above), the blast from the prop wash would probably increase the loads on the flaps.

It is really hard to know what the weak link is in the flap system. I hope none of us ever finds out. If anyone chooses to deploy the flaps at speeds higher than Van recommends, I hope they will do frequent inspections of all parts of the flap system. Hopefully there would be signs of distress before a failure actually occurs.

 

[Bubblehead]

my technique from the Mooney days

The Mooney 231 and 201 I used to fly were slick like RVs and you had to plan ahead to not shock cool the engine (or turbo) and be down to flap and gear speed. Here's how I learned to do it back then and it works fine for RVs too.

Slow the prop down a few hundred rpm, then reduce power 3" of mp every minute, let the nose drop, and trim for a 500 fpm descent rate. Descend to about 200 feet below pattern altitude. By this time you should be at your pattern power setting. Then raise the nose to bleed off the excess speed as you return to pattern altitude, and start dropping flaps. I use 20 degrees for most landings but can do 30 or 40 or 10 or none if conditions warrant. Then trim for airspeed (80 kts is what I use on downwind), bring prop speed back up and add power to control the descent rate.

The cruise descent means each minute is 1000 feet loss of altitude and a distance traveled of 2 nm at 120 kts or 2.5 nm at 150 kts. I usually use 3 nm to make the math easy and it generally works out great. With those numbers it's easy to use the "Distance To" portion of your GPS to plan the descent. 16miles out would be fine for 5000 feet of altitude change. Or use the "Time To Next" to compute the number of minutes at 500 fpm to get down.
The key is to make small (3") power reductions far enough out to not have to rush it at the end.

 

[Kahuna]

Hi Mike, I don't want to be rude, but you might want to think this one through.

Are the flaps stock on your "Super 8?"I recall that there are some areas of pretty significant beef-up

Someone more knowledgable than me can interject here (cough..Kevin../cough) but it is my understanding that the aerodynamic force on the flaps increases with the third power of speed.

This means that if the flaps are designed for 95 knots at partial extension (per Van) then 130 knots is about a 2.5x overload.

I understand that the limits are probably conservative, and that the (non-hex) flap rod has been shown to be the weak point, at least on -6s, but repetitive loading this high may not be a good thing.

There are no areas of any beef up on the Super 8.
If the drag of the flaps is any indication of the force applied to them at any given speed, a notch at 130 is no where near the force of full at 100. Restated, the drag of 15deg at 130, is no where near the drag of full flaps at 100. Just my swag based on power settings.

And your not being rude.

Best,

 

[SportAvServ]

Shock cooling?

Hey there Born.
I have always thought that shock cooling was over rated, if you ar at 10k and reduce the power a lot and come down at a high rate of speed for 10 minutes, yes I would concern myself about shock cooling. If it is just in the pattern when you reduce power to get it slowed down I don't see how it could hurt anything. Just think about all of the 172's Cherokees and Grummans that have had hundreds of simulated engine failures and easly make it to TBO. The difference is, that they didn't have a little light that tells them they are doing something wrong.
If you want to know what loads are put on your flaps go find someone with an RV-4 with manual flaps. My first RV was a 4 and I wouldn't try to put the flaps down untill I got below 80KIAS, 70 is better. At 90Kt's I felt like I was going to break the lever and it twisted so much from the force that it didn't want to catch the detent and lock. I am a CFI and do check people out in RV's and one of the problems some have is just getting it slowed down. Two things, first get to pattern altitude sooner to give yourself more time, second, don't be afraid to reduce the power to idle if necessary. If you have a constant speed prop it will slow you down in a hurry, especialy if your making a 2g turn and reducing power. Don't do that in a pattern unless you have practiced it at altitude. If you have a fixed pitch you just need to learn how to mannage the extra slipperyness.

Happy tail winds.

 

[justinmg]

If you are at speed, can a touch of aileron and opposite rudder be used to drag the airframe a bit. Just a bit. I`m sure a boot full wont be good for the tail.

 

[logansc]

If you're at a non-towered airport, traffic permits, and the locals don't mind, just run the runway at an altitude lower than pattern altitude (how much lower, is your call or SOP/whatever...). Halfway down the runway or when your downwind interval permits, pull up in a climbing turn to downwind. Throttle back when you are half way up to pattern altitude and prop to the stop. After 180 degrees of turn to the downwind, you'll end up at around 80 mph (in an RV) even if you run the runway at cruise speeds+.

If your airport community/situation won't tolerate that, then do as one other suggested. Instead of leveling off at pattern altitude, level off 200' or so low. Use your excess energy to pull up to pattern altitude bringing the throttle back at the same time. Once slow, prop forward/flaps down/done deal.

At my field, we have a mix of experienced pilots and some inexperienced, but enthusiastic new guys including quite a few who've come to GA late in their lives. They have a tendency to fly quite wide and long on downwind but they are a great part of our local "mix". We love'em. The guys who've been around awhile usually get in and get on the ground and stay out of their way. Scan the pattern very carefully inbound, know where everyone is and you can use these techniques to get into the pattern at high RV cruise and and even higher let-down speeds and yet slow right down to flap/landing speed in literally just a few seconds. No fuss.

Ciao!


Lee...

 

[David-aviator]

If you're at a non-towered airport, traffic permits, and the locals don't mind, just run the runway at an altitude lower than pattern altitude (how much lower, is your call or SOP/whatever...). Halfway down the runway or when your downwind interval permits, pull up in a climbing turn to downwind......

Or do a standard over head military approach without the pull up. The tower guys around here don't have a problem with it, traffic permitting, just ask. Lots of energy can be lost in the 180 degree turn to downwind. I can come across our runway break point from initial at 150-160 knots and roll out on down wind at 90.

Beyond that, there isn't an airplane in the world that won't slow up in level flight with reduced power, pull the throttle back in a timely manner and fly the airplane. None of this is rocket science, its learning how fly a high performance airplane and staying ahead of it, not 10 miles behind it. It is not a good idea to exceed the flap speed of any airplane - they all have a pad but at some point the flaps will be flapping at the trailing edge of the wing and that would be interesting.

If your Lyc can't take the heat loss with a power reduction, get a Subaru - the Merlin sound is much more pleasing anyhow.

 

[Rick6a]

Like lots of folks, I have trouble slowing down my RV6........

Frankly, I don't get it. How much time do you have logged in your RV? I don't mean to downplay your obvious concerns but I can only respond based upon my experience. My fixed pitch equipped RV is plenty fast and slippery and I often cross mid field wide open, often at or near 200 MPH before pulling the throttle and then turning downwind. The speed seems to decay well enough and somewhere along base, the speed hovers right around max flap deployment speed at which time I crank in just a hint of flaps, then the speed really comes down. It isn't very long after that before full flaps are deployed. I tend to fly a tighter pattern than some of the spam can drivers around here and honestly.....slowing down hasn't been an issue since I became reasonably comfortable with the plane's basic handling.....after about 20 hours of PIC time or so.

 

[SvingenB]

If your Lyc can't take the heat loss with a power reduction, get a Subaru - the Merlin sound is much more pleasing anyhow.

I am a bit puzled about this shock cooling Going high and fast, throttling to idle and descending real fast for some time, yes - maybe. But when speed is reduced when power is reduced I just can't imagine the engine will be in any danger of being shock cooled.

 

[Norman CYYJ]

Frankly, I don't get it. How much time do you have logged in your RV? I don't mean to downplay your obvious concerns but I can only respond based upon my experience. My fixed pitch equipped RV is plenty fast and slippery and I often cross mid field wide open, often at or near 200 MPH before pulling the throttle and then turning downwind. The speed seems to decay well enough and somewhere along base, the speed hovers right around max flap deployment speed at which time I crank in just a hint of flaps, then the speed really comes down. It isn't very long after that before full flaps are deployed. I tend to fly a tighter pattern than some of the spam can drivers around here and honestly.....slowing down hasn't been an issue since I became reasonably comfortable with the plane's basic handling.....after about 20 hours of PIC time or so.

I agree 100%

 

[John Clark]

Shock cooling?

If shock cooling is a real concern, what about shock heating? You taxi out, do a short run-up and blast off, What is the rate of temperature change during the takeoff and initial climb? I think that shock cooling is mostly myth. With reasonable transitions between power settings it is a non-issue. I have taken three big Continentals beyond TBO by following John Deakin's advice on how to treat engines. Here is a link;

http://www.avweb.com/news/pelican/183094-1.html

John Clark
RV8 N18U "Sunshine"
KSBA

 

[L.Adamson]

Frankly, I don't get it. How much time do you have logged in your RV? I don't mean to downplay your obvious concerns but I can only respond based upon my experience. My fixed pitch equipped RV is plenty fast and slippery and I often cross mid field wide open, often at or near 200 MPH before pulling the throttle and then turning downwind. The speed seems to decay well enough and somewhere along base, the speed hovers right around max flap deployment speed at which time I crank in just a hint of flaps, then the speed really comes down. It isn't very long after that before full flaps are deployed. I tend to fly a tighter pattern than some of the spam can drivers around here and honestly.....slowing down hasn't been an issue since I became reasonably comfortable with the plane's basic handling.....after about 20 hours of PIC time or so.

We've got a lot of RV's around here, with both fixed and C/S props. As far as I'm concerned, it's still like day & night, when it comes pattern speed management between the two types of props. It's not even close...

L.Adamson

 

[Dennis Madden]

By definition you shock cool the engine every time you shut down... ;-)
Rut oh...
DM

If shock cooling is a real concern, what about shock heating? You taxi out, do a short run-up and blast off, What is the rate of temperature change during the takeoff and initial climb? I think that shock cooling is mostly myth. With reasonable transitions between power settings it is a non-issue. I have taken three big Continentals beyond TBO by following John Deakin's advice on how to treat engines. Here is a link;

http://www.avweb.com/news/pelican/183094-1.html

John Clark
RV8 N18U "Sunshine"
KSBA

 

[tin man]

FWIW i too have a problem slowing down my RV. RV3, Fixed pitch, 1st notch flaps @ 100mph, 2nd notch @ 80 mph, numbers @ 60. I've been at it for a while, 2000+ rv hours and have to plan my descent and slow down accordingly. I would be very wary of anyone who brags about entering a pattern wide open and 200+ mph. IMO that person is putting not only himself but others in the pattern at risk. I don't think it's wise to exceed Vans flap speeds even if others have lived to talk about it.
Happy flying
Tom

 

[Rick6a]

FWIW i too have a problem slowing down my RV. RV3, .......I would be very wary of anyone who brags about entering a pattern wide open and 200+ mph. IMO that person is putting not only himself but others in the pattern at risk......Tom

Tom,

Your concerns are misguided and border on the misinformed. Is it "bragging" to state facts and experiences...facts and experiences others know to be true? Exactly how in your opinion are others put at risk? You know nothing of local airport conditions and radio communication habits to paint with so broad a brush. I've never flown a -3 yet can easily imagine with its much narrower profile, slowing down can be more difficult, but for you to suppose the "wide body" series of side by side RV's share the exact same characteristic as your -3 is unrealistic.

 

[kentb]

Tom, I agree...

I would be very wary of anyone who brags about entering a pattern wide open and 200+ mph. IMO that person is putting not only himself but others in the pattern at risk. I don't think it's wise to exceed Vans flap speeds even if others have lived to talk about it.
Happy flying
Tom

Yes, all kinds of non-standard things can be done, but it is not the safest thing to do. If the airport is clear of other traffic, then do what ever makes you happy, but I don't know anyone that can ever be sure that there isn't some other traffic out there. Unless they have a real good connection with the man-up-stairs.

Kent

 

[David-aviator]

Perhaps the problem is a misunderstanding of what is standard and what is non standard.

AIM and the FAR's do not attempt to set air speed limits except to say the max speed below 10,000' is 250 knots and 200 knots when within 4 nm of an airport within Class B or C airspace. There are no other limits. So what is standard or non standard in the typical flying day of an RV pilot?

It is difficult to legislate common sense but the answer really is "excercise common sense" and fly with caution. If a traffic pattern is full of Cessnas practising landings with cross country legs, the RV pilot needs to excercise patience and common sense. It is not the time or place to come ripping into the pattern at 180 knots with the trainers 100 knots slower. Slow down early and join the parade. If the pattern is really huge with 4 mile spacing, negotiate a short approach but do communicate and as per FAR, do not endanger other aircraft.

If the pattern is empty, speed is at the pilots discretion. An overhead approach is legitimate and an option, there's a diagram of it in AIM. But again, communicate your intentions.

The question was about using flaps at higher than recommended speeds to facilitate a close in speed reduction. The obvious book answer is no.

I will say this about flap limit speeds though, they are not all the same. By that I mean there is a structural limit for 40 degrees and it is not the same as for 10 degrees, that only makes sense. The limit we have obviously is for full flaps as it is not qualified any other way. That being the case, I do not have a problem with setting 10 degrees when 10 knots high to facilitate a speed reduction. But I won't set 40 flaps at plus 10 knots. In fact I never use 40 for normal ops.

This is personal technique and not recommended for anyone but me.

 

[Paul Thomas]

Good post David. The only thing I'd add is that the only time you can feel some sort of confidence that the pattern is empty is at towered fields, but even there you might have a NORDO trying to come in.

 

[born2fly]

Not a lot of help yet....

Frankly, I don't get it. How much time do you have logged in your RV? I don't mean to downplay your obvious concerns but I can only respond based upon my experience. My fixed pitch equipped RV is plenty fast and slippery and I often cross mid field wide open, often at or near 200 MPH before pulling the throttle and then turning downwind.

First thing is, I don't have the balls to come into a pattern at my crowded airport at 200mph. So I need to be at trainer-speed 3 miles out and 1500' AGL. To do this, I can EITHER:
Start 10-12 miles out reducing power to ~14"
Yank the throttle at 4 miles and hold the nose up

In level flight, it takes more than a few miles to go from 165kts to 80kts just by pulling back to 14". This is a simple truth and is my basic gripe. RVs are SLICK! (Never had this problem with my old Cherokee...)

Yes, I have a CS prop and it helps. Yes, I've tried climbing a bit and I don't like the technique plus, unless I climb about 500-1000', it doesn't cut the speed quickly.

Maybe I just need to get used to pulling the throttle back into my pocket, that actually does slow the puppy down.

grumble grumble

 

[hecilopter]

Suggestion

When 3 to 4 miles out from the airport, pull power to around 20" or so and roll into a right or left 60 degree bank, 360 degree turn. Pulling G will slow you WAY down. Then adjust power as needed to merge into the pattern.