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Side slips in -7

uk_figs

uk_figs

Well Known Member
Friend
I have been practicing various approach techniques for short fields and find that sideslips to the right are difficult. Slips to the left are OK but seem to have high rudder forces. Trying to figure out if it is my technique or an aircraft thing so would appreciate any feedback from the experienced RV aviators on their technique.
Thanks
 
The RV's don't have a big dihedral effect - i.e. the rudder doesn't have a huge impact on bank angle or roll rate. I suspect this is a function of their short span.

Because of this, they require a disporportionate amount of rudder to offset a given bank angle in a slip.
 
I can't understand the problem

I fly my RV-6A tith two wing spans 24 feet and 21.5 feet I just bank it over and apply opposite rudder and slip down to the runway in either configuration. I usually go to the left because of the traffic patterns and I'm on the left and I can see better. I have the small RV-6 rudder. It is not difficult to fly sideways down the runway to burn off speed offering the side of the fuselage to the wind. That is the only time I use it (landing), which is almost every flight. You must be trying to do something more sophisticated than I am used to.

Bob Axsom
 
Guess I'm stating the obvious but....

get some altitude to go practice the slips. I was doing my BFR with a friend who happens to be a CFI. We'd went through the usual drills and everything going great. Having a good time practicing "falling leaf", etc.

We went into land and I was a little hot and started to do the usual slip. He suggested to be more aggressive with the rudder input. We did a T&G, climbed out and fortunately had gained some altitude while "jawing" about how much rudder was appropriate, etc. I told him to show me what he thought was appropriate and then we'd go try it down low again. Piper Super Cub amount of rudder and the -7A wanted to dip a wing rather quickly.....

So, just a reminder, preaching to the choir, stating the obvious, etc.... but ... Practice at altitude and if you're going to go with an CFI, make sure he understands the difference between a 152 and a RV....

Doug
 
Slips

I love to do slips in a Champ or similar craft but don't care to do them in my 6. I don't have any slip time in the counter balanced series so cant talk to the difference in rudder force required but, I think the force required is much more than I want to put on my airplane. If the speed is a bit on the high side that makes it worse. If the flaps are working I use them and am careful to be in the white arc.

Now, put me in a Champ and you can be sure I am going to slip it every time around and will likely perform a turning slip starting on downwind all the way around to final and I will push the rudder all the way to the firewall.
 
Our 7 slips just fine the rudder is a little on the heavy side compared to the other controls,but it just takes alittle practice to get the feel of it.we have the bigger rudder also.normaly if i am so high that i need to slip with flaps out i just go around ,its either or for me.
 
I think I know where Bill's going with his question. That big RV7/9 rudder can be tough to move if your airspeed is too high. Slow down first then slip to lose altitude.
 
Has anybody heard any issues of doing slips in an RV with full flaps? I have done it many times and found no ill tendancies but always think about the Cessnas that do not allow slips with full flaps.
 
I find it takes lot's of rudder pressure to do a full slip in my -9 above 70kts. I also don't consider a slip as effective in my -9 as it is in other type airplanes. I have a sort of 70kt unofficial full slip self imposed limitation right now as I still need to finish my flight testing.

Has anyone done cross-control stalls in their RV? I have yet to do one and will soon. It can be a handful in some airplanes and as I am only at 60 hours hobbs I want to wait a bit more.

I am curious How much (if any) stall speed increases in a full cross control.
 
plehrke said:
Has anybody heard any issues of doing slips in an RV with full flaps? I have done it many times and found no ill tendancies but always think about the Cessnas that do not allow slips with full flaps.
Click to expand...

I have done full flap slips in Cessnas (172's) and all you get is some elevator oscillation. It's not a big deal and there is no loss of control. I doubt an RV would have the same issue as the Cessna problem comes from the high wing masking the tail in the full flap full slip configuration. It's almost like a tail stall.
 
apkp777 said:
I have done full flap slips in Cessnas (172's) and all you get is some elevator oscillation. It's not a big deal and there is no loss of control. I doubt an RV would have the same issue as the Cessna problem comes from the high wing masking the tail in the full flap full slip configuration. It's almost like a tail stall.
Click to expand...

This phenomena was pertinent on Cessna aircraft before the "swept" vertical stabilizer came about. With the swept tail, there is not enough rudder authority for it to be a real problem. Don't try a steep slip with full flaps on a Cessna 170B. Been there, done that.
No problem with an RV.
 
Yeah, the -9 is totally fine with placing the rudder hard on the stop, power off.
 
Data Point

I found that even forward slips to counter a cross wind in my RV-6 needed more rudder pressure than I was used to in a C-172.

Jim Sharkey
 
apkp777 said:
Scott, what's the slowest you will slip at?
Click to expand...

The answer isn't really relevant (or safe) until anyone considering exercising such boundaries goes out to explore progressively at altitude.
With power off, the -9 has fantastic aileron control as you approach the stall in severe cross control. These boundaries make you smile when you consider Van's design.
 
Airspeed error.

I'm not sure flying to the numbers (ie. 65Kt.) is what you ought to be doing here.
You will notice that if you quickly release the rudder whilst in a side-slip there will be a marked change in IAS, which suggests to me that there is significant airspeed error whilst slipping an RV- and the amount probably dependant on your particular pitot/static setup. (How many builders have noticed that the static vent position is different on the fuse plans to that marked on the documentation accompanying the pitot/static kit.) You ought to be flying the aeroplane by feel as much as the ASI.

RVs do not delight in side-slipping with the panache of Tiger, Cub or Auster. You can do a left/right/left side-slip in the Tiger, after the flare, to wipe of the airspeed whilst flying level holding off for the landing. In my experience RVs do not lend themselves to this kind of manoeuvre, for what ever reason, and so I confine slide-slipping to above 500'. If I am still too high by then I'll go around.
Never forget that crossing the controls up at low speed is an excellent way to enter a spin.

I also suspect that Vans deliberately made the rudder forces high, to protect the Fin. Remember that unlike the wing and tailplane, the fin is asymmetric (it only sticks out one side) and so the rudder applies twisting forces to the Fin.

Now, this is only my personal style, but I confine side-slipping to above 500', mostly on base. I do NOT push on full rudder just because I can, I only apply what I feel is a reasonable load.
But I do enjoy a huge side-slip in the Auster, right through the flare and kicking it straight on touch down.

IMAO
Pete.
 
tc1234c said:
Full flap, maintain 70 kts.
Click to expand...

Dave's original post was concerning short field operations. If you try to land an RV-9A on my strip at 70 kts. you're going to float past the railroad at the far end of the strip. I use 60 kts. in my -6.
 
They're all different

If I am at 60 kts in my heavy short wing configuration RV-6A I am about ready to drive my struts into the ground past the tires.

Man this thread just goes and goes. A slip feels so natural I don't think of individual controls other than their natural function an non-slipping flight and they are all used at the same time as needed to keep from stalling and keep going in the right direction. I'm sure you can get in trouble with improper control usage but why would you do that? Don't mind me I'm just bumbling along here.

Bob Axsom
 
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Mel said:
Dave's original post was concerning short field operations. If you try to land an RV-9A on my strip at 70 kts. you're going to float past the railroad at the far end of the strip. I use 60 kts. in my -6.
Click to expand...

Yes, the original post is asking about short-field technique and the use of side slips. I really am not sure that in an RV-9 the two are compatible. To land short, I really have to "drag" it in at about 50kts over the fence. I wouldn't want to be in a slip anywhere near that.

If you slip down, assuming you slip at no less than 65-70 kts you won't be able to bleed off the excess speed and still land short. IMO a short-field approach should have a lower angle of decent. A steep angle and your going to land long, no matter how much you slip. If you have a C/S prop (as discussed in lot's of threads) it will help considerably.
 
Stalls in a slip

Considering stalls in a slip configuration, you shouldn't (I emphasize shouldn't) have any unusual yaw or spin tendency. It is possible that an airplane stall in a slip can actually self recover. Yeah, you may think I am crazy so I confirmed my opinion with the FAA and here's is their quote from the Airplane Flying Handbook "Unlike skids, however, if an airplane in a slip is made to stall, it displays very little of the yawing tendency that causes a skidding stall to develop into a spin. The airplane in a slip may do little more than tend to roll into a wings level attitude. In fact, in some airplanes stall characteristics may even be improved."

The problem for me is, you may have an airspeed error (as one posting suggested) and you could have a stall very close to the ground at a seemingly safe IAS.
 
apkp777 said:
Yes, the original post is asking about short-field technique and the use of side slips. I really am not sure that in an RV-9 the two are compatible. To land short, I really have to "drag" it in at about 50kts over the fence. I wouldn't want to be in a slip anywhere near that.

If you slip down, assuming you slip at no less than 65-70 kts you won't be able to bleed off the excess speed and still land short. IMO a short-field approach should have a lower angle of decent. A steep angle and your going to land long, no matter how much you slip. If you have a C/S prop (as discussed in lot's of threads) it will help considerably.
Click to expand...
I guess we'll have to agree to disagree on technique. I don't like dragging in, flat, with power. I fly the pattern at 70 kts. slowing to 60 kts. over the fence (at idle power) and have just enough energy to flare the -6. And that's with the 3-blade Catto prop. An RV-9 would float even at these speeds. I also have no problems slipping at 60 kts. if needed.
 
Mel said:
I guess we'll have to agree to disagree on technique. I don't like dragging in, flat, with power. I fly the pattern at 70 kts. slowing to 60 kts. over the fence (at idle power) and have just enough energy to flare the -6. And that's with the 3-blade Catto prop. An RV-9 would float even at these speeds. I also have no problems slipping at 60 kts. if needed.
Click to expand...

I don't disagree with you. I actually was taught (and teach myself) to always be able to glide to the runway in the event of an engine failure at all points in the traffic pattern (except upwind). A low approach doesn't lend well to that.

And most "short" fields really are that short. But for the purpose of describing technique it is importance to talk about a shallow power on approach.
 
apkp777 said:
Has anyone done cross-control stalls in their RV? I have yet to do one and will soon....I am curious How much (if any) stall speed increases in a full cross control.
Click to expand...

I don't know if all RV's behave like my RV-3 did, but in a full rudder slip, it would NOT stall with full aft stick. Many planes are like this, including my Pitts. It will not stall out of of a full slip, much less spin. You can stall out of a partial slip, but probably not a full slip. RV's are rudder limited, so you might as well use full rudder to get any value out of it. I was never very impressed with how effective slips were in RV's, but it is a way to fine tune your approach glide without making power changes.
 
Thanks for the feedback

As has been noted my question is primarily about the technique as it relates to short field operations. I agree with the poster about going around under normal conditions if too high as I have found it is not easy to force a -7 down with a FP prop.
Sometimes you do not have the option to come in flat or drag it in because of trees etc and I generally like to keep a reasonable speed safety margin so I am normally at about 85 mph on base to final and aim for 75 mph over the numbers. At these speeds with the flare and ground effect I end up using about 1100 feet with minimal brakes on a hard surface runway.
As some of the fly-ins I would like to attend are 2000+ft grass strips with trees on the approach I would like to be able to consistently fly a somewhat steeper approach with the same speeds, hence my original question.
 
Dave,

I only have 75 hours in an RV and thought I had a handle on how to fly one. I had a friend (Jeff Point experienced -6 flyer) fly my -9 the other day and he came in like he would do in -6, really high and tight. I actually said to him "Jeff, you will never make this landing, you're gonna have to go around", His response was, "let's see about that". He laid in a picture perfect slip, dropped us like we were on an elevator and touched down mid-field on a 3k ft runway, rolled to a stop with ample to spare and after wiping the smile off my face, told him "incredible". Now, I am trying to do the same.

Keep working it and you'll have that think landing on a dime.
 
Safe Speeds on Approach with/without slip

We are not all using the same pitots and we are not all using the same static installations and we are not all using the same airspeed instruments so it is a given that the speeds reported by individuals should not be taken as accurate for any other individual airplane. And, of course, it varies with weight.

Slipping increases sink rate - that is why we do it. But you want to ensure that while you are doing it you maintain sufficient airspeed for safety. You are trying to push the envelope a little, but how do you know where the edge of the envelope is at that moment?

The above paragraphs lead me to conclude that a good, sensitive AOA meter is the right way to do that stuff. I won't explain all that here except to say that the stall is always where the AOA says it will be, no matter what the ASI says. Even in a slip.

And yes, I agree that you can land shorter if you are power-on, slower than your minimum sink speed, otherwise sometimes known as the back of the power curve. The idea of slipping in that configuration is just scary, IMHO. I find this difficult to do because the RV is so powerful that it is hard to use power without using too much power. This technique was very easy in a PA-28, C-150, 152, 172.
 
Check Idle speed

uk_figs said:
As has been noted my question is primarily about the technique as it relates to short field operations. I agree with the poster about going around under normal conditions if too high as I have found it is not easy to force a -7 down with a FP prop.
Sometimes you do not have the option to come in flat or drag it in because of trees etc and I generally like to keep a reasonable speed safety margin so I am normally at about 85 mph on base to final and aim for 75 mph over the numbers. At these speeds with the flare and ground effect I end up using about 1100 feet with minimal brakes on a hard surface runway.
As some of the fly-ins I would like to attend are 2000+ft grass strips with trees on the approach I would like to be able to consistently fly a somewhat steeper approach with the same speeds, hence my original question.
Click to expand...

One thing you might want to check is the idle speed of your engine. On the ground, not moving, closed throttle, fully warmed up engine. Best to do this after a flight to ensure engine fully warm.

You should set the idle speed as low as possible, say 400 or 450. Even if it idles roughly at that speed. Remember that when airborne, the airflow is "assisting" the idle speed, and the prop won't idle at 400 while on final at say 70 kt. But it will really reduce the "float" and rollout during landing.

And even though the idle stop is set at 400, you don't have to idle the engine at that speed on the ground. Just add a tiny bit of throttle and idle at whatever RPM you like.
 
AoA

Interesting point on the AoA being accurate even in a slip, I do have the Dynon AoA setup and the betty voice alert but I have to admit the AoA display on the D100 is not well integrated into my normal scan pattern yet.I suspect the light bar repeater on the dash that I have seen mentioned here would be more obvious on short final and I have thought about adding this capability.
I have my voice alert set for the mid yellow range which would give some margin, as it is I tend to get a tank 1 fuel low voice alert in the left slip config which does not go over well with the spouse:D
 
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Big Oops!

When I said an AOA would be accurate in a slip I was thinking of the designs that have separate, two port sensors or a pivoting vane. Mine is the LRI.

The GRT, Dynon, etc. which calculate the angle from the airspeed and pitch may not be accurate during a slip for the same reason that your ASI may not be accurate during a slip: you may not get accurate sensing from the static and maybe even not from the pitot. Another theory blown up. Darn. The angle of attack, if correctly computed, would still be the best way to control slow flight, in or not in a slip.

I know there must be someone out there with both who could do the comparison. Hint.
 
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