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RV-8 Aft C of G landings. Advice please

Ian Findlay

I'm New Here
My RV8 has the heavy IO 360A1B6 200 hp engine and heavy Hartzell CS prop.
Empty weight is 1111 lbs and empty C of G is 77.17.

My weight is 200 lbs and solo I fly with 30 lbs ballast in rear baggage floor to avoid running out of elevator control during flare (round out) from a full flap steep approach into our short sod strip. (solo landings are tidy)

This ballast, and full back stick, also prevents tail lifting and therefore prop damage during engine run up that can happen in a very fwd. C of G configuration if pilot is careless.

A question of long time owners: It is very rare for me to carry a passenger and with far aft (but within limits) landings I have made some far less than pretty arrivals.
Fifty odd years ago I was taught full stall landings and no "wheelers"
Perhaps this has returned to bite me as it seems that the RV8 cannot be "stalled on" because the tail wheel touches before the stall occurs.

My solution, tested today, is to securely ballast the passengers seat to get C of G legally well aft and to use a slightly higher approach speed AND use a ?wheeler? tail high landing attitude. This was much tidier! Comment please?

Ian Findlay. From Downunder.
 
Ian,
You nailed it?
I experimented with my -8 by adding sand ballast until I reached 250 lbs. Each additional sack of sand required a different approach speed. This has been the biggest challenge in learning how to fly her. I have found that with a little bit of speed, she will wheel land fine even with a large passenger. If you blow the wheel landing, just convert to a three-pointer. The nice thing about hauling around the sand is that the sacks of sand don?t razz you for a lousy landing? 
 
MY RV8 was almost identical to yours, 200HP with the CS Prop. I also carried ballast in the back, a 7 gal water container which allowed me to just pour the weight on the ground if I was taking a passenger. I learned quickly that the 8 does not like 3 point landings just as you described. After a few months I started doing all landings on the mains. You will need this skill for crosswind landings anyway. The only good reason I know for three point landings is short field landings.

Pat
 
It sounds to me like you have it figured out Ian. I only have a little over a thousand hours flying the -8, and as I've said many times, I just get more consistent landings if I aim for a slightly tail low wheel landing. If I am trying for an ultimate short field landing, I'll three-point, but as you have discovered, it is NOT stalled in the three-point attitude - it is a three-wheel landing, and you have to fly it on perfectly. If you want a "full-stall" touchdown, then it will be tail first, and the mains will arrive with a resounding thud.

The stick forces on the RV-8 with an aft CG are very light, and as the airplane slows down, they get even lighter, going to zero (and some will swear they reverse....swearign becomes common in that condition). This means that with an aft CG and low speeds, the airplane wants to "over flair" and bang the tail down if you are not 100% prepared for it.

It is very common for new RV-8 pilots to makes some very bad (and surprised) landings when they first start carrying passengers. What happens is that they fly what has become a "normal" approach for them, which is fine for forward CG's, but a little slow for aft CG's. With a Constant Speed prop, the airplane is decelerating rapidly with the engine at idle. So as they come over the threshold with the power at idle and the Cg aft, the stick forces get lighter and lighter - then they go to flair, and suddenly do a tail-stand. Adding a little power as you cross over the fence will make the stick feel a lot better.

Personally, I avoid very short fields with an aft CG - it is just a very critical flying task to get it to turn out right.

Hopefully, this helps you to understand what's happening, and that you're not alone or unique - aft CG's are more difficult in the -8, and wheel landings are generally the easiest way to bring the -8 back to earth consistently. Yes, you can three-point it, and many do. But you have to adapt landing techniques to both aircraft and conditions, and do what is necessary to make good arrivals.

Paul
 
Landing the RV-8

Good write up Paul. And to think, builders are still asking where to put the battery in an I0360/Hartzell equipped RV-8................ Go figure! Pat carries seven gallons of water ballast. I carry a tool kit, and installed the ELT under the Vertical Stabilizer.

I had a RV-8A guy at the Pecan Plantation fly-in tell me he has 53 pounds of lead in the tail of his RV-8A to make it balance. I ask him: Where did you put the battery? On the firewall of course! Then I said: If you are going to carry lead in the back of your RV-8A to balance it, should it not generate electricity for you?

Maybe the readers will put this thread together with the: "Where to put the battery", thread on the same page, and come to some kind of understanding on how one effects the other...............or not!
 
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The -8 I fly is 1162 and 78.4 empty - which converts to 80.3 when I'm solo. This is a 200hp/CS Hartzel airplane with the battery in back (of course).

I flew with and without ballast in the baggage compartment and now just leave it out (I like to fly light as possible). I simply got used to the limited elevator. I fly power off, 180 degree approaches from abeam the end of the runway on downwind. It is not unusual to find me bumping off the "up" elevator stop while in the turn (due to the steep bank angle), but once it's wings level again I find that I have enough to round out and make a nice wheel landing. There certainly is not a surplus of elevator in this condition, but it is safe and managable in this (particular) airplane. Also, the "out" if I run out of elevator completely is simply adding a little power - it responds instantly.

Adding a passenger simply means adding about 5 knots to the approach speed and using less nose up trim.

Finally, as Paul has stated, the -8 is tough to 3 point. It will do it, but the speed bleeds off so fast in the 3 point attitude that your timing has to be spot on. I've done some very nice 3 points, but most were accidents.
 
squirrely 3-pters

I was a dyed-in-the-wool 3-pter. I quickly got good at wheel landing the -8, especially with a passenger, just as many others here have advised.

Then, I set about to try to understand why the -8 was hard to 3-pt. The obvious first-blush answer is that the 3-pt attitude is not the stall attitude. But that's true of the -7 also, and I found that much easier to 3-pt. So, I don't have a better answer (yet).

One thing I have observed that gives a very squirrely feeling to 3-pters in the -8 is that even if you squeak one on just perfect, it then is still very light on its feet for a while, and small gusts, or bumps on the runway, or whatever, kind of throw it back in the air. It just feels really "loose" on the ground. I think that this is because the inboard portion of the wing is stalled, but the outboard portion is still flying very well.

There have been some folks that have mounted curved triangular strakes on the fuselage near the wing leading edge, and report that 3-pters are slower and feel more solid. This may well be. It keeps the inboard portion of the wing flying too, so the lift is more evenly distributed. You are landing slower for the same 3-pt angle of attack, so the effect of a small gust or bump is less. Thats my theory anyway.

Bottom line, wheelies make more high-confidence landings.
 
Ian Findlay

Thank you all who contributed to this thread. There is a wealth of experience and skill out there being contributed to this interesting thread.
Please keep it coming.

Ian
Albany WA.
 
...It is very common for new RV-8 pilots to makes some very bad (and surprised) landings when they first start carrying passengers. What happens is that they fly what has become a "normal" approach for them, which is fine for forward CG's, but a little slow for aft CG's. With a Constant Speed prop, the airplane is decelerating rapidly with the engine at idle. So as they come over the threshold with the power at idle and the Cg aft, the stick forces get lighter and lighter - then they go to flair, and suddenly do a tail-stand. Adding a little power as you cross over the fence will make the stick feel a lot better...

This is a good, informative discussion that helps salve my wounded ego a bit. In my extensive 60 hours of RV-8 flying experience, I've only had a passenger with me on three occasions. My wife, my son, and then my wife again. The first two landings with passengers were not much different from my ballast test flights -- wheel landings that just naturally transitioned to three-pointers.

However, I took my bride up last week for a quickie and returned in time to beat the sunset. I was a little faster than normal on approach, and there was a 10-knot crosswind. With our short, narrow runway, I made the absolute WORST landing of my life. She, of course, was oblivious in the back seat. I was deflated.

It's good to read that others share my frustrations.
 
Nice discussion and it's been discussed before but I have a question for you guys.

First a little background, I fly off of what some would call a short strip, 2,400 of manicured grass and rarely use more than 1,200 when landing and a lot less if I get on the brakes but that gets expensive. Pax or solo doesn't seem to make a lot of difference in distance, maybe 100 feet.

The one thing I have noticed is wheel landings are much easier with about half flaps. So much so that I rarely use more than half unless I'm a bit high, even then I'll retract to half on short final. If I'm in the mood to try a three point I find it a bit easier with full flaps and can get it stopped a bit shorter but not by much. Mostly though, it's a wheel landing, hold the tail up till it stops flying which is surprisingly slow then hold it down after it touches. Brakes as needed but usually not till the tail is on the ground.

So, my question is, what are you guys doing with the flaps? Just for the sake of the discussion, let's assume no wind. Do you find it easier with half flaps for one technique over the other?
 
John...

We fly off a 525m (1650'?) strip, that with obstructions / slope, is effectively more like 350m (1100'?) useable. So in there it is 3 point, full flap - if you land it in the right place don't need the brakes :)

Prior coming here, I was only initially taught 3 pointers, and those were fine dual (which was the more usual config) and more difficult solo. Once taught wheelers, I find them easier solo, and use them especially for X-Winds / hard runways. Dual I'll still use them, but they are trickier to avoid it skipping (due CG).

Flaps - 3 pointers tend to be full always. Wheelers, I reckon easier half flap, or even no flap.

My conclusions:
1. Try not to be "3 point" or "wheeler" biased - if you prefer one, work on the other until they are both options... they each have their uses.
2. Short Field landings NB the effect of power (I make a teaching point on famils / convexes of recovering from the incipient stall with a small amount of power... then ask the quesiton "and the reverse?" i.e. taking off power at low speed can stall the aircraft in itself). Until familiar with this, come in with enough speed not to worry about it.
3. Think CG! If you typically fly solo or dual, refresh the technique you'll need when you do the other.
4. I think there is some merit in John's point about less flap on a wheeler, esp in a X-Wind - keeps rudder more effective?

Andy
RV-8 G-HILZ
 
Use of flaps

It's probably because I few a Grumman AA1-A "Yankee" for twenty three years that I always land with no flaps or full flaps. The Yankee's flaps were small and provided little drag, but they did add some useful lift. In addition, full flaps helped lower the deck angle, which improved visibility, and lowered induced drag in the little two seater. There was really no point in using partial flaps with the Yankee.

Flying the Doll, I quickly learned that I could handle her just like the Yankee. I could even use the same numbers in the pattern. Of course the RV-8 has large and effective flaps, and it is not necessary to use full flaps all the time. But, the larger power to weight ratio of the Doll allowed me to make very short takeoffs with full flaps. I could climb out with no sag as the flaps motored up from full down. The Doll would just keep accelerating and climbing out.

Landing became routine using the same full flap setting each time, and like the Yankee the deck angle was reduced and speed control on final was easier to achieve. Just my .02
 
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