[Kyle Boatright]

For those of you who are adept at short field work in your RV's, what speed do you use over the threshold and what are your typical landing distances on a hard surface using medium braking?

Today, I was practicing short field landings. The airplane was at about 1300 lbs including fuel and me, and I was coming over the numbers at 58 or60 knots indicated, then flaring and floating for a couple hundred feet. The float issue is due to my high pitched wood prop (wood prop = relatively fast idle ~700 rpm).

I'm hesitant to go much below 60 knots on short final, simply because a gust could make for a thumper of a landing.

In the end, with medium/light braking, the flare, float, and roll-out were taking about 1,000'. Harder braking could have reduced that some, but even after 500 hours in type, I'm not a good enough (or brave enough) pilot to make the 300' landings Van has demonstrated on video. I figure harder braking and a C/S prop would help, but how much better should I be able to do on a consistant basis with my set-up?

Thoughts?

By the way, with one notch of flaps, the takeoffs were easily under 400'.

 

[Kevin Horton]

For those of you who are adept at short field work in your RV's, what speed do you use over the threshold and what are your typical landing distances on a hard surface using medium braking?

Speed comparisons are meaningless unless everyone knows how much error their airspeed system has, and they report speeds in CAS, rather than IAS. There could easily be more than 5 kt error in the IAS, between ASI instrument error, and static system position error.

You need to fly the speeds that work for you, in your aircraft.

 

[pierre smith]

Me too

Hi Kyle,
My results just about mirror yours. I have come in at 70 MPH, close to your 60 knots and still have a little float and 1000' is usually the result. On a calm day, you can decrease the speed by 2 or 3 knots and see how much float you have. It will definitely reduce it. Do it incrementally until you find what Kahuna called "the splat" landing......just enough airspeed as you drag it in with throttle......get over the threshold, cut the power and "splat" in a three-pointer braking fairly hard. You'll get it under 1000 feet but beware of doing this on gusty days.......accelerated stalls, y'know.

Regards,

 

[JonJay]

"Splat Landings"

That was all I ever did when I first started flying my CS equipped 6. Full flaps, over the numbers at 75mph, splat, done in 500ft or under. I started uping my airspeed to 80mph, but still, if timing was not perfect, splat, landing over, with a little more rollout. Not too smooth, but safe and the airplane was done flying.
I have now adjusted my normal landings to less than full flaps, 80mph, and have a much more consistent gentle touchdown and still less than 1000' rollout. If I want short field, full flaps, drop it to 75mph, splat, landing over....
My neighbor with a fixed pitch wood prop comes in much slower and still has a much more significant roll out. Van's 7 I transitioned in, fixed pitch, floated a lot more. The CS prop seems to make a big difference.

By the way, I do not "drag" with power. All landings are power at idle, prefferably before turning base. That is how I was trained. Make the field.

 

[John Clark]

Vref

Speed comparisons are meaningless unless everyone knows how much error their airspeed system has, and they report speeds in CAS, rather than IAS. There could easily be more than 5 kt error in the IAS, between ASI instrument error, and static system position error.

You need to fly the speeds that work for you, in your aircraft.

Kevin is right, the indicated numbers can be meaningless for comparison with another aircraft. My solution would be to go out and do a little airwork. Stall the airplane in the landing configuration and note the reading. Now you have a baseline to work with. Conventional logic is 1.3 times that number for approach, with some slowing "over the fence."

John Clark
RV8 N18U "Sunshine"
KSBA

 

[David-aviator]

......Thoughts?

By the way, with one notch of flaps, the takeoffs were easily under 400'.

Perhaps the Navy way of carrier landings is best - lots of power, lots of drag and plop you are there and hope the hook catches the cable.

Seems the most important aspect of a safe short field landing is knowing the stall speed and flying just above it with power. The only way to know that speed is to demonstate it at altitude. Seems to me my beast stalls at 56 KIAS with 20 flaps. I use 70 for final and flare and have had no problem with a 2200' runway, most times getting stopped in about half of it. The problem with plopping in a trike is the nose gear - that's asking for trouble - IMHO. There's no way of keeping the NG light with that technique.

 

[Kevin Horton]

Kevin is right, the indicated numbers can be meaningless for comparison with another aircraft. My solution would be to go out and do a little airwork. Stall the airplane in the landing configuration and note the reading. Now you have a baseline to work with. Conventional logic is 1.3 times that number for approach, with some slowing "over the fence."

Many aircraft have significant airspeed system errors at low speed. A landing reference speed (Vref) of 1.3 times the stall speed only provides the expected margin from the stall if it is based on calibrated airspeeds. I.e multiply the CAS at the stall by 1.3, and then fly at this CAS. Many airspeed systems under read at the stall. If the IAS at the stall is multiplied by 1.3, one may be much closer to the stall than expected. For example, the POH for the Cessna 182Q that I fly once in a while says the max weight, aft CG landing configuration stall is at 50 KCAS or 38 KIAS. If we fly at 1.3 times 38 KIAS, that is 49 KIAS. The position error chart says that 49 KIAS = 55 KCAS, or 1.1 times the stall speed. Anyone who tried to fly an approach at 49 KIAS would likely get a nasty surprise when they tried to flare.

It is quite unlikely that very many amateur-built aircraft owners have the means to determine the calibrated airspeed at the stall. So there is no practical way to determine an approach speed that is 1.3 times the CAS at the stall. What is a fellow to do? I recommend the following, based on the flight tests that are used to determine minimum safe approach speeds for both light aircraft and transport category aircraft:

1. Fly the aircraft enough to have developed a consistent normal approach technique.
   
2. Ballast the aircraft to max landing weight at forward CG. Make sure the ballast is well secured.
   
3. Climb to a safe altitude, and conduct a series of simulated approaches and landing flares, using the same technique as you would use in a real approach and landing. Reduce the simulated approach speed by a knot or two each time. Note the aircraft controlability at the approach speed, and note the ability to flare. Note the minimum speed where the aircraft has satisfactory characteristics.
4. Pick a day with very light winds and no turbulence or wind gusts. The best time to find such conditions is right after sunrise, but even then there may be several weeks between days with suitable conditions. Be patient. Don't risk a hard landing by doing these tests on a day with gusts or turbulence.
5. Fly a series of approach and landings, using your normal approach and landing technique, but reducing the approach speed by a knot or two each time. Pay attention to how the aircraft responds to the flight control inputs in the flare. Note any signs of inadequate control, impending stall, difficulty in obtaining a satisfactory touchdown, etc. As you reduce the approach speed, eventually the aircraft will start talking to you. It will tell you that you shouldn't reduce the approach speed any further, or you will risk a hard landing, etc.
6. Caution - Don't be too aggressive about trying to demonstrate the absolute minimum possible speed. This path leads to a hard landing, and possible aircraft damage. Stop the investigation when you have a slow minimum speed that allows an acceptable flare and touchdown, using your normal technique.
7. The following restrictions, from the requirements for type-certificate aircraft, are recommended to ensure that a minimum speed approach and landing demonstration is not a "party trick":
   • Once the power has been brought to idle, there should be no need to increase the power. By all means, if you need to increase power to achieve a safe touchdown, increase the power. But you should conclude that perhaps the approach speed was too low, and the minimum approach speed should be increased.
   • The power changes that are made should be the same as would be made during a normal approach and landing. E.g, if a normal approach and landing has the power brought to idle in the flare, it should be possible to do the same during the demonstration of the minimum approach speed.
8. Add a comfortable increment (perhaps 5 kt) to this minimum demonstrated approach speed, and this becomes your minimum operational approach speed, to only be used in calm conditions. If the conditions are not smooth, add a few more knots, so that as the airspeed bounces around in the bumps, the bottom of the bounces is no lower than your minimum operational approach speed.
9. Confirm the ability to safely manoeuvre at your minimum operational approach speed by conducting turns at that speed at a bank angle that is a bit higher than the highest you would use in service. You should be able to maintain a stabilized turn without encountering stall warning. Increase the minimum operational approach speed if required to obtain satisfactory manoeuvring capability.
10. If you have a short field landing technique that differs from your normal landing technique (perhaps you keep power on until touchdown, and use a minimal flare, etc), repeat the above series of tests using a short field technique. You may have different minimum approach speeds for normal and short field landings.

 

[hevansrv7a]

Additional Thoughts

I took some ribbing and pitying looks, but I put in a Lift Reserve Indicator. I don't care what the CAS airspeed is and indeed, it will vary with load and density altitude. I know where minimum sink is and I know where stall is and these are very precisely indicated. Link to LRI on my site. The back of the power curve is between them.

I don't mess with it much, but I found that getting on the back of the power required curve and adding a little power ("dragging") keeps airspeed low, nose up (-A model). Full flaps, of course. This calls for delicate power changes because the RV is so powerful it can pop you out of the curve and speed you up if you overdo it. Of course, you really don't want to lose power while doing this!

 

[JonJay]

I took some ribbing and pitying looks, but I put in a Lift Reserve Indicator. I don't care what the CAS airspeed is and indeed, it will vary with load and density altitude. I know where minimum sink is and I know where stall is and these are very precisely indicated. Link to LRI on my site. The back of the power curve is between them.

I don't mess with it much, but I found that getting on the back of the power required curve and adding a little power ("dragging") keeps airspeed low, nose up (-A model). Full flaps, of course. This calls for delicate power changes because the RV is so powerful it can pop you out of the curve and speed you up if you overdo it. Of course, you really don't want to lose power while doing this!

I am told the "old time" instructors would not check you out until you could do power off stall, short field, and wheel landings, all power off. I think we are lucky to have such reliable engines now but I consider dragging in with power still to be bad technique, even though it is a commonly taught and used. I am sure it is safe, maybe even safe in some conditions like gusty winds, I just dont prefer to do it. Of course, after all that practice, if I do lose an engine with my CS prop, it will not be the same as power off idle. I will be training for that next, up high, over a good long runway.