CamTom12
Registered User
Huntsville, AL
EDIT: Fixed the links
Last edited:
Thats well and good. But, if you’re having to look at that airspeed instrument while landing at that “short mountain strip”, you are very apt to fail.
It doesn’t take very long to fly by feeling what the plane is telling you. Go to altitude, slow the airplane in landing configuration until it is hanging on that fine edge prior to the stall. Maintain altitude with a bit of power. You want to have the speed such that ANY increase in pitch or bank or reduction of power will precipitate a stall buffet.
Now, fly the airplane around, maintaining altitude, on that fine edge, at altitude, maneuvering (which will require slight added power to prevent a stall), but all the while hanging right on that fine edge.
While doing this in a Cub, more than likely the airspeed instrument will be pegged on zero. But the airplane will be talking to you all the while. And, feeling what the airplane is telling you will permit you to SAFELY land at that short mountain strip.
Trust me, it won’t take long playing the true slow flight game at altitude before you’ll develop a good feel for the plane.
But, Frankly, an airspeed indicator in a Cub is over rated as to its utility. So forget about CAS vs IAS and go fly the airplane and feel it’s paces.
I agree with you Mike, Another way is over a large relatively flat area with no obstructions like trees or power lines. A mile each way is a great size to start with....the trick is to stay within 5 to maybe 10 feet of the ground higher to start then lower as you gain some experience and confidence. At 5 feet or less if you stall one wing or the other wing or both wings or the tail all that will happen is you will touch down, your not high enough to get a wing tip into the dirt or the nose to fall enough to get the prop....fly around with power behind the curve,,,,it will give you a much quicker “feel” for the speed and feel and sight picture....as you gain more time and experience you can make shallow turns and practice holding it off with power with the nose high,full flaps just don’t climb out of ground effect or high enough to get a wing tip. Even if everything went wrong if your close to the ground the deflection angle is so low that damage would be minimal....getting comfortable close to the ground is the first step towards landing short unimproved places. If you still are looking at the airspeed to tell you it’s close to a stall you haven’t practiced enough to go where the airplane is capable of taking you on even 8:50 let alone 31s.
ps:
your airspeed will be reading zero or awfully close to it but you really don’t have time or altitude to look just like in the real world of bush flying
So I went up yesterday and did an hour or two flying around at MCA. I'm finding that without power and full flaps my cub just starts mushing around 38mph IAS and goes into a 800fpm descent. There is no real stall. Without flaps the same thing happens at about 41mph.
But if I add power to about 2000rpm I can maintain altitude and get the speed way down into low 30s IAS (off the scale on my AI so not exact.) I'm guessing this is because the power gives more airflow over the elevator and so more authority.
Which got me thinking about adding a burst of power during the flare after a slow approach to make sure elevator maintains authority (and prevent dropping in with a thud). I had always thought a bit of power was about slowing the rate of descent, but I can see that maintaining elevator authority is important too.
How do you guys do it for short field landings? No power, a short burst of power, or a steady rpm of say 1300-1500 into the flare? I'm thinking of the technique for short strips, not long comfortable ones. And I'm aware that I'll have to watch the nose pulling up and to the right if I add power.
Most instructors have little experience in either realm. Choose a really good aerobatics instructor,
There's one thing that bothers me. Let's say my IAS at stall is 38mph, and my CAS at stall is 44 mph. Given that the big error in IAS is very close to the stall, which number - IAS or CAS - should I be using for 1.3Vs, 1.2Vs and other approach speeds?
I have been using 1.3Vs IAS on base and 1.2 Vs IAS for final. That gives me approx 50mph IAS for base and 45mph IAS on final.
But if the IAS/CAS error at 50mph is much less than at stall, my 50 mph IAS may actually be close to 50mph CAS which is only 1.15Vs.
Here's what Imeson says: "If the pilot goes out and stalls the airplane, noting the indicated airspeed and multiplies this value by 1.3 (for approach) there is an error introduced into the equation that will result in the approach being made at too slow an approach speed."
He then goes on to suggest, though he is not totally clear on the subject, that the IAS should be converted to CAS and then multiplied by 1.3. In my case that would give more like 55mph on base and 50mph on final which is significantly different.
I.A.S. (MPH) | C.A.S. (MPH) |
50 | 58 |
60 | 66 |
70 | 75 |
80 | 83 |
Try closing the throttle all the way and just gliding in. It works well...At about 1,500rpm a little above MCA the approach is pretty straightforward but far too flat. I'm going to try somewhere in the 1,200rpm range with small adjustments to stabilize the approach.