lml@lancaironline.net Mailing List Archive

I am a LOBO instructor. I own and fly a Lancair IV-P.

I am also a sailplane instructor.

This discussion reminds me of one in the sailplane community talking about deploying full spoilers and being able to flare properly. It was thoroughly debunked there as it should be here.

The issue is carrying enough energy in the form of airspeed to arrest the rate of descent without going below the stall speed.

There is no question in my mind that the IV-P with gear down, flaps down, engine stopped and spoilers fully extended can carry enough energy to arrest the rate of descent (flare). 120 knots will be more than enough. I have landed my IV-P with full spoilers, gear and flaps down. 95 knots is plenty of airspeed to arrest the descent in this configuration with the engine as pulled back as I can get it. I doubt a truly dead engine will add as much more drag as the full spoilers.

Gliding at 120 knots with a stall speed is in the range of 75 knots is a differential of 45 knots. This is enough to climb a few hundred feet much less arrest the rate of descent. Work out the physics and you can see how much altitude you gain for converting this much horizontal speed to vertical speed. In sailplanes we expect about an 800 foot altitude gain in a pull up from 135 knots to 60 knots. Possibly a surprise to people here is that a Lancair will not be much different. It is energy conversion not drag that matters.

One thing discussed in the these emails is adding gear, flaps, spoilers late in the approach just before touchdown. I think that making these configuration changes late in the approach is a recipe for disaster. A 45 knot airspeed margin is likely not enough energy to overcome the configuration change and still flare properly. I think this is the point Randy is trying to make, but, it is not clear in his discussion.

After an engine failure my suggestion is to establish a stable descent at a constant airspeed of 100 to 120 knots (best glide or slightly above it), constant configuration and then flare normally upon reaching the ground. Put the gear and flaps down if you have time (height) to establish a stable descent after that. If not leave them alone. You can use the flaps for glide path control with the caveat that you should not retract them in the final 300 feet of descent. (Extending them further is fine.)

From: Bill Kennedy [mailto:bill_kennedy_3@hotmail.com]
Sent: Wednesday, January 27, 2010 5:47 AM
To: lml@lancaironline.net
Subject: RE: [LML] Engine out gear down Issue/The procedure! This was a wake up call for me...

I've had two occasions to land my large tail LNC2 without engine power, plus lots of idle power practice landings. I've never had any trouble with the round out. I think my speed was 80KIAS on the real engine outs, and slower on the practice landings. I don't understand why anyone would use over 100 KIAS for a forced landing. 1.3 X Vs0 aught to give any Lancair plenty of energy to round out in any power setting. What am I missing?

To: lml@lancaironline.net
Date: Tue, 26 Jan 2010 11:10:28 -0500
From: randylsnarr@yahoo.com
Subject: [LML] Engine out gear down Issue/The procedure! This was a wake up call for me...

All/ Gary,
Good points,
The extra 15 - 20 knots is what you give away dropping gear and flaps transitioning from best glide profile to landing configuration with a dead engine.

My point is that when you are done gliding (at 120mph) and ready to touch down, the extra energy is necessary if you intend to drop gear and flaps to touchdown .
If a landing is being attempted with no gear, 100 or even 80-90 mph is good to ground effect, bleed off speed and land on the belly. I am with you there.

If you have your 120 mph glide and drop the gear at 500 or 1000 feet AGL you are not going to be able to arrest the decent at the ground. I was shocked to find this out and almost broke my airplane learning this lesson. It is absolutely true and it scares me that many, including myself are cruising slow (100kts) and low (pattern altitude) dragging gear and flaps with partial power.
Loss of power at that poing is much much worse than I and ( I believe) most of us realize!!!

Before understanding this a little better, in an engine out situation, I would have set up for best glide at around 120 mph, find a reasonable spot to land, drop the gear at 500- 1000 ft AGL and put it down. This works for a Cessna 150 or 172. For a Lancair the first part is right the second is DEADLY WRONG....Everyone should try this at a very safe altitude. It is shocking! I had no idea this was the case!!!

Set up best glide at 120 MPH or 106 kts 1000 feet above your imaginary ground level with absolutely no power (flat idle), descend to 500 ft above your imaginary ground level and drop the gear (flaps if you like) . You are now slowed to 85-90 mph dragging the wheels and descending at 1000 feet per minute or more. Do this to your imaginary ground level, try to flair the airplane and you blow right through it in a 1000 to 1500 feet per minute decent!!! No kidding. Try and be aggressive with back elevator to make it flair and you will stall and could easily turn it over. TRY THIS ONLY AT A VERY SAFE ALTITUDE! We are so used to a little power on approach that we really never experience this until a real emergency happens. Remember it is dramatically worse with a totally dead engine as you have a huge increase in prop drag.

I believe the procedure should be best glide speed ( I like Gary's 120 MPH) and then pickup the extra 15-20 knots to short final and drop the gear and flaps and touch down in the last 10 seconds before the gear/ flap drag bleed off the extra 10 -15 knots. You do not want to fly any longer than 10 -15 seconds with a dead engine and gear extended. Not because the airplane wont fly that way, it will. It is because after those 15-20- extra knots are gone, you can not arrest the decent at the ground. That was totally foreign to my thinking before this. With the gear down you can not descend steep enough to pick up enough speed to flair at the ground. Yikes!

A local Legacy driver and friend explained what he learned when initially practicing engine out landings in the Legacy.
He started his simulations with 160 kts IAS downwind in the pattern (gear and flaps up). After 4 attempts pulling the power and trying to fly different variations of tight patterns dropping gear and flaps in various places he came to the following conclusion:
The only way to get his Legacy on the ground safely from a complete engine failure in the pattern was to IMMEDIATELY turn and dive for the end of the runway holding around 135 knots and dropping the gear/flaps only at short final. He said it feels like a very radical move but it is the only way. He has thousands of hours of HP airplane time and is very experience in the Legacy. He admitted he grotesquely over estimated the airplanes ability to make the runway with NO power. He went on to say that few realize the dramatic flight characteristic change from low power to no power. You loose the small amount of thrust and add a TON of drag. Each time he turned sooner and tighter. He also said he would have bought it if he had to do it for real had he not practiced it several times to truly understand what it takes to get it down. The story spooked me enough to prove it was true in my 235/320 and he is absolutely right.

This is important, our Lancair's absolutely with not round out at the bottom with no running engine with gear and flaps down, again unless you have the precious 15-20 knots extra energy used at the very last moments as it goes quickly with wheels down. You trade that extra energy for the flair. No extra speed no flair...

I believe all high performance airplanes share this behavior to one degree or another. I also strongly believe engine out landings can be done successfully if we better understand how our airplanes fly with a dead engine and execute the right emergency procedures.

IMHO...
Sorry for ranting...

I would very much like to hear from the LOBO fliers on this subject. I am sure this has come up in the training.

Randy Snarr
N694RS
N235/320

--- On Sun, 1/24/10, Gary Edwards <gary21sn@hotmail.com> wrote:

From: Gary Edwards <gary21sn@hotmail.com>
Subject: [LML] Re: Airspeed sensing switch /Auto gear extension / Engine out gear down Issue!
To: lml@lancaironline.net
Date: Sunday, January 24, 2010, 4:07 PM

That is good info for everyone.

However, in my 235, 120 MPH is the best glide speed. That equates to 104 knots. I do not want to be going any faster in event of an off field landing, and most likely, I will leave the gear up in that situation. On a runway, I would use the gear, but unless it is a long runway, I will also keep the speed not in excess. Any speed above about 80 MPH results is a bounced landing and significant nose high attitude with the chance of dragging the rudder, and wasted runway behind me.

Also, a thought in reference to when to drop the gear. 7 to 10 seconds is fine if the plane still has electrical. But if the dump valve has to be used, that will not be enough time to get the gear down, especially if the pilot has to crab the plane one or two directions to lock each or both mains in place. The pilot is going to be a "busy beaver" in the last 30 seconds of flight.

Gary Edwards

LNC2

----- Original Message -----

From: randy snarr

To: lml@lancaironline.net

Sent: Saturday, January 23, 2010 12:20 PM

Subject: [LML] Airspeed sensing switch /Auto gear extension / Engine out gear down Issue!

Terrence,
Mine is the same as yours only no auto gear down. Only a warning light and horn for low speed and gear up.

I would seriously consider changing your set up for the following reason. This is a bit of a long winded response but it brings up a vitally important point for the group.

Gear and flaps down too early with a dead engine will have disasterous consequences every time.

With loss of power, gear and flaps should stay up keeping speed above 120 kts IAS until the last seconds before landing. My gear down is a count to 7. Everyone should know how many seconds it takes to get it down and locked as you will only have one shot to get it right in an emergency. You wont' be able to do that with your gear set up.

Many Lancair drivers (myself included until recently) have no idea that these how bad these airplanes glide dragging the gear with a windmilling propeller.

That is a deadly mistake. Dragging gear and flaps, you need a steep nose down attitude to keep the airspeed at a safe speed. Unfortunately, in that regime you can not flair the airplane. When you try to flair without a little power these airplanes just slow down and hit the ground. The situation is much worse if you are heavy.

This is very important for every Lancair driver to understand,

With a dead engine if the gear and flaps are down too early (anything sooner than 10 seconds before ground contact) the incident will most likely have a tragic outcome. This is absolutely true.

I don't mean to preach but I believe we would still have some good friends with us if we all understood this better. We recently had a fatal crash at my field where an experienced instructor died in a 210 in a similar circumstance which got me thinking about this.

The ONLY way to get down safely on your wheels in our airplanes is to keep and extra 15 or 20 KTS of energy (over a typical approach) all the way to ground effect and then drop the gear and flaps and bleed off speed and touch down. That extra energy is used quickly extending the wheels and you will need to be touching down when it is gone or you are toast.
This applies to me as much as anyone else..

Randy Snarr
N694RS

--- On Fri, 1/22/10, Terrence O'Neill <troneill@charter.net> wrote:

From: Terrence O'Neill <troneill@charter.net>
Subject: [LML] Re: Airspeed sensing switch needed
To: lml@lancaironline.net
Date: Friday, January 22, 2010, 3:08 PM

Thanks for the info, Randy.

I have my airspeed sensing switch set a 90 knots, in the gear-up circuit, so that no matter where the gear switch is, it can't raise the gear unless the airspeed is greater than 90 knots.

Same on landing. I fi forget to put the gear switch to down, the gear will come down anyway at 90 knots.

The only downside (no pun intended) is that should I want to make a gear-su forced landing, I couldn't... and have considered adding a bypass into the circuit.

Any thoughts on that/

Terrence

L235/320 N211AL