I just discovered that my Citation V has the STOL feature installed.

[youtube]https://youtu.be/FJP761KdTfs[/youtube]

KLUM, elevation 895, runway 36, wind 360 at 11 knots, temp 11 C, weight 11,000 lbs, Vref 90, book runway required 2480 ft (no wind number).

I got the speedbrakes out and deployed the TRs, but never got time to actually use reverse power thrust because speed dropped so fast (you have to wait for the TRs to be fully deployed). Braking was "moderate", not nearly max effort. The turn off is slightly less than halfway down the runway. I suspect a truly max effort would have stopped the plane in 800 ft.

This plane is about as capable as my MU2 was at short fields. The MU2 could land shorter, but I think the V can takeoff in less runway for any given mission profile (cabin load and leg length).

And this was after cruising at 420 KTAS, M 0.73, at FL400. The V is awesome at both being fast and being slow.

Mike C.

Is there a float STC? Bush tires?

"Can your plane land in the water?"

"Yes, once."


There is a "gravel kit" which consists of nosewheel spin up system and structurally enhanced flaps.

There was a V that operated year round in Alaska doing radar site maintenance in very remote places. Gravel kit, wide door mod, etc, operating on all sorts of unpaved surfaces including ice and snow. So it has been used as a "bush" plane in the past.

Note the mechanism on the nose gear. Spinning up the nose wheel prior to landing reduces the chance of gravel being kicked into the engines. The mechanism operated on bleed air.

Mike C.

I think there has been at least one Citation that splashed and flew again.

Bush tires would be fun but retractable landing gear apparently has no exemption in the MEL.

Doesn't the gravel kit require a crew of two (and SPE isn't adequate)?

Probably a few. Not ideal.


Not that I am aware of.

I wouldn't want the kit, adds maintenance and makes nosewheel servicing annoying.

I feel like an electric spin up kit would have been simpler, though Cessna sometimes makes bad choices when it comes to electric motors.

Mike C.

Great video Mike. What kind of takeoff performance would expect under the same conditions?

How does your fuel burn compare to your MU2 for a given trip?

Depends on winds and leg length and weather.

1300 nm into 100 knot wind (which I did recently in the V, a trip the MU2 can't do non stop), the MU2 will burn about the same fuel due to lower speed and having to stop. Flying higher and going 420 knots really cuts down the impact of headwinds.

The MU2 will have to deviate around weather, particularly in the summer, which can add distance.

On a still air day, the V uses about 70% more fuel per mile, but the true net is less than that due to the other factors.

The V will carry 9 people comfortably, the MU2 6, so the fuel per seat mile ratio is near parity, but I'll rarely have that many on board, so it is a bit of a fantasy spec.

I should also say that I am so far flying the V at MCT (max cruise thrust) and not LRC (long rang cruise). So I have not yet looked at how to be more efficient. My MU2 I flew it efficiently (FL280, 96% RPM). If I flew it fast (FL200, 100%), fuel usage would go up noticeably.

Mike C.

Same conditions, about 2400 ft per the book, but the book has been tampered with. See if you can tell from this graph:

The laws of physics don't change at 13,000 lbs.

Oddly enough, the book distance at some lighter weights is slightly longer than heavier weights. Clearly, that's tampering since adding weight never shortens takeoff.

The numbers are with an engine failure at V1 on the runway.

If I measured the ground run with both engines operating, I'd estimate about 1200 ft ground roll at 11,000 lbs. Taking off that light would be kind of weird since you are basically down to reserve fuel.

Due to fuel price here, I topped off. My takeoff weight will be abut 15,500 lbs. The book says 3100 ft. I suspect that would be 2000 ft ground run.

The V is an amazing short field airplane.

Mike C.

At my previous job in Africa they had a 560 with a gravel kit! From what I remember the wheel spin-up was working by ram air! They released the clutch around 180kts and they got a green light when the wheel reached its desired speed! I think it also had a brake in cas of go-around!

Cheers,

Felix

Impressive!

Same conditions, about 2400 ft per the book, but the book has been tampered with. See if you can tell from this graph:

The laws of physics don't change at 13,000 lbs.

Oddly enough, the book distance at some lighter weights is slightly longer than heavier weights. Clearly, that's tampering since adding weight never shortens takeoff.
...
Mike C.

Consider this case:

0 MSL, ISA (15 C), flaps 15.

11,000 lbs: 2420 ft, V1 90, Vr 90, V2 99
12,000 lbs: 2420 ft, V1 90, Vr 90, V2 99

The takeoff thrust is the same, the distance is the same, the weight is 1000 lbs less. Huh?

Any first year physics student can tell you that F = ma, and if you have the same F (thrust), but less m (weight), then a has to be larger and the aircraft will reach V1, Vr, and V2 sooner with less distance. Yet, the book shows the same numbers. You can't add 1000 lbs and not affect the acceleration.

So it is clear the numbers have been tampered with to establish bounds that are not related to true aircraft performance or to any certification requirements, either.

And yes, I do have access to a number of folks extremely familiar with aircraft design and certification who confirm this is happening.

Mike C.

Not exactly correct but close.

The gear does have a ram air feature as seen in this one on a Bravo:

But there is no brake or clutch. As soon as the gear is lowered, the ram air starts helping turn the wheel.

But there is also a bleed air feed, that's the silver hose you see. This provides bleed air to get the wheel up to speed if ram air is insufficient.

There is also a speed sensor and lights on the panel to indicate minimum and maximum RPM has been reached. That's the black wire you see in the picture.

More on its operation in this document, especially section 3.2:

https://support.cessna.com/custsupt/con ... s_id=35450

Mike C.

Depends on winds and leg length and weather.

1300 nm into 100 knot wind (which I did recently in the V, a trip the MU2 can't do non stop), the MU2 will burn about the same fuel due to lower speed and having to stop. Flying higher and going 420 knots really cuts down the impact of headwinds.

The MU2 will have to deviate around weather, particularly in the summer, which can add distance.

On a still air day, the V uses about 70% more fuel per mile, but the true net is less than that due to the other factors.

The V will carry 9 people comfortably, the MU2 6, so the fuel per seat mile ratio is near parity, but I'll rarely have that many on board, so it is a bit of a fantasy spec.

I should also say that I am so far flying the V at MCT (max continuous throttle) and not LRC (long rang cruise). So I have not yet looked at how to be more efficient. My MU2 I flew it efficiently (FL280, 96% RPM). If I flew it fast (FL200, 100%), fuel usage would go up noticeably.

Mike C.