BeechTalk - BT

Username Protected · **Posted:** 09 Jan 2014, 11:24

Pretty sure the Cirrus jet has a retractable landing gear... and a V-tail. That should tell you all you need to know.

Username Protected · **Posted:** 09 Jan 2014, 11:54

Username Protected wrote:

Pretty sure the Cirrus jet has a retractable landing gear... and a V-tail. That should tell you all you need to know.

Totally agree. That's the bottom line.

I think the Cirrus would be 20knots+ faster if it were a retract.

Get your hands on one of those wheel fairings. Drive down the freeway at 70mph and hold it out the window and see if it doesn't try to rip your arm off.

That said, I think Cirrus made the right decision with the fixed gear but it was done for cost reasons.

Username Protected · **Posted:** 09 Jan 2014, 12:02

Username Protected wrote:

Pretty sure the Cirrus jet has a retractable landing gear... and a V-tail. That should tell you all you need to know.

Totally agree. That's the bottom line.

I think the Cirrus would be 20knots+ faster if it were a retract.

Get your hands on one of those wheel fairings. Drive down the freeway at 70mph and hold it out the window and see if it doesn't try to rip your arm off.

That said, I think Cirrus made the right decision with the fixed gear but it was done for cost reasons.

Username Protected · **Posted:** 09 Jan 2014, 12:03

It doesn't tell me all I need to know.

It's comparing apples to oranges. A gear extended at 180 kts is not quite the drag as one at 450 kts.

I don't know what the weight of a retractable gear apparatus is compared to a fixed gear, but it is probably appreciable. I did read the engineering data sometime ago on the Cirrus and the penalty for the fixed gear was only 5 kts according to wind tunnel tests factoring in the weight penalties etc.

Username Protected wrote:

Pretty sure the Cirrus jet has a retractable landing gear... and a V-tail. That should tell you all you need to know.

Username Protected · **Posted:** 09 Jan 2014, 12:13

Username Protected wrote:

I did read the engineering data sometime ago on the Cirrus and the penalty for the fixed gear was only 5 kts according to wind tunnel tests factoring in the weight penalties etc.

If I were a marketing guy for Cirrus, I would say the same thing.

The marketing guys aren't going to advertise "boy, if we weren't looking to cut cost, this thing would be a lot faster".

Username Protected · **Posted:** 09 Jan 2014, 12:19

Username Protected wrote:

Pretty sure the Cirrus jet has a retractable landing gear... and a V-tail. That should tell you all you need to know.

Totally agree. That's the bottom line.

I think the Cirrus would be 20knots+ faster if it were a retract.

Get your hands on one of those wheel fairings. Drive down the freeway at 70mph and hold it out the window and see if it doesn't try to rip your arm off.

That said, I think Cirrus made the right decision with the fixed gear but it was done for cost reasons.

Username Protected · **Posted:** 09 Jan 2014, 12:22

I knew that was coming.

First time for everything.

Honestly though, it's not the first time. Matt agreed with me on something else a while back. We both wear ass-less chaps when home alone.

Username Protected · **Posted:** 09 Jan 2014, 12:31

Username Protected wrote:

I knew that was coming.

First time for everything.

Honestly though, it's not the first time. Matt agreed with me on something else a while back. We both wear ass-less chaps when home alone.

Jason, I think that something we can ALL agree on! :cheers:

Username Protected · **Posted:** 09 Jan 2014, 12:51

I don't think Cirrus can fit the gear into the wings without sacrificing something else like Fuel capacity. They would have to likely use a design like Cessna uses on the singles.

Username Protected · **Posted:** 09 Jan 2014, 12:51

Curiously lancair came to the same conclusion about gear. So did cessna with the NGP project. Whatever the reason it must be compelling to have three separate teams reach the same solution to a problem that had previously uniformly been solved with RG.

Username Protected · **Posted:** 09 Jan 2014, 12:59

Username Protected wrote:

I knew that was coming.

First time for everything.

Honestly though, it's not the first time. Matt agreed with me on something else a while back. We both wear ass-less chaps when home alone.

Attachment:

eyebleach1.png

Username Protected · **Posted:** 09 Jan 2014, 13:14

In terms of the aerodynamics, a few things to consider:
1. Drag is largely based on KIAS, not KTAS.
2. Look at where the fixed gear joins the fuselage on all three examples, Lancair, Cirrus and Cessna.
3. Retract adds a lot of weight, complexity, and size to the plane. Increasing the size of the wings, fuselage, or the join between the two increases drag.

So ya, the impact at the slower speeds these planes fly it really is not that big a hit in terms of speed and a very significant cost, complexity and other factors savings.

Tim

Username Protected · **Posted:** 09 Jan 2014, 13:26

Tim, you are generally correct when dealing with low speeds. However as you operate in the transonic range of subsonic jets there are other drag factors that must be considered with large wheel fairings that does depend on TAS or Mach number. A minor point for discussion but certainly quite relevant if discussing a fixed gear jet.

Username Protected wrote:

In terms of the aerodynamics, a few things to consider:
1. Drag is largely based on KIAS, not KTAS.
2. Look at where the fixed gear joins the fuselage on all three examples, Lancair, Cirrus and Cessna.
3. Retract adds a lot of weight, complexity, and size to the plane. Increasing the size of the wings, fuselage, or the join between the two increases drag.

So ya, the impact at the slower speeds these planes fly it really is not that big a hit in terms of speed and a very significant cost, complexity and other factors savings.

Tim

Username Protected · **Posted:** 09 Jan 2014, 13:47

Username Protected wrote:

hey, 5kts is 5kts!

So far my SR22T is as fast as my A36TN.

Username Protected · **Posted:** 09 Jan 2014, 14:24

Username Protected wrote:

Speaking of sleek, high-performance retracts that pre-date the Cirrus, does anyone remember this bird?

Bellanca Skyrocket II

General characteristics:

Crew: one pilot
Capacity: 5 passengers
Length: 27 ft 0 in (8.23 m)
Wingspan: 35 ft 0 in (10.67 m)
Height: 9 ft 0 in (2.74 m)
Wing area: 183 ft2 (17.0 m2)
Empty weight: 2,490 lb (1,129 kg)
Gross weight: 4,200 lb (1,905 kg)
Powerplant: 1 × Continental GTSIO-520F, 435 hp (325 kW)

Performance:
Maximum speed: 340 mph (547 km/h)
Range: 2,300 miles (3,700 km)
Service ceiling: 30,000 ft (9,100 m)
Rate of climb: 2,080 ft/min (10.6 m/s)

http://en.wikipedia.org/wiki/Bellanca_Skyrocket_II

My former professor at Ohio State, Gerry Gregorek did some work on this airplane and was always one of his favorites. The performance was incredible...

I've never heard of the composite SE 421. Sounds amazing, what happened to it?

Retractable Gear Cirrus