Help! Need a Bit of Technical Input - DC-3 Landing Gear vs. A380

[V2-OMG!]

Hi - our photography/research class was given an assignment. We are supposed to take a photo of something old and something new, then write a paragraph about each.

My photos are landing gear - a DC-3 and A380.

There are so many knowledgeable people here. Could I please have some input as to how the DC-3 landing gear compares to the A380?
It does not have to be technically exhaustive, but any input re: design features and operational specs like back-up deployment etc. would enhance this project.

Thank-you.

[Old Fella]

Wind-up ???

As the saying goes "A picture is worth a thousand words". The comparison should be obvious, especially to an aviation geek and aviation magazine editor !!!

[V2-OMG!]

Wind-up? Who has time for a wind-up?

I am just trying to make a decent request for help.

[etudiant]

There is a plethora of stuff available online on both topics.
A Bing search provides photos, texts and links to multiple sites and technical details, way more than is needed to write a paragraph.
So what is the help that you are requesting? Is it personal anecdotes or details of operating experience with these products?

[John Farley]

The DC3 undercarriage design was typical of a 1930s design and relatively simple. The A380 being very heavy could potentially damage runway surfaces unless its weight was distributed over the runway surface. Hence multiple wheels were needed.

[Metro man]

IIRC The DC3 undercarriage was held up by hydraulic pressure and would extend in the event of a loss.

[MarkerInbound]

The hydraulic system in a DC-3 is a simple 900-1000psi system. There is a system pressure gauge and a "gear down line" pressure gauge. The landing gear lever is simply a ~18 inch extension from the landing gear selector valve and is located below and behind the First Officer's left arm rest. There is no modern symbolic tire at the end of the gear level as is found on modern airplanes. As stated above the gear is held up solely by trapped hydraulic pressure. On some aircraft it could become necessary to re-retracted the landing gear if gear down pressure started building over time. In the event of a loss of hydraulics the landing gear will free fall when the trapped pressure is released.


The gear is held down in the down position by trapped hydraulic pressure and a mechanical safety latch which holds the gear linkage to the aft end of the wheel well when the gear is extended and the safety latch is engaged. The safety latch is controlled by a short lever on the floor just inboard of the Captain's seat. So retracting and extending the landing gear is a multi-step process. To retract the gear you first rotate a clip at the end of the safety latch lever 90 degrees forward so it is no longer holding the safety latch lever to the floor. You then raise the safety latch lever to a 45 degree position from the floor. The safety latch lever also controls a dog and shoe on the landing gear selector valve so now you can raise the landing gear lever to retract the landing gear. When climb power is set you move the landing gear lever to the "OFF" position. When the landing gear lever is moved to OFF the safety latch lever drops to a ~20 degree position off the floor.


Extending the gear is the reverse. Move the landing gear lever to the down position. When the gear down line pressure and the system pressure gauges match and you have a green light return the gear lever to the OFF position. You can look out the window to confirm that landing gear is down. You then push the gear safety latch lever down flush with the floor and flip the clip up over the end to hold it down.


There is a lever on the bottom of the throttle quadrant that when moved aft raises a yoke or collar off a pin on the shaft that the tailwheel rotates around and allows the tailwheel to swivel freely. In the forward position the yoke will drop and catch the pin when the tailwheel is straight and lock it in position.


I know nothing about Airbus landing gear systems.

[Vinnie Boombatz]

Airbus A380 Specs - Modern Airliners

"The 22-wheel Goodrich landing gear consists of two under-wing struts each with four wheels, two central under-fuselage struts each with six wheels and a twin nose wheel. Each landing gear supports about 167 tonnes. Messier-Dowty supplies the nose landing gear with 350bar hydraulic pressure and Messier-Bugatti the braking and steering systems. Smiths Aerospace supplies the landing gear extension and retraction system. The load on the airport runways and aprons are of similar magnitude to that of a 747. "

"Maximum Take-off Weight 560,000 kg (1,234,600 lb)
Maximum Landing Weight 386,000 kg (850,984 lb)"

http://www.sandv.com/downloads/0811obse.pdf

"The six-wheel landing gear system weighs approximately 12,000 pounds, and its size exceeds 25 feet when fully extended."

http://faculty.dwc.edu/sadraey/Chapt...r%20Design.pdf

"In general, the landing gear weight is about 3% to 5% of the aircraft take-off weight."


https://en.wikipedia.org/wiki/Airbus_A380

https://en.wikipedia.org/wiki/File:A...0_Fahrwerk.jpg

Ref 216 in the Wikipedia article is now here:

https://www.flightglobal.com/news/ar...s-a380-209189/

A380 data from Airbus:

http://www.airbus.com/fileadmin/medi...80-Dec2014.pdf

Airbus A380-800F Wide-Bodied Freighter - Aerospace Technology

"Goodrich has been contracted to supply the two six-wheel under-fuselage landing gear and the two four-wheeled wing-mounted landing gear. The wing-mounted landing gear is slightly forward of the fuselage-mounted gear. The wheels on the main landing gear are fitted with carbon brakes.

The twin wheel nose landing gear is supplied by Messier-Dowty. The steering control is via the nose gear and via the rear axle of the fuselage landing gear. The gear allows u-turn manoeuvres on a 60m-wide runway."

Machinery Features Articledetailaspxarticleid=3903 | Machinery

"Messier-Dowty, Bidos, France has delivered the first test A380 nose landing gear to Airbus UK, Filton. At 4.8 m tall when fully extended, it is the largest landing gear ever supplied by Messier-Dowty to Airbus "

DC-1 DC-2 DC-3 C-47 Dakota Aircraft

"Max. gross weight: From 25,000 lbs (11,340 kg) to 36,800 lbs (16,692 kg)

Height: DST & Std. 16 ft, I I in (5.16 m)"

The A380 nose gear is slightly shorter (36 cm) than the max height of the whole DC-3.

The total landing gear weight for the A380 is probably greater than the max gross weight of the whole DC-3. Note that the 12,000 lbs quoted above is for a single 6-wheel body element of the full landing gear.

The max gross weight of the A380 is about 33.5 times that of the DC-3.

The DC-3 Hangar on douglasdc3.com DC3 C47 C-47

DC3specs - The Business of Funding and Flying a Plane

"Height 16ft 11½in "

tech

dc3tec

http://www.eliteflightservices.com/p...GearBrakes.pdf

[Greek God]

IIRC the DC3 gear didnt fully retract so in the event of a gear up landing the tyres would still rotate.

[pattern_is_full]

....and probably more importantly, would prevent the aircraft weight from settling on, and damaging, the nacelles. Pick it up, dust it off, and start all over again.

What's probably most newsworthy about the comparative technology is how little it changed, in the gross details, over 70 years. Hydraulic folding things, with angled stabilizing struts, and changes in orientation to accomodate fitting into different parts of the aircraft. The one major conceptual change is that the A380 main gear can steer a bit, to accomodate the long wheelbase.

[stilton]

Still find it odd that AB elected for a bogie design that trails forward.


This is a very unforgiving configuration on landing.

[V2-OMG!]

Thanks to those who didn't think this was a "wind-up."

The fact is - I do edit a small vintage aviation rag - but know little about aviation. They gave me the position (I am not paid for it) because I have an ability to compile information, then deliver it in a way that is enjoyable (hopefully) to the professional and layperson alike.

I have a question: were the DC-3 tires filled with air or nitrogen?

[V2-OMG!]

So what is the help that you are requesting? Is it personal anecdotes or details of operating experience with these products?

etudiant, some anecdotes or operational details would certainly add interest. If you have any, please share!

[Metro man]

The DC3 needed to be landed on the main wheels first, three point landings could be done but could easily break its back.

The tailwheel could be locked to assist in directional control.

[Capt Claret]

How bloody sad that a question can't be asked and answered without the smart arse assumptions.

I commend you OMG for keeping your cool and not biting back.

[Avtrician]

As I recall, the DC3 tyres were filled with air. They wernt heavily stressed on take offs and landings so no high temperatures to worry about. Also, when they were designed, I dont think nitrogen was so easy to come by, but there was lots of air..

[MarkerInbound]

....and probably more importantly, would prevent the aircraft weight from settling on, and damaging, the nacelles. Pick it up, dust it off, and start all over again.

The props would be folded back and if that happened under power it's an engine change. I remember a conversation with an old mechanic who said from maintenance's perspective it would be best to land gear up with the props windmilling. Then two tips would be folded back and they would have to run out the crankshaft but if it passed the test the engine would be considered good. If the prop was feathered the landing force could be transmitted along the cord of the prop and rip the engine off the firewall.

[Sailvi767]

It was my understanding that they always used 80% nitrogen when filling DC3 tires.

[peekay4]

Filling tires with > 95% nitrogen is only required for aircraft with a maximum takeoff weight of over 75,000 lbs. (Per 14 CFR 25.733).

That's because heat from the extreme braking energy on heavier aircraft could cause the tire to release volatile gasses. These gasses could cause the tire to violently explode when combined with oxygen inside the tire at high temperatures.

So on heavier aircraft it is important to remove the oxygen from the tires, replacing it with an inert gas (such as nitrogen).

DC-3 with MTOW of around 26,000 lbs: regular air ok (78% nitrogen, 21% oxygen).

A380 with MTOW of about 1,200,000 lbs: dry nitrogen or other inert gasses (must be < 5% oxygen)

[Derfred]

Still find it odd that AB elected for a bogie design that trails forward.

This is a very unforgiving configuration on landing.

That is a myth.