DG-1001 Landing Gear

It is my belief to keep our customers always completely and correctly

informed even when some of the information is not always pleasant.

The large landing gear of the DG-1001 (the one without nose wheel) is certainly one of its outstanding features. It has a suspension which no other presently on the market two seater has. The tail does not make contact with the ground during a winch tow and onaero tow the plane lifts off the ground early and by itself. All these are excellent features but at the same time there is also some criticism about the landing gear.

In order to achieve a positive over center lock of the landing gear it not only has to be adjusted correctly but the gear handle has to be located tight against the cockpit wall and in front of the fiberglass angle. This should in general not present any problems but still errors were made in this respect with the result that the gear collapsed on landing. Fortunately, it is not too great a problem on grass runways, but on asphalt it is a different matter and extensive repairs are required.

A second concern was that the operation of the relatively heavy gear required a fair amount of strength in particular when the left arm because of the seating position was unable to develop sufficient power do to so. Although I myself never encountered such problem, it could easily be the case with a young girl seated in the front seat.

In addition, the gear handle is rather small in order to position it on the left side of the cockpit. But we did not want to place it on the right side as we preferred to provide a large storage pocket there.

But the customer is always king and when such comments are received we haveto act.

I can now present two improvements which are coming to resolve these problems.

1. The Compulsory Gear Lock:

Starting with work number 10-123 the compulsory gear lock will be installedon all DG-1000. This will hold the gear in positive over center lock position, gear retracted or gear down, even if the gear handle is not directly against the cockpit wall. When retracting the gear, the lock will open first only then can one move the gear.

The required forces should also be reduced due to the requirement of the rubber bumper needing to be less compressed.This improvement will also be available as a technical bulletin for optional installation on existing DG-1000.

We highly recommend this, in particular where the plane is used in Club operation.

Having said above I must add that a further improvement is available now.

2. The electrically operated landing gear for the DG-1001:

Our engineer Holger Koenen has developed an electrically operated landing gear (based on Wolfgang Dallach ideas). We have installed this electrically operated gear in our DG-1000 Demonstrator, which is now going through extensive testing.

We expect to have it ready for general installation by the end of 2008. If you want to have it installed in your ship, do not install the compulsory gear lock discussed above. Holger Koenen, member of our DG team, has put together a presentation of the design (in German), which describes the technical details of this electric landing gear.

Intentions:

Install the electric gear in all DG-1001
No extra cost for the customer
Retrofit possible for existing DG-1000's
The mechanical landing gear may still be ordered

All customers of new DG-1001's for delivery during winter 2008 will get the mechanical landing gear. All customers with later delivery dates will be notified as soon as we know the exact date for availability of the new electric landing gear. They can then opt for the electric or the manual landing gear.

- friedel weber -

Translation: Frank Pennauer, CDN

A videoclip of how the landing gear operates

It gives a good impression of how it will work (Movie with 9 MB on Size).

The Details of the New Electrical Undercarriage.

Background:

Requirements for the Electrically Retractable Landing Gear

The electrically operated landing gear for DG-1000 replaces the standard manually operated landing gear (the one without the nose wheel!) and can be installed in all DG-1000's.

We use a standard 12 Volt industrial electrical motor and we recommend the usage of two batteries for this application. Our records indicate almost all DG-1000s gliders have been ordered with two batteries. We strongly recommend 2 batteries for the Turbo version to prevent the installed computer to shut down and power itself back up again when the motor is started. Even on the pure glider a second battery makes real sense. A single battery is not always sufficient (even the solar panel has its limitations) to power the many modern electronic devices installed. (FLARM (collision avoidance device), transponder, two onboard computers and two PDAs).

The two batteries are switched together with a relay and can be charged by an outside source and/or the solar panel.

Power Consumption

The power consumption of the landing gear is so low it can almost be neglected. We tested the energy consumption by cycling the gear 400 times. The battery was far from empty. The electric power used for an afternoon of flight training (30 starts and landings) is substantially less than that used on a normal cross country flight. In such a flight all the instruments mentioned above are being used but the landing gear is typically only cycled once.

Operation

The aircraft has two complete operational installations, one in the front and the second set up in the rear instrument console. Additionally both the front and the rear have an emergency deployment mechanism.

In order to lower the gear press the toggle switch down. The red LED lights up during this process. The lower green LED is illuminated as pictured when the landing gear is down and locked. When flying the green LED turns itself off after 5 minutes.

Our main challenge when developing the electric gear was how to prevent unintended retraction of the gear when on the ground. Too many airplanes have been damaged when the landing gear collapsed or retracted when the ship hit a bump in the starting phase of an aero tow.

A device that locks the gear with the assistance of static pressure (which can be operated only at speeds above 60km/h) will not satisfy the demands. How do you retract the undercarriage in the trailer?

All the above led us to deliberately use a somewhat complicated procedure for this manual emergency operation:

Move the toggle switch up with one finger and with a second finger press the adjacent black button twice. A beep will sound twice and on the second beep the landing gear will retract. The video clip shows how it works.

This procedure is designed to ensure that no one accidently causes damage to the plane or landing gear. Every pilot must be trained on how this feature works before flying of the DG-1001 equipped with the electrically operated landing gear. This is to minimize the risk that the pilot confuse the operation of the landing gear with that of the fuel valve. This risk is more prevalent on the motor glider variant.

Emergency Deployment

An emergency operation procedure is of course also necessary for the case there is a malfunction of the power system of the landing gear. This is a manually operated fast deployment mechanism giving additional security when the electrical landing gear does not work as intended.

Watch the video to see how quickly the gear extends in this mode.

There is a very elegant solution for retracting the locked down gear in case of an emergency. It is as easy on the ground as in the air.

First use the electric switches to lower the gear. At the same time keep the red knob pulled out. This will work even when a total voltage loss should occur. If someone accidentally deploys the emergency gear extension it can be retracted without problems. This is not the case with most emergency extension mechanisms.

On the ground it is in principle completely possible to extend the undercarriage by the manual fast deployment method, and then to revert to the normal mode again. Why anybody would like to do so, is another question.

Limitations:

This new landing gear does not add any new limitations.
As before the gear can be operated at speeds up to 185 kph, both in normal mode as well as in the emergency mode.

Restrictions:

There are not any restrictions caused by the landing gear. It can be operated up to 185 km/h as well normally as with the emergency extension mechanisms.

Safety

The two separate methods to extend or retract the landing gear mean increased safety levels. In addition “the over the centre lock” is always in operation. The propulsion always pushes against it with some force, and so safely prevents unintended retraction.

Additional Costs

None!
Only the second battery and gear warning have to be added. But this is in most cases done anyway.

Disadvantages

We can envisage none.

Final Verdict

We think this new electrically operated landing gear is great. It really improves comfort and allows even the physically weakest pilots to operate it with ease even when flying solo.

We do not see any disadvantages. But since we don’t want to push our ideas on you, we will still offer the manually operated landing gear as an option.
I hope that you, our customers, will be as enthusiastic about this development as we are.

Technial Note 1000-14

This document contains the upgrades for the manuals and allows a retrofit of the electrical landing gear.

However this retrofit can be done in Bruchsal only, because it is a rather difficult job.

The first independent report:

Dear Friedel Weber,

The season is now over for a while, but your report on the electric retractable gear for the DG1000, reminds me to give you my opinion about it.

Glider pilots are rather a conservative lot and are not always positively impressed by electric"frippery". But based on my experience this innovation is part of the safety culture (NOAH, Piggott-Hook etc.) of DG Flugzeugbau.

As an instructor with many years experience I am aware of the problems which can occur when the gear is retracted during aero-tow. "Heave-Ho" and best several times, because its soo heavy to get the gear in, - and where is the horizon? and even worse where is the tow plane?

Especially with heavy Twins, weak tow planes and its high minute costs there is a tendency to retract the gear as early as possible.

How much simpler and safer in the DG-1000 with the touch of the switch, the gear retracts – no distraction just fly on.

Nice to have, but this was actually already perfect in the Original. And should the battery be empty there is always the emergency unlocking device.

More safety, great !!!, what more to you want without additional cost?
The electric gear for single seaters!! Smiley

Best Greetings
Yours

Claus Triebel

Retrofitting an electrically driven undercarriage

Since the beginning of 2009 we have been able to offer retrofitting an electric undercarriage to existing gliders. The cost for this, incl. labour, is EUR 5,800 +VAT.

Unfortunately there is rather a lot of work to do when a glider already has a mechanical undercarriage fitted, however we would strongly recommend this retrofit to you as the electric undercarriage represents a massive improvement to the glider.

We have a lot of extremely positive feedback from the buyers of the last 12 gliders which had the electric undercarriage fitted as standard, and we have not had a single glitch with it!

All new glider will have the electric undercarriage fitted as standard,

without additional cost.