Motor " Top "

[Invité Olivier BO]

Bonjour à tous

 

Je recherche une adresse mail ou un site sur le net concernant les moteurs TOP que l'on rajoute sur presque tout les planeurs monos.

 

Merci

[Fred]

Salut,

 

Il y a effectivement des top sur des ASW24, Ls6, Ls7, ASW20, Ventus, Discus ....... pour en avoir vu en oeuvre : faut pas mal de piste !

 

Tu auras plein d'infos en regardant sous :

http://groups.google.fr/groups?hl=fr&lr=&i...viation.soaring

 

 

 

TOP Self Launch engine

This is not a translation of the online German document but based on

my experience and knowledge as an owner and operator for over 10

years. I have also met and talked with the designer.

 

Background

The Fischer TOP was designed and manufactured by Thomas Fischer in

Germany in the 1980's.

The first unit was fitted to a Kestrel 17 after a shape representing

the TOP had been fitted so that performance testing could be done to determine

the effect on glide performance. It was determined that the TOP caused 2

kilograms of drag at 100KIAS. Given that a 400 Kg glider has a glide

angle at 100 knots of about 25 or 16 Kg of drag the effect on performance can

easily be determined.

 

Technical

The unit has a 24 HP Konig 3 cylinder radial engine which develops

maximum power at 4200 rpm with toothed belt reduction giving propellor rpm of

about 2400. The fuel tanks are part of the unit and hold 8.5 liters of fuel,

good for about 45 minutes at full power. Pilot reports are that an LS4

fitted with TOP will climb from sea level to 14000 feet on a full tank.

 

There is a 3 bladed carbon and kevlar folding propellor which

automatically folds when the engine is stopped. This makes the TOP one of the

easiest to operate motor glider power units as the prop does not have to stopped

in a particular position.

There is also a safety benefit in that if the engine fails the prop

will stop and fold reducing the drag dramatically and giving a glide angle of

about 25 at around 50 knots. This makes the emergency landing much easier.

 

Extension and retraction is electric and electric start is fitted.

Several timers are built in to the control unit for ignition delay of about 3

seconds after cranking starts to give the prop time to partially open and a 12

to 15 second delay for retraction to give the engine time to cool. The

aircooled engine is very smooth with little vibration and not too much noise and

it warms up and cools rapidly. Engine starts can be done with only 50

feet altitude loss. No generator is fitted.

Batteries for the TOP are fitted in the nose of the glider which

generally means little ballast is required to bring the Center of gravity of a

TOP fitted glider to the right place.

 

Structural modifications are minimal. A couple of small bulkheads in

the turtledeck with M10 bolts built in. A hatch is required for the quick

disconnects for the throttle, choke and fuel shutoff and the multipole

electrical connector. Fitting and removing the unit takes a matter of

minutes and no adjustments are required. A starter solenoid, control

panel and engine instrument(tacho and CHT) and associated wiring are all

that remains in the glider when the unit is removed at small weight

penalty.

(a few pounds) In Germany the TOP was certified on ASW 20 and 20B, Std

Cirrus and Astir single seater. In Australia the units have been

fitted to several LS3 and LS4, a Ventus A, a Ventus C, a Discus A a LS3-17

as well as ASW20B and ASW20.

 

While you would not want to compete in an unhandicapped contest with

the TOP(you can't really carry water ballast anyway) the glider retains

its handling qualities and suffers only a small performance penalty in

cross country speed against the same glider without TOP - around 4 to 5%. It

turns many older and not so old gliders into self launchers which can be

used for fun and contest practice. The TOP can easily be removed for serious

contest work with essentially zero penalty apart from a few pounds empty

weight increase. Land out on an airfield and your crew can forget the trailer

and bring the TOP out in the back of the car!

 

The unit weighs about 46 kilograms with batteries and fuel. This

weight actually has the same effect as water ballast so the performance

penalty against the same glider without TOP is less than you might think at

higher speeds. In low speed flight the extra weight seems to be the only

noticeable difference and the turtle deck area near the trailing edge of the wing

is a bad area anyway so filling it with the TOP doesn't seem to have

bad effects at low speeds.

 

If you want to fit a TOP to other gliders than the types mentioned

there are several things to look for. You want a maximum weight of around 400 to

430 kg including the TOP and pilot, You need a turtle deck area that can have

the structural reinforcement fitted and the maximum weight of non lifting

parts should accomodate the proposed pilot plus TOP. This latter can be a

problem but it is sometimes possible to reduce placarded speeds. The old Open

Cirrus appears to be a suitable glider. The Speed Astir is another.

Some gliders were made in turbo and self launch versions with

stronger spars like the Discus and Ventus 1. Once the turbos or factory self launch

versions were in production all the subsequent gliders got the stronger spars

so that production mix ups could not occur.

My Ventus C ("a" fuselage) is one of these as was a friend's Discus

A. These gliders carry the TOP without any structural implications for the

wing.

Check with the manufacturer. Some are more helpful than others.

Klaus Holighaus was very helpful with my Ventus installation by

providing a written statement that my glider had the CM motorglider

wings and also provided the turtledeck layup details so we could

calculate the attachment strength we had. He also provided CM manuals

and a staeement that we could use those speeds and weights.

 

Around 100 TOP units were made up to end of production in the early

90's.

The unit is currently not in production but I believe the project is

for sale.

It is possible to buy the occasional used unit(sometimes with the

autobahn induced glider wreck) at quite attractive prices.

 

Limitations

A TOP fitted glider ain't a rocket ship! It will climb at around 300

feet/min and take off in less than 500 meters run to 50 feet at sea level

standard day conditions on a sealed runway. Rough soft surfaces and/or long grass

are a no no. Live at 5000 feet or more above sea level and you had better

have a long runway.

 

My wife says that the Ventus C at 2100 feet above sea level lifts off

and climbs out at similar angles to the local Piper Tomahawks and Cessnas

although the speed is about 50 knots instead of 70 to 80 knots.

 

In the event of a low altitude engine failure the prop folds and stops

and you have about Blanik performance. Ths is much better than the

13:1 to 17:1 glide angle of some of the other self launchers and even though

they would be higher in the same place the options are no better.

 

There is obviously a glide performace penalty but you still have a

high performance sailplane and if you dial in 10 % bugs and about 15%

extra weight over normal empty glider your final glide

will work out.

 

Conclusion

This device needs to go back into production! A mark 2 version with a

little more power(say 28 -32HP) would be welcome.

The current engine is in production in Canada for powered parachutes.

 

A version of the ASW24 was made with a TOP sunk into the turtle deck

with only the upper cylinder fairing and prop showing when retracted. This

caused loss of only about 1.5 points of glide versus about 3 to 4 points with

the completely external version.

The Mistral sailplane also was available with the "Kiwi" TOP version

similar to the ASW24 TOP.

Similar arrangements could be engineered to use other engines.

 

 

Certification would be a problem and was one of the reasons for the

project's demise.

Countries with sensible regulations for sporting gliders, USA(and

countries with similar Experimental regs, like South Africa) should

be good markets.

 

Anyone with further questions please email me and I'll put all the

replies togther in an amended version of this document in about a

week.

 

Mike Borgelt 28 June 2003