Electrically controlled surfaces of the Fw 190

[Jenisch]

Guys, some doubts:

The 190 can be considerate as an aircraft with a Fly-by-wire system?

It was pioneer, eletrically controlled surfaces were used by other aircraft in WWII?

How it provided a differential in damage control in comparison with other control surface systems?

The tactical significance of the system to maneuvers was significant?

The system had palpable disadvantages?

Thanks since now for the answers.

 

[FLYBOYJ]

Fly by wire? AFAIK the Fw 190 used pushrods on most if not all of its major flight controls

 

[Milosh]

The only surface that was controlled with electricity was the stab, which used an electric powered screw jack to change the incidence.

The ailerons used rods only while the rudder and elevator used both rods and cables.

 

[Jenisch]

The only surface that was controlled with electricity was the stab, which used an electric powered screw jack to change the incidence.

The ailerons used rods only while the rudder and elevator used both rods and cables.

Ok.

Now I confirmed, the late D models would feature eletric surfaces.

 

[iron man]

Ok.

Now I confirmed, the late D models would feature eletric surfaces.

You mean late -11's? -13's?

-9's were little more than the standard A-8 airframe, with the "Jumo" mods for the weight and balance "issues".

Got a source?

Care to share it?

Or is this another "Luft '46" thing?

 

[Jenisch]

You mean late -11's? -13's?

-9's were little more than the standard A-8 airframe, with the "Jumo" mods for the weight and balance "issues".

Got a source?

Care to share it?

Or is this another "Luft '46" thing?

Perhaps not the most reliable one, and you have so speak Spanish:
View: https://www.youtube.com/watch?v=-3kU4Ice3_Q

 

[Siegfried]

Guys, some doubts:

The 190 can be considerate as an aircraft with a Fly-by-wire system?

It was pioneer, electrically controlled surfaces were used by other aircraft in WWII?

How it provided a differential in damage control in comparison with other control surface systems?

The tactical significance of the system to maneuvers was significant?

The system had palpable disadvantages?

Thanks since now for the answers.

The electrical control was used on the all moving vertical stabaliser and I suspect also undercarriage and flaps as well. I do know latter versions switched to hydraulics over raw materials shortages. Care was taken to protect the battery via armouring.

A big advantage of electrical systems was
1 No dangerous flamable hydraulics. Getting out of a flamming lancaster filled with leaky hydraulics was not fun. US electric powered systems (tuttets) were less likely to produce this scenario.

2 Electric cables don't bleed out. A circuit breaker can be used to isolate a faulty circuit whereas a slow leak can bleed out a hydraulic system.

Unfortunatly electric system are less responsive when heavy loads are involved. Also there is a tendancies to underestimate the high quality of termination and connection required. It's more than just screwing a wire into a terminal.

Very few aircraft used power assisted controls in WW2 and they were all hydraulic:

The P-38J (also P-38LO-25 I think) had power assisted ailerons. Possibly also C-46 commando (late models)

On the German side there definetly was the Do 335 and FW 190D-13 which used hydraulic boost. The Ta 152 would have received the FW 190D-13 system in future versions.

He 162 and Ju 290 may also have had hydraulic boosted controls (the Greg Goebel site makes this claim re He 162), however authors sometimes get confused between power boosted controls and servo-tabs. The servo tab is a small surface on an aileron, rudder or elevator that is rigged to opperate in the opposit direction to the desired flight surface movement so as to push the rudder or aileron in the desiered direction. The flight surface in these is then also attached via by springs to the control surface rather than directly or simply left floating. If springs are not used they are dirtectly linked they called 'balance tabs'. The purpose of balance tabs is to reduced to aileron loads whereas the purpose of servo spring tabs is to provide the force but somewhat assisted by connection via springs. Geared servo spring tabs reduce the amount of servo tab assist at speed to prevent the pilot from overstressing the airframe from too light a load.

Many German aircraft did use servo/spring tabs such as Ar 234, Me 262, He 177. Somewhat famously some Me 109's )eg made by WNF) were issued with them but little photographic evidence remains (except a few drawings and references). The FW 190 used friese ailerons, which also reduce load somewhat. The massive B-36 did NOT have power boosted controls but provided light control forces via a well designed geared spring servo tabs. Servo tabs work well and are still in use in commuter airliners as large as the ATR 72 however they can be difficult to tune across a wide speed range and can easily lighten loads so much that the airframe can be over stressed.

Late war USN fighters(eg Hellcat) added geared spring servo tabs to increase high speed roll rate.

I'll let reader do their own research in aircraft rigging!

Electrical power controls are even now rare, the 1950s douglass skyshark tried to use them but the system was not responsive enough. Even today the
A380 and F-35 Power-by-wire flight control actuators are electrohydraulic with their own self contained electric motor reversible powered pump.

Pure electric controls via permanent magnet servo motors and electronic controls is now possible but not yet accepted in the industry.

 

[davebender]

Along that same line of thought....

Otto Carius (Tigers in the Mud) provides a good description of how accurate and responsive the Tiger Tank hydraulic turret motor was.

The turret was turned by a hydraulic gearbox. The gunners feet rested on a tilting platform. If he pressed the tip of his foot toward the front, the turret turned to the right; if he pressed with his sole to the rear, it turned to the left. The more he pressed in the corresponding direction, the faster the movement. At it slowest, a 360 degree revolution of the weapons in the turret took sixty minutes. At it quickest, it took sixty second. Extreme aiming accuracy was thus ensured. The practised gunner didn't need to adjust afterwards with his hand.

The last sentence is the critical point. WWII tank gunners had a handwheel for fine adjustment of the turret. Not having to use that handwheel was a key advantage for Tiger Tank gunners. It often allowed him to shoot first, while his T-34 opponent with electrically powered turret was still struggling to aim.

 

[stona]

To clarify Siegfried's post above re electrical flight control systems on the Fw190.
The tailplane incidence was controlled by an electric motor fitted in the base of the vertical stabiliser (fin).
The flaps were indeed electrically driven by a motor via a pushrod.
The main gear was raised by an electric motor mounted in the main wing spar via a drive unit. The drive unit is the round lump you see on the front of the spar above the radius strut(s).The tail wheel was raised via a cable attached to the starboard main gear,not exactly high tech.
This is not by any stretch of the imagination "fly by wire" technology.
Cheers
Steve

 

[cimmex]

"Stona" is absolutely correct in his statement the only thing to add is the electric driven propeller pitch controll.
Regards
cimmex

 

[Denniss]

"Stona" is absolutely correct in his statement the only thing to add is the electric driven propeller pitch controll.
Regards
cimmex

Wasn't this just an option for manual settings? AFAIR they had an automatic hydraulic system in the BMW 801 except the 801A series.

 

[cimmex]

at least in the FW190 the propeller pitch control at the BMW801 is the electric driven both in the auto and manual mode which is selectable by a switch. To control the manual mode a rocker switch is provided at the throttle lever.
Regards
Cimmex

 

[Siegfried]

Along that same line of thought....

Otto Carius (Tigers in the Mud) provides a good description of how accurate and responsive the Tiger Tank hydraulic turret motor was.

The last sentence is the critical point. WWII tank gunners had a handwheel for fine adjustment of the turret. Not having to use that handwheel was a key advantage for Tiger Tank gunners. It often allowed him to shoot first, while his T-34 opponent with electrically powered turret was still struggling to aim.

I recently came across a Bosch-Rexroth system that opperates an underwater crane to precisely lift an object of the ocean floor for opperation in heavy North Atlantic swells. Only hydraulics could be made fast and powerfull enough to compensate against the heavily pitching ship while hundred tons plus loads were positioned. Underwater the sling is a steady as if it were fixed to a building. Things we do for oil.

It's interesing what you point out about the Tigers traverse being precise, the T-34 had a very fast traverse but it seems that the fine adjustment required negated some of the advantages. Uniquely the Sherman had a power elevation, which worked electrohydraulic via a type of switch contact called a silverstat which was basically whisker wires touching a gyroscope; it wasn't really that effective though it supossedly helped get a round of quicker. There were a few Panzer III which had the whole 3.7cm or 5.0cm gun stablised via a massive 6" or 8" gyroscope directly however at the end of the war a system like the US system was to be installed in Panther and Tiger. A refinement being that the optics was stabalised seperatly and a firing circuit was to fire the gun when it was aligned with the optics (in the manner of a naval gun)

Back to aviation: US gun turrets tended to be electrically powered using a rotating amplifier called an amplidyne. You could regard it as a motor generator which amplified via adjustment of the field however the amplidyne was very time responsive compared to the simpler 'ward lenard' systems used by other nations and which were often inadquet as the were too unresponsive.

US gun turrets which used a rheostat (variable resistor) which the gunner adjusted to position (speed control) of the the turret via the amplidyne and an electric motor. The B-29's GE system also used amplidynes however the position commands came from an electromechanical computer which simply pointe the guns in the same direction as the gunsight with various ballistic parameter compenstated.

The British used hydraulics for most things. The Germans used both eg electric dorsal turrets though their remote controlled systems were either mechanical hydraulic eg Me 410 or Ju 388 or electrohydraulic (He 177 dorsal). They used a type of amplifier called a 'magnetic amplifier' based around a saturable reactor to position the hydraulic spool valve. No vacuum tubes were required. A special high bandwidth spool valve with a winding to prevent self inductance was developed for the V2 rocket motor exhaust fins. Basically the application of a DC current could be used to saturate a choke coil and make it look like an aircore and allow current to pass. They stabalised their naval optics this way as well.

The technology used to stabalise the V2 (high bandwith electohydraulics, electronic analog computers) would have made a very effective, cheap and fast power driven FLAK gun.

Back to aviation again.

In WW2 war aviation novels one often read about an aircraft (lancaster) loosing its flight controll rigging due to battle damage, however the pilot is able to use electric trim tabs to get the aircraft back home. So, there may have been a sort of fly by wire.

 

[Jenisch]

What were the advantages of eletric trim with hydraulic surfaces, just the possibility of use the trim tabs to control the plane in case the hydraulics fail?

 

[stona]

What is the advantages of eletric trim with hydraulic surfaces, just the possibility of use the trim tabs to control the plane in case the hydraulics failed?

The electric motor alters the angle of incidence of the tailplane,the horizontal stabilisers. It doesn't work on the elevators.

This method of longditudinal trimming by "tilting" the tailplane was common to many German aircraft of the period. The tailplane of a Bf109E had a range of near enough 12 degrees (+3.4 to -8.4) but no electric motor. The pilot had to crank the trim wheel,one of the two big wheels (30cm) to his left,5 and 3/4 turns to effect the full range of movement,though I can't imagine why he'd ever need to do that in normal flight conditions!

Cheers
Steve

 

[FLYBOYJ]

What is the advantages of eletric trim with hydraulic surfaces, just the possibility of use the trim tabs to control the plane in case the hydraulics failed?

The electric motor alters the angle of incidence of the tailplane,the horizontal stabilisers. It doesn't work on the elevators.

This method of longditudinal trimming by "tilting" the tailplane was common to many German aircraft of the period. The tailplane of a Bf109E had a range of near enough 12 degrees (+3.4 to -8.4) but no electric motor. The pilot had to crank the trim wheel,one of the two big wheels (30cm) to his left,5 and 3/4 turns to effect the full range of movement,though I can't imagine why he'd ever need to do that in normal flight conditions!
Cheers
Steve

When you are flying, especially a high performance aircraft, you are continually trimming the aircraft around the pitch axis. There will be the need to trim during climbs, descents (adding or reducing power), when the flaps are deployed or retracted and when the landing gear is raised or lowered. Usually a trim wheel is installed and is turned as required but you are taking one hand off the throttle to do this. Aircraft with electric trim usually has a switch on the stick or yoke and trim can be easily activated with the thumb.

 

[stona]

at least in the FW190 the propeller pitch control at the BMW801 is the electric driven both in the auto and manual mode which is selectable by a switch. To control the manual mode a rocker switch is provided at the throttle lever.
Regards
Cimmex

Yes. These controls.

The Fw190 had a good engine and propeller management system (kommandogerat) which meant that the pilot could manage everything with that one throttle lever. The management system set the propeller pitch,timing,mixture and,if I'm remembering correctly,supercharger gear (someone else may have to look that up ).
Cheers
Steve

 

[stona]

Sorry Flyboyj,I meant I couldn't see why he'd need to crank it through its entire range,all 5 and 3/4 turns,in normal flight conditions.12 degrees would be an enormous change in trim!
That trim wheel lies right next to the flap wheel and allied test pilots flying the Bf109 liked the ability to turn the two together hence simultaneously compensating for changes in trim as the flaps were lowered or raised. Still had to take their left hand of the throttle to do it though.
Cheers
Steve

 

[Siegfried]

Yes. These controls.

The Fw190 had a good engine and propeller management system (kommandogerat) which meant that the pilot could manage everything with that one throttle lever. The management system set the propeller pitch,timing,mixture and,if I'm remembering correctly,supercharger gear (someone else may have to look that up ).
Cheers
Steve

Apparently a very thorough system, for instance it also controlled propellor pitch as well as engine RPM and also controlled pitch to prevent overspeed in a dive and so was more than just a constant speed system. I believe the technology came in from BRAMO (Brandenberg Motor works) when that company (previously parth of Siemens and Halske) was purchased by BMW. It initially caused some problems when a supercharger gear automatically changed at the apex of a loop with Kurt Tank and the controlls of a FW 190 apparently almost leading to a spin. A Kommandogeraet like this was later standard on Daimler Benz and Jumo engines as well. It sounds to me as if the Berlin based Bramo had better technology than BMW.

 

[Deleted member 68059]

A long dead thread, but I do feel its worth restarting as I think some of the commentary has been a little unfairly unfavourable towards the degree of electrification used in the Fw190,
as this British Air Intelligence evaluation shows.