Multi Electric Engine Throttle Control

[chris collis]

Looking for advice or suggestions for setting up separate transmitter throttle controls to run two inboards independent from the outboards .The reason for this is that I am starting to build a 94in Sunderland to be flown off water but needs directional control when taxiing. The thought being using the inboards only with the airflow over the rudder to give it direction.Sunderland’s had no rudder. The transmitter I’m using is a Hitec Aurora 9x ,so I am thinking of using the two side sliders as throttle control.left side for inboards and right side for outboards.Don’t know if this is a viable method so any thoughts,suggestions or alternatives would be gratefully appreciated. I will also be using the model at our flying field and then stripped down for Pss.

[Paul De Tourtoulon]

I tried it on my Beaufighter ( twin Saito's ) not at all practical, but probably ok in the water on electrics to manoeuvrer.

[chris collis]

Cheers Paul,This will be my first foray into four engined flying boats so trying to forestall any water handling problems.

[Frank Skilbeck]

Chris, I don't know if your Hitec 9 will do this, but what I do on my foamy Catalina is have a bit of rudder mixed in with the engines, so I can manoeuvre on the water, I have it on a switch so I can switch the rudder mix off for normal flying. Note you don't need much rudder input to get differential throttle steering. I wouldn't use sliders for throttle management, you really need them on the throttle stick, what I would do is put the port and starboard ESCs on separate channels then have a rudder mix into them to give you differential thrust for manoeuvring.

[chris collis]

Hi Frank,So you would have the two starboard ESC’s linked together and the two port ones the same and then mix in on a switch to the rudder and just use the throttle stick for manovering on water?Then when model is lined up for takeoff,flick the switch to power up all motors to equal revs?many thanks.

[Denis Watkins]

Just be mindful, on many / most transmitters, the Failsafe does not work fully across Mixing.

Just test it as you go.

[chris collis]

Ok,thanks Denis.Will definitely have to keep that in mind and will have to do a lot of reading of the manual!

[Andy Gates]

I have done exactly as Frank has done which for me works perfectly, both on a Catalina and on a Twin Otter.

 

I would not recommend flying with the differential switched in as it makes the machine quite uncomfortable to fly in turns.

 

However switching it in for things like stall turns (I know - not a scale manoeuvrer for either aircraft) is an interesting experience, I am sure the passengers would be using their sick bags!

[chris collis]

Would you know if there is any difference in water handling between two engined Catalina and four engined Sunderland?Getting a little bit stumped as to how to achieve this relatively simply without affecting the flight envelope.Many thanks Andy 

[Andy Gates]

I would imagine that with the motors further outboard on the Sunderland than the Catalina, differential throttle would be way more effective.

 

My suggestion is to look for Ivan Pettigrew or BIMBO threads on RCGroups as Ivan does lots of electric seaplanes including a Martin Mars & Sunderland. Mike Roach has done a Princess in the BIMBO's thread.

[chris collis]

Many thanks Andy,will have a good look at the threads and see what transpires.

[Frank Skilbeck]

On 31/12/2022 at 16:55, chris collis said:

Hi Frank,So you would have the two starboard ESC’s linked together and the two port ones the same and then mix in on a switch to the rudder and just use the throttle stick for manovering on water?Then when model is lined up for takeoff,flick the switch to power up all motors to equal revs?many thanks.

Basically yes that's what I do, manoeuvre the model to the take off position, flick the switch, allow the model the weathercock into wind and then power away. My Catalina has no water rudder.

 

On my radio I could set up 4 throttle channels and just have the outer motors with the rudder mix, but it would mean having a receiver with enough spare channels.

[Andy J]

Recall on my 4 engine depron puddle build I also used a 2 position switch to couple the rudder to the throttle on two engines. Using contra rotation is also a must for a four engine build.

[eflightray]

I scratch built a Sunderland back in 2010, (still have it), some balsa framing but mostly using Depron foam.

Flown it off water and of grass, (very short sports ground grass), sliding on its belly).

No plans, just making it up as I went along.

Span - 90" Detachable outer wing panels for transport, and/or complete wing

Motors - Keda KD 2217/16 brushless, 1050kv

Props - GWS 8 x 6 x 3 blade

Lipos - 2 x 4500mAh 3s one for the inner pair, one for the outer pair

Weight - 7Lbs-2oz flying.

Uses differential throttle, Spektrum rc gear.

Ray.

 

[chris collis]

She looks amazing Ray!Thank you for all the information.Do you have flaps on her for takeoff and landing and with your battery setup what flight duration are you getting?Have you re enforced the keel for field landings?As Andy has said,I would probably attempt to use a two position switch for taxing and contra rotating props.I’m going to be using a nine channel Rx so all channels will be used.Only time will tell!

[Paul De Tourtoulon]

13 hours ago, Andy Joyce said:

Recall on my 4 engine depron puddle build I also used a 2 position switch to couple the rudder to the throttle on two engines. Using contra rotation is also a must for a four engine build.

Oh dear then my 4 engine Lancaster is doing it all wrong ! also both my twin engine planes are the same all the engines turn in the same direction,,,

[leccyflyer]

Sunderland looks superb as ever Ray. 😎

[Craig Carr]

15 hours ago, Andy Joyce said:

Recall on my 4 engine depron puddle build I also used a 2 position switch to couple the rudder to the throttle on two engines. Using contra rotation is also a must for a four engine build.

I wouldn’t particularly say it’s a must,  My A400 flew perfectly with all 4 motors rotating the same direction

[Andy J]

Just makes it a bit easier Craig getting rid of the induced torque produced by 4 engines running in the same direction. Having said that I still ended up upside down in the water on the first flight. Had to wait some time before it drifted into the bank so the motors got a good soaking. Model has not flown for some years now so assume the motors are well rusted up by now.

 

As for thrust direction got it completely wrong on a high wing design pictured below as forgot to add some upward thrust to compensate for the high motor position.

 

 

[eflightray]

7 hours ago, Paul De Tourtoulon said:

Oh dear then my 4 engine Lancaster is doing it all wrong ! also both my twin engine planes are the same all the engines turn in the same direction,,,

I only used standard and reverse pitch props on my Sunderland as I wasn't sure what difference it would make being on water.

All my largish other multi motors, twins and fours, ( Catalina - C160 Transall - B17 - Lancaster) used the standard rotation pitch props with no noticeable affect regarding trim or handling, so no need to change to counter rotating my opinion.

 Ray

Edited January 2, 2023 by eflightray
Spelling correction.

[Andy48]

7 hours ago, Paul De Tourtoulon said:

Oh dear then my 4 engine Lancaster is doing it all wrong ! also both my twin engine planes are the same all the engines turn in the same direction,,,

Real Lancasters had all their props rotating in the same direction along with many other WW2 multi engine planes like the Mosquito.

[john davidson 1]

8 minutes ago, Andy48 said:

Real Lancasters had all their props rotating in the same direction along with many other WW2 multi engine planes like the Mosquito.

I seem to recall the Mossie did use a special Merlin with different rotation?

[Andy48]

8 minutes ago, john davidson 1 said:

I seem to recall the Mossie did use a special Merlin with different rotation?

The one I saw in a museum in Lincolnshire had both props rotating in the same direction as can be seen here:

[john davidson 1]

8 minutes ago, Andy48 said:

The one I saw in a museum in Lincolnshire had both props rotating in the same direction as can be seen here:

Merlin 113 and Merlin 114?

[Andy Gates]

9 hours ago, Paul De Tourtoulon said:

Oh dear then my 4 engine Lancaster is doing it all wrong ! also both my twin engine planes are the same all the engines turn in the same direction,,,

 

No you are not Paul.

 

Personally I consider the contra rotating prop requirement as a myth, it is certainly not a requirement depending on how you fly your machines.

 

IF you take off using the snap to full throttle and yank off the floor technique then yes you will benefit from contra rotating propellers on your motors.

 

IF you fly in a scale manner and gently ease the throttles open during take off then propeller rotations will not make the slightest bit of difference.

 

All my twin engined machines use same rotation props and I have never had any issues with torque or my machines pulling one way or the other.

 

My up and coming winter Lancaster build will not have opposing direction props either and I don't anticipate any issues.