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New question twin engine setup.... Help please

#1
Hi all... I need a bit of help.. Im building the bronco (twin c motors) and the video instructions were using old motors...


So... 1) do I use the 'x' brace between firewall and motor

15919029423067896893489008308913.jpg

or does the X brace go inside the firewall?

15919029909302510103076207678610.jpg


2) im running a str8 setup.. No differential thrust.. Are both motors turning ccw (regular) with cw props or is 1 cw and one ccw?

Ty!

Z
 

Merv

Well-known member
#3
Im building the bronco (twin c motors) and the video 1) do I use the 'x' brace between firewall and motor
Yes, it is optional. Sometimes I don't use the X at all, just attach the motor directly to the firewall. Whichever way is easier for you.

or does the X brace go inside the firewall?
No, on the outside.

2) Are both motors turning ccw (regular) with cw props or is 1 cw and one ccw?
In a twin setup, it's best to have one go CW & one CCW. This is to offset the torque effect of each motor. Most twins have the props go downwards as they pass the fuse
 
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#4
Yes, it is optional. Sometimes I don't use the X at all, just attach the motor directly to the firewall. Whichever way is easier for you.

No, on the outside.

In a twin setup, it's best to hae one go CW & one CCW. This is to offset the torque effect of each motor. Most twins have the props go downwards as they pass the fuse

"Most twins have the props go downwards as they pass the fuse" <--- what does this mean?.

Ty again!

Z
 

Merv

Well-known member
#5
"Most twins have the props go downwards as they pass the fuse" <--- what does this mean?.
Counter-rotating propellers generally spin clockwise on the left engine and counter-clockwise on the right. They will go downward as they pass the fuse. If the motors switch sides, the props will go upward as they pass the fuse.

Set them up like this.
 
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#8
Got it... Matching hq props... BTW here it is... IMG_20200612_180033.jpg
Counter-rotating propellers generally spin clockwise on the left engine and counter-clockwise on the right. They will go downward as they pass the fuse. If the motors switch sides, the props will go upward as they pass the fuse.

Set them up like this.

Thank you merv... Picture helped and now I understand the fuse reference!

-z
 

quorneng

Well-known member
#9
Zeligman
Your twin looks very nice.
There is a technical reason why prop rotation is done that way, particularly on high powered full size. Should an engine fail the motor torque of the good engine tries to 'lift' the dead engine wing so it makes full power flying on one a bit easier. The same also applies to models which tend to be relatively even higher powered but it does take some quick action on the controls to keep things in shape. Fortunately electric motors are very reliable. ;)
The best known example of a high powered twin having props going outwards is the P38 Lightning. It was done that way to cure a tail buffet problem but it made an engine failure just after take off very tricky indeed. It killed many inexperienced pilots before the correct engine fail procedures were worked out.
 
#11
Zeligman
Your twin looks very nice.
There is a technical reason why prop rotation is done that way, particularly on high powered full size. Should an engine fail the motor torque of the good engine tries to 'lift' the dead engine wing so it makes full power flying on one a bit easier. The same also applies to models which tend to be relatively even higher powered but it does take some quick action on the controls to keep things in shape. Fortunately electric motors are very reliable. ;)
The best known example of a high powered twin having props going outwards is the P38 Lightning. It was done that way to cure a tail buffet problem but it made an engine failure just after take off very tricky indeed. It killed many inexperienced pilots before the correct engine fail procedures were worked out.
Very interesting example.. I did not know that about the p38. Ty!