A stupid question

Member for

16 years 3 months

Posts: 8,505

OK folks here is another of my periodical stupid questions. It concerns the fitting of the spring on the throttle of Rotax engines. 1: Why is it set up to apply power if the throttle friction is not tightened? Surely anything that requires the throttle halnd being somewhere else is a reason for the throttle to close rather than open. 2: Why is the spring so powerful that when the throttle friction is tight enough to prevent unwanted movement it is almost a two handed job for a Gorilla to make wanted movements. As I said stupid questions but as I'm only an armchair pilot I don't know the answers.
Original post

Member for

13 years

Posts: 8,832

No question is stupid..... Most piston engined aircraft have a spring on them, mostly on the carb, this is a fail safe........ Imagine if you were flying along, pulled the throttle closed to say descend at Air traffics request to a different height and the throttle cable snaps, there you would be, descending at idle with no power and nowhere to go to but the crash site, the spring comes into play and takes the carb to full throttle...... better having all the power than none, so to speak....... :)

Member for

16 years 3 months

Posts: 8,505

Aha, now I understand, thank you, but that still doesn't help to answer part 2. Surely it doesn't need to be so strong that you need to be Hercules to make deliberate throttle adjustments when the friction nut is tight enough to prevent accidental movement. I'm glad I came to this forum years ago as I have improved my knowledge of things aviation no end thanks to the many people on here who thinks the same way we do. No question is stupid because if you don't ask you don't learn. I sometimes think that some of the questions (like this one) could have been answered by the posterif they had applied some logic and given it a bit more thought. My question certailnly falls into that category. As you say too much power is far better than none at all.

Member for

8 years 7 months

Posts: 6,467

Mike, Tony T is right. I run a Rotax 912 and a fine engine it is. I am though slightly puzzled by my particular set-up unless, of course, they are all the same. The left seat has a spring loaded throttle which, as you correctly state, requires a gorilla to work it! The right seat however has a different throttle arrangement being a rigid quarter inch diameter rod connecting the throttle handle to the carb. The benefit of this arrangement is that if the spring breaks on the left side, the right hand pilot/passenger or indeed the left hand pilot can lean across and continue to operate the throttle normally. John Green

Member for

16 years 3 months

Posts: 8,505

Curious. It makes you wonder sometimes where these odd ideas come from.