Welcome Guest. Sign in or Signup

2 Answers

Why is the throttle open 1/4inch when start up engine C172

Asked by: 506 views , ,
Aircraft Systems, Student Pilot

Hi..

I'm progress in PPL in South Korea.

My question is 'Why is the throttle open 1/4inch when start up engine C172'

Of course, it need open the throttle open for smooth start engine. but why 4/1 inch?

There are many option, like a 3/1 inch or 5/1 inch.

I don't know why specific length of open throttle. Thx.

 

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

2 Answers

  1. Best Answer


    Russ Roslewski on Apr 13, 2017

    There’s no magic to 1/4 inch. 1/3 inch, 1/5 inch, 1/2 inch will all work just fine. The idea is you just have to have the throttle open “a little”. But since everybody’s definition of “a little” is different, they give you a number – 1/4 inch.

    I have yet to have anybody measure it before starting, so your estimate of 1/4 inch is likely different from mine. But if the engine starts, it was good enough.

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes



  2. John Scarry on Apr 13, 2017

    The next time you fly, pay attention to where the throttle is when you taxi at normal speed, do your runup, and when idling at 800-1000′ RPM. My guess is that at 800 RPM the throttle is about ¼”. If you start the engine with the throttle where it would be for runup, you would start up at ~1700 RMP. Not good.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.