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"pushing" Vs "pulling" Props  
User currently offlineBa97 From Canada, joined Apr 2004, 377 posts, RR: 0
Posted (9 years 9 months 1 day 1 hour ago) and read 2195 times:

Please excuse my naivete on this:
Is there any engineering design reason why props are on the front of the plane or engine on commercial aircraft, thus "pulling" compared to backwards facing and "pushing". I have seen pictures of some military planes (German I think) and small private planes with a prop on the rear of the plane. With the overwhelming majority on the front, I expect there is a definite reason but then why the oddities?



there is economy class, business class, first class...then Concorde..pure class
6 replies: All unread, jump to last
 
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 1, posted (9 years 9 months 1 day 1 hour ago) and read 2156 times:

While I am not 100% sure, I would say the main problem is weight distribution. Before long propshafts were feasible, putting the prop in the ass of the plane was not possible because the weight distribution would be off with an engine mounting behind the wing. With wing mounted props (as with wing mounted jets), you want the weight to be on the front of the wing to decrease the tendency of the wing to twist up.

As far as I have been able to discern from previous discussions of pushers on this forum, they are theoretically as efficient as pullers.

Problem #2: Air AFTER the plane is more turbulent. Pullers get less turbulent air and so can be more efficient. I'm not entirely sure about this one.

Problem #3: At least in smaller fighters, the pilots don't enjoy bailing out only to be chopped to pieces by their own prop.

The German plane you are referring to is probably the Do-335 Pfeil. Yes, it had a pusher prop and rear engine, but it ALSO had a nose prop and front engine. Very cool plane http://www.aeroflight.co.uk/profile/d335top.htm. The Pfeil resolved the bailout problem by having a jettisonable prop and fin.




"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineL-188 From United States of America, joined Jul 1999, 29705 posts, RR: 59
Reply 2, posted (9 years 9 months 16 hours ago) and read 1848 times:

All other things being equal a pusher prop won't be as efficent because of the turbulent air comming off the wing, Nacelle, or cabin ahead of it.

There is also issues of prop clearence on take-off, prop damage from rocks kicked up by the mainwheels.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineMD-90 From United States of America, joined Jan 2000, 8494 posts, RR: 12
Reply 3, posted (9 years 9 months 15 hours ago) and read 1830 times:

Also prop damage from things flying off the engine, and the fact that they can be hard to cool.

But for some designs it makes good sense.



Practicality (Progressive Aerodyne Searey)



Weight distribution (Piaggio P.180 Avanti)


User currently offlineCanoecarrier From United States of America, joined Feb 2004, 2828 posts, RR: 12
Reply 4, posted (9 years 8 months 4 weeks 11 hours ago) and read 1698 times:

I've always been a fan of the Cessna 337, with both a pusher and a puller. IIRC, you do a seperate multi checkride since it has counter rotating props.


The beatings will continue until morale improves
User currently offlineAlessandro From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 8 months 4 weeks 8 hours ago) and read 1669 times:

Also the Beechcraft "starship" got the pulling props..


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 6, posted (9 years 8 months 3 weeks 6 days 18 hours ago) and read 1611 times:

Shouldn't that be pushing?


"There are no stupid questions, but there are a lot of inquisitive idiots."
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