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Radial Engines  
User currently offlineDash8King From Canada, joined Nov 2001, 2742 posts, RR: 11
Posted (11 years 11 months 2 weeks 20 hours ago) and read 3108 times:

Are Radial engines the same as Piston? What are the differences? I know that the DC-3 uses a piston but then people refer to them as Radial engines can anyone help me?

Thanks a lot for putting up with my dumb questions.

15 replies: All unread, jump to last
 
User currently offlineTulsarefueler From United States of America, joined Aug 2002, 41 posts, RR: 0
Reply 1, posted (11 years 11 months 2 weeks 20 hours ago) and read 3067 times:

Radial engine are piston engines. The main difference is the cylinders are in
a circular pattern instead of horizontally opposed or in a V pattern.


User currently offlineL-188 From United States of America, joined Jul 1999, 29791 posts, RR: 58
Reply 2, posted (11 years 11 months 2 weeks 18 hours ago) and read 3059 times:

A radial engine has radial symmetry in it's layout, just like a starfish.

The other two typically are bilaterally symmetric, like humans. One side matches the other.


Seriously though.

looking from the front or the back, the pistons are mounted around the crankshaft in the middle. The engine case is bolted to the airframe and the crank turns the prop.

This is not to be confused with the similar rotary engine. Same basic layout but the crankshaft is bolted to the airplane and the engine case and pistons all spin with the airframe.

The rotary engine was widely used on WWI fighters. It the reason why the Sopwith Camel had a wicked left turn, or was it right? I can't remember.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineTimz From United States of America, joined Sep 1999, 6797 posts, RR: 7
Reply 3, posted (11 years 11 months 2 weeks 2 hours ago) and read 3069 times:

This may not be quite right, but close enough: a piston engine has pistons. You know what they are, right?

But there are lots of different arrangements of piston engines. Your car might have four pistons (in four cylinders) in a row along the crankshaft, with the axes of the cylinders parallel; some aircraft engines used to use that arrangement, but it's fairly rare now. V-6's and V-8's are common in cars but rare in aircraft. Radial engines are just another possible cylinder arrangement of a piston engine.

Maybe 98% (?) of piston engines flying today are air-cooled, unlike your car (probably). That's one reason for the radial arrangement.


User currently offlineLZ-TLT From Germany, joined Apr 2001, 431 posts, RR: 0
Reply 4, posted (11 years 11 months 2 weeks 2 hours ago) and read 3039 times:

To add to Timz's comment:

The Junkers Ju-88 has 18-cylinder Y-form engines(3 banks a 6 cylinders arranged in an Y form around the crankshaft)

While building the Tu-4(B-29 clone), the russians considered the use of their own developed, 48-cylinder X-form engines(4 12-cylinder banks arranged in an X-form around the crankshaft). However, the intention was cancelled due to unreliability and maintenance problems of these experimental engines.

The french pre-WWII Caudron racing aircraft were equipped with straight(not V) Renault 6 or 8-cylinder engines(common in cars, but not that common in aircraft, even in those years)

ALL WWII watercooled engines - the DB series(powering the Me-109), VK-105PF and VK-107PF (all Yak fighters), RR Gryphon/Merlin(Hurricane/Spitfire/Mustang), Allison(Curtiss Kittyhawk), just to mention the most popular ones were V-12's mounted inverted


User currently offlinePPGMD From United States of America, joined Sep 2001, 2453 posts, RR: 0
Reply 5, posted (11 years 11 months 2 weeks 1 hour ago) and read 3032 times:

Well that I know of there is one one readily made radial engine that is the Russian M-14, its gear backwards, so the prop spins the other way, which I think is couter clockwise from the pilots seat. They are used in the Sukoi series of aerobatic airplanes (SU-29 and SU-31), and in the Pitts Model 12 made by home builders. Its a rather fine engine that is much cleaner than the old radials thanks to the clean kit. Oh one intresting thing the starter is powered by air pressure so its not uncommon to see Dive tanks in the hanger. I know that I spent several hours starting one as it neared time to do the certification flights.


At worst, you screw up and die.
User currently offlineL-188 From United States of America, joined Jul 1999, 29791 posts, RR: 58
Reply 6, posted (11 years 11 months 1 week 6 days 23 hours ago) and read 3024 times:

Check that

I wasn't aware that the RR Merlin and Griphon, and Allison 1710 where inverted mounted. I was under the impression the where mounted right side up.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineLZ-TLT From Germany, joined Apr 2001, 431 posts, RR: 0
Reply 7, posted (11 years 11 months 1 week 6 days 20 hours ago) and read 2991 times:

checked it, you're right, L-188.
My fault, pls excuse me


User currently offlineTimz From United States of America, joined Sep 1999, 6797 posts, RR: 7
Reply 8, posted (11 years 11 months 1 week 6 days 3 hours ago) and read 2985 times:

No expert on Ju88s, but I assume 99.9% (or maybe 100%) of them had either BMW 14-cylinder two-row radials or Junkers Jumo inverted V-12s. I think the Jumo 222 that appeared in a few prototypes was a 24-cyl-- 6 banks of 4-in-line.

I'll try another spelling: Griffon?

I guess all Rolls-Royce and Allison V-12s were right-side-up, weren't they? By which we mean the crankshaft was at the bottom of the engine with the cylinder banks forming a 60-degree vee above it-- the usual arrangement, in other words. But German WWII V-12s were all? inverted.


User currently offlineDash8King From Canada, joined Nov 2001, 2742 posts, RR: 11
Reply 9, posted (11 years 11 months 1 week 5 days 23 hours ago) and read 2957 times:

Ok thanks a lot, I now have another question how can you tell by looking at it if it is a piston or a radial engine. Like a C150 is Piston but a DC-3 is Radial so how can you tell by looking at it. BTW, yes I did know what a piston was.

User currently offlinePPGMD From United States of America, joined Sep 2001, 2453 posts, RR: 0
Reply 10, posted (11 years 11 months 1 week 5 days 22 hours ago) and read 2970 times:

If you are looking at the engine itself the engine is like this

The cylinders will be surrounding the the crankshat. If you are looking at the cowling often they are circular with a round vent that is almost unobsructed.

Oh that picture was from a T-28 F or H model has about 1425hp.

Now a piston is well like your car engine. Take a look under the hood of almost any GA plane and you will see it.



At worst, you screw up and die.
User currently offlineDash8King From Canada, joined Nov 2001, 2742 posts, RR: 11
Reply 11, posted (11 years 11 months 1 week 5 days 20 hours ago) and read 2950 times:

Wow ok thanks a lot PPGMD I have all the answers to all the questions I asked so I thank you all for responding and passing on information to me which I am sure I will be able to pass on to someone too.

Thanks Again.


User currently offlineBroke From United States of America, joined Apr 2002, 1322 posts, RR: 3
Reply 12, posted (11 years 11 months 1 week 5 days 14 hours ago) and read 2945 times:

A few notes on radial engines that you may not know.
U.S. radials are designated with the letter "R", the number following the "R" is the approximate displacement in cubic inches.
Pratt & Whitney radials generally have 7 cylinders in each row.
Wright Aeronautical radials generally have 9 cylinders in each row.
There are very few radials with an even number of cylinders in a row; the reason is vibration and resonance problems.
Radial engines are turned over on the starter a couple of times before turning the fuel and ignition "on" to pump any oil that has accumulated in the bottom cylinder(s) out of that cylinder(s). Trying to compress oil on the start is a good way to blow the bottom cylinder (As known as a "Jug") right off the engine.
Oil in the bottom cylinder(s) is also the reason why radials tend to smoke badly during the start.


User currently offlineTimz From United States of America, joined Sep 1999, 6797 posts, RR: 7
Reply 13, posted (11 years 11 months 1 week 5 days 9 hours ago) and read 2920 times:

Assuming the radial engine is a four-stroke cycle (as most are, right?), then if you think about it you'll see that a single-row radial pretty well has to have an odd number of cylinders. Otherwise you can't arrange the power strokes and intake strokes.

User currently offlineIMissPiedmont From United States of America, joined May 2001, 6281 posts, RR: 34
Reply 14, posted (11 years 11 months 1 week 4 days 22 hours ago) and read 2889 times:

And then you can add rotary engines. They are, of course also piston engines. The difference being that a radial has a fixed engine with a moving crankshaft while the rotary has a fixed crankshaft with a moving engine. Confused yet?


Quit calling an airport ramp "Tarmac" and a taxiway "runway".
User currently offlineNightcruiser From , joined Dec 1969, posts, RR:
Reply 15, posted (11 years 11 months 1 week 4 days 6 hours ago) and read 2853 times:

Radial engines are in many ways like piston engines, but radial engines have symmetry.

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