another radial question

[Tater]

after looking at all the planes in the oshkosh museum, I saw a few
radials where the crank was stationary, and the rest of the engine
moved with the prop.

which brought me to this question. why did they use radials? some of
the first planes used inline engines, nut for some reason radials came
into play.

[Capt. Geoffrey Thorpe]

"Tater" > wrote in message
oups.com...
> after looking at all the planes in the oshkosh museum, I saw a few
> radials where the crank was stationary, and the rest of the engine
> moved with the prop.
>
> which brought me to this question. why did they use radials? some of
> the first planes used inline engines, nut for some reason radials came
> into play.
>

Good cooling with all the cylinders whirling in the breeze.

BTW: They are called "rotary" engines - "radials" have stationary cylinders
(but are also easier to cool)

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[[email protected]]

On Sep 22, 6:02 pm, "Capt. Geoffrey Thorpe" <The Sea Hawk at wow way
d0t com> wrote:
> "Tater" > wrote in message
>
> oups.com...
>
> > after looking at all the planes in the oshkosh museum, I saw a few
> > radials where the crank was stationary, and the rest of the engine
> > moved with the prop.
>
> > which brought me to this question. why did they use radials? some of
> > the first planes used inline engines, nut for some reason radials came
> > into play.
>
> Good cooling with all the cylinders whirling in the breeze.
>
> BTW: They are called "rotary" engines - "radials" have stationary cylinders
> (but are also easier to cool)
>
> --
> Geoff
> The Sea Hawk at Wow Way d0t Com
> remove spaces and make the obvious substitutions to reply by mail
> When immigration is outlawed, only outlaws will immigrate.

Radials have a short, stiff crank, which keeps the weight
down. All the cylinders (in a single-row radial) get lots of cooling
air. On old airplanes the whole engine was out in the breeze. No cowl,
no baffles, no nothing. Light and cheap.

Dan

[Morgans[_2_]]

"Tater" > wrote

> which brought me to this question. why did they use radials? some of
> the first planes used inline engines, nut for some reason radials came
> into play.

Reasons for widespread use of radials

#10 Simplicity
#9 Durability
#8 Reliability
#7 Ease of repair
#6 Able to take battle damage without quitting
#5 Ease of repair after #6 occurs
#4 Weight
#3 Weight
#2 Weight
#1 Savings of all the above Weight
--
Jim in NC

[James Sleeman]

On Sep 23, 11:57 am, Tater > wrote:
> after looking at all the planes in the oshkosh museum, I saw a few
> radials where the crank was stationary, and the rest of the engine
> moved with the prop.

An engine with all the clyinders spinning around a stationary crank
(and the prop bolted onto the engine) is called a Rotary engine.
World-war-one vintage stuff.

The main reasons for thier usage in those early times was that the
engines of the time were big, inefficient, and rotated slowly, this
meant a couple of things, first is that they needed good cooling (esp
when the aircraft was on the ground) and second is that a plain radial
of the time (rotating crank) would introduce lots of nasty power-pulse
vibration due to the slow running and large combustion strokes. With
a rotary, the engine itself becomes an *enormous* flywheel which both
provides cooling for the cylinders even if the aircraft is stationary,
and also smooths out the power.

The big disadvantage is you effectively have built a massive gyroscope
onto the front of your plane, which radically affects the handling, if
you move with the gyro then the effect can be used to your advantage
(if it doesn't take you by surprise first!), but that big engine only
spins in one direction so moving against the gyro causes some issues.
And of course when you open the throttle and the engine starts
spinning faster, your whole plane is going to have a very distinct
notion to roll over with the engine.

As engine technology improved (fairly rapidly), the advantage of a
rotary (spinning engine) over a radial (spinning crank) waned and
radials took over.

Radials are not common in modern aircraft having been surplanted by
inline engines, however they do still find favour in certain
applications (bush flying for example) due to thier relative
simplicity and therefore reliability (if treated right).

[Tater]

On Sep 22, 6:57 pm, Tater > wrote:
> after looking at all the planes in the oshkosh museum, I saw a few
> radials where the crank was stationary, and the rest of the engine
> moved with the prop.
>
> which brought me to this question. why did they use radials? some of
> the first planes used inline engines, nut for some reason radials came
> into play.

hey, thanks for all the replies, but it brings up one more
question.....

why don't we use radials now?

[[email protected]]

On 26 Sep, 01:30, Tater > wrote:
> On Sep 22, 6:57 pm, Tater > wrote:
>
> > after looking at all the planes in the oshkosh museum, I saw a few
> > radials where the crank was stationary, and the rest of the engine
> > moved with the prop.
>
> > which brought me to this question. why did they use radials? some of
> > the first planes used inline engines, nut for some reason radials came
> > into play.
>
> hey, thanks for all the replies, but it brings up one more
> question.....
>
> why don't we use radials now?

For lower power engines the air cooled flat 4/6 has
turned out to be the winner. higher power
requirements are best met with a gas turbine.

I think that the smallest turbines in widespread use
are about 400hp.

Smaller ones do exist:-

http://www.youtube.com/watch?v=OVxeZYdVRLM

http://www.jet-man.com/actuel_eng.html

[Mike Granby]

> why don't we use radials now?

Lubrication is a messy business, AIUI.

[Bertie the Bunyip[_19_]]

Tater > wrote in news:1190766611.292026.287600
@g4g2000hsf.googlegroups.com:

> On Sep 22, 6:57 pm, Tater > wrote:
>> after looking at all the planes in the oshkosh museum, I saw a few
>> radials where the crank was stationary, and the rest of the engine
>> moved with the prop.
>>
>> which brought me to this question. why did they use radials? some of
>> the first planes used inline engines, nut for some reason radials came
>> into play.
>
> hey, thanks for all the replies, but it brings up one more
> question.....
>
> why don't we use radials now?
>

I do, why don';t you?

Bertie

[Paul kgyy]

> why don't we use radials now?

The large frontal area produces more drag (lower airspeed), and note
the statements above about reliability "if treated right". They also
limit forward visibility to some extent.

Having said that, they are still used a lot. I've heard that one nice
thing about radials is instant power response.

[Morgans[_2_]]

"Paul kgyy" <> wrote

> Having said that, they are still used a lot. I've heard that one nice
> thing about radials is instant power response.

Humm, not quite what I have heard.

Like all geared engines, (most radials do have the shaft speed reduced
though gearing, I believe) you have to roll the power on smoothly, if you
want them to last.
--
Jim in NC

[[email protected]]

On Sep 26, 9:45 am, "Morgans" > wrote:
> "Paul kgyy" <> wrote
>
> > Having said that, they are still used a lot. I've heard that one nice
> > thing about radials is instant power response.
>
> Humm, not quite what I have heard.
>
> Like all geared engines, (most radials do have the shaft speed reduced
> though gearing, I believe) you have to roll the power on smoothly, if you
> want them to last.
> --
> Jim in NC

Lots, but not most, I don't think. Except for the small
Russian radials, gearing is usually found in the larger engines.

Dan

[Morgans[_2_]]

<Dan_Thomas_> wrote
>
> Lots, but not most, I don't think. Except for the small
> Russian radials, gearing is usually found in the larger engines.

How about the P&W R-985, the Wasp Junior? Was that geared?

That engine comes to mind, because it was the common engine on the Beaver
bushplanes.

It would be interesting (to me, at least) to see a list of the most common
radial engines, and see which are geared, or not. I have no idea if a list
such as that exists, or where it would be found. Anyone?
--
Jim in NC

[Matt Barrow[_4_]]

> wrote in message
oups.com...

>
> Lots, but not most, I don't think. Except for the small
> Russian radials, gearing is usually found in the larger engines.
>

http://www.radialengines.com/faq_section/index.htm#q3

Pretty pictures! Piston / Crank Arrangement


--
Matt Barrow
Performance Homes, LLC.
Cheyenne, WY