GO480

When I read about Lycoming engines the terms "wide deck", "narrow deck",
"straight valve" and angle valve are used to describe different
cylinder/case configurations. What is the GO480 in my Helio Courier?
Narrow deck? Wide deck? Angle valve? Straight valve?

Thanks

Mike
MU-2

Mike Rapoport wrote:
When I read about Lycoming engines the terms "wide deck", "narrow deck",
"straight valve" and angle valve are used to describe different
cylinder/case configurations. What is the GO480 in my Helio Courier?
Narrow deck? Wide deck? Angle valve? Straight valve?

The deck refers to the flange where the cylinder meets the case.
The valves straight/angle indicate whether the two rockers are
parallel to each other or form a sort of V). I don't know about
the deck, but I think the Gopher's were all angle-valve. The
wide deck engine serial numbers end in "A".

Intresting information about all this can be obtained at
www.sacskyranch.com.

My condolences on having the gopher80. Getting rid of mine
was a big improvement on the Navion.

-Ron

Margy wrote:

My condolences on having the gopher80. Getting rid of mine
was a big improvement on the Navion.

Yeah, but it took you nearly two years, didn't it?

George Patterson
Why do men's hearts beat faster, knees get weak, throats become dry,
and they think irrationally when a woman wears leather clothing?
Because she smells like a new truck.

George Patterson wrote:
Margy wrote:


My condolences on having the gopher80. Getting rid of mine
was a big improvement on the Navion.


Yeah, but it took you nearly two years, didn't it?

George Patterson
Why do men's hearts beat faster, knees get weak, throats become dry,
and they think irrationally when a woman wears leather clothing?
Because she smells like a new truck.
More than that, but we got into a bad case of the "might as wells"

Margy

"Margy" wrote in message
...
Mike Rapoport wrote:
When I read about Lycoming engines the terms "wide deck", "narrow deck",
"straight valve" and angle valve are used to describe different
cylinder/case configurations. What is the GO480 in my Helio Courier?
Narrow deck? Wide deck? Angle valve? Straight valve?

The deck refers to the flange where the cylinder meets the case.
The valves straight/angle indicate whether the two rockers are
parallel to each other or form a sort of V). I don't know about
the deck, but I think the Gopher's were all angle-valve. The
wide deck engine serial numbers end in "A".

Intresting information about all this can be obtained at
www.sacskyranch.com.

My condolences on having the gopher80. Getting rid of mine
was a big improvement on the Navion.

-Ron

What was the problem with the GO480? In the Helio, it is considered much
better than the TIO540 or the IO720.

Mike
MU-2

Mike Rapoport wrote:


What was the problem with the GO480? In the Helio, it is considered much
better than the TIO540 or the IO720.


The thing is obsolete. Lycoming practically denies having made it (they
do deny having made the Gopher35). The TBO and Overhaul costs will kill
you. The accessories are unobtainable in many cases.

Mike,

Just a few questions and thoughts, mainly because I'm curious.

I'd be interested to know the HP rating of the GO480 installed in the Helio.
I've been watching a few people that are building Bearhawks and one article
mentions that the GO480 isn't favored for that application for the relative
high weight to HP ratio compared to the 540.

I "believe" that the Beech Queen Air originally used a version of the 480
and I "know" a lot of them have been retrofitted with either 720's or
turbines. Whether this was due to high rebuild or maintenance costs or lack
of power, I have no idea.

Would the desirability of the 480 in the Helio be due to a desire to keep
them "original"?

Jim


"Mike Rapoport" wrote in message
ink.net...

"Margy" wrote in message
...
Mike Rapoport wrote:
When I read about Lycoming engines the terms "wide deck", "narrow
deck",
"straight valve" and angle valve are used to describe different
cylinder/case configurations. What is the GO480 in my Helio Courier?
Narrow deck? Wide deck? Angle valve? Straight valve?

The deck refers to the flange where the cylinder meets the case.
The valves straight/angle indicate whether the two rockers are
parallel to each other or form a sort of V). I don't know about
the deck, but I think the Gopher's were all angle-valve. The
wide deck engine serial numbers end in "A".

Intresting information about all this can be obtained at
www.sacskyranch.com.

My condolences on having the gopher80. Getting rid of mine
was a big improvement on the Navion.

-Ron

What was the problem with the GO480? In the Helio, it is considered much
better than the TIO540 or the IO720.

Mike
MU-2

"Jim Burns" wrote in message
...
Mike,

Just a few questions and thoughts, mainly because I'm curious.

I'd be interested to know the HP rating of the GO480 installed in the
Helio.
I've been watching a few people that are building Bearhawks and one
article
mentions that the GO480 isn't favored for that application for the
relative
high weight to HP ratio compared to the 540.

295HP


I "believe" that the Beech Queen Air originally used a version of the 480
and I "know" a lot of them have been retrofitted with either 720's or
turbines. Whether this was due to high rebuild or maintenance costs or
lack
of power, I have no idea.

Would the desirability of the 480 in the Helio be due to a desire to keep
them "original"?


No, Helio owners only care about STOL performance. The Helio requires high
power for takeoff only. Actually what it requires is high static thrust and
it benefits from a large diameter prop so that thrust flows over more of the
slats/wing/flaps. The geared engine can use a larger diameter prop without
the tips going supersonic. Once airborn, the airplane is not going to go
very fast (135-140kts) with its large wing and large exposed wheels no
matter how much power is availible.

The 350hp TIO 540 tends to overheat in the Helio probably due to the
cowling/baffling design. There were only about seven Helios made with the
TIO540 and at least three seem to be on the market at any given time, a dead
giveaway that the airplane is a lemon..

The 400hp IO 720 adds a lot of weight both in terms of the engine itself and
the additional fuel it requires.

Both the H700 and H800 (350hp and 400hp) were also designed to accomodate
both nosewheel and tailwheel configurations and they are heavier as a
result.

I was surprised that this was the case since generally later airplanes are
improved over earlier ones with various bugs fixed. MU-2s underwent a
gradual transformation over the ~20 yr production run where they got more
power, more pressurization, more fuel capacity, better avionics ect. I went
to OSH last year specifically to find out why all the experienced Helio
pilots preferred the H295 (295hp) to the H700 (350hp) and H800 (400hp). The
explanations varied somewhat but everyone thought strongly that the earlier
ones were better.

The ultimate Helio is a early model with an Allison turbine engine. I know
of only one that exists. This give you a larger prop, much more power AND
lighter weight, although fuel consumption eats up some of the weight
savings.

Mike
MU-2

Thanks Mike!
Great explaination of desired airflow vs. HP.
Several years ago our aerial applicators mounted gearboxes and longer props
to their round engined Air Tractors. Not only did they reduce the prop
speed and noise but they increased the airflow around the airplane
produceing a better spray pattern.

Jim


No, Helio owners only care about STOL performance. The Helio requires
high
power for takeoff only. Actually what it requires is high static thrust
and
it benefits from a large diameter prop so that thrust flows over more of
the
slats/wing/flaps. The geared engine can use a larger diameter prop
without
the tips going supersonic. Once airborn, the airplane is not going to go
very fast (135-140kts) with its large wing and large exposed wheels no
matter how much power is availible.

On Wed, 22 Jun 2005 21:04:19 GMT, "Mike Rapoport"
wrote:

The ultimate Helio is a early model with an Allison turbine engine. I know
of only one that exists. This give you a larger prop, much more power AND
lighter weight, although fuel consumption eats up some of the weight
savings.

I seem to recall a Sport Aviation article about a Helio or similar
STOL plane converted to turbine. The owners put a lot of crazy
conversions onto the plane. For example, they had a train whistle
driven by bleed air from the engine, a sprayer/fogger system for
killing mosquitos in the area prior to landing, and tires that looked
to be from a 4x4 truck.

One hell of a back country airplane.

-Nathan