GO480

"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.

I really want that 450hp Allison(!!!) but it would be at least a $250K
upgrade and I have a 80hr engine now. Supposedly it well take off in about
80' with the Allison..

Mike
MU-2


"Jim Burns" wrote in message
...
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.

Jim Burns wrote:
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.

The QueenAir uses supercharged 480's. The unblown engines run about 295HP
I believe.

There's no free lunch. While the gohpers get more HP out of less cubic
inches, the weight doesn't really go down because of the weight of the
gear box. The CG does go forward a bit though.

Mike Rapoport wrote:
I really want that 450hp Allison(!!!) but it would be at least a $250K
upgrade and I have a 80hr engine now. Supposedly it well take off in about
80' with the Allison..

Are you going to put the All-Terrain tires and the air horns on it too?

"Ron Natalie" wrote in message
...
Mike Rapoport wrote:
I really want that 450hp Allison(!!!) but it would be at least a $250K
upgrade and I have a 80hr engine now. Supposedly it well take off in
about 80' with the Allison..

Are you going to put the All-Terrain tires and the air horns on it too?

No, I thought that thing was pretty stupid. The performance was about the
same as a stock Helio after they added 1000lb to the empty weight.

Mike
MU-2

Are you going to put the All-Terrain tires and the air horns on it too?

No, I thought that thing was pretty stupid. The performance was about
the same as a stock Helio after they added 1000lb to the empty weight.

Yeah, but it was soooo cool!

;-)

First train I've ever heard going over at 1000 AGL...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

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

Nathan Young wrote:

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.

Last I read, they were removing most of that, except the turbine that
is... To get better cruise performance... Guess it was fun for awhile
and then became impractical for frequent usage...