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Off Topic - Spruce Goose



 
 
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  #1  
Old January 5th 04, 01:59 PM
Steve Beaver
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Default Off Topic - Spruce Goose

We have all seen the film of the Spruce Goose lifting off the water for a
few seconds only to be retired to its hangar never to fly again but I
wonder, what would its performance have been? Did Hughes determine in that
brief hop that the aircraft was no good or did ecconomic concerns ground it?

There are all kinds of aircraft performance analysis programs available now.
Has anyone ever plugged in the Goose specifications and determined how it
would fly?


  #2  
Old January 5th 04, 05:49 PM
VideoFlyer
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Good question! I've often wondered about that myself.
  #3  
Old January 5th 04, 06:10 PM
Richard Isakson
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"Steve Beaver" wrote ...
We have all seen the film of the Spruce Goose lifting off the water for a
few seconds only to be retired to its hangar never to fly again but I
wonder, what would its performance have been? Did Hughes determine in that
brief hop that the aircraft was no good or did ecconomic concerns ground

it?

I believe he discovered the airplane didn't have enough power to fly out of
ground effect even at empty weight. Others say that he had to fly one time
to collect the money from the contract. In either case, it's been shown
that it wouldn't have flown with a full load.

Rich


  #4  
Old January 5th 04, 06:31 PM
Bill Daniels
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"Richard Isakson" wrote in message
...
"Steve Beaver" wrote ...
We have all seen the film of the Spruce Goose lifting off the water for

a
few seconds only to be retired to its hangar never to fly again but I
wonder, what would its performance have been? Did Hughes determine in

that
brief hop that the aircraft was no good or did ecconomic concerns ground

it?

I believe he discovered the airplane didn't have enough power to fly out

of
ground effect even at empty weight. Others say that he had to fly one

time
to collect the money from the contract. In either case, it's been shown
that it wouldn't have flown with a full load.

Rich

The prototype Hercules used 8 Pratt and Whitney R-4360 of 3500 HP each - the
wrong engines. The 5000 - 7000 HP Lycoming XR7755, then under development,
was the intended engine. The Convair B-36 and the Northrop B-35 were also
supposed to use the R7755. See:
http://www.aviation-history.com/engines/xr-7755.html

With a total of 56,000 HP instead of "just" 28,000 the "Spruce Goose" would
have been a outstanding success - don't blame the failure on the airframe.

It's interesting to speculate how these huge aircraft would have performed
with the enormous Liquid cooled Lycoming.

Bill Daniels

  #5  
Old January 5th 04, 06:52 PM
Rich S.
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"Bill Daniels" wrote in message
link.net...

The prototype Hercules used 8 Pratt and Whitney R-4360 of 3500 HP each -

the
wrong engines. The 5000 - 7000 HP Lycoming XR7755, then under

development,
was the intended engine. The Convair B-36 and the Northrop B-35 were also
supposed to use the R7755. See:
http://www.aviation-history.com/engines/xr-7755.html

With a total of 56,000 HP instead of "just" 28,000 the "Spruce Goose"

would
have been a outstanding success - don't blame the failure on the airframe.

It's interesting to speculate how these huge aircraft would have performed
with the enormous Liquid cooled Lycoming.


Are plans available?

Rich "Sharpening my chisel" S.


  #6  
Old January 5th 04, 07:20 PM
Frank Stutzman
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Bill Daniels wrote:

The prototype Hercules used 8 Pratt and Whitney R-4360 of 3500 HP each - the
wrong engines. The 5000 - 7000 HP Lycoming XR7755, then under development,
was the intended engine. The Convair B-36 and the Northrop B-35 were also
supposed to use the R7755. See:
http://www.aviation-history.com/engines/xr-7755.html


With a total of 56,000 HP instead of "just" 28,000 the "Spruce Goose" would
have been a outstanding success - don't blame the failure on the airframe.


Well, maybe.

According to the website you referanced the R7755 burned 580 gallons per
hour at 5,000 HP. For the Goose that would mean 8*580= 4,640 gallons an
hour or 27,840 pounds an hour. Nothing like burning 13 TONS of fuel an
hour!

However, according to http://www.sprucegoose.org/Specification.htm, the
Goose had a payload of 65 tons (130,000 pounds). It also says that the
cruise speed was supposed to be 175 mph. Lets we were going to fly it
from San Francisco to Honolulu (which seems to me to be a reasonable
mission). We've got a fair tail wind and we are going to get 200 mph
groundspeed. We are going to throttle back to 6 tons an hour. Thats a
2400 mile flight that will take 12 hours and burn 72 tons of fuel. Looks
to me like we were going to need fuel about a hour before we got to
Hawaii.

Now maybe the "payload" number on the sprucegoose website is after full
fuel. Maybe the R7755 were lighter than the R4360. It certainly seems to
me that it was doubtful that the goose could have had met its intended
use.

It's interesting to speculate how these huge aircraft would have performed
with the enormous Liquid cooled Lycoming.


Indeed.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

  #7  
Old January 5th 04, 09:58 PM
L.D.
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Default

Frank Stutzman wrote:

Bill Daniels wrote:



The prototype Hercules used 8 Pratt and Whitney R-4360 of 3500 HP each - the
wrong engines. The 5000 - 7000 HP Lycoming XR7755, then under development,
was the intended engine. The Convair B-36 and the Northrop B-35 were also
supposed to use the R7755. See:
http://www.aviation-history.com/engines/xr-7755.html





With a total of 56,000 HP instead of "just" 28,000 the "Spruce Goose" would
have been a outstanding success - don't blame the failure on the airframe.



Well, maybe.

According to the website you referanced the R7755 burned 580 gallons per
hour at 5,000 HP. For the Goose that would mean 8*580= 4,640 gallons an
hour or 27,840 pounds an hour. Nothing like burning 13 TONS of fuel an
hour!

However, according to http://www.sprucegoose.org/Specification.htm, the
Goose had a payload of 65 tons (130,000 pounds). It also says that the
cruise speed was supposed to be 175 mph. Lets we were going to fly it
from San Francisco to Honolulu (which seems to me to be a reasonable
mission). We've got a fair tail wind and we are going to get 200 mph
groundspeed. We are going to throttle back to 6 tons an hour. Thats a
2400 mile flight that will take 12 hours and burn 72 tons of fuel. Looks
to me like we were going to need fuel about a hour before we got to
Hawaii.

Now maybe the "payload" number on the sprucegoose website is after full
fuel. Maybe the R7755 were lighter than the R4360. It certainly seems to
me that it was doubtful that the goose could have had met its intended
use.



It's interesting to speculate how these huge aircraft would have performed
with the enormous Liquid cooled Lycoming.



Indeed.



I don't know if it is true or just hanger talk but I've always heard
that aeronautical engineers say it is impossible for a bumble bee to
fly. However we all know they do it well. I would like for someone to
plug in aircraft performance analysis programs a bubble bees
specifications and see if it is possible for him to fly. OH well it
probably won't work because a bumble bee isn't an aircraft, or is he?

  #8  
Old January 6th 04, 01:16 AM
BlakeleyTB
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Default

The Hughes Flying Boat was intended to fly in ground effect.
  #9  
Old January 6th 04, 02:09 AM
Ed Wischmeyer
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Default

The Hughes Flying Boat was intended to fly in ground effect.

Wow, never heard that before!! What's the reference?

thanks

Ed Wischmeyer
  #10  
Old January 6th 04, 02:12 AM
Bill Daniels
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Posts: n/a
Default


"Frank Stutzman" wrote in message
...
Bill Daniels wrote:

The prototype Hercules used 8 Pratt and Whitney R-4360 of 3500 HP each -

the
wrong engines. The 5000 - 7000 HP Lycoming XR7755, then under

development,
was the intended engine. The Convair B-36 and the Northrop B-35 were

also
supposed to use the R7755. See:
http://www.aviation-history.com/engines/xr-7755.html


With a total of 56,000 HP instead of "just" 28,000 the "Spruce Goose"

would
have been a outstanding success - don't blame the failure on the

airframe.

Well, maybe.

According to the website you referanced the R7755 burned 580 gallons per
hour at 5,000 HP. For the Goose that would mean 8*580= 4,640 gallons an
hour or 27,840 pounds an hour. Nothing like burning 13 TONS of fuel an
hour!

However, according to http://www.sprucegoose.org/Specification.htm, the
Goose had a payload of 65 tons (130,000 pounds). It also says that the
cruise speed was supposed to be 175 mph. Lets we were going to fly it
from San Francisco to Honolulu (which seems to me to be a reasonable
mission). We've got a fair tail wind and we are going to get 200 mph
groundspeed. We are going to throttle back to 6 tons an hour. Thats a
2400 mile flight that will take 12 hours and burn 72 tons of fuel. Looks
to me like we were going to need fuel about a hour before we got to
Hawaii.

Now maybe the "payload" number on the sprucegoose website is after full
fuel. Maybe the R7755 were lighter than the R4360. It certainly seems to
me that it was doubtful that the goose could have had met its intended
use.

It's interesting to speculate how these huge aircraft would have

performed
with the enormous Liquid cooled Lycoming.


Indeed.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR


I suspect the 580 GPH is a gross error. Assuming a Specific Fuel
Consumption of 0.42 Lbs./HP/Hr., The R7755 would have "only" used 2100
pounds per hour at 5000 HP output. Assuming 70% power at cruise the fuel
consumption drops to 1470 PPH.

If the engine had been developed to put out 7000 HP and the SFC came in at
0.40, the 70% cruise fuel burn would have been 1,960 PPH. All eight
engines would burn 15,680 PPH or "only" 7.84 Tons per hour.

Given the liquid cooling, variable cam timing and gear box the SFC might
have been even lower.

Bill Daniels

 




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