If the 'Spruce Goose' could fly, how effective would it have been ?

[Shortround6]

Well, they were loading up Boeing 314s, Coronados and a few Empire flying boats and doing just that, weather permitting of course. The US Navy ordered 20 Martin Mars aircraft and the British even went for the Short Shetland and even post war the Saunders-Roe Princess.

Events and development of land based aircraft and the proliferation of long runways around the world spelled the end of the flying boats but the need for specially trained crews and the hazards of operation (keeping landing/take off areas clear of floating debris) would have kept their numbers small or lead to theri end in any case.

 

[davparlr]

'Fraid I think the Spruce was a nonsense idea. So you load the thing up with hundreds of soldiers in the middle of winter,

verses 1000s in a slow freighter in torpedo infected water.

somehow manage to get airborne (let's assume it could manage that feat)

I am not sure why you said this given the H-4 had half the wing loading and more power to weight than the B-36. It should have flown quite easily.

 

[GrauGeist]

'Fraid I think the Spruce was a nonsense idea. So you load the thing up with hundreds of soldiers in the middle of winter, somehow manage to get airborne (let's assume it could manage that feat) and then trundle for hours over the wintery Atlantic (with ice and storms galore), the poor pilots are then supposed to land the thing when they reach dear old Blighty, with all the joys of winter storms? There are way too many imponderables there for it to be employed successfully, and that's ignoring the fact that, by the middle of the war, the writing was on the wall for large flying boats for either military or civilian applications. Shame really 'cos it was actually a clean, graceful looking aircraft.

If the weather was going to be poor to hazardous, they usually diverted or cancelled flights, but they did fly aircraft along the North Atlantic route constantly during the war.

Why wouldn't it get airborne? Even though it's max load rating was 400,000 pounds, it was well designed and had 8 R-4360 radials pumping out 4,000 horses each, to get the job done.

In contrast, the Bv222 had a max load of 100,000 pounds with only 6 deisel engines rated at 1,000 hp each and the Mars had a max load of 90,000 pound with just 4 2,500 hp radials.

It's just too bad the "Goose" never got a chance to show off what it could do...

 

[robwkamm]

if they strapped 10 r3350 radial on her she would not be around today. think wood,dope and a highly prone to fire engine.

 

[buffnut453]

If the weather was going to be poor to hazardous, they usually diverted or cancelled flights, but they did fly aircraft along the North Atlantic route constantly during the war.

True, but those aircraft had a nice, solid,terra firma-based runway to land on. You'd need specially cleared landing areas in the sea (or a large lake) for a beast the size of the Spruce. It doesn't take much in the way of choppy waves to ruin a seaborne landing, particularly at high load weights or uneven distribution of the load that would lead to potentially destructive stresses on the airframe.

Why wouldn't it get airborne? Even though it's max load rating was 400,000 pounds, it was well designed and had 8 R-4360 radials pumping out 4,000 horses each, to get the job done.

This gets back to the question of whether the first flight was an accident or intentional. If the latter, then it truly struggled to get airborne. The problem with seaplanes is the "suckiness" of the water. If the design of the hull is wrong, the thing will never get airborne no matter how much power was available from the engines. Just because an aircraft is designed to do something is no proof that it could actually do it on a real mission.

 

[buffnut453]

Well, they were loading up Boeing 314s, Coronados and a few Empire flying boats and doing just that, weather permitting of course. The US Navy ordered 20 Martin Mars aircraft and the British even went for the Short Shetland and even post war the Saunders-Roe Princess.

Events and development of land based aircraft and the proliferation of long runways around the world spelled the end of the flying boats but the need for specially trained crews and the hazards of operation (keeping landing/take off areas clear of floating debris) would have kept their numbers small or lead to theri end in any case.

Agreed, Shortround, but the types you mention weren't carrying hundreds of troops, which leads back to the "all the eggs in one basket" argument. There were just too many risks associated with flying a behemoth the size of the Spruce. Your points about the Shetland and the SaRO Princess reinforce my point that, by mid-WWII, the writing was on the wall for seaplanes because of the large numbers of airfields that were built all over the world during the conflict.

 

[drgondog]

I don't really buy 'accidental' based on achieving a little two much taxi speed. There is a huge difference in allowable taxi speed in Long Beach harbor and rotation speed.

In one sense it could have been filed as a taxi trial (but why) and Hughes just let his sheer exuberance of flying take over..

 

[FLYBOYJ]

If I'm not mistaken I think part of the contract for the Spruce Goose was to have a flyable prototype available on a specified delivery date. Of course Hughes was 3 years behind schedule and a senate hearing on the project occurred a few months earlier where Hughes was accused of wasting taxpayers' money and that the aircraft would never fly. At that time I believe he made his famous statement about putting his reputation into this project and if it did not fly he would leave the country and never come back.

Well it did fly. I don't know other details of the contract but it's obvious that Hughes never turned the aircraft over to the US government. Bottom line, aside from being 3 years behind schedule it seems Hughes met his contract.

That flight was no accident - Hughes knew exactly what he was doing and the concept "could have" worked if the aircraft was developed a few years earlier and if it was operated in an area where there would be no contact with enemy aircraft. I believe it would have been a maintenance nightmare, but the concept was verified.

 

[Milosh]

More than a few a/c have become airborne during fast taxi trials. Iirc the Vulcan did so just recently.

 

[FLYBOYJ]

The problem with seaplanes is the "suckiness" of the water. If the design of the hull is wrong, the thing will never get airborne no matter how much power was available from the engines. Just because an aircraft is designed to do something is no proof that it could actually do it on a real mission.

I have flown in sea planes and float planes and I can tell you that there is no "suckiness" when you establish proper pitch and take off speeds, if anything taxi can be difficult in calm waters because of momentum and the lack of drag under the waterline because you don't have a propeller or drive train on the hulls as seen on a boat. I can assure you that a float plane or sea plane designer is going to make darn sure their hull is going to work before metal is cut. The only time you're going to experience any type of "suckiness" as you call it is if one doesn't maintain proper pitch and airspeeds during take offs and landings.

In the case of the Spruce Goose, the fact that it left it's stable and actually flew was more than proof ot met most, if not all of its design criteria. There would have been other factors to be tested (payload capability, range etc.) but I would guess the possibilites would have been great that these requirements could have been met.

 

[davparlr]

True, but those aircraft had a nice, solid,terra firma-based runway to land on. You'd need specially cleared landing areas in the sea (or a large lake) for a beast the size of the Spruce. It doesn't take much in the way of choppy waves to ruin a seaborne landing, particularly at high load weights or uneven distribution of the load that would lead to potentially destructive stresses on the airframe.

A comparison with some contemporary seaplanes that were successfully operated:

H-4
Power to weight .08 hp/lb
Wing loading 35 lb/sqft

PB2Y
P/W .07 hp/lb
WL 38 lb/sqft

PBM
P/W .064 hp/lb
WL 37 lb/sqft

BV 222
P/W .072 hp/lb
WL 36 lb/sqft


From this simple data the H-4 should have needed less takeoff distance than any of these aircraft.

This gets back to the question of whether the first flight was an accident or intentional. If the latter, then it truly struggled to get airborne. The problem with seaplanes is the "suckiness" of the water. If the design of the hull is wrong, the thing will never get airborne no matter how much power was available from the engines. Just because an aircraft is designed to do something is no proof that it could actually do it on a real mission.

I am not sure we know what power levels Hughes was using during this run. Also, seaplane hull design was quite mature at this time and there is no indication the H-4 design was flawed. It did break the water and seemed to do it very smoothly.

I do not see any reason the H-4 would not have been successful. All of its design criteria fell within, or better than, the norm of other successful seaplane designs.

 

[FLYBOYJ]

More than a few a/c have become airborne during fast taxi trials. Iirc the Vulcan did so just recently.

So did the first F-16

 

[davparlr]

And also Gloster's first jet the E.28/39.

 

[buffnut453]

Hang on a second. The thing got airborne for a few seconds on what may, or may not, have been a high-speed taxi run. How does that possibly equate to evidence it could meet all of its performance requirements? Stall characteristics, handling, trimming for unbalanced loads, maximum speeds - none of these had been remotely examined.

The "suckiness" i was referring to was in comparison to a conventional land-based aircraft - sorry for my use of non-technical words. However, overcoming hydrodynamic drag is critical and mistakes are made in designs. I agree the design of floatplane hulls was well understood but the hydrodynamic properties of the Spruce were never fully explored. For example, the Bv138 was completely redesigned, including a new planing hull, after early versions lacked performance.

The safe operation of the Spruce would have presented massive challenges, not least the clearing of sufficient take-off and landing runs. Imagine a fully-laden Spruce with hundreds of soldiers and a tank onboard. During its take-off run, one of the sponson floats hits some debris that had not been cleared causing the float to fill with water. The normal result for seaplanes was a very nasty accident followed by the aircraft capsizing. How are those hundreds of soldiers going to escape and what would happen to the tank that was being ferried. The entire concept was such a leap over then-current experience that it was a disaster (or several disasters) waiting to happen.

My bottom line remains that, despite its grace and the sheer guts to build such a large seaplane, the Spruce never proved anything more than it could hop briefly. To extrapolate that single incident to suggest it could have been operationally viable is a huge stretch and still ignores the challenges of safe operation for the type.

 

[FLYBOYJ]

Hang on a second. The thing got airborne for a few seconds on what may, or may not, have been a high-speed taxi run. How does that possibly equate to evidence it could meet all of its performance requirements? Stall characteristics, handling, trimming for unbalanced loads, maximum speeds - none of these had been remotely examined.

The major portion of the contract said it had to fly. With that said Hughes was relieved of justifying many of the cost over runs associated with the program. All the other characterizes would have come later at the discretion of the customer who choose not to pursue further development, that being the US government.

The "suckiness" i was referring to was in comparison to a conventional land-based aircraft - sorry for my use of non-technical words. However, overcoming hydrodynamic drag is critical and mistakes are made in designs. I agree the design of floatplane hulls was well understood but the hydrodynamic properties of the Spruce were never fully explored. For example, the Bv138 was completely redesigned, including a new planing hull, after early versions lacked performance.

OK, but I can assure you there isn't much more "suckiness" on water than a landplane trying to take off on wet grass. The greatest aerodynamic detractor on floatplanes and in some cases seaplanes are the floats themselves and any struts needed to support them.

The safe operation of the Spruce would have presented massive challenges, not least the clearing of sufficient take-off and landing runs. Imagine a fully-laden Spruce with hundreds of soldiers and a tank onboard. During its take-off run, one of the sponson floats hits some debris that had not been cleared causing the float to fill with water. The normal result for seaplanes was a very nasty accident followed by the aircraft capsizing. How are those hundreds of soldiers going to escape and what would happen to the tank that was being ferried. The entire concept was such a leap over then-current experience that it was a disaster (or several disasters) waiting to happen.

While you have valid points to risks that may have been encountered during operation, the same could be said for runway FOD hazards during the operation of large land based aircraft. The fact remains that flying boat operation at that time really did not produce a lot of accidents when operated in a cargo role. Look at the record of the Mars.

My bottom line remains that, despite its grace and the sheer guts to build such a large seaplane, the Spruce never proved anything more than it could hop briefly. To extrapolate that single incident to suggest it could have been operationally viable is a huge stretch and still ignores the challenges of safe operation for the type.

I disagree - as stated Hughes knew EXACTLY what he was doing and just the fact that it lifted into the air gave engineering viability to the concept of a huge transport aircraft moving large amounts of personnel and cargo over long distances. The fact that this aircraft was a flying boat did involk more operational risk, but the concept was proven and its amazing how the nose of the aircraft looked like the C-5!

 

[davparlr]

Hang on a second. The thing got airborne for a few seconds on what may, or may not, have been a high-speed taxi run. How does that possibly equate to evidence it could meet all of its performance requirements? Stall characteristics, handling, trimming for unbalanced loads, maximum speeds - none of these had been remotely examined.

Nor does it equate to them not being met.

The safe operation of the Spruce would have presented massive challenges, not least the clearing of sufficient take-off and landing runs.

No more so in takeoff length than the aircraft I listed for comparison, maybe a bit wider.

Imagine a fully-laden Spruce with hundreds of soldiers and a tank onboard. During its take-off run, one of the sponson floats hits some debris that had not been cleared causing the float to fill with water. The normal result for seaplanes was a very nasty accident followed by the aircraft capsizing.

or imagine a A380, loaded down, striking debris on the runway causing catastrophic loss of the landing gear and/or engine/fuel system. Or an catastrophic engine loss puncturing a fuel tank over the Pacific.

My bottom line remains that, despite its grace and the sheer guts to build such a large seaplane, the Spruce never proved anything more than it could hop briefly. To extrapolate that single incident to suggest it could have been operationally viable is a huge stretch and still ignores the challenges of safe operation for the type.

My bottom line is that, at the time of its cancellation, the H-4 never did anything to show that it could not perform as designed nor was their any excess risk compared to contemporary designs including the B-36 and other large seaplanes like the Martin Mars. Size does matter and that does affect unknowns. Also, more engines increase failure rates and must be understood, but, all in all, I don't see a prediction of an accident waiting to happen after normal engineering development.

 

[buffnut453]

While you have valid points to risks that may have been encountered during operation, the same could be said for runway FOD hazards during the operation of large land based aircraft.

But once you've done a FOD-plod, by and large a runway will stay clear if it's not used. The same cannot be said of the sea. Look at the amount of detritus that gets washed up at every tide - trash, hunks of wood, etc. What's being discussed here is the use of a very large aircraft in a regular, frequent resupply operation and the Mars was never used for that, nor was it used for carrying hundreds of soldiers.

 

[buffnut453]

or imagine a A380, loaded down, striking debris on the runway causing catastrophic loss of the landing gear and/or engine/fuel system. Or an catastrophic engine loss puncturing a fuel tank over the Pacific.

I'm afraid comparing the the reliability and emergency systems of Spruce with those of the A380 is not a credible argument. The A380 has benefitted from years of experience with escape slides, smoke hoods for passengers, multiple-redundancy of systemsetc etc that the Spruce never would have possessed. Also, in wartime, civilian flying constraints were thrown out - how many DC-3s were flown in overloaded conditions because the situation demanded it. As for the Spruce's take-off run, we are simply left with the calculations because it was never proven. None of the aircraft's performance was ever proven except that it could take off, fly briefly and then land again in a very lightweight configuration.

I guess we'll have to agree to disagree!

 

[FLYBOYJ]

But once you've done a FOD-plod, by and large a runway will stay clear if it's not used. The same cannot be said of the sea. Look at the amount of detritus that gets washed up at every tide - trash, hunks of wood, etc. What's being discussed here is the use of a very large aircraft in a regular, frequent resupply operation and the Mars was never used for that, nor was it used for carrying hundreds of soldiers.

Again, a "possible" risk that "could have" or "could not have" been encountered. As much debris as there is in the ocean, it is still very vast and I don't see this as an issue unless you have a very large item in the ocean directly in front of the hull or pontoon. Again, a "what if" that could have been probably mitigated.

As far as the Mars - 5 of them were used regularly between the US mainland and Hawaii and were retired in 1956. One of them burnt up as the result of an engine fire. They operated for 9 years with little or no problems and hauled hundreds of tons of cargo during the period. They also carried up to 105 passengers, probably not in comfort, but not a small amount by any means. Not the size of the Spruce Goose, I think this shows that a large flying boat was able to be operated on a regular basis.

 

[Messy1]

"The thing got airborne for a few seconds on what may, or may not, have been a high-speed taxi run"

I would argue that if the H4 did get airborne by "accident on a high speed taxi run" as you call it, imagine what it could do at full take off speed and power. If the liftoff was a accident, perhaps the airframe was even more efficient and capable than you give it credit for, requiring even less power and speed than predicted. I personally believe Hughes planned for the takeoff, or the aircraft would not lifted off 70 feet out of the water, nor for the distance it flew. I believe Hughes planned on flying the H4 to silence his critics who accused him of war profiteering, and to prove to everyone the plane was capable of flight.