Roost Air Lounge => The Classroom => Topic started by: Frank N. O. on January 24, 2010, 04:17:41 PM
Title: Could the Spruce Goose climb out of ground-effect?
Post by: Frank N. O. on January 24, 2010, 04:17:41 PM
Now the Hughes H-4 (or is it HK-1?) Hercules as it's officially called was to my knowledge only ever flown once and only for a very short distance and at low altitude, but has anyone recently tried to make either a scale-model test or computer simulation to see if the design could've worked?
Frank
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Oddball on January 24, 2010, 04:41:29 PM
Have seen photos a Radio Controlled version of the "Spruce Goose" flying on electirc motors.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Frank N. O. on January 24, 2010, 05:02:51 PM
Any idea if that was made to be comparable to the real thing? A radio-controlled model of Baloo's Sea Duck was also made but that had a much wider wing-span than drawings showed and when I asked about the Sea Duck and showed the drawings here a while ago it was said that the wings were really small so it would've had to have a lot of engine-power to fly as a real full-size plane. Here's the RC model btw: http://freenet-homepage.de/punikaoase/page106349961f3.html
Frank
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: 4X-NTY on January 24, 2010, 05:56:33 PM
As much as I know,RC planes shouldn't be any help in figuring this out,they're engine is relatively stronger,the fly relatively faster and relatively lighter than the real things,so even if the model is exactly in the shape of the real thing but smaller,it wouldn't fly the same as the real thing.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Louis on January 26, 2010, 05:42:46 AM
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Frank N. O. on January 26, 2010, 01:17:30 PM
Good points 4X, I hadn't really thought about that before I posted, far from everything in the world can just be scaled up and down and still work the same, just look at insect-legs compared to hippos or elephants.
An X-Plane model could be interesting if it's made authentically considering X-Plane's actual aerodynamic simulation, thanks for the link :)
I remember seeing that someone not long ago made a full-size replica of a concept-plane designed many decades ago by a famous aerodynamic engineer. It was never tested when it was made, I think it was due to WWII starting, so the concept behind it was never confirmed. It was basically a big bagger with a propeller inside and wings attached and a cockpit on top of the barrell. I think that they did actually get the replica to fly and thus confirmed the theory. I was just wondering if someone had gone back and tested the Spruce Goose, of course not with a full-size replica but a computer-simulation.
Frank
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: 4X-NTY on January 26, 2010, 03:06:33 PM
As for the X-Plane model,I think that i tested it and it flew... I'll check it again!
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Ragwing on February 13, 2010, 02:47:56 PM
During the first and only flight, the tail was twisting and wagging. The crew were not sure that the aircraft would stay whole.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Frank N. O. on February 15, 2010, 04:48:11 PM
Ah, that was the other thing I'd been thinking about, if the frame was strong enough.
Frank
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 15, 2010, 10:38:54 PM
I have aerospace physics book here, I'll bring it to work with me tonight and see if I can figure out some numbers that will shed some light on this.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 16, 2010, 08:09:47 AM
So after a bit of searching I found the formulas we'll need to figure this out. However now comes the hard part. To do this, we need the chord, chamber, wing surface area, AOA, and a bunch of other specifications for the H4. I did a bit of searching and found some but am missing pretty much all the important ones. Ideas?
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Oddball on February 16, 2010, 11:19:21 AM
Will this help: http://fennerschool-associated.anu.edu.au/fpt/nwfp/goose/goose.html DIMENSIONS Wingspan 320 ft 96.9 m
Tailspan 113.5 ft 34.4 m
Vertical Tailspan 49.5 ft 15 m
Hull Length 219 ft 66.4 m
Hull Width 25 ft 7.6 m
Hull Height 30 ft 9.1 m
Overall Height 79 ft 24 m
Gross Weight 300,000 lbs 136 200 kg
Wing Area 11,430 sq. ft. 1050 sq. m
Max. Wing Thickness 11.5 ft 3.5 m
Payload 130,000 lbs 59 020 kg
Fuel Capacity 14,000 gallons 56 000 L
Power 24,000 hp
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 16, 2010, 04:47:40 PM
That a good start. Key ones are going to be chamber, chord, and angle of attack of the wing.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Oddball on February 16, 2010, 05:11:03 PM
What gets me is that now that Howard Hughes is dead and buried surely his last wish for the HK1 never to fly again is invalid so Evergreen should try and fly her ;D
found the NCA numbers for the wing: Roots NACA 63(420)-321, �Tips NACA 65(420)-415
having trouble finding the AoA though :-\
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Baradium on February 16, 2010, 06:33:20 PM
What gets me is that now that Howard Hughes is dead and buried surely his last wish for the HK1 never to fly again is invalid so Evergreen should try and fly her ;D
found the NCA numbers for the wing: Roots NACA 63(420)-321, �Tips NACA 65(420)-415
having trouble finding the AoA though :-\
AOA changes in flight, you thinking AOI?
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 16, 2010, 06:49:42 PM
Correct AOI, been awhile since I messed with this physics stuff.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Baradium on February 16, 2010, 06:55:46 PM
Honestly, I never had any doubts about whether it could fly. The whole reason people asked about it when it was built was because of the sheer size of it in relation to anything else flying at the time.
Speaking of large airplanes, I got to see the AN-225 last week. Just wish I could've gotten a look inside.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 16, 2010, 07:07:16 PM
Honestly, I never had any doubts about whether it could fly. The whole reason people asked about it when it was built was because of the sheer size of it in relation to anything else flying at the time.
Speaking of large airplanes, I got to see the AN-225 last week. Just wish I could've gotten a look inside.
So not fair!
I saw the 787 land last Saturday at BFI. Just by dumb luck I was there when ZA002 touched down.
In the wiki article it says that the service ceiling of H4 is around FL200. I dont see why it wouldn't get there.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Baradium on February 16, 2010, 07:09:39 PM
Honestly, I never had any doubts about whether it could fly. The whole reason people asked about it when it was built was because of the sheer size of it in relation to anything else flying at the time.
Speaking of large airplanes, I got to see the AN-225 last week. Just wish I could've gotten a look inside.
So not fair!
I saw the 787 land last Saturday at BFI. Just by dumb luck I was there when ZA002 touched down.
In the wiki article it says that the service ceiling of H4 is around FL200. I dont see why it wouldn't get there.
It was dumb luck for me too. I was sitting down enjoying some good sourdough pancakes when my friend said he'd read that the world's largest airplane was going to be in fairbanks for 12 hours refueling and getting ready to continue on it's way from Japan to Haiti hauling heavy equipment.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 16, 2010, 07:20:07 PM
http://en.wikipedia.org/wiki/NACA_airfoil
So there is the wiki article about NACA airfoils. For the life of me, I cant figure out which series those NACA numbers are. It seems as if we can figure that out, we should be able to then get the lift/drag ratios and prove it could fly. Thou the more I read about the topic online, it seems that most everyone is in agreement that it is able to fly out of ground effect.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: undatc on February 16, 2010, 07:21:06 PM
Honestly, I never had any doubts about whether it could fly. The whole reason people asked about it when it was built was because of the sheer size of it in relation to anything else flying at the time.
Speaking of large airplanes, I got to see the AN-225 last week. Just wish I could've gotten a look inside.
So not fair!
I saw the 787 land last Saturday at BFI. Just by dumb luck I was there when ZA002 touched down.
In the wiki article it says that the service ceiling of H4 is around FL200. I dont see why it wouldn't get there.
It was dumb luck for me too. I was sitting down enjoying some good sourdough pancakes when my friend said he'd read that the world's largest airplane was going to be in fairbanks for 12 hours refueling and getting ready to continue on it's way from Japan to Haiti hauling heavy equipment.
Nice, you were in Bethel right for awhile? I was watching dirty jobs last week, and he was up there doing something with geese. Probably shouldn't go much further than that ::sick::
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Baradium on February 16, 2010, 07:25:42 PM
Nice, you were in Bethel right for awhile? I was watching dirty jobs last week, and he was up there doing something with geese. Probably shouldn't go much further than that ::sick::
No, I avoided being based in bethel like the plague. I flew through it a number of times, but I was one of the lucky ones that got to go back to town because it was always an out and back...
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Jupiter on October 29, 2010, 11:18:51 AM
HAs anyone already been messing with these calculations? otherwise I might give it a try this weekend... As for the remark on model airplanes being able to fly proving the real thing could fly: If you scale things, you change their aerodynamics. This because Mach and Reynolds numbers of the airfoil and their ratio change with scaling, resulting in different aerodynamic behavior...
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Ragwing on October 30, 2010, 02:11:12 PM
If you scale things, you change their aerodynamics. This because Mach and Reynolds numbers of the airfoil and their ratio change with scaling, resulting in different aerodynamic behavior...
Not only is the Spruce Goose made of wood (They did not use spruce), they did use screws to hold the wood together until the glue dried. Then the screws were removed.
Howard Hughs had to make the Spruce Goose fly to received the government payments. Just in case it crashed or broke apart, Howard had the pontoons and the body were filled with inflated beach balls. Then he could put it together and try again. RW
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Oddball on October 30, 2010, 06:32:56 PM
I wonder if they would ever try again to fly it.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Jupiter on October 30, 2010, 07:12:03 PM
With some simplifications, it shouldn't be too hard to calculate. Biggest problem will probably be finding a Cd0 for it. After that, a maximum climb rate should be calculatable. If this is around several m/s, it's feasible the aircraft would fly without ground effect. Maximum lift coefficients can be found by entering this profile in software like Javafoil etc. @ Oddball: If they'd even think about flying it again, they'd probably be stopped by both the FAA and their budget. These aircraft cost a fortune to maintain and run (this thing had 8 engines of 71.4 Liters each), and the FAA would probably not like an unproven design take to the skies without an extremely costly full check, and of course a huge pack of paper and computer simulations proving this aircraft should be able to safely take to the skies.... It'd probably be cheaper and easier to build a replica with some modifications, than trying to fly this behemoth again...
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Mike on October 31, 2010, 04:41:05 PM
@ Oddball: If they'd even think about flying it again, they'd probably be stopped by both the FAA and their budget. These aircraft cost a fortune to maintain and run (this thing had 8 engines of 71.4 Liters each), and the FAA would probably not like an unproven design take to the skies without an extremely costly full check, and of course a huge pack of paper and computer simulations proving this aircraft should be able to safely take to the skies.... It'd probably be cheaper and easier to build a replica with some modifications, than trying to fly this behemoth again...
sadly, this very problem keeps a lot of people and companies from developing a new aircraft.... I just saw the History of the helicopter on the Military channel and it wasn't long until Sikorsky and Piaseki ran into issues with the FAA. Had we invented the helicopter now, it would never fly......
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Jupiter on October 31, 2010, 08:00:38 PM
hehe, true, but there is hope though. Things like the Terrafugia Transition etc do call for some new rules and revising of regulations... Also, generally you can certify replicas of old aircraft on the basis of "it was OK then, so it is OK now" (at least, that's how we did it with ours...). The problem is that this aircraft was never fully certified, or even flown multiple times...
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Jupiter on November 01, 2010, 03:40:07 PM
Ok, bear with me: (scroll down for conclusion)
Steady rate of climb (ideal climb situation, real values lie about 25-35% lower) is defined as the power available minus the power required, divided by the aircraft weight.
(Pavailable- Prequired) / W
Available power Pa is known, 8 Wasp Major engines of 2640 [kW] each, results in total available power of 21.12 [MW]. If you assume a propellor efficiency of around 75%, this results in around 15.8 [MW] of power available. The weight W can be guesstimated: assuming an MTOW of 180000 [kg], this is 180000 * 9.81 = 1.77 [MN]
Required power Prequired is not known here, but is defined as the drag force D multiplied by the airspeed V. Both of these values are also not directly known, but can be deduced with some assumptions. As wikipedia quotes a cruise speed of around 408 [km/h] or ~ 113 [m/s], a reasonable assumption of climbing velocity seems somewhere around 75 [m/s].
The drag D can be calculated by the probably familiar formula D = CD * 0.5 * rho * V2 * S. The air density rho can be taken at sea level to be 1.225 [kg/m3], the velocity V was calculated above and the wing surface area S is known to be 1050 [m2]. Now only the drag coefficient CD is unknown. CD is defined as CD0 + (CL2 / (pi * A * e) ). The Aspect ratio A is defined as wing area divided by the square of the span, or 1050 / 96.9 = 10.8 [ ]. Oswald factor e is assumed 0.6 [ ], since it's not easily calculated and a relatively old design. 0-lift drag coefficient CD0 is assumed to be 0.025 [ ], a rather reasonable value since the aircraft has huge extrenal features like floats... Lastly, the lift coefficient CL needs to be found, which can be done by entering the airfoil data in JAVAFOIL. I plotted the mentioned airfoil, but seeing the shape, I'm having a hard time believing this is what was used. The program gave me a maximum lift coefficient of 1.8, which is rather high, so a more reasonable value of 1.1 [ ] will be assumed. This gives a drag force D of (0.025 + (1.12 / (pi * 10.8 * 0.6) ) ) * 0.5 * 1.225 * 752 * 1050 = 305 [kN]. Therefore, the power required Prequired will be 305 * 103 * 75 = 22.9 [MW]
This is larger than the power available, so the rate of climb will not be positive. This means the aircraft would not be able to climb, so certainly wouldn't be able to fly. What's bothering me is that this difference seems a little too large for my taste. Since I did make a lot of assumptions here, it could very well be there are some mistakes there...
If you spot any errors or have any theories on why this answer's resulting from this calculation, or have some better values for some of my assumptions, please let me know!
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Franz on November 01, 2010, 06:51:28 PM
I'd say you'll have to calculate the speed it could actually achieve by v max = (Pavailable/D)1/3, because it can only accelerate as long Pavailable > Prequired. Using your figures I get v max ~ 66 m/s, assuming it has no drag from still being in the water. The next step I think should be to figure out how much lift is generated at that speed [I'll see if I can figure out that JavaFoil-thingy] and see if it's enough to get it of the ground. Also, I would assume the weight to be something to between 150000kg (MTOW - one Sherman tank) and 90000kg (MTOW - 750 troops) because I think the using the projected payload is a little ambitious for a first prototype.
Now tear it apart while I go back to (not) studying physics . . .
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Jupiter on November 01, 2010, 10:03:11 PM
I'd say you'll have to calculate the speed it could actually achieve by v max = (Pavailable/D)1/3, because it can only accelerate as long Pavailable > Prequired. Using your figures I get v max ~ 66 m/s, assuming it has no drag from still being in the water. The next step I think should be to figure out how much lift is generated at that speed [I'll see if I can figure out that JavaFoil-thingy] and see if it's enough to get it of the ground. Also, I would assume the weight to be something to between 150000kg (MTOW - one Sherman tank) and 90000kg (MTOW - 750 troops) because I think the using the projected payload is a little ambitious for a first prototype.
Now tear it apart while I go back to (not) studying physics . . .
You've got good points here! Too tired to redo the calculations now, but I'll probably do some revising the day after tomorrow. Since the velocity to the third power determines the required power, small differences in this could make a large difference. Also, I've been searching for the power these engines deliver, and it could be it's about 250W/engine more than I used here. About the weight: it's not yet used in this calculation, since it's only used for determining climb rate, not power required.
Title: Re: Could the Spruce Goose climb out of ground-effect?
Post by: Oddball on November 01, 2010, 11:29:47 PM
8× Pratt & Whitney R-4360 Wasp Major radial engines, 4,000 hp (2,640 kW) each driving 4 bladed standard Hamilton props
