Why no spinners?
- Thread starter riacrato
- Start date
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Jerry W. Loper
Airman 1st Class
- 121
- Oct 2, 2007
Good question. I'd think that the spinners would be added if they gave the plane another 10 or 20 m.p.h. speed.
Might have screwed with the airflow. Those later engined aircraft of WW2, especially the second gen stuff, had all sorts of problems with Air Flow to the back set of cylinders. Seems it was the biggest problem with them.
Still a problem today. Have IO-540 (I think that's the number, it's a continental) and the two cylinders up against the back wall are always running hotter than the front ones. And that engine is air cooled too (with nowhere near the HP, around 310).
Still a problem today. Have IO-540 (I think that's the number, it's a continental) and the two cylinders up against the back wall are always running hotter than the front ones. And that engine is air cooled too (with nowhere near the HP, around 310).
Aaron Brooks Wolters
Brigadier General
I'm with you Tim. I think they were trying to get all the airflow they could get into the opening to cool the engine. I could be wrong though.
davparlr
Senior Master Sergeant
The only production radial aircraft in WWII that I could find with a spinner were two, the Brewster Buffalo and the P-61. Several experimental and pre-production planes had one. Since all liquid cooled aircraft had spinners, they must have been an aerodynamic advantage so I would guess it was for cooling. It is noted that the one of the fastest radials in the war, the P-47M did not have a spinner. The experimental, and faster, XP-47J had one. The XP-47J had other aerodynamic clean-ups, so a direct comparison cannot be made.
FLYBOYJ
"THE GREAT GAZOO"
All the above were correct answers. Aerodynamics, cooling, lack there of were all reasons why we seen spinners appear and disappear from some WW2 aircraft. Additionally maintainers may have left off the spinners because of an addition maintenance process that brought no value added to the aircraft's performance. Take a good look at some aircraft spinners and see how many screws hold them on. It's very time consuming removing and installing spinners.
Another point is when they get damaged, they set up some pretty undesirable vibrations and technically you really can't repair a prop spinner as any repair to a spinner will upset its natural dynamic balance designed into it.
Another point is when they get damaged, they set up some pretty undesirable vibrations and technically you really can't repair a prop spinner as any repair to a spinner will upset its natural dynamic balance designed into it.
Bit of reading here, though might be speculative, about the spinners causing over-heating problems.
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Matt308
Glock Perfection
Inhibit airflow to the radial cylinders while taxiing/idle.
Shortround6
Major General
In some cases it was the opposite. the area around the hub and roots of the blades was a low pressure area and on some aircraft the air was going in the cowling by the edge and flowing back out near the hub without going through the cooling fins of the engine.
some planes were fitted with blade root cuffs to help solve this problem, others with spinners and a few with flat disks (or nearly so) mounted to the front of the engine.
See: http://yolo.net/~jeaton/fsmforum/307/001307.jpg
billswagger
Airman 1st Class
- 256
- Mar 12, 2009
My guess is that the larger engines utilized by the USAAF required a sufficient amount of cooling, particularly in climbs.
Considering that the top speeds of these planes were already higher than their contemporaries, it may have been a design niche to help preserve engine heat for performance in climb. The cuffs later fitted to props were said to also improve cooling with out consequence to performance.
Id say definitely an air flow issue.
Bill
Considering that the top speeds of these planes were already higher than their contemporaries, it may have been a design niche to help preserve engine heat for performance in climb. The cuffs later fitted to props were said to also improve cooling with out consequence to performance.
Id say definitely an air flow issue.
Bill
That is a really good point that I forgot about. Thinking more so the prop than the actual spinner but they're part of the same system. But when your prop gets out of balance, it's annoying (possible fatal in some circumstances but it rarely gets to that point). Had it happen once with wood warping. One blade was ok, the other wasn't.
It was a drag (pun intended).
- Thread starter
- #12
Interesting points, thank you.
Cooling and aerodynamics, or the trade-off between were probably the obvious answers. It's interesing how many non-US designs with the R-1830 seem to have a spinner (Saab 17 / 18, LeO 451, MB.176), whereas the US ones don't (but also the Fokker, for example).
If I look at the R-1830 I also notice the era of the engine block (?) where the propeller connects to the drive shaft is round in shape probably to direct airflow to the cylinders.
A spinner in front of that shape might mess with the airflow concept?
Cooling and aerodynamics, or the trade-off between were probably the obvious answers. It's interesing how many non-US designs with the R-1830 seem to have a spinner (Saab 17 / 18, LeO 451, MB.176), whereas the US ones don't (but also the Fokker, for example).
If I look at the R-1830 I also notice the era of the engine block (?) where the propeller connects to the drive shaft is round in shape probably to direct airflow to the cylinders.
A spinner in front of that shape might mess with the airflow concept?
FLYBOYJ
"THE GREAT GAZOO"
Actually that is not the engine block but the propeller gear box and although takes a rounded shape really has nothing to do with airflow. What IS controlling airflow and cooling are those black baffles behind the cylinders.
There were more US types, such as: Douglas SBD-1 to -3, Curtiss SB2C-1, -4, and Lockheed C-69. The Helldiver case is of particular interest here, because on SB2C-3 and -5 variants spinners were omitted.
Airframes
Benevolens Magister
They were also on the early B26 'Marauder', and omitted on later production, I believe due to restricted airflow, and engine over heating.
verner
Airman 1st Class
Possibly metal was at a premium. Everything else was.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Both the Fw190 and the La-7 had fairly large spinners...
Spinners could be damaged during maintenance and handling, and weren't worth the extra care and work. Also some engines needed the cooling effect of the airflow over the gearbox, that was covered up by the spinner. They also interfere with a quick visual damage inspection, hiding small oil leaks, etc.
Dilbert
Recruit
Interesting question. I flew both T-28's and Grumman S-2 Trackers in the Navy with the Wright R-1820 (the S-2 had two) and they didn't have spinners. I went on to fly the Lockheed P-2 Neptune with Wright R-3650's which were, essentially, two 1820's joined to make 18 cylinders, and it had spinners. Cooling was never a concern especially in any of the above. The P-2 used a later version of the Wright engine that had been used on the B-29's and they had no spinners.
I flew quite a bit in both Florida and Texas in training, both hot and humid, and then we used to do a lot of landing practice in the California desert when I was stationed in San Diego (we did our practices at El Centro and Yuma) and the desert runways were very hot (I remember the tower advising us one day the runway temp was 120 degrees). We never had problems with overheating even with spinners.
No clue as to why some did and some didn't. Maybe field maintenance was easier without them?
I flew quite a bit in both Florida and Texas in training, both hot and humid, and then we used to do a lot of landing practice in the California desert when I was stationed in San Diego (we did our practices at El Centro and Yuma) and the desert runways were very hot (I remember the tower advising us one day the runway temp was 120 degrees). We never had problems with overheating even with spinners.
No clue as to why some did and some didn't. Maybe field maintenance was easier without them?
jimh
Senior Airman
Cooling is a big deal for the rear cylinders, particularly for the top jugs that sit behind the prop governor. That said alot of the big piston powered airliners had spinners...any ideas???
Thats not entirely true about the spinner...we had a bird strike this fall...dead center on the spinner. The Yoak's came up from thier shop, they took the spinner home and returned a few days later with perfectly finished spinner. Mark said he thought he saw a bird go by but thought he missed it. The airplane didn't run or fly any different. A new spinner for a 51 will run you about 15-19,000 bucks.
jim harley
Thats not entirely true about the spinner...we had a bird strike this fall...dead center on the spinner. The Yoak's came up from thier shop, they took the spinner home and returned a few days later with perfectly finished spinner. Mark said he thought he saw a bird go by but thought he missed it. The airplane didn't run or fly any different. A new spinner for a 51 will run you about 15-19,000 bucks.
jim harley
