Sea Fury

[peterpont]

Any one out there building or has built the Top flight Sea Fury?
Love these planes --and WHY can you not fly them with the 5 blade prop. So many experienced and innovative flyers here on this wonderful site that I cannot believe that it can't be done.
Also, one of the Submarine Spitfires had a 5 blade prop has well.
Is the a kit out there for that particular plane?
Thanks for any response
Peterpont:)

[cruisemon]

Multi blade props are very inefficient for small engines. The most efficient prop for small engines is a single blade. A 5-bladed prop would probably work, but not perform well.

[Chad Veich]

Peterpont, our small model engines do not have the torque available to swing multi bladed props efficiently. The only reason to go with more blades is to absorb horsepower without excessively long blades. For examply, a full size P-51 would probably perform better with the proper two bladed prop but it would have to be rediculously large to absorb all the ponies and ground clearance would require extremely long gear legs. (which creates all kinds of problems) The only solution on our models is a geardrive to reduce RPM and increase torque. I guess it just hasn't been a high enough priority for most modelers and so very few geardrives have been developed for our applications.

[peterpont]

Thanks for the feedback. Some of the very large models are useing very large Cubic Inch Engines -4 stroke or gas. Why not use a more powerful torque-heavy engine to accomplish this goal of mine?
Electrics are using gearboxs for all sorts of reasons. Would an Electric model with gearbox work out? I have seen 4-Blade props on Electric semi-scale warbirds.


More feedback Please--do not allow this idea to die!

Peterpont

[cruisemon]

As a matter of fact, it would. The model can be built lighter since it does not have to absorb the vibration of an internal combustion engine. There are electric motors that will EASILY handle the weight of the Sea Fury. With a gear reducer that drops the prop speed to maybe 5,000 or 6,000 rpm and a SPECIALLY BUILT PROP with a LOT of pitch and a scale diameter, and Kokam Li-poly cells, it is doable. You will need about a 20" diameter prop with at least a 12" pitch.

Call Jim T. Graham at Hobby-Lobby for more info on the motors and the Li-poly cells. He is among the more knowledgable guys around on electric stuff and Hobby-Lobb has probably the best selection of stuff in the U.S.

[peterpont]

Thanks-Finally-someone who doesn't just assume the 2 blades would fly better--I already knew that. I just want to see the "scales be scales" and with all the attention given to cockpits, retracts, sound and the like, the 2 bladed prop stands out like a "sore thumb' ( Static judging is nice, but pilots know that flying is Better!

More thoughts, ideas, comments and the like. Maybe someone else has had the idea, but let go of it because of the 2 blade comments.---Hell, maybe there is one out there flying ?????????
Peterpont

[ETIGER05]

pete, they aren't "assuming" two bladers would fly better .its an established fact. The reason on these warbirds for multi blades, as has been said before, is to absorb the increase in power of the full size machines. Early Spitfires had a 2 bladed prop(wood &coarse pitch). in order to utilize the increased power on later marks you either use a bigger prop(now the gear has to be longer & LOTS of redesigning of the wing etc.. plus much more easily damaged&heavier.) or you add a blade or two. the engineers at the time had little choice.the prop blades actually interfere with each others air flow to some degree. try flying a model with two blade &then with 3 blade & see which performs better.Ive seen it happen.also our airfoils, being smaller are less efficient so the differences are even greater. sometimes it works out but rarely. also gearboxes usually dont work well on recip engines because the power pulses tear the gears apart. The Radial engine is an exception to this.

[Paul Wilson]

The Centaurus 18 engine in the Sea Fury FB11 was fitted with a two speed single stage supercharger and drove a 5 blade, 3.9 metre diameter propeller which is 153 inches. At 1/7 scale that would mean a 21.5 inch 5 bladed prop. I doubt you could get an electric set up to move that too well. If you use gas then using the idea that for every extra blade you lose an inch in diameter then to get a five bladed 21.5 inch 8 inch pitch prop you would need an engine that could turn a 24.5 inch two bladed prop. The 3w 75i twin spark could do it in theory, it weighs 4.75 pounds without the muffler and would be so big that you would not even get the cowl on never mind cutting it down. The plane would probably end up with a weight of 17 pounds (should be around 11) and would have a wing loading of 46.5 ounces. So basically it would look like rubbish, fly like rubbish if at all but it could be done. The fact is that until we get an inflight continually adjustable pitch prop we will not see it happening successfully for a while. A continually adjustable gearing system could work too but the full scale planes did not achieve ther greater power until the advent of the adjustable pitch props. It is like trying to drive around in a car with no gears.
You will see a lot of people putting multi blade props on warbirds but they are always too small and look ten times worse than the 2 blade as they have such a small diameter. When the plane is flying then the appearance of the 2 blade is fine and approximates at least the diameter.
good Luck
Paul

[peterpont]

Thanks Paul for taking the time to research and outline the painfully obvious.
I have now accepted that without the ability to adjust the prop pitch, there is not a way (that I have knowledge of) to match a 5 blade prop for the Seafury or the Spitefire.
NEXT
Anyone out there care enough about this subject (variable pitch props) to open a thread or respond here?
My thanks again to all who have replied.

[Ken Lapointe]

Its always interesting to find old threads that say won't work well, can't work, don't bother....

And then a few years latter someone shows it can work and work great.

Thunder Tiger Sea Fury with 5-bladed prop!
http://www.rcgroups.com/forums/showthread.php?t=871624&highlight=5+bladed+prop

Thunder Tiger Sea Fury, Lookin Good
http://www.rcgroups.com/forums/showthread.php?t=739347&page=7&highlight=thunder+tiger+sea+fury

[Chad Veich]

Electric propulsion has opened up all kinds of new opportunities for swinging multi blade props. You would not get the same performance from an IC powerplant. Admittedly, Peterpont did not speicify electric or IC in his original post but most assumed he was speaking of IC. Even so, swinging a 5-blader, even with electric, was probably not viable back in 2003 when the question was originally asked. Technology is a wonderful thing!

Its always interesting to find old threads that say won't work well, can't work, don't bother....

And then a few years latter someone shows it can work and work great.

Thunder Tiger Sea Fury with 5-bladed prop!
http://www.rcgroups.com/forums/showthread.php?t=871624&highlight=5+bladed+prop

Thunder Tiger Sea Fury, Lookin Good
http://www.rcgroups.com/forums/showthread.php?t=739347&page=7&highlight=thunder+tiger+sea+fury

[kahloq]

Everyone seems to be forgetting about the MOKI 5 cylinder radial gas 4 strokes. Those motors have a huge amount ot torque and could swing a 5 blade prop. Since the original poster was referring to a seafury.....well...Ive seen quite a few Seafury's with the moki radials. One of my club members has one
I've seen several of these motors in person(mostly the 250cc size) spinning very large multiblade props in seafury's, fw-190's, and a couple corsairs.
Now for size relative to a TF seafury.....maybe the 150cc size would fit.

As far as electric.....a gearbox is not at all needed.
Hobbycity sells some 80mm outrunner motors capable of spinning extremely large diameter and high pitch props. Friend of mine has one of the 80-85-170's and is spinning a 28x12 2 blade on 12s. Easily be able to spin a scale size 21.5x8 5 blade prop or even higher pitch. Those turnigy motors really perform better the higher pitch you go. I have about 10 different sized turnigy outrunners.

[Chad Veich]

Even the mighty Moki will not swing a 5-blade with enough authority to fly the big Sea Fury. The best Brian can do with his is a 3-blade which, IMHO, looks just as bad as a 2-blader on a Sea Fury. The 150 Moki would be a bit of overkill on the little TF Sea Fury! In my opinion the best bet for swinging scale props lies with electric power and I think we will see a great deal more of it in the future. My .02 cents anyway.

Chad