Official FMS 1500mm P-47D Razorback Thread

[Grossman56]

I wonder if you couldn't rig up a 'test stand' using a spare motor/ESC and receiver placed in a solid wooden box or something similar. Seems to me that might be a be a better route than risking the airplane each time. Just a thought.
How did the prop balance work out after the cuffs were on?
I'll be heading to the field tomorrow hopefully around 8:30 depending on the wind, hopefully see you there.

Grossman56
(Dangerous Dan)

[davegee]

Great test data. If you're like me, many ideas in my sleep will eventually transpire into a workable solution for your Cuff problem. I would guess that the Curtiss engineers went through many designs before they got it right.
Best Regards, Rex

Thanks, Rex. Whenever I have days like this, I try to think of a tour I took once of Thomas Edison's laboratory that was moved to Greenfield Village, Michigan by his good friend Henry Ford many years ago. It looks as if Edison had just stepped out for a few minutes. But as you look around there is a wooden barrel full of broken light bulbs, all failures as he searched again and again for the proper filament to make an incandescent bulb. After literally a barrel full of failures, he finally came up with a winner. It's good to remember people like Edison who kept at it until they succeeded.

Cheers

Davegee

[jetfool]

Great test data. If you're like me, many ideas in my sleep will eventually transpire into a workable solution for your Cuff problem. I would guess that the Curtiss engineers went through many designs before they got it right.
Best Regards, Rex

[davegee]

I took out my P-47 "Ole Cock" for a test flight with the new designs for the prop cuffs, courtesy of Elbee. I did a high power runup on the ground first. I was used to the sound that my V1 cuffs that I have been experimenting with, sort of a vibrating sound, not too bad, but noticeable over when you don't have the cuffs on. I decided to do at least one flight anyway. I don't need full power with this big FMS V3 prop, usually about 75 percent power and it gives a very realistic takeoff and climbout to the real thing. On this first takeoff I heard a "POP!" "POP!" in pretty short order during the takeoff roll. I immediately knew that at least two of the cuffs had popped off under the strain of the spinning motor. I was used to this from previous tests and continued the flight. It was pretty normal and I brought it back in for a landing. Unfortunately, the tail wheel did not come down (even though it has been extremely reliable in the past) and I got some very minor abrasion damage to the bottom of the tail area where it had contacted the runway as it slowed down to a stop. Minor repair, doing that now.

Upon examining the prop, two of the four cuffs had indeed departed the airplane (symmetrically, on opposite sides of the hub) and I found the remains of them on the runway. They had broken on each side where they contacted the leading and trailing edges of the prop. For some reason, the other two cuffs stayed on, not sure why. I used a drop or two of rubbery canopy glue on each cuff and they all seemed secure when I pushed and pulled on them several times while putting them on.

I tried one more flight to see how losing two of the cuffs would affect the airplane in flight. This became a very challenging flight and with the aircraft in a clean configuration it seemed like it was Really left wing heavy out of trim. It was controllable but I brought it down after a few more laps. I'm pretty certain that losing two of those cuffs caused this unusual flight characteristic and it was a bit of a challenge to get it safely on the ground. But that I did, made a normal landing to a safe stop.

What to take from this experience? I think first, I'll go back to the standard propeller configuruation using the V3 props. I never have any problems with those. Second, I can still use the beautiful Elbee Curtiss Electric prop dome that looks so great. It had nothing to do with the flight performance in a negative way at all.

I am going to print up two more of the Elbee cuffs and put back on that prop to use as a static model for now. When I fly though, I'll put the non-cuffed prop on for better performance.

I think the best solution would be to make a prop from a mold that has the prop cuffs altready molded into the parts, like what the E Flite 1.5m P-51D has on its props. That would probably be expensive to do, and I probably won't go that route.

The FMS 1.6m P-47D razorback is still one of my favorite foamie warbirds to fly. This has been an interesting experiment, and I'm still glad I undertook doing it. The cuffs really add some realism to the propeller to make it look like the Curtiss Electric props used back then. Perhaps there is some design refinement that can be done to match why two of the four cuffs stayed on while the others didn't. Hmmm...

Happy Fathers' Day to all who are fathers out there!

Cheers

davegee

[davegee]

Davegee,
I am Very LUCKY to have friends like you and Elbee. My excitement has accelerated since my early scale foam aircraft. You both are unselfish about sharing your ideas.
Best Regards, Rex

Hi Rex: I'm assuming you have or will have the V3 FMS Corsair 1700mm prop for this. If so, all you have to do is paint the cuffs flat black, and slide then in place with a bit of rubbery glue like canopy glue or something so you can get them off if you need to change props due to damage or whatever.

Let me confirm that these cuffs will work and not come apart under the stresses of flight first. I'll report back after my tests are completed. I might be able to do this tomorrow (Sunday) or Monday.

Cheers

Davegee

[jetfool]

Davegee,
I am Very LUCKY to have friends like you and Elbee. My excitement has accelerated since my early scale foam aircraft. You both are unselfish about sharing your ideas.
Best Regards, Rex

[davegee]

davegee

Looking forward to your flight test results.

Got my fingers, toes, eyes, and tees crossed.

Best, LB

Without flight testing it yet, I would say you hit it out of the park again! Hopefully they won't pop off like my earlier attempts did. I really like your design and expect that it will "fly" through the tests in great shape next week!

Thanks again for doing this! If these work ok, I can send some to Rex to put on his Lucky! P-47.

[davegee]

Dave what was the thought process. For these cuffs on the full scale ,, they do look 😎

Hi Craig: the size was fairly close with previous attempts I made, but these are closer to the exact size. My original vinyl ones were just pieces of black vinyl or thin plastic folded over on itself and glued at the seam where they came together. They slid on the prop ok but had to be glued onto the prop to stay on. They were open at both ends. Because of that, I think air loads in flight would run through those open areas and popped the cuffs off now and then. Nonetheless, when that happened, there was NO decrement to the flying characteristics of the airplane. They did make a fairly loud "POP!" that sounded pretty cool, though!

Elbee came up wth a 3D printed cuff design that is closed off on the end closest to the prop base but there is a hole in it that allows passage of the prop shaft to go through it to then screw into the prop hub. I'm thinking that rotational forces will want to push the prop cuff out towards the end of the propeller and depart the airplane, but this prop cuff is very strong for its weight and I am fairly confident that they will withstand those pressures and remain in place on the prop . The "acid test" of course will be ground full power testing, and flight testing that I hope to do early next week. I'll report back how it goes. Elbee's design is excellent and follows the shape of the prop like a hand in glove. I made a minor change to the design to enlarge it slightly to help the cuffs slide onto the prop shafts better, but that done, it works great!

Cheers

davegee

[Elbee]

davegee

Looking forward to your flight test results.

Got my fingers, toes, eyes, and tees crossed.

Best, LB

[f4u ausie]

Dave what was the thought process. For these cuffs on the full scale ,, they do look 😎

[davegee]

I just finished a new mod for my Curtiss Electric propeller that has cuffs on it. Actually, it's just a scale cuff addition to the standard FMS V3 Corsair 1700mm prop. but it should be fairly close to the real thing without making a mold for a totally new prop with the attached cuffs.

Anyway, a HUGE debt of thanks to Elbee for coming up with the scale 3D printed Curtiss Electric prop dome, as well as an improved 3D printed cuff design that easily slides through the prop shaft at the bottom of the prop and tacks into place for good keeping with a flexible glue like Canopy glue. I don't think there is any way these will come off in flight like my original vinyl ones I did before. Those lasted for a while, but sooner or later the stress of flight popped them off so I had to go with a new direction for scale props.

I should be able to flight test these on my FMS P-47 "Ole Cock" next week to confirm that they are solid and won't pop off somehow like my first generations ones did.

Here's a few pics. I should have better ones out at the field next week.

Cheers

Davegee

[davegee]

Great pics there Dave as always been almost zero c. Mornings here Looks like sat Arvo will be my fly day hopefully we will see

Wow! For "down unduh" that sounds pretty cold! Hope it warms up some so you can fly without wearing a down coat and fur hat!! (lol)

Nice hearing from you again. I'm going to fly tomorrow morning, too, as we are in for a string of nice flying days. Have to strike while the iron is hot, as they say. I think tomorrow I'll be flying my Spitfire and F9F-8 Cougar. The Cougar is becoming one of my favorite jets to fly. My Spittie is over 8 years old, my oldest surviving rc plane.

Cheers

Davegee

[f4u ausie]

Great pics there Dave as always been almost zero c. Mornings here Looks like sat Arvo will be my fly day hopefully we will see

[davegee]

It has been a fabulous week to fly mornings in Cody, WY! Today, I took out my FMS "I Wanted Wings" P-47D and EFlite P-51D LOU IV/Athelene up for some fliights. I'll also attach some period photos taken almost exactly 81 years ago of them flying in England with the 8th USAAF. Sadly, both of these aircraft met their tragic ends not long after the photos were taken. Looks good for more flying tomorrow morning. Happy flying, wherever you are!

Davegee

[davegee]

Davegee,
Looks fantastic. I am sorry to report that the HS girl that was designing the Cuffs and wheel told the teacher her files were deleted and she can't send them to me. I think maybe she didn't care about others just wanted a good grade. I will send her wheel and the cuffs but the cuffs are not even close to what we need. She did add about .020-.030" thickness to the outer flange of the wheel and I think it will hold your tire well. I asked for a 2-piece cuff with the inner sections profiled to the prop to fit around this and glued. Didn't happen! Time to seriously consider my Prusa and remember my Auto-Cad 1 skills. I'm sure the Auto-Cad has leaped ahead since I used it.
Best Regards, Rex

Hi Rex: no problem. I was thinking I might need to make this a "dual track" project, just in case the high school girl was not able to come up with what we asked her to do. I have my local friend who works at the Ace Hardware working on it for the past few weeks. I think he is on track to give me a test object that I can try on my two P-51s to see if that corrects the problems with the wheels and tires and groundloops. He told me he'll have a print in a week or so. I lfew my Hun Hunter today without problems, even though the outer wheel on one is breaking where it normally does using the Robart tires. Hopefully, this will be the fix for it.

Elbee has a few ideas on the cuffs and my Ace Hardware friend has come up with a promising prototype for a print using a different filament that is somewhat flexible. That one might be a winner, too.

In any event, I really appreciate all your efforts to try and get these parts redesigned and tested for these airplanes. In the end, everything will work out fine. I hope the HS kids got something out of designing projects like what we challenged them with, and will use that knowledge to be better in whatever field they go into someday.

Best,

Dave

[jetfool]

Davegee,
Looks fantastic. I am sorry to report that the HS girl that was designing the Cuffs and wheel told the teacher her files were deleted and she can't send them to me. I think maybe she didn't care about others just wanted a good grade. I will send her wheel and the cuffs but the cuffs are not even close to what we need. She did add about .020-.030" thickness to the outer flange of the wheel and I think it will hold your tire well. I asked for a 2-piece cuff with the inner sections profiled to the prop to fit around this and glued. Didn't happen! Time to seriously consider my Prusa and remember my Auto-Cad 1 skills. I'm sure the Auto-Cad has leaped ahead since I used it.
Best Regards, Rex

[davegee]

davegee

WOW and WOW!!

CE Prop Hub looks outstanding, Dave.

Ya dun good.

Best, LB

Thanks, your design was great. And flight tests went perfectly for this item, no issues whatsoever.

Davegee

[davegee]

davegee

Dave,

Is the 4-bladed prop you're using the FMS 1700mm Corsair D 4-blade?

Just asking as I have one, as well, and might look at your prop cuff as a new project.

Curiously, LB

Hi Steve: yes, I am using the standard V3 FMS Corsair 1700mm prop as a test bed, and then sliding the prop cuffs onto the base of the prop. A lot of the ones that I made up of thin vinyl folded in half and glued at the seam worked for some time, but sometimes they would depart the aircraft with a fairly loud "POP!" as they fell off the plane. But no matter what happened with these in flight, they had no effect on the aircraft's perfomance if one or more fell off in flight, which is good. I had thought of a two part cuff that would have a front and back and then glued onto the prop which might have worked better, but the guy I was working with who lived in Philadelphia on some projects decided to not do any future projects like this, for whatever reason a few years ago.

Although not a perfect solution to making a scale CE prop, this was an inexpensive way to go that at least looked fairly realistic and accurate to the real aircraft. Most of the P-47s built used this CE prop, more than the Hamilton Standard props.

I would be interested in any ideas you might have on this. If it is something I can print up and test, that would be good, along with my friend doing similar work at Ace Hardware. I'm sure a good solution can be found for this.

Best,

Davegee

[Elbee]

davegee

Dave,

Is the 4-bladed prop you're using the FMS 1700mm Corsair D 4-blade?

Just asking as I have one, as well, and might look at your prop cuff as a new project.

Curiously, LB

[Elbee]

davegee

WOW and WOW!!

CE Prop Hub looks outstanding, Dave.

Ya dun good.

Best, LB