Official FMS 1500mm P-47D Razorback Thread

[davegee]

I just completed a static test of a new prop with the reprinted Elbee V2 improved Curtiss propeller cuffs. This time I used a lot of E6000 flexible glue and later sealed the two ends of the cuff with super glue to help keep them in place and not want to depart the airplane. They look to be on there very solid now. I ran the prop through the wringer, full power for about 30 seconds about 4 times. and then simulated rapid power changes between idle and full power and all in between as might be encountered on a flight.

So, thiis test prop (all parts unpainted until I give them the "thumbs up" after some test flights tomorrow morning) will hopefully pass with flying colors and then I'lll do more test flights with the Elbee final version Curtiss prop dome on the intended airplane "Ole Cock." For tomorrow, I'll be using my oldest surviving P-47, I Wanted Wings.

Will report back after tomorrow's test flights!

cheers

davegee

I was able to get a quick flight in today, although the weather could have been better to do it. Pretty strong crosswind and very gusty and dusty. I had a very minor prop strike on the takeoff roll that I think was caused by a crosswise large crack in the runway surface that caused the front wheels to get stuck momentarily early on the takeoff roll. I decided to take off anyway and it flew ok, although I brought it back down pretty soon to inspect the prop afterwards for possible damage. Just a few scrapes on the prop tips which was easy to sand down to smooth again.

A big difference with this prop is that I sealed the front and rear edges of the Elbee prop cuffs,with CA as well as used a lot of E6000 glue inside the rest of the cuffs to make it pretty solid. When I did a test runup prior to my flight today, I didn't get the same sound that I have been used to hearing before with my old prop cuffs. It was more like everything was humming in unison with no odd sounds or vibrations coming from gaps in the glue joints of my old cuffs that probably caused them to blow off at high rpms of the engine.

I'll continue to fly some more tomorrow with the new prop cuffs. At this point, it looks encouraging. It probably wasn't a problem with the cuffs Elbee made at all, but more probably was my glue joints that caused the problems. If things go well tomorrow, I think this problem is solved! I'll inlcude a pic at the field of the test prop (unpainted.) I am curently painting it and will test it and another prop tomorrow with these cuff improvements.

Davegee

[davegee]

davegee


[ATTACH]n427526[/ATTACH]

Give this a go, Dave.

Same ID as the vase mode print with twice the wall thickness (0.5mm).

I have not printed this but it should be fine.

Do not use vase mode for this as the part is already hollowed except the base.

If it were me, I'd use the same flexible adhesive and spread it all around where the cuff meets the prop.

You might have done that on the previous version, then good.

Best, LB

I just completed a static test of a new prop with the reprinted Elbee V2 improved Curtiss propeller cuffs. This time I used a lot of E6000 flexible glue and later sealed the two ends of the cuff with super glue to help keep them in place and not want to depart the airplane. They look to be on there very solid now. I ran the prop through the wringer, full power for about 30 seconds about 4 times. and then simulated rapid power changes between idle and full power and all in between as might be encountered on a flight.

So, thiis test prop (all parts unpainted until I give them the "thumbs up" after some test flights tomorrow morning) will hopefully pass with flying colors and then I'lll do more test flights with the Elbee final version Curtiss prop dome on the intended airplane "Ole Cock." For tomorrow, I'll be using my oldest surviving P-47, I Wanted Wings.

Will report back after tomorrow's test flights!

cheers

davegee

[davegee]

davegee


[ATTACH]n427526[/ATTACH]

Give this a go, Dave.

Same ID as the vase mode print with twice the wall thickness (0.5mm).

I have not printed this but it should be fine.

Do not use vase mode for this as the part is already hollowed except the base.

If it were me, I'd use the same flexible adhesive and spread it all around where the cuff meets the prop.

You might have done that on the previous version, then good.

Best, LB

Hi Steve: I figure we are 50% on the way to success, since two of the four cuffs stayed on! I think I'm going to start from square one since I have some extra prop blades and hubs and will add your new prop cuffs. I'll run full static tests with these and iif the stay on with that, I'll go for a couple of test flights. Regardless, the shape of even the last ones you made were great, better than I've seen before. We are close, very close, to success!

Thanks again, will post results.

BTW: Danger Dan and I did a photo shoot and he flew his second flight on his new Corsair and mine in the background. He'll post some of the pics we took. Some came out quite well, if I do say so myself. He'll probably post them sometime today.

Cheers

Davegee

[Elbee]

davegee


Curtis Electric Prop Cuff P-47test2.stl

Give this a go, Dave.

Same ID as the vase mode print with twice the wall thickness (0.5mm).

I have not printed this but it should be fine.

Do not use vase mode for this as the part is already hollowed except the base.

If it were me, I'd use the same flexible adhesive and spread it all around where the cuff meets the prop.

You might have done that on the previous version, then good.

Best, LB

[davegee]

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)

Might be a good plan, going forward. I'll work on it. In the meantime, when I want to fly "Ole Cock" I'll just transfer the prop from one of my other jugs (Ham.Stan, prop vs. Curtiss Electric) to fly it around.

I'll try to meet you at the field tomorrow morning. Are you going to bring your Corsair? I'll bring my camera for some in-air shots, whatever you bring.

I think I'll load my Corsair as well as my Cougar.

Davegee

[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