Winter Build 2019-2020: Top Flite P-51 (0.60 size)

OliverW

Legendary member
I could be wrong but I believe that the input and output are what determines how crucial the 2048 vs 1024 debate may be. For example: my Horus gimbals are actually 4096 bit. For those who are unaware of this situation, this means that the extent of the range of movement for one axis of the gimbal is divided up by 4096 steps. This makes control VERY precise. It is a feature that currently only exists on high-end radios like Hitec, Multiplex, and top line models from Futaba and Spektrum. I'll note that some people do not even notice this kind of resolution but if you are a person who does fly precision maneuvers on only ONE airplane, you get so familiar with an airplane that this level of precision really does become noticeable.

This level of high-precision input all becomes an entirely worthless point if you do not have the output to match. Unless you are using some digital servos that extend beyond the average hobby budget, you really will not see much difference. Analog servos are VERY limited to their precision and when you get smaller servos, the problem gets worse because of physical gear tooth engagement. Smaller servos with high precision get very expensive fast because of this limitation and you go to the coreless direct-drive stuff. Essentially you end up with a miniature stepper motor that uses a digital signal.

The point of mentioning all of this is that your initial point about resolution, I think, is not entirely relevant because the signal automatically encodes the precision of the input, transmits it, and then spits it back out. The fact that the SBus converter is simply an additional relay plays in when it simply converts the digital SBus signal to an PWM signal. The interpretation of that PWM signal is done by the servo itself.

So, all of that to say this is a point-to-point system. I will say that I believe that this converter issue may have a filter on the output that does not exist on the other. This filter would limit the range of the signal a bit but the extent of that is TBD. Could I get more travel from endpoint adjustment? Not sure. Would I get the SAME range if I used another protocol? Not sure. It's all speculative so it's best to just accept the KNOWN parts of the system and work with the limitations you have unless you are so inclined to investigate.
100% agree. I'm using 2048 gimbal in my DX9 I believe and I know exactly what you're saying. I flew another person's plane with a top of the line JR transmitter and could feel every difference since I was flying IMAC and precision.
 

SlingShot

Maneuvering With Purpose
Hmmm......so would there be a big difference in feel between 1980 radios and Futabas of today? It seems as though there's a better feel.
 

willsonman

Builder Extraordinare
Mentor
100% agree. I'm using 2048 gimbal in my DX9 I believe and I know exactly what you're saying. I flew another person's plane with a top of the line JR transmitter and could feel every difference since I was flying IMAC and precision.
Yeah, when I moved from my old Taranis to my Horus, it was night and day. Then I started flying IMAC and I could do maneuvers that I had never had enough confidence in control to do before.

Hmmm......so would there be a big difference in feel between 1980 radios and Futabas of today? It seems as though there's a better feel.
Not sure if this is sarcastic but that's like comparing apples and matchbox cars. digital radios were not a thing until the 90s so the "steps" (resolution) did not really exist yet. There is a sense of that if you read up on the evolution of "proportional" radios.

4096 resolution was just coming into its own only 5 years ago. First radios appearing with this level of precision were coming out in the early 2010s. A great example is the move of Hitec from the 1024 bit Aurora 9 to the 4096 bit Aurora 9X in 2012-2013 timeframe. My club has TWO members still using their 9Xs in competitive IMAC to this day. Oh, and it had a touchscreen. Something just now coming to mainstream radios. But all of that radio resolution means nothing on the airplanes until... they spend $75 for ONE servo.
 

OliverW

Legendary member
Yeah, when I moved from my old Taranis to my Horus, it was night and day. Then I started flying IMAC and I could do maneuvers that I had never had enough confidence in control to do before.


Not sure if this is sarcastic but that's like comparing apples and matchbox cars. digital radios were not a thing until the 90s so the "steps" (resolution) did not really exist yet. There is a sense of that if you read up on the evolution of "proportional" radios.

4096 resolution was just coming into its own only 5 years ago. First radios appearing with this level of precision were coming out in the early 2010s. A great example is the move of Hitec from the 1024 bit Aurora 9 to the 4096 bit Aurora 9X in 2012-2013 timeframe. My club has TWO members still using their 9Xs in competitive IMAC to this day. Oh, and it had a touchscreen. Something just now coming to mainstream radios. But all of that radio resolution means nothing on the airplanes until... they spend $75 for ONE servo.
Which sequence do you fly? I'm gonna start out in basic next year (hopefully) and move up to sportsman before the end of the year
 

SlingShot

Maneuvering With Purpose
Not sure if this is sarcastic but that's like comparing apples and matchbox cars...

Haha.....not sarcastic. I had a sense things were better, but there were about 30 years between samples. ;)

This is the first I had heard about the nitty-gritty of precision.
 

TooJung2Die

Master member
But all of that radio resolution means nothing on the airplanes until... they spend $75 for ONE servo.
I can appreciate that kind of precision and paying what it costs. Another hobby of mine is target shooting. I've paid good $ for accuracy. If my flying skill ever approaches my shooting skill I'll pay $75 for servos. Sadly I have a lot of flying practice ahead of me. 😁
 

OliverW

Legendary member
I can appreciate that kind of precision and paying what it costs. Another hobby of mine is target shooting. I've paid good $ for accuracy. If my flying skill ever approaches my shooting skill I'll pay $75 for servos. Sadly I have a lot of flying practice ahead of me. 😁
The spooky thing is that I'm gonna be paying $180 per servo in my next 120cc.... yay
 

willsonman

Builder Extraordinare
Mentor
Which sequence do you fly? I'm gonna start out in basic next year (hopefully) and move up to sportsman before the end of the year
I've been flying the Basic routine but I have absolutely no intent on competing. I have no use for it. I have been having so much fun becoming a better pilot by intentional practice that I have no desire to compete. My other club members keep asking. I'm just not a competitive person. I've even had people ask if I compete in the scale competitions... Nope. NO desire.
 

willsonman

Builder Extraordinare
Mentor
Haha.....not sarcastic. I had a sense things were better, but there were about 30 years between samples. ;)

This is the first I had heard about the nitty-gritty of precision.
Yeah, I think that some of the more detailed and nuanced discussions have nearly all but left the FT community. Sad but true. You just have to find the right person and ask the right question. It's part of the reason why I'm so completely transparent with everything I do.
 

willsonman

Builder Extraordinare
Mentor
I can appreciate that kind of precision and paying what it costs. Another hobby of mine is target shooting. I've paid good $ for accuracy. If my flying skill ever approaches my shooting skill I'll pay $75 for servos. Sadly I have a lot of flying practice ahead of me. 😁
I do too! However, just because you are not at that level yet does not mean you do not need to avoid it altogether. Bigger does fly better but the cost of entry does go up as you flay larger aircraft. I think that same principle applies here. The 150cc 43% Extra my club president has for IMAC does not necessarily represent his skill level, but what he is shooting for. Don't get me wrong... He just completed 7 years as the North East Regional Director for IMAC and he has taught countless courses on scoring and judging. He's a great pilot. He's gone to nationals but never been one of the exceptional pilots that makes everyone wish they had never picked up a transmitter.
 

Maxxnut

New member
Wilsonman, I have the same kit that I bought new, and am building the same plane, with a twist....I am putting the thing on a "diet". If I can help you with a pdf scan of any of your missing parts, just let me know, and they can arrive to you via email. If you want to see what I am up to, and the reason I can supply you with scans of any parts, look at my build thread here >> https://www.rcgroups.com/forums/showthread.php?2073875-Top-Flite-P-51-on-a-diet. The last time I touched it was 3 plus years ago, but now that I am retired, I will get back into it. I am soooo glad I found your thread because I want to really watch you build the body and see if you end up with the same "condition" that I did, which is way too hard to define in an online forum... will have to show pictures when the time comes. It has to do with former #9, and the way it makes the body shape change, so don't glue in former 9 just yet. I have marked up the plans and build book with all kinds of notes, and am willing to share. BTW, I had a personal conversation with David Ribbe about wing tip wash out, and if you notice, it is NOT on the plans. He did that because he said the no one pays any attention to it anyway, but the real amount of tip washout is 2 degrees. The "feet" on the wing ribs set the washout due to the wing being built upside down, but the wings get warped when the sheeting on the other side of the wing is applied.
Neil
 

willsonman

Builder Extraordinare
Mentor
Wilsonman, I have the same kit that I bought new, and am building the same plane, with a twist....I am putting the thing on a "diet". If I can help you with a pdf scan of any of your missing parts, just let me know, and they can arrive to you via email. If you want to see what I am up to, and the reason I can supply you with scans of any parts, look at my build thread here >> https://www.rcgroups.com/forums/showthread.php?2073875-Top-Flite-P-51-on-a-diet. The last time I touched it was 3 plus years ago, but now that I am retired, I will get back into it. I am soooo glad I found your thread because I want to really watch you build the body and see if you end up with the same "condition" that I did, which is way too hard to define in an online forum... will have to show pictures when the time comes. It has to do with former #9, and the way it makes the body shape change, so don't glue in former 9 just yet. I have marked up the plans and build book with all kinds of notes, and am willing to share. BTW, I had a personal conversation with David Ribbe about wing tip wash out, and if you notice, it is NOT on the plans. He did that because he said the no one pays any attention to it anyway, but the real amount of tip washout is 2 degrees. The "feet" on the wing ribs set the washout due to the wing being built upside down, but the wings get warped when the sheeting on the other side of the wing is applied.
Neil
I appreciate the reference to your build. I'll have to glean over it and see if I can learn a few things. Sadly, the fuselage came to me partially completed. I've not really looked at it just yet to see what stage it is in but I suspect that this former is already in place. I have no intention of making this model super scale. I've known many folks who have owned one over the years and they all say that they just fly great as-built. That's really what I'm after. If I pick up a few more scale points along the way, cool. The focal point, for sure, will be the motor but overall this entire airplane is meant to be somewhat subtle.
 

willsonman

Builder Extraordinare
Mentor
I did have a chance to review your progress, @Maxxnut , and I have to say, that is quite a bit of effort to make this thing light. Regardless, I did do a quick once-over of the fuselage and it looks like F9 has not yet been installed. Looking forward to your thoughts on that. I'm a ways off from that part of the build.

The holiday week was filled with mostly cleaning and cooking with little hobby time. I did manage to get the V-stab sheeted and the tip put on. Again, This part was missing so I went back to the hard balsa and made my own block and had to cut/sand it to shape. It took the better part of 30 minutes just to make that part, then I had to install it and then plane/sand it to the airfoil shape. I'm pleased with how stout it is so there's that.