Tim,
Simple questions, long answer! ;D
I don't adjust the tabs during a race as it is a bit too distracting while screaming around a course with a few other boats and with the JR R1 radio I am using the third channel on it is pretty slow to use, I need about 10 clicks to get a noticable difference. Just driving is enough to worry about! In testing time I play with them a fair bit, especially when I am changing props. I can change the ride of the boat on the fly and not have to bring it in to do it. You can do runs to the radar and see what difference trim makes to speed, all in one run!
If I was using an R756, which had a dial for the 3rd channel, I would probably use it more in a race. Actually it could be quite handy. Even with the tank next to the engine the weight reduction of the boat makes it ride looser near the end of the run. Also the water tends to be rougher towards the end of the race. If you had it set up right you could run your boat loose (and fast) for the start of the race when the water is calmer, get the lead, then tab it down so it is a bit safer and stays on the water when it gets lighter and the water is rougher. This would require a lot of concentration and self discipline, but may be well worth the effort! Particularly for 90 monos where the weight change is significant, the speeds are higher and you generally can't hold full throttle all the time, and the water gets quite rough. For smaller displacement boats that are slower, you can hold full throttle, the weight does not change much and the water does not get rougher in the race then the advantage is probably nullified by the extra weight and complexity.
Most mono hull designs, including Kingcrafts and Calcrafts, tend to drop the nose when they heel over for a corner. This is a problem because with an increasing vee angle at the bow, these boat dig the keel line in and the boat will "hook" in the turn, or maybe even spin. The conventional solution to this is to use split tabs, the inner tabs are adjusted for ride (wet or loose) and also for countering torque roll. The outer tabs are generally raised, and quite a bit, so that when the hull heels over in the turn the outside tab comes into contact with the water and reduces the pressure on the bow so the the bow does not dig in and cause the boat to hook.
The problem with this is that with the larger and more powerful engines the right inside tab is generally down to counteract torque and to stop the hull from blowing off the water. This tab is down far enough that it tends to over-ride the outside right tab in the corner, the boat runs to wet in the corners and tens to hook.
The Fischer's approach to this problem (from back in the Youngblood days) was to have single tabs that were radio adjustable, and to use fancy radios that could mix the rudder with the tabs, such that as the rudder was turned the tabs would come up. This potentially gives the best of both worlds, you can have the RH tab down in the straights to control the ride, but in the corners this tab came up to keep the pressure off the bow. You dont have two tabs next to each other that are fighting each other with vastly different settings. You also have the handy ability of being able to change the ride of your boat at any time.
So I built radio tabs, and bought an R1 radio which could mix the tabs. I also made my tabs go very close to the keel line, much closer than normal, so that they would be more effective in controlling the ride in a straight line. I used this for quite a while, probably about 8 months, but I finally noticed a phenomenon that was causing me to crash the boat. I noticed that I would flip or dive the boat on the exit of corners at high speed, just as I was letting off the rudder I would loose it. What was happening was, with the rudder still slightly turned the tabs were also up and the boat was no longer heeled over, so it was suddenly like I had pulled the tabs up a lot in the straights! It took me quite a while to figure out this was happening.
So now I split the tabs, the outer ones are fixed, and the inner ones are radio adjustable but are no longer mixed. They no longer really need to be radio adjustable as they are not mixed anymore, but I left them adjustable as all the hardware was already on the boat to do it! I am thinking of getting an R756 radio again to make it worth while having the tabs so I can use them as I described at the start.
There. Phew! That is why I have radio tabs, and that is what they could be useful for! If I had it all to do again would I bother? No, probably not. Since the radio tabs are all custom made it is a lot of work to get a system going that is realiable and does not kill the servo if you spin or flip.
I hope that answers your question! ;D
Ian.
