Help! Sport Hydro Lost Speed with new CG

[Brushless55]

Sounds like a plan. A little cup at the tips might be all you need to settle down the rear. A neutral strut is almost always best as far as putting the power to the water. I was kind of surprised you are running the 1717 successfully on a UL1 set up. I would think that would be too much prop for that motor but you seem to be happy with it and that's cool. I wouldn't worry too much about the compression of the flex cable. The prop loading and unloading from the water as the tail hops is what can put the hurt on your electronics. You using .150 or 3/16" flex?

educate me on this one....
what does putting some cup on the tips settle the hull down?
thanks

[longballlumber]

Gave up. Moved the motor back to the original position. I was getting ready to glass the insides of the motor mounts tonight, but then I thought it might be OK as-is. There is only glass on the outsides. Anyone try this before?

Looking forward to getting the 'hop' tuned out with the 1717.

BTW - Is there a battery capacity limit to P-spec in MMEU? I'm going to need to add weight up front with the new motor position, so I'm going to try to add it in battery capacity, not lead!

[ATTACH=CONFIG]97425[/ATTACH]

What happens when you don't reach that "magic" number you’re looking to repeat from last year?!?!?!?! You're putting a lot of work into those changes not knowing if that was the problem.

I moved my motor 2+ inches forward and I feel like it's running just as good if not better than last year... Not trying to be a stick in the mud, but I feel like you working really hard trying to reach a certain MPH mark. I am willing to bet most of the boats in our club are very close on SAW speed as mine. You will be miles ahead if you figure out how to minimize scrubbing speed while turning.

FWIW, I ran my boat one run on Wednesday using Eagle Tree…
Speed Peak of 52mph and Average Speed of 47mph =’s much slower speed in the corners
Peak Amp Draw 139 amps (on takeoff) and Average of 90 amps with several spikes of 100 through ought the run =’s TOO MUCH come July and August…

The data logging is relative; those MPH marks are one data point and one point in time during the logging.

We'll get it figured out..

Later,
Mike

[longballlumber]

BTW - Is there a battery capacity limit to P-spec in MMEU? I'm going to need to add weight up front with the new motor position, so I'm going to try to add it in battery capacity, not lead!
[ATTACH=CONFIG]97425[/ATTACH]

Oops... The whole reason I replied...

In the NAMBA rule book Section 28, Page 5 (page 96 in the PDF file)... there is a 10,000mAh max in the P-Limited Classes

Later,
Mike

[Brushless55]

Oops... The whole reason I replied...

In the NAMBA rule book Section 28, Page 5 (page 96 in the PDF file)... there is a 10,000mAh max in the P-Limited Classes

Later,
Mike

kinda wish there was not a limit..
I am seeing some lipo brands no longer selling 5000mah packs and moving up to 5300 and 5500 sizes +

[Shooter]

What happens when you don't reach that "magic" number you’re looking to repeat from last year?!?!?!?! You're putting a lot of work into those changes not knowing if that was the problem.

Good point, and yep, a lot of work. Hopefully I don't end up full circle. It could have been a bad flex shaft as well. I noticed when holding the motor shaft that I could turn the prop (clockwise) almost 1/2 of a turn before I had solid engagement. That's a lot!

....and I DO need to work on the turns. I noticed when you had me lower the strut a couple weeks ago, it turned a lot better. I think getting the a$$ end out of the water really helped it.

[Shooter]

Reason I asked about capacity is because I was thinking of adding batts for weight, but it's not going to work unless I can stuff them into the sponsons. The weight just isn't as effective in the current location (needs to be way up in the tips). It's not a bad idea though...running 10,000mah would keep the voltage higher.

[T.S.Davis]

I would be willing to bet that you're talking .02 volts difference at the amperage we're burning. You could get the same effect from higher C ratings if you can believe those. FAKE! haha The problem with carting the extra weight in a sport is that you have to accelerate that weight back out of the turn. Kinda defeats the purpose.

I'm only running 4400 mah. I haven't got mine figured out yet though. Boat runs flat with no bobble so I'll keep screwing with the strut until I find the sweet spot. I have no plans to add weight but we'll see.

[Shooter]

I would be willing to bet that you're talking .02 volts difference at the amperage we're burning. You could get the same effect from higher C ratings if you can believe those. FAKE! haha The problem with carting the extra weight in a sport is that you have to accelerate that weight back out of the turn. Kinda defeats the purpose.

I'm only running 4400 mah. I haven't got mine figured out yet though. Boat runs flat with no bobble so I'll keep screwing with the strut until I find the sweet spot. I have no plans to add weight but we'll see.

Ouch. Didn't realize it would be that little of a difference in V. ....and Dang! I forgot about those dreaded turns again. Yep, you're right. More mass to accelerate...

I can't believe yours isn't blowing off without weight up front? That's good news! Is your motor forward? I need a peek at this thing.

Mine was light as a feather last year with no added weight anywhere. I remember weighing it. I think it was JUST under 5lb, run ready. Tony would pick it up and say 'woah.....that thing is light!' when pitting.

Unfortunately, the new motor position forced me into putting 4oz in each sponson tip to get the CG back....Not happy with that at all. We'll see how it goes.

[T.S.Davis]

It is blowing off right now. Still working on it though. I would prefer to find the right strut height and angle over adding weight but who knows. I may have no option in the end. I also have the wing to use as I see fit.

[Shooter]

Forgot about that WING! That should help, huh?

I tried a canard last year to add the weight only when I need it, right? Well, it fell off, and then I think Bob ran over it. It wasn't a happy ending. I think someone yelled at me for contaminating the pond with boat parts.

[T.S.Davis]

Who knows. We could have three pages of arguing about wings on a sport. I will say this........the real hydros have them. What do they know though.

Next time your chugging in traffic. Say around 50mph. Stick your hand out the window. Feel anything at all? Tilt your hand a bit and you can feel the force pushing up or down. Take your pick. Your hand wants to be straight if it can. That's my theory with the wing. Valid? Who knows. May take a while to figure it out.

Looks cool.........gotta look cool.

[Shooter]

Good analogy with the hand out the window. So I take it you have it set to zero? Or will you add some lift to the rear when level?

With our scale speeds, wings and canards should be 2-3x as effective?! I wonder how much of an angle and/or my airfoil needs to look like to provide 16oz of downforce at 50mph. hehehehe.

[T.S.Davis]

For another mental what if........what if the prop thrust cone didn't need to support the boat? Or if maybe it only barely needed to support it?

Valid? I don't know. I'm just another idiot with an idea.

[Shooter]

From one idiot to another.... I think you are the smart type of idiot.

If the wing supports the tail, we will probably pay for it in drag?? but that might unload the motor a little?? not as much side load on bushing?.... ah...what do I know?? My PT has been dragging it's a$$ for 2 years until Mike told me to lower the strut last week. Comical. You can't argue with the speeds I was getting though! Watch the vid in post 1...she's a low rider.

[longballlumber]

After reading all those post between you two I broke into song... "my wing-a-ling, my wing-a-ling I won't let you make changes to my wing-a-ling..." hahaha

Later
Mike