42" Tunnel

[properchopper]

Good times in Camarillo

https://www.youtube.com/watch?v=AQCU2ljOIbQ

[RaceMechaniX]

I miss Camarillo. That was a great pond hidden from the public.

[Peter A]

So I got the boat out on the water on Saturday. It is fast. It's main problem is porpoising as it gets up to speed. It takes about 50 meters for it to settle but then runs flat and smooth. By porpoising I mean the bow really bounces.
CG is just forward of 30%. The strut is set fairly high, I have not altered it from where it was. I will have to measure it and take a pic tonight, but it is probably 16-18 mm above the ride pads (centre height).
So at this point, any suggestions as to how to get rid of the porpoise?
For the turns backing off the throttle a little and it corners well, as soon as you go wot it porpoises for half the straight before settling back down.
Do I try propping down and take off some speed to stabilise? I ran an X455/3 and P245, both props have been detongued a bit.
If I move the CG forward it may nose in and hook when cornering, it can do that now with a little too much rudder, dual rate is already at 30%.
Overall I am stoked with the boat having paid NZ$650 for it. Just need to dial it in a bit more. Any good suggestions to try would be great.

[koen]

Hi Peter i have messured my prop seting it's 13mm centre propshaft above the ride pads.At what angle is the propshaft? is it positiv or level whit the ride pads, you can play whit this

[RaceMechaniX]

Peter,
On my AM Conquest the prop is quite high in the tunnel, about 10mm above the bottom of the pads. Try shifting the weight forward to hit 33-35% COG. Or try adding a little negative strut angle.

[Peter A]

The prop height is quite high, shaft center height is 17mm. The shaft is also pretty level. I am having trouble uploading pics again. I will try dropping the strut height a little and the adjust this one at a time.

[Peter A]

Ok so I ran again on Saturday. Leaving the CG at 30% and bringing the strut down 3 mm resulted in a blow over. So I put the strut back up and moved the CG forward to 32%. This sorts the porpoising out quicker and it is much smaller hops. With an X455/3 it ran 94 kph, and with a P250 96 kph. I am sure it has more but I want to set it up to run ovals really, so I will continue playing around with the CG and strut height.
I also ran my DF 35 Pirate with a 6s set up and ran just under 98 kph on a ABC 1816, was happy with that.

[RaceMechaniX]

Peter,
Try dropping the strut back down 3mm and put some negative angle in the strut. This will help push the nose down and reduce the chance of a blowover.
-Tyler

[Peter A]

So I got in another run on Saturday. CG at 33% droppped the strut about 3mm and run a detogued P240. As expected it was a little slower, not much, but it was quite happy going around until a connector melted off. It was one that was done by whoever set the boat up so that is not a big problem to rectify. I had done 8+ laps. Getting it closer to where I want it.

[Peter A]

So the boat got it's first club day racing on Sunday. Due to losing a cell on one of my 6s packs I had to change it to 8s. Ran on an X460 detongued and cupped and a P250. The water was rough and I won two heats and second in two heats, but I won the day on points. Not bad. The CG was at 34% even without the 6s packs and worked well in the rough water. I am enjoying this boat.