The new guy...

[bogieboy]

Just figured i would say hi...LOL joined up for more info on a boat i just got, an old Graupner Monster vee. Boat came with a resistor speedo powering 2 graupner speed 600 motors, thru a 2:1 gearbox, out the back thru a strudder with a carbon Graupner 47.5mm prop with 1.2 pitch.... so far i swapped out the speed 600s for a 2150kv bruahless system, and plan on running on 3s...

i had rewired the speedo to power just 1 of the motors since it was slow as snot with them powered in series (and i knew it wouldnt have an icecubes chance in hell of running both motors parralel on 3s) and the few min it ran, porpoised like mad... but ran nice and fast...LOL for a wiper speedo brushed sealed can motor....

Anyone with tips on the porpoising?

[Fluid]

There are several common reasons for propoising:

- the hull design limits the speed, too fast and it runs poorly
- the CG is too far back
- strut is angled up at the prop end
- prop is running too deep or too shallow



:

[bogieboy]

There are several common reasons for propoising:

- the hull design limits the speed, too fast and it runs poorly
- the CG is too far back
- strut is angled up at the prop end
- prop is running too deep or too shallow



:

I doubt that its the hull design, as it was billed as the fastest stock electric of its time when it came out, designed to run 14s nicads, and when i get it up full throttle even in stock form with 3s lipos, it will porpoise... i have tried strut up, strut level, strut down, all to no avail...cant really adjust prop depth, and i have tried shoving extra weight (an extra 3s lipo pack in the battery tray and even stuffed up further than the tray.)up in the nose of the hull, which hasnt really done a whole lot either...

[bogieboy]

Please forgive the messy bench....LOL lots of projects and hobbies here...LOL but heres a pic of what we are working with...


And a short vid of it running the stock driveline, twin speed 600s in series, on 3s (11v on a setup originally designed for 14-16v)

[NativePaul]

S14 was a restricted class and not as fast as Mono2 was at the time despite the extra 2 cells. I Don't know the boat as I was on a break from racing when it was out, but it may well have been designed with some rocker from the factory to get the nose up on the limited power they came with. Put the hull on a flat surface and if it curves upwards at the stern, that is rocker, and making it go faster than its design speed will always result in porposing.

You could try fairing it flat with filler, or what we did to race RTRs with rocker is cut off the transom just before the rocker starts, cut the now separate transom off about 5mm forward of the transom, turn the transom around and glue it inside the new back of the hull, creating shorter hull with a new transom with a sharp 180 degree edge and no rocker.

[bogieboy]

If i am understanding you correctly, there isnt a rocker to it, bit it does look a little deformed under the r of monster vee, would that be causing the porpoising?


Also, i havent run it on the new brushless setup yet, but current cg seems pretty good, at 9 1/4" forward of the transom on a 28 1/2" hull...

[bogieboy]

Might as well add a pic of the box, and how the boat is currently laid out....

[bogieboy]

And....LOL heres another graupner hull thats seemingly identical doing exactly what i want mine to do...LOL i wonder if i just need trim tabs or something? Seems all the fast graupner vees have them....

[Norwest]

Needs info and more reading on his part to help him out. I'll help him.

[Norwest]

Post info not needed as suggestion, thanks!!

[bogieboy]

Got to run it on the brushless, as set up in previous pics, not too bad, definately more peppy, also much smoother with the improvised trim tabs (soon to be replaced by real adjustables, as soon as they show up...LOL as for gutting the boat, maybe in the future, i am pretty happy with it for now. If i am buying hardware for a boat its gonna be for building a gasser, in the 48" range....i have an abundace of professional grade stihl brush cutter engines (perk of being a certified tech) that i would love to convert to rc boat use... couple of 27cc, a 32cc, and a 36cc 4 stroke.... one of those should work well....LOL not looking to break any records, just a larger fun boat that runs for a bit longer.... probably either gonna get a fiberglass hull and fit it out or a zippkits hull.... one or the other.... few tempting fiberglass hulls on ebay....

Anyways heres the vid on 3s with the new brushless....

[Norwest]

Now from what I gather your happy with it.

[bogieboy]

Now from what I gather your happy with it. I'll remove my post!

Not a problem Norwest!!! Someday i will gut it for a straight driven setup... for now its plenty fun...LOL actually sitting in the car at the edge of the erie canal in upstate ny waiting out rain to run my second pack thru the boat tonight... :-)

[bogieboy]

So...LOL i cant leave things well enough alone.... found a prop shaft that was the right size to convert my 4mm setup to take 3/16 props.... good old Octura mad the shaft, 4mm and the prop end steps up to 3/16 with a drive dog.... so i picked up a few plastic props to play with.... found that this boat really likes a 52 mm 1.4p 3 blade.... motor is about 140-150° after 2 back to back packs on 3s... and its about 5mph (according to the eyeball) faster than the 47mm 1.2 that was on it when i got it.... now i may just have to invest in a metal prop...LOL

current back end with the trim tabs i got and new prop...i may have to flip the trim tab adjusters over to make them hold better, or go longer screws... one of the 2....LOL but it planes out nice right now....

[Norwest]

delete