Proboat 772

Any progress on the cannard spoiler or 1/2 throttle problem??

mopartybob

throttle problem solved.(changed servo arm),have yet to test under full throttle conditions,need to do that to baseline and log results before any further tweaks and adj.,.....will keep you informed,have you ran that pond disturber yet,lol...(QD25 Miss Elam).....

Proboat 772

Mopartybob

No, thats going to be for next spring as I'm down South for the winter. We're using the Quickdraw wrap to center hot pipe on this one, so it should move along. Still have to convert it to the throttle to bellcrank system, but otherwise my son's Miss Elam is all put together. Most likely there will have to be some aero changes to keep it stable but we'll take it incrementally. Keep us posted on your progress.

Over the winter, I'm looking to build a Rivett Shovelnose from Zipkit, and if time permits I think I'm going to scale up a model I drew up and built when I was 15. That was 53 years ago and a lot has changed since then. It was a 1/8 scale of a 266 Hydro that a friend of my father raced in the Buffalo NY area. 1/4 scale would bring it to 51" long - should be fun if just for sentimental value.

Dick

mopartybob

HJ,you the man....,I finally was able to get back in the water today,with the throttle fixed,and a b/s/p 6717/3 this thing exhibited the truth in your statement,with the rear wing swept up 15*degrees,it see-sawed it's way around the pond at about 40-45+.....what i mean by see-sawed is that it pitched off the sponsons and prop to the point that it resembled an out of control bucking bronco....[:@] I'm gonna reset the wing to 5*degrees and get a new baseline towards baa-lancing the darn thing,I've got the clue now as to re-trim the hull for the speed it wants to run, will post vid of this run as soon as batteries recharge.....mine and vid-cam....[:-]

martno1fan

yeahaa [sm=drowning.gif]

Hydro Junkie

That is why I said to put the wing to a 0 degree setting and work from there. Some nitro scale racers will go so far as to remove the wing and tails and then balance their boats, get them dialled in and then reinstall the tail set. That way, if the tails or wing get damaged, they can be taken off without any loss of performance. All that is needed is to adjust the wing to have enough lift for the weight of the tail set.

mopartybob

Here's a link to yesterdaze runnin... http://www.vimeo.com/605591

G Doggett

As has already been stated, the c/g for a boat this size is around 2-3 inches behind the sponsons.
If this cant be achieved without adding lots of ballast the most effective way to lift the stern and help hold the bow down is to run the strut at an angle .
If you look at most full size hydros they run a solid shaft at around 3 degrees angle. This coupled with a lifting prop will make a huge difference.
On my gas shovel nose hydro the strut is 3 degrees and it runs nice and flat with the sponsons just touching the water and dancing from side the side in true vintage style.
IMO play with the strut rather than the rear wing.
Graham.

mopartybob

thanks G, i'm already runnin the strut about 3* shimmed,and runnin about 30oz. lead (25 on the canard,5 in front of the tank) the cog was initially about 7 1/2" behind the front sponson,and that was with 25oz on the canard,by adding the 5oz to in front of the tank,brought the COG to 4 1/2" behind the front sponson,I thought by playing with the rake of the wing I could get it trimmed right without adding more weight,but it looks like I'll just poop-can the wing (for now) and get a new baseline for trimming,now that the engine/prop combo seem to be matched effectively.... Oh the joy of the pain.....

G Doggett

Aaaah, sorry I thought this boat had the strut flat ( 0 degrees ).
You could try a high lift prop such as an Octura 14 or 16 series.
As you have figured out by now , all of these mods and tweaks are really trying to compensate for the fact that the c/g is way too far back on this great looking scale boat.
Unless you are prepared to reposition the motor and heavy hardware further forward your only option is adding ballast.
I hate adding weight to a boat but sometimes it is the best solution.
How heavy is your boat ,ready to run ?
I have seen some very succesful 1/8 scale hydros that tipped the scales at 20lb, in fact in rough water this weight was an advantage.
Graham.

mopartybob

Hi Graham, The boats runnin weight right now is about 17lbs. I wanted to experiment playing with wing tuning to see cause and effect,(being a novice with hydro's) I just had to find out...If you look at the other vid of this boat on my site,you'll see it's alot more stable at lower speed with the 15* rake,and using a p280/2 blade,(the lower speed was due to a too short servo throttle arm),without the mod to the wing,it would become a one-point hydro (LOL) as it rode the prop at about 1/2 throttle (about30mph)the current vid,I'm using a 6717/3 blade which I'm going to use thru-out testing/setup stages as this prop really matches/unloads this motor effectively,I also hated to add weight but seein that you mentioned it could be an advantage,I'll try to keep it minimal and under 20lbs....lol.... the coming test runs sure are going to be interesting,thanks again buddy.....

Hydro Junkie

Bob, a common saying in scale hydros is "Lead is your friend". If used very cautiously, lead can benefit your boats running ability. As Graham said, it should be used as a last esort and not as a bandaid to fix a bad balance job. Like adjusting the wing, it should be added in small amounts until the boat runs as desired. Prop selection and thrust angles play an important part as well, so it's best to run, tweek, run AND THEN ADD. Ballast isn't something you add sitting on a scale, but at the lake while dialling the boat in. Are you still using a clutch on this boat?

mopartybob

thanks buddy, although truly not the last resort,tis the most easiest....,now that the engine/prop combo are tuned, it's just a matter of weight and see just how much is enuff,you've mentioned adding weight to the left sponson,is that to help counteract prop dancing..? as always,your advice is very welcome....NO clutch

Hydro Junkie

You need to add weight to both sponsons, but if you have a left side lifting problem, put a little more on the left. Something else to consider is that since the sponsons are hollow, when you put the weight on the inside, more will be in the front than you are presently running on the sponsons. This might let you drop a few ounces from inside the cockpit, but that will take some experimentation

mopartybob

just recieved NEW SPEEDMASTER turn fin,in relation to the sponson ride pad,should this critter be mounted on(towards) the inner,middle,or outer step?? what changes also (in handling)when mounted closer/further away from the sponson,(if any,) are related to the different mount locations?

G Doggett

I always mount the turn fin in line with the outer edge of the sponson ride pad.
I use a straight fin but run it angled in about 5 degrees.
However 10 guys will probably give you 10 different set up recommendations !
Graham.

mopartybob

thanks graham,I hope i didn't start sumthin,,I'm sure someone would have the answer to cause and effect of above mentioned.....thanks all

mopartybob

after lots of down time,(mostly work n bad weather),I finally got around to some "simple spoilers,.016 sheet alum. x 4", secured with servo tape....[:-]instead of placing them on the front canard,i opted to put'em on the center/nose ? stab,where I think [:@] it would have more effect here and not disturb the airflow from the front canard that directs airflow "under" the hull,I have other idea's to manually operate these things,but really just experimenting for now,will post results asap (weather hold)....comments welcome as always,these are in a way meant to counter the effects of bad COG,w/o adding weight,or extreme mods......but we'll see

Hydro Junkie

You would be better served by putting a spoiler on the rear of the front wing since the location you are on now is much to small and too close to the ramwing to really have much of an effect

mopartybob

thanks HJ, I'll try there also and see which IS most effective....[8D]

Proboat 772

Interesting concept - let us know how effective it turns out to be...

Dick T.

mopartybob

will give this a go this weekend....hopefully ([:-]) all ballast has been removed to set new baselines for testing,current COG-5" behind sponson, front spoiler AOA-23*,center-0*,rear wing-5*, I may be beating a dead horse here,but I think if you can remove any excess weight and use airflow to help keep the critter from "blowin off",so much the better .....[&:]

martno1fan

Good to see someone actually using those wings the way they were intended to be used

mopartybob

bad weather last week,will give it a go this weekend,I've found a much simpler way to adj. the rear wing,simply elongate the rearwing screw holes to about 1/4" down,this will make it adjust from 0* to apprx.10*- AOA....too easy....pics will follow ....

mopartybob

was able to test today,the spoilers worked quite effectively,(sorry no cameraman this round),total ballast removed in lieu of spoilers,rear wing set to 5*-,= 25 Oz. (WOW)....[)] I'm able to run the course at WOT,hull is tickling the water on 1-2"of sponson,but still a little too high off the water 3-4" at times, but would settle to 2"...it's just a case of minor tweaking now....[8D] will be in vegas next week, so further testing will have to wait ...all in all, this has been a great learning curve for me,this being my first hydro, I've learned alot from everyone....thanks alll