Hospital Hop...how to stop it?

[Shooter]

I think it would be considered a vent. This is what it looks like, more or less.... It can be tuned to achieve the proper amount of bleed-off.

[dreamland s4]

Ride pads work! Thanks to detox!

[InspGadgt]

I was thinking about "the hop"...
Tony's UL did the same thing in the beginning,
looking back I believe it was a combination of factors...
first it was a little lose and started flying and then the first sponsons
would take off and land hard rebounding and throwing the hull to the other side
and so the hop started, violently like described earlier. The reason
it started bouncing side to side like that and get worst, is because the
turn fin would hit the water at an angle and push the hull
up to the other side again and then the vicious cycle would start
over and over again... if you can keep her nose down this dance
probably would not happen.

just my shot at it...

This is where I'm having an issue it seems...when watching my boat on the straights it looks like the turn fin is lifting the right side of the boat out of the water. Then when it hits a rough patch of water it starts the hop.

[InspGadgt]

It's not just depth, but also angle... I haven't run mine yet so I can't give you good answers... I've read to the effect that 1 1/6" of depth with a 3-degree downward angle works... I think that was Tony's setting (Properchopper)...

How are you adjusting angle? I can understand depth s with the strut but the stuffing tube goes all the way through the strut so the prop angle can't be adjusted independently from the stuffing tube...which is just depth.

[NativePaul]

This is where I'm having an issue it seems...when watching my boat on the straights it looks like the turn fin is lifting the right side of the boat out of the water. Then when it hits a rough patch of water it starts the hop.

That means the bend/curve in your turn fin is not parallel to your running attitude, you have to tilt the bottom of your turn fin back a little more, to get it parallel and stop it generating lift in a straight line.

[properchopper]

I did these mods and the UL-1 settled way down. (see vid below)

#1 : Reduced the AoA AND vented the air traps with some diversion strakes

DSC01160.JPG

went to a squared-off turn fin : (picture prior to altering AoA)

DSC00993.JPG

https://www.youtube.com/watch?v=yicE1_TfDDY

[properchopper]

How are you adjusting angle? I can understand depth s with the strut but the stuffing tube goes all the way through the strut so the prop angle can't be adjusted independently from the stuffing tube...which is just depth.

A simple way to allow strut angle adjustment is to [CAREFULLY] shorten stuffing tube so that it only extends roughly3/16" into the strut.Install lead teflon bushings for the propshaft.

[InspGadgt]

That means the bend/curve in your turn fin is not parallel to your running attitude, you have to tilt the bottom of your turn fin back a little more, to get it parallel and stop it generating lift in a straight line.

I've got it turned back as far as it will go...it is still lifting the boat.

However today I did try with a 3/8" air dam...it was rougher out there but my boat was still more stable than last time I ran it.

[InspGadgt]

I did these mods and the UL-1 settled way down. (see vid below)

#1 : Reduced the AoA AND vented the air traps with some diversion strakes

DSC01160.JPG

went to a squared-off turn fin : (picture prior to altering AoA)

DSC00993.JPG

https://www.youtube.com/watch?v=yicE1_TfDDY

That's what I was thinking on doing with my turn fin...I hadn't thought of a vented air dam. The flat air damn I tried today made it really difficult to get the boat moving so I was thinking about an angled air damn but I like your idea too. How tall did you make your air damn?

[InspGadgt]

Has anyone tried this: https://www.offshoreelectrics.com/pr...d=hug-ul1-foil Any feedback on it?

[InspGadgt]

A simple way to allow strut angle adjustment is to [CAREFULLY] shorten stuffing tube so that it only extends roughly3/16" into the strut.Install lead teflon bushings for the propshaft.

Looking at the strut replacement part listed: https://www.offshoreelectrics.com/pr...od=dh-aqub6950 It looks like the strut should already have a bushing and the stuffing tube should be shorter.

As much as I've enjoyed this little boat and how cool it looks...I'm getting a bit frustrated with not only all I have to go through to get it to keep up with a UL-19 on 4s...but also with the quality control issues I'm running into. First the boat starts to crack along the seam on the inside left sponson. Then I notice the motor does not line up properly with the stuffing tube. Had they made the motor mount adjustable that would have been an easy fix to compensate for any manufacturing misalignments. The rudder has no break away...and my motor strut is not adjustable in angle, only in depth. The motor wires were routed poorly and interfere with battery installation. I had to re-route the wires over the top of the motor and the wire lengths are just barely long enough to work. And the ESC has to be re-programmed every time you plug in the battery...just really poor choice in electronics there. I'd would have rather this boat be offered in an ARR format so I could use my own electronics. Some of the choices made in manufacturing this boat make sense if it were a one off build...but in a mass produced environment where mistakes occur regularly a little bit of added adjustability in the design would have compensated for the inaccuracies. I don't see how they can claim the boat is capable of 65+mph when it starts losing stability around 43mph.


Don't get me wrong...I don't think this is a bad boat...I really like it a lot. I just thing things could have been done better with a little more care and foresight.

[properchopper]

There are auto mechanics schools where the students are given a poorly running engine and their assignment is to find out what's wrong and fix it. They become better mechanics after this learning experience. Sounds like your experience with the UL-1 parallels this (of course only if you choose this way of looking at it ). I know that my personal experiences in boat building follows this closely ; each boat I build teaches me something so the next one comes out even better. The UL-1 is about a decade old and when it was introduced it was one of the best values for a nicely performing rtr. Needless to say the "Igottagofaster" bug bit and the hull was soon pushed past its design limits - but even so it is a decent value (plus remember that to hit a entry level price point the build labor costs are kept down by using nine year old laborers who make cukoo clocks on their morning shifts). To elaborate, one of my bespoke FE30's will set you back double what a fresh rtr UL-1 or Proboat version costs but won't need ANY fiddling for its lifetime - e.g. my personal FE30, the VERY FIRST production model @10 years young) is now current 2018 SCSTA high points holder and the ONLY thing that gets done to it year after year is to grease the flex after every race, put a drop of oil front & rear on the motor bearings, and once a year replace the strut bushings.
Hang in there - it gets better

[InspGadgt]

Thanks...I know it will get better. I've been a bit frustrated is all.

So back to your earlier post where you put the air damn on...the wood under the sponsons...to me it looks like you did this to decrease the angle of the sponsons and to eliminate the step in the sponsons. Is that what you were intending or am I reading it wrong?

[properchopper]

Thanks...I know it will get better. I've been a bit frustrated is all.

So back to your earlier post where you put the air damn on...the wood under the sponsons...to me it looks like you did this to decrease the angle of the sponsons and to eliminate the step in the sponsons. Is that what you were intending or am I reading it wrong?

you did this to decrease the angle of the sponsons ----- yes


to eliminate the step in the sponsons. ----- NO

[Fluid]

One of the initial “problems” with this hull was not a problem with the hull at all. Prior to it’s introduction a highly experienced racer took a pre-production hull and ran it at a SAW event that both Tony and I attended. He ran over 67 mph through the traps and the only mod was screwing on a huge prop. Since then folks have been obsessed with making it go faster than it was designed to go. Tuning secrets like CG and strut adjustment, along with limited run time, were ignored and there were many folks who were disappointed with the boat - through no fault of its own. If the UL-1 is to be run well past it’s design speed then hull mods will likely be necessary.


.

[NativePaul]

I've got it turned back as far as it will go...it is still lifting the boat.

So make it go back further, the bend/curve acts like a hydrofoil and if the front of the bend is higher than the back it will give lift in a straight line, and if the back is higher than the front it will give downforce in a straight line.

The only other alternative is that it is not going in a straight line, but turning left, which will also make it ride up the turn fin. Is your rudder set straight? Is the strut straight from left to right? If not you could be crabbing sideways whilst tracking a straight course.

[properchopper]

From the Vault (referring to the day Jay mentioned) :

DSC00820.JPG

[InspGadgt]

So make it go back further, the bend/curve acts like a hydrofoil and if the front of the bend is higher than the back it will give lift in a straight line, and if the back is higher than the front it will give downforce in a straight line.

The only other alternative is that it is not going in a straight line, but turning left, which will also make it ride up the turn fin. Is your rudder set straight? Is the strut straight from left to right? If not you could be crabbing sideways whilst tracking a straight course.

Boat is trimmed to run straight so the rudder should be set straight. Strut looks fine other than it is missing the bushing that it is supposed to have. The turn fin is actually angled down slightly...back is higher than front on the big bend line.

[InspGadgt]

you did this to decrease the angle of the sponsons ----- yes


to eliminate the step in the sponsons. ----- NO

Interesting...so our running area is not as smooth as yours is in the video. Will a lower sponson angle help in rougher water?

[properchopper]

Interesting...so our running area is not as smooth as yours is in the video. Will a lower sponson angle help in rougher water?

most likely. If it tames down the tap dancing in smooth water it should have a similar effect in "rougher water". I don't run hydros in rough water fwiw.

[InspGadgt]

most likely. If it tames down the tap dancing in smooth water it should have a similar effect in "rougher water". I don't run hydros in rough water fwiw.

I wouldn't if I had a choice :) We only have 1 fresh water source on the island and that's too small for these speeds. The alternatives are both brackish water and it would probably be more classified as a river than a lake.

I ordered the Hug airfoil from OSE so I'll be giving that a try first. After that I'll be working on an air dam similar to you and possibly the sponsons as well.

[InspGadgt]

So here's my strut with stuffing tube...as you can see I have no prop bushing. The stuffing tube just goes all the way through my strut. If I had a proper strut I could use some prop angle adjustment to help calm down the hopping. I'm hoping customer service will replace it with a proper strut but with them in the middle of a transition to Horizon, things have been moving a little slow.

[MADRCER]

So here's my strut with stuffing tube...as you can see I have no prop bushing. The stuffing tube just goes all the way through my strut. If I had a proper strut I could use some prop angle adjustment to help calm down the hopping. I'm hoping customer service will replace it with a proper strut but with them in the middle of a transition to Horizon, things have been moving a little slow.

You can see the bushing in the picture. It's in the stuffing tube....Nothing wrong with that. Pull it out, free it up so it floats inside and trim the tube a little then let her rip. Order another one if you have the old style because the new style has larger holes for better lubrication.
https://www.offshoreelectrics.com/pr...od=dh-aqub8003

[InspGadgt]

I'm not sure that's the bushing...my understanding was the bushing was supposed to come up to but not connect with the stuffing tube. If that is it...it's pretty stuck on...i don't think i'll be able to free it up. But when I looked at it it just looked like 1 piece with a ring grooved in.

[MADRCER]

I'm not sure that's the bushing...my understanding was the bushing was supposed to come up to but not connect with the stuffing tube. If that is it...it's pretty stuck on...i don't think i'll be able to free it up. But when I looked at it it just looked like 1 piece with a ring grooved in.

I'm sure it's stuck because most are just crammed in there. It'll come out just work with it. Throw it away and get the new version.

[InspGadgt]

The new version?

[InspGadgt]

I don't know...it is really tight and the thickness of the tube wall is the same as the other end. If it is...it is really stuck in there...I don't think it is coming out.

[properchopper]

So here's my strut with stuffing tube...as you can see I have no prop bushing. The stuffing tube just goes all the way through my strut. If I had a proper strut I could use some prop angle adjustment to help calm down the hopping. I'm hoping customer service will replace it with a proper strut but with them in the middle of a transition to Horizon, things have been moving a little slow.

Mr. InspGadgt,

This may not sit well but because you need some truth therapy I'll give the best of my knowledge and experience to get you some actual workable solutions -

#1 - You DO have a prop bushing. It's inserted into the end of your stuffing tube. This is standard operating procedure for about 80% or more of all rc boats - particularly those in the IC realm. The alternative is to replace the brass sleeve bushing with lead teflon bushings. They need more frequent replacement so the RtR boats often don't come with them.

#2 - it seems (from your picture) that your stuffing tube is pinched at the point it would enter the strut. This may be capturing your brass bushing making it hard to remove. Get it OUT somehow. If it doesn't turn freely chuck up the back end in a drill, smear some toothpaste (for lapping compound) on it and pull the trigger. This should soon allow it to spin freely. Clean off toothpaste when done.

#3 - You DO have a proper strut - Asking Horizon to put on a "proper strut" to a model being sold successfully "as is" for the last ten years or so (thousands sold) may not get you the response you're looking for.......

#4 - A stuffing tube extending all the way through the strut is a very common way of how it's been done for eons. In fact you CAN adjust strut angle with a little pressure on the strut - it'll bend/flex the slight amount you may need for a minor adjustment.

BUT

#5 - Regardless of how you adjust height/ angle (a tad too much height/angle and you'll have the rear hopping up and down - (I know this with knowingness.) and you WON'T cure the front sponson "hospital hop". For more than stock performance ONLY reducing the sponson AoA will get this done. TrustMe ! Tacking on aero goodies might sound good but...

Realize that this is a hobby-grade model designed to perform "as delivered" and runs beautifully in smooth water with the supplied prop. Once you go for more performance or run it in bouncy water mods need to be done and expectations carefully thought out.

Enjoy

Tony

[InspGadgt]

Ok thanks. I've been trying some penetrating oil to try and get it to loosen up so far but no luck. It is so tight if I chuck it in a drill I think I would damage the stuffing tube too. I guess I'll try heating it next and see if I can get it to free up.

[properchopper]

Lapping the brass bushing with a drill comes AFTER it's removed and can be inserted reasonably easy. To get yours out if it's that tight you might heat the stuffing tube (put a wet rag around the tube where it enters the hull to prevent heat transfer damage) and grab the end in vice grips. You might need to sacrifice the end but a replacement brass bushing doesn't cost much.

OR much easier and will allow less stressful strut angle adjustment :

Cut stuffing tube so that only 1/4" or so enters the strut and press in one at the rear and one right after where the stuffing tube ends.

https://www.offshoreelectrics.com/pr...od=oct-oc6ltsb