Sharing some info and pictures of my tethered hydroplanes

[Ricky Neal]

Ricky,
Do you run mono hulls as well or is this strictly a hydro type thing ? any outboard classes ?
I think some of the steam powered engines would be cool to see a video of..

Being as the boats are more airplane than boat, it would appear that centrifugal force would play a huge part in the ultimate design keeping the prop planted in the water.
Is the bridle adjustable front to rear to account for any prop walk? or AoA ?

I know you said the club has different sized cable for different classes, but has there been any progress of using difference type of materials ( kevlar, polys, carbon fiber ) to cut down on air drag and weight ?

Also, on the center pole, is there a specialized bearing that the cable rides on ? again looking at drag etc...even as tiny as this might be, it could be the difference in setting a new record.

Thanks for sharing!! this is an interesting view into a part of our hobby not seen in the states !!
Keep it coming!

There are no mono classes but there are vintage hydro's and no outboard classes.

The steam models are very impressive, every part is hand made and the bigger steam class weighs 16 lbs and will do nearly 130 mph. They are flash steam engines made from scratch with all kinds of advanced tech, one of them even uses a titanium con rod!

there are some videos on youtube but they are not of great quality, here's a clip of one doing 122 mph though.



B1's are more plane than boat in my eyes but the other classes really are 3 point hydros, the bridles are not adjustable but centrifugal force keeps prop walk in check once they are up to speed. Though if the conditions are choppy things can get a bit hairy and they will dunk in, nose first or the back end will not plant so the prop is unable to work well. As for AoA, this is all in the build of the boat, we normally adjust skegs and modify other components to get the boat to plane correctly.

Regarding cables, tether hydros predate RC models and almost all other forms of model racing. I am a member of the Victoria Park model steam boat club where we still run tethered hydros to this day. This is the club where tethered hydro's started and the club celebrated its 116th year this year.

As a result of this long history, technology has evolved naturally and with cables, everything has been tested. For the best performance and safest option, it's a steel wire we have settled on. Apparently, years ago a Teraline line was used but as the boats got faster they stretched the line and would get close to the bank. We have almost zero stretching with the steel wires we use nowadays.

Here are some old pictures of our boat club in East London

This one is from 1909


I am not sure of the year the below picture was taken but it looks roughly around the same time. That is our clubhouse behind them and it's still there and used today.


The centre pole has a mechanism that has a rotary encoder with ball bearings, its fairly drag-free but as we are all competing against each other all using the same pole we all get a fair crack of beating any records.

 

[Ricky Neal]

If anyone is interested there is a lot more info on tethered hydros but also tethered cars on this site

http://www.onthewire.co.uk/

 

[Grimracer]

I have a production new in box tether boat.. NOPE.. nothing special BUT.. she is awesome none the less!

Grim

 

[bill.c.smiley]

WOW.. I am not of the opinion.. we RCers have little idea what we are doing...LOL.. kidding.. very good stuff!

Grim

 

[bill.c.smiley]

I have several tether boats I built and ran in the late ‘50’s and 60’s in Seattle and also a collection of props we ran. The boats are not real pretty and I want to restore them some day. I don’t know how to post pictures but will try to figure it out.
Tetherguy

 

[Brad Christy]

Ricky,

As far as the centrifugal force....

If the tank is at the same "height" as the fuel inlet in the carb, there is no force pushing the fuel toward the carb. By "height", I mean in relation to the direction of "gravity", which, in this case, would be centrifugal force. If the level of the fuel in the tank is even with the spraybar in the carb, with the line between the two perpendicular t the direction of gravity or centrifugal force, the fuel will not flow without pressure making it do so.

Are your tanks mounted so as to be on a shorter radius from the bridle pivot point?

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

 

[Brad Christy]

Ricky,

Tether Boat Event

Are you anywhere in here?

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

 

[Ricky Neal]

Ricky,

As far as the centrifugal force....

If the tank is at the same "height" as the fuel inlet in the carb, there is no force pushing the fuel toward the carb. By "height", I mean in relation to the direction of "gravity", which, in this case, would be centrifugal force. If the level of the fuel in the tank is even with the spraybar in the carb, with the line between the two perpendicular t the direction of gravity or centrifugal force, the fuel will not flow without pressure making it do so.

Are your tanks mounted so as to be on a shorter radius from the bridle pivot point?

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

I fear I may have not best explained the tank and fueling very well, no doubt due to the fact that I have just copied what others are doing without fully understanding the principles behind it.

These pictures should better explain

This is the tank out of my A3 but they are all designed in the same way



Also, see this very crude drawing I just did, apologies for the poor art skills



The vent and the pickup slightly overlap with the vent being above the pickup by about 1/8" and about 1/8" past the entry to the pickup

The crease in the side where the pickup is located is further away from the centre line meaning when the boat is running centrifugal force causes the fuel to pool around the pickup - Hopefully, that makes sense??

 

[Ricky Neal]

Ricky,

Tether Boat Event

Are you anywhere in here?

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

Ha, no that was before I was running tethered hydro's but the attendance at that event is probably 75% of all the tether boat competitors in the UK, since then a few more have sadly passed.

I am one of the youngest members at only 36 and one of the main reasons I posted this info on here is because sadly the sport is dying as we struggle to get any new young members into the hobby.

I hope that me posting this info here will at least garner some interest and maybe someone will decide to give it a go but failing that, at least I have managed to document some information on how these are made.

 

[mercguy]

When I started in RC in the early 70's I became friendly with a famous tether boat guy named Ed Kalfus. He had gotten into rc boats about that time and all his equipment was homemade including his own digital radio design. He had a younger apprentice by the name of Jim Allen who a lot of you know by his expertise. Both Ed and Jim were machinist by trade. I still have some of Ed's homemade props that he used on his tether boats.
Bill Hoch

 

[phill fields]

Ha, no that was before I was running tethered hydro's but the attendance at that event is probably 75% of all the tether boat competitors in the UK, since then a few more have sadly passed.

I am one of the youngest members at only 36 and one of the main reasons I posted this info on here is because sadly the sport is dying as we struggle to get any new young members into the hobby.

I hope that me posting this info here will at least garner some interest and maybe someone will decide to give it a go but failing that, at least I have managed to document some information on how these are made.

Hey Ricky really great info you’re sharing. I run hydros in the UK and Multi boats too.
Do you run at Kingsbury at all? We haven’t raced there for a few years but I think it’s back on our calendar next year again. I remember a couple of times in the past when the tethers were running when we were there, as well as the full size powerboats on the main lake.
Be good to see them again as I have far more appreciation for the engineering than when we saw them as kids.

Thanks

Phill

 

[Jerry Dunlap]

When I started in RC in the early 70's I became friendly with a famous tether boat guy named Ed Kalfus. He had gotten into rc boats about that time and all his equipment was homemade including his own digital radio design. He had a younger apprentice by the name of Jim Allen who a lot of you know by his expertise. Both Ed and Jim were machinist by trade. I still have some of Ed's homemade props that he used on his tether boats.
Bill Hoch

I saw Ed Kalfus run his hydroplane through the 1/16 mile trap at the 1967 IMPBA Internats at San Francisco. It was the first boat I saw go 50 mph. Seems like it was powered by a homemade 90 nitro engine.

JD

 

[ids987]

Hi Ricky, Great info, and great sharing of info. It’s good seeing you on here, and some representation of this area of the hobby. I’ve popped along with my son, to a couple of the Victoria Park events - attending under Norman’s wing. I think I may have seen you at the last one of last year; with (I think), your A1 boat. We were made very welcome, and enjoyed attending. I’d hoped to try out a couple of air screw powered tether boats (MDS 15 powered), which I bought from a friend, early this year. Hopefully in 2021 !!

 

[Ricky Neal]

Hey Ricky really great info you’re sharing. I run hydros in the UK and Multi boats too.
Do you run at Kingsbury at all? We haven’t raced there for a few years but I think it’s back on our calendar next year again. I remember a couple of times in the past when the tethers were running when we were there, as well as the full size powerboats on the main lake.
Be good to see them again as I have far more appreciation for the engineering than when we saw them as kids.

Thanks

Phill

Hi Phill,

Indeed we do run at Kingsbury. Im renewing my membership this week ironically.

I think we have 4 meets there in 2021. I will let you know the dates as soon as i do

 

[Ricky Neal]

Hi Ricky, Great info, and great sharing of info. It’s good seeing you on here, and some representation of this area of the hobby. I’ve popped along with my son, to a couple of the Victoria Park events - attending under Norman’s wing. I think I may have seen you at the last one of last year; with (I think), your A1 boat. We were made very welcome, and enjoyed attending. I’d hoped to try out a couple of air screw powered tether boats (MDS 15 powered), which I bought from a friend, early this year. Hopefully in 2021 !!

I was there and i think I remember you. I was running the A1, sadly we are not allowed to run the A3’s there as they go beyond the speed limit.

come aling next year and we can get your B1 going for sure

 

[mercguy]

I saw Ed Kalfus run his hydroplane through the 1/16 mile trap at the 1967 IMPBA Internats at San Francisco. It was the first boat I saw go 50 mph. Seems like it was powered by a homemade 90 nitro engine.

JD

Jerry
I understand Ed was one of the first to go over 100MPH in a tether boat. He was running that homemade .90 engine when I knew him. Side exhaust on both sides with two expansion pipes.
Bill

 

[AgafonovRoman]

Thanks, Ricky. I just want to mention what in early 90's, gladly, I saw only tether car in action and it was really cool. Never seen any tether boats but I had one earlier made in our club from 80's. I send this boat to Norman Lara two years ago just let this boat be closer to actual leaders in this category.

Here some interesting stories from a collector I've found not so far time ago.

 

[Marty Slater]

hay over on rcGroups the is some more on the old tethered hydroplanes
just wish i could get it over here

 

[Ricky Neal]

Thanks Roman,

I will see Norman before Christmas so I will ask to see the boat you mentioned.