Encouragement you techies

Niine months ago, a state of the art Footy had a highly curvaceous sheerline, a bowsprit, a bumpkin and somethng snaffled off a lamp-post as a backstay crane. In many ways they looked like something off an Enmmet cartoon.

Now the latest boats have much sleeker looking hulls and the latest rigs are far more space age than those of any other class - but retain that essential simplicity which is what Footys are all about.

Keep it up, people. Footys should be where people in other classes come to look for imaginative ideas that work - and it’s beginning to work that way. No longer plodding and ugly but where the action is.

Once again’ keep it up: I’m proud to be part of you.

i will second that!:zbeer:

It’s pretty much a requirement to go against the norm for the design & build of Footies, because as so people had thought long ago, “You can’t make a 12 inch hull sail” but WE know we can! Some peeople have come up with some of the more significant ideas ( Mr. McCormack,) and some have thunk up some other ideas. I think that anyone who is building a Footy has come up with something personally unordinary in order to finish a hull, or just to fit all the radio gear inside. How about that tiny bowsie for the vang strap? It’s just a little piece of plastic or wood, but getting those three holes in it, and threading the line through can be a challenge for some.


here’s some aerospce. decided to offer things in lah dee dah versions.
also, some new parts for mine, as well as other’s creations.
the rudder is 3gm inclding the many clearcoats.

and a bagged deck.

Nigel, Please can we have a ransom hung rudder. I keep liikig at your moouldings and working out whether I have the courage to desroy the rudder subframe and transom moun it as god intended.

but i don’t like them. :lol:
i’ll cook up a proto and send ya one.
i would like to have appendages as product, and having both rudder options would be good, i’m sure.:slight_smile:

ps, just noticed this emoticon:witch: bout time:devil3:

Any chance that the references to “waboats” could be dropped going forward? The above would make just as much sense if the reference had been dropped. Personally, I feel it is unfair to keep taking “jabs” at someone who cannot respond. As I recall, the hull design you reference was ot just his design alone when in fact almost all of the eraly FOOTIES sported a similar (cartoonish ?) design.

Whether it was the right thing to do to be banned is not the question. He is gone and so I feel that it should also send a message to the forum to drop the side-comments. As noted - removing the reference to “waboats” would not change the meaning you were trying to convey, but it certainly indicates the ability to keep bringing that series of topic/posts forward - especially when new readers were not involved.

I had my issues and disagreements with someone, but after the situation was “cleaned up” by moderators, I have tried my best not to “drop the name” into the r/c forums.

I think there should be families of fin and rudder sections and bulbs available. The 'vaguely sharpened piece of balsa’fin distreses me enormously. Design for a couple of standard keel sections using well-documented foil shapes is easy. Tyhe same applies to rudders.

I have proposed a system of modular bulbs elsewhere on the normal forums.Therse are based on the dynamic theories normally used in airliner fuselages so they should be reasonably right. They have the great advantage that bulbs can be produced to nearest gram accuracies without much craftwork or tooling by with manufaturer or skill by the builder.

the peice is not carved balsa, it is three peices of carbon laminated shapes, joined together to creat a whole.
the foil is an actual naca 0065 at just under 10%.

the future keel, and rudders will be similar. i think for the rudders, i’ll use the existing foil for both under, and transom, but the latter will just have a fourth section bonded to it, to be able to be used as a transom-hung jobbie.

if i do decide to add foils to the products, they will be long tapering blanks, that can be cut to suit what ever size project the person is building (to a point of course)

forgot to add that the freeship has a good selection of foil templates to choose from. good fer muckin about.

I didn’t think you were producing sharpened balsa - but a lot of people (like me) don’t have the skill to make much else!

An 0065v strikes me as a bit thin and easy to stall. Any views/

the original was shaped from balsa. it was then used to cast the composite version.

one thing about that wood, is it is great to work with

I’m not sure it can be NACA 0065, as to my understanding of 4 digit NACA series foils, this would yield a thickness equal to 65% of the chord dimension. This German website is able to give interactive images of foil sections:
It allows you to set any parameter values you chose & see what it looks like.
Then you can print it out to the correct scale & create templates for use in shaping the foil.

I would guess what Nigel is talking about is something closer to 6.5% which sounds entirely reasonable.


my foil lingo is probably way off.
it was a 65 type foil at about 10% thickness. if that sounds correct?
the number choices were 65-006, 65-007, etc. i chose the 65-010
i figured a little thicker due to the slower speeds.

someone mentioned a sears cnc fer cheap. if i could get that, i would like to make an assortment of foils to try out, but i poor, so hand-carving it is (dam arthritus).

Sorry people, misinterpretations all round. I interpreted it as a 6.5% thickness foil (doh - but very good lunch!).

I agree with Nigel that this is pobably a bit easy to stoils as something as titchy as a Footy. I tend to use 9 or 11% thickness raio and a modeerate aspect ratio. The theoretical figures don’t look all that good, but when you gestimate the rections of a real helmsman, they probaly pan out a great eal better. That’s also why I like rudders as far aft as possible - the slightly inept (i.e. most of us) can catch errors that little bit later before angles of attack have to get high. To call the mathemical 'models 'I have sketched out ‘calculaions’ or even ‘models’ is to be grossly flattering but I am fairly sure that the ‘effective get out’ angle of attack declines pretty quickly as the lever about the pivot centre (whaever that may be) increases.

An old mate of mine turned up at the sailing site yesterday (we were sailing IOM`s) his name is Dick Willard and he used to be a gun R/C Pylon racer.
Dick not only built his own engines but also the propellers to make these aeroplanes go very very fast. His depth of knowledge regarding airfoils, renolds numbers, tip vortices and all that kind of stuff is immense.

I had my FOOTY in the van (as you do, right) and he was facinated with the concept and even more so when I put it in the water and he saw how well it sailed.
The remark he made next is what I want to share with you.
Some here will be aware of the model fliers doing indoor aerobatics with electric powered models.

Have a look if you are unsure of what I write.
Any way, I am told that these amazing little aircraft dont have an aerofoil shape amongst them. It is all done with flat plates and blunt edges and clever stuff that I dont understand like “super stalling” wing tips and such.
The term for this low speed theory stuff is “Bumblebee Technology”
We all know that Bumblebees "cant possibly fly" and yet they do.
Dick did explain how, to me, but honestly I lost it after the first few minutes and would need to go round again and there is no way I would post here my basic mis/understanding of the theory.:bag:

The upshot of my ravings here is to report that my friend was off home to work out the renolds number for a 2inch chord at 2 ft/sec in water as he seemed to agree with my contention that the shape of the foil on a FOOTY makes no difference to the efficiency of said appendage.:propeller
More to follow shortly.

Ian this is most interesting.

Please could people read the Wikipaedia article on Bumblebees. Nobody ever said at all seriously that they could not fly. One likely bet seems to be a Swiss aerodynamacist as an after-dinner joke.

Having checked that deep stall and superatall are in fact the same thing, it does not seem likely to be relevant to bumblebees or Footys (although I suppose it could be to a boat with two offest rudders like an O-60). Deep stall occurs when stall of the main wing of a high-tailed aircraft (e.g. DC-9) puts the tail in the broad stalled wake of the wing so that the control surfaces on the tail become ineffectve. I somebody’s memorable phrase, ‘the aircraft comes down with al the locked-in stability of a runaway lift’.

It looks as if what Ian’s friend is talking about is dynamic stall. This is indeed highhly relevant to how oscillating-wing insects fly. However, caution should be excercised.

  1. At a very early stage of my involvement with Footys, I had the thought that maximum draft might indeed sufer from fin stall under quite moderate conditions. Practical experiments assissted by Graham MclAllister suggested this was unllikely to be the case, except possibly in very extreme conditions. It might, however, be sensible to increase the thicvkness ratio of the foil towards the tip.

In order to use dynamic stall, the foil must be stalled. This can off course be induced. It is quite possible that My/Graham’s bathtub experimentation/prinitive analysis is wrong. Is anyone prepared to build a small flume tank and see what actually happens? And peferably share the results. One thing I am cetain of is that if the corect answer is foils that operate partly in normal mode and partly in dynamic stalled mode, their design is quite definitely not a job for the cub scout!

  1. Remember that not all insects use oscillating wings to provide lift. Beetles use conventional hard wings for lift and oscillating wings for propulsion - or that is how I understand it.