AJ1202

Hi I posted here once before, this was before I had any idea what I was doing when it came to seaplanes. I still don't know much but have been trying to research as much as I can. Quick history first, I have been flying for going on 3 years now and have scratch built a few planes from plans and a couple of my own designs, some succesfull some not, I feel confident in my building skills now but need help and advise when it comes to a seaplane. I don't want to take a plane and add floats, I want to build a true seaplane. What I want to build is a plane that I'm going to design after the aerocat amphibian, I have some basic drawings but haven't got the sizes or scale sorted out yet. I should have that figured out very soon and that's where the need for help begins. I have a lot of questions but will try to keep them in line with each step of the build, so for the drawings I would like to ask, for the float/fuse section would a semi V or flat bottom work better on a twin boom set up, I have pics of the floats on the real plane and they appear to be semi V all the way to the step, is the semi V more stable than a flat bottom and which type gets up on step easier. Thanks for any advise and help on this build

AJ1202

Well I have already hit my first snag, can someone point me in the right direction for a set of plans for a float that is around 30 to 35" long that I can adapt into the float/fuse. I want to build everything on this one, I can't seem to find a good set of plans for floats that big
I'm afraid if I try to just draw them with my limited experience it will turn out like my last failed attempt.

T_om

Here are a couple of links:

http://www.geistware.com/rcmodeling/...oats/index.htm

Some simple stuff you can size to your needs:

http://www.rcgroups.com/forums/showthread.php?t=195067

Some free float plans:

http://www.flyelectric.ukgateway.net/floats.htm

One more:

http://www.flyinglindy.homestead.com/skisandfloats.html

That should keep you occupied for a while.

Tom

AJ1202

Thanks Tom, I had just found a link with some good plans and downloaded but I'm going to look through these to see if I find something better suited. The plans I down loaded were for flat bottom floats and just a little smaller than I wanted and I realy wanted V or semi V design, I figured as long as I get the float and step right I can adjust the fuse part to fit. On the plane I'm working on would the rule of step being about 2" behind CG still apply, once I get the templates drawn out I'm going to use a program to get CG before I start building the float/fuse. Also for a 32" WS est AUW of 30 oz would 3" wide floats be enough to make it stable in the water.
One more, would a 1" step be about right

Newc

I suggest that you conduct a search for articles written by Chuck Cunningham. He has written what many of us consider to be the definitive articles regarding the planning of floats including length, amount in the front and back, location of step relative to CG, etc. I have used his articles to make a number of very nice - and really excellent performing - floats for various size planes. My construction method has been white foam sheeted with balsa after the hardwood spine was installed into the groove for it on top.

As you will find in Chuck's articles, this is NOT the right 'rule'. Proper step location is 1/2" behind the CG. And there's a lot of detailed information about how the proper step is made.

AJ1202

NewC, got it, Chuck Cunningham, I think I read some of his articles when I was trying my first build, I will revisit the this, I meant 1/2" that was typo. It seems all the float plans including the ones Tom linked are flat bottom without any reccesions to help get any air under the float from nose to step, does it make that much difference to have these grooves I'll call it, or does the flat bottom work fine. Thanks guys and be patient with me I'm learning and I realy want to have a seaplane in my hanger to fly

Newc

I don't like flat bottom on either floats or boats. I always use V bottom boats and floats for the same reasons - ability to handle a slight chop or heavy waves and directional stability. You will also notice that full scale float planes have either V hull floats or the hulls of true flying boats are V hulls. This isn't to say that flat bottoms don't work, as the Northstar has a flat bottom center hull and sponsons. See the attached photos for some of my examples, including the bottom of one of my Northstars and the crude but very successful flat bottomed floats on one of my brother's planes (the pink one!)...

AJ1202

Thanks for the pics, I think I have something to work with now to make my initial templates from, I just have to work out the length and width the draw them out. I'll post some pics of the templates when I get them done and ask if they look like they will work, I'm going for a V design on the floats as I want the best stability I can get and help in lift once it's on step. I think I'm going to go with 3" wide floats

JimCasey

My Feedback: (1)

3" wide is not enough for a 35" float, unless you have an exceptionally light plane on two of 'em. 4" minimum for dual floats that long.

That's the big problem with the Herr Aquawhatever--the hull is too narrow, there is not enough lift in the fore hull, and it submerges when power is applied. Blub.

AJ1202

Jim, Thank you for the heads up on that, OK 3" is out, I am thinking I'll be looking at close to 28 oz once it's all done, I am expecting the float/fuse to be around 35" in length but the actual floats would most likely only be 16" then they will rise for the tail section, would 4" work with this set up or should I look more toward 5 or 6" I plan to try to draw out the templates tomorrow, I'll post once done once I have something to work with I can change it as needed untill I get a good working template to start the build from

Newc

I'd follow Chuck Cunningham's sizes just as he has published them. They work that way. You did look up his articles and specs, didn't you?

In the event that you didn't look up the article I have mentioned, here's photos of the diagrams that ought to help (and they may also be of benefit to others as well) with your design and building of the floats for your particular plane.

AJ1202

Yes I have, Maybe I'm just looking at this all wrong still, here is a link of what I'm trying to build http://www.creativeflight.com/gallery1.htm
I can follow the build for the floats but I still have to factor in the fuse and tail

cyclops2

Just to give you some idea how important V bottoms and the step on them can be.

80' WW II Elco PTB had 5 steps built in to the planning bottom that is wet at top speed.

Speed jumped from 40 knots to 55 knots. They changed NOTHING else to maximize improvements.

The V and WHERE the step is, can take a DOG, to a lover.

I use scale plans and enlarge them at Staples . Cheap and accurate.

Do not get side tracked and wrapped up in design. Copy a proven plane in RC modeling.

I have a 62" blue foam Martin China Clipper. From the AMA plans section. Hand toss a perfect glide for 30' to 40' everytime.

That plane HAS WING AREA.
4--speed 400's.

AJ1202

I think that's what I have been doing, reading too much intot he fact that the floats and fuse are one in the same, but actually the floats are the floats and that is that, it just so happens the fuse is molded into them, I like the idea of letting staples size the plans, never thought of that. Cool
I think once I get past this step, no pun intended, everything else should just start coming together

Newc

At the risk of offending you and your sensibilities, you still don't seem to be willing to look at what an expert - Chuck Cunningham -shows as the optimum sizes and locations of the floats. If you looked at the drawings that have been provided you would see that your concerns as expressed following are well handled.

Your comment is a bit ambiguous, in that one must consider strongly the plane for which the floats are being designed and built.

AJ1202

Not to worry about offending me, well almost , I am lost here and trying to cram alot of info at once, I see your point, I'm just getting confussed, I'm going to go read some more articles and try to get a better grip on all this and print out the pics you posted and use them to see what it is I'm missing here. I know I'm prob making this harder than it has to be. Maybe it would be wiser for me to get a set of floats for one of my planes I have now and start learning from there, I definatly have respect for you guys that build and fly seaplanes or even just off water on floats, no offence meant by the last part of that statement, I'm finding there is no JUST when you fly off and onto water
Let me do some more research and revisit this in another week or 2
Thanks for all the input so far. I'll reopen this thread when I'm ready to start this build up again
because I still want to build a seaplane.
Thanks again

AJ1202

Well after much reading and looking at many planes with floats and actual boat planes I have now built my plane and will get the floats for it tomorrow, now I have it all measured out for the float placement but have one question. Would it be advisible to use the rods between the floats to support side movement, I'm guessing since this is a twin boom design it will act just like a set of floats on LG and flex if not held fast by the connecting rod. Here are a couple pics of the build so far. Now I still have to mount the servo's and then seal in the booms and of course mount the motor or motors, haven't decided that one yet, they are gonig to sit on a fairing type pedistal on the TE of the wing.

Airboatflyingship

Aviation..great site quite a few waterplanes and..Aerocat dont miss this one..so different it might be Russian
http://ensign.ftlcomm.com/access/to...n/AViation.html
http://ensign.ftlcomm.com/planes/aerocat/aerocat.html
http://www.creativeflight.com/

Tryv Aerocats layouts

AJ1202

Well I got the floats installed, I would appriciate some comments here if there is something that looks wrong or that is not going to work, now would be a good time to point it out. I still have a long way to go with this build but I feel it's going pretty good so far

simhatus

Hi

I want one. I think it ought to fly providing you get the engines set up right.

I'm guessing they will need a little downthrust.

The floats are a tad close together might tip over easily in anything but calmish conditions.


Simon

AJ1202

I was thinking the same thing at first but it is exactly the distance apart for the plane, in other words the floats are designed for this plane when in it's original form and using the LG and side supports they are exactly where they would be, I think my changing the design throws the perception off or something, at least I hope that's what it is.

simhatus

Hi

I realise its scale and you shouldn't alter it.

What i really ment is unless you have a lot of calm weather you might need somthing else on floats as well.

Simon

JimCasey

My Feedback: (1)

AJ: Where is (are) the motor(s) to be installed? If it's a pusher on the CL, you'll probably want internal spray rails on the floats.

Upthrust (Pusher motor pointed down) is usually appropriate in a seaplane because of the high thrustline. Helps keep the thrust from pushing the nose down.

AJ1202

Simon, oh OK I see what your saying

Jim, I plan on putting 2 motors on the TE of the wing just over each boom, I'm going with BP21 and 6X4 pusher props,I am building a fairing type pedistal exacly like on the real one to mount the motors on, if you look at the aerocat in the links you can see what I'm shooting for with this one. Would you mind looking and let me know if I would need spray rails and if so just point me to where I can research how to make them. I'm at a stage where if I need to change or add something I need to do it now
Thanks

JimCasey

My Feedback: (1)

If you are putting props >there<, the only way they can get wet is if the plane flips over. You probably will still need some up thrust.