Hey guys!! I'm a big fan of float flying, along with other aspects of the hobby. A few years back, I bought a Laker from Balsa USA, and since I built it and finished it, I've hand nothing but a hard time getting it off the water. I've even went as far as mod'ing the hull to a V-bottom. And even still, it does NOT want to come off the water. Once it comes off the water, it is a pleasure and a joy to fly. I probably have only 30 flights on this plane, and it is discouraging. I was so disgusted with it, outside of flying characteristics, I went to the Toledo Expo in 2000, loaded with both barrels to Balsa USA. The guy who we talked to, said that "his" has no problems coming off the water. Told him what we did to try to improve it, and it just stayed the same. He was completely sold on "his" airplane has/had NONE of the afore mentioned characteristics.

What I have for power. I have a Rossi 40, and the noisy muffler, which wakes everyone up on the housebaot trips!! I have a Q500 racing motor backplate mount, so I have the engine mounted sideways, saving a small amount of weight. I also have about 3 degrees of UP thrust in the engine. Was built per plans, but while on a trip, we added 3 washers behind to bottom side of the mount. I also mod'ed the hatch, allowing for a larger prop diameter. I think I am running an 11x5 APC?? It just flat out hauls the mail!! We all fly at Lake Cumberland, out of Conley Bottom. It's a blast flying from the runabout boat!! I have some VHS video of 4 planes flying from a 17' boat. 4 pilots, 1 driver, and 1 camera man. Talk about a blast!! It was!!!

If you all can help me out, I'd be most appreciative!! I'd like to go float flying atleast onced this next year!!

Thanks!!

Chris~

I have seen several Lakers flying, and they were all very well-mannered. None had any problem getting airborne.

I don't think the original hull design or your v-bottom modification would have any problem breaking suction. Model planes don't seem to have a problem with that, anyway.

It would seem that you either have a technique problem, or something unique to your plane.

Technique: Use FULL UP elevator to taxi, and when you initially start your takeoff run. As soon as it pops up on the step, neutralize the elevator, let the plane gain speed, then gently apply back pressure to lift the plane off the water.

How did you install your water rudder? Is it oversized? Can it kick up? If the water rudder sticks into the water more than 1/2" when you taxi, it is too big unless it retracts or kicks up. Water rudders are for taxiing. ONLY. If it is in the water when the plane is on step, it can keep you from reaching takeoff speed. If it dips in the water when you rotate for takeoff, it can push the nose back down.

If your plane is too heavy, it could be submarining when you first apply power. When you first start to accelerate, some of the water is pushed forward. If this comes back over the nose, it causes drag, loss of hull lift , and loss of engine thrust when it slows down the prop. The cure for this, if it's not too severe, is to add chines(spray rails) to the edges of your hull. Make them from triangle stock. They provide more lift by deflecting the horizontally-flowing water down. This reaction force lifts the hull and helps you pop up on step. They also help keep spray out of your prop.

IFLY3W

Jim Casey sounds like he is on the right track. I have not even seen a Laker in person but I have heard that adding spray rails is a must for the Laker.

Hay IFLY,

Check the wing incidence. Sounds like it needs to be more positive in relation to the hull centerline.

Cheers,

CR

I had a friend with a Laker that also had a hard time getting it off the water. While I love Laddie's designs, I always swear he must only float fly on perfectly calm days. The step on his designs is very short so the aft end tends to continue to get splashed which keeps it from getting up to speed and on step in anything but very calm water. Spray rails from the nose block all the way to even with the step tend to help this by adding more lift and keeping the water off the sides. Adding a vee bottom would actually make this situation worse because they tend to stick more than flat bottoms. The other possibility is to "add" to the bottom to make the step higher. You could try this easily by adding a piece of one inch foam to the bottom from the step forward. Sand it to blend to the front and cover and secure with packing tape. I never got a chance to try it but bet it would do the trick. You want about a three degree slope in front of the step compared to the wing centerline.

The other problem with the early Laker was the tail would get stuck in the waves too. The latest re-design gets the tail a bit up off the fuse. If yours is the older one, you need to raise it.

Hope this helps.

I could not get my Laker off the water, because every time I developed sufficient speed to take off, one of the wing floats would dip, drag, and cause a waterloop. I solved that problem by gluing thin plywood ski-like extensions to the bottom of the floats, making the bottom of the float 3 inches longer. They are the same width as the wing floats, and the same color, so they are inconspicuous. Now it is very easy to take off, with smooth or rough water. I think the plan is excellent, and would not recommend changing the wing incidence. Mine is fairly light, and a floater. It will do rolls, but they are slow and graceful. I used flaperons, and it will hover in a 15-knot breeze.

I agree Jim Casey knows how to get a seaplane off the water. Don't know where you are located (altitude makes a big difference), but I'd look at adding a little power. A strong 40 is the low end of the engine range recommended for the Laker. An OS 46 FX would probably solve any problems you have in getting the Laker up and off the water.

I IFLY/W,
Float are particular on water and have a unique incombrance that is unique to them - the step. In principle taking off on water is no more difficult than from grass except for one thing - the step. Once the plane begins to move on the surface of the waster it eventually climbs on the step and them it simply wants to stay there. This phenomenon occurs as the air pocket formed in the crest of the step causes a certain vacuum effect holding the plane there. Only increased up elevator will unhook it from there...increased speed that will cause additional lift with expected results.
I have a Laker powered with an OS .60 ( older type) and it handles it perfectly. Remember the Laker is over 70" span and a .60 is not too much for this type of plane. Try this if it is within your means and see the results.
Good luck.
John

Laddie Mikulasko designed the Laker for a .40 - .46 engine. While it has a 70" WS, it's design weight is only 6.5lbs all-up, dry. It doesn't need a .60 to get off the water. It's a common myth that a float model needs more power than the land version. It just isn't true unless the land version is grossly underpowered to begin with. I have added floats to and flown several land models and flown them off water with the same engine as I used for land operation.

What is really critical is setting the wing incidence relative to the float CL at the right angle and positioning the step at or near the model's original CG.

For a flat-bottom wing, like the Laker's, as I recall, the incidence of the wing to the hull CL probably needs to be at least 3 degrees positive. I'll bet 5 wouldn't be too much.

I built a Balsa USA Stingray, exactly according to the plans, that didn't want to get off the ground. It would tear down the runway with the tail up but wouldn't lift off until I pulled a bunch of up elevator. I increased the incidence of the wing and it got off beautifully after that.

Could be the same with this Laker.

Cheers,

CR

Charley, you are right in what you are saying...if taking off was the only thing about flying off water. Mikulasko built airplanes way back then when the biggest engine you saw at the field was a .60 size. Very few had larger things then. The .40 size was most popular. I remember A & A Industries built 1/4 scale planes powered by .60's. They flew but how boring by today's standards. Flying was economical and taking off was great fun along with landing. 3 degrees of positive incidence will certainly affect the flying character of the once the lift off is done. Add engine and it will want to climb, climb and climb even more. Reduce trottle to stop lift and this thing will want to drop...unless you trim for level flight down/up elevator as the case may be. The 3 degree positive incidence on the wing would be acceptable if it is at 0 degree differential with the horizonal stab.
Ok! I'll give in a bit. A .60 may be a slight bit more that essentially needed. However, I still feel that it will require a good .50 +. The Laker has a lot of plywood in it.
Have fun
John

John,

All flat bottom wing planes want to climb as more power is applied and airspeed increases. The answer to that is down thrust, down trim or positive incidence in the stab to hold the nose down. In other words, decalage and thrust line will take care of the flight trim.

Note that the angles I stated are in relation to the hull CL on a flying boat or the float CL on a float plane. The flight trim is a different ballgame. The idea is to get the model "on the step" and planing on top of the water. A semi or symmetrical wing takes even more incidence angle
than a flat-bottom relative to the floats. The model needs lift from the wing to get on the step.
All of this is can be found on several web sites and books on rigging a float plane. I got the basics from reading Chuck Cunningham, a recognised authority on float flying.

BTW, in my experience, it's easier to get a float plane off of slightly choppy water than off of mirror smooth water. The full-scale guys sometimes taxi in circles to get the wave action going before takeing off.

You and other posters on this thread have made some excellent points. I'm just suggesting that if all else fails, it's easy enough to shim the wing up a bit and try it.

Cheers,

CR

No flat bottom wing will fly without positive incidence? Really?
Why is that?

Hey guys!
we have something going here that is away from the initial question...but is getting instructive.
Bernouilli's theory is that a flat bottom wing moving forward on a straight and level plane will naturally lift simply because of its upper wing curvature.
Have fun experimenting with this great hobby.
John

OOPs, had a brain fart on the flat bottom wing bit there. Or was that a "senior moment?

Sorry folks,

CR

Thanks for all the info guys!! All of it is well worth a little bickering and changing subjects!! Just kidding!!

This spring, providing school and work is going well, I'm going to remove some monokote from my hull and add some spray rails and do a second look at my V bottom hull design.

Someone made mention of a V bottom actually keeping the airplane on the water moreso than a flat bottom?? No, I don't think so. We, Dave and I did a V bottom mod at the lake in roughly 30 minutes to possibly change some of the characteristics of my plane. The V bottom from the Flat bottom actually helped, some, but not quite enough to make me completely happy.Look at Dave Thacker's web site www.radicalrc.com and if I recall correctly, there is a header there for floats. If so, check that out. I have flown land planes with V bottom floats on them, and had HUGE success. Have flown his own design, based off the Laker, but HE did alot of mod'ing to it, including a twin step V bottom hull. Really cool design. Flown off the water, without the tendancies that I described as my plane had. I was stumped heavily until I started to surf this forum.

Thanks again guys!!!

Chris~

Chris,
I agree that the V-bottom has superior handling.

On takeoff, it deflects more water to the side. Flatbottom floats initially push a bow wave in front of the float. Sometimes this comes over the nose and gets into the prop, before the airplane gets up onto the step. This is reduced with v-bottom floats. Spray rails deflect the sideways flow downward, giving more lift.

On landing, the v-bottom cushions the initial contact because it meets the water first as a point. I can't get a seaplane with a flat-bottom hull to "grease" onto the water surface. Even a really good landing will have a skip or 2. With a v-bottom, there are no gaps in the wake. The water doesn't lie.

Also, with a v-bottom, the plane is less likely to slide sideways on the runout after splashdown. Seamasers, sea cruisers, Lakers will all go nearly sideways if you hit rudder after touchdown. This is cute until you hook a tip float.


I just designed my own seaplane, and after initially having a flat-bottom hull I changed to a v-bottom hull. As my Dad used to like to say for emphasis, "It is lots more betterer!"

Pic attached. I have extended the spray rails all the way to the nose, and it made a big difference.

Jim, EMial me some more pics of your design. I like how you integrated teh splash rail, or whatI think they are in the hull.

My email address is [email protected]

Thanks Jim.

Chris~

Here's another pic.

and one more