LADDIE

If changes Jim is suggesting do not help I would do this. Increase the buoyancy of the hull and add the step. You can do it easily using the foam block. Sand the block so it follows the contour of hull bottom up to the step. The step should be 1” high. Sand the block so the front tapers to nothing. This will give you steeper angle of the bottom which when moving forward should force the nose out of the water. Place the step under the C/G. Attach the foam to the bottom to the hull with double sided tape. If this does not work, you will be able to remove the foam easily.
Good luck.
Laddie Mikulasko.

dieFluggeister

All very good ideas guys, thank you. I will experiment with her late this afternoon and try some of these. It seems like it has plenty of power, but no amount of gentle hand can easily get it up on step. I have to use brute force to get though the wall of spray and that just sounds horrible! I am not going to try to test fly until I get this transition thing figured out more.

Here is a pic i took yesterday. Sure does look purdy! I did some reading in Lennon's aerodynamics book and he talks about this plane a little. One thing sort of peculiar to this plane is that by having tailbooms, these ride outside the wake trough created by the fuse pod. Therefore they don't sink lower and allow the nose to pitch up until the aircraft is up on hydrodynamic plane. (and as Lennon calculated, has the airspeed to fly) Apparently, this is why he designed the hull so narrow and deep. This gives the required 9 degree angle between the fuse pod step and the end of the tail boom - just the AOA needed for takeoff.

Anywho, I'll work with it today and keep you posted of my progress. Thanks all for your help.

scale only 4 me

My Feedback: (158)

I'd add some clear plastic spray strips at the bottom corners of the fuse boom, essentially making the fuse pod wider
What you have there it's not going to do much to help it up on step

good luck

Lnewqban

Returning to the original 7" propeller will reduce the area of prop exposed to water splash a good 24% (7^2 / 8^2).

Play with the thrust angle, so you keep the same arm respect to the CG, hence keeping the originally calculated nose down pitch introduced by the thrust.
That additional 1/2" pylon plus a powerful motor (higher thrust force) may be pushing the nose down too much at the same time that they rise the tail up, which is the opposite to what is needed for good water take off.

lupy

My Feedback: (3)

I third!, spray rails are definetly a good idea. Water will just wrap around that fuse, and get into the prop. Esp since it's so far back.

As far as prop incidence, Since the prop is behind the CG, then traditional ideas about up / down thrust get pretty tricky.
If you tip the motor so that the prop points down towards the tail, that will tend to unweight, or lift the rear of the plane. It will also tend to tip the plane nose down because the lift is behind the CG
If you tip the motor so that the prop points up towards the tail, then there is some townward thrust that will make the plane sit lower in the water, but since the push is behind the CG, the thrust will also tend to tip the nose up, possibly helping you. As you can see, The lifting & tipping forces tend to cancel each other out, as opposed to having the motor in front of the CG, where the tiping / lifting forces add together.

The Upshot of all this is that I would try spray rails first. If that dosn't work, do a quicky mounting plate to drop the motor a little, and try the smaller prop. The reduced thrust hight will definetly help your nose down problem. Electric Motors tend to like big props to make lots of static thrust, but often more thrust isn't really what is needed to get on step.

If all else fails, flipping the pod and putting the motor in the front would sure make everything a lot easier. A lot of designers, esp in RC tend to start with a sketch of what looks cool, and then work to make it fly, Efficency and good aerodynamics often have very little to do with the end result, as evidenced by the flying lawnmowers, cars, hydroplanes, witches ..... We have the advantage of big relitivly cheap powerplants, with thrust to weight ratios that most real pilots only dream of. Aditionally, because of printing deadlines, a lot of designs got published before the designer had time to iron out all the quirks, and now we are left with designs that arn't really the best end result.

dieFluggeister

Well I have been working out some of these issues but I have not had a lot of time. Here is what I have so far....

The shape of the chines on the bottom of the main hull were not very aggressive according to plan. I mounted some plastic strips to extend the outer spray rail and in addition it gave a larger planing surface to get it up on step.

In addition I mounted the motor with 3 degrees up thrust.

The combination of the two got the plane up on step fairly quickly with only a brief spray problem as it transitioned. I think I will extend these forward about another two inches and it will virtually eliminate the problem for the short term. A long term fix will be a redesign of the bottom making the last chine sharper and at more of a downward angle.

I did push it further and briefly took to the air. I did not make an attempt to do any flight testing at this time.

One frustrating problem I am encountering is water entering around the flaps and saturating the wood. There is about three miles of seams in the monokote around the flaps and ailerons and it is proving difficult to keep everything dry. So she is retaining a little water weight today! I am going to let it dry tonight and try again tomorrow.

dieFluggeister

I extended the plastic spray rails on the main hull from the nose all the way to the leading edge of the wing. As a result it easily lifted out of the water with no spray whatsoever hitting the prop. Problem solved.

However, I tried using the rudder to turn on one of my high speed taxi runs and it dipped an outrigger and cartwheeled. No serious damage, just broke one of the flaps.

Two steps forward, one step back....[]

dieFluggeister

After getting the water handling ironed out and one short flight, I am sorry to say that I was about one step away from dedicating it to that big scrapyard in the sky!

It has been gaining weight-obviously from water AND I have had the really odd problem of the control surfaces getting way out of adjustment every time I took it out. Well the water intrusion was no surprise, the design leaves many places where water can get in despite my best attempts to seal them. So I took my trusty #11 and opened up the sides of the booms and was greeted with mildew! But to my surprise I did see that the Gold-n-Rod control wire sheaths were all bent out of shape?? Apparently the wet conditions made the sheaths expand and threw all the tail group control surfaces off! I did an experiment by placing one in water overnight and it expanded from 30mm to 35mm in just a few hours. Whats more the diameter also increased causing a lot of slop for the wire.

So, a lot of disappointments in this particular design from a standpoint of sealing the water out and the complexity of the build (#of parts). A few suggestions to those who would take a stab at this one:

1. Modify the flaps so the torque rod runs through the entire length of the flaps. This will give it more stability.
2. Where the flap torque rod exits the sides of the booms and main pod, coat the rod with wax (chapstick) and seal the whole area with rubberized caulk. This makes a decent gasket but still allows the torque rod to function. I discovered this one too late.
3. Change the bottom of the main pod to more aggressively deflect the spray for water takeoffs.
4. Change the way Gold-n-Rod flexible control wires are used. Possibly substitute metal or CF pushrods for as much as you can.

For right now I think I will shelf this project and let it dry out. Possibly take it out this winter.

scale only 4 me

My Feedback: (158)

I''ve never heard of water causing the plastic to expand, temperature difference yes, but water??
I've used those wire/nyrod in water planes many times and never experienced what you described

BTW,, a tip for the nyrod set up, I use blue waterproof bearing grease in the housing to seal where it exits, that will stop water from entering the nyrod housing,

IMHO,
Monokote and water planes just don't mix, You give up weight but nothing is better for waterproofing a seaplane than Glassing and Painting. Especially components that make direct contact with the water like the floats or flying boat hulls.

Looks like you have the spray problem solved,, go for it.