Tomcat

With respect Crash, I think that's a very bad idea!

Klippy
A bit puzzled.
Exactly what is a bad idea?
Flying the Tomcat? Giving it only one more chance? Using the stab?

Klippy. Normally I would agree with you, but whilst doing the reset I did find what could possibly account for the sudden erratic behaviour. Most of the setup on the stab is controlled by dip switches, for wing type, dual ailerons, servo reversing ect. Switch 6, if set to on is dual aileron, if off it's aux 1. This was my flap channel. When I went through all the switches to check them it felt as if it wasn't fully clicked to the off position. If it did momentarily bleed over the left flap would be coupled to the ailerons ! :ohmy: The other reason I am prepared to give it another try is that initially I only had the default fail-safe set, which just cuts the motor on loss of signal. I now have it set to return all control surfaces to neutral as well. Plus of course I will be better prepared for the unexpected, at the first sign of trouble I will just make sure the gyro is off. It would be a shame to throw £35 worth of RX in the bin without a fair test, or maybe I'm just tight ! :whistle:
Just seen your comment Q. I'm pretty sure he means the stab.

Sorry Crash, it was a very quick response made in haste. Having a 're-try' without any knowledge as to why it crashed is never a good idea. However from your post it's obvious that you think you've found a potential problem, and you've set adequate fail safes. There's no reason in my mind not to try again.

Now that I know the Tomcat fly's & has plenty of power, I thought I would build some floats. Seems like a good idea as we have a nice little lake at the new site. :woohoo: The model is well suited as all the electrics are in the top & sealed off from the bottom. I am using 3 mm foam with a couple of box sections in 6 mm to accommodate the carbon fibre booms. The two wood planks will be used to screw & glue the undercarriage, which I will make in wire, unless anyone has a better idea? All the dimensions are from a "float calculator" I found on-line. They are bigger than I thought !
I got this far & ran out of glue sticks. :pinch:

What are you going to use for steering? I must say I've always been surprised at how big floats must be.

your gonna need a water rudder crash.

crash
Are the undersides of the floats flat?
It is normal to use a V bottom as this gives a smoother transition as the plane transfers from hydrodynamic lift to aerodynamic and the same on landing or put another way it gives a degree of 'suspension'.
Not so much of a problem on take off as models have a high thrust to weight ratio but on landing a flat underside surface can behave remarkably 'hard' as it touches the water which can cause a significant bounce.

How good is the watertight integrity of the hot glue joints? Are the floats going to be skinned in any way?
They do look to have fairly generous proportions.

The undersides have a shallow V hard chine up to the step & are flat at the back. I was fairly generous with the glue on the joints that have contact with water & ironed them to be sure they where sealed. I am not sure whether to cover them or not because of the weight, at the moment they weigh 3.5 oz each without the top skin. I was thinking of using waterproof polycrylic direct on the foam but I have to test it first as I have not used this foam before. I'm hoping to keep the finished article (undercarriage included) under 10 oz. For the water rudder I will probably use a snake driven from the rudder servo, although I have seen some that use a central mounted shaft driven one. Cross that bridge when I get to it! Like Paul, I also need to source the right wire for the undercarriage.

I have finished the two floats & started waterproofing them. Polycrylic works well direct onto this foam. Application by brush is; one coat neat left for four hours until tacky, then as many coats as you wish mixed 1 to 1 with talc powder & sanded in between coats. When you are happy with the finish top coat with whatever you want. In this case I will probably use polyurethane or exterior gloss. Pictures will follow when there is something worth looking at.

At 10 oz as well as both significant frontal and surface area I do wonder how much of the performance the floats will take away.

As the floats themselves usually have an excess of front side area you might consider some extra fin area to restore the lateral stability.

Valid point Q. As far as performance goes, I could always go from 3s to 4s I suppose ?
Increasing the fin area shouldn't be much of a problem, how much would you advise ?

Based on the float-planes I've seen, they have an under-fuz strake of about 25% of the fin area.
Similar performance loss due to drag from the floats. They are way over-powered, just to get off the wet stuff.

How much extra fin area? I suppose it depends on the degree of the existing lateral stability.
For the float plane Spitfire under fin was quite big but then it was designed for manoeuvrability so not intended to be super stable in any direction. A float Super Cub on the other hand seems to manage with no extra but I expect its substantial square rear fuselage give it good stability reserve.
I note that the Turbo Beaver , which is probably as high powered as a model, has a much bigger fin than the basic Beaver to start with and as float plane has a pair of sub fins on the tail plane as well.

Didn't the DH Beaver have a Wright engine similar to those in the Dakota?