Oh yes - I love titanium bolts too - unfortunately these once are a bit too short - but do not worry, I have longer ones (-:

I did not have super much time to built today, but, oh boy, I am really happy about today’s progress.

The laminated firewall did not come out perfect but fairly well for yesterday’s hasty approach. I test fitted the engine one last time and look for yourself - all looks good. I can still move the cowl quite a few mm in all directions and to achieve a perfect fit is possible.

I removed the engine and glued the firewall and my self-milled “custom fitted” engine box top into place with slow curing epoxy (for the carbon parts) and aliphatic glue (for the wooden engine box top. Btw, I will add a removable top for the ignition. Just in case I need access to the carburetor, a removable solution will be much easier...

I also already glued in the front spruce stringers (thank you Pilot RC for supplying excess materials with the planes).

So next will be the milling of the new, additional engine box bottom. After glueing that in, I will cover the outside of the engine box with thin carbon (1 layer) and fuel proof the interior with epoxy (hopefully thinned if I figure out how).

Some more thoughts - I have lots of respect towards the weight of the Valach. 4 kg and then some require a stable engine box not to bend (or break) simply under the weight. This is much different then all electric planes I have built so far... I am curious how the CG will finally play out. Servos to the tail seem nearly mandatory now. Feeling sorry for my servo tray. Maybe I will repurpose (if needed) for the central box alone. I will likely cover wings and rudder first and see where I stand with CG. Then to move components around till all fits and then cover the fuselage...

Excellent Progress, Coming along well.

Regarding the Motor box and the Weight of the 140, I would use an extra ply doubler perhaps on the inside of the motor box , So going from the front of the box going a few inchs past the firewall, Thats should make it plenty strong.

If you have the cut files this should a be a Quick job Keep the lighting holes etc as well. Or Mill it from carbon

Yeah you will need the Rudder servo in the Tail as a Push pull, Get it as far back as you can. Batteries will be around the rear of the canopy area i think.

In case I missed it and just out of curiosity, what type of plywood are you using thriughout your airframe, and what thickness is utilized in your motor box?

Thanks in advance,

Bob

Hi Bob, the wood is a bit of a mix, as I changed the concept of motorizations significantly - from light electric to rather heavy 4stroke. In General it is mostly 3 mm Poplar ply, as it is light, cheap and easy to mill. This is consistent with Dan‘s original concept, as far as I can judge.

The inner fuselage sides (that extend to form the sides of the engine box) are doubled-up to be 6mm (also poplar). I will laminate carbon over it in the engine area - for fuel protection, optics and increased stability...

The firewall is 3mm aircraft grade birch plywood, doubled to 6mm and with two layers of 160g carbon- one to the front and one between the layers of plywood.

The top of the engine box is birch plywood also (3mm). The removable ignition holder will be 3mm ply.

I use birch sparsely as it is heavier and far more expensive. The wing tube reinforcements will be out of birch and the rudder main former is also. Same for the tailwheel „holder“. I only use it when I feel stability is really needed...
All else is poplar.

Btw, I tried out several poplar plywood providers until I was happy. I saw ply that delaminates, was rather 3.5 than 3mm or was optically perfect but very difficult to mill - the glue of the Wood apparently cloaked up the mill. Now I am happy. And somehow here quality somehow does not coincide with price...

I hope this helps...

Hi Hodge - quick question - when you write push/pull, do you mean 1/2 servos on one side of the rudder, or (much harder to realize) one servo on each side of the rudder?

I would go for the first solution for simplicity...

Originally Posted by Schlumpfi

Hi Bob, the wood is a bit of a mix, as I changed the concept of motorizations significantly - from light electric to rather heavy 4stroke. In General it is mostly 3 mm Poplar ply, as it is light, cheap and easy to mill. This is consistent with Dan‘s original concept, as far as I can judge.

The inner fuselage sides (that extend to form the sides of the engine box) are doubled-up to be 6mm (also poplar). I will laminate carbon over it in the engine area - for fuel protection, optics and increased stability...

The firewall is 3mm aircraft grade birch plywood, doubled to 6mm and with two layers of 160g carbon- one to the front and one between the layers of plywood.

The top of the engine box is birch plywood also (3mm). The removable ignition holder will be 3mm ply.

I use birch sparsely as it is heavier and far more expensive. The wing tube reinforcements will be out of birch and the rudder main former is also. Same for the tailwheel „holder“. I only use it when I feel stability is really needed...
All else is poplar.

Btw, I tried out several poplar plywood providers until I was happy. I saw ply that delaminates, was rather 3.5 than 3mm or was optically perfect but very difficult to mill - the glue of the Wood apparently cloaked up the mill. Now I am happy. And somehow here quality somehow does not coincide with price...

I hope this helps...

Again, I was just curious, so thank you very much.

Bob

Originally Posted by Schlumpfi

Hi Hodge - quick question - when you write push/pull, do you mean 1/2 servos on one side of the rudder, or (much harder to realize) one servo on each side of the rudder?

I would go for the first solution for simplicity...

If you going to Fly it more imac and not Huge 3D Action 1x Servo will be fine, around the 40-45 Kg Mark will do it well, its a pretty big rudder

Or you could run two on one side in tandum if lwoer torque you looking for endless rudder knife edge work and flips hahah

Originally Posted by The Hodge

Excellent Progress, Coming along well.

Regarding the Motor box and the Weight of the 140, I would use an extra ply doubler perhaps on the inside of the motor box , So going from the front of the box going a few inchs past the firewall, Thats should make it plenty strong.

You think he needs more wood in the motor box?

Bob

Actually no, forget what I said lol I was stuck in the 120cc class design, that doubled 3mm sides will be fine

The Valach is only 500 grams more , but yeah have a nice 10-12mm thick firewall

Hello again,

What does your fuselage, with canopy and engine cowling weigh right now?

Thanks in advance,

Bob

Hi, do not know the weigh of the cowl, the fuselage without canopy will be around 2.7 kg right now. Will measure tonight for you. Btw agree on the servo setup that hodge proposed. Re firewall, I hear your concerns. Remember that the 4stroke shakes less than the 2stroke engines, thus putting less strain on the airframe. I have already put sturdy triangular spruce (1cm) around the firewall. I want to see how this holds up once I cover the front sides with CFK (and the spruce also). If any doubt, the firewall gets thicker or more support.

Btw, I started building the elevator, currently remilling some parts, will send some pics soon

Ok the weighing is in...

Cowl ca. 500g
Fuselage (with two rudder servos, firewall installed and clamps for mufflers) - 2910 g
Canopy with frame ca 400 g
- Mufflers 290 g each
- Rudder (not sheeted on one side 150g
So 4.7 kg until now - add weight for wings, covering, engine etc...

I am not familiar with that engine, do you know the weight with ignition prop and spinner?

Bob

4183g with ignition, with starter around 500g more

Spinner and prop - do not know, depends on what you use (-:

Any chance you can tell me the wing area of this airplane?

Thanks again,

Bob