Screaming Demon big block bash
 

This is not official build here, as in laser cut prototype parts and all that. This is a good ol' bash-it-on-the-bench build, mostly because I have more than one idea about nearly everything I need to tweak. So this works better than staring at a monitor.. and more fun.

I am sticking with the wing size, and kludging together a structure around the tank area to make up for lost integrity in that area. Also, I have doubled up the front half of the center ribs, and have added a pair of spars just behind the carb inlet which will tie in to the LE, and whatever else comes as I go. I am pretty sure I can keep it under 4 pounds. I'll extend the rear spar right through the tip to the vertical fins to tie it all together. And I might use something more substantial than 1/8" balsa for the tip fins too..

The LE sheeting will extend further back, and will be supported with sub spars and webs to preserve the airfoil shape a bit better. I'll be using Ceconite fabric covering again, and it stretches so tight it nearly flattens the sheeting without help.

I have a pair of CF "D" speed props coming, I'll get those on the engine and on the test stand when they arrive.

If this holds together, and if I do, it could be my ticket to 200. And it is a small enough project I'll get it done in this lifetime too, that helps. Maybe even this fall, but I'm learning not to make optimistic claims.

MJD

RE: Screaming Demon big block bash
 

Oh I forgot. Pictured is my conversion of a Hangar 9 11 ounce clunk tank to a bladder tank. I heat sealed a moderately heavy walled poly bag in to a tapered neck shape, added a pressure inlet to the rear of the tank, sealed in the bladder and pickup, and voila. Comnpletely sealed tight. Now I have a bubble-free tank that allows the pipe to sit flatter and just gives more room - here, a cylindrical tank is a disadvantage, so I'll use the Jett 12 oz in something else.

RE: Screaming Demon big block bash
 

How much bigger will this end up being?

RE: Screaming Demon big block bash
 

Bigger..? ;) See par. 2. The wing loading will be fine, I've already weighed up a built airframe with all the bits and added kludge factors and it still comes out a fair bit under 4lb.

I've considered adding 4" of span - the max for the spar stock length - but keeping the chord dimensions the same for a .60 version. The area increase is 15%, seems about right. I'd make a few simple mods to the structure. This would be a bit more user friendly I think.

The version I'm doing here is more of a cackling and wringing the hands in glee version, but we'll see how things work out.

MJD

RE: Screaming Demon big block bash
 

Cooollll... I can hear the evil bwaahaha all the way down here.

RE: Screaming Demon big block bash
 

If I phone you right after impact, I should be able to catch you in time to run outside and hear it live.

MJD

RE: Screaming Demon big block bash
 

Great work, Didn't know you could make your own bubbless tank too. I never tried one, Just need to understand the heat shrink process.

cant wait to see that engine kick ass

RE: Screaming Demon big block bash
 

Anyone ever notice what the Germans use for tanks?

RE: Screaming Demon big block bash
 

Panzer

RE: Screaming Demon big block bash
 

ROFLOL, that was too good.

RE: Screaming Demon big block bash
 

LOVIN ITTTTT!:D:D

That engine mount should be plenty beefy also.

RE: Screaming Demon big block bash
 

Here is my contribution to the 'big block' developments. We shall see how I'm going to fit a reciever, rx battery and throttle servo all in that little space behind the fuel tank. :eek:

Enjoy,

Tom

RE: Screaming Demon big block bash
 

Is there something wrong with RCU's picture uploader?

RE: Screaming Demon big block bash
 

Things are gonna get wild in Southern Ontario this spring! Triangular craters everywhere..

COOL

I have to wait until Thursday to mill my mounting plate.. tap tap fidget fidget..

MJD

RE: Screaming Demon big block bash
 

Hopefully just yours for entertainment purposes. :)

RE: Screaming Demon big block bash
 

Tom just figure on setting some of it in an outboard rib bay.

That's going to be a fun one!

RE: Screaming Demon big block bash
 

4 cell flat packs fit fine in the rear bays. Mine is in the left rear to help offset side exhaust engines.

MJD

RE: Screaming Demon big block bash
 

Yeah, the next issue I had to figure out was the needle valve since it would end up inside the wing.. Thought about it for hours and then finally the light came on. I simply made a plug for the hole and will just use a remote valve mounted somewhere else. You probably have the same thing with the OPS?

Tom

RE: Screaming Demon big block bash
 

Yeah, on the .65 with the Jett .90 carb it needs a remote needle. I plan to fit a Perry remote NV to mine so I can twiddle it in flight which is generally recommended for running these things balls to the wall on an open pipe for RC speed. Once I think I can fly it and it still exists, I may switch to a venturi and pressure (and RNV).

MJD

RE: Screaming Demon big block bash
 

When do we get to see the kits FS?:)

RE: Screaming Demon big block bash
 

This is still the R&D phase, also know as "the part where I find out how stupid this idea really is". RVman is also playing guinea pig with his own mods. I know a guy with a Webra .80 DF that might think about this too..

Actually, the way my head works I'll have a much easier time drafting out the kit mods for RI engines after I hack one together and figure out what I like best. I am looking at mods to the existing design to make it more RI friendly in stock kit form, and this is separate from the idea of stuffing bigger engines into the airframe. Also one other major change I want to inflict upon it is to rearrange/revamp the structure to accomodate fuel centered over the CG.

MJD

RE: Screaming Demon big block bash
 

The C/L Speed planes and what I've seen of some of the SpeedCup planes use form fit tanks...somehow they control foaming without baggies? Or they have figured out how to make form fit baggies to fit those custom fit tanks? There hasn't been much talk about this detail that I'm aware of.

RE: Screaming Demon big block bash
 

some use a type of foam from auto racing fuel cells, and most just soft mount the tank to the pan with RTV or goop, but they all are using case pressure.....

RE: Screaming Demon big block bash
 

Those guys would think that a 50cc Husqvarna would be about right for a Screamin' Demon :D

RE: Screaming Demon big block bash
 

lol, back to the bladder issue, some use the baby bottle liners to make the bubbleless bladder tanks