SCREAMIN DEMON Small Block Bash
 

With MJD's permission of course and his down sized plans of the SD I found another use for my OS .25 VFDF, the wing span is 26" , should be fun, I've waiting for a full pipe set-up from MACS, then the fun will start, I'm installing a HOW FAST unit in this one.

RE: SCREAMIN DEMON Small Block Bash
 

It looks like a .90 in a standard size plane [X(]!
I'm willing to guess a 7x7 will be the best prop here.

RE: SCREAMIN DEMON Small Block Bash
 

Another one to add to the SD R+D craze.:D[>:]

RE: SCREAMIN DEMON Small Block Bash
 

Are those 3/16 or 1/4" balsa ribs laminated with ply in crucial areas? Should be interesting.

RE: SCREAMIN DEMON Small Block Bash
 

That's the way I built my first DD, with light 1/4" balsa ribs. The holes for the spars were oversized and packed with sawdust and thin CA.

RE: SCREAMIN DEMON Small Block Bash
 

thats 3/16 hard balsa with ply laminated in the crucial spots, up around the engine mount spars etc...

RE: SCREAMIN DEMON Small Block Bash
 

Yeehah! Demon parties on the horizon.. new models corkscewing into the frozen tundra at triple digit speeds. Sounds like fun..

MJD

RE: SCREAMIN DEMON Small Block Bash
 

Added the how fast tubes, and servos, hatch style, also finished glassing it too in the critical areas. The throttle servo took a little bit of head scratching, I forgot about it and said where am I going to put that, he only place really was in the next rib bay near the front, it 'll work fine.

RE: SCREAMIN DEMON Small Block Bash
 

Messin' around today building a cowl for the SD .25VF DF.
Any comments on improvements, or better ideas? Still not sure about the back end of the cowl, I'm waiting for my tuned pipe set-up, to fit.

RE: SCREAMIN DEMON Small Block Bash
 

Nice job wrapping that sheet around the front end!

RE: SCREAMIN DEMON Small Block Bash
 

Read Ed Smith's comments to Tom about ducting the cooling air. Or if you did, ignore this suggestion.

Here's something I did to the LE of one I am building for lektrik power, and I think this is a mod I may incorporate in the next run of kits. I added 1/16" shear webs to close the box. These are not vertical grain, nor are they intended to do anything much else than preserve the LE profile somewhat better between the ribs, as it tends to alternate between a NACA0006 and a thick flate plate as you move out with high tension coverings. Doesn't seem to be a major problem, but I can't help thinking this is preferable. And I think it looks better. It may add a percent or two of torsional stiffness but that was secondary to me with this one. I've considered widening the LE sheeting a bit and adding fillers like this to see what it does for the structure and flight characteristics, I'll make a prototype out of the next one to hit the bench. Gotta finsh the lekkie then do the Dynajet one. But those are both after the .65 version. So many stupid ideas.. :)

MJD

RE: SCREAMIN DEMON Small Block Bash
 

mike

its a great idea, evolving designs are the best!

RE: SCREAMIN DEMON Small Block Bash
 

Well just so everybody knows I didn't abandon this project, I was motivated by RVMAN and MJDs' progress on theirs so i started back at er, I had to add about 1/2" to the height
of the cowl to accommodate the fuse top style header, and now I'm covering it, pics to come.:)

RE: SCREAMIN DEMON Small Block Bash
 

Heres some progress this weekend, I just have to finish covering the hatch, and bench run the engine some more.
The pimple on the right side is the "How Fast" LED, highlighted with red covering.

RE: SCREAMIN DEMON Small Block Bash
 

Excellent work, bet you look foward to flight testing.

RE: SCREAMIN DEMON Small Block Bash
 

Yes, that really looks sharp! I'm amazed by the wood cowl, it wraps around the engine nice and tight.

RE: SCREAMIN DEMON Small Block Bash
 

For the cowl I just used some tri-stock and some fibreglass for the fillet transition to the wing, seemed to be smooth enough, I don't expect a 200mph bullet or anything but it would be nice to get it to the 150 + range.
Compact little thing, throw it in the car and go.:D

RE: SCREAMIN DEMON Small Block Bash
 

what method will you use to launch your self?

RE: SCREAMIN DEMON Small Block Bash
 

I'm working on a bungee launcher, but I reinforced the centre trailing edge with some fibreglassing, and I can hold the thing there and send it on its way like serving a platter of cookies.

RE: SCREAMIN DEMON Small Block Bash
 

what like a skid to hold? U got picture?

RE: SCREAMIN DEMON Small Block Bash
 

I think he means he reinforced the trailing edge in the center between the elevons, so it is strong enough to hold onto for a one-handed launch. If you fill in the gap between the elevons with TE stock and glass it around to the TE it makes for a tough handhold, or a good place to hook in to the restraint on the launcher.

RE: SCREAMIN DEMON Small Block Bash
 

I not seeing that postion you describe? Overhead launch

You could almost hold engine cowl for underhand launch if near cg?

RE: SCREAMIN DEMON Small Block Bash
 

Dude.. picture #4, the gap between the elevons. Hold there, point up, nail throttle, push hard and release. Some do it that way, but puss.. er, others like me insist on someone else launching.

There is usually nothing underneath to grip. The builder can add one if he wants, no problem there. The crankcase barely juts out the bottom, so usually just a bit of fairing is needed.

MJD

RE: SCREAMIN DEMON Small Block Bash
 

Heres a pic showing hand launch grip.

RE: SCREAMIN DEMON Small Block Bash
 

Looks like you have a tiger by the tail...