Placeholder in the hope that my 10-year-old son and I can bang this out by the deadline.

Hey, September 1951 was when I was born! I'll be following your progress. It would be neat to build a design as old as I am!

Originally Posted by Crist Rigotti

Hey, September 1951 was when I was born! I'll be following your progress. It would be neat to build a design as old as I am!

Owen (my boy) and I have been reviewing the plans, discussing RC mods. Rudder will be interesting. I've been thinking of how to integrate a tail wheel while keeping the keel. Hoping to hide the rudder and elevator horns in the fuse.

This one was on my "possibles" list too, I'll be interested to watch your progress

Hi hoffboy your photo of a Sparky in your post is mine! It first flew in 2008 and is still giving good service. It really is a good fun vintage R/C plane and does amazing rolls with the rudder. I kept the original rudder and added elevators, power is a Scorpion 2215-18. If you build it you will not be disappointed.
Alan
edit: I have just looked at your plan which looks like a cleaned up/redrawn version. I notice it states the span as 40 inches, the original span was 48 inches - is this an error or are you going to scale it down?

Originally Posted by ukengineman

Hi hoffboy your photo of a Sparky in your post is mine! It first flew in 2008 and is still giving good service. It really is a good fun vintage R/C plane and does amazing rolls with the rudder. I kept the original rudder and added elevators, power is a Scorpion 2215-18. If you build it you will not be disappointed.
Alan
edit: I have just looked at your plan which looks like a cleaned up/redrawn version. I notice it states the span as 40 inches, the original span was 48 inches - is this an error or are you going to scale it down?

Oh yes, you are absolutely right, I hadn't noticed that when I looked at Hoffboys plan, the original was definitely 48 inches. This plan is Hogal's CAD re-draw, so maybe was deliberately scaled down? Here is the original plan. I'm sure it would work OK at the scaled down span.

Originally Posted by ukengineman

Hi hoffboy your photo of a Sparky in your post is mine! It first flew in 2008 and is still giving good service. It really is a good fun vintage R/C plane and does amazing rolls with the rudder. I kept the original rudder and added elevators, power is a Scorpion 2215-18. If you build it you will not be disappointed.
Alan
edit: I have just looked at your plan which looks like a cleaned up/redrawn version. I notice it states the span as 40 inches, the original span was 48 inches - is this an error or are you going to scale it down?

I noticed that size discrepancy as well. The CAD plans printed at 48", so it's an error on the plan. Did you go with the lifting elevator, or a slab? Since we'll have discrete throttle control, and a functioning elevator, I lean toward a slab. Considering enlarging the rudder by moving the hing line forward so we can run the pivot down through the keel and pick up a tail wheel. But that might be complicating things unnecessarily. Just thinking about ground handling.

Love your Sparky! (Your photos are what inspired this build, in fact.)

Originally Posted by Sundancer

Here is the original plan. I'm sure it would work OK at the scaled down span.

Oh MUCH cleaner than my copy of the original plan and article. THANKS! I can see why Hogal thought it was 40" as that bit at the top is a tad blurry. I agree that scaled down would have probably worked fine, but I'm glad the CAD version printed at 48".

Matt, you caught me off guard with the “Sparky”.
The Comet Sparky was what first came to mind, since I built two when I didn’t know how!
I like the article that mentions the various “set ups” tried, and the lifting tail using two degrees of negative and the engine requiring no down thrust.
On my little Brigidier (on my blog), I used a lifting tail but set it just the opposite with about two degrees positive and still used down thrust.
Looking forward to your interesting build. Good luck.
John

Originally Posted by hoffboy

I noticed that size discrepancy as well. The CAD plans printed at 48", so it's an error on the plan. Did you go with the lifting elevator, or a slab? Since we'll have discrete throttle control, and a functioning elevator, I lean toward a slab. Considering enlarging the rudder by moving the hing line forward so we can run the pivot down through the keel and pick up a tail wheel. But that might be complicating things unnecessarily. Just thinking about ground handling.

Love your Sparky! (Your photos are what inspired this build, in fact.)

I kept the airfoil tailplane exactly as the plan, only mod is the addition of small elevators - about 3/4 inch but I can measure and confirm. The original article explains the importance of the lifting tail. Rudder is as per plan. The forward undercarriage does lead to the occasional ground loop but I kept as per plan as I think it is part of the plane's character. I made one mod to the wing, I sheeted the underside from the LE to the spar as per topside, makes me feel more secure when I pull a loop.
Alan

Originally Posted by hoffboy

I noticed that size discrepancy as well. The CAD plans printed at 48", so it's an error on the plan. Did you go with the lifting elevator, or a slab? Since we'll have discrete throttle control, and a functioning elevator, I lean toward a slab. Considering enlarging the rudder by moving the hing line forward so we can run the pivot down through the keel and pick up a tail wheel. But that might be complicating things unnecessarily. Just thinking about ground handling.

Love your Sparky! (Your photos are what inspired this build, in fact.)

I'd be inclined to keep the tailplane "as per"; if you did change to a flat plate I would expect that you would need to move the CG forward a bit. Sheeting the bottom lwing leading edge as ukengineman says is a worthwhile mod, but would only attain maximum effectiveness if you also web the spars with 1/16" balsa (grain vertical) for at least the inner 1/3 - 1/2 span to produce a full "D" box, probably well worth doing though.

Got the fuselage framed up, but it's looking like we won't have the time to continue working on this, so pausing for now. We'll get back to it one day though. Too sweet of a model to not complete.