Another Baby Streak

cribbs74 wrote:That Spar Urethane is some pretty tough stuff. The Polycrylic doesn't stand up to foot traffic, but may be fine on a plane. If I were you I would make up some test swatches and dump some fuel on it and see what stands up better.

I know I always say this........Top Flite clear... I run 25% all day long with spills here and there and it has never failed. It works and it's only $5-6 a can. I swear by it.

maybe i should have you send me some of the TF clear. it's about $7.88 here. it does work great though.

happydad

cribbs74 wrote:That Spar Urethane is some pretty tough stuff. The Polycrylic doesn't stand up to foot traffic, but may be fine on a plane. If I were you I would make up some test swatches and dump some fuel on it and see what stands up better.

I know I always say this........Top Flite clear... I run 25% all day long with spills here and there and it has never failed. It works and it's only $5-6 a can. I swear by it.

I actually have the dregs of a can of Lustrekote(same as TF I think?). That's probably best for the nose. The Minwax might be good for the rear end.

This Streak looks almost exactly like the one I built, except the leadouts are farther forward. Mine was tail heavy and this one is nose heavy. Mine weighs noticeably more too, maybe because of my liberal paint job. I always over-do paint, looking for that mirror finish. Plus I have a fiberglass repair under the tail from the maiden flight, the only time it's ever hit the ground.

This pretty baby came with a Norvel .061 on it. My red white and blue lead sled moves at 60mph with the Tee Dee. This new one might be a rocket with a Big Mig. I may trade engines, but I hate to mess with my old one that flies so well. I'll decide after testing the new one out. It's too freakin cold to fly lately.

On my test board polycrylic is stripped by raw fuel, quite quickly (minutes), but seems to hold up fine if coated with rustoleum. I used polycrylic for grain filling on 2 models that have not yet flown. I did not test either with exhaust.

I recall reading about someone using denatured alcohol to remove the high spots from polycrylic instead of sanding, prior to moving on to rustoleum or similar. I have not tested this.

Interestingly rustoleum over Testor's Wood and Metal Cement is a coating failure. The rustoleum simply falls off the Testor's when exposed to raw fuel and exhaust. The Testor's is quite fuel proof since it is celluloid. The rustoleum may not adhere very well for the same reason, (or poor surface prep).

I may get some top flight clear for the motor mount area. I have never had problem with dope.

Phil

Got it. The Minwax goes back in the cabinet. I'm going with the Topflite Lustrekote clear. I saw it at my LHS last time I was there.

RknRusty wrote:Got it. The Minwax goes back in the cabinet. I'm going with the Topflite Lustrekote clear. I saw it at my LHS last time I was there.

You won't be sorry.

I have not had good luck with MinWax Polycrylic. Several years back I was searching for a product to stick .5 oz. fiberglass cloth to foam wings. I wanted to stiffen the wing a bit and harden it to cut down on dents and dings, but didn't want to invest the time or weight in epoxy. Some finishing epoxys will attack the foam.

Polycrylic is one of the WBPUs, can be brushed and drys lighter than it goes on --- it is foam friendly. I was satisfied with the finished product, but ......

I had another plane that I was finishing up at the time, so with a little polycrylic left in the cup, I finished off the exposed wood.

Flew the plane a few days later --- IT WAS A STICKY MESS. I might as well have used honey. I understand there is another brand of WBPU that does hold up; Behr I think is the name. I know it's available in Canada.

I read in another thread that Behr did better than Minwax too. It may have been one of your old posts. Oh well, I'll stick with what I know. The Lustrekote is just heavy, but it's a really light plane so I guess I can afford the weight. I hope to have it ready next time I can get out to fly.

I'm curious to compare the two Streaks. I need to figure out how to fit an old Cox fine thread postage stamp NV in another Norvel so both can have the same type engine. The heavier engine will allow me to remove most of the nose weight from my old one. Or I could just use a wedge tank. Bah! I never have any luck with those.

I got'er done last night. I thinned some 30 minute epoxy thinner than I ever have before. It literally settled in the bottom of the container under a puddle of alcohol after mixing and I dipped the brush, dabbed it on a paper towel and painted. I painted the fillets and the gap between the fuse and wing covering, and the whole nose section. It went on and hardened like thin glass, beautiful. So I just have to mount the Norvel and balance it at the tail. It's nose heavy.

The camera doesn't do it justice. It really looks nice. I couldn't sand down to the pencil marks left by the builder. T/L on one side and T/R on the other.


My plan to swap engines with my old streak went south when I found the Norvel won't fit in the cutout without me removing more wood and refinishing. Fugettaboutit. But it was a good chance to check for fuelproofing integrity. It had no problems there. So I decided to take the Tee Dee .051 apart and check the piston rod slop and the internals. Couldn't get the cylinder off, and the lead plug I hammered into the backplate cavity prevents removing it without a lot of trouble, so I said the hell with it and put it all back together. I really did want to put the Norvel on it, but it flies good the way it is anyway. So the Norvel goes on the new lighter one.

Note to self: use aluminum safe RTV to secure lead to back plate cavities of engines since I can learn from others.

Phil

I don't have a picture of the lead in the regular backplate, but here it is in the Li'l Satan's radial mount backplate. It was one of those square sticky-back weights. It doesn't need to be glued it's in there and it ain't going anywhere.

Rusty,

The mount only needs to be tapered a small amount for the NORVEL and the mounting screw holes are the same.

Thanks for the heads-up on the RTV.

George

George, I know, but my reason is that I have sheet aluminum bearers epoxied between the engine and the wood that interfere with the crankcase. I decided I'd rather not tear it apart and re-do it while I'm in the midst of fixing up another plane. So it'll be something I can do after the other Streak is ready to grab and fly.

I've been tinkering with it for the past week getting it ready to fly this Saturday, weather permitting. I moved the engine mounting holes all the way back from the original position. I think they were originally moved forward to balance with no added weight. I added 1/16" aluminum bearers for the engine bolts on the inboard side of the fuse, and 1/32" bearers on the outboard side. They are epoxied on and will help keep the wood from compressing and also keep oil out.

You can see where I plugged the old front engine mounting holes. And also my newly added landing gear. It had none when I got it.


This is the thin aluminum on this side. I had to cut a notch out to accommodate the starter spring. I almost didn't have enough room to clear the front screw hole.


I mounted the engine and tried some lead on the inboard side of the engine cutout like I used on my other Streak, and a few grams balanced it. Then I realized if I put the muffler on the engine it balanced perfectly with no added weight. Voila, she's balanced. Although the muffler reduces power, the Big Mig has more thrust at full go than I need anyway with a featherweight plane like this. So even with the muffler I'll still be propping the power down with a 6" prop, at least for the maiden. I did that with the Refried bean and it flew great. A 5-1/2" prop made it too fast. That's the difference between 18kRPMs and 21.5k.

I never did do surgery to even out the elevator throw, but it has more Up than my other one and a little less Down. I'm hoping I find when I maiden, that it has just the right amount of Down but too much Up. Then all I need to do is solder a stop on the rod to limit the Up throw and that will be that.

Damn, I just reminded myself I need to add a guide eyelet because that's what the stop will hit. Plus, the rod is too long not to flex. Oh well. it's always something.