Author Topic: Yet another Super Duper Slow Rat (Read 1546 times)

Mike Callas · « **on:** November 08, 2011, 08:56:06 PM »

Look out.
Brodak's version of the Dave Braun design Super Fly
1 week glueing sticks together. 3 weeks covering and painting with Polyspan and dope.
OS 25FP. APC 8X6. 1.25 oz tank. 60' lines.
Rock steady in the air. 7 laps 20.6 sec. I think I can get into the 19s once I get it to run consistant and play with props.

Al Ferraro · « **Reply #1 on:** November 09, 2011, 06:21:37 PM »

You'll have to drop another 5 seconds to keep up with these two Slow Rats !!!

Les Akre · « **Reply #2 on:** November 09, 2011, 08:41:18 PM »

Looks good Mike!

When I ran an.25FP in SSR, I found the old style 7.8x7 APC (the one with the sabre shaped blades) worked really well. Got me down into the low 19's.
The 8x7 APC Sport Prop works well too, only a few tenths of a second behind the 7.8x7.

Les

Mike Callas · « **Reply #3 on:** November 09, 2011, 09:01:40 PM »

Quote from: Al Ferraro on November 09, 2011, 06:21:37 PM

You'll have to drop another 5 seconds to keep up with these two Slow Rats !!!

Al,
I nearly soiled my pants until I realized those planes are Slow Rats, not SSR! What motors do you run on them?

Les,
Thanks. I tried a 7.8X7 today (based on your comments to a previous post) and I could not twist it up enough. My FP was an old trade so I need to score another motor. Right now the Brodak 25s are out of stock. I'm on the hunt for a new e-bay OS 25fp. I am playing with the tank to get a solid steady run. I have been moving it outboard and it seems more consistent.

I know I should not worry about speed so much so I'll probably run an FP until I get the racecraft and restarts up to snuff.
That said, what are folks running for 7 lap times-low 19s???

Mike

Al Ferraro · « **Reply #4 on:** November 10, 2011, 08:19:10 PM »

Mike,
I am using a Go .25 RC truck engine (with my Blaster Mods). I use a 7x6 prop that the engine turns 25,000 RPMs on the ground. In a test session this past Sunday the plane turned 14.8 for 7 laps using S&W 10% nitro 20% oil fuel. When I read your post title, I thought you were writing about Slow Rats not SSR.
Al

Les Akre · « **Reply #5 on:** November 11, 2011, 02:30:11 AM »

Hi Mike

Hmm, you say you can't twist it fast enough with a .25FP, so I have to ask...what is your venturi diameter? I was boring mine out to .312 or 5/16" diameter when using the O.S. Needle valve assy. That really wakes em' up. If you're intent on finding another engine, I would recommend looking a bit harder for a Brodak .25. The Brodak Piston/Liner is far superior to the O.S.'s nickeled ABN unit, and is fit tighter at TDC. which really helps the re-starts. The FP doesn't like to re-start as well when hot, but you can do the water bottle trick with them (ie. hosing down the cylinder with water during the pit stop).

My local hobby shop usually stocks the Brodak .25, but I see they're out of stock at the moment as well.

Les

Mike Callas · « **Reply #6 on:** November 11, 2011, 01:47:15 PM »

Quote from: Les Akre on November 11, 2011, 02:30:11 AM

Hi Mike

Hmm, you say you can't twist it fast enough with a .25FP, so I have to ask...what is your venturi diameter? I was boring mine out to .312 or 5/16" diameter when using the O.S. Needle valve assy. That really wakes em' up. If you're intent on finding another engine, I would recommend looking a bit harder for a Brodak .25. The Brodak Piston/Liner is far superior to the O.S.'s nickeled ABN unit, and is fit tighter at TDC. which really helps the re-starts. The FP doesn't like to re-start as well when hot, but you can do the water bottle trick with them (ie. hosing down the cylinder with water during the pit stop).

My local hobby shop usually stocks the Brodak .25, but I see they're out of stock at the moment as well.

Les

Les,
I found a B25. I should have it next week. I'll break it in per your instructions found in this forum.
I think the venturi is already large enough. When I launch the plane it sputters and wheezes for a quarter lap. Then it clears its throat and runs ok.
For cool off fluid will beer work as well as water?

Mike

john e. holliday · « **Reply #7 on:** November 12, 2011, 09:04:48 AM »

Don't waste the beer on cooling the engine or is that what you meant? Beer is for cooling off the pilot.

Remember you have to pour it over his head. Won't work on a pit man as we have to wear helmets now.

bill bischoff · « **Reply #8 on:** November 12, 2011, 06:01:53 PM »

Don't the pilots also run on alcohol?

Les Akre · « **Reply #9 on:** November 13, 2011, 09:27:43 PM »

Mike

Re; your sputtering and wheezing.

I had another look at the pic that shows your fuel tank. I see a total of 4 tubes poking out of the top of the tank. I assume the longest brass colored one is your fill/uniflow tube and the one pointing toward the back of the engine, close to the fuselage is your overflow?? That leaves the other two at the front of the tanks outboard edge. All of these look to be vented to the atmosphere, unless some are internally plugged where I can't see it in the picture. I would recommend blocking off the overflow with a piece of fuel tubing running through some sort of pinching mechanism (alligator clip soldered to the side of the tank etc.) and plugging, or removing the other two tubes and soldering a piece of tin over the holes. A proper uniflow tank should solve most fuel feed issues and any odd running characteristics in the air. For the brodak, boring the venturi to .330" diamater and using either a 7x6 Taipan, or an 8x5 APC sport prop seems to be the way to go.

The beer works best after the race is over, to celebrate the win.

Cheers, Les

Mike Callas · « **Reply #10 on:** November 13, 2011, 10:55:15 PM »

Les,
The tank is a modified Brodak tank. The 2 vents to nowhere are plugged. I plan to clamp the vent with an alligator clip soldered to the tank.
Do you know if Todd Ryan still sells tanks? I tried to e-mail him, no response.

Thanks

Mike

Les Akre · « **Reply #11 on:** November 14, 2011, 04:04:21 AM »

Mike

I saw Todd about a month ago on the return trip from the Virgil Wilbur, he'd been kept occupied with a promotion at work, and with Sport bass fishing.
Model airplanes didn't seem high on the priority list. Give me a day or two, I probably have a tank laying around in the shop that would work.

Cheers, Les

Mike Callas · « **Reply #12 on:** November 15, 2011, 03:32:56 PM »

Les,
That would be awesome. Please send me a PM if you find something.
My Greek friend Basile Mandakis (BJM) sent me a new B25. Break-in this weekend.

BTW, what plug should I use in the Brodak 25??
For fuel I'm assuming 10% nitro 20% oil 50/50. 7X4 prop to start.

Thanks

Mike

Les Akre · « **Reply #13 on:** November 15, 2011, 06:57:44 PM »

Mike

I found a tank that I can modify, but I need a measurement from you on how much space there is between the engines backplate, and the landing gear leg. I plan to make the capacity around 33cc, which should be more than enough, and will install a tire valve overflow for you as well. From what I saw at the Virgil Wilbur, just about everybody was in danger of over running, so 33cc should be fine. Does $25.00 shipping included sound alright with you?

As for the glow plug, any sport plug will do as long as it's in the hot heat range. I would use an 8x5 APC for the initial run in, and needle the engine so that it just gets into a steady 2cycle. Run for about 20 seconds using 10% nitro 20% all castor fuel (although 10n 10/10 oil is ok too), then shut down and wait until cool to the touch. Do this again for another 10 cycles running the engine for 10 seconds at a time, then put into the airplane and go fly.

Cheers, Les

Balsa Butcher · « **Reply #14 on:** November 16, 2011, 02:41:41 PM »

Just for grins.

. here's my version of the same plane. Set-up for Fox Race though.

Mike Callas · « **Reply #15 on:** November 16, 2011, 09:28:04 PM »

Cool looking plane Pete!
Is that a Shy Fox?
Whats in the foam shucks? Secret weapon?

Mike

Mike Callas · « **Reply #16 on:** November 16, 2011, 09:29:12 PM »

Quote from: Les Akre on November 15, 2011, 06:57:44 PM

Mike

I found a tank that I can modify, but I need a measurement from you on how much space there is between the engines backplate, and the landing gear leg. I plan to make the capacity around 33cc, which should be more than enough, and will install a tire valve overflow for you as well. From what I saw at the Virgil Wilbur, just about everybody was in danger of over running, so 33cc should be fine. Does $25.00 shipping included sound alright with you?

Cheers, Les

That sounds great Les! Can you take paypal?

Mike

Balsa Butcher · « **Reply #17 on:** November 16, 2011, 11:40:46 PM »

No, this is a Shy Fox

, the first pics are of a Super Fly with a modified fuselage top. Just didn't like the look of the simple canopy provided in the kit. You'rs looks real nice as well-needs a canopy though

. Foam in background is hiding an SV-11 wing, yes, I sheet 'em myself.

Les Akre · « **Reply #18 on:** November 17, 2011, 12:23:38 PM »

Hi Mike

Check your PM

Cheers, Les

Author Topic: Yet another Super Duper Slow Rat (Read 1546 times)

Mike Callas

Yet another Super Duper Slow Rat

Al Ferraro

Re: Yet another Super Duper Slow Rat

Les Akre

Re: Yet another Super Duper Slow Rat

Mike Callas

Re: Yet another Super Duper Slow Rat

Al Ferraro

Re: Yet another Super Duper Slow Rat

Les Akre

Re: Yet another Super Duper Slow Rat

Mike Callas

Re: Yet another Super Duper Slow Rat

john e. holliday

Re: Yet another Super Duper Slow Rat

bill bischoff

Re: Yet another Super Duper Slow Rat

Les Akre

Re: Yet another Super Duper Slow Rat

Mike Callas

Re: Yet another Super Duper Slow Rat

Les Akre

Re: Yet another Super Duper Slow Rat

Mike Callas

Re: Yet another Super Duper Slow Rat

Les Akre

Re: Yet another Super Duper Slow Rat

Balsa Butcher

Re: Yet another Super Duper Slow Rat

Mike Callas

Re: Yet another Super Duper Slow Rat

Mike Callas

Re: Yet another Super Duper Slow Rat

Balsa Butcher

Re: Yet another Super Duper Slow Rat

Les Akre

Re: Yet another Super Duper Slow Rat