Tee Bee

For the last few weeks I've been tinkering with and flying some Parkzone electric models and started to feel guilty(The new P-47 with flaps and retracts is awesome!). I didn't want anyone to think I was losing touch with my glow powered roots so I decided to tinker with some 1/2A stuff again.

Anyhoo, here's my Scoundrel sporting a new Surestart engine and one of Bernie's throttles. I recently made a few short runs on my test stand using a Cox 6x3 prop and stock head. Not the setup that Bernie recommends but it was on hand. It was too dark to get any tach results so once I saw that the throttle had good potential, I decided to bolt the unit up to a plane for some real world testing. Skaliwag has been after me to slow down my Scoundrel since he saw it screaming around at SMALL last year, so choosing it for a testbed was a no-brainer. It's almost ready to run using a 5x3 prop and a Merlin head/plug. I had to add a shim under the cylinder to keep the piston from hitting the glow plug at TDC. Not sure how this will work out but I'm l'm looking forward to running it as soon as I can. The throttle is operated by a Futaba S3114 micro servo.

Should be fun to throttle the reedie back and make some slow passes, maybe even landing approaches. Stay tuned.............

The site isn't letting me upload pics. Will try again later.

Tee Bee

Here's the pics. The other project on the table is a Corkscrew from RCM plans designed by Stu Richmond. It will be powered by a giant .25FX so it probably won't be shown or discussed on this forum.

windy city

Tee Bee,
Boy is that still a sharp looking plane! I bet that throttle from Bernie will work just great on this plane.
I know 3-4 of you guys built them.
Any idea why that "skaliwag" never released any more kits? I've never seen them on his web site.

Fred

skaliwag

My Feedback: (1)

Good question..
Answer. I dropped the ball. I never got around to adopting the ideas and recommendations from the first few made plus making the corrections on the drawings and Laser Cut files. I have one Beta kit left if any one is interested. I will go forward next time I need some cutting done.
After SMALL I got into doing some .15 size C/L models. PT-19, P-51, Spit, and a P-40.
My latest project I have been working on is an .010 / Pee Wee size Eindekker looking baby.

jeffie8696

Where is the link to your site?

skaliwag

My Feedback: (1)

The Scoundrel isn't posted but here is the site.

http://selecthobbies.com/

jeffie8696

Cool thanks.

hfenn

Good job TeeBee. Also, I think the Corkscrew will be lots of fun. I remember seeing it when it was published and what stands out in my mind is that the fuael tank compartment was open at the front of the model. It is a neat looking low winger. I hope to see your throttled Scoundrel fly at SMALL '11!

Tee Bee

Thanks guys. Unfortunately, I won't be at SMALL '11. My daughter graduates HS that weekend. I tried to get the school district to change the schedule but they wouldn't bend. I hope to return in '12, though.

I hope to run the engine on the plane and set up the servo travel in the next day or so but flight testing will have to wait a while because it's getting cold and windy here.

Here's a pic of the largest gathering of Scoundrels in history taken at SMALL last June. Left to right Chris Sweeney with electric power, Steve Staples with PAW diesel power, Steve "skaliwag" Adams the designer, and me with Cox power. Thousands of miles were traveled to bring these planes and modelers together. What a neat hobby!

This was a fun build project and a good flyer. Nice lines, too. It would be nice to see more of them out there.

skaliwag

My Feedback: (1)

Danger Will Robinson, Danger.

windy city

skaliwag,
You had the opportunity to really spin up a good story, lol Thanks for the honest answer,,,,
"I have one Beta kit left if any one is interested."
Well if I'm not too late I might like to take that last one off your hands.
I'll PM you soon.
Fred

Got to talk to a skaliwag to get your hands on a Scoundrel, Man what a hobby! lol

hfenn

One of the few valid reasons for missing. That's why I was MIA '05 and '09!

LittleRock

Is there really a valid reason for missing SMALL ??

Tee Bee

Good question, Steve. Led Zeppelin or Britney Spears better be performing at the graduation ceremony.

Tee Bee

She's ready for flight-testing but the recent cold weather, a bad toothache, and work issues are keeping me away from the flying field. [&o]

windy city

Hey Tee Bee,

Any updates on your throttled Scoundrel?
yea I know its still FEB (cold), your still paying your bills (work), I hope the toothache is just a memory...
Any chance of a video? It would be neat to see the Scoundrel on a slow flyby.
thanks
Fred

Tee Bee

I'd love to report great success with this setup but I can't do that yet.

I took the throttled Scoundrel to the field a few weeks ago and got some flights in, some of them very short in endurance. It seems that every time I pulled the throttle back very far, the mixture would go rich and then the engine would quit if I didn't add power quickly. My static engine runs were more successful than the flight tests. I experimented with props(Cox rubber ducky 6x3 and 5x3) and alternated between a stock Cox head and a hotter Merlin head/plug combo. It did seem to be sucking some air in around the needle valve that day. I was able to hold a fairly consistent mixture when running full throttle and ended up just flying it that way for several flights. My Scoundrel has very little dihedral and small ailerons so it needs a bit of speed to maintain good control. Flameouts at low altitude can be a little hard on the nerves(and the plane) since our field runway is paved and the surrounding grass is currently sprinkled with crawfish tunnels which eat 1/2A plane parts. A controlled landing on the concrete is necessary for the plane's survival.

When I get the chance to try it again, I'll fit a piece of fuel tubing over the needle valve to eliminate the mixture surging that I was having that day. I also need to find out if the Merlin head/plug combo I was running is similar to the one that Bernie is selling for this setup. They look the same to me.

To sum it up, data is insufficient at this time. I'm hoping to try it again this weekend and get more consistent runs. I'd love to hear others' flying reports of the throttle.

P.S. After a tough extraction, the toothache ended. [X(]

Mr Cox

This is just exactly what this "throttle" is designed to do. Remember that this device is what is usually referred to as a choke, it restricts the air-intake before the fuel jet, hence increasing the fuel draw. Its main purpose/effect is simply to increase the fuel to air ratio. These chokes are commonly used as cold start aids on two-stroke engines.

To think that it will throttle an engine well, is expecting too much from it. All it can do is to richen the mixture and thus lower the rpm somewhat compared to a fully leaned out situation.

windy city

Tee Bee,
Glad you got rid of that tooth pain! That can be a real killer....
I know you will get this worked out. Back in your first post you typed
"I had to add a shim under the cylinder to keep the piston from hitting the glow plug at TDC."
Correct me if I'm wrong but doesn't that change port timing a bit? Wonder if that had any effect on the fly-ability?

Mr Cox made some good points there on the carb vs choke thing!
I wonder if you could find a combo of parts that would would work, even at the expense of some top end RPM. I don't know but theres single bypass, duel bypass, Texaco backplate vs a drilled out setup,, shims vs no shims, high compression, low compression, hot or cold plug, the list could go on forever,,,,,,, It would take some head scratching and some part swapping but i think you could find a good combo.
I bet you would trade some top speed for a half throttle Scoundrel fly by.lol
good luck
Fred

Mr Cox

This type of "throttle" was used some 50+ years ago but even then they were only used as a compromise (and simple add-on) on the smallest engines, like the OS .099 PET and their .15, the larger engines had a real carburetor.

Tee Bee

Mr. Cox is correct about the choke function of the throttle and I was aware of this going in. Still, some of my test runs showed promise of decent variable rpm control and as windy city mentions, there is probably an engine configuration that will allow better functionality of the unit. Certainly not as efficient as a carb, but possibly effective enough to have some fun with while flying around. Fun, afterall, is what this is all about.

BTW, I like the that PET .099 pic. Thanks.

MJD

My Feedback: (1)

So now you need a Perry IMC and a separate micro servo and endless fiddling with the mechanical linkage in order to lean the mixture appropriately as you pull back..

MJD

My Feedback: (1)

Speaking of that old Pet .099, check out the thread with the same engine on an RC Flite Streak!

windy city

"Fun, after all, is what this is all about."
Tee Bee, you got the right attitude, you'll get it working!
So you went out to the field and the little Cox just didn't run right, no big thing. You still flew, still have the plane, you had some fun,
Life is good!

I re-read my last post and didn't mean any disrespect towards Bernie. I know he has put a lot of effort into this throttle setup.
I'm sure it works just fine without all the parts swapping etc (Sorry sometimes my brain just goes Hmmmm)
He is a God send for all the Cox lovers out there!

Fred

Tee Bee

Agreed. I have nothing but positive comments about Bernie and his business.