Roddie's CEF 2019 R.W.Y.B. Speed Contest prep..

F8F-2 Rare Bear flight-plan filed for 2019-07-28 (weather-permitting)

Engine; Cox .049 reed-valve/ExModel engine configuration (prize-engine from the CEF C.A.T.S. contest)
Propeller; DAL 5040R (left-hand/Reverse-rotation) quad-copter propeller.
Fuel-tank/capacity; Tin hard-tank/uni-flow-vented/6.15cc capacity.
Fuel-blend; https://sigmfg.com/ Champion-35
Line-length=35 feet

Off to a good start Roddie! What’s your cutoff for bad weather? 30mph winds and a downpour?

Ron

Cribbs74 wrote:Off to a good start Roddie! What’s your cutoff for bad weather? 30mph winds and a downpour?

Ron

.. yup.. well, it looks like it's gonna' be tomorrow afternoon Ronald. Not b'cause of the weather.. but rather; my OCD/in-preparedness. I'm a little-bit nervous too. (where's the smiley for that?) Also.. my "pit-girl" (Lynne) expressed her desire to color her hair.. and lounge in the swimming-pool..  

I actually plan to "1st fly" a few exhibition models at this new field.. to getback used-to turning circles before pulling the stooge-cord to a model; built primarily to go fast.. and turn left..

I needed to mount the engine in the Rare Bear.. and I did that today. There was a lot more to it.. than just 4 screws though. The engine needed to be re-configured with the cylinder facing outboard-circle and the needle facing inboard-circle. No big deal... but before mounting the engine to the firewall, the fuel-line needed attachment to the carb. This engine has the same high-performance carb. (Killer-Bee spec.) as was used for the 2014 CEF Reed-Speed contest.. where I needed to utilize a larger ID fuel-line to achieve a reliable suction-feed from a hard-tank. I took the same precautions, when affixing the feed-line this time.

The fuel tank is the same one that I made for this model back in 2014; a 6.15cc capacity uniflow-vented hard-tank. The mounting of that tank back then.. was sketchy. I wanted a better mount this time. I don't know if I've achieved that yet.. but I feel better about what I did today.

This hard-tank had previously been mounted with a single anchor-point to the fuse. There was no other adjustment. Today I took the time to devise an adjustment to align the tank for optimal exhaustion of the fuel-payload.. given the G-forces at work.










That's all I can give ya'll til' tomorrow..

Roddie, I would personally forego the use of uniflow if that's your vent facing forward. Switch your cap, cap off the uniflow and leave the vent open. It's not straight into the airstream and you have a lot of stuff out front such as the cowling which could cause turbulent air spilling into the pipe. This can cause all sorts of problems. As is right now, there's a good chance that it will cause a negative impact on the pipe rather than positive.

In addition, the size of the pipe which appears to be 1/8" is probably too large and possibly would require necking down. If your persistent on using uniflow, it might be more successfully accomplished by using a piece of 3/32" just slip fit inside of it, but better yet would be to obtain another cap like you show on the vent. Place that cap on the unfilow vent and put just a pin hole in the center of it. You fill through the uniflow and cap the vent. One thing I have discovered over the years is that those caps leak because they don't block off the pipe properly. Slipping a piece of fuel tubing over the cap can insure a tighter fit but they're not always leak free.

Obviously, flying it is most important to weed out issues. If it becomes an issue, I would place the uniflow pipe through the fuse exiting on the inboard side of the plane. Make the needed bends and have it come out just in front off and outside of your needle valve extension. You can then connect it to your uni pipe with a piece of fuel tubing. Seeing that you have the glow head and cylinder on the outboard side results in a lot of turbulent air entering the pipe. Getting clean air into the pipe is important.

I hadn't seen/read Ken's post (above).. until just now. If I'd read it prior to my flight-attempt.. I would have made some adjustments. The Rare Bear's engine was exhibiting symptoms in-line with what Ken warned about. I couldn't get the engine to draw fuel reliably.

The video below was the "first" vid of the day last Sunday. There isn't much to see until approx. 03:40:00.. at which point I get the engine started.. and it "throws the prop".. sending the engine into run-away with zero-drag on the crankshaft.  

If that engine didn't blow-up "then".. it won't ever blow-up. A testament to the quality of these little mills.



I've started working on the Rare Bear already.. to try and sort-out the fuel-delivery issue. I also put a pair of different (wooden) wheels on the mains.. and will assure a smoother runway to fly off. After watching my vid posted in the contest-thread, I think that Bob (rsv1cox) was correct in that; the airplane taxied-over a rough-spot.. before nosing-over and flipping end-over-end.

Roddie,
What kind of electric finger do you have there? It sure looks long.
My Sullivan Hornet just fits in my hand and may be wider. The Hornet barely spins the Medallion .15 on the Meteor.

944_Jim wrote:Roddie,
What kind of electric finger do you have there? It sure looks long.
My Sullivan Hornet just fits in my hand and may be wider. The Hornet barely spins the Medallion .15 on the Meteor.

Hey Jim, It's a homemade unit using an old 540 "can" motor. I built it almost 30 years ago.. but rebuilt the housing this past year. It used to be an aluminum tube.. and now it's clear polycarbonate.

Love those videos Roddie , they are a hoot .

Mike1484

Jim i dont think that Hornet was made for a .15 engine ? I could bee wrong , i dont have one ... I still want to make me one of the roddie style elect. fingers (( got the stuff just need to do it !! ))

Mike1484 wrote:Love those videos Roddie , they are a hoot .

    Mike1484

Thanks Mike, I hope to post more vids of me actually "flying".. rather than having problems..

getback wrote:Jim i dont think that Hornet was made for a .15 engine ? I could bee wrong , i dont have one ... I still want to make me one of the roddie style elect. fingers (( got the stuff just need to do it !! ))

My homemade starter was designed and built to engage the Tee Dee .049/.051 style aluminum spinner.. with a piece of 5/16" (I.D.) automotive-type rubber fuel-line.

My 540 "can-motor" was cannibalized from a portable 12V. air-compressor/tire-inflator. The motor has a small "gear" pressed-onto the output-shaft. The gear fits-into the short piece of hose.. and I've been using a hose-clamp to secure it. It works.. but I need a more "balanced" method of attachment. There's considerable vibration.. even when just "pulsing" the starter. It's because of the hose-clamp (worm-gear type). I've needed to attend to that..

I used a piece of fuel line/vacuum line and glued it inside my regular starter cone. I took a die grinder inside with the motor spinning to make sure it is true. I use it on all my motors, up to .55. I made a bunch of acorn style nuts for everything. The rubber is getting a bit sticky lately from years of fuel soaking but it works pretty good. The motor stalls first usually. I would like to use a 540 style one for the 1/2A ones though. All my motors from the dune buggy, carpet racers are not 12 V so I have not done it yet.

roddie wrote:

Mike1484 wrote:Love those videos Roddie , they are a hoot .

    Mike1484

Thanks Mike, I hope to post more vids of me actually "flying".. rather than having problems..

I didn't post my videos where I was swearing.

Cribbs74 wrote:Ok guys,

Even though we didn’t get enough participants Fred still wants this to move forward. I have solicited aspeed to calculate times as I could honestly use the help and I will post the voting polls for the other judged elements.

Ron

Hi Ron, You might want to move your post over to the official thread.. so that everyone knows what's going on.

I regret not being better-prepared for Phred's "R.W.Y.B." Speed contest. It just goes to show that; Model-Airplane "Pre-Flight" systems-checks are just as important as "full-scale". These checks can't be ignored or done hastily.

My reed-valve powered Grumman F8F-2 Bearcat (Rare Bear) entry had probable fuel-draw issues that I hadn't dealt with since the 1st CEF 2014 contest. I didn't know (for sure..) whether the airplane suffered from fuel-related issues.. or whether those 1st few fouled launches were to blame. Regardless.. I should have done more "this time"... to pre-test all of the related launch-systems.. and I didn't.   As usual; I was "Late for the Party".

I have done a little work to the airplane in the last few days.. but I believe that I need to experiment with a different fuel-system.. before the next trial-flight.

Here's a few photos that I shot tonight..





and these (below) are from 8/3/19..  

GB, that Hornet IS outclassed by the Medallion .15. I just got tired if fingering the the beast and getting no where fast. I really hoped the engine would light whatever it took!

Roddie,
I'll say it again...I love your tanks. They are well built pieces of art. The two on my BHM Mossie look like 1970's Soviet Union near-slave labor junk cans.

944_Jim wrote:
Roddie,
I'll say it again...I love your tanks. They are well built pieces of art. The two on my BHM Mossie look like 1970's Soviet Union near-slave labor junk cans.

Thanks Jim. I made several tanks when I first tried my hand at it. I found them all enjoyable to fabricate. I still don't know if any of them will perform for a speed-model though. They're "all" uni-flow vented. I should test some of the other ones that are different configurations/capacities.