CEF speed contest Design Discussions

Myself I gave up with the bladder .. felt like I needed another hand to get running ? then I realized I was stupid and did not get the fine thread precision needle set up I needed and I couldn't keep it from flooding!! I will try again later my set up with the engine mounted straight up / down with inlet on the bottom would be very hard to mount the setup/...For a good laugh I will tell u all I was drilling the vent into the mount got to 3/16 wow I said that really needs to be 1/4" , instead of reaming it I trotted to the shop and got me a drill bit ////   // got the plane in hand and was thinking I don't want to drill my hand but I need to turn it up go in slow soo there I went and about half way through the bit caught spun the plane in my hand and    next thing I new the wing and some of the fuse was in the floor   to see this was almost the end   . no not now stupid get the pieces and the glue and just fix it the best you can ...     CURTISS P40 Q two coats clear 1 primer time to sand . what a nice three day weekend  

getback wrote:Myself I gave up with the bladder .. felt like I needed another hand to get running ? then I realized I was stupid and did not get the fine thread precision needle set up I needed and I couldn't keep it from flooding!! I will try again later my set up with the engine mounted straight up / down with inlet on the bottom would be very hard to mount the setup/...For a good laugh I will tell u all I was drilling the vent into the mount got to 3/16 wow I said that really needs to be 1/4" , instead of reaming it I trotted to the shop and got me a drill bit ////   // got the plane in hand and was thinking I don't want to drill my hand but I need to turn it up go in slow soo there I went and about half way through the bit caught spun the plane in my hand and    next thing I new the wing and some of the fuse was in the floor   to see this was almost the end   . no not now stupid get the pieces and the glue and just fix it the best you can ...     CURTISS P40 Q two coats clear 1 primer time to sand . what a nice three day weekend  

That's the spirit Eric!   Don't let those little things bother you! I had to laugh though.. I thought those kind of things only happened to me! We're only human.

I'm not gonna let this "tank thing" beat me either. I had trouble getting the rear end-cap off when heating with the soldering iron. I had to cut into the cap with a cut-off wheel in the dremel tool and bend the cap out to grab it with pliers. I "still" couldn't get it off by heating. I was getting frustrated..    then I tried applying some paste-flux to the joints.. applied heat and it came right off!!   I removed the baffle I had installed and discarded it, then I moved the pick-up tube forward slightly and moved the uni-flow forward about 1/8" more than it was. I pulled the fill-tube out and shortened it to about 3/8" and soldered it back in, using a block of wood inside the tank to set the depth and hold it while I soldered. I made extra end-caps previously.. so I will solder another one in, leak-test and give it another go.

Concerning using a bladder. I dont think I would have been so successful, had it not been for my Sullivan Hornet 1/2A electric starter. I also found flooding a major issue. I'd put 2 bladders through (20cc) before I got it all sorted. I have to say having now run it a few times, it's fantastic. Closing the needle after each run. I just need to workout how to fix it to the model.

Cheers Mike 

Me again with yet another question. I've decided to make a new handle for speed events. How far appart should I make the line anchors.

Cheers Mike 

ebeneezer wrote:Me again with yet another question. I've decided to make a new handle for speed events. How far appart should I make the line anchors.

Cheers Mike 

How far apart are the holes in your bellcrank? That is the maximum. Wider spacing will make the controls more sensitive.

Phil

ebeneezer wrote:Concerning using a bladder. I dont think I would have been so successful, had it not been for my Sullivan Hornet 1/2A electric starter. I also found flooding a major issue. I'd put 2 bladders through (20cc) before I got it all sorted. I have to say having now run it a few times, it's fantastic. Closing the needle after each run. I just need to workout how to fix it to the model.

Cheers Mike 

Mike, I'm pretty sure I'm correct in this suggestion... but once you get the needle set for that engine, you should not have to touch it again unless you change your fuel mix. I believe that; in this order; the usual procedure is;

#1. fill the bladder..
#2. "clip" your bladder feed-line closed with hemostats/clamp, after filling..
#3. re-connect the engine feed-line..
#4. connect your glow-driver clip..
#5. "prime" the cylinder"..
#6. commence flipping (or using your Hornet starter) and be ready to quickly release the hemostat clip from the bladder-line, as soon as the engine starts.

Jim, Rusty, Ron,  and several other people; I would hope to correct me if I'm wrong on this.

EDIT: ALSO... I've heard Rusty mention having an eyewash bottle within arms reach, just in case the bladder "pops" and sprays fuel in your face... (you mentioned being on your 2nd bladder already..) Safety glasses are ALWAYS a good idea when working around running model engines.

Yeah Roddie, you are correct that's the recommended Rusty procedure. Although it's not the one I use. I am too slow releasing the hemostats once it fires on prime. However, I have no problem cracking the needle as soon as it fires. Go figure!

Either way you need to have that fuel clamped or the NV closed. If not it's flood city.

Trying to fix the "Fridge-Magnet" tank.



and decided to experiment..





Leak-tested the "Fridge-Magnet" tank... Nice and tight.. no leaks. I'll solder-up the smaller tank(s) tonight.

I do like the fridge magnet tank, looks neat. You might consider a pressure tap and run'er on pressure! Also, are you gonna mount tank with Velcro?

Mark Boesen wrote:I do like the fridge magnet tank, looks neat. You might consider a pressure tap and run'er on pressure! Also, are you gonna mount tank with Velcro?

Mark, I'm assuming you're referring to the thin one on the left. The larger one on the right; I named the "Fridge-Magnet".. because it had problems when I tryed to run it... so I rebuilt it with a short fill-tube and repositioned the feed and uni-flow tubes. I have not flow-tested it yet though. Prior to rebuilding it; I had to pressurize it, to get any fuel to come out... and my fill-tube placement was making it impossible to fill the tank. That was a big oversight.

The smaller tank actually looks more like a fridge-magnet... I agree. It's a little more than 1/2 the capacity of the larger one. I have not done the math yet... but it should be around 5 cc's.

The speed contest does not allow the use of mufflers, or else I would try my homemade muffler which can use a pressure tap.

I do plan on using a Velcro mount on the tank. The adhesive may not last long though.

Yep, the one on left.

I was thinking tapping into the side of case? I don't know, now that you mention it, I've never tried pressure with a reedie, but should be the same?

I do thing the guys with balloon type pressure tanks will have an definite advantage.

You could go with the larger "hook and loop" industrial type Velcro and a couple small screws into balsa side?

Mark Boesen wrote:Yep, the one on left.

I was thinking tapping into the side of case? I don't know, now that you mention it, I've never tried pressure with a reedie, but should be the same?

I do thing the guys with balloon type pressure tanks will have an definite advantage.

You could go with the larger "hook and loop" industrial type Velcro and a couple small screws into balsa side?

Tapping the crankcase on a Cox reed-valve engine would prevent the reed from functioning. The system relies on the vacuum and pressure created in the crankcase on the piston stroke. Up-stroke.. "vacuum"; pulls reed away from it's seat and pulls the fuel charge in. Down-stroke.. "pressure"; pushes the reed back against it's seat and closes off the fuel charge. That's why the back-plate to crankcase seal is so critical.

As far as bladders go.. they're reliable... but I like a challenge. The guys who will have the fastest engines, are doing things like lightening their pistons and such. That's a little beyond my skill set.

Thanks Roddie, I like your bladdered engine starting instructions. They certainly make a lot of sense. I will give them a try. I'm still trying to figure out a good way to mount the bladder in my model. Hopefuly the Pclips I ordered off Ebay will arrive tomorrow. By the way I've set the holes on my handle at 1 ins 5/16.

Cheers Mike.  

ebeneezer wrote:Thanks Roddie, I like your bladdered engine starting instructions. They certainly make a lot of sense. I will give them a try. I'm still trying to figure out a good way to mount the bladder in my model. Hopefuly the Pclips I ordered off Ebay will arrive tomorrow. By the way I've set the holes on my handle at 1 ins 5/16.

Cheers Mike.  

You're welcome Mike. As Ron Cribbs mentioned though... he closes the needle the same way that you do. I guess it's just a matter of what works best for you.. and hemostats are one less thing to have to keep track of.

If those clips you ordered don't work out... I had an idea for mounting your bladder. Find some large size safety pins and cut the clasps off. Roughen the ends with a nail file and glue them into your fuse. You could also mount them horizontally and use ties to secure the bladder. They're a cheap, sturdy, lightweight and streamlined approach to the task.

This photo is self-explanatory



EDIT: I can't take credit for this idea... I was curious of the method that Jim used on "Miss Ashley's" bladder-mount.. so I did a search for a pic.. and "voila"....

Just make sure wherever you mount the bladder, the center of the bubble is straddling the C/G.
By the way, that's a beautiful plane. I like the shaped firewall support where the fuel tube passes through. That's JP's plane isn't it?
Rusty

JPvelo wrote:

That's our own Fit90 Bob, I believe. The master of Cox pressure systems, and the guy that first outfitted me with bladder materials and my first ever Tee Dees, Medallion, Big Mig and too much more to list. You go, Bob!

The pressure vent is so tiny and the flow, once the tank is pressurized, becomes almost static so that it won't keep the reed from operating properly. Notice the check valve on this type of tap.
Rusty

RknRusty wrote:

JPvelo wrote:

That's our own Fit90 Bob, I believe. The master of Cox pressure systems, and the guy that first outfitted me with bladder materials and my first ever Tee Dees, Medallion, Big Mig and too much more to list. You go, Bob!

The pressure vent is so tiny and the flow, once the tank is pressurized, becomes almost static so that it won't keep the reed from operating properly. Notice the check valve on this type of tap.
Rusty

Hey Rusty, I had commented/replied to Mark B. about reedie crankcase pressure not being possible. I guess I stand corrected. I didn't know that they made check valves that small.

Yes, that's Jims plane in the photo, showing the bladder-mount. It's a beauty!!!!!!

Those valves are made by Fourmost. I heard they were going out of business, but the small filters and valves seem to still be available.
Rusty

RknRusty wrote:Those valves are made by Fourmost. I heard they were going out of business, but the small filters and valves seem to still be available.
Rusty

That's a shame about Fourmost.. a sign of the times it seems.. with many modeling-accessory companies. I know that "Tower Hobbies" stocks the Fourmost fuel-filter. It's on my wish-list for how to spend my $50 gift cert. that I got for my Birthday.

I did a little more tank work tonight. These all have slightly different feed/uni-flow positions. I switched from a 40w. iron to a 25w. iron and got better results... possibly a bad tip? I will close them up, flush/leak-test and try bench-running them tomorrow (Fri.)

Just a reminder guys, 26 days to finish your models by the March 31st cutoff.

Jim

Thanks for the reminder JP. I sure hate rushing these things, but it seems to be my way.
Rushin' Rusty