Request For Tee Dee Help
03-27-2016, 02:08 PM
#26
I was coaxed into going flying yesterday even though I have an unusual propensity to build that I haven't had in years. Haven't flown since last fall either. Took three airplanes to the field - one of 'em being the GLH with the modded (1/8") venturi. Halfway to the field, realized I hadn't packed my 1/2A fuel and thought: "Shucks - I'm not turning back now."
Had Omega 10% with me and tried improvising FWIW by loading up the tank with a few drops of castor oil kept in my field box and then fueled up. This action comes from some guys that have talked about the necessity for a generous castor base on these engines and the paranoia on my part that resulted. Two head shims. Back the needle off 1/2 turn prior to start mostly just to break loose the needle for ease of adjustment. With a pessimistic attitude - so I'm never unpleasantly surprised - primed one time and cranked. Engine started easily. Kept glow driver on for a long while and leaned to near peak. Engine started to sag in various attitudes as it always did but exercised patience and laid off the needle for a while. At some point the engine settled into a decent, consistent power level and it felt good level and at ~ +,-15 degrees. I launched and had the best flight with the airplane I've had in years with this engine - was even able to do vertical turn-arounds at each end of the field - Alleluia!
The airplane put in a slightly short flight but pulled well throughout; after about 6 minutes, during one lower fly-by engine stopped abruptly, prop position stopped near vertical, without any hint of low fuel ( I used to get some extended bursts of power prior to emptying the tank and would go for altitude to get an extended glide.) Still had plenty of momentum to turn away from the runway and make a normal turn-around approach for uneventful landing. In looking the airplane over, appeared to have a good smell with nice, clear slimer down the fuse sides and over top of the wing. But then, "Oh-oh, the engine doesn't turn over well at all." Immediately, disastrous thoughts go through the mind: did I ruin the engine? Witness: "Did you ingest your venturi insert?" Me: "Oh yeah, I bet I did... no wait that looks okay... oh, wait a moment, my carb body's loose!" Witness:"Yeah, your retainer nut's right up against the drive plate." Been here before yet still took time to dawn on me; witness processed info quicker...
Is it fixed? I think so, but to be scientific about the whole approach to the problem and listening to some voice that's probably from some long ago conversation from some experienced, wise, old guys talking in the pits about "changing only one thing at a time and checking for a change - if no improvement, try something else... In actuality several things have changed here: four head shims down to two, 30% nitro down to 10%, and the venturi size shrunk and perhaps others like conditions and things I didn't even think of at the moment. I can't but help and think at this point it was the venturi size after all though. Need to try on the usual fuel next time...
Thanks to all again.
Had Omega 10% with me and tried improvising FWIW by loading up the tank with a few drops of castor oil kept in my field box and then fueled up. This action comes from some guys that have talked about the necessity for a generous castor base on these engines and the paranoia on my part that resulted. Two head shims. Back the needle off 1/2 turn prior to start mostly just to break loose the needle for ease of adjustment. With a pessimistic attitude - so I'm never unpleasantly surprised - primed one time and cranked. Engine started easily. Kept glow driver on for a long while and leaned to near peak. Engine started to sag in various attitudes as it always did but exercised patience and laid off the needle for a while. At some point the engine settled into a decent, consistent power level and it felt good level and at ~ +,-15 degrees. I launched and had the best flight with the airplane I've had in years with this engine - was even able to do vertical turn-arounds at each end of the field - Alleluia!
The airplane put in a slightly short flight but pulled well throughout; after about 6 minutes, during one lower fly-by engine stopped abruptly, prop position stopped near vertical, without any hint of low fuel ( I used to get some extended bursts of power prior to emptying the tank and would go for altitude to get an extended glide.) Still had plenty of momentum to turn away from the runway and make a normal turn-around approach for uneventful landing. In looking the airplane over, appeared to have a good smell with nice, clear slimer down the fuse sides and over top of the wing. But then, "Oh-oh, the engine doesn't turn over well at all." Immediately, disastrous thoughts go through the mind: did I ruin the engine? Witness: "Did you ingest your venturi insert?" Me: "Oh yeah, I bet I did... no wait that looks okay... oh, wait a moment, my carb body's loose!" Witness:"Yeah, your retainer nut's right up against the drive plate." Been here before yet still took time to dawn on me; witness processed info quicker...
Is it fixed? I think so, but to be scientific about the whole approach to the problem and listening to some voice that's probably from some long ago conversation from some experienced, wise, old guys talking in the pits about "changing only one thing at a time and checking for a change - if no improvement, try something else... In actuality several things have changed here: four head shims down to two, 30% nitro down to 10%, and the venturi size shrunk and perhaps others like conditions and things I didn't even think of at the moment. I can't but help and think at this point it was the venturi size after all though. Need to try on the usual fuel next time...
Thanks to all again.
Last edited by H5606; 03-27-2016 at 02:53 PM.
03-28-2016, 03:45 PM
#27
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Looking at the other changes I'd vote for venturi size.
Nice looking model. BTW what prop is that? EDIT: there's the answer in post #1 dummy.
Nice looking model. BTW what prop is that? EDIT: there's the answer in post #1 dummy.
Last edited by MJD; 03-28-2016 at 03:52 PM.
03-28-2016, 04:21 PM
#28
Higher compression with the 2 shims and the HC glow plug, I use small props for speed and 1 shim with a HC glow head.
NV is a fine thread for honing down the settings to peak. Choked down venturi after a previous boring out gave better fuel draw
with the right prop and good outdoor temps the engine will sing along happy and steady. Looks like a Cox 4.5x4.
Do you recall what brand fuel line? I had some back in the day cant recall now, the ID is good size for .049's.
Lower castor % providing the temps outside are okay will actually give more rpm with a good fitted piston / sleeve.
Too thick oil slows down the rpm the car guys like to get away with all synthetic for better top end for that reason and to avoid build up.
4cy engines cant use but a small amount of caster the nature of the engine design causes build up in the case to the point where it will gum
up the bearings and not turn over without preheating the case.
NV is a fine thread for honing down the settings to peak. Choked down venturi after a previous boring out gave better fuel draw
with the right prop and good outdoor temps the engine will sing along happy and steady. Looks like a Cox 4.5x4.
Do you recall what brand fuel line? I had some back in the day cant recall now, the ID is good size for .049's.
Lower castor % providing the temps outside are okay will actually give more rpm with a good fitted piston / sleeve.
Too thick oil slows down the rpm the car guys like to get away with all synthetic for better top end for that reason and to avoid build up.
4cy engines cant use but a small amount of caster the nature of the engine design causes build up in the case to the point where it will gum
up the bearings and not turn over without preheating the case.
03-30-2016, 03:21 AM
#29
I didn't physically measure prop diameter but the hub says 5 x 4. What it may lack in performance against customized props seemed to be compensated by its durability. Hence a "rubber ducky" moniker. I remember now I used to run a narrow blade T/F 5.25 X ?? white Nylon w/ red markings that worked well but ruined blade root area with the electric starter and was looking for a replacement...
From memory: I have a couple 4.5 x 4 molded in neon yellow I got from Cox International that may be why the engine seemed very happy with (when it had the large-bore venturi) but never seemed to pull this airplane with authority.
Fuel line was purchased at a hobby shop counter when they sold the stuff by the foot a long time ago so I don't know what brand.
From memory: I have a couple 4.5 x 4 molded in neon yellow I got from Cox International that may be why the engine seemed very happy with (when it had the large-bore venturi) but never seemed to pull this airplane with authority.
Fuel line was purchased at a hobby shop counter when they sold the stuff by the foot a long time ago so I don't know what brand.
Last edited by H5606; 03-30-2016 at 03:25 AM.
03-30-2016, 09:53 AM
#30
03-31-2016, 03:38 AM
#33
Regarding Uniflow tank - could the fill vent be omitted and tank be filled inverted through feed line?
Regarding bladders - is that a pressure bladder and what's a good source?
Regarding bladders - is that a pressure bladder and what's a good source?
03-31-2016, 05:00 AM
#34
You can fill them any way you wish. Little Red Caps are pretty good low pressure bladders. They are available for about $5 for 20 in a pack. Here we get them from Lee Valley Tools. I think Ace hardware in the US can get them ordered. They are used for caulking guns and work well for that too. They degrade after a few weeks when fuel is on them, and after a year on a caulking gun depending on conditions. You could try Texas Timers for standard latex tubing. I found the local medical supply had some well priced tubing in the 1/16", 3/16" and 1/4" size. A thin wall is preferred if you can find it. The TSC store has some 1/4" stuff that works ok for .15 size stuff.
Last edited by aspeed; 03-31-2016 at 05:04 AM.
03-31-2016, 05:07 AM
#35
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For suction bladders, good old balloons hold up a fair while and if you use a neck fitting that makes them easy to swap then they are not a big PITA. I soaked one in 50% nitromethane fuel for a few days and it really didn't suffer much.
04-01-2016, 09:45 AM
#36
If you want to use the pressure tap from the back plate, or better yet, the pressure tap on the carb body (best) , then the fill vent is not needed. You just invert the tank and fill through the uni-flow line that goes to your pressure tap and the tank is full once it comes out the feed line to the carb.
A large syringe and a wooden cloths pin is all you need to fill a pressure type bladder. I put the bladder in a balloon in case it bursts. Use the clothspin to clamp the line, and release it once the engine starts.
Another set-up it to use a small balloon inside a tank. The balloon is wrapped and sealed around the outlet fuel line. The vent goes to your pressure tap. First, blow on the pressure line to collapse the balloon inside the tank, to get all the air out of the balloon, Fill the ballon via the outlet line from the tank. When the engine is running the pressure from the pressure tap will push on the ballon and force the fuel in it to the engine. I beleive they sell kits for this, as my pal Larry Renger tells me the control line guys use this set-up.
A large syringe and a wooden cloths pin is all you need to fill a pressure type bladder. I put the bladder in a balloon in case it bursts. Use the clothspin to clamp the line, and release it once the engine starts.
Another set-up it to use a small balloon inside a tank. The balloon is wrapped and sealed around the outlet fuel line. The vent goes to your pressure tap. First, blow on the pressure line to collapse the balloon inside the tank, to get all the air out of the balloon, Fill the ballon via the outlet line from the tank. When the engine is running the pressure from the pressure tap will push on the ballon and force the fuel in it to the engine. I beleive they sell kits for this, as my pal Larry Renger tells me the control line guys use this set-up.
04-01-2016, 06:12 PM
#37
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It is standard fare in pylon and pattern models. Jett and Tettra make them, the smallest I know of is the Tettra 3oz. I've made some 1/2A versions with a film can and part of a 9" balloon, plus some tubing and nylon fittings. I was on a film can tank kick for a while, I still have a bag of 30 or so film cans to keep me in homemade tanks for the next decade or so.
04-08-2016, 01:01 PM
#38
If you want to use the pressure tap from the back plate, or better yet, the pressure tap on the carb body (best) , then the fill vent is not needed. You just invert the tank and fill through the uni-flow line that goes to your pressure tap and the tank is full once it comes out the feed line to the carb.
A large syringe and a wooden cloths pin is all you need to fill a pressure type bladder. I put the bladder in a balloon in case it bursts. Use the clothspin to clamp the line, and release it once the engine starts.
Another set-up it to use a small balloon inside a tank. The balloon is wrapped and sealed around the outlet fuel line. The vent goes to your pressure tap. First, blow on the pressure line to collapse the balloon inside the tank, to get all the air out of the balloon, Fill the ballon via the outlet line from the tank. When the engine is running the pressure from the pressure tap will push on the ballon and force the fuel in it to the engine. I beleive they sell kits for this, as my pal Larry Renger tells me the control line guys use this set-up.
A large syringe and a wooden cloths pin is all you need to fill a pressure type bladder. I put the bladder in a balloon in case it bursts. Use the clothspin to clamp the line, and release it once the engine starts.
Another set-up it to use a small balloon inside a tank. The balloon is wrapped and sealed around the outlet fuel line. The vent goes to your pressure tap. First, blow on the pressure line to collapse the balloon inside the tank, to get all the air out of the balloon, Fill the ballon via the outlet line from the tank. When the engine is running the pressure from the pressure tap will push on the ballon and force the fuel in it to the engine. I beleive they sell kits for this, as my pal Larry Renger tells me the control line guys use this set-up.
George
08-20-2016, 10:16 AM
#39
Yesterday, I took advantage of a calm evening to fly the GLH a couple times. It was one of those evenings - you know the type - fair skies, sun going down - though not quite down to the tree-line yet - no mosquitos yet - just the perfect summer evening. I put a 2-meter electric sailplane up and was enjoying a quiet and tranquil extended glide past - only sound is perhaps a bird calling it's mate in the distant background... and then it happens... a gaseous rip by the guy leaning against the flight-line barrier behind you...
So I tried the Tower/Hobbico/Cox fuel I bought a few months ago - a gallon that comes as a case of four quarts - 25%. I think I still have issues as related to this thread but the airplane pulls well in straight and level flight at shoulder height and ilicits a "Have you ever clocked that thing?" from a bystander. I tell them that its probably doing every bit of 40 mph. The engine sounds and pulls great in shallow dives to level flight but during longstanding climbs it starts to go a little ragged. As pointed out in this thread, I would like to try pressure bladders at some point. Gawd it smells good. I swear there is an aromatic they put into this fuel. By no means an endorsement but the slimy, clear after-mess smells so good - like a fine cheap aftershave cologne when wiping it off after running the stuff. Makes you wanna put a little behind the ears for good measure.
Tightened the plug and Put in a second flight after sunset; resorted to flying overhead in the waning light towards the end of the run to keep the - now just a silhouette - in view while patiently waiting for the engine to quit. This a.m. I was only able to pull drops from the tank.
My wife gifted me one of these El-cheapo cameras for ~ $40 so hopefully will be able to communicate more effectively in the future...
So I tried the Tower/Hobbico/Cox fuel I bought a few months ago - a gallon that comes as a case of four quarts - 25%. I think I still have issues as related to this thread but the airplane pulls well in straight and level flight at shoulder height and ilicits a "Have you ever clocked that thing?" from a bystander. I tell them that its probably doing every bit of 40 mph. The engine sounds and pulls great in shallow dives to level flight but during longstanding climbs it starts to go a little ragged. As pointed out in this thread, I would like to try pressure bladders at some point. Gawd it smells good. I swear there is an aromatic they put into this fuel. By no means an endorsement but the slimy, clear after-mess smells so good - like a fine cheap aftershave cologne when wiping it off after running the stuff. Makes you wanna put a little behind the ears for good measure.
Tightened the plug and Put in a second flight after sunset; resorted to flying overhead in the waning light towards the end of the run to keep the - now just a silhouette - in view while patiently waiting for the engine to quit. This a.m. I was only able to pull drops from the tank.
My wife gifted me one of these El-cheapo cameras for ~ $40 so hopefully will be able to communicate more effectively in the future...
08-28-2016, 05:32 PM
#41
Spent some time trying to use the included accessories and found a combination that looks like it will work. Used my old pylon race helmet and drilled a single 1/4" hole for a 1/4x20 nylon bolt. Has the added benefit of emphasizing the "geek" factor too!
Also used a bit of fanfold foam to put together a face-hugger sunshade for the handheld camera - got idea from the local bookstore Brit aeromodeling mag - just don't know how to turn the camera on or off without having to open/close the viewfinder...
Also used a bit of fanfold foam to put together a face-hugger sunshade for the handheld camera - got idea from the local bookstore Brit aeromodeling mag - just don't know how to turn the camera on or off without having to open/close the viewfinder...
08-28-2016, 07:45 PM
#42
Nice the helmet cam will get it done 
My sport cam has wi fi so I just turn it on / off with my cell phone shows a nice view on the phone.
I check my hat / cam position then hit record on the cell.
My sport cam has wi fi so I just turn it on / off with my cell phone shows a nice view on the phone.
I check my hat / cam position then hit record on the cell.
08-29-2016, 03:19 AM
#43
That's very cool; picture-in-picture and adjustments can be made in real time. I'm a little behind the times and somewhat resistant when it comes to hi-tech gadgetry - I don't think I can do it with my dumb style, flip-phone - wife and I have discussed moving into smart phones...
08-29-2016, 08:21 AM
#44
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You can even tape your iPhone to parkies for some quick aerial video.. works ok. No financial disparity there, no risk whatsoever.. 
I am a semi-Luddite, but I get along with a smart phone and the basics. They are quite handy.
I am a semi-Luddite, but I get along with a smart phone and the basics. They are quite handy.
08-30-2016, 07:34 AM
#46
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I know the word because people with iPhones, iPads, Ipods, tablets, headsets, computer implants, bionic limbs etc., call me one all the time. I had to look it up too. I'm proud to resist these things.
08-30-2016, 12:02 PM
#48
Last Christmas I upgraded to a monster 6.2in screen diagonally great for surfing the net all
media is reasonable to view even tv, movies if desired. The other I had been using for 5yrs.
Tech performance and screen size has improved greatly. Apps for all sorts of needs.
Took the pic with my work phone which is another smart phone 5" screen.
Truly a must for keeping up with work emails, calls, pdf's and doc. files dealing with
clients, reviewing plans etc. keeps me in touch away from the office and has bought
me free time many a day along with peace of mind.
media is reasonable to view even tv, movies if desired. The other I had been using for 5yrs.
Tech performance and screen size has improved greatly. Apps for all sorts of needs.
Took the pic with my work phone which is another smart phone 5" screen.
Truly a must for keeping up with work emails, calls, pdf's and doc. files dealing with
clients, reviewing plans etc. keeps me in touch away from the office and has bought
me free time many a day along with peace of mind.
08-30-2016, 12:32 PM
#49
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Card munch on the iPhone is one of the good ones. I always lose biz cards, they make good toothpicks and table leg shims. After having a laptop yanked away and being told use an iPad, after much chagrin I manage to function okay with it. I can access the internet, take photos, and make notes all by myself . Oh and buy games form the app store and play those. I'm not totally useless but certainly a front runner.
. Oh and buy games form the app store and play those. I'm not totally useless but certainly a front runner.
08-30-2016, 04:42 PM
#50
I use a 8" tablet in my 350Z reports many engine functions in real time through a wi fi up link from the
cars on board computer and stays in the car. But also use a tablet around the house the screen is 11" plenty
big for up close reading the news etc. I leave my desk top PC for paying bills as it has an on going subscription
to McAfee and my primary mail account etc. Has a 2GB graphics card for online gaming and a sound card
for front and back realistic sound effects for foot steps etc during shooter games every clue helps keep you
alive lol. I am 53yrs old and completely integrated with the tech since 1995. When in chill mode watching tv
and fiddling with the hobby I prefer the larger screen from the desk top. The monitor makes an easy to transition
with the eyes from the large screen tv. If I use the tablet too long it tends to start delaying the transition.
cars on board computer and stays in the car. But also use a tablet around the house the screen is 11" plenty
big for up close reading the news etc. I leave my desk top PC for paying bills as it has an on going subscription
to McAfee and my primary mail account etc. Has a 2GB graphics card for online gaming and a sound card
for front and back realistic sound effects for foot steps etc during shooter games every clue helps keep you
alive lol. I am 53yrs old and completely integrated with the tech since 1995. When in chill mode watching tv
and fiddling with the hobby I prefer the larger screen from the desk top. The monitor makes an easy to transition
with the eyes from the large screen tv. If I use the tablet too long it tends to start delaying the transition.