RICKSTUBBZ

Nicolas

Prop selection is full of compromises. What gives an advantage in one way takes away something else. Just like the right thrust debate, there are different lines drawn in the sand of props.
Here are a couple of things that you can take to the bank. Generally speaking the more pitch the more speed. But sooner or later you will bog the engine down with more pitch than it can handle. Diameter generally speaking will control RPM. But also the bigger the diameter the bigger the piece of air it grabs. But the bigger the diameter the harder (slower) to turn. Thrust is a combination of all three prop variables-rpm, pitch, and diameter.

Prop testing can get expensive in a hurry when you are working with the bigger props. I have attached a picture of the results of some testing I did on a Super Tigre 90 (2 stroke) that had about a half gallon of home brew 80% methanol and 20%caster oil run through it before this test began. The same fuel was used for the test by the way. This is what I am running in all my engines.For a short video that shows the test stand I built and how it works check out this link:
http://www.rcuvideos.com/video/Engin...-02-11-2009-WM

Also there is an old write up/review on Super tigres website- http://www.supertigre.com/engines/supg0235-man.html
That makes mention of swinging the bigger props with this engine.

Make no mistake my test are static. That only gives some use full info. Different engines are different and different planes change the effects as well. Once the plane is in the air and at speed with the prop somewhat unloaded things change once again.

In an “on the plane” test with my STt90 on a 9lb plane comparing the 15X6 to the 16X4wide here is what I noticed. The 15X6 pulls the plane solid goes vertical with authority. Now I am not a 3D pilot at this stage of the game so take this for what it is worth. With the 15X6 to hang it on the prop I must back of to around half throttle or a little more. When I get the plane to hang there... The prop eventually stalls out (you can tell by the sound and RPM) the plane flops over and I get to start over. With the 16X4wide I can hang it on the prop it takes almost full throttle and it will hang there as long as I can keep it pointed in the right direction. Also with the 16X4wide the plane does fly slower at full throttle (that is to be expected) but through all maneuvers the planes speed is consistent. And on a down line with the 16X4 wide I get the very apparent prop brake action which you can tell by the sound.

I hope I did not bore you guys with this stuff. I have put a lot of time into prop test and this is the first time I have tried to share it with anyone. I hope it some how helps you with your prop experiments and selections.

cmoulder

No, I understand you are a "Right Thruster" as well.

It just puzzles me how some people can deny something that is totally supported by so much scientific proof and practical experience. It's like someone saying he doesn't believe in gravity. We (well, those of you more knowledgeable than I) can debate the various factors that influence how much right thrust might be desired, but to debate its existence is absurd.

You are right to walk away from those arguments!

russmhunt

check

russmhunt

ok i'm gonna change the subject real quick how do you clamp the little clevis over the pull pull rudder system is there a special way to clamp around the wire i have a pair of needle nost pliers but thought i would be safe than sorry here is the firewall pics and notice the landing gear skirts the red never touched the red trim so i got a blue "" you'll never see that different blue in the sky the other side lined up

cmoulder

Russ, there should be some little brass tube sections (about 1/8" long) and you simply loop the pull-pull wire through them and then loop the tail end of the wire through again and pull it snug, then crimp it with some needlenose pliers to set it.

Your photos look like you're doing a good job. There is some engine offset, which is good... I don't know how much but it looks pretty close. You need to drill another hole for the throttle linkage, so just temporarily mount the engine and use a section of control rod or something like that (maybe a long screwdriver) to make a straight line from the throttle arm back to the firewall and drill a hole there.

The photo shows the throttle linkage for the OS 1.20 4-stroke on my Venus II. The carb of a 4-stroke is a LOT closer to the firewall than the carb of a 2-stroke, so you will have a little more wiggle room to work with.

cmoulder

Rick, one of the many tricks I have learned from gassers is to use a washer under the screw head of ball links. That way the plastic outer part cannot pop off the ball, and even if it wears badly, you will still be able to fly the plane.

The photo below shows the washer on a ball link (at the servo end) and also one of the threaded fittings where a carbon fiber rod is glued into the end. A lot of guys just glue them in with CA or epoxy or JB Weld, but I have had them come off so I drill a hole through the fitting and the rod, then back up the glue with a 2-56 bolt and nylock nut. That sucker ain't goin' nowhere!

russmhunt

here is the finished motor area the throttle pushrod rests on the muffler base but still moves freely i tried to think of the best way possible but the tank prevented me from going down the middle did a test start this morning and this baby runs smoothly had a little smoke coming from the glow plug but it just needed tightened gonna do the throttle servo and rudder servo and cut the cowl today then weight her and do a test drive down the road still to muddy to fly here we been hammered with thunderstorms all week

cmoulder

Lookin' good![sm=thumbup.gif]

But you MUST keep the throttle pushrod from touching the muffler. Metal-on-metal causes RFI which can lead to MAJOR control glitches.

russmhunt

where is the cg at book says 120mm but i didn't go to college whats that in inches

JackMcAfee

There are 25.4 mm per inch
So 120 mm equals 4.73 inches

russmhunt

another question this one has me stumped the easy fuel fueler i know one tip goes to the tank and it says the other goes to the carburator but the carb is hooked up to the needle valve what gives here. this is holding me up,anyone got pics or references to go off of or how to go about hooking this "easy" fuel filler up

min$2crash

RICKSTUBBZ wrote: "So that we are on the same page and understand that we are on the same side of the thrust fence please re-read what I wrote in post 745.....
"

Hey, hey, hey now- lets not be puttin' up any fences here. I straddle the issue, meaning I've gone both ways. If you go puttin' up a fence, I will experience pain... well.... THERE! My first 5 or 10 always had right and down. As I learned to hover, I found the engine side thrust to reduce my workload. Then I decided to start using the rudder more, so I reduced side thrust and started applying increasing rudder on uplines so I'd be forced to be a full-time left hand user. I also find I do better throttle management now.

APOLOGY: my recollection of 0° right thrust was from 4am april 18. I hadn't factored in the firewall tilt. I was waay past tired.
I got the engine side lighted so that I could see the engine's angle and stood up and it is clearly 1-2° right thrusted afterall. My "off to the left" observation holds for the rear but not the front of the engine, which looks very close to center. I will try Bob's excellent CF idea tonite. That tilted firewall and 45° motor orientation are conspiring to make me cross-eyed and the CF guide will help.

PS- May 9: I checked the prop tip of one blade R and L to the center of the turtledeck- 1.1 degrees right thrust.

min$2crash

russmhunt:
On a post ~1998 OS the needle is remote from the air inlet. So then you hook your fuel feed to the other tube nipple which is on the other side of the needle valve block which I recall is 90° away- see the OS manual. From what I can see in you picture, you already have the fuel line hooked up there. That means that you will need a T in that line or a third line out of the tank for your easy fueler.
If you haven't done it, it can mean drilling a nipple open on some tanks (those with molded nipples for vent), or simply running a third line ala Dubro. If you run the 3rd line put a clunk on it and you can use it for draining OR filling.

That's not Tygon tubing on a glow engine, is it? I have been told by a pretty good source that flies gassers that Tygon is NFG for glow fuel applications. Maybe Bob (cmoulder) can shed some light.

As far as the pull-pull crimps, I find the $7 crimping pliers used with crimp electrical fittings (auto parts, Home Depot) work great. Lots of leverage, nice small patch of crimp but it won't CUT the crimp tube. I use the bumps between the cups... which only makes sense if you own one. Maybe I'll pony up and post a pic tonite.

Last but not least, I'm very jealous: your Pitts is gonna look awesome.

cmoulder

Russ, it goes to the needle valve. Back in the dark ages the needle valve was located ON the carb.

russmhunt

alright guys look closely i do have a third nipple coming out of the tank that goes to the easy filler but the easy filler has 2 nipples so my carb is hooked to the needle valve so i guess i need to buy a t ??? to split the card and needle valve to hook up the easy filler the other 2 pics are of the cowl i cut 1 3/4 inches off the rear and the red trim lined up pretty good

russmhunt

quick reply to my self can i just block off one nipple on the easy filler why do i need one going to the carb if its job is to just be a supply to fill the gas tank and how do you know when the tank is full if the cowl is on and the hatch is bolted down

PMAXX

My Feedback: (5)

You only need 2 lines from your tank when using the ez filler. Vent line to the muffler and the second line will go to the angled nipple on the ez filler, then from the straight nipple of the ez filler to the needle valve assembly. You can use the third line as an overflow when the tank is full since its allready there. I usually put a small jar under the exhaust pipe to catch the overflow. Hope this helps.

PMAXX

My Feedback: (5)

P.S. When you insert the nipple to fule up the ez filler diverts the fuel to the tank. When you remove the filling nipple your engine will draw fuel through the ez filler. You can also drain your tank through the ez filler. They work quite well, I've used them a few times.

russmhunt

thanks i got it working now damn this been bogging down my finishing all day thanks for the input i do have the 3rd nipple in the tank i'll just route it out the bottom of the plane for a overflow line this plane is fu-kin crazy fast on asphalt i'm gonna keep my throws way low till i get the hang of her that ole ass kept wantin to come up at 1/4 throttle got squirrely in the road and now i know what you guys mean about cheap landing gear that bunk ass aluminum caved in a little i noticed it when the plane was sitting lopsided so i straighted it out and am for sure going to put carbon fiber landing gear on cmoulder i did reroute the throttle rod and it is not rubbing any more and was actually better the throttle rod does not bend any more when moving the servo i do believe mine is nose heavy so where have you guys been putting you cg mark at and i know at 120mm and i know it is like 4 and some weird crap numbers but i need likeexample 4 and 5/8 numerals not 4 and 2.346<- this will not read out on a tape measure

cmoulder

CG of 4-3/4" to 5" will work just fine.

No need at all for a third line in the tank. Overflow will drip out your muffler, which is absolutely okay.

Hold in a LITTLE right rudder when you throttle up for the take-off roll and gradually relax the rudder as the plane builds up speed and the take-off run will be straight.

Get some altitude quickly and then throttle back to about 1/2 throttle and trim the plane. Make sure you use a neck strap so there is something to support the Tx while you reach over and adjust the trims.

russmhunt

what should i do with the 3rd nipple in the tank it was already there epoxy????

cmoulder

Put a small piece of fuel tube over it and plug the fuel tube.

Russ, once you get finished and are ready to maiden, don't get in too big of a rush. Take the plane to your local club field and have someone with a lot of experience go through a checklist with you. The person you select should be someone who regularly takes off and lands without incident, and who flies in a calm, controlled manner. Have him stand by you as you maiden, or even maiden the plane for you and get it trimmed.

After all the work you've put into this, we all want to see everything go well for you.

Here is the Great Planes checklist, which is pretty good. It has saved my bacon a couple of times, and I still use it all the time.

❏ 1. Fuelproof all areas exposed to fuel or exhaust
residue such as the wing saddle area, the wing
mounting tabs, etc.
❏ 2. Check the C.G. according to the measurements
provided in the manual.
❏ 3. Be certain the battery and receiver are securely
mounted. Simply stuffing them into place with foam
rubber is not sufficient.
❏ 4. Extend your receiver antenna into the antenna tube
inside the fuselage.
❏ 5. Balance your model laterally as explained in
the instructions.
❏ 6. Use threadlocking compound to secure critical
fasteners such as the set screws on the wheel
collars, screws that hold the carburetor arm (if
applicable), screw-lock pushrod connectors, etc.
❏ 7. Add a drop of oil to the axles so the wheels will
turn freely.
❏ 8. Make sure all hinges are securely glued in place.
❏ 9. Reinforce holes for wood screws with thin CA where
appropriate (servo mounting screws, cowl mounting
screws, etc.).
❏ 10. Confirm that all controls operate in the correct direction
and the throws are set up according to the manual.
❏ 11. Make sure there are silicone retainers on all the
clevises and that all servo arms are secured to the
servos with the screws included with your radio.
❏ 12. Secure connections between servo wires and Yconnectors
or servo extensions, and the connection
between your battery pack and the on/off switch with
vinyl tape, heat shrink tubing or special clips suitable
for that purpose.
❏ 13. Make sure the fuel lines are connected and are
not kinked.
❏ 14. Balance your propeller (and spare propellers).
❏ 15. Tighten the propeller nut and spinner.
❏ 16. Place your name, address, AMA number and
telephone number on or inside your model.
❏ 17. Cycle your receiver battery pack (if necessary) and
make sure it is fully charged.
❏ 18. If you wish to photograph your model, do so before
your first flight.
❏ 19. Range check your radio when you get to the flying field.
The Venus II ARF is a great-flying model that flies smoothly
and predictably. It does not, however, possess the selfrecovery
characteristics of a primary R/C trainer and should
be flown only by experienced R/C pilots.

russmhunt

well here is my finished product all i need to do now is get a t pin for the receiver antenna i took mine out the top instead of the bottom and ca the fiberglass screws i got the tank mounting idea from someone else on here plus it looks good and i mounted the battery under the mount in the rear and good thing i bumped it it was not even glued in 5min epoxy fixed that little problem set my throws to recommended setting gonna take it to the field and have her looked over but i am gonna maiden it, if it goes down i want to be the one to do it

nicov1978

Hey Guys,

I tried the 13x8. I had more speed, it is better for aerobatics. It worked well... but no longer does my dear Extra... I crashed it... Think I'll buy another one.

For those who ever had a throttle cut, how did the plane behave? Well or unsteady? Still behaving well and steady at low speed or starting getting unsteady at low speed yet still higher than lower speed you usualy land?

Thanks guys,

Nicolas

cmoulder

Nicov, sorry to hear about that![&o]

That happened to my first one, with some kind of radio lockout during a loop... it did 3 more big loops by itself, with the last loop finishing in the weeds and dirt.

But this is such a great-flying model that I also went out and got another right away and was flying it 2 weeks after the original crashed.

One thing to remember on deadsticks is that when any plane's engine quits, you're now flying a glider, and you're now tasked with an energy management exercise. The plane has the same stall speed whether or not the engine is running, but you don't have that little bit of additional thrust when the engine is idling, so you have to keep the nose down a little extra (to keep the speed up) until you are ready to make a normal flare to land. One mistake I see guys make (and one I used to make!) was to start flaring too early, leading to a stall several feet off the ground, followed by a crunch. The basic thing I always repeat to myself now is "LET IT DOWN".