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Q-500 Racing Discuss AMA 428, AMA 424, and any other variants of Quickie 500 racing

Engine for pylon training

Old 10-13-2020, 05:31 PM
  #26  
elmshoot
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Dub Jett model aircraft - Bubble-Jett fuel tanks and accessories

Two or three fills and you will be good togo.
Any idea what RPM you are turning? also what is you time on course?
Sparky
Old 10-13-2020, 08:13 PM
  #27  
GREG DOE
 
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Whiskey 29. What Elmshoot has said in the previous post is to use a plunger type syringe to fill the bladder tank. Evacuate all the air from the tank with the syringe, and then pump in an ounce or two of fuel. Then evacuate that fuel and some more air will come with the fuel. It is recommended that you do this a minimum of three times to be certain that all but a few air bubbles have been removed from the tank. It is important that you remove as much air as possible. Dub Jett sells a "tankard" for fueling, and most of us use his syringe. It includes a good set of instructions. I have a animal medical syringe that I purchased from Tractor Supply that I keep in my tool box for emergencies, like when I forget my tankard! It only has a 2 or 3 oz. capacity so it takes several fills to fill up a Quickie tank. The other thing is you are going to want some kind of a clamp on the fuel line to keep the bladder from flooding your engine. Some of us use medical clamps like the kind that are used on IV systems, Home Depot has a small clamp, and some folks use hemostats.
Old 10-14-2020, 04:23 AM
  #28  
whiskey29
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Sparky, thanks for the link, I have seen that before too
I was going to try 50cc animal syringe.
the engine turning 15.5k with 9x75, my best lap was 103 secs (in the morning) while national ran mid 90s,

Greg thanks for the hemostats tips
by the way, if I use bubble-less tank, can I mount the tan kat cg (under wing) instead of behind firewall?

Last edited by whiskey29; 10-14-2020 at 04:47 AM.
Old 10-14-2020, 04:50 AM
  #29  
elmshoot
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Whiskey,
Can you post a picture of your race planes? It sounds like you are flying a 424 like airplane based on time and distance flown. Do you race head to head (first one to the finish line is the winner regardless of time) or is it more like FAI and time is used for winners.
Sparky
Old 10-14-2020, 12:06 PM
  #30  
GREG DOE
 
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Whisky, To answer your question ,another advantage is that you can, within reason, mount your fuel tank almost anywhere in your airplane. Many of the modelers racing the Q40 event, for example, locate their tanks on the center of gravity, so that there isn't a trim change as the fuel is burned.
Old 10-17-2020, 06:16 AM
  #31  
whiskey29
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Sparky, I will take some pics tomorrow.
we race FAI and use time.

Greg, is it just my feeling that I don't really feel the trim change towards the end of the flight.
Old 10-17-2020, 12:13 PM
  #32  
GREG DOE
 
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Whisky, Tough question? With the tank on the CG it's possible to move the airplane's CG further back. A more rearward CG will allow the airplane to turn with less elevator throw to accomplish the same turn radius, so the airplane doesn't slow down as much in the turn with the more rearward CG. The conventional CG location for an airplane with the tank behind the firewall might get too sensitive as the fuel burns off. The two pluses with bladder tanks is that you can set the needle valve much closer to peak RPM, and the tank can be located further from the engine.
Old Yesterday, 05:46 AM
  #33  
whiskey29
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Originally Posted by GREG DOE View Post
Whisky, Tough question? With the tank on the CG it's possible to move the airplane's CG further back. A more rearward CG will allow the airplane to turn with less elevator throw to accomplish the same turn radius, so the airplane doesn't slow down as much in the turn with the more rearward CG. The conventional CG location for an airplane with the tank behind the firewall might get too sensitive as the fuel burns off. The two pluses with bladder tanks is that you can set the needle valve much closer to peak RPM, and the tank can be located further from the engine.
noted Greg.

attached are what friends here are using.
The yellow no 4. Is mine to fly, given by a friend that lives in other city, its running abuse able os.46 fx with 50ish muffler, not legal, just for practicing. That engine RPM gets close to OS .46AX

I have a seeker as well, currently finishing other two. I uploaded pic the plane on Shartman posts a long while ago




Old Yesterday, 04:30 PM
  #34  
elmshoot
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Looks similar to our 424 race class.
Can you select the props? I think you are spending more time straight than we are. Top speed would be a little more important. I know a 10.5x 4.5 narrow blade prop is faster than a 9x6.
Sparky

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