Byron Cap 21, ST 3000, which prop?
11-23-2005, 10:25 PM
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Byron Cap 21, ST 3000, which prop?
I am finishing a Byron Cap 21 with a St 3000 in it. Which props are suggested for it? I prefer power over speed.
Also I can go with gas on it if I want as I have the stuff for it. Just need the proper carb.
Thanks for any info.
Also I can go with gas on it if I want as I have the stuff for it. Just need the proper carb.
Thanks for any info.
11-23-2005, 11:56 PM
#2
RE: Byron Cap 21, ST 3000, which prop?
3 choices--as I see it. 18-10 or a 19-8 or a 20-6.
The engine will swing any of these props with plenty of grunt.
Prop it for about 7000--7300RPM on the ground. This engine makes it's best power at 7900RPM.
Keep the nitro at 10% or less. I used 5% in mine. You can drop the oil down if you want, but I never had a problem using 5% Omega fuel.
If you have problems with midrange gurgle and loading up--don't fight it. Just replace the carb with an OS7D carb and you'll be much happier.
If you can get it to run right on the stock ST carb--then your smarter than most guys. I never could get it figured out.
The engine will swing any of these props with plenty of grunt.
Prop it for about 7000--7300RPM on the ground. This engine makes it's best power at 7900RPM.
Keep the nitro at 10% or less. I used 5% in mine. You can drop the oil down if you want, but I never had a problem using 5% Omega fuel.
If you have problems with midrange gurgle and loading up--don't fight it. Just replace the carb with an OS7D carb and you'll be much happier.
If you can get it to run right on the stock ST carb--then your smarter than most guys. I never could get it figured out.
11-24-2005, 12:07 PM
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RE: Byron Cap 21, ST 3000, which prop?
Eagle Flyer,
How much does it weigh ?
RC Pilet is right get a 7D and stop fiddling with the SupT carb.
also 5% is good that big motor does not need anymore than that.
The Bryon Cap 21 is a big Ice Chest and it flys really well but like all Caps it does not like it's
nose pointed to the ground with power on. A pull on the elevator after a bit of speed is built up
and your in for a big surprise.
On landing if you notice every time you turn on final and set up if you time it right the nose comes out level or slightly down the plane comes in and has no problems. But sometimes you don't time it right on the exit of the turn into the wind and the nose comes out a little high, when that happens the plane doesn't descend it sort of hangs there and the slower it goes the more you think any second now the nose will drop and I can get this on the ground but the plane never falls over on its nose instead it rolls over on it's back and crashes or if your close to the ground you drag a wing tip.
I have seen this happen in a 1/2 A size Cap 21 and a 40% Cap 232 makes no difference the size. What does make a difference is the speed and drag of the plane. Your question about props, that you want power rather than speed, you might want to rethink that on the Cap 21. Excessive speed is bad for a Cap 21 too little speed is bad for it too, there has to be a happy medium.
Try a prop that gives you good level speed of about 60mph at 2/3 throttle with a good idle of about 2000 or below probably around 1800 if you can. Do your pattern flying at about 1/2 to 2/3 throttle and set up for landings coming off idle up about two clicks on the throttle (about 2500 RPM) make sure you have the nose down or level when you set up for final and ride the throttle not the elevator to the runway.
You will probably see that an 18x10 will make allot of noise and not really go anywhere, the 19x8 is better maybe even a 20x8 with a 20x10 being a little doggy.
Good luck
cap10b
How much does it weigh ?
RC Pilet is right get a 7D and stop fiddling with the SupT carb.
also 5% is good that big motor does not need anymore than that.
The Bryon Cap 21 is a big Ice Chest and it flys really well but like all Caps it does not like it's
nose pointed to the ground with power on. A pull on the elevator after a bit of speed is built up
and your in for a big surprise.
On landing if you notice every time you turn on final and set up if you time it right the nose comes out level or slightly down the plane comes in and has no problems. But sometimes you don't time it right on the exit of the turn into the wind and the nose comes out a little high, when that happens the plane doesn't descend it sort of hangs there and the slower it goes the more you think any second now the nose will drop and I can get this on the ground but the plane never falls over on its nose instead it rolls over on it's back and crashes or if your close to the ground you drag a wing tip.
I have seen this happen in a 1/2 A size Cap 21 and a 40% Cap 232 makes no difference the size. What does make a difference is the speed and drag of the plane. Your question about props, that you want power rather than speed, you might want to rethink that on the Cap 21. Excessive speed is bad for a Cap 21 too little speed is bad for it too, there has to be a happy medium.
Try a prop that gives you good level speed of about 60mph at 2/3 throttle with a good idle of about 2000 or below probably around 1800 if you can. Do your pattern flying at about 1/2 to 2/3 throttle and set up for landings coming off idle up about two clicks on the throttle (about 2500 RPM) make sure you have the nose down or level when you set up for final and ride the throttle not the elevator to the runway.
You will probably see that an 18x10 will make allot of noise and not really go anywhere, the 19x8 is better maybe even a 20x8 with a 20x10 being a little doggy.
Good luck
cap10b
11-24-2005, 01:16 PM
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RE: Byron Cap 21, ST 3000, which prop?
I have the st3000 with a 20x10 masterairscrew plastic and it works good for a 18lb plane here in the denver area. a 20x8 had slightly less pull but not much. Stock carb and 15% MAGNUM FUEL.
Tony
Tony
11-26-2005, 03:55 PM
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RE: Byron Cap 21, ST 3000, which prop?
I have been running it in. Basicly it was new. Started with 20% oil, then 16%, then 8%, and now on 6%. All with 5% nitro and synthetic/castor blend 80/20. This engine has a sleeved crank pin and needle bearings on both ends of the rod. Originally had a plug that I don't know what it was. So I switched to a A3. It does real good. Except a little rich at 6000 +/- rpm. Transition is good and quick. But once in a while if let run for a long time at that 6000 # it will load up some. But it seems to be getting better so maybe it will come out of it. All I have for a prop is some 18x6 units. Using a Dynathrust 18x6 it peaks at 8300. Tried a 20x10, didn't like it. Wish I had a 18x ? to try. I do have 17x10 on another engine. Maybe that would be the one to try.
