What prop for OS .46 w/ Viper 500?
03-08-2014, 07:09 PM
#28
Interesting. I wonder what the carb barrel looks like in that engine? By that I mean is it kinda small? One of the big mods we always did to the FP series wa to go up to the next sized barrel. So on the .25 FP, we would stick in a .40 FP barrel. This really improved performance. On that engine it was at least 500 rpm, maybe 1,000. If you get to where you are chasing speed, you might lok to see if the .60 sized LA barrel will fit your carb. I am just guessing here though, as I have no experience with the LA series. Small venturi sizes is a trick they pull on those sport engines to get them to draw fuel better. Good for the newbies I guess! lol
03-10-2014, 08:15 AM
#30
Thread Starter
Maiden flight was fairly successful. Take off from the grass was excellent, so I flew a couple of circuits.
My aileron authority was bare minimum, which was a little uncomfortable, but manageable. I didn't bother to switch to high rates, as elevator authority was quite acceptable.
She wanted to dive, so I began adding up trim, but I think the tail needs a slight incidence angle decrease.
A buddy said "She's running lean" so I came in for a landing, which was one of those "plane doesn't want to land" jobs. But I was patient and let the plane come down waaaay over there, which was fine, but then at the very last she hit a bump and did a little cartwheel.
No damage except for a nice crack just in front the V-tail. Wah. I hate to do the "de-fueling of shame" when the very first tank is nearly full! Arg!
She'll fly much better next week.
My aileron authority was bare minimum, which was a little uncomfortable, but manageable. I didn't bother to switch to high rates, as elevator authority was quite acceptable.
She wanted to dive, so I began adding up trim, but I think the tail needs a slight incidence angle decrease.
A buddy said "She's running lean" so I came in for a landing, which was one of those "plane doesn't want to land" jobs. But I was patient and let the plane come down waaaay over there, which was fine, but then at the very last she hit a bump and did a little cartwheel.
No damage except for a nice crack just in front the V-tail. Wah. I hate to do the "de-fueling of shame" when the very first tank is nearly full! Arg!
She'll fly much better next week.
03-11-2014, 09:22 AM
#31
Yes these airplane want to really float. it would be worse if you are nose heavy. Those wheels are forward of the CG. Given the surface you are flying from and the additional drag you may want to try a 10X5 prop. Ill try to get out this Sunday and if I do you are welcome to try some of my 20% fuel too. just about every race airplane I have flown lands better with slightly higher rates then what is used to fly.
03-11-2014, 01:29 PM
#32
Thread Starter
Excellent! I look forward to it! My CG was spot on at 3" as per the manual, but I set my battery back a bit to get to 3 3/4", hoping for easier landings. That first landing should have been waved off but my buddy said "lean" and I didn't want to damage my engine... I'll be better lined up next time, and when I put the tail back on, it will have been checked with an incidence meter (borrowed from Mike).
03-17-2014, 08:03 AM
#36
Thread Starter
Yay I finally got to fly the Viper and meet speedracerntrixie on Sunday! Thanks for the tips! After you left, I did 3 more flights. I continued with the 9x7 as we couldn't find another to try. The engine seemed to do better each time - it seems to be breaking in nicely, and generating less heat.
I need to nail down a couple of quirks though. The engine mounting screws, all 8 of them, kept coming loose. I think I am going to JB-weld the inside ones in, as that gets tiring fast. The outer bolts seemed fine after tightening them when the engine was warm.
Also, the wing mounting bolts were coming loose. I may convert them to 1/4" nylon but for now I will just check them after each flight, no biggie.
I increased the aileron travel as much as possible and the roll authority is still minimal. Playing with the detached wing in hand, I could feel it really "fight the roll". With practice, I can manage it.
I re-measured the CG at about 3 1/3 inches, which felt just fine. My final landing of the day was best, and managed a nice flare and graceful touchdown. Those big wheels saved the day twice from gopher holes and dirt mounds. No broken props and 2 landings finished with the engine still running.
I've got some 9x6 props on the way, including a couple wooden ones to try. It may be a while before I get more flying time though, I think my next 2 weekends are booked up... wah.
I need to nail down a couple of quirks though. The engine mounting screws, all 8 of them, kept coming loose. I think I am going to JB-weld the inside ones in, as that gets tiring fast. The outer bolts seemed fine after tightening them when the engine was warm.
Also, the wing mounting bolts were coming loose. I may convert them to 1/4" nylon but for now I will just check them after each flight, no biggie.
I increased the aileron travel as much as possible and the roll authority is still minimal. Playing with the detached wing in hand, I could feel it really "fight the roll". With practice, I can manage it.
I re-measured the CG at about 3 1/3 inches, which felt just fine. My final landing of the day was best, and managed a nice flare and graceful touchdown. Those big wheels saved the day twice from gopher holes and dirt mounds. No broken props and 2 landings finished with the engine still running.
I've got some 9x6 props on the way, including a couple wooden ones to try. It may be a while before I get more flying time though, I think my next 2 weekends are booked up... wah.
Last edited by markind; 03-17-2014 at 08:09 AM.
03-17-2014, 09:55 AM
#37
Mark, I thought I saw the engine bounce a little but wasn't sure. The 9X6 will really help and you will actually go faster. That LA just doesn't have the power to spin a 9X7. As your engine breaks in with the 9X6 you will gain more speed and the ailerons will get more effective. If you ever feel the need to get it going any faster used 40-46 size engines are easy to find and are pretty darned cheap. A piece of vinyl tape over the wing hold down screws will keep them secure or changing them over to 1/4" nylon is a good idea as well.
03-24-2014, 08:08 AM
#39
Thread Starter
Finally some good Viper flying
Yay! Sunday was perfect, and I got 'er all trimmed out so she flies thumbs-free.
The first prop I tried was a MAS 9x6, but it was defective, and even after balancing, wobbled terribly. It was warped or something...
So I went to an APC 9x6 and flew 3 times, all on rich setting. I was testing flying at idle and enjoyed the excellent glide, but when I went to half throttle, the engine bogged and quit (too rich). I had *just* enough altitude to pull off an excellent emergency landing though. Whoo, that was fun!
Those big wheels work great on the rough terrain and I had two further perfect landings with the engine still running. Sweet! I just need to practice more - the only trick I can do is loop, hehe
Oh check out the new bling - I had fun and it turned out great!
The first prop I tried was a MAS 9x6, but it was defective, and even after balancing, wobbled terribly. It was warped or something...
So I went to an APC 9x6 and flew 3 times, all on rich setting. I was testing flying at idle and enjoyed the excellent glide, but when I went to half throttle, the engine bogged and quit (too rich). I had *just* enough altitude to pull off an excellent emergency landing though. Whoo, that was fun!
Those big wheels work great on the rough terrain and I had two further perfect landings with the engine still running. Sweet! I just need to practice more - the only trick I can do is loop, hehe
Oh check out the new bling - I had fun and it turned out great!
04-02-2014, 12:44 PM
#41
Thread Starter
I put up a short Viper Vid:
http://youtu.be/drZpI1cT740
Only 2 min. - worth a chuckle
http://youtu.be/drZpI1cT740
http://youtu.be/drZpI1cT740
Only 2 min. - worth a chuckle
http://youtu.be/drZpI1cT740
04-04-2014, 10:29 AM
#43
Thread Starter
I may not be able to fly this Sunday, but the weather will be excellent and Mike will be out there for sure.
That engine is still breaking in so I have been running it way on the rich side, and I'm only running 10% nitro. I still have a couple gallons of 10% I am trying to burn through...
Btw our days at that open field are indeed numbered! They just installed major sewer lines around the perimeter...
That engine is still breaking in so I have been running it way on the rich side, and I'm only running 10% nitro. I still have a couple gallons of 10% I am trying to burn through...
Btw our days at that open field are indeed numbered! They just installed major sewer lines around the perimeter...
