What prop size
08-23-2014, 05:37 PM
#1
What prop size
Guys, Been looking for the right prop for Viper500 with TT40-I tried to open the past threads in sticky section but they would not open. What prop do I need to run on this-thanks in advance for your replies-by the way it does have a stock muffler on it.
08-23-2014, 06:49 PM
#2
Jim, This is a pretty simple choice. If you are racing the AMA 424 event you may only run the APC 9/6. This is the universally approved prop. If you are flying for fun, start with the APC 9/6 and then experiment. A strong TT Pro 40 on the latest, and greatest quickie 500 air frame with the 9/6 APC should do about 115mph. Your Viper is a 20 year old design, so it might be a little slower. Don't expect top performance from a new TT Pro. Most of them need a lot of running. There has been a lot of information on this Forum, and others, about legal changes that can be made to the TT Pro for AMA 424 racing. Probably the most important is to replace the bearings, which are known to disintegrate. In fact most of the approved changes are not meant to improve performance, but rather to improve reliability. Good luck, Greg
08-24-2014, 06:34 AM
#4
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What prop size
The 9 x 6 APC is the official race propeller.
For break-in a smaller propeller that lets the engine rev-up is best. I've used a 9 x 4 APC and 8 x 6 APC with equally good results.
All of my engines were the newer generation. You don't need to change out bearings on the newer engines. The bearings seem to hold up fine. In my experience you do need to let the engine turn up during break-in for best results.
For break-in a smaller propeller that lets the engine rev-up is best. I've used a 9 x 4 APC and 8 x 6 APC with equally good results.
All of my engines were the newer generation. You don't need to change out bearings on the newer engines. The bearings seem to hold up fine. In my experience you do need to let the engine turn up during break-in for best results.
08-24-2014, 09:14 AM
#6
Sahartman, I've had a plastic retainer on the new TT bearings fail and destroy a piston. A set of stainless front and rear bearings can be had from RC Bearings for around $12.00 including shipping. I just ordered two sets, and the prices went down! Go figure? Speaking of the newer generation engines versus the older generation. A lot of us feel the the older engines out perform the newer ones, so always keep an eye out at swap meets for used TT Pro 40's. Don't search so much for the older carburetor (straight needle valve), but look at the cooling fins on the crankcase. The fins on the older engines are not machined. The fins on the newer engines are machined. Often the color of the older engines is gray, compared to a brighter silver on the new engines. This is only speculation, but we believe the changes came about when they stopped production in Taiwan, and moved it to mainland China. Quality may have also suffered? Good luck, Greg
08-30-2014, 04:10 PM
#9
I am not real current in 424 but do suggest doing as Kurt is suggesting and concerning that last phrase about the mufflers, Here is the final answer to the lost muffler cone drama having tried all the traditional methods of keeping the darn thing on.
I just got frustrated, took a couple brand new mufflers with the baffles in place, unmodified to a professional job shop and had them welded. This made them illegal so the procedure was simply to do all practice flying and even early morning needle flights at an away field with them installed and it was a simple matter to install a non welded pipe before tech inspection and the races.
I never had to buy a new muffler agine. Here they are on a pair of new TT's, just last week on a Club Forty and an old Racer 11. I keep getting dragged back kicking and screaming to this stuff by the fellows
