stunthanger.com
Engine basics => Engine set up tips => Topic started by: Bill Hummel on November 27, 2022, 04:30:45 PM
-
Looking for someone who flies a Brodak 40 with .280 venturi and stock NVA; how much fuel to fly the pattern? Trying to plan for tank size on new build. Thanks for any help with this!
-
Looking for someone who flies a Brodak 40 with .280 venturi and stock NVA; how much fuel to fly the pattern? Trying to plan for tank size on new build. Thanks for any help with this!
Hi Bill;
A stock Brodak .40 , when new or low time, can be a pretty thirsty animal if running 10%. I would plan on at least a 5 ounce tank. They get better as they get more time on them but it does take a while. My first experience with them was when they first came out. I have a profile model that I was running a FP-.40 on with a 4 ounce tank, and just switched engines. I went to the SIG contest with it and didn't get a chance to test fly it at all, and imagine my surprise when it ran out of fuel ( a full 4 ounces) at the overhead 8's!! I think I was able to stuff a 6 ounce plastic tank on it that worked well right off the bat and is still on the airplane. If there is room for a 6 ounce Sullivan RST tank, I would go that route so you know you will have plenty. Other wise see if there are any 5 ounce metal tanks on the market or fabricate one.
Good luck with it!
Type at you later,
Dan McEntee
-
I ran my Brodak 40 on 4 1/2 ounce tank. Usually got 5 to 10 laps after the clover. No extra laps between maneuvers.
-
I had trouble with the stock NVA assembly. I could not get enough pinch to secure the needle from rotating due to vibration. I replaced it with an ST unit but that should make no difference as the spraybar diameters are the same.
I am using a .290 venturi and I never needed more than 5% nitro. In cooler weather, 2% is good enough. My fuel consumption with those two nitro percentages varies from 3.5 ounces to almost 4. I am using the supplied tube muffler. I get about a minute of run time after the clover.
This particular Brodak 40 does not have hundreds of flights on it but it is fairly well broken in.
-
I had trouble with the stock NVA assembly. I could not get enough pinch to secure the needle from rotating due to vibration. I replaced it with an ST unit but that should make no difference as the spraybar diameters are the same.
I am using a .290 venturi and I never needed more than 5% nitro. In cooler weather, 2% is good enough. My fuel consumption with those two nitro percentages varies from 3.5 ounces to almost 4. I am using the supplied tube muffler. I get about a minute of run time after the clover.
This particular Brodak 40 does not have hundreds of flights on it but it is fairly well broken in.
Hi Jim;
I have had that issue with other ST type needle valve assemblies. Take the NVA apart and examine the threaded end. Sometimes the slot isn't cut deep enough or wide enough and needs to be touched up. I have also had to improve the bevel on the end that the nut picks up to pinch the end against the needle. Some of the after market ST needles out there will do this also.
Type at you later,
Dan McEntee
-
The Brodak 40 is a great engine! It will easily pull a 50oz plane through the patten with a 4-2-4 break. 59'.015 lines, Powermaster GMA 10-22 fuel, must be filtered before you put it in the tank. APC 11.5x4 prop, 4.5oz tank, Sig or Thunder bolt idle bar plug, Stock NVA & Venturi with 1- or 2-pieces of pantyhose covering the Venturi. Make sure you have a later Brodak muffler that has at least a .360 exhaust opening. A Fox 40 downward style muffler works great on upright engine setup.
Al
-
Bill
if you want to go with the ST style NVA, use one of these from Bobby in Florida.
Enya makes them for him.
I use these on my LA and other engines and they work great. No fiddling needed.
Carl
https://www.ebay.com/itm/293689069208?hash=item44613b8e98:g:Z5UAAOSwTdpfNV8r
https://www.ebay.com/itm/294513244851?hash=item44925b7ab3:g:F3wAAOSw9BlhcyUs
-
I had trouble with the stock NVA assembly. I could not get enough pinch to secure the needle from rotating due to vibration.
That sometimes happens with the original ST spraybar as well. The problem was that the brass wore/flowed enough that the slot in the collet end of the spraybar close up all the way, so it was tightening on itself and not squeezing the needle. The fix was to take a razor saw, and open up the slot (cleaning out the chips afterward).
No guarantees, but worth a look. A lot of the off-brand ST copies have various machining issues that make the not work or unreliable.
Brett
-
My Brodak 40 consumed about 110 cm3 of fuel with 10% nitromethane per complex.
-
Thanks, guys, lots of good info!
-
OT, but who makes Brodak .40's these days? I know Double Star (aka "2 Star") made them originally, and for awhile, but DS apparently went out of business some years ago. Sadly, I might add. I like my DS .60bb ABC.
I'd also like to know whose genius idea was it to sell the pistons and cylinders seperately, so you don't know if the piston will even go into the cylinder bore? Or, has that sillyness been rectified? R%%%% Steve