bob27s

My Feedback: (19)

Marty,

I just wanted to follow up on this a bit. Im pretty sure Dub had the engine sent back to you before the Hurricane stuff occured.

Was running real well on the bench.

Bob

afterburner

My Feedback: (18)

Yes Bob,
I received the engine yesterday and re-installed it in the plane. I re-plumbed the tank and moved it back a bit so I could get more foam on all six sides. I ran one tank in the backyard today in the plane. Was peaking at about 16.2 /16.3K with an APC 10 X 6. It ran very stable at WOT only varying 100 to 200 RPM. It ran for about four to five minutes and I shut it down. There wasn't much fuel left in the tank. There were no bubbles in the line so it should be good to go. Will set it four to five hundred RPM below peak and see how it goes. I might be able to try it out tommorow and will post as soon after. Thanks for all the help. How did Jett Engineering weather the storm?

Marty

bob27s

My Feedback: (19)

Storm wasnt much according to Dub. Just the power went out for a while.

afterburner

My Feedback: (18)

Well, I flew the plane today and I'm still in the same situation as before the engine came back. Ran it with the 10 x 6 and peaked about 16.3K. Backed it down to about 15.7 and shut it down. Topped off the tank and restarted checked peak at 15.7 and flew. The engine didn't seem to sag in flight but the speed just was not there. It seemed to be about the same as with the O.S. ? The next time I fueled it up and ran it to peak and backed off about 500. Let it cool and topped it off. Went to start and the plug was shot. It looked brand new which it was. Replaced plug and retuned and flew. No change. Put a 9 x 7.5 and that peaked up in the 16.7 range. Backed that off 500 and flew. Just about the same as the 10 x 6. It must still be leaning out in the air is all I could figure? How far can the tank be moved back from the engine before there is a problem? If I can move it further back, I can probably get some more foam to insulate. I'm not even sure if that's the problem.


Marty

smitty9969

My Feedback: (7)

Alot of times with Jett's it's better to run what u think might be rich on the ground to allow it to unload in the air.. especially if you burnt up a plug.. what i like doing its setting the needle so that i can hear it come up on the pipe and check for smoke.. Smoke tells me its still rich. I went to a qm40 race and noticed that all the planes on the ground were still smoking but didnt so much in the air.. Also Ive noticed that while setting the needle, it wont cut out while running lean.. I can keep turning the needle and the engine keeps running, but the rpm's stay basically the same.. But when i back it off it sounds alot better and sometimes even pick up a few more rpms..
Long story short.. i think your running it too lean..

js3

My Feedback: (3)

Yes, yes, yes! My experience exactly.

afterburner

My Feedback: (18)

I will try backing it off even more on my next outing and see if that helps.

bob27s

My Feedback: (19)

plugs blow for one reason - lean run somewhere along the way. Try backing down a bit more. See if that helps.

Your peak rpm is about correct. With the extension in there, its giving up 600-800 rpm off the top. It turned 17K on the bench with a 10x6 without it.

Fly it with the 9x7.5 for a few flights. Let it run in a bit. Its a bit tight. That is ok, just give it a few runs. You can take advantage of the longer pipe length due to the extension by using more prop. 10x7, 9x9. Go up in pitch for more speed. The std blade 9x9 works well on the patriot.

If it runs ok on the ground, and then goes lean in the air, 95% of the time --- yep -- foam.

Confirm the fuel system first. You can move the tank aft about 4 to 5 inches from its stock location and you will be ok. The other alternate is installing a bubble-free fuel system.

Keep in mind, the Patriot is not an extremely fast plane. But you should see some improvement.

afterburner

My Feedback: (18)

I moved the tank to just in front of the wing former and pulled out some of the 1/2" foam. Dub had emailed me about using 1/2" all around but I think by jamming in the 1/2" in some tight spots, I was defeating the purpose of the foam. Now the tank has a little play.

I brought the RPM down about 800+ from peak and flew with the 9 x 7.5 and the flight went well. Made three flights in all and things seem ok. The last flight was with a 9 x 8.5. Hopefully will be able to try the 9 x 9 soon.

The only thing that has me still wondering is that I'm getting about four to five minutes at full throttle and then I hear a slight hiccup like she's running out of fuel so I immediately bring the throttle down and drop the gear and land. There seems to still be a fair amount of fuel in the tank. Probably about a third. The tank has a 10.8 oz. capacity. I know the instructions say to never fly below a 1/4 of a tank so maybe this is normal.

Marty

bob27s

My Feedback: (19)

Hi Marty,

sounds like things are going ok.

Good call on the flight there... it is always good to be safe.

Yes, consider that last 1/4 tank "un-usable" fuel. Basically a 10 oz tank is good for 8oz of usable fuel, with 7 oz of safe flyable fuel. The clunk bounces around a bit under most circumstances - and that little burp of air as the clunk jumps clear of the liquid fuel a bit is what you are hearing. The engine burns about 1.25 oz per minute at full song, so typically you should get 5-6 minutes at 100% throttle. I think with time and the refinements you have made, you will see 6+ minute flight times.

The bubble-jett and tetra tanks help avoid 99% of fuel problems, and because there is no risk of air bubble, you can burn 100% of the tank capacity. Sometimes switching to one of those can get you more flight time in the same available space.

For QM40 and Q-500, we have found bubble-free tanks pretty much mandatory. The QM40 engines burn through a 6oz tank in about 3 minutes