Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Nelson q40 or 500 on 30%

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Old 04-09-2012, 03:15 PM
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Default Nelson q40 or 500 on 30%

anyone ever try to run a Nelson on high nitro?
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Old 04-09-2012, 03:36 PM
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Default RE: Nelson q40 or 500 on 30%

it can be done with right insert or shim set, the easiest way is to call henry nelson and ask for a high nitro head button and shims..
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Old 04-09-2012, 09:00 PM
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Default RE: Nelson q40 or 500 on 30%

Any idea of rpm increase from stock running 15%
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Old 04-10-2012, 12:33 AM
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Default RE: Nelson q40 or 500 on 30%

You should be looking at more prop, not more rpm.
The use of nitro will increase torque and thus power at a given rpm, but these engines are designed to run at a specific rpm range, so you should try to keep them there.
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Old 04-10-2012, 04:09 AM
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Default RE: Nelson q40 or 500 on 30%

It is very difficult to run a Nelson engine on high nitro contend with the nelson muffler or with a full wave pipe. With a stack pipe like in the old F1 days it is possible.

Can can advice you to stick with the 15%nitro and the engine will have a long life.

Best regards Michael

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Old 04-10-2012, 04:57 AM
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Default RE: Nelson q40 or 500 on 30%

I used to race F1 running 65% nitro in K&B, ST X-40, and finally Nelson engines, all RIRE engines. Break in was done using 15% fuel before tipping the nitro, with the engines set up for 65%. Generally would see about 800-1000 RPM difference between the fuels as well as 3 oz per minute for 65% and only 2 oz per minute with 15% which required the needle valve open a full turn more. The 65% used a plug each flight if the run was good, a piston/sleeve and new head if it went lean. If you shut down the engine quickly, you might prevent total loss of the top end, but when 4 airplanes were all together at the far end of a course you might know that someone went lean without knowing who. By the time the 3 or 4 seconds elapsed to get the plane close enough to tell which airplane, it was too late if it was your airplane.

If you can fly solo, then you can get quite a number of runs on high nitro, maybe 100. The cost of glow plugs and fuel will bring the cost to operate to about $10 each flight for a couple minutes in the air. Tank position is very important, as it is better to be too high than too low. You determine the height by what the engine does in the turns. You have to fly very smooth with high nitro, because a slight bobble can kill the plug due to a quick change in loading.

All in all, I would suggest that you experiment with nothing above 40% fuel, and would try 25 or 30% first. Unless you have a huge number of spare parts.
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Old 04-10-2012, 11:37 AM
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Default RE: Nelson q40 or 500 on 30%

Ecoli i still want to buy that 25 size speed plane from you as i have a the perfect engine for it.

I have a new Nelson F3D engine also but its going in my F3D plane. Shoot me a text and i can help you out if needed. 707-386-4284
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Old 04-10-2012, 10:34 PM
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Default RE: Nelson q40 or 500 on 30%

Getting an engine set up for speed, always work from the cold side towards the hot.
Work it in stages patiently.
I think it helps to have experience running model diesel engines.
Start out with the least amount of compression to get the engine to hit the pipe and use a prop that is on the low end of what is recommended for load.
Then carefully turn up the heat in stages with compression, load and nitro.
The first drag racers to use huge percentages of nitro successfully were a team of chemistry majors in college who went up against all the experts of the day who said that high nitro could not be run.
These guys understood that they needed low compression and a combustion chamber design that delayed detonation. They knew what to look for as far as what the engine needed for tuning.
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Old 04-11-2012, 05:14 AM
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Default RE: Nelson q40 or 500 on 30%

I thought the heading on this thread was running on "high nitro". 30% is mild sport fuel, so just adding a shim or two under the head and opening the needle valve a half turn should do it.
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Old 04-11-2012, 07:50 AM
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Default RE: Nelson q40 or 500 on 30%

Hey thanks everyone for the input. OK so 30% may not be high nitro but what I am actually trying to do is standardize my stuff. I fly all kinds of other things with 30% heli just thinking it would be easier to take one kind of fuel to the field. With the possible added benefit of a little more speed with the Q500 and Q40 planes.

ARaptor,still have the plane waiting for you in the attic, give it too you cheap if you will get her going and not let it sit around the shop like it did with me. I'll give you a call.
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Old 04-11-2012, 09:08 AM
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Default RE: Nelson q40 or 500 on 30%

Yes hit me up. i have two engines i can install in it. A Jett 35 LX FIRE or a 21 profi set up for 35,000 rpm lol just have to find the right prop for it.
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