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 40 info needed

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Old 09-16-2009, 09:51 PM
  #1  
haikt
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Default Nelson 40 info needed

I just purchased this engine used and waiting to get it,
Does anyone have some info on it.
Can you please recomend prop and header+pipe I need.
It is the one with rear exhaust
thank you
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Old 09-17-2009, 08:52 AM
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Default RE: Nelson 40 info needed

Nelson makes the pipe you need for that engine. It is basically the same as teh side exhaust pipe but with a different inlet piece. If Performance Specialties doesn't have it in stock they should be able to get it for you. If not I am sure Nelson has them as I saw some when I was out there a few weeks ago, but try Performance Specialties first.
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Old 09-17-2009, 10:53 AM
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Default RE: Nelson 40 info needed

If the RE engine has high timing, it's best to run it with 7x7.5 carbon props made with continuous strand. It launches at 26,000 just on the front edge of resonance. The preferred fuel is 75/25 for breakin and 80/20 for prime time. Dave suggests lifting the glow plug element about .030". Get a stack of head shims and sneak up on the lowest setting that allows the engine to run right. .040-.050" with either the FAI or nitro head is safe. Over compression will lead to the engine getting grounded quickly. The liner needs to be set around 180-190 degrees exhaust duration for the pipe to work. Without a liner shim the timing is low enough to run open exhaust, but the engine is a weak sister unless it's on the pipe, all the ports are too big to work under the design rpm. You will need to finger choke that soup bowl to coax fuel until the engine is close to launch rpm.

If that engine has a Q-40 liner, guys are using the chopped carbon APCs in the 7.4x8 range. These might be a slight overload, just like compression you want to sneak up on the max load prop or else cook those innards.
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Old 09-17-2009, 11:41 AM
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Default RE: Nelson 40 info needed

I was watching that engine...here in the RCU Marketplace.
I asked the guy selling it a couple times if it was an FAI version or the F-1...waited almost a week, but got no answer?

When you get it, remove the head and have a look...see where the deck height is and squish band clearance...
The Formula 1 engine used a mini pipe and was designed to run on high nitro (around 60-65% ) and has lower compression, the FAI version was set up for no nitro and uses a full length pipe.
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Old 09-17-2009, 05:46 PM
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haikt
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Default RE: Nelson 40 info needed

thank you for all the info.
I will post the pictures when I get it in.
It is going to be hard to go in the plane to close the carb hole when in the plane and covered I have to come up with some remote stuff.
what should I do with it, what airframe do you think will go well with this engine.
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Old 09-17-2009, 05:53 PM
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Default RE: Nelson 40 info needed

This engine will take an extremely specialized airframe...like an FAI F3D or an old F-1 ship...maybe a mod. Q40...or something like our friend CP is making [8D]

http://www.rcuniverse.com/forum/m_88...mpage_8/tm.htm
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Old 09-17-2009, 06:31 PM
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Default RE: Nelson 40 info needed

About choking a rear intake engine that is cowled.....good question. I would guess that instead of having the typical carburetor, the throttle linkage of a rear intake racing engine works an air valve that is above a fixed fuel spray bar. This would give you both a choke and engine kill, just not much of a throttle.
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Old 09-17-2009, 06:49 PM
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Default RE: Nelson 40 info needed

The rear exhaust engine shown in the picture is probably a Formula 1 engine. This engine was set up for use with a mini pipe, high Nitro content fuel and crankcase pressure, see the nipple.


If the intent is to use it for FAI use then the port timing in the sleeve is not correct. The ports are different from the F1 version. A full tuned pipe will be needed. The crankcase pressure should be blocked off and pipe pressure used. There will be a lot of work required to convert this engine from F1 to FAI use. Propellers for either are totally different. You have to decide which version you want.

See pictures of FAI version with pipe and position of pressure fitting

Ed S
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Old 09-17-2009, 07:25 PM
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Default RE: Nelson 40 info needed

About choking a rear intake engine that is cowled
If the engine has crankcase pressure (F1) the pressure will pump the fuel around, if pipe pressure (FAI) put your finger over the end of the pipe while cranking.

Ed S
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Old 09-17-2009, 09:15 PM
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Default RE: Nelson 40 info needed

I was watching this one too. I thought the seller said it was for Q40? I'm guessing you got a tasty deal on it.
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Old 09-17-2009, 09:33 PM
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haikt
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Default RE: Nelson 40 info needed

If it is the F1 what prop should I use?
Is there a way to see which one is it other then the pressure on the case.
The seller posted it as Q40 but I think Q40s are side exhaust please correct me if I am wrong.
What is performance diff. in F1 and FAI
Thank you

Combatpig what is your name? if you fly combat I must have seen you at lone star in the past
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Old 09-17-2009, 11:20 PM
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Default RE: Nelson 40 info needed

haikt, I'm Chuck Matheny. I've flown AMA Fast since 1985, but never went further than Oregon to fly in anger. Every Summer all the pros from Texas would come out here to fly the Bladder Grabber. The only guy from around here to make the National tour is Jeff Rein.
I've run the F1 K&B 6.5 and it ran great with 30-40% nitro and a 7.2x8.6 APC. Trouble is they discontinued that prop, but something similar will work. These engines launch at 22,000 and unload impressively with an open header.
The FAI engine is designed for a 25-26,000 rpm launch with a 7x7.5. Such a tiny prop needs a low drag and light plane.
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Old 09-18-2009, 01:18 PM
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Ed Smith
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Default RE: Nelson 40 info needed

The seller posted it as Q40 but I think Q40s are side exhaust please correct me if I am wrong.
AMA 422 (Q40) Rules will not allow a rear exhaust engine.

Even with extensive rework to convert it to FAI configuration it will not be competitive with current FAI engines. Current FAI engines use props about 6.75" dia and around 8.0" pitch. The engines unload at 32,000 +.

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Old 09-18-2009, 01:34 PM
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Default RE: Nelson 40 info needed

Ed, I have have been looking (admittedly not too hard) for said 6.75x8-8.5 props. Any idea who would have these for sale ready to ship in small quantities? (for a F3D ship)
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Old 09-18-2009, 03:52 PM
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Default RE: Nelson 40 info needed

Hi!
The side exhaust Nelson .40 to the left is either a Q-500 engine or a Q-40 engine. Q-40 has higher exhaust port/timing.
Both engines run on 10-15% nitro and 17% all synthetic oil. Glow plug is a Nelson plug.

The Nelson .40 engine to the right is either a Formula one engine or a F3D pylon racing engine (FAI pylonracing). Which one could easily be distinguised by looking through the exhaust port. The F3D engine has much higher exhaust port than the F-1 engine.
The F3D engine runs on 80/0 fuel (20% Castor oil and 80% Methanol) the F-1 on 50-65% nitro and 20% synt/castor mix.

Glow plug should be a Nelson "Glow bee" plug for the 3D engine. It's important that the glow element is drawn out some millimeter to have the engine run at it's best and perform well.
Engine should be run with long tuned Nelson pipe. No tuning of the pipe is done! Just mount it and fly.

7 1/2x7" special carbon fiber props should be used for the F3D engine and rpm should be around 27000 rpm. Lower rpm than that and the engine will not function well.

Tank should be a 170cc /6oz) Tettra "Bubbleless tank" for best performance.
A good airplane for this engine is a "Big Bruce F3D pylonracer with a wing span around 180cm. Speed with this engine /plane combo is around 350-375km/h.

I have carbon props for it if you would like some.

Regards!
Jan K

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Old 09-18-2009, 05:34 PM
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haikt
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Default RE: Nelson 40 info needed

thank you for all the info.
I think it is the F1 engine but I will check and post pics when it comes in.
I do not have anything in mind for this engine yet.
I will get some props in 7-7.5" range and see what can be done.
All the info so far is about the F3D engine
what can I expect from the F1 engine? as I understand it is engine designed for more torque then RPM.
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Old 09-18-2009, 06:13 PM
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Default RE: Nelson 40 info needed

F1 engines made alot of hp from using high nitro, which negates some fo the need for super high rpms, the fai motors have no nitro so ultra high compression ratios and exhaust time with a pipe is how they are able to get the power needed, the actual gas flow on a high nitro F1 engine may exceed the actual gas flow of the FAI type engines. the fuel air ratio for nitro is 1.6-1, methanol is 4-1, so if you ran 50% nitro ,your ratio would be halfway between the two.....ask any serious nitro burner how long a 8 ounce tank lasts in the air
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Old 09-18-2009, 06:28 PM
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Default RE: Nelson 40 info needed

Judging from what I've seen so far, the Nelson should have enough builtin leeway for compression adjustment to allow lower nitro to work OK with the F-1 engine?
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Old 09-18-2009, 10:41 PM
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Default RE: Nelson 40 info needed

absolutely, and a pipe will work ok as well, the alky pipes have usually really small diameter stingers, to deal with the need for more backpressure but less volume, a mac's marine pipe will work very well with 15-50 plus nitro, the resonance is much sharper or abrupt, but still produces plenty of torque down low, the time will be somewhat lower, i would bet its still over 165 degrees....
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Old 09-18-2009, 10:50 PM
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Default RE: Nelson 40 info needed

I was noticing the differences in pipes tonight. The alky pipe has a smaller stinger, but it is fatter. The nitro pipe has a larger diameter stinger and the pipe has less diameter and smoother contours. The nitro pipe looks a lot easier to make than the alky pipe. Amazing how this stuff can be designed mathematically.
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Old 09-18-2009, 11:13 PM
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Default RE: Nelson 40 info needed

i have the link somewhere, but its a free download, java software, called design a pipe or something, you might Google it its a good fact checker for design. the nitro pipes have soo much gas volume, its kinda weird but its just physics. the tether car guys are making steel, stainless steel and titanium pipes , this is to enhance heat retention for the no nitro fuel, thus allowing the engine to come up on the pipe easier and retain more thermal energy, crazy rpms on those cars[:-]
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Old 09-19-2009, 04:12 PM
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Default RE: Nelson 40 info needed

I got the engine this morning to my surprize
I took it apart and cleand it . There is not rust in the engine but had lots of dry oil.
the only thing that i dont like is a scratch on the liner and piston.
I took some pics.
Can you tell me which version is this F1 or FAI
from what I understand this is the F1

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Old 09-19-2009, 05:24 PM
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Default RE: Nelson 40 info needed

just run it, the scratch may make very little difference, i wonder who disassembled the engine after it left the factory, the rear bearing usually has the balls exposed and the retainer facing the opposite direction, a call to performance specialties should net more info .....betting that sleeve is a lower timed unit, try to find out the exhaust duration from dave shadel
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Old 09-19-2009, 05:28 PM
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Default RE: Nelson 40 info needed

That must be the F-1 engine because the FAI exhaust port is basically even with the top of the hole in the case. If the engine holds compression after bringing the piston up to TDC for a few seconds it should still run OK, but that gouge looks pretty bad. It can happen if the glowplug element gets loose or of course from grit ingested. The edge of the wrist pin hole can slough off material on the exhaust side of the cylinder where it is hottest. The worst is having a wrist pin keeper get wedged in there.
The wrist pin has no surface treatment, it's just raw steel. Running castor will help prevent rusting. The pins clean up fine by chucking them in a drill motor and scrubbing them with rust blaster and a 3M green pad.
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Old 09-19-2009, 10:52 PM
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haikt
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Default RE: Nelson 40 info needed

Now that I got this engine what prop and pipe to get for it?
I understand that I need to get a prop in the 7.5 X7.5 range. PS offers several props for Q40 in CF, will this be good prop for the start.
I need a short pipe for the F1 engine, where would be a good place to look for one? Do i need a deather or just the pipe. what size of pipe.
I will look for a 50% nitro. this is going to be fun to find.
I will also start designing a plane to go with this engine, down the road if the scratch is bad I will get a new Liner and piston,
Thank you
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