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HelicopterOff Topics › I'm lookng at a model diesel engine for an​airplane...anyone familiar with these??
07-11-2008 11:36 PM  9 years agoPost 1
ERAUEAGLE

rrApprentice

Embry-Riddle @​Prescott

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I've seen some model diesel engine floating around for sale and was wondering are they like pulse jets where you just start them and they run full power all the time or can you hook a servo up just like a normal nitro one?? I know it sounds like a stupid question but I'm just curious...

Yea, I see you know everything but can see why kids love cinnamon toast crunch????

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07-11-2008 11:42 PM  9 years agoPost 2
Rob_T

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..

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There are some diesels with a throttle, but the throttle response is limited compared to a glow or spark engine (in model sizes).

Also starting on a cold day can be a test of your patience.

Finally make sure you have a fuel supply- it's been a long time since I saw a can of diesel fuel as glow is so much more popular.

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07-11-2008 11:43 PM  9 years agoPost 3
ERAUEAGLE

rrApprentice

Embry-Riddle @​Prescott

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yea, i hear ya...I've been lookng around and it seems like most people mix thier own fuel like gassers...

Yea, I see you know everything but can see why kids love cinnamon toast crunch????

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07-12-2008 12:23 AM  9 years agoPost 4
d brooks

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North Plains, OR USA

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i've only witnessed one diesel motor and i won't be getting one. my first clue was when the guy put on his coveralls and latex gloves to assemble/start his plane. He had an exhaust extension running the full length of the fuselage and the plane was still coated in black nasty, slimey, smelly gunk. Nitro/Methanol smells good... this thing smelled like FB (from Austin Powers) was cutting a perpetual "Obsideon Stout" fart. (Local beer of the stout variety). It was quiet, but that's the only thing good i could say about it.

Hey, maybe it was just this particular individuals maintenance/approach that contributed to such a foul and dirty machine. Maybe he was using some nasty home-brew fuel. Still, i'd look into it before you spend much money on it. Some folks love their diesel planes... i'll limit myself to the Cummins TD in my truck! i really don't think you'd want something like this guy had in your house or inside your car!

dMb

"The world's a big place, people just travel in small circles."

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07-12-2008 12:26 AM  9 years agoPost 5
ERAUEAGLE

rrApprentice

Embry-Riddle @​Prescott

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Nice, I just placed a bid for a 2.5 diesel on ebay for 10 bucks so we'll see what that gets me

Yea, I see you know everything but can see why kids love cinnamon toast crunch????

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07-12-2008 02:03 AM  9 years agoPost 6
Dr.Rivet

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Seattle, WA, USA

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I've had at least 10 or 12 diesel engines in my life an I loved them all. They ranged from 2.5cc Russian KNB engines which ware control line engines to Davis Diesel converted OS 46 SX. Later ran absolutely wonderful and could swing a prop 12x8 at 10K rpm. Only downside is the smell, gunk and availability of fuel. I'm not sure if Davis Diesel is still in business or not, but you can mix your own fuel based on Jet A which runs more or less clean. I've experimented with different fuel mix ratios and found that a simple formula of 3:2:1 is the best for either original diesel engine or for converted glow. Use 3 parts of Jet A, 2 parts of either and 1 part of oil (50/50 mix of synthetic and castor).

Diesel engines are not good for helis since they have lower power due to lower RPM, but like any other diesel they have almost flat torque curve across very wide RPM range which allows to hang a very large and efficient prop on them.

I would definitely recommend to anyone interested in unconventional engines to at least try one. Myself, I just love them!

The above mentioned fuel mixture is fine if temperature is above 10 deg C. If temperature gets lower you can add an ounce of amilnitrate (which is same at nitromethane to glow) and engne starts much easier at any temperature (down to Moscow winter of -25C) and idles like a swiss watch.

Tuning those beasts is an art, but lean run can't hurt them and you never risk damaging an engine from tuning it wrong. Once they are tuned right they never quit and use half the fuel (by volume) the glow does.

Make absolutely sure to change all pluming to gas plumbing or you'll melt everything instantly.

Once you get the engine PM me and I can help you over the phone to get you running.

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07-12-2008 02:15 AM  9 years agoPost 7
Dr.Rivet

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Seattle, WA, USA

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oh crap, I just searched google for​"amilnitrate for sale"

this is what wikipedia returned:
Poppers is the street term for various alkyl nitrites taken for recreational purposes through direct inhalation[1], particularly amyl nitrite, butyl nitrite and isobutyl nitrite.[2][3] Amyl nitrite has a centuries-long history of safe use in treating angina,[1] as well as an antidote to cyanide poisoning.[4][5] Amyl nitrite and several other alkyl nitrites which are used in over-the-counter products, such as air fresheners and video head cleaners, may be inhaled to enhance sexual pleasure.[6] Use is particularly prominent among urban gay men.[6] These products have long been part of the club culture from the 1970s disco scene to the 1980s and 1990s rave scene.[7]

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07-12-2008 02:37 AM  9 years agoPost 8
Dr.Rivet

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Seattle, WA, USA

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FYI

One of the harder components to get is:
Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic smell. It is the most common member of a class of chemical compounds known generically as ethers. It is an isomer of butanol. Diethyl ether has the formula CH3-CH2-O-CH2-CH3. It is used as a common solvent and has been used as a general anesthetic. Ether is sparingly soluble in water (6.9 g/100 ml).
My grandmother was a oral surgeon (now retired) and she had her own clinic and although they stopped using ether as anesthetic before I was born, she would order it in large quantities to support my hobby. Aren't grannies the best

I have no clue how to get it legally in US. Perhaps Davis Diesel guy knows...

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07-12-2008 02:41 AM  9 years agoPost 9
Dr.Rivet

rrApprentice

Seattle, WA, USA

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Most important link for anyone interested in Diesel engines in the US:

http://www.davisdieseldevelopment.com/

Now that I know that they are still in business and their web page looks even better I want to get something new!!!

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07-12-2008 03:49 AM  9 years agoPost 10
Dr.RivetrrApprentice - Seattle, WA, USA - My Posts: All  Forum  Topic

FYI

Remember with a diesel, the engine can start anytime fuel is present. It's best to familiarize yourself with diesel operation by running it mounted on a test bench. Use a slightly larger prop than you would use for glow operation. It is important to note the running differences of the engine with different compression settings, needle settings and prop sizes. WITHOUT FUEL practice flipping the prop, while adjusting the compression knob. Screwing the knob down increases compression and in turn advances the timing, backing off the knob lowers the compression and retards timing. Start with the compression knob backed off the contra piston. A significant difference can be felt with very little rotation of the knob.

Ideally, when starting the engine, the diesel will require only slightly more compression than for glow operation. Before supplying fuel to the engine, adjust to maintain this amount of compression while flipping the prop. If you back off the adjustment lever, the contra piston may remain in the higher compression position because of the drag from the O-ring seal. The contra piston will be pushed back with the slightest combustion and normal adjustment may then be made. Never force your engine over if excessive compression is felt, damage to your engine may result. Also be careful not to flood and hydraulic lock engine.

1. Set needle valve the same as for glow operation.

2. Fill fuel tank with good, fresh diesel fuel normally consisting of equal parts of ether, kerosene and oil.

3. Prime the engine with a few drops of diesel fuel in the exhaust port.

4. The compression should feel slightly higher than it was for glow operation.

5. Place finger over intake, slowly rotate engine counter clockwise over compression to fill fuel line. Then begin flipping.

6. Start increasing compression while flipping until engine fires or pops. Only slight rotation of compression lever is necessary, about 1/8 turn increments. Reprime and continue.

7. Upon starting, slowly increase compression until engine running improves.

8. Adjust needle valve until engine is running as smoothly as possible.

9. Rich setting or excessive compression will cause engine to slow down. Lean setting or inadequate compression will cause engine to run irregularly ('burping'.

10. You will have to adjust the compression and the needle valve for the smoothest setting. Always use a little more compression to take up for airborne unloading. Decreased compression settings for lower power requirements and this slower running requires richer needle valve settings. Just the opposite is true for higher power settings. When correct compression setting is achieved, lock the adjustment lever with locking arm.

11. In normal operation, your engine will start to speed up after running for a few seconds due to warm-up which serves to advance the timing. You should always rotate the compression knob back and forth to determine the proper running position.

12. Electric starting: Be careful, damage is easily done to small engines.

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07-12-2008 03:53 AM  9 years agoPost 11
Dr.Rivet

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Seattle, WA, USA

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HelicopterOff Topics › I'm lookng at a model diesel engine for an​airplane...anyone familiar with these??
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