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

Engine Dyno

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Old 11-22-2007, 08:23 PM
  #1  
ExtremeNitro
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Default Engine Dyno

I am looking for a stand that had a swinging platform that you mounted your engine to see the pulling power. I can’t find anything on it. Any suggestions?

Thanks!
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Old 11-22-2007, 08:30 PM
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Default RE: Engine Dyno

A design like that won't give linear results, what is needed is a linear effort gauge. I simply just have the engine pull straight up to see how much it can bench press.
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Old 11-22-2007, 08:35 PM
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Default RE: Engine Dyno

I am looking to compare three engines to see what one has the most power.
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Old 11-22-2007, 08:46 PM
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Default RE: Engine Dyno

Since the swinging cradle has to work against gravity the further forward it has to move.......the more your ability to see minor differences in power will be hindered. A simple [horizontal] swinging arm that presses against a digital scale should give good results and take about an hour to rig up.
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Old 11-22-2007, 08:57 PM
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Default RE: Engine Dyno

Well… I was hoping their was something on the market. Sounds like I will need to build it.

Thanks for your input!
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Old 11-22-2007, 09:09 PM
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Default RE: Engine Dyno

There is stuff on the market that I've heard of in the past.....but was ridiculously overpriced. What would you rather have, a dyno or another nice engine that you can have fun with? In view of that fact, one of those onboard "How Fast?" gizmos will give you real world results about what really matters to a speed freak for $40.
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Old 11-22-2007, 10:29 PM
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Default RE: Engine Dyno

ExtremeNitro

I don't want to sound anal, but you're talking dyno and drawing a thrust gage. A dyno measures torque, then you measure rpm to get horsepower. A 12x3 prop will out pull a 8x8 on your gage, but a 8x8 would be faster.
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Old 11-22-2007, 10:55 PM
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Default RE: Engine Dyno

Guys:

Sometimes we overlook the simple. Simple is easy for the simple minded (me). Get a decent fish scale, steal ball bearning drawer out of kitchen, use radial mount, start, read thrust in fish scale. I got caught by wife, don't do that. ENJOY
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Old 11-22-2007, 11:13 PM
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Default RE: Engine Dyno

OK… I didn’t relay want to gent into all this but I will and I hope you’re ready. First of all this is about cars/trucks not airplanes just so you know (sorry to invade your space). I have been in the market for a new engine to replace my stock M26SS engine and ended up purchasing a LRP and Dynamite mach 28. While installing theses engines I couldn’t help but notice the likeness of each. If you would like to check out the pictures go to http://www.rcuniverse.com/forum/m_6648428/tm.htm

The bottom line is I was looking for a way to compare the three engines with no fuss. The forums are filled with opinions I am looking for a hard core, bottom line way of rating the three engines!

PS: I do fly!

Thanks for your time.
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Old 11-22-2007, 11:17 PM
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Default RE: Engine Dyno

rmenke,

Now thats what I am talking about! It still sounds like I am going to make it my self and thats ok!

Thanks rmenke
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Old 11-22-2007, 11:39 PM
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Default RE: Engine Dyno

http://www.bphobbies.com/view.asp?id...=V786359&img=l
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Old 11-22-2007, 11:54 PM
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Default RE: Engine Dyno

Yaaaa…Kmot, primitive I will say, but you are on the right track!

Keep up the good work!
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Old 11-23-2007, 12:25 AM
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Default RE: Engine Dyno

These guys have all the gizmos to build a "top-of-the-line" small aircraft engine dyno. All it takes is $$$$$
http://www.land-and-sea.com/kart-dyno/kart-dyno.htm

Check out the cool all-wheel-drive RC car Dyno.
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Old 11-23-2007, 12:25 AM
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Default RE: Engine Dyno

Rich, the idea would be to use the intended prop for the task as your "control prop", like the 8x8 example. I think the thrustier applications [like 3d with a 12x3] make this type of study more relevant than what we need for speed. I don't think you will get much unloading while the engine is bolted to the kitchen table. This is why I think the best comparisons are done at the field.
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Old 11-23-2007, 12:43 AM
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Default RE: Engine Dyno

Man, a dyno is easy.

The software part is the hard part as far as I'm concerned.

All you need is a bench to test engines, a flywheel with a known mass, a calibrated-timed tach... and some software to log the whole event.
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Old 11-23-2007, 12:53 AM
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Default RE: Engine Dyno

Guys,

After fooling around with those gadgets for quite a while I found that
the Calculator of Pe Reivers is giving me the same or very near
results by just using ONLY the RPM meter. Try this:

> http://www.mvvs.nl/
>
> Click 'Propellers' on the left and then click the
> 'Propeller power calculation sheet' link. You can use
> it on-line, or download it.

and no more mess with fuels and waste of time.

Cheers,
Nick
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Old 11-23-2007, 01:28 AM
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Default RE: Engine Dyno

That's cool Nick!
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Old 11-23-2007, 01:43 AM
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Default RE: Engine Dyno

Yes, since I am electronician I have been not fully aware that those Aerodynamics
guys have such simple and robust way to calculate almost all we need to know.
And now I see what amount of time and efforts & fuel I have been wasting instead
of just typing the RPM numbers in Excel data sheet. Nowadays I am taking the
Laptop with me on the Airfield and type the numbers when I try another propeller
or fuel. I can see WHERE is the Egnine Power output versus to what I think is the
case and some times I am (and some "gurus" around too) pretty wrong in my
"great experience" predictions. It is exteremeny helpful tool. I hope you will
enjoy it too.
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Old 11-23-2007, 09:17 AM
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Default RE: Engine Dyno

ORIGINAL: combatpigg
This is why I think the best comparisons are done at the field.
Yep, the radar gun is the ultimate dyno!

I think this is what I have sitting under my desk:

http://www.clcombat.info/dyno.html

It said it works on .049 to .90s upto 240 oz-in. Anyone want to give me $60 + shipping for it, I think it went for $129.
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Old 11-23-2007, 10:31 AM
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Default RE: Engine Dyno

LOL I have not seen one of those in years. Good for comparison engine to engine for a given prop. To simulate unloading you would have drop disk area. You could work out a crude hp conversion.
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Old 11-23-2007, 11:00 AM
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Default RE: Engine Dyno

ExtremeNitro: A few years ago there was a product put on the market for "dyno-tuning" your nitro vehicles, in particular a T-Maxx and associated trucks. It was called a "D-Vise Tuning Stand" and it consisted of a chassis that had adjustable rollers on each end so that the wheels of your car/truck would fit into them. Then you would run your car/truck and the rollers would spin under a load that was created IIRC by an electric motor and somehow read or recorded. It was a pretty nice looking set-up but it was costly and the sales were probably not strong enough. So it went away.
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Old 11-23-2007, 11:03 AM
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Default RE: Engine Dyno

Check this out:
http://www.nitrodynesystems.com/

Thing is though, I don't know if he's making any more of them...I think it was lack of demand...you could ask him though. He's in the car engines forum...
Can't remember his RCU handle right off hand, but when it comes to me, I'll edit this post and put it here.
Edit: O.K. the guy who mods and dyno tests car engines is Colt4g63 (and I think he's the one who either made or sold the dynos as well? )

Those engines you have listed have already been dyno tested...rccaraction used one of his dynos to test all of the engines that they have reviewed in the mag. There's a thread in RCU's car engines forum...I just gotta remember what the title was?!
Have a look around a few pages back in there and just poke around...
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Old 11-23-2007, 04:33 PM
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Default RE: Engine Dyno

A car dyno could turn an electric motor that is hooked up to a resistive load, like a light bulb or a bank of lights. Then you would use an amp meter to register power output.
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Old 11-24-2007, 08:23 PM
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Default RE: Engine Dyno


Thanks guys but this has got a little more involved than I indented it to get. Don’t get me wrong I appreciate all of your feedback. I can see one thing you guys are really into this stuff. I have decided to go with Kmot suggestion and build a Thrust Test Stand.

Question: what would you use to measure RPM? Preferably something that I can purchase and for under $100?

Thanks!
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Old 11-24-2007, 09:04 PM
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Default RE: Engine Dyno

If you are going to use the thrust stand, you will need to attach a propeller. SO it is then very simple to measure rpm with one of the hobby tachometers on the market:

http://www.hobbypeople.net/gallery/360880.asp

http://www.horizonhobby.com/Products...?ProdID=HAN156

http://www3.towerhobbies.com/cgi-bin...&I=LXPT31&P=ML

http://www3.towerhobbies.com/cgi-bin...&I=LXPX81&P=ML
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