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  #11  
Old 05-20-2013, 06:56 PM
Stockmanreef Stockmanreef is offline
 
Join Date: Nov 2012
Location: Midland, mi
Posts: 451
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I sort of agree with the MOGAS issue. There are very few places that sell MOGAS in my area. And unless I move closer to the airport I currently fly out of, MOGAS is not in my immediate future. My CFI was using MOGAS exclusively since i have been flying with him (about 3 yrs). He carts 5 gallon jugs to the airport all the time. Recently he stopped because he has had issues with the last two engines in his 172. He is not sure that it is MOGAS or not, but is using avgas for the time being.

It still would be a nice option to have.

Ken
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  #12  
Old 05-20-2013, 07:07 PM
TrueAirSpeed TrueAirSpeed is offline
 
Join Date: Jan 2006
Location: 36U
Posts: 208
Default My I0-390 burns 9.0 GPS at cruise

Went to OSH last year about an hour behind an RV-6 with a fixed pitch Catto prop. He landed 15 minutes ahead of me at Ainsworth, NE. and we both took the same amount of fuel. I have dual PMags and auto plugs.
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Terry Small
RV-7 "Sasha" (1000th completed), IO-390, SJ cowl, ww prop
Deferred by combat (OEF '04 - '05, AH-64A)
Building a Bearhawk

When you're at the end of your rope tie a knot in it, and hang on . . . .Joe Back
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  #13  
Old 05-22-2013, 12:12 PM
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=c= =c= is offline
 
Join Date: Apr 2012
Location: Tallahassee, Fl
Posts: 12
Default 9.0 gps

32,400 gph? That's quite amazing.

A new record I think.
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  #14  
Old 05-23-2013, 11:51 PM
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n82rb n82rb is offline
 
Join Date: Jan 2007
Location: fort myers fl
Posts: 633
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for a RV it might be a record, but ask paul dye what his work plane burned an hour.

bob burns
RV-4
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  #15  
Old 05-24-2013, 01:50 PM
parkke parkke is offline
 
Join Date: Nov 2011
Location: Dayton,Ohio
Posts: 3
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Quote:
Originally Posted by rvbuilder2002 View Post
"good choice" is rather subjective.

Any engine near the HP of the recommended IO-390 can work fine to fly the airplane, but if it is not of similar weight it can add many complications (far more than just ballasting the airplane to get the C.G. correct).
Well, the IO-390 is 308lbs dry, the IOX-370 is 255lbs + accessories. I'm expecting very similar dry weights. What other complications were you thinking of? CG location may be corrected through proper ballasting. Iyy can be corrected in a similar manner.

I'm genuinely curious what you think.
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  #16  
Old 05-24-2013, 07:58 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 6,972
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Quote:
Originally Posted by parkke View Post
Well, the IO-390 is 308lbs dry, the IOX-370 is 255lbs + accessories. I'm expecting very similar dry weights. What other complications were you thinking of? CG location may be corrected through proper ballasting. Iyy can be corrected in a similar manner.

I'm genuinely curious what you think.
I think that adding accessories to an IOX-370 wont add 53 pounds.

I was talking in general terms of using different engines.
If for an example we talk about using a bigger /heavier engine.

Say it requires a longer cowl than the original design. This adds side profile area to the airplane fwd of the C.G. Aerodynamically, this is the same as reducing the size of the vertical stabilizer/rudder. It can have an effect on yaw stability and spin recovery.

Lets say the bigger/heavier engine also requires adding ballast to correct the C.G. position. The logical place to add balance weight is as far aft as possible because then the smallest amount can be used. This corrects the C.G. problem but it increases the polar moment of inertia.
In simple terms, adding any amount of weight, a large distance aft from the C.G. make the airplane more resistant to changes in yaw and pitch (changes that we want to be able to induce with the controls), and more difficult to stop pitch and yaw motions once they are in motion (something that we don't want). This can have an impact on pitch and yaw stability, and particularly, spin recovery.

So, I am not saying that using any engine other than what was recommended, means you will have serious problems related to what is described above...
I am saying that you might (and not even know it, because how many people flight test to that high of a level of detail... or know how).

Bottom line -

It requires a lot more than a set of scales, to establish that an airplane will fly exactly the same as was intended by the designer, when a different engine is used.
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RV-6A (aka "Junkyard Special ")
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  #17  
Old 06-18-2013, 01:33 PM
parkke parkke is offline
 
Join Date: Nov 2011
Location: Dayton,Ohio
Posts: 3
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Quote:
Originally Posted by rvbuilder2002 View Post
I think that adding accessories to an IOX-370 won't add 53 pounds.

Bottom line -

It requires a lot more than a set of scales, to establish that an airplane will fly exactly the same as was intended by the designer, when a different engine is used.
You haven't seen my accessories. You make some good points. As far as the polar moment is concerned (Iyy in my previous post) I wouldn't have to ballast aft of the cg, and whatever ballast would be required up front to account for the engine weight delta would most likely bring the moments back to where they should be.

The ECI engine is about 2 inches longer, and I'd be curious if the stock cowl would fit. As far as destabilizing aero effects, 2 inches on the fuselage planform isn't much when compared to the total acreage of the fuselage.

Your answer was quite good, thanks. Just so you know, when I'm not dreaming of building airplanes, I actually work as an Aerospace Engineer designing hypersonic airframes so I'm familiar with the design principles. That said, I appreciate the expertise of experienced builders. They always have good input.
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  #18  
Old 11-19-2013, 10:13 PM
Bernard Hartnell Bernard Hartnell is offline
 
Join Date: Jul 2013
Location: Grand Junction, CO
Posts: 49
Thumbs up IO360 235 hp

I am coming along with my IO 360 ang. Valve. Have the Cyl. Port & polish and tri valve grind in process. Cyl. 10 over with10.1 treated pistons. Case line bored and ready, new exp. bal. crank. Duel PlasmaIII with Mini sensor Light Speed ignition. (About the same cost as two standard mags, although LS comes with auto spark plugs and thread adapter and all lines (wires) all included.
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  #19  
Old 12-23-2013, 06:05 PM
AeroBuilders AeroBuilders is offline
 
Join Date: Sep 2011
Location: Austin, TX
Posts: 25
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UL Power 520is --- > 200hp running on MOGAS and just over 250 pounds for engine weight. I will take MOGAS option over 100LL any day of the week and even on a Sunday!

The UL Power 520is has a nice torque curve with great 6 cylinder power. An RV-14 with UL Power would be a great match.
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  #20  
Old 12-24-2013, 08:30 AM
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M McGraw M McGraw is offline
 
Join Date: Dec 2012
Location: Greenback, TN
Posts: 322
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Quote:
Originally Posted by AeroBuilders View Post
UL Power 520is --- > 200hp running on MOGAS and just over 250 pounds for engine weight. I will take MOGAS option over 100LL any day of the week and even on a Sunday!

The UL Power 520is has a nice torque curve with great 6 cylinder power. An RV-14 with UL Power would be a great match.
I looked up this engine on the website. It requires 98RON octane fuel and 3200rpm to get the 200Hp.

I have never seen 98RON octane MOGAS. Do you have that in Texas? The best MOGAS I can get in Tennessee is 93(R+M)/2. What is that equivalent to in RON? Also, the IO390 gets the Hp at 500 RPM lower than the UL 520is; what Prop does it use? What is the Hp at 2700rpm since it is a direct drive engine?

UPDATE: I DID A GOOGLE SEARCH ON RON VS (R+M)/2. IT APPEARS 98RON IS VERY SIMILAR TO 93(R+M)/2. (R+M)/2 IS TYPICALLY 5 OCTANE POINTS LOWER THAN RON.

Thank you
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RV-14. #140039 Complete
Flight hours: 85+

Last edited by M McGraw : 12-27-2013 at 07:40 AM. Reason: Update
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