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  #11  
Old 10-25-2017, 02:47 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 55
Default Weight and balance

Weight and balance has been a pleasant surprise. Empty weight on this plane is listed as 1091 lbs, which I understand is about the same as a heavy RV-4. I had a polished RV-4 before this, its builder was very weight conscious, to the extent that he didn't paint it, or install lights, with a Catto fixed pitch two blade prop, and it weighed 980 empty. The rocket was built light, but not to the same extreme.

With the rocket I get a gross weight increase to 1950 lbs. according to weight and balance calculations it is still aft cg sensitive, but in practice it is much less pitch sensitive than the -4. With 2up the rocket is comfortable in pitch and the trim is right in the middle if its travel where as the -4 was trimmed full forward in cruise and very pitch sensitive on landing, but that probably has more to do with the difference in props than the difference in airframes. the rocket has a BA
Hartzell.
https://imgur.com/gallery/2C5yp
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  #12  
Old 10-26-2017, 11:56 AM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 55
Default Rocket lite performance

I'm not sure this will work, but this is a speed averaging app that i used to measure speed in the Rocket. I didn't write down OAT or density altitude, but the date mid summer, so i'm sure that it was higher than standard. I also didn't record the fuel burn, but I think it was up around 13 GPH.

https://www.runtastic.com/en/users/a...28a19624b42be1

Last edited by Gt-401 : 10-26-2017 at 12:01 PM.
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  #13  
Old 10-26-2017, 12:11 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 55
Default normal cruise setting

Here is a recording of a more normal cruise power setting on the same day. I don't remember the exact fuel flow but it is normally below 9gph at these speeds slightly lean of peak.

https://www.runtastic.com/en/users/a...a7882e3e1f6fa0
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  #14  
Old 10-26-2017, 12:32 PM
Adrian Bonwitt Adrian Bonwitt is offline
 
Join Date: Jun 2013
Location: Alton, Hampshire
Posts: 12
Default

Hi Greg, you have to be a "friend" to see the numbers in the App.

Any other way to get them to us?

Thanks!
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  #15  
Old 10-26-2017, 01:00 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 55
Default try it now

I changed the privacy settings so that it should work now.
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  #16  
Old 10-26-2017, 03:40 PM
F1Boss's Avatar
F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
Posts: 618
Default results

~161kt to 178kt ground speed or so at 9GPH - close enough to call it 170kt TAS and about 155KIAS. Not too bad. Which model prop is on that ship now? I thought I heard Larry say he left the 540 prop on it...

Now we need average speeds from some of the 6cyl drivers...9GPH, and it looks like 3500MSL. What'll she do? No RPM mentioned, so just use some low-cruise MP and RPM.

Mine is an Evo, so that would not work as a point of reference. I do recall 7GPH/18"/1800 gives me an IAS of 140kt...OK in the summer when it's warm, but no can do in the winter: gets too cold.
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Mark

"Not everyone needs a Rocket. Some folks, however, shouldn't live life without one.
You know who you are."
Budd Davisson, 1997
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  #17  
Old 10-26-2017, 08:21 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 55
Default More performance notes

I was at the hanger this afternoon and I grabbed my cruise notes, these are just hand written notes during cross country flights. The true airspeed are figured by the air data computer, but I have found it to be pretty accurate compared to the averaged speeds from the app.

Press alt. 11,500. Density alt. 13,360
GPH: 7.4
66% hp
MP 20.2. RPM. 2400
OAT. 42.2 f.
IAS: 150mph. TAS: 182 mph
This power setting was about 60 degrees lean of peak

Press alt 13,500. Density alt, 14,320
GPH: 7.4
64% power
MP: 18.6 RPM:2440
OAT:21 Deg F
IAS: 152mph TAS: 191 mph
This power setting was only about 20 deg lean of peak.

Press alt 9,500 Density alt, 10,900
GPH: 8
71% power
MP: 21.9 RPM:2370
OAT:45.1 Deg F
IAS: 163mph TAS: 194 mph
This power setting was only about 20 deg lean of peak.


I'm not sure why it is calculating percent power so hi, but since all fuel flows are lean of peak, there should be a simple calculation to figure HP, but I don't know the factor for a 9.5: 1 compression ratio.
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  #18  
Old 10-26-2017, 08:27 PM
Gt-401 Gt-401 is offline
 
Join Date: Oct 2012
Location: Wray CO
Posts: 55
Default

Quote:
Originally Posted by F1Boss View Post
~161kt to 178kt ground speed or so at 9GPH - close enough to call it 170kt TAS and about 155KIAS. Not too bad. Which model prop is on that ship now? I thought I heard Larry say he left the 540 prop on it...
This Rocket has a Hartzell blended airfoil prop. I'm pretty sure it was new when he changed the engine.
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  #19  
Old 10-28-2017, 08:39 PM
Robertcropdust Robertcropdust is offline
 
Join Date: Jun 2013
Location: Tx
Posts: 32
Default Rocket/raider

I have a very nice complete HR2 0tt airframe that would make a great f4 conversion. Complete wings, empennage, fuselage, tinted canopy,cowling,wheel pants, wing tips,fiberglass fairings, new style hr2 engine mount and gear, Dynon autopilot servos installed, I have some extra parts that will go with it. This bird could be in the air fast. If anyone is interested please email me @ robertcropdust@hotmail.com
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  #20  
Old 10-28-2017, 10:00 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 3,244
Default

Quote:
Originally Posted by Gt-401 View Post
....I'm not sure why it is calculating percent power so hi, but since all fuel flows are lean of peak, there should be a simple calculation to figure HP, but I don't know the factor for a 9.5: 1 compression ratio.
I use a very simple equation for any normally-aspirated engine:

% Power = (MP / 29.92) * (RPM / Max RPM).

It seems to get close enough, for me anyway, and is independent of compression ratio and leanness. This puts your final point at 64% power instead of the 71% power mentioned.

Dave
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