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Date: Sun, 28 Mar 2010 13:54:03 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: More Renesis Flight Data
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On 3/28/2010 11:34 AM, Dennis Haverlah wrote:
> Chris,
>
> Your static is very low compared to mine!  My static is in the range 
> of 5800 to 5850 rpm IIRC.  I'll confirm  static rpm soon.  Does the 
> engine run smoothly at max rpm?  I didn't know your engine was a 4 
> port Renesis - I thought it was an  earlier RX-7 unit.
>
> A question was asked about my exhaust system and Hp.
>
> I do slightly better than my neighbor's 180 hp. Lyc, powered RV-7A.  
> He and I will try to make some more comparisons this spring.  I 
> believe mine is in the area of ~190 Hp. but it is only a guess.  This 
> is one reason I wanted to post performance numbers so we can compare 
> similar and different systems.
>
> My exhaust uses the Renesis exhaust manifold.  The exhaust is pointed 
> forward toward the prop.  To reverse the flow, I used a 4" dia. 
> stainless tube mounted horizontally and parallel to the prop.  The 
> tube acts as a swirl tube - the flow enters parallel to the inboard 
> end and exits parallel to the outboard end of the swirl tube and the 
> exhaust is toward the rear of the aircraft.  The exhaust than enters a 
> Hushpower II _Resonator_ and than out and down to the rear. The 
> resonator is shorter than the normal Hushpower II muffler.  All my 
> exhaust system is inside the cowl.  I used some stainless and some 
> aluminum for heat shields.  With 230 hours of total run time I have 
> not had any problems.
> See attached picture and the article in the current issue of Van's 
> Rvaitor.
>
> When I built the exhaust system "Swirl Mufflers" were the "in thing" 
> on the list.  Also, I had trouble finding 180 deg. stainless tubing 
> with a sharp enough bend radius to fit in the space available in the 
> cowl.  If I were building it now I'd use a 180 bend stainless tube 
> instead of the swirl tube.  Probably would make a little more noise 
> and Hp!
>
> Dennis Haverlah

Hi Dennis,

I pasted the numbers from Van's web site for the 7/7A and from your 
previous post below. Van's numbers are almost certainly for a constant 
speed prop, so your climb numbers would be in the ballpark for 180-200 
hp.  But the cruise numbers don't line up at all, so I'm trying to sort 
out the reasons for the discrepancies. Full throttle, fully leaned at 
7500' with a Lyc 180 hp should produce a tad over 10 gal/hr (maybe 10.5 
on a bad day) & a tad under 200mph. Many -6's & 7's have shown this to 
be a repeatable number. If you're showing 195, you'd be in the ballpark 
for speed, but  the fuel flow is way higher than I would expect; a 5% 
penalty is understandable but a ~20% penalty is surprising. Was that 
7500' run at  full throttle and leaned to best power or full rich?

8-8.8 gph at 7500' should yield a speed slightly under the 160hp 7500' 
(75%) speed of 192 mph. Again, repeatable among multiple RV-x's.

If your neighbor's Lyc numbers are worse than yours, he's got something 
seriously wrong with either his plane or his operating technique (maybe 
afraid to lean the Lyc properly?).

Tracy & I (a rather dirty Lyc 160hp RV-4) have done a couple of 
same-altitude/same-speed cross countries together, & he's been about 5% 
worse (a reasonable, acceptable compromise #) than me both times, with 
both of us flying his low/mid altitude economy flight profiles. No one 
else flying a rotary seems to come anywhere near his fuel efficiency 
numbers. I'm curious about whether the variations from Van's numbers are 
due to major cooling drag differences, or tuning/engine setup issues.

Anyone have any thoughts?

Charlie

/Solo Weight 1400 lbs
Gross Weight 1800 lbs/ 	*160 hp* 	*180 hp* 	*200 hp*
*/Empty weight and performance measured with Hartzell 2 Blade C/S prop/*
*Speed - Solo Weight*
Top Speed 	202 mph 	210 mph 	217 mph
Cruise [75% @ 8000 ft] 	192 mph 	200 mph 	207 mph
Cruise [55% @ 8000 ft] 	173 mph 	180 mph 	187 mph
Stall Speed 	51 mph 	51 mph 	51 mph
*Speed - Gross Weight*
Top Speed 	201 mph 	209 mph 	216 mph
Cruise [75% @ 8000 ft] 	191 mph 	199 mph 	206 mph
Cruise [55% @ 8000 ft] 	172 mph 	179 mph 	186 mph
Stall Speed 	58 mph 	58 mph 	58 mph

*Climb/Ceiling - Gross Weight*
Rate of Climb 	1,400 fpm 	1,650 fpm 	1,900 fpm
Ceiling 	18,500 ft 	20,500 ft 	22,500 ft


Numbers from previous post:
Field elevation  900'
Climbed @  110 kts. indicated air speed  - Full throttle climb to 7500"
OAT 70 deg. at takeoff
Initial climb rate was 1800 - 1900 fpm
( I get ~ 2400 fpm with only 21 gallons in the tanks)

@ 4500" the climb rate was ~ 1400 fpm
Water 188 F, Oil 200 F

@ 6000' the climb rate was ~ 1250 fpm
Water 188 F, Oil 203 F , OAT 60 F

@ 7500' climb rate was ~ 1000 fpm
Water 189 F, Oil 204 F

I leveled off for about 5 minutes than went to full throttle again.

_Full throttle for about 3 ot 4 minutes @ 7500' _
MP 23.3 in.
Fuel flow - 12.1 gph
TAS 193 mph  - EM-2 data
Engine: 6660 - 6680 rpm
Water 184 F, Oil 205 F  OAT 65 F

When I fly at 7500' I _normally_ use 8 to  8.3 gph
TAS 157 mph
Water 160 F, Oil 180 F