Greetings all,

For a Renesis 4 port (non-priph    intake)  using Premix in fuel, what is
the
consensus of redline   RPM  for aircraft  (before PRSU) for   best
power/longevity--   .

Also, if I decide   to  switch to peripheral porting What kind of  HP
increase
and  what kind  of  fuel burn per HP, as well as longevity  decrease  can
one
expect  (all  other things being    equal).

Thanks,

Rich


The RPM red line is the  same  as  any other rotary. Limited by the prop
to about 7500  RPM. The  street RX8 is  9000 RPM

Paul  Lamar


Thanks for the  reply.

Am I to infer by your last  answer that the maxRPM is limited by  prop RPM
(to a max of 9000) and  that the  7500 limit is in reference  to the prop
tip
speed  (redced by the PRSU).

Are there any downside  effects (longevity,  severe increase in fuel used
per
HP developed,  etc) that would  prevent me from running T.O. higher than
7500. The   prop is  68"

Thanks

Rich


With a prop load and a four   port the HP will be way down from
it peak due to breathing limitations  so  you may not reach
9000 RPM in any event with a practical fixed  prop  pitch.
To reach peak power at 9000 RPM you will probably  need
a  P-port.

Assuming you are going to change the gear ratio  as even a 68"  is not
going to go 9000 RPM and you only use it for  takeoff for a max
of  5 minutes I think it might work :)

dia  =  68
RPM    Tip FPS  Vel FPS    Vel  MPH     Mach
2200      653     716      488        0.70
2250      668      729     497       0.71
2300       682      743      506         0.72
2350      697       756   516       0.74
2400       712      770       525     0.75
2450      727       784      534        0.76
2500   742       798      544   0.78
2550      757       811       553       0.79
2600   771      825      563     0.80
2650      786        839      572       0.82
2700   801      853       582   0.83
2750      816       867      591        0.84
2800   831       881      601   0.86

2800 times  2.85 is 7980 engine  RPM.

Here is a handy QB program. If you need  QB let me know
I  can send it to you. Will run under the command line in   XP.

CLS
PSRUratio = 4!
pi = 3.1416

HPrat =  .033
OPEN  "tipspee4.dat" FOR OUTPUT AS #1
PRINT #1, "RPM   HP  PROP 72   74  76  78  80  82   84  86  88   90  92  94
96  98   100"


FOR RPM = 6000 TO  8500 STEP 100
PRINT #1, USING  "####"; RPM;
HP = RPM * HPrat
PRINT #1,  USING "####";  HP;
PropRPM = RPM / PSRUratio
PRINT #1, USING "#####";   PropRPM;

FOR dia = 72 TO 100 STEP 2
DiaFt = dia / 12
tipspeed  =  (DiaFt * pi * PropRPM) / 60
IF tipspeed > 1000 THEN GOTO  skipit
PRINT  #1, USING "####"; tipspeed;
skipit:
NEXT  dia
PRINT #1,
NEXT  RPM
CLOSE
SYSTEM

Paul  Lamar

Thanks Paul.

Rich

Paul,

Thanks for the qb program, I think I can handle it, although it has been
many years since programming in C-basic using the CPM operating system.
(anybody  old enough to remember those days? Remember IMSAI)

Rich

Lot easier in native QB.

Here it is zipped.
Make a QB folder. Un zip it in the folder.
call up the command line. Get into the QB folder and type QB return.


Paul Lamar