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From:=20
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On =
Behalf Of=20
Kelly Troyer
Sent: Wednesday, November 12, 2008 1:49=20
PM
To: Rotary motors in aircraft
Subject: =
[FlyRotary] IVO=20
Props, etc.
------=_NextPart_000_0021_01C944C8.A4CA0220--Doug,Did Ross state his "IVO" diameter and if 2 or 3 = blades=20 !!...............--
Kelly Troyer
"Dyke = Delta"_13B=20 ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil = Manifold=20--------------=20 Original message from DLOMHEIM@aol.com: --------------
Ross Farnham, who posts in the Van's Airforce "alternative = engine"=20 forum (and who if he wasn't a Subie guy would most likely be a = regular=20 on this list); has done quite a bit of testing with the IVO = Magnum=20 "high pitch" version on his RV-6A, turbo Subie. The best = "top=20 speed" (for what that's worth in this day and age) I could find in = his data=20 was at a DA of 17,000 ft. and " 34 inches 5000 rpm, = mixture -10%,=20 181 knots TAS". That really isn't too bad for the price = you pay=20 for an IVO in my opinion. See this link for his IVO = testing=20 information: http://www.sdsefi.com/rv13.htmHis web pages also fully document the many cooling=20 modifications he went through with his installation=20 until it finally was "right", much like those who have = gone before=20 on this list have had to do. This also is well = documented=20 and makes for interesting reading if you haven't checked out his = site=20 before. http://www.sdsefi.com/rv12.htmI plan on using an IVO on my RV-9A installation since it = appears from=20 Ross's data that it should provide more than adequate climb = performance and=20 will also cruise well in the 150-160 mph range (where I plan on = spending=20 most of my time). An MT would be nice, but the cost is=20 prohibitive on my budget. Here is a summary of Ross's IVO = conclusions from his web page:07/21/04At the 90 hour engine/prop time mark we have some more = observations on=20 the IVO Magnum:
1. We have had no issues with bolts or blades coming loose.
2. The in-flight adjustment works well. We use a 0-20 amp ammeter = to=20 judge blade position.
3. After the first set of brushes laid down carbon on the slip = rings,=20 brush life now exceeds 30 hours between changes
4. Despite having too low a reduction ratio for our = airframe,=20 the Magnum offers good takeoff and climb performance. = Medium=20 speed cruise performance is comparable to other certified aircraft=20 propellers. High speed performance also seems = comparable=20 although we'd like to have a lower reduction ratio to turn the prop = faster=20 and absorb more hp.
5. Given the speed vs. fuel flow considerations on our = turbocharged RV6A,=20 this prop is matched well and is a viable alternative to expensive = constant=20 speed, certified propellers. A fixed pitch prop on the turbocharged = engine=20 would degrade performance considerably, especially in the takeoff, = climb and=20 high altitude cruise regimes.
6. A slight vibration is set up if the propeller is coarsed out = too much=20 for the flight speed, likely due to the blade being partially = stalled.
7. Ambient temperature and altitude (density altitude) affect = pitch=20 angles required for a given hp and rpm.
For takeoff using 38 inches MAP, 4800 engine rpm/ 2182 prop rpm = we set=20 pitch at 3 amps fine of neutral pitch. This is at a hp of around = 170, prop=20 torque is 409 ft./lbs. Density altitude 3500-4500 MSL.
For climb at 35 inches MAP, 4500-4800 engine rpm/ 2045-2182 prop = rpm we=20 set pitch at 2 amps fine to neutral. This is at an IAS of 80-95 = knots. Hp is=20 150-155, torque at prop is about 374 ft./lbs. Density altitude = around 6000=20 MSL.
For cruise at 30 inches MAP, 4200 engine rpm/ 1909 prop rpm we = set pitch=20 at 13 amps coarse. This is at an IAS of 130 knots. HP is around 114, = torque=20 at prop about 314 ft./lbs. Density altitude 11,000 MSL.
We don't run the pitch past 15 amps coarse and figure that this = results=20 in a pitch of 95 to 100 inches.
(note: italics are mine...)
Doug Lomheim
RV-9A; 13B/ FWF