Different speeds different models

[Bugsiegel]

I tried to search this but couldn't find a thread.
It there's one already please link it.
Vans posts estimated speeds on their site for the different models.
I have searched many different tail numbers in FlightAware and although it's not an accurate way to see how fast a plane is, it does show how fast people are flying in the system.
What model do you fly,which engine choice, what's your cruze speed and finally how fast can you go?
Paul

[Xkuzme1]

I have:
RV-4
Sensenich metal 2B prop
160 hp
Carbureted
ZFW 1028

Climb summer MATOW from 1000msl 1500-1700 fpm
-cruise 160-165 Kias
Climb winter MATOW from 1000msl 1700-2100 fpm
-cruise 165-170 kias

[plehrke]

Originally Posted by Bugsiegel

Vans posts estimated speeds on their site for the different models.

Vans published speeds on his website are not estimates. They are based on flight test data.

Originally Posted by Bugsiegel

I have searched many different tail numbers in FlightAware and although it's not an accurate way to see how fast a plane is, it does show how fast people are flying in the system.

FlightAware are ground speeds so very inaccurate to determine how fast someone is flying without knowing the wind speed/direction.

[brad walton]

Not sure why speeds would vary from summer to winter. I understand climb performance varies with temperature. But my fixed pitch speeds are constant relative to RPM.

[N941WR]

Originally Posted by plehrke

Vans published speeds on his website are not estimates. They are based on flight test data...

Very true! Plus the prop used can greatly impact cruise speed.

In my case I have an RV-9 tail dragger w/ an O-360 and fixed pitch Catto prop and typically cruise at between 55 and 65% power and see 150 to 160 knots. At 8,000 density altitude and all in (~75% power) it will true out at 174 kts but I never cruise it there.

[Toobuilder]

200 HP RV-8 Hartzel Blended Airfoil:

165 KTAS @ 8.5 to 7.5 (between 7,500 and 10,500). wot, 2300 RPM, LOP
178 KTAS @12.5 GPH (max cruise)

260 Rocket Hartzel paddle blade:

195 KTAS @ 11.5 to 10 (7.5 and 10.5). WOT, 2300 RPM, LOP
224 KTAS @ 20+ GPH (max cruise)


Both airplanes are pretty "dirty" examples. Some aero cleanup should shift the speed up a little at the same fuel burn.

[lr172]

Originally Posted by brad walton

Not sure why speeds would vary from summer to winter. I understand climb performance varies with temperature. But my fixed pitch speeds are constant relative to RPM.

They shouldn't be. The prop thrust is tied to air density. For the same reason that your prop thrust is low at 10,000 DA is the same reason that it is high at -1000 DA. The prop is pushing air. The denser the air is, the greater the ultimate thrust produced by moving that air. Cold air is denser than warm air

Larry

[pierre smith]

At 7,500' and 75% power, my -10 consistently runs 204MPH solo and 200 MPH with 4 adults. I happen to have a two-bladed Hartzell blended airfoil prop...tested as the fastest prop for a -10. Aerosport IO-540 260HP.

Best,

[brad walton]

They shouldn't be. The prop thrust is tied to air density. For the same reason that your prop thrust is low at 10,000 DA is the same reason that it is high at -1000 DA. The prop is pushing air. The denser the air is, the greater the ultimate thrust produced by moving that air. Cold air is denser than warm air

Larry

I'm just reporting facts. Same true airspeed at same RPM's regardless of altitude. Could it be that there is also less drag in thinner air proportional to reduced thrust?
To get back to OP's original question, I usually cruise at 162 ktas at 2450 rpm's and 8 gph rich of peak at 8000 density altitude. At 2700 rpm's I get 178 ktas, gph varies greatly depending on altitude
Rv8 with Superior IO 360 and and Catto 3 blade

[Bugsiegel]

What is your fuel consumption at those speeds/settings with that engine?