Aero Sport Power 0-375

[supercub83a]

It is an 83” 2-blade.

So far I’m very impressed with the 375 and trailblazer. It pulls hard and does well in cruise. I run it at about 23” and 2250rpm lean of peak and average about 8gph and 90mph. Plane has 35s and slats, so lots of drag. Recently switched to 6x3 gear and that seems to have really helped heavy braking capability when light.

I do miss the simplicity of just having a single lever to control power. My prop control is on the panel, next cub build i will put it with the throttle like on the carbon cubs, so both can be adjusted simultaneously.

 

[JohnnyR]

It is an 83” 2-blade.

So far I’m very impressed with the 375 and trailblazer. It pulls hard and does well in cruise. I run it at about 23” and 2250rpm lean of peak and average about 8gph and 90mph. Plane has 35s and slats, so lots of drag. Recently switched to 6x3 gear and that seems to have really helped heavy braking capability when light.

I do miss the simplicity of just having a single lever to control power. My prop control is on the panel, next cub build i will put it with the throttle like on the carbon cubs, so both can be adjusted simultaneously.

Thanks. A few follow up questions if you don’t mind.

Are you running on the A (milder) curve or the B (hotter, bumper wire removed) curve with your Emags?

What do you think your hp is with the 9:1 pistons?

What is your static rpm (throttled up before much forward movement)

My pistons are 7.8:1, so wondering if shorter blades might be better.

Constant speed props are a way of life at work and in our Skywagon, so putting that extra knob below the dash near throttle wouldn’t pose much change for me.

 

[acroeric]

Would love to see a picture of the oil cooler install and ducting. I did something a little different on the Javron I am about to fly and always like having additional data points to compare.

 

[stewartb]

Beware that Whirlwind has an advisory NOT to use the B curve with Pmags. I presume that advice may be useful for other composite CS props. I was warned not to use B curve with my engine, too, so haven’t. I need to remove my panel switch and replace the jumper. To put it in context, at 2500 rpm the prop gets 22 acceleration/deceleration pulses per second. Lightweight props are more responsive to the pulses and higher compression increases the pulse intensity. I think that’s why WW requires counterbalanced cranks, but that’s just my supposition. The pulse thing was explained in detail by a WW engineer. What I don’t know is how/how much the pulses wear on blades, hubs, or both.

 

[tedwaltman1]

I too have an IO-375, 35" Bushwheels and slats. 8:1 compression. Whirlwind 80" CS prop.

From previous post, I can see the reported "...23” and 2250rpm lean of peak and average about 8gph and 90mph." Those numbers are in my ballpark. Though at LOP I'm seeing 6.3 ish gph and closer perhaps to 85-88 mph.

Can the Hartzell 83" prop make that much difference between our otherwise mostly identical Cubs to see 120-125 INDICATED at 3,500'? I can't imagine the prop makes THAT much difference. And at 55% power 95-100 mph? At 55% power I'm seeing 5.3 gph and 80 mph on average. I'm often at density altitudes of 6,500' to 9,500' but that altitude difference can't possibly result in those airspeed differences. BTW, my airspeed closely matches my groundspeed, so I know there isn't a "system" problem.

 

[stewartb]

Didn't 83a say that the 125mph was before slats and pod?

I don't know what others have found but while I can push my plane up to 105+ in level cruise, the plane is more comfortable to fly at 90-95, so I throttle down.

 

[supercub83a]

Im running on the A curve. As for hp, I dont have any way to tell for certain but my garmin engine monitor says I get 99% of the rated 200hp its setup for. Aerosport built the engine, their claim was 200 and 205 if I had elected to go 9.6:1. I get 2650 static rpm, but that is just a function of setting the mechanical pitch stops on a CS prop. Which is an interesting topic, from what I can gather you should set the mechanical pitch stops such that the prop wont go above redline at minimum flying speed in the event the governor fails. It registers 2700 at lift off (but thats the governor controlling).

Yes the 120 was 75% power, full rich, no slats or pod and light weight. Now, at normal weights and with slats and pod Im getting 80mph ish with 55% power. 65% lean of peak Im generally closer to 90mph which is where I normally run it. 75% and rich Im around 100-105mph. I can get the fuel flow down to about 6.5 to 7gph at the lower power settings but end up flying 75-80mph.

My numbers are just round abouts off the top of my head, I can look more closely at the data someday and post the empirical data.

 

[supercub83a]

Would love to see a picture of the oil cooler install and ducting. I did something a little different on the Javron I am about to fly and always like having additional data points to compare.

Oil temps are 180-200 generally. #3 is one of my coolest cylinders. I have the vans baffling and I made the mod Bill Rusk described of building space behind that cylinder. My oil temps can go as high as 220 on a hot day, heavy and pushing the hp. In cruise on a cool day it may be a little below 180. Before I added a cowl lip they were too high, cowl lip helped immensely with bringing down my oil temps. A controllable cowl flap wouldnt be a terrible idea. I would probably make one for a cub that is going to go much over 200hp. Another thought I had would be to use 4” instead of 3” scat to the oil cooler and have a cockpit controlled slider valve to control air through the oil cooler.

 

[tedwaltman1]

You're right Stewart...report on 120-125 mph was before slats & pod. Thank you for pointing that out.

I don't notice much change when I put my pod on in cruise speed. Similarly when I went from 6.00 x 8.50 tires to 35" tires I only saw a drop of about 3 mph in cruise. At my slow speeds, the extra drag isn't significant with pod or tire changes.

I've taken my slats off and done cruise tests at various power settings. Off the top of my head, I seem to recall only seeing a difference of about 7 mph cruise.

So, with pretty closely configured aircraft, other than the 80" vs 83" prop, where is the extra 20 to 25 mph coming from? Can't all be prop, can it?

 

[stewartb]

Seems odd. If all things were equal the shorter prop should be faster. Top speed in a Cub isn't a topic I spend much time thinking about.

 

[JohnnyR]

Would love to see a picture of the oil cooler install and ducting. I did something a little different on the Javron I am about to fly and always like having additional data points to compare.

I'm assuming you’re still referring to the Legend double cooler and cowling scoop arrangement you had asked about earlier. Sorry for delay in getting pics to you - was traveling for months.

Our oil temps run cool up here in Alaska unless I use the remote activated blocker plate (seen on left side cooler). In fact, the system is so effective with its blast tube design that I’ve taped off 30% of the right side oil cooler in spring and fall so that I can reach 180 even with the left side blocker plate fully deployed. If I was to do it over again, I'd design the scoop lower, perhaps another 1/2"-1".
Legend used to mold an even taller one that I don't believe they utilize anymore.

 

[stewartb]

Johnny, are the coolers in series or parallel?

 

[JohnnyR]

You're right Stewart...report on 120-125 mph was before slats & pod. Thank you for pointing that out.

I don't notice much change when I put my pod on in cruise speed. Similarly when I went from 6.00 x 8.50 tires to 35" tires I only saw a drop of about 3 mph in cruise. At my slow speeds, the extra drag isn't significant with pod or tire changes.

I've taken my slats off and done cruise tests at various power settings. Off the top of my head, I seem to recall only seeing a difference of about 7 mph cruise.

So, with pretty closely configured aircraft, other than the 80" vs 83" prop, where is the extra 20 to 25 mph coming from? Can't all be prop, can it?

Johnny, are the coolers in series or parallel?

Parallel - the scoop has a divider down the center and there is a hole for each hose to run down to the top of the cooler, blasting each cooler individually.

 

[stewartb]

I meant oil flow. I’m curious about how guys divide and then combine lines for two coolers in parallel. I’ve never done it and wonder how the flow balances. Mine are in series, which isn’t the most efficient way to cool oil, but it works.

 

[JohnnyR]

I meant oil flow. I’m curious about how guys divide and then combine lines for two coolers in parallel. I’ve never done it and wonder how the flow balances. Mine are in series, which isn’t the most efficient way to cool oil, but it works.

Oops!
Series.

 

[acroeric]

Thanks for the pictures fellas!

 

[supercub83a]

You're right Stewart...report on 120-125 mph was before slats & pod. Thank you for pointing that out.

I don't notice much change when I put my pod on in cruise speed. Similarly when I went from 6.00 x 8.50 tires to 35" tires I only saw a drop of about 3 mph in cruise. At my slow speeds, the extra drag isn't significant with pod or tire changes.

I've taken my slats off and done cruise tests at various power settings. Off the top of my head, I seem to recall only seeing a difference of about 7 mph cruise.

So, with pretty closely configured aircraft, other than the 80" vs 83" prop, where is the extra 20 to 25 mph coming from? Can't all be prop, can it?

I would have to go back to get the exact numbers, but I lost a lot more speed at the upper end with the slats. The 7mph is roughly what I lost at a normal 65% power setting, but I lost a lot more than that at 75% power, something closer to 15mph. At 55% it was roughly 4mph. Makes sense if they also make a lot of parasitic drag since it increases with speed exponentially. One would think their parasitic drag not that great though the numbers might suggest otherwise. I have noticed that when at a low power setting with the slats partly open, the plane does seem to drop behind the power curve rather quickly with thermals which is why I usually cruise closer to 8gph rather than 7. That makes sense to me because as they open I'm increasing induced drag. I have tested my airspeed indicator against ground speed enough to believe it at all normal cruise settings so I don't think that accounts for any differences.