Airmaster Performance Upgrade

[PNWJARED]

Hey all this is Jared KF7 ULS with 26” Airstreaks. I fly with a few guys that are a bit faster than me and was wondering what top end gain I might see by adding the airmaster and whirlwind blades? I see a lot of folks posting 110 -125mph. I’m 103 at 5400rpm. Wouldn’t mind seeing a 10mph bump. Is this even in the realm?? I currently run a warp taper tip. Was going to whirlwind. Any one with data on this upgrade they be willing to share their experience?

I also fly mostly between 0-6000msl

Thanks Jared

[tjentzsch]

Hey all this is Jared KF7 ULS with 26” Airstreaks. I fly with a few guys that are a bit faster than me and was wondering what top end gain I might see by adding the airmaster and whirlwind blades? I see a lot of folks posting 110 -125mph. I’m 103 at 5400rpm. Wouldn’t mind seeing a 10mph bump. Is this even in the realm?? I currently run a warp taper tip. Was going to whirlwind. Any one with data on this upgrade they be willing to share their experience?

I also fly mostly between 0-6000msl

Thanks Jared

While I do not know anything about this, I am curious about this tpic.

[Dorsal]

Interesting numbers, I get over 120 with roughly the same set up as you. Is the 103 IAS or TAS and is it consistent with average GPS speed? Out of curiosity what is your max static RPM?

[Esser]

You have the strut fairings on? I would say before you but a $9k prop there are a few things you can do to pick up at least 5mph maybe some more.

Order jury strut fairings from Lowell. Scott Noble gained about 1.5- 2mph with that.

Then from quad city challenger, order their 5' section of 1/2" fairing material. Tell them to but it in half for shipping. It will fair your horizontal strut fairings and gain you another 2-3mph.

After I get flying I'm going to fair my gear. I have a simple design in my head that you could make out of a 4'X4' sheet of aluminum and a sheet metal brake. Using the rudder pedal mounts and the rear gear mounts to mount the sheet.

Just remember than anything that is round has the same amount of drag as a faired surface that has 10 times the diameter!

Scott Noble had almost the same set up as you. He ended up adding fuel injection but with fuel injection and an air master prop he could hit 139mph in full throttle,

[PNWJARED]

I have a Grand Rapids EIS and a steam ASI they both read the same I have crossed referenced to a gps in multiple directions, I hit 5850rpm on take off, I have strut fairings, I will look into fairing the Horizontal braces. I have not faired the jury struts. I am referring to indicated airspeed at 1500’ MSL

[Dorsal]

Well one big difference to my set up is your pitch setting. I hit 5200-5300 max static (take off) and top out at a little over 5600 WOT straight and level which produces speeds around 125 TAS.

[Av8r3400]

I have a Grand Rapids EIS and a steam ASI they both read the same I have crossed referenced to a gps in multiple directions, I hit 5850rpm on take off, I have strut fairings, I will look into fairing the Horizontal braces. I have not faired the jury struts. I am referring to indicated airspeed at 1500’ MSL

You need to put some more pitch in the prop.

[PNWJARED]

Owners manual says max rated power is 5800 which is where I am at. to meet 100% of rated HP you should achieve 5800max RPM on take off.

I have no issue getting off the ground. So I could coarsen up a bit and see how it goes

[Dorsal]

Owners manual says max rated power is 5800 which is where I am at. to meet 100% of rated HP you should achieve 5800max RPM on take off.

I have no issue getting off the ground. So I could coarsen up a bit and see how it goes

I believe a good rule of thumb (from the set up instructions?) for the Rotax 912 is for 5200ish on the ground to get good all-round performance. I also have no trouble getting off the ground though probably not a fast as you do. I would suggest pitching it for that and see what you think, will be interested in what you find.

[PNWJARED]

Update... I have added some pitch and what do ya know she’s faster! I was seeing 5800 rpm on take off/max power and would indicate around 103mph (indicated 1500msl). @5400rpm in cruise. I do have 26” air streaks so she’s not a speedster. Pitched 2 additional degrees and would see 113-115mph indicated at cruise I would see about 5400 on takeoff a little laggy on takeoff but not bad still got off pretty short just not seeing high HP. So I took another degree out and would see about 110mph @5400rpm. But I liked the rpm range and take off power a little more.

I bought a 70” whirlwind prop replacing the 68” Warp Taper Tip. Ran a couple flights today will report when I know a little more. I have roughly 21 degrees of pitch and see pretty good takeoff power cruise at about 107-110mph I think I will add a 1/2 degree. 110-112 will suit me fine.

More to come.

FYI The warp spinner and mounting plate will not work on the Whirlwind the warp is a front mount, the Whrilwind mounts behind the hub.

Thanks for all your help.

Jared,

[Dorsal]

Thanks for posting the update, very interesting. Look forward to hearing how the wirlwind works for you.