Kitfox M-III Prop Comparisons for 582

[dholly 718]

I have a 582 mod 99 w/ 2.62:1 C-box, currently running a 68" GSC Tech III ground adj. prop. set to 14* degrees. Seems adequate, but the plane is headed for floats so I will need to purchase a new prop soon.

While searching around, it seems there are plenty of internet experts (surprise), but personal experience and testimonials are a bit spotty or conflicting for the 582-powered Model III specifically. So I thought it would be good if some info could eventually be pulled together here. No sense in re-inventing the wheel and my wallet thanks you.

I'd really like to hear some first hand reports from those KF-III owners with the same engine/PSRU about their fixed pitch composite props. Even better if you've experimented with multiple fixed props and can offer some insight there, ie. info on how the various diameter and pitch combinations performed on your KF-III.

Obviously, the same info for composite ground adjustable props would be great and any info on the best IFA setup for this engine/PSRU combo is also helpful, particularly on seaplanes. I'll be flying with a SP ticket but have no issue with putting an IFA switch under the cowl.

So what did you settle on? Thanks for any input!

[akflyer 1427]

I have a 582 mod 99 w/ 2.62:1 C-box, currently running a 68" GSC Tech III ground adj. prop. set to 14* degrees. Seems adequate, but the plane is headed for floats so I will need to purchase a new prop soon.

While searching around, it seems there are plenty of internet experts (surprise), but personal experience and testimonials are a bit spotty or conflicting for the 582-powered Model III specifically. So I thought it would be good if some info could eventually be pulled together here. No sense in re-inventing the wheel and my wallet thanks you.

I'd really like to hear some first hand reports from those KF-III owners with the same engine/PSRU about their fixed pitch composite props. Even better if you've experimented with multiple fixed props and can offer some insight there, ie. info on how the various diameter and pitch combinations performed on your KF-III.

Obviously, the same info for composite ground adjustable props would be great and any info on the best IFA setup for this engine/PSRU combo is also helpful, particularly on seaplanes. I'll be flying with a SP ticket but have no issue with putting an IFA switch under the cowl.

So what did you settle on? Thanks for any input!

Doug,

I went back and forth between 2.62 and 3:1 with my IVO IFA and ground adjust. I much perfer the IFA and 3:1. I know IVO says it is not recommended to use 3:1 with the ultralight prop, but in 180+ hrs I have not had an issue. I check Tq on the bolts and the SS tape between the bladed, and I have not lost any TQ on the bolts nor had the SS tape cracked. Here is what sells me on the IFA. When the prop is set for best cruise (just yesterday I had it set up at 5950-6000 burning 5.1 GPH, EGTs 1150 and 83 MPH on floats). I landed on a huge lake and decided to try a take off with the prop set for cruise. I could only get 5100 RPM initially, and after a run of about 1500' I got it on top of the water and accelerating and was eventually able to get the rpm up to 5900 or so while on the water. As soon as I broke water (around 2500 to 3000') I was able to accelerate and get the RPM up to around 6450 in a 60 MPH climb. With the 2.62 the water performance was even worse!

I tired a ground adjust hub on floats one time... To get the take off RPM I had to flatten it way out, but as soon as I got in the air I had to pull the power WAY back to keep from over revving.. Since the engine then had damn near no load on it, the EGT's went through the roof. I had to pull the power way back, get the nose up, then fly a high alpha pattern hanging it on the prop to load the engine enough to keep the EGT's under 1200. I was not liking that one little bit!

With the IFA I flatten it out to 6500 as soon as I come in with the power and if I need a small bump on TO I can feed it in. I think this is where the constant speed module would really shine, and one of these days I will buy one!

On wheels I have run the 68" GSC, Warp, Brolga and IFA & Ground adjust IVO prop. All in 68" 3 blade and my new IVO is 72" 3 blade. The only prop that was close to the IFO in terms of pull and smoothness was the Brolga, but you cant get them anymore. If I could find some I would buy all I could find as they really are an animal and it makes AKFLYERBOB'S KF perform AWESOME!

[dholly 718]

Tnx Leni - I remember you saying the 3:1 worked better with your IFA. I need to keep the switch out of the cockpit for now otherwise I'd be all over an IVO IFA. Kinda hoping to find a temporary, less expensive fixed prop solution to try with the 2.62 before I blow the big buck$. What dia and # of blades was the IVO GA you tried with the 2.62 box? Remember what you pitched at? On a scale of 1-10 in comparison with the other non-IFA and gear combos, how'd it stack up.

For fixed props w/ a 582, IVO says:

2.58 or 2.62:1 - use Ultralight 3 blade 68"

3:1 - use Medium 2 blade 68-72"

3.47:1 - use Medium 3 blade 68-72"

[C5Engineer 1170]

I'm running a 70" warp drive two blade with 2.62:1. It's the only set up I've ran but the guy I bought the set up from tried several different combos and that was the one he settled on. I turn 6300 on take off and in level flight wide open you have to work at it to get it to 6500. Over rev is not an issue for me. When I'm light I get over a 1000fpm on takeoff from Sea Level. Cruise is 5800rpm and 82mph IAS. Airplane weighs aroud 535 empty. Seems to be less gearbox chatter with the two blade over a three blade.

[dholly 718]

Joey - that's interesting, most folks say the 3-blade runs smoother than the 2-blade so I would have assumed the gearbox would follow along. I think some guys are running 72' 2-blade Warps with their 582s but it sounds based on your results like they have way too much prop. Curious, do you happen to know the factory-fixed pitch of your prop off the top of your head?

[C5Engineer 1170]

Joey - that's interesting, most folks say the 3-blade runs smoother than the 2-blade so I would have assumed the gearbox would follow along. I think some guys are running 72' 2-blade Warps with their 582s but it sounds based on your results like they have way too much prop. Curious, do you happen to know the factory-fixed pitch of your prop off the top of your head?

I think I'm around 11-12 degrees I lost track. Mine is ground adjustable.

[Av8r3400 1178]

Doug-- What if you placard the switch "Ground adjust only"...

[dholly 718]

Doug-- What if you placard the switch "Ground adjust only"...

Well, that got thru at least one Avid ramp check, eh? I dunno, I'm concerned that might be the exception rather than the rule... a little bit of [FAA] power is a dangerous thing...

[akflyer 1427]

We ran the 68" and 72" IVO 3 blade. I tried the 2 blade (72") and thought it SUCKED. Both of these I ran ground adjust and IFA. I have no idea what the pitch was on the GA as I just tweeked it on wheels to get static RPM of 6200 which gave me right around 6450 to 6500 on take off. On my buddies Mk IV with 582 and same gear box you have we took off a GSC and put on the GA 68" and it really woke the plane up. Take off, climb and cruise were much better! I have been running the 72" since I got my plane in the air and would not go any smaller for the things I do (get in and out short).

I would put the prop switch in the cockpit and put a fake one under the cowling.. you think during a ramp check they are gonna be looking for prop controls? just tell them it is ground adjust and the motor is burned out so you cant adjust it at all right now. They dont need to see it functioning during a ramp check...

[dholly 718]

We ran the 68" and 72" IVO 3 blade. I tried the 2 blade (72") and thought it SUCKED. Both of these I ran ground adjust and IFA. I have no idea what the pitch was on the GA as I just tweeked it on wheels to get static RPM of 6200 which gave me right around 6450 to 6500 on take off. On my buddies Mk IV with 582 and same gear box you have we took off a GSC and put on the GA 68" and it really woke the plane up. Take off, climb and cruise were much better! I have been running the 72" since I got my plane in the air and would not go any smaller for the things I do (get in and out short).

I would put the prop switch in the cockpit and put a fake one under the cowling.. you think during a ramp check they are gonna be looking for prop controls? just tell them it is ground adjust and the motor is burned out so you cant adjust it at all right now. They dont need to see it functioning during a ramp check...

OK, let me make sure I got this straight... on your buddies plane you replaced a fixed pitch[?] x [?" dia] GSC with a [iVO or GSC?] 68" GA 3-blade? Sounds like you may be saying the best you guys ended up with on his 2.62:1 C-box was a 68" GSC GA 3-blade... basically what I am running right now?

And, as far IFA's go- 72" IVO 3-blade might be the best suggestion to date. However, that is with a 3:1 box...

I wonder how many prop switches are labeled as trim switches? Think they would notice no elevator trim tab?

[akflyer 1427]

We (I) took off the 68" GSC 3 blade and put an IVO 68" 3 blade ground adjust on it.. It was a noticeable difference in performance and the IVO wins hands down! Take off, climb and cruise all went up, and she idled much smoother. I am going to guess due to less rotating mass on the "B" box.

[dholly 718]

B-box I thought you said C-box earlier??

Jeez you got me all confuddled now!!!

[akflyer 1427]

I have a C box, AK Bob has a C box. My other buddy had a B box. I have run the GSC on both B and C boxes and compared IVO Versus GSC on bot types of boxes, in ratios of 2.58, 2.62 and 3:1. I still like the 3:1 and IVO combo better than the GCS.

[dholly 718]

Leni - Lol, is there no friggin wonder I'm confused? All good info and saved for sure, thank you.

Now I will admit to trolling for some very specific experiences with KF-III owners who have fitted different fixed and GA props on their 2.62:1 C-box. A lot seem to be running the 68" GSC 3-blade GA like mine, but I don't know if that is more a function of being the most readily (only) available prop at the time, or because it is indeed the best prop performance w/ the 2.62:1 C-box proven over time.

In any event, with a total of (466) Model III's produced and human nature being what it is, I can't believe I'm the only one with this engine/gearbox combo who might want to tinker with different props. I also have a new GSC 2-blade GA (don't recall length off hand) that came with the plane, but since the logbook entries are less than kind and the prior owner quickly re-installed the 3-blade, I haven't given it much thought. I will, however, measure and post the size in the thread for reference of others.

[akflyer 1427]

Leni - Lol, is there no friggin wonder I'm confused? All good info and saved for sure, thank you.

Now I will admit to trolling for some very specific experiences with KF-III owners who have fitted different fixed and GA props on their 2.62:1 C-box. A lot seem to be running the 68" GSC 3-blade GA like mine, but I don't know if that is more a function of being the most readily (only) available prop at the time, or because it is indeed the best prop performance w/ the 2.62:1 C-box proven over time.

In any event, with a total of (466) Model III's produced and human nature being what it is, I can't believe I'm the only one with this engine/gearbox combo who might want to tinker with different props. I also have a new GSC 2-blade GA (don't recall length off hand) that came with the plane, but since the logbook entries are less than kind and the prior owner quickly re-installed the 3-blade, I haven't given it much thought. I will, however, measure and post the size in the thread for reference of others.

well just to quantify, I have flown the KF I, II and III with 582's in the nose.. On the III it had a warp and I did not monkey with it, but I have quite a bit on the II. There is no real difference in flying the III and the II so I tossed out what I had learned.

[dholly 718]

It's all good. Beyond the engine performance issue, did you notice a bid diff in flight/handling characteristics between the M-II and M-III? KF made a lot of the increased tail surface size and trumpeted much reduced adverse yaw etc., just curious how much was marketing hype or if you noticed much.

[akflyer 1427]

Well it was on floats, the II did not have a ventral fin, and the III did, so it was hard to tell how much was due to the fin, and how much may have been the increased vert. stab. Flying wise, I really did not notice much difference in overall handling. TO and cruise was about the same, with the edge going to the II due to the IFA and being able to get max RPM on take off. Same with the cruise.. It is just hard to beat being able to dial that pitch from the cockpit, I mean, from under the hood while on the ground wink wink

[LSaupe 123]

I know this is a rather old post but thought I would throw something out there.  I am building a KFIII, it has a grey head 582 and a GSC prop still in the box.

 

Long story short is that the engine is fitted with a 3.0 C box.  However the engine was stored with the vent plug off the gearbox and the box got water in it over the many years ruining the gear set.

 

I plan to run the GSC in the short term and change over to an IVO (68" 3 blade) in the long term.  My thought is to replace the gears with the 2.62, however, is there a penalty loss for going from a 3.0 to a 2.62 with the GSC?

 

Thanks and Regards,

 

Larry S.

[Av8r_Sed 82]

My guess is your GSC is a 66" if it came with the kit.  You'll probably be a bit underpropped.  How about contacting GSC to get their opinion?

 

http://www.ultralightprops.com/contact.htm

[IFMT 36]

Clarity on prop degrees. Just re read some of the old posts here and am wondering about prop degrees. With my warp drive I set the degrees in relation to the prop hub. The process is simple. Set the adjustable warp drive protractor to level the bubble at the prop hub. Read the degrees on the protractor. Go to the blade tip sticking out level on the port side. Set the protractor up the same way clamped   to the tip. Read the degrees and do the math. My 68 inch 3 blade warp drive works best set at 8.5 degrees at the tip. This gives me 2300 prop rpm static with my relatively stock ea81 and 1.84 reduction. Thats about as good as it it gets with this combo. I'm wondering what people are measuring when they are stating numbers like 14 degrees and prop speeds that calculate around 2500 with a 582?

[EDMO 1078]

IFMT,

     What blades are you using?  What is your engine static?

 The guy who had my Soob said he set the prop at about 11 degrees for a 4200 engine rpm static, and it would unload at 4800.  He had a 72" prop, and just guessing, the H blades? 

I think SuberAvid said about the same pitch, or one degree more,  for his prop with the higher-revving Stratus engine with 2.2:1 ratio..

     I have 70" C-blades, flat-tip, and the same 1.84:1 ratio as your redrive - hoping to get a little more pitch in the blades.

EDMO

Edited 1 May 2015 by Ed In Missouri

[IFMT 36]

Warp drive 3 blade, square  tip, nickel insert. Static off my needle tach 4200+. Unloaded to maybe 4550+. This engine is pretty much stock except for the holley 2 barrel and bigger exhaust. Distributer vacuum advance disconnected . Full static advance. When I first got the plane the prop was about 12 degrees and would easily do over 100 if I wasn't careful. Just not good take off. 2200 asl. field height. B

[EDMO 1078]

Sounds just like mine - What exhaust are you running?  Mine has straight pipes about a foot long - thinking of some 12" glasspaks for it.  Do you have the H blades, or C?  The number is on the inside end of the blades.

Ed

[IFMT 36]

This plane is in rebuild mode right now. Prop was destroyed. I think I have a pic of the serial number tag if that tells anything. 

[IFMT 36]

Took a look at the warp drive page. Pretty sure I have the HP prop with HP hub. My exhaust runs 2 into 1. Right side curves across in front of the oil pan to connect  into the left pipe which curves down and back. Connects into a short version of a swiss muffler. Muffler is custom built stainless. More or less a baffled straight pipe. I posted some stuff about this in an earlier thread. Can't remember exactly where though.