You're sure on 4"? Does this look like the one?

http://www.aircraftspruce.com/catalog/a ... inners.php


(I checked the one I have on my Warp Drive today and it's a 5".)

My bad, I eyeballed it as all my tape measures where elsewhere, and for some reason I had it in my head it was 4". It is indeed 5", confirmed, good call! I like it, light, simple, and cheap. Obviously I subscribe to the theory that a small spinner allows more cooling air in the cowl FWIW.

Ideally your spinner should be large enough to smooth and direct the air into your cowl inlets.

But you clearly have no cooling issues, so I wouldn't mess with it.

Got about 15-20 hours on the big bore kit now. I modified the muffler (removed the inner tube with a million holes in it, and replaced it with a 2" stainless pipe I drilled a boat load of holes in, and brought that down and out of the cowl.. welded it all back up. This gave a nice little increase to performance. Have seen a best of 1100ft climb at 8000ft altitude. Took my dad to Leadville today, and climbing out of there plenty heavy at around 600+ fpm (about 10,500 - 10,900ft altitude when I was checking). Still on a 68" warp drive which is prohibiting performance.

Added a second oil cooler because I couldn't make steady climbs without it getting too hot... now it sees 210-220 after climbing for long, long periods of time.

Looking at options, tire sizes, RANS does make a longer bush fork for a larger tire up front etc. Can get rid of the nose wheel disconnect at that point too. Then more prop.

Plane will fly much higher than I want to go....As in... It will go into airspace I'm not allowed to be in if you tell it to

Biggest surprise/added plus so far is fuel economy as courierguy was talking about. Cruising around 110mph indicated today ended up being around 3.75 gph. That was a lot of climbing too. Shoot we can knock off a little time due to warm up on the ground and still it's doing 4gph or better easy.. and that's not puttering around. 110 is my 'fast' cruise place. I mean to get that kind of economy, scooting right along for this plane, and loaded heavy... I don't know what to say.. I have been checking it for a while and seeing these results.. at first I thought I made errors but I'm seeing 3.75 to 4 an hour every flight. Sure I could burn a little more if I just beat it to death but these have become real numbers and I'm thrilled with it.

Again sorry to post all this stuff in your thread. I figure anyone else looking for zipper info can find a whole lot in one place (mostly because of your results over a large span of time). But I can add a few things based off what I'm seeing as well!

How DARE YOU post about your experiences with the Stockman BB kit on MY THREAD!

OK, just kidding there... ANYONE with comments on the mod is welcome to chime in, ain't my thread but the BB thread. The more the merrier Your comments on the fuel burn are very interesting.


I'm at a bit over 420 hrs since the mod now, and couldn't be happier. Zero issues still. Like anytime you mess around with a mod, there is a learning curve. When you do 2 or 3 mods over a short period..... the learning curve is longer. What I am pretty sure is that I now have a pretty good handle on is the BB mod, combined with the big Prince prop, and the HackMan leaner. Not to mention the (in my case) the Roberts Gear with the Rage shock system and the Micro Aero VG's. I had a takeoff yesterday that caught me by surprise. Sure the wind (15+) was straight up the mountain, but damn the takeoff roll was less then 50' (12% downgrade on my runway helped, for sure) but then the climbout was instantaneous, no in between stage of gaining speed because you horsed it off early, as soon as the wheels left the ground the climb rate was 1500 fpm + solid, and sustained (later, I thought that 50' roll could have easily been 25'). Field elevation 5400' and temps about 68 degrees. Late in the day, after 4, but heck maybe I took off into a late thermal. I am used to light planes with a fair bit of power but yesterday's takeoff was something special. Lot's of time on the S-7 wing so that helps of course, but when you keep pulling the stick back and the ROC keeps increasing and the airspeed holds and the controls stay responsive, it get's your attention! The climb angle was outrageous and I'm sure if anyone was watching they would have thought I was going to stall, not even close. I remember when I put VG's on for the first time 20 years ago on my first S-7, I THOUGHT I had a handle on what they did in the first 20 hrs., but after the next 100 hrs. I realized I was still not fully exploiting what they could do and after another 200 hrs then really got wired into them. Maybe I'm a slow learner

Hows this for BB thread drift? I got an hour in yesterday dead stick, after climbing up to 9200' at less then 4K RPM, I killed the engine and the mountain kept me up until I got bored, obviously lots of lift happening yesterday. The restart was, as usual, instant.

It took a while, but it's finally here.



I'm just about to need it. The Mangy Fox is coming together.

Hows this for BB thread drift? I got an hour in yesterday dead stick, after climbing up to 9200' at less then 4K RPM, I killed the engine and the mountain kept me up until I got bored, obviously lots of lift happening yesterday. The restart was, as usual, instant.

thats wild!!

Prince Prop + 105 Zipper = Fun

Av8r3400 wrote:

Prince Prop + 105 Zipper = Fun

Prince prop + 105 Zipper + 13 degree temps= even Funner!

Yours as light as mine? Have you noticed the sound difference? Another great thing about Lonnies prop, lighter then the Catto's I first tried, even significantly (lbs) lighter then the Kiev. The performance is gravy, the cool sound they make more gravy. This is the first winter I've had the Prince on, and a few recent cold temp flights have been impressive. I'm still on the Airstreaks though, once on the small tires and the skis, I need to make sure my prop clearance is adequate. Screw it, if it isn't as much as I'd like, I'll just hope for the best, maybe get another prop ordered with Lonnie just in case, and try and avoid taxing into deep drifts (yeah, right). My main concern is my ramp I fast taxi up to get back in the hangar, right at the start of it's transition will probably be the real test of my clearance, about as close or closer tip clearance as I'd come out flying, and at least I'll be close to home I like that prop to much to take it off for the winter, until I HAVE to. Note to Lyc./Cont pilots: a prop strike (within reason) doesn't seem to be a real big deal with the Rotax, thanks to the reduction system, still not good but not as bad, speaking from experience here

Do you know how much prop clearance you have (with the tail up)?

I put 21" mains on my nosedragger s6s, and modified the front fork for an 18" tall nose wheel. This gave me enough clearance to order a larger prop (73" scimiter 3 blade KOOL prop). Should be here soon.. expecting only 8" clearance with that prop on though

Flew today in 2-3" snow.. plane did great... little more drag rolling but overall it glided over it well! Whew it was damn cold out, but everything including trees was white.. beautiful!!

My plane hasn't flown, yet. Hoping in the next month or so...

I have 20" of ground clearance at 3-point and 14" level. (The same 78x48" prop as yours)

Here's what I'm talking about: when I transition up the ramp to the slab in front of the hangar. If it's deep enough and fluffy enough powder, I may move a little snow.... just a little fluff on top not the ground beneath or even the compacted snow further underneath. NOTE TO SELF: HIT THE RAMP IN THE THREE POINT ATTITUDE! This picture was from yesterday, still on the 'streaks. Steeper for real then it looks here BTW.

Yea thats a pretty good up ramp... can see what your talking about there

the scimitar kool prop...actually 72", not 73"



VS. a 68" warp drive



maybe get some results tomorrow, if I can find the right length grade 8 bolts...on a sunday....

had to machine the inserts down shorter to work with this hub.. been a lot of hang ups getting it on today... but anyway... should be interesting...

I don't want to be a big bore about the subject, but I just passed 500 hrs since the conversion and thought I'd check in=D> Same old same old, nothing new to report. The oil consumption, while higher then pre conversion, as expected, is around 600 ml. between the 50 hrs changes. Or at least I twice add 300 ml between changes and that maintains a good dipstick level anyway. Hal says that is by design, something about low friction rings. Whatever, it's working great, just yesterday I was working my way over a 8 K range and happened to notice I was at 4680 rpm, that's 1925 rpm for you Lyc/Cont drivers! That's increased torque in action, and it works with the big Prince prop so well......a match made in heaven, or at least part of the way up there.

On a related subject, I am going into town today, hauling my 300 gallon bulk travel tank, even though my 300 gallon permanent tank is still half full, and getting it filled with $1.92 regular (REGULAR) ethanol free mo gas before the price inches back up. Diesel is already back over 2 bucks a gallon. I will use the money saved from not buying premium to buy something useful, probably beer.

Glad to hear it! That great you just keep turning the numbers higher and higher!

My zipper has around 80-85 hours now iirc. Uses just a little oil (no hard data, just add a splash to it here and there.. maybe 5+ flights or something).

Been porting (changing shape) of a spare set of intake manifolds to tighten up EGTs. The headers I built helped, but they were still off (from front to rear cylinders). I have one side dialed in a lot closer, but the other is still got too big of a spread at cruise.. not sure why one responded better they look the same as far as the porting goes.. obviously they must not quite be the same). Fuel burn is still amazingly low considering there is more to gain from bringing air fuel ratios more inline....

What kind of take off / climb RPM do you see with your prop. What about cruise RPM? and what about flat and level wide open? Just curious what you see with that prop...

I've got about 10 hours on mine now. I did send my Prince prop back to Lonnie to get it tweaked a little. I wasn't getting the rpm that I wanted from the 78x48" original design. I was only showing 4800 on the initial takeoff roll. Performance was still amazing, but I didn't want to be lugging the engine that much. Straight and level wide open I am getting 5600 and 120 mph…

I see less then 5200 on takeoff, do most of my climbing at 52-53 and only get it to 5800 after a long build up of speed, no worries about over revving anyway for sure! I spend most of my flying time at 4950 or so, less then 5 anyway, the speed seems about the same but the fuel flow really improves, anything over 4 gpm gets my attention. I also spend a lot of time in the low 4's like 44 or even less if it's real cold, when I'm puttting around local. Yeah I know we're not supposed to lug these 912's, but I'll be damned if I'll keep it over 5 all the time as some suggest, screw that. When I hit my 2000 hr. TBO this year, I'll make a list of all the things I've NOT done correctly and let people draw their own conclusions.

IF the performance wasn't so damn good, I'd say, using conventional 912 wisdom, that we are over propped. But Lonnie seems to like to build them that way, keeping the R's down, and it's hard to argue with him when I'm so happy with the way it flies!

I agree. Most of my local playing around is 3500-4500 rpm, but I would like to see 5200-5500 at full throttle on takeoff. This is to keep from over pressurizing the crank case and blowing oil out the vent tube (what I'm getting now). This is just putting a little more stress on the case than I want, not to mention leaving horsepower unused.

I'm aiming for 5800-6000 WOT at straight and level. We know that rpm up to at least 6300 are no problem for the stock valve train with the Zipper components.

Yea it's always tough with a big prop to have all the RPMs you want. Even my 72" 3 blade scimitar is not quite "optimal" rpm wise (60mph steep climb is 5240 at my field of 6600ft) Cruise of 110mph is 5500 unless I go up high and then it takes more than 5500 to get 110 indicated. Flat and level at these elevations I fly at when farting around 7-9k will just break 6000. So I've got it about as good as I can here.. I'd love to see 5600 in a slow climb, it would be ridiculous how good it would climb I'm sure but obviously without adjustable pitch it won't happen.

When I hit my 2000 hr. TBO this year, I'll make a list of all the things I've NOT done correctly and let people draw their own conclusions.

That's awesome!!
I also understand what your saying about the RPM being lower yet the performance is still good.. when I had a 68" warp on it I could see 5400+ in a climb, but the climb performance still wasn't as good as this larger prop at a lower RPM.... and hey, if it's working, it's working I'd love to swing a huge 2 blade but I don't have the ground clearance you guys do....