AK Bushwheels on my Rocket, sorta..

Guys,

Just thought I would share my test results on the 380X150X5 tires on my Rocket after 100 hours. I operate off a nice but sometimes gooey 2200' home turf strip and frequent a friends 1100' rough one-way strip. The 500X5's on my Rocket were too small for the weight and footprint and I needed to try something new. I was considering going to 600X6's as my Rocket buddy Dale did until I saw Steve Sampson's post on his blog. Time to start the R&R!

First I removed the original Sam James pants, leg fairings & mount brackets. Then I removed the wheels and axles. Rockets axles are similar to the C-172, bolted to the titanium gear leg (I jack my rocket using a car floor jack with a mod to fit under one of the gear bolts)
Second I copied the aluminum van's wheelpant mounting brackets in chrome moly steel and installed nutplates. Prime/paint.
Third, installed tires and new butyl rubber tubes from Desser, cleaned/packed bearings. (note, put one thick washer underneath each brake disc bolt hole to move the disc out slightly from wheel, tires are quite a bit wider)to allow brake pad/caliper clearance from tire.
Fourth, my friend Ronnie used Steve's photos to fit my new Van's pressure recovery pants over the new tires. I stipulated one 2X4 width (4")clearance at the aft part behind the tire. Ronnie carefully made the pants contour to the tire all the way around with 1/2" clearance including dipping down around the bottom of the wheel itself, very slick, and hopefully aerodynamic. Install Team Rocket leg fairings (stronger).
Fifth Bolt it all together and go fly. Assembly showed almost 2" clearance from the top of the tire to the wheelpant (better than my RV4 with 500X5's) I used Kry-Lon to roughly paint the Van's pants and fairings for testing.

Flying: The first taxi-out really put a grin on my face as the airplane felt like a cub easily rolling along over my rough backyard. On takeoff it rolled much easier from a dead stop and of course the Rocket vertical climb...standard. My next question was speed, how much did I lose? Rather amazingly, none! It seems Ronnies attention to detail paid off as I couldn't see one knot of difference. Woo Hoo!

Epiloge: I removed the pants for final painting just before I left for South Africa last week. Ronnie expertly filled/sanded and painted the pants while I was gone, awesome! Overall I consider the 380X150X5 tire to be a vast improvement over the 500X5 on turf or gravel. Thanks again to Steve Sampson for a great idea!

Rob Ray

In my driveway

Big Uns!

Ronnie at work


Final Cut

Smokey,

My biggest concern after getting a larger footprint is whether the rocks are going to kick up off the tires into the flaps and tail. I'm not worried about grass, but gravel could be really troublesome. I used to fly my Cherokee 235 in and out of all kinds of Idaho and Utah strips, and the flaps stayed clean but the stabilator took a beating. What's been your experience?

Smoky,
Thanks for the detailed update. Question:Which gear legs, short or long, do you have? What difference do you think the length of gear will make?

(I think I see a possibility for Ronnie to make some retro-fit gear/fairings, etc.)

Presto Testo...

Guys,
The Rocket has longer gear than the RV4 with titanium legs. I am running Team Rocket leg fairings and Van's pressure recovery pants. After 100 hours now I can say the bigger tires are a home run. They're not real AK Bushwheel 36" Tundra tires, but they are an improvement. I just returned from a funeral for a friend where I operated the Rocket out of a crop duster strip I flew into alot as a kid. What a difference with the bigger tires, much smoother and higher ground clearance from the mole holes!
I have landed my RV4 and Rocket on gravel in Idaho with the 500X5's and found all the gravel hits the bottom of the wheelpant or went inside it like a fender rather than thrown into the tail. The Sam James pants on the Rocket really took a beating, they were definitely pavement only. The Rocket with 380X150X5's and Van's pants has no scratches or dings from debris, gravel or mud on the wings or tail so far. The absolute best part is taxiing on soft ground, much improved over the 500X5's. My buddy Dale went to 600X6's on his Rocket with RV10 wheelpants. He has an even better footprint than mine and lands on 1" road gravel all the time.
While I was cleaning up the wheelpants I flew the Rocket with them removed for about 5 hours. I looked underneath the wings and tail and found large streaks of mud, small scratches and several dings. More than just for speed, pants really keep the belly clean. I think you'll like the mod...

Smokey
HR2

speaking of gravel...
http://www.youtube.com/watch?v=ID-E9DFVv1o&feature=related

Thanks for sharing your knowledge and experience on this change.

I do however get the feeling there may be a little bit of "Tundra envy" present however.

Couldn't agree more...

My pleasure sir. Guilty as charged for tundra envy your honor... Despite all the fast airplanes I've been blessed to fly, you always look back to your roots...

Smokey

speaking of short field landings...
http://www.youtube.com/watch?v=6XYFcw1c-Oo&feature=related

"speaking of short field landings...
http://www.youtube.com/watch?v=6XYFc...eature=related"

Thud! Sound of jaw dropping on floor on landing )
Double Thud!! Sound of jaw dropping on floor on takeoff!
And to think of all that money I wasted learning to fly choppers.
Simply amazing.

Thanks for the link, Smokey.

Proper bushwheels!

Smokey, thanks for all the credits regarding the size of your tires. I wonder if I can get you to put proper bushwheels on your Rocket. My -4 might then be able to keep up when it is soon flying

PS Apologies for being a bit off topic.

"How to" details

smokyray said:

Guys,
........ I think you'll like the mod...

Smokey
HR2

Smokey, a few details to help me plan:

- Van's "pressure recovery pants" - these are the ones currently sold from the web store, correct? (They don't call them that.)
- Desser "butyl" tubes - are these equivalent to the Michelin air-stop types? I love my Michelins, are the butyls as good?
- When you raised your pants to clear the 2x4, were there problems with the strut/pant fairings running off the bottom of the pant? Were there problems with the support brackets being the wrong shape for the raised pant?
- What made you opt for chrome-moly brackets instead of just thicker aluminum? A thicker aluminum should be stiffer and lighter...
- Did you "fill" the nose and tail of the pants with a bulkhead to limit accumulation of debris? Do you recommend this?
- Do you run the 380-150's soft or hard, what pressure?

Thanks in advance for letting me pick your brains,
G.

Click to expand...

Do my best..

Hi Greg,
The wheel pants are the standard Van's pants off their website for all the RV models except the 10. I went with Chromemoly brackets after breaking 3 different sets of Aluminum brackets hitting fire-ant mounds on my strip. ( I spent a week on my tractor with Amdro killing them!)They weigh about the same as the .050 brackets I tried for awhile. Since the Rocket brackets require removal of the axle to attach them, I didn't want to do it twice The butyl rubber tubes were the generic copy Desser brand of tubes copying your Michelins butyl type (stay with them!). I was running the ancient aramid rubber variety requiring air every week. So far, I haven't had to add 1 lb of air since installing them last November.( I use Slime in all my tires) I ran 40 lbs to start with and then tried 50. 50 is OK, but you feel every bump and slight gear shimmy on pavement slowing down. Went back to 40 and like it alot. I didn't put any baffles in the pants as they make them heavy and the former pants (Sam James) cracked and broke where the baffles were attached inside. Ronnie did beef up the pants with triple glass where the attach screws go in. I just take the front half off at every oil change (50 hours) and check the air, tires and clean them out. I have found that if I squirt the hose up inside them with the tailwheel up on a dry wall bucket all the gook drains out nicely. You won't have any issues with fairings not matching up, the Rocket and RV4 are identical in dimension where the pant/fairing attach, lots of room. Steve Sampson's blog has great pictures of the wheelpant cutting I referenced when Ronnie started cutting the holes. http://gikonfinsh.blogspot.com/ (scroll down to Oct 24th) Ronnie worked with Roy Lopresti at Piper and made the holes look more like an hourglass then a tire shaped slot. This paid dividends in drag reduction I believe.
I think you will immediately like them both on turf and asphalt. I am babysitting my buddies 180 C/S RV4 with 500X5's and fly it often. I immediately noticed a big difference between it and the Rocket taxiing around. Good luck, let me know how it goes...

Here's a recent flying picture of the Rocket with the new "spats" and tires inflight...

Smokey

Which Tube?

Rob,

Did you use the 5x5.00 Leakguard tubes? Desser doesn't stock a Leakguard tube specifically for the 380x150.

Wouldn't surprise me if you did use 5x5's. Not much difference in size, and guys using the Goodyear blimp tires stretch 8.50 tubes to fit with no troubles.

It's time to replace my badly worn 5's and I'll be ordering replacements this coming week, so...

BTW, that was a nice tribute writeup to your friend, Brian, in this months Sport Aviation.

Thanks..

Doug,
Appreciate the kind words. Yes I used Desser's generic brand butyl rubber no leak 500X5 tubes. I infused them with Slime like all my tube tires over the years.
Just got back from ID where I put the bigger tires to test in the backcountry. Landed at U72 to fly-fish which is covered with fist sized rocks and small chuckholes. Three stock 500X5 RV's followed me in. Several had wheelpant scratches and one damaged. Mine was unscathed.

Thanks again...
Smokey
HR2

Very Cool. Upper Loon is one of my favorite fishing spots too. Did you happen to take the Rocket into Cabin Creek? That's probably my favorite place to fish up there, although it could be a toss up between Shearer and Cabin Creek.

Even with the larger tires, I'm still a little leery about taking the RV into some of these places because I'm worried about dropping that little puck tailwheel into a squirrel hole and yanking the stinger off the tail. Sure do wish there was a pneumatic tailwheel solution for the RV with maybe a little larger rolling diameter. The larger rolling diameter of the 380's would cancel out the angle of attack loss of a slightly larger and softer tailwheel.

Feel the Burn...

Doug,
My buddy Dale S. has taken his highly modified Rocket into CC many times. I didn't bother as the entire Big Creek basin looked like the surface of the moon from last years big burn. The only pretty spots were 3U2, U72 Big Creek and Smiley Crk. With daytime temps in the high 80's, trees were crucial I have taken my RV4 into Cabin Creek, Mackay Bar, Soldier Bar, Moose Creek, Upper and Lower Loon, Chamberlin and all of the long grass strips.
The Rocket at U72 was no worries, I was down and stopped by the campsite. The neat part with the Rocket is the climb rate, downright amazing! I have a API dual fork Tailwheel which I also had on my RV4 which really helps. Way better than all the others, especially on rocks.

It will be several years before the back country looks like it in in 93' on my first visit...

Smokey
HR2


Wife snapped this at BC

Yea, I'm using the API tailwheel too. I like it a lot. Just wish the 'tire' had a little bit bigger rolling diameter and possibly a hollow core for a little shock absorption.

I know what you mean about the fire damage. We were up there in June and it wasn't a pretty site. But when I'm standing in the riffles of Big Creek fly casting for trout my focus is on other things.

I think I met your buddy, Dale and his wife up there at Big Creek a couple of years ago. S****** Screamer, right? Nice folks.

Hey Smokey,

Looking to do this on my dad's RV8 soon. It already has PR wheelpants, so would it be easiest to raise/trim the pants, then rework the lower intersection fairings, or start with new wheelpants?

I've been thinking about changing mine over on both the RV and the rocket... I know when I set my wheelpants up on the RV way back in the 90's I used a 1" wood block to set the spacing from the tire to the top of the wheelpant. As best as I can figure right now it looks like I'll have 1/4" clearance if I change over to 380's. So Smokey what kind of clearance do you have? I'm not sure 1/4" is sufficient, as you get going down the runway the tires actually increase in diameter (if you want to see this phenomena, watch a drag car take off.) I've seen this problem before on other airplanes with tight-fitting wheelpants. I'd like to avoid having to move the wheelpants up to give the top of the tire enough clearance Clarence.

Only bad thing about the 380's is the price, which is double what I pay for Condor 500-5's.

smokyray said:

...Assembly showed almost 2" clearance from the top of the tire to the wheelpant (better than my RV4 with 500X5's)...

Click to expand...

(More detail in Smokey's original post)

I recall reading on Steve Sampson's site that he set his pants lower with less than an inch of clearance between the top of the tire and the pant. He seems to be having no troubles with this amount of clearance which is coincidentely the same amount of clearance that I have on my current old style Van's two piece pants.

I'm going to replace mine with the new style PR pants, but it shouldn't be any trouble redrilling to raise the pants and reinforcing and filling the old mounting holes on existing pants. This also offers an opportunity to lay a couple of reinforcing layers in the bracket attach area to strengthen it in case the wheel pant does get banged around a little. Reworking the lower intersection fairing could be problematic, though if they're bonded to the pant.

How high are your pants...

Brad/Doug/Bob,

When I went to the bigger tires and clearance under the PR pants, it was for my home strip here at the Swamp. The bigger footprint really helps when it gets gooey and soft when it rains alot, which is why I opted for the 2" clearance underneath. My friend Ronnie's requirement 2 was to be able to fit a 2X4 (4")under the rear of the pant at the tire in level (tail up) attitude. Ronnie and I did keep the pant clearance tight with the tire for drag purposes as I didn't want to lose any speed. So far in 100 hours with the mod, it is a home run across the board. The side benefit I never realized is handling on pavement, much improved.
Brad, I would put the new tires on then fit up your current pants. You can always re-drill them, trim and move them up slightly and not have to completely re-do a new set. I do recommend the steel attach brackets, much better. Bob, I have attached a close-up photo of the pants at wheel height, hopefully it answers your question. The in-flight photo below shows the bigger size is obvious, size matters Doug,my lower fairings are separate, not bonded, I like them that way. Hope all this helps...

Smokey
HR2

Tight fit

Level flight

Inside brake drain

Updated experience?

I was wondering if you have any more information now with a few more years experience?

Thank you

Still the one...

Marvin,
My Rocket went to it's new owner, a friend of mine 3 years ago and he still uses 380X150X5's on his grass/paved strip near KC. My current RVX uses the exact same setup as my HR2, down to the fairings and dimensions. After 4 years the mod is an absolute keeper, and has stood the test of many unimproved strips, roads and fields. I wouldn't change a thing, thanks again to Steve Sampson for sharing it with me.

V/R
Smokey

PS:I have discovered several soft turf/mud techniques borrowed from AK Cub drivers, here is one: Deep goo crossing: (perpetual summer wet area between my strip and hangar): Lower flaps, full aft stick and lots of power, taxi at high speed until tires get "up on step" in goo and plow/float through. Gets belly and flaps mud covered but works very well. Wouldn't have even considered it with 500X5's. Only drawback of 380's is cost, 30% more $$$...still highly recommended!

Smokey,
Thank you for the update. I am building an RV-14 and need/want the softfield ability of the mod you have on your RV. I plan to copy your tire and wheelpant setup. I have owned my current airplane 17 years with maybe 10% of my operations on asphalt. I really like grass

Marvin