Activity Stream

With all of these new upgrades, No email messages are getting through to my computer, I had every fact and every one of steve Winders comments on the Avid models and their upgrades down when I stared my Avid, I am old school an wrote them all down in a note book, You could almost build a plane up to the standard that was available at that time, I Modified mine to Mark IV specifications along with a few Pursang changes but had to lose weight in order to fly it even then. I still am having problems with trying to find an instructor for tailwheel, that is my goal, I have 3 planes almost built an ultralight an Avid and A Buttercup predecessor to the tailwind, all are taildraggers, the ultralight I have more landings than I can count but I have 30 hours with instructors in cubs and Kitfoxes and they all say I need more lessons before I get a sign off, in fact I can't get them to do a Bi annual until then. My 582 is almost back together and the Avid will be ready for inspection after I get a set of tires anyhow, I am thinking a set of those Blimp tires but that gives me about another year to get in the air legally. 

Ripped Me Off

I was the business broker that represented Mike Stratman on the sale of California Power Systems, for all my hard work I was cheated out of me earned commission.

While Mr Stratman enjoys retirement my legal bills keep escalating.

1. California Powers Systems - Caliornia Power System Breach of ...
   californiapowersystemsbreachofcontract.com

   California Powers Systems cheat their business broker, breach of contract. California Power Systems has not paid their broker fees!

If you can weld you can build a Motor mount, How would that change affect the flight characteristics of the plane. In other words would changing the thrust line have a negative to flight, I have only flown a kit fox once, and By looking down the side corner of the windshiekld I was happy with the vision, I am just uncomfortable with 2 strokes in general and I would prefer to go the other way and put my Avid engine upright, I am so close to getting this plane together that I can almost feel it, but changes that I feel lead to safety can still be made. I just have to get my hangar organized with 3 planes in it I should have another hangar, I just found out that there are only 3 planes at my airport 1 for sale 1 numbered as a DC3 and one that is supposedly owned by someone in Wyoming but at $100 a month until my wife finishes school next fall I will live with what I have. 

If you want a horizontally opposed engine that has a lot of engineering behind it, look at the BMW 1200 they were first used on Avids about 20 year ago, and have demonstrated their ability in Europe for decades as an Aircraft motor, The 3 engines that I have been looking at are the BMW 1200 oil cooled engine, the Weber 750cc , and the Yamaha Genesis engine. The BMW is one of the few bike engines that unbolts from the transmission and has shown that it is able to live in an aircraft. the Weber is seen mainly in Polaris snowmobiles in my area and usually outlives the machine that it was built in, the Yamaha snowmobile engine is the same way, the Yamaha wins in the horsepower at up to 150hp cut it down to 130nfor realistic aircraft use, the Weber is closer to 120hp and the BMW is about 100hp all three are fuel injected though had been used with carburetors in the past and while the BMW has the only true dual plug the others use an individual coil on plug, the Yamaha would be tough to squeeze a second plug in with 5 valves but the Weber might be possible. The lightest I believe is the Yamaha at 118 pounds, anywhere but the US they are considered great engines and have been worked on for years.

      Does any one Know what size tubing was used to build the Bush gear, I am not an engineer but I was an Industrial Technology Major in college and a lot of what I was taught was how to pick apart a design and modify it to work better, Tubing has different properties that can be taken advantage of depending on size and wall thickness, I have seen this gear and see one glaringly obvious but fairly easy to fix problem that will be the next point of failure.

      30 years ago I built a trailer that weighs less than 400 pounds and has hauled a 1 ton truck from LA to Des Moines with no problems by taking advantage of tubing that would do the job but not be any heavier than necessary, It is still going strong today, to bad I never get around to painting projects like that everyone wants to borrow my Backhoe trailer to haul their cars on and then complain about how heavy it was,

     In order to fix the problem I would need to Know the force that it came in at, a good guesstimate of landing speed and terrain would help and the size of the tubing, I have been working on the bush gear and can see the next point of failure that only the 1%ers like C5 are going to find, It is surprising that a 30 year old design for grass landing strips has been able to hold up to the forces imposed by the landings people are making now. Put the original gear on and if you can keep the prop out of the rocks I bet it does just as well. There is a guy on Barnstormers who has a Patent pending Air Shock design that I wish him luck with, Unless it is very heavy it won't work as well but I think the solution runs into the tubing and would like to know the thickness and the size, C5 gear failed where I originally thought they would, and If you just strengthen that you will have another failure in a similar place, By changing thee design slightly I think we could have the problem fixed but I would like to see more failures from you 1% ers so I can work on this problem.

Subaru is a better choice in a 5-7 Kitfox or an Avid that has had the fuselage mod (16" stretch) to accept the weight.

A Kitfox 4 with a (light) Subaru is a single place airplane.

The motor itself may be fine, but its not for this application. Keep looking.

Thanks for that bit of info Paul We as in those who actually have a plane flying are pushing the limits as to how far these planes were designed to ggo and how far they make it. For a design that was built 30 years ago and meant to get people flying cheap while landing on a grass strip, it is amazing how far we have taken them. I went through the other group and wrote down all of the modifications Steve Winder put down and with those I was able to upgrade my fuselage to Mark IV specifications with the B model width and then made my own copy of Merle Williams fuselage widening kit. I have been meaning to write them down here, At the same time I have been looking at the damage done to the planes and re-engineering a few things, I have an I dea on the bush gear to put the strength in that it needs, But I need to Know what size tubing the gear is made out of,and preferably how hard the landing was that caused the damage. I have priced out 18 inch travel Rok Shocks and have an idea there, but I need to know what the weight comes to, designing it as a bolt on could be a bear butsince there is no fabric around that area of the plane It should be do=able with minimal welding, Now I just have to look at Steve Winders Numbers again.

    The gear I dsigned for my own kept the same positioning back from the leading edge, but went out 14 inches wider and 8 inches taller, those he had put tubing specs down for, now its on to uncharted territory, and money, The one thing I Know is that up to the Highlander, they used the same 2 1/2 by .063 tubing for the spars and were willing to sell the inserts at a reasonable price. I used 1/4 inch plywood in mine figuring the original load test was done without anything in it. I should have kept building but at the time I was looking for a 2 place airplane and had some weight to lose, now 210 lbs lighter The Avid Became a 2 person plane even if I had not made any modifications.

Another weak point that needs a triangle is horizontal on the lower longeron and just ahead of the seat truss under the floor boards. My MK IV has a triangle formed by tubes at that point that I filled with plywood after repairing the structure there.

Yeah, that mount looks different than mine. Because my muffler actually mounts to a mount coming down off the engine mount itself. So the engine and muffler vibrate/move at the same frequency whereas with this set up because the mufflers attached the firewall and the engine vibrates around the firewall, it looks like you're asking for a leak. Bryce

Chris,

Great!  Let's chat, could you PM me your phone #?  I can possibly swing by this weekend, even if weather's not lookin up it would be worth a trip.

I have talked to ChrisB about the nosewheel - He liked the spring-loaded nosewheel attached to the steerable linkage best - If I remember right - this nosewheel is no longer made - I have one and have shared photos & dimensions of it with Steve and Amie. There are videos of it on a Challenger(?) and photos of it on Chris' plane.

I know this don't help answer about your springs.

Can you lighten the springs?

EDMO

I think the Pipers have survived the hard landings where the Avids/Foxes have gotten bent up because Piper longerons are a lot bigger and heavier than the Kitplanes - not engineer - just observing.

EDMO

How hard do you have to hit to bottom out the spring or the bungee gear? Taking the lead out of the tail and the 150lb engine off the front would be a good place to start. Like I said before, fly the airplane on to the runway! The hell with the full stall landings. Like Leni said once before, you are decending at around 1000ft per minute, If you don't judge the flare just right something is going to bend if you hit hard. I can't imagine the stress on the rest of the plane. My door latches easier on the ground than in the air. So the airframe must twist and turn while flying. It really must twist on a hard landing.

Perfect, thanks guys

The NSI is a very heavy engine. Parts and support are also not available for it. My plane had an NSI on it when we bought it and it reamained unairworrhy for many years until we saved it and yanked all that stuff the nose, removed the 40lb weight off the tail, and put a 582 back on it.

Slightly off topic, but is that a stock motor mount? Mie looks nothing like it on the engine mounts but I don't know if mine is correct or not. They used to sell just the ball and sockets for the 2 stroke exhaust it might be time for a new set, they do wear out eventually.

Mark,

I'm back in town. Could not access this site while gone. Any time you are in the area I would be happy to show you my planes, introduce you to my two other local Avid owner friends and get you a test ride/drive in one.

Chris

My opinion and $5.00 might get you a simple coffee at Starbucks, but I am a believer in the 912 all the way for the kitfox 4-7's.

The additional weight of the big direct drive 4 strokes will kill performance way beyond what you can imagine. Most of these planes whether Avid or Kitfox that have Continental or Lycoming conversions require additional weight in the tail to reach an acceptable weight and balance. I have seen first hand the difference. Flown in a 100 HP 0-200 powered KF 5 and a 80 HP rotax KF 5 and would choose the 80 HP Rotax powered hands down for short field performance and useful load. The ONLY place the 0-200 powered KF 5 outperformed the the 80 HP rotax was solo flight cruise speed.

Chris

Great topic since I have been researching gear design for the last week.

John Roberts said the front gear leg takes the greatest load and is in compression so that is why it needs to be beefier and braced like your new version is to prevent it from collapsing.

Extending and widening the gear also requires bigger diameters and wall thickness to prevent tube failure on compression.

Roberts also said the gear and cabane attach points need to be designed so the forces are applied inline with the longerons instead of twisting the longerons.

That explains why most cub style cabanes use separate attach points from the gear leg.

I was surprized to see at the High Sierra fly in that Pops Dory was not using bungees on his new Cub.

As long as the springs have enough travel to prevent metal on metal for reasonable hard hits, they sure look like the way to go.

My off road car has 2 springs per shock.

When lighter spring bottoms out the stiffer second spring takes over for progressive action.

Hi Willis!

It should be the same as model A-D, and Magnum.

Chris Bolkan

I'm back looking for opinions.  I have web-found a KitFox 4 with a Subaru E-81 NSI engine.  I have heard mixed reviews on this engine.  Anyone with experience or heard credible reviews? Mark in Sun City West, AZ

Willis,

How does the Fat Avid compare to the Magnum? I have the W&B specs for the Magnum.

EDMO

This has been somewhat of a hot topic lately so i thought I would post some various gear designs to hopefully spark some discussion from someone much smarter than me on it. The discussion is on the strength of the cabane strutted spring gear.

Airdale gear

Version two contains lighter springs a thicker wall tubing the addition of a cross brace between the front and rear leg where another set had failed.

New brace the first set didn't have

HighWingLLC gear

Super Cub Geometry on Pops Dory latest cub using springs instead of bungees

Murphy Bush Gear

Rans Brand New "Monster" Gear

Roberts Bush Gear

So it's obvious there are subtle differences between every set, but generally speaking they are all similar. So what makes one set work and another one not???

There's nothing high tech about the reinforcement.

You just cut triangles from plywood and hysol them onto the openings in the truss. Make note of where the bungees pass through and don't fill in those openings.