Did you ever get the desired material for the gear legs figured out? I was thinking that it might be an idea to talk to Robbie Grove of Grove Aircraft. He's not too far from you down in El Cajon, and he manufactures & sells leaf spring landing gear for homebuilts. Maybe he can shed some light on the subject, and/or maybe become a source for producing parts.

You busted me Eric... yes, Grove Aircraft will indeed be making the aluminum gear legs for the Fravel 172 and 182 tailwheel conversion. Robbie Grove is a good friend of mine from way back. One of the few designer/builders I trust completely and would fly in anything they build sight unseen.

What busted? It only makes good sense to go to a proven source-- why reinvent the wheel? Best of luck with it.
I believe that the original cessna gear legs are all steel-- what will the weight of these alum legs be? If lighter than 170/180 gear, that might become a W&B issue if the gear legs arm is very far from the CG.

The gear legs of my Tundra are manufactured by Grove. I am told by Dream Aircraft that to make the gear fail on drop, it would take an 8g force. Imagine 1600 lbs of impact force upward on the spine of a 200 lb man. The gear will be tougher than the gear box of the airframe or the pilot. Stuff some Charmin in your pants.

The original legs are indeed all spring steel. It is a custom alloy (6150M) that Cessna had manufactured by a steel mill. It is an otherwise standard 6150 steel alloy, but with 3 times the Vanadium content. Then it is heat treated within an inch of its life, something like 90% of the way to cutting tool hardness (255KSI).

While everyone would guess that a smaller manufactrer cannot buy enough steel to get a custom alloy made, the funny thing is Cessna probably can't do it anymore either. They reportedly have a 20 year supply of this material to support the OEM replacement parts market. This is why Cessna flat steel gear legs are eight or ten grand a pair.

Ever pick up a cessna gear leg? Considering how much people spend to save a few pounds on a lightweight starter or a lightweight alternator, using aluminum gear legs seems like a great way to save some serious weight. It's just gotta work out with the CG.

hotrod150 wrote:Ever pick up a cessna gear leg? Considering how much people spend to save a few pounds on a lightweight starter or a lightweight alternator, using aluminum gear legs seems like a great way to save some serious weight. It's just gotta work out with the CG.

Add light aluminum gear legs, then add (relatively) heavier bushwheels...no weight penalty and no CG penalty

EZFlap

I believe you did hit it on the head as there is a need for a mid size, 4 place plane that is more than your just your bread and butter 172. Placing the little wheel back where it belongs makes things fun.

X2 Zane,.... swept tails just don't look right on the ground.
Does anyone have any thoughts on the Bolins 172 TW conversions? Havn't seen one first hand but there are some out there.

EZFlap, thanks for taking on such a large but worthy project. When I get a straight tail, you can bet I'll come knocking to get the thing configured the way its supposed to be.

Kenny,
A.K.A- Bowtie

From what I have heard, there are only two active 172 conversions available now, Stoots Aviation in Alaska and Fravel with me. There is a 182 conversion in Montana which is available too.

Bolen, ACT, Bush, Texas Taildragger... it is my limited understanding that they are all dead or unsupported now. One guy's in jail, another guy won't pick up the phone, someone else got abducted in a UFO, etc. etc. Anyone PLEASE feel free to correct this, I don't want to disparage anyone else's product inadvertently.

I think Hotrod or someone else mentioned one other conversion in passing earlier, but I don't know anything about it good or bad.

These STC holders change more often than my wife changes her hair color. The Bobcat Stinson Lyc. 180 conversion has changed again. Third time in a very short while.

The Custom Aircraft Conversions/ Aircraft Conversion Technologies (aka texas taildragger) STC for the C150/152 is owned by Harry Dellicker of Porterville CA, but I understand he is not marketing it. That STC along with the CAC 320 Lycoming conversion STC & the CAC "texas ranger" 40 gallon fuel tanks STC seem to be a package deal, as Dellicker owns them also.
There is also a t/w conversion for the C150 thru C150C developed & owned by David Lowe of Sacramento, Kentucky which uses C120/140 parts.

I did not know Harry nowowns the Texas Taildragger STC. I was NOT referring to him as anyone in jail or not picking up the phone, Harry has always been responsive whenever I called for anything. He can be a cranky old bird when you get him in bad mood, but he absolutely knows his stuff and has exceptional capabilities. I believe he also has one of the STC's to put an O-360 in the 175.

Emory Bored wrote:These STC holders change more often than my wife changes her hair color. The Bobcat Stinson Lyc. 180 conversion has changed again. Third time in a very short while.

Is the Bobcat 180 stc still owned by Lands Inn outa John Day, OR still or did it already move to someone else?

fern_hopper wrote:

Emory Bored wrote:These STC holders change more often than my wife changes her hair color. The Bobcat Stinson Lyc. 180 conversion has changed again. Third time in a very short while.

Is the Bobcat 180 stc still owned by Lands Inn outa John Day, OR still or did it already move to someone else?

I don't know what to think. Somebody on the Stinson list swears up and down that it has been sold. Call Tom and find out. He takes anywhere between two weeks and never to reply to e-mail. He's a great guy to talk to and prefers phone.

Phone: 541-934-2333

An update on the Fravel SportHawk conversion, for the several people who I promised to keep informed via this thread:

I will have one of the first test-fit rough prototypes of the welded 4130 steel main landing gear fittings for show and tell at the Alaska trade show. The steel fittings are of course a little heavier than the damage-prone OEM aluminum extrusions, but they are five times stronger and will be a fraction of the cost of new Cessna parts. I will also have a CAD rendering of the new inboard and outboard fittings, so people can visualize the improvement in strength, longevity, and damage resistance. The new fittings have been designed to also allow the installation of the PPONK reinforcement (or not) as an option.

The parts kit is not yet certified, and so I will not be selling any parts at the trade show (still a few design details and finalizations in the works in the tail area). However I am confident enough that the redesigned landing gear system will pass certification to make an introductory offer up there involving the existing STC approval (which is approved and sell-able) linking it to the PMA parts kit when approved.

What I will be able and available to discuss in detail at the show is the tremendous improvements which are being made in streamlining and speeding up the conversion process. It has been finalized that (once PMA certified) the newly updated conversion will no longer require removing the wings, tail, struts, controls, rigging, etc. Thanks to hitting the "clever" button a few times, the conversion will be going from a "major surgery" project to something that can be done in a week or two.

Of particular importance will be the significant reduction of any disturbance of primary structure to do the conversion. The lower fuselage longeron hat sections and main door post structural skins will no longer be disturbed. Floorboard sections will remain attached. The control "tunnel" will not be removed or de-riveted. In short, there will be no risks related to "relaxing" or "un-jigging" the primary fuselage-to-wing structure.

The PMA parts kit will feature lightweight aluminum main gear, with options for the gun-drilled brake lines and drag-reduction profile shaping, doomsday strong 4130 main gear box fittings, increased cross sectional area bulkhead structural caps. A drilling jig and a carefully designed procedure will guarantee no gear box mis-alignment and no damage to mounting holes. There will likely be options for tailwheel units, axles, wheels and brakes.

Long story short, those pilots who have been waiting for something that fits between the Super Cub and the 180, and want a large cabin bush plane that addresses today's fuel and maintenance costs... will probably want to come by the EZ Flap booth and see what I've been up to

That sounds awesome!! Keep up the great work!!

I'm glad to see that a 172 t/w conversion kit will be available again. It sounds like you are making great progress not only in improving the t/w conversion kit, but in streamlining the installation process which will make it a much more viable option.
Keep up the good work.

What models 172's are covered?


Tom

EZFlask, ignore that drunken scrawl of yours on the back of that bar napkin regarding the name of this beast. The SportHawk moniker invokes images of an overpriced "light sport" airplane with limited resale value. It should be called SuperHawk, UltraHawk, Max Hawk, or (depending on the price) Still-In-Hock.

Thank you all for your continued interest and kind words. This thing is kicking the crap out of me, but I know I'm on to something worthwhile in this age of $6 + gas.

Models 172, 172A, 172B, and 172C are on the STC... AT PRESENT. If there is any demand I can add later 172's, but they all have swept tails and there is endless argument on the viability or desirability (and cosmetic issues) of that. To be honest, I would predict that VG's on the side of the swept tail would make the tail itself fly as good as a straight tail, but I have zero hands-on experience with that issue. The trick setup would be removing the rear window and going back to the fastback (re-creating the 1960 model config.). I'm guessing that the (expert-accused) downgrade in handling was more caused by separation behind the rear window than the sweep angle.

But I will have to get filthy stinking rich on converting the straight tail airplanes (and WW Hunter's fastback/swept airplane) first, before I went off on that kind of jihad.

"Super Hawk" was already used, for a Penn Yan 180HP conversion I believe. "Bush Hawk" was my first choice but the Canadian Found Bros. series uses that name already on one of their airplanes. I considered Mountain Hawk but I could already hear the howls of laughter from Skywagon drivers about the 145HP engine. Pro Hawk was considered, but I will assume that professional bush charter or contract operators who are making a living hauling large loads would never give up their O-470's and 520's, so invoking "professional grade" on a 145 or 180HP aircraft would insult some people.

(I actually think that there might be a paying professional niche that a converted 172 fits, but since I'm not a professional charter or bush operator it would be speculation for me to make such a claim.)

So sportsmen, hunters, fishermen, back country campers, wilderness photographers, prospectors, and families with less than 4 large people are likely the prime meat and potatoes for this "product". Anyone with abetter idea feel free to share.