V8 engine Cessna 172

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Victor Bravo

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I agree with Charlie, in that you can use the homebuilt community to very easily generate a lot of fleet data that is relevant to your certification effort.

If you have ten Bearhawks or Comp-Airs or Lancair 4P's flying around on your engine, you will have data that is very attractive to the FAA.

Although not homebuilt related:

If you do what they did in Australia, putting an LS engine on the front of a Pawnee (at a busy glider club) you can get thousands of hours of actual high power level engine data at no cost. In your case, if you found a few glider operations using Pawnees or CallAirs, you could offer them a better deal on a replacement engine, and they get greatly reduced operating cost in return for your data loggers being in the airplane. They still buy the engine, or you give it to them at cost, so your cost for that data is mitigated.

If you go to the banner towing companies that still use Stinsons or 182's for larger banners, you have an opportunity to get a whole lot of flight time over a three month Summer beach season.

You could find half dozen ag spray outfits that are using the Pawnee or AgWagon, and gave them a discounted engine package in return for a whole bucket full of recorded flight data.

So when it comes time to formally apply for the STC, you'll have a larger amount of supporting data for reliability, safety, etc. Forgive me if you had already thought of all this, it is all common sense of course, but please take this suggestion as supportive in nature and not chastising or obstacle-throwing.
 
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Brünner

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Thanks for the encouraging comments, its motivating & much appreciated.

As for those more critical RE experimental limitations: Your understanding of experimental limitations is wrong and outdated. Experimental op limits were re-written years ago that remove most of the restrictive op limitations for the exhibitions category, and became nationwide policy rather than subjective to individual FSDO's (although local FSDO can place additional limits for extraordinary locations or circumstances). These limitation are clearly listed in FAA policy 8013 and for a class 1 aircraft as a single engine piston, they are near identical to amateur built op limitations. The Corsair C172 holds a multi purpose AC, including exhibition category, which places no geo limits on post phase 1 maintenance of proficiency flying, for example. Additionally, FAA policy (ref FAA order 8130.2j) allows flight training in experimentals as long as no compensation is received for aircraft. Moreover, an experimental flight club is indeed permitted as long as structure is members own part of the aircraft and reasonable fees are paid. With FAA changing LSA rules to allow up to 6 seaters, this makes the certification argument moot. Regardless, putting a certified in EXP is not as limiting as yesteryear.

Again, a lot has changed in the last 10 years RE EXP op limits, kudos to EAA and warbird associations advocating. Our program took considerable time being accepted by FAA and we had to provide many technical documents and procedures; which we abide by.
...........
The changes RE experimental limitations are truly impressive. As a European pilot I admit to be green with envy, but I also admire the enormous amount of dedication and work your various associations did to make this happen.
Kudos to you guys!
 

rv7charlie

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One of the earliest automotive V8 a/c applications I read about was the skydiving operation in Australia (or NZ; we barbarians tend to lump them together. Sorry..) IIRC, they started with a Ford V8 V6 & eventually switched to GM. No shock cooling, better fuel economy, etc etc. Wish I could supply a link, but I keep finding and then losing it.
 
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Victor Bravo

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The story I had heard about Australia was that a busy glider club did an LS conversion as a closely monitored experiment with gov't approval. They saved enough money on direct operation and maintenance costs of the towplane that they could afford a brand new AS-K21 training glider with the savings. The fuel savings were significant enough by themselves, and then the shock cooling and everything else mechanical created additional savings through decreased maintenance.
 

Voidhawk9

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...in Australia (or NZ; we barbarians tend to lump them together. Sorry..)
That's like confusing the Lord of the Rings with Crocodile Dundee! 😜

There was a Cresco that was tested with a V8 some years ago:
Not sure where it faded away to, I've never seen or heard one so configured besides this video.
 

pfarber

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There are two other experimental certificates he could qualify for, R&D and Market Research. Both would be 100% legit in this situation.

Going from the mid 1930's to the early 1990's is a pretty big jump in efficiency as far as I can see.

He could have tried to get all the way into the 2000's, and use the engine off of the Raptor, but we see how that's working out.

He could get all the way into the 2020's and try to use batteries, which would work just fine except for being the world's first single-seat limited Cessna 172.
I mentioned the 'other' R&D categories in my post, but I don't think the FAA would allow, en mass, 172s to be re-certified as such. There is a SeaBee with a V8 that's under the R&D thing and its limited also.


This started in 2000.. so again.. and LS in a certified AC, YAWN. To date (21 years later) there are only 9 flying SeaBee's. They didn't even go to the trouble of a new ECU... just tweaked off the shelf parts.

If they are trying to STC this... good luck. If it was cheap or viable someone, somewhere would have done it already.

Gee, let me quote some very authoritative sources on why I think this is a neat side project, but will not go anywhere:


So yeah... its dejavu all over again.

Also this Quiet Aviation


Started in 2008.

The FAA comes down hard on pilots for 'holding out' even to friends/family... do you think they they will turn a blind eye to experimental AC flouting the 'market research, demonstration, crew training' requirement of the FAR?

Bottom line: unless they have the backing to PMA a complete engine, PSRU and electronics and STC it and NOT use this experimental category as a work around this is a side project that's been done many, many times.
 
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wanttobuild

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The perfect engine for the Bearhawk. Use the engine block as a stressed member, and mount directly to longerons with insulated mounts. One sweet arse machine. Want a real all-round machine?, use the Patrol airframe. Go ahead and add 6way powered seats. Bmw makes some very nice oem leather, that really look light enough. Power the refrigerant compressor with a Lovejoy.
Instead of fabric, a nice tight fiberglass exterior, (for making the ship airtight), nice silicon bulbs for the door gaskets, I've been watching tooooo much Scrappy
 
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speedracer

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Did not go back & check density altitude if posted for vid, but my old C175 climbed considerably better than that with one on board into a strong head- or quartering crosswind at FDK. It also burned just over 11 GP"H" at almost any throttle setting in the green, per _tach_ hour. Wonderful, electric-motor smooth engines. (As with all aero engines) should have been subject of a bit more development.

Love the auto V8 concept & efficiency, though, how much does it weigh, FWF with all fluids?

smt
What does a headwind (or tailwind) have to do with climb rate?
 

Aviacs

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What does a headwind (or tailwind) have to do with climb rate?
Good point.
Was remembering the elation of elevator like steady 1,200+ fpm rise on a couple of cool, strong windy days -
& confusing the sensation of better climb angle/Vx.
The airplane, 3/4+ tanks, me alone, would climb1,000 fpm any reasonably cool day at approximately sea level.
800+ with 2 on board.

The rest was so long ago, will defer to the book.
Thanks for the nudge.

1960 Cessna 175 & Skylark
Book data: ____GW-------------FPM, SL 59F------------5,000 ft 41F-------------10000ft 22F-------------15000 5F
..........................1,700.....................................1,395.........................1090...........................................790.........................................475
...........................2,000....................................1,105...........................840............................................575.........................................310
...........................2,350......................................850............................615.............................................380.........................................140

The airplane surprised most of the experienced people who flew it.
Weak point of the GO-300 was not really the gearbox or lower end which if flown by the book were near bullet proof to TBO. Cylinders were "improved" & slightly different from the O-300's which actually have similar cylinder problems. Always wondered what Superior or Millenium Cylinders would have done for the engine. TBO was 1,200 hrs but not so different from others of the era & could have been improved with cylinder development.

Connection any of above re: OP is comparison of "similar" factory airplane (C172 airframe) with visible performance in the video. The possible additional improvement in climb regime with a geared engine and longer than "normal" prop at same HP. Straight prop C175's have 84" prop. Wonder what the OP is using? And, the issue others have noted, how much HP is actually being produced at 11- 11.5GPH Which was C175 typical fuel flow per tach "hour".

smt
 
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Pops

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When the article about Bob Barrows Bearhawk came out in Oct issue of SA I was designing a steel tube, 44" wide, 4 seat fuselage, Lyc-360 powered tail dragger using the C-175 wings with the larger fuel tanks over the C-172 and tail surfaces. I never finished the design and bought the plans for the Bearhawk and started building.
Friend of mine used to have the C-175 with the constant speed prop, I think it was the last year, 1963. Very nice airplane.
 

Kyle Boatright

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What does a headwind (or tailwind) have to do with climb rate?
Let's say there is no wind at ground level, and you take off and climb at 70 knots indicated. But as you climb, the headwind increases to 10 knots. You maintain 70 knots indicated, but your groundspeed drops from 70 to 60 knots. You just converted 10 knots of horizontal momentum into additional climb rate. In extreme conditions, you can really skew your climb performance chart if you're building climb rate tables flying into increasing headwinds.
 

BBerson

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My 175 would take off in about 300 feet with flaps and climb at an extreme angle solo. I think it had a big seaplane prop.
 

skydawg

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Thanks for kind words Charlie.... we literally have about 100 calibrations/tunes we developed and often have different ones on each ECM, so would need to look up which were loaded at time of that video to get you a better answer RE BSFC #’s. We don’t Dyono each tune but you are correct that .33 would be more than efficient. The ECMs are programmed to go rich or leaner depending on a few circumstance, but high 3’s more likely depending on logic. The gear reduction also plays a part because the amplified torque to prop under a constant BSHP. At 8k DA with a max 210 tune would expect closer to 180 ish HP if that was the loaded tune. When we complete final tunes will have Dyno info and try to remember to drop you a line.

A c210 would be an ideal candidate for a V8 with an electric MT prop, and it would be easy to do. Not sure how far I will go commercialply with the project to make that happen as the liability in the US is really an obstacle.
 
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