Different engines possible?

Morne · #1 05-08-11, 09:02 PM

Quote:

Originally Posted by hharney

http://www.aviationclassifieds.com/a...337A+Skymaster
550 on one end
360 on the other
3 blade
2 blade
One of a kind

THAT is what I am talking about!

Kind of a "best of both worlds" there. All the oomph you'd ever want, plus the ability to fly fairly economically at altitude.

Heck, even the paint job on that thing is cute!

Roger · #2 05-08-11, 10:27 PM

I've always had a bit of a problem with various "rocket scientists" scabbing "better ideas" onto Skymasters. Inevitably the scabbed on projects either fail to live up to the hype, or end up literally crashing and burning into yet another pile of metal. Then organizations like the FAA look at the model accident history, and lump the scabbed together "Spendiculous Skymasters" which have crashed or bent, into the data set with regular Skymasters. We "regular Skymaster" drivers are then left holding the bag with potential decreased value of our aircraft and increased inspection expense, due to errant cause and effect accident determinations, and subsequent buyer misconceptions.

I'm all for people trying new and exciting things to make a "better wheel" but the FAA should change the designation of all aircraft that have been modified to something like :LIYOH (Life In Your Own Hands) and then drop all of those aircraft accidents from the regular aircraft database.

Put a turbine on a Cub, but don't call it a Cub in the accident database when the wings fly off.

Ernie Martin · #3 05-09-11, 12:31 AM

For a different reason, I couldn't agree more with Roger.

I have an MS in engineering from Caltech, spent 30 years in the aerospace industry and have consulted for both GE and the FAA. And one thing missing from any discussion in this Message Board -- not just this thread but the whole Message Board -- is "Systems Engineering". The aircraft as a whole is a "system". Everything is interelated. It was designed as a system. Change one item and it affects everything else. Often adversely. Change the engine and it affects the loads on the airframe, on the prop, on the prop governor -- maybe even the harness.

None of us has the money or resources to make sure that a change in one area will not adversely affect another area. So it doesn't get checked. Or it gets checked poorly.

I read this thread when it started and I wanted to jump in and say "are you crazy?" I didn't because I'm one of the site administrators and did not want to discourage full discourse. But now that Roger voiced his views I wanted to say "save not only the money but also the grief".

Before I went into engineering I spent five years in a business that souped up cars for racing. The typical client had limited resources. So he changed the carb from a 2-barrel to a 4-barrel. Never was the desired performance achieved. The compression ratio, cam timing, valve size and exhaust system -- which were designed for the 2-barrel -- remained, so there was now lots of fuel but the combustion efficiency sucked. Even clients who modified the whole engine ended up unhappy. Yes, the engine was a rocket but the drivetrain (transmission, rear axle, etc.) was designed for the wimpy engine, so elements of it kept failing.

Your safest aircraft is a well maintained certified aircraft. Limit your changes to the avionics suite.

Ernie

Morne · #4 05-09-11, 02:54 PM

Quote:

Originally Posted by Ernie Martin

Your safest aircraft is a well maintained certified aircraft.

Ernie, I appreciate your point of view, but hasn't the 550 been STC'ed for the Skymaster? Thus, isn't a Skymaster with a 550, be it one or both engines, still certified?

As to other ideas, like diesel, again I'm talking about once it has been STC'ed. I have no desire to be a test pilot. The diesel thing, addressed more thoroughly in its own thread, is a longterm option for dealing with the 100LL problem.

I don't have a MS in Mechanical, but I am a degreed engineer. I worked as a Metallurgist for a fortune 500 aerospace OEM for most of my career. Seeing the differences between the various revisions of "same model" commercial and military aircraft makes your point for you - just because the F-18C/D and F-18E/F look alike DOES NOT mean they are the same from an engineering standpoint! Ditto all the various tweaks of the 747, you can't pull a landing gear from a -100 and use it on a -400.

So I fully understand and respect your point about playing around with a time proven airframe. Further, I have great respect for the "nostalgia factor" associated with a "complete correct" specimen of an older vehicle, be it a classic car or a classic plane. But what I remain uncertain of is whether or not you are attacking the entire STC process in general?

Certainly there are STC modifications that are better than others. For instance, I never liked the "tip tanks" and wouldn't buy a Skymaster with them. But there are also a WHOLE BUNCH of STCs that are just fine.

Just curious where you're drawing the line, here.

WebMaster · #5 05-09-11, 06:29 PM

Quote:

Originally Posted by Morne

Ernie, I appreciate your point of view, but hasn't the 550 been STC'ed for the Skymaster? Thus, isn't a Skymaster with a 550, be it one or both engines, still certified?

Just curious where you're drawing the line, here.

Only one company has certified the 550's in a Skymaster, and that is AirScan. The STC is for only their aircraft. The STC can not be purchased, or used on other aircraft. They also did an STC for gross weight increase, but that one is also proprietary to their aircraft.

AirScan operates a fleet of Skymasters. For more information on them, I suggest Google.

Morne · #6 05-10-11, 03:08 PM

Quote:

Originally Posted by larry bowdish

Only one company has certified the 550's in a Skymaster, and that is AirScan. The STC is for only their aircraft. The STC can not be purchased, or used on other aircraft. They also did an STC for gross weight increase, but that one is also proprietary to their aircraft.

AirScan operates a fleet of Skymasters. For more information on them, I suggest Google.

A very germane point. Certainly the particular bird cited in this thread is not an AirScan unit, so it is not covered by the STC. As previously stated, I don't want to be a test pilot.

Tropical's implications are intriguing to me, but this isn't really the proper venue to discuss them.

Likewise, I'm sure Ernie and I could chat for hours about all the different mods out there and whether or not they are any good. I'd especially enjoy discussing the tip tanks, but again this isn't the proper venue.

So unless someone hears about AirScan selling off their birds, that sort of closes this topic.

hharney · #7 05-10-11, 10:52 PM

The original first engine mod was Riley Super Skyrocket. These are well proven aircraft with a valid STC. I don't know how many were converted but I would guess around 20 or so. The STC is for sale (or was) and is still a valid STC. I have spoken to owners of the Super Skyrocket and they seem to love them. Just like we love our original Skymasters. I am sure they had some quirks like everything does, even our originals.

So just to recap the discussion there are really several STC engine conversions. Riley, AirScan, Aviation Enterprises, and I probably am missing at least one. TF Hawk has their diesel conversion and it's an STC.

Mods for aircraft in the form of STC's were to improve the aircraft not to make them more dangerous. There are some really good STC mods for our aircraft out there. There may be some that were not tried and tested as others but that is another story. There are many, thousands of hours of safe flying with mods on Skymasters as well as hundreds of other aircraft.