A64Pilot Posted April 15, 2022 Report Posted April 15, 2022 (edited) 16 hours ago, carusoam said: My only run in with Joe Brown of Hartzell… A decade ago… I had to buy a new prop for my plane… The spinner came in the wrong dimension… They didn’t have the right dimension to match the Mooney cowling… Hartzell told me they would let me know when the right one was available… I can hardly wait to find out if that will be covered under warranty or not… Mooneys are all about aerodynamic efficiency… from nose to tail… Mine starts out with a 90° step right on the nose… about 1/4”… It’s lovingly referred to as the Hartzell step… Soooo….. If you know Joe Brown… Casually ask him if they ever got a spinner about a 1/2” larger in diameter for the Long Body Mooney’s… Its a bit annoying at pre-flight time… it doesn’t look right… it’s not aerodynamic… It looks like a sag, but up close everything is nicely aligned… My contact at Hartzell was Mike Trudeau… Project was about a decade ago… The words “built on honor” make me want to finish this project… Best regards, -a- Three blade on my Maule was just the opposite, it was slightly larger, looked goofy, same prop was used on several aircraft so I’m sure they picked a spinner diameter and just went with it. Only once did I get Hartzell to develop a prop from scratch, and then only because I told Joe that the Avia three blade outperformed his. That started him sending me different props, everything from three blade 106” to four blade 108”, nothing could beat the Avia, so he sent down someone who measured the Avia. I was told they couldn’t build a copy of the Avia as it’s blade profiles made for heavier blades and Hartzell didn’t have a hub that could stand the Centripetal force, so they built a 108” four blade prop blades from scratch to outperform the Avia which it did, what made it work apparently was it was heavily tip loaded. Most turbine props aren’t designed to work well at crop duster speeds and air density. Guy name Igor Brunchillik or similar owned some of Avia, and he is a really nice guy, that Gerd guy that owns MT owns part of Avia also, him I wouldn’t invite over to my house. Little guy has quite the Napoleon complex. But Igor is a good guy, you can’t make that name up:) Not sure you can really see it here, but the spinner is taller than the cowl Edited April 15, 2022 by A64Pilot Quote
Yetti Posted April 15, 2022 Report Posted April 15, 2022 33 minutes ago, A64Pilot said: Hank got it, temp is temp. Way back in the late 70’s I used to build and drag race turbo bikes. One trick I learned was to dial in a lot of valve overlap, we could do that easily as motor was twin cam and we adjusted cam timing by slotting the chain sprockets that drove the cams. This caused fuel and air to be blown into the exhaust and at first glance would seem to waste boost, but fuel burning in the exhaust system, plus the engine was a lot more burning fuel, which made the turbo spool up much faster. It literally fried the chrome on the exhaust, burning fuel in an exhaust isn’t normal, at night I swear you could almost see through the headers. Prior to that I experimented with Nitrous oxide that would be turned off with a pressure switch once boost built. As you can imagine cool down on a turbo drag bike wasn’t happening so we ran a special pure synthetic oil, at the world finals in Mississippi we broke a chain and that broke the case dumping the special oil, so I built the motor that night and not having anything else used Castrol 20w-50, well guess what? the Castrol showed less wear on the center section bearing, I’d take apart the turbo after each race weekend and replace the bearing, which was easy and cheap, but once the bearing wore, then the compressor would make contact with its housing, trashing both. We ran almost zero clearance between the two, clearance was adjusted by shim washers under the compressor wheel https://www.dragbike.com/star-racing-george-and-jackie-bryce-build-a-small-motorcycle-speed-shop-into-a-drag-racing-institution/ It was Star Cycle back then and our expertise was in building Kawasaki Z1 turbo bikes, I was there 79 and 80. Point of this is to try to say I like turbo’s and have a little experience with them did your bikes have forced air cooling with low pressure and high pressure areas? I don't think we are discussing the turbos, rather the cooling dynamics of the environment where the turbos are operated. Quote
A64Pilot Posted April 15, 2022 Report Posted April 15, 2022 (edited) 5 minutes ago, Yetti said: did your bikes have forced air cooling with low pressure and high pressure areas? I don't think we are discussing the turbos, rather the cooling dynamics of the environment where the turbos are operated. No, and the turbo on your aircraft isn’t air cooled either, it’s oil cooled, notice the absence of cooling fins like the cylinders and heads have? Lots of the engine is in fact oil cooled, pistons, crankshaft, cam etc. The oil itself is air cooled of course, by a cooler with fins Edited April 15, 2022 by A64Pilot Quote
carusoam Posted April 15, 2022 Report Posted April 15, 2022 Calling @Blue on Top… (interesting plane design question…) How much effort goes into matching the prop’s spinner to the cowl design, and engine placement… As delivered… my Mooney M20R had a perfect match between the prop spinner, and the cowling… as if they were designed together… After prop replacement from Hartzell, different manufacturer, the new spinner is smaller in diameter and is a mismatch to the cowl… The gap between spinner and cowl is in MMs… Does the cowling designer pick a stock spinner, and design around it? Or design the cowl to standard dimensions and design a spinner to match? How do I get a Hartzell spinner to better match my plane’s cowling? Kind of a quirky aerodynamics kind of question… For plane designers… Best regards, -a- Quote
A64Pilot Posted April 15, 2022 Report Posted April 15, 2022 (edited) We matched the cowling to the spinner, that’s how you get a perfect fit Edited April 15, 2022 by A64Pilot 1 Quote
Blue on Top Posted April 20, 2022 Report Posted April 20, 2022 On 4/15/2022 at 2:29 PM, carusoam said: Calling @Blue on Top… (interesting plane design question…) How much effort goes into matching the prop’s spinner to the cowl design, and engine placement… As delivered… my Mooney M20R had a perfect match between the prop spinner, and the cowling… as if they were designed together… After prop replacement from Hartzell, different manufacturer, the new spinner is smaller in diameter and is a mismatch to the cowl… The gap between spinner and cowl is in MMs… Does the cowling designer pick a stock spinner, and design around it? Or design the cowl to standard dimensions and design a spinner to match? How do I get a Hartzell spinner to better match my plane’s cowling? Kind of a quirky aerodynamics kind of question… For plane designers… Best regards, -a- As @A64Pilot mentioned, we match cowing to spinner ... but we design the spinner, too. On a piston airplane it cannot be as tight as shown on the turboprop above as a piston engine moves a lot more (there are are actually design gap minimums. Gaps hurt aerodynamic performance a lot. Cooling drag and efficiency is actually changed by the spinner and inboard (hub) end of the propeller design. In other words, Hartzell and McCauley propellers will not cool the engine the same. BIG spinners are good; propellers get in the way (and move the flow slightly). Another point most people don't realize is that cowlings are not symmetrical. Engines are typically offset about 2 degrees right and 2 degrees nose down to account for cruise torque, etc. and aligning thrust in pitch more in cruise. The first several inches to a foot of the cowling are not symmetrical. Sometimes inlet openings are slightly different sizes. Different airplanes will also change where the cant angles are made from. Most OEMs today will center the front face of the propeller hub on the centerline of the airplane ... but not all. This also means the engine mount is not symmetrical either . The list of little things goes on and on and ... 1 Quote
Shadrach Posted April 20, 2022 Report Posted April 20, 2022 (edited) On 4/14/2022 at 7:54 PM, A64Pilot said: Carusoam The article you referenced shows EGT / TIT, and lots of irrelevant data like fuel flow and CHT, but none of that data is relevant. It does not show turbo center section temp, and is therefore not worth much, the only relevant number, center section temp, is missing, and it’s incredibly easy to get, a simple thermocouple connected to the center section and a multi-meter and you have relevant data, but that wasn’t done. Why? Why do you think Hartzell went through all the trouble to make that Video? I can tell you why, it’s because of people like you linked to getting people to not follow the manufactures instructions nor the POH. Why else would Hartzell bother? They did it to prevent premature Turbo failures is why I’m glad he’s not destroyed a turbo, but that doesn’t mean he has a working system anymore than the guys I know that regularly slip a Cessna with flaps. Sure if you come out of the flight levels at low power and never go back to cruise power, then sure the center section is probably cool, but notice in the video Hartzell points out that if you go above 1200 RPM even for a short time, the clock resets. 1200 RPM is very low power, not nearly enough to maintain flight So how many people actually shoot the entire approach and landing at very low power, never increasing it? Power lower than a 1200 RPM idle. What is it with people who think the engine manufactures are fools and their favorite internet social influencer is the one with the real knowledge? Every Farmer, OTR Truck driver etc knows to idle to cool the turbo, more modern cars don’t need it because their center sections are water cooled and never get hot enough to need it, but aircraft are not of course. Oh, LOP EGT is usually higher than ROP EGT, so running LOP isn’t helping to cool the turbo Lots to unpack here. Deakin's graph has a lot of relevant information if you’re interested in how all of these different systems affect one another and how they change during each phase of flight. Deakin is not just making stuff up; by way of his association with APS, George Braly and Walt Atkinson (RIP), He has/had access to one of the most sophisticated Aeroengine test stands in the country. Every single one of them agrees that Idle cool-down is useless and adds heat to the Turbo in most cases. Bob Kromer (Mooney test pilot) wrote the attached email which was posted to Beechtalk many years ago. The email clearly shows he agrees with their stance based on his real world experience with the test data from M20Ks flight tested with thermocouple equipped turbochargers. Also, I think that comparing an Aeroengine that has been loafing in descent to a Farm implement or Semi that has been in heavy use is a poor operational comparison. I have no dog in the fight as all of my turbos are on ground vehicles. I will say that neither John Deakin nor Bob Kromer are the type of man to just make random recommendations without supporting data, especially when they contradict the POH. Turbo.pdf Edited April 20, 2022 by Shadrach 3 1 Quote
thinwing Posted May 9, 2022 Report Posted May 9, 2022 the only temp i can actually manage is TIT....and I notice it is lowest upon touch down but than a 1/2 mile taxi and turn arround its back up to 950 plus...idling for about 5 min sometimes less it drops back down to the low 700s.It takes a real leap of faith to pull up to the hangar and just shut down.So according to Deakin..I am causing early turbo wear...but I am currently at 1450 hrs on this airresearch(garret?) and can detect no noticable bearing roughness,unusal runout,squealing noises .(I check this every 25 hr oil change by loosing clamp to compressor duct to intercooler and hand spin the compressor wheel )ive had to rebuild the wastegate due to an actuator oil seal leak and when i sent this out to Gary Main I asked him what best practice re turbo cool down.He advised just keep what im doing ,.but coking is more of a design issue of how the turbine shaft housing with their bearings are supplied with oil.He feels my airresearch turbo is particularly robust...I think he said the bearings are actually ceramic..The smaller units in the twin turbo continentals were according to him less than robust maybe due to smaller physical size.I dont really know..but hes the guy that repairs them in Calif. Quote
Fly Boomer Posted May 9, 2022 Report Posted May 9, 2022 17 minutes ago, thinwing said: idling for about 5 min See Bob Kromer doc in previous post. 1 Quote
thinwing Posted May 10, 2022 Report Posted May 10, 2022 21 hours ago, Fly Boomer said: See Bob Kromer doc in previous post. Does Bob Kromer repair turbos? 1 Quote
Fly Boomer Posted May 10, 2022 Report Posted May 10, 2022 1 hour ago, thinwing said: Does Bob Kromer repair turbos? Test pilot. And he has flown Mooneys with instrumented turbochargers. And his data suggests idling on the ground to "cool the turbo" may not be good. And by not "cooling off the turbo", it may last longer. That last sentence may be my own deduction. 1 Quote
alexz Posted May 11, 2022 Report Posted May 11, 2022 According to mechanic from MSC it is not manly to "cool" the turbo but to remove excessive oil turbo tank drain so it does not gum up. At least on TIO-540-AF1B. Quote
carusoam Posted May 11, 2022 Report Posted May 11, 2022 7 minutes ago, alexz said: According to mechanic from MSC it is not manly to "cool" the turbo but to remove excessive oil turbo tank drain so it does not gum up. At least on TIO-540-AF1B. Spell check… More manly to Not cool the turbo? +1 Bob Kromer’s writing skills…. I own a Mooney because I read what Bob wrote about the M20C… he covered the topic nicely… all technical, no fluff…. Stuff that can be relied upon… Pp thoughts only, -a- 1 Quote
StevenL757 Posted May 11, 2022 Report Posted May 11, 2022 On 4/14/2022 at 11:05 PM, carusoam said: My contact at Hartzell was Mike Trudeau… Project was about a decade ago… The words “built on honor” make me want to finish this project… Nice shout-out. Advance apologies for the unsolicited comments but throughout the 10+ years I’ve known Mike, he’s been extremely generous with his phone time and has ALWAYS been willing to have a robust conversation about the history of the company, and the many things they have going on (well, almost everything). Mike, Bob Minnis, and Brian Kendrick worked together to get me my first Acclaim Type-S 7498 prop in 2014. Bob worked with him extensively on the STC as a DER, among other roles. Talk about having the A-Team working with you. Having forgotten more than I’ll ever learn about propellers, Mike is a wealth of knowledge and experience, and always has a good story whenever you talk to him. He’s one of those rare people where you can always hear his level of excitement rise whenever you get him talking about what he does. To me, that’s a sign of someone who genuinely cares about the people he leads, the product he produces, and the customers he serves. A true class act. Look up “Built on Honor” in the dictionary, and it wouldn’t surprise me to find his picture. 1 Quote
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