Chinese v-twin diesel.

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,194
Location
US
Feasible to aim an IR "thermometer" close to the giubo (or whatever the damper is) with a cockpit readout during testing? At least ground testing? It might show which RPMs the giubo is working hardest/absorbing the most heat. If forced air cooling is deemed appropriate, the thermometer could let you know if it is being effective.
 
Last edited:

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
455
Location
San Rafael, California
Thanks Bill, I get that but what I don't get is these French guys are using three or four different diesels with different ratio redrives and none are having the problems I keep reading about here. I'm getting close to flying so would like to understand why theory and practice isn't aligned here.
Never, accept what an armchair pontificator says over real life results and facts.

If the planes are flying and everyone is fat and happy then this is worth more than anything you will read from the armchair professionals on here.
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
8,935
Location
KWHP, Los Angeles CA, USA
Never, accept what an armchair pontificator says over real life results and facts.

If the planes are flying and everyone is fat and happy then this is worth more than anything you will read from the armchair professionals on here.
What about if the "pontificator" is a scientist or engineer with XYZ number of years' experience studying, testing, and designing around these real life results and facts and known physics? Is that pontificator's opinion or guidance any less valid because he is sitting in an armchair when he pontificates?

If one of the people flying these engines in France makes a statement on the internet, while sitting in his armchair, does the armchair somehow invalidate his facts?
 

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
455
Location
San Rafael, California
What about if the "pontificator" is a scientist or engineer with XYZ number of years' experience studying, testing, and designing around these real life results and facts and known physics? Is that pontificator's opinion or guidance any less valid because he is sitting in an armchair when he pontificates?

If one of the people flying these engines in France makes a statement on the internet, while sitting in his armchair, does the armchair somehow invalidate his facts?
Well as Edison would say, what have you done vs what others are actually doing?

Don't be afraid to tell someone that something won't work simply because you don't have the ability to make it work as there's lots of experts saying things would never work all the while there are people providing that it does.

We are not talking some ponzi scheme here.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
278
"Planes flying, people fat and happy" does not scientifically select an acceptable sample size, nor select the method for testing and statistical analysis of the various hypotheses of whether the diesels flying in France are acceptable for the various complaints above.

If such acceptable testing is completed, and peer reviewed, THEN the arm chair "pontificator" who considers themselves a scientist or engineer has evidence to start changing their mind.

Being an armchair scientist or engineer pontificating is not grounds for dismissal, especially with all the modern tools and data access available. With modern tools, they will often be more right than the people actually testing. They can virtually test more variables faster.

Once receiving tested and reviewed real world results, a good engineer or scientist modifies their tools and predicted results so they can virtually predict the real world again.

The best modern results require real world scientifically designed testing and peer review. Get that and force some change.
 
Last edited:

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
1,371
Location
SC
Never, accept what an armchair pontificator says over real life results and facts.
I don't know much, but I know that anyone that's followed Billski for any length of time would know that the man knows whereof he speaks.
 

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
455
Location
San Rafael, California
I don't know much, but I know that anyone that's followed Billski for any length of time would know that the man knows whereof he speaks.
I'm confused, are you saying that something that is currently working is not working in reality due to the comments or thoughts of a member on here?

Facts speak louder than thoughts.
 

Niels

Well-Known Member
Joined
Aug 15, 2019
Messages
86
Is there any reason to believe that torsional and other vibrations behave different in flight than in a stationary test rig?
 

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
1,371
Location
SC
I'm confused,
Apparently so. Because something "works" doesn't preclude that it works as well as it possibly could and that all the possible errors have been eliminated. Processes evolve all the time because highly intelligent people seek to improve upon what is "working."

I digress ... I'll leave you to your thoughts ...
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,941
Location
Saline Michigan
Feasible to aim an IR "thermometer" close to the giubo (or whatever the damper is) with a cockpit readout during testing? At least ground testing? It might show which RPMs the giubo is working hardest/absorbing the most heat. If forced air cooling is deemed appropriate, the thermometer could let you know if it is being effective.
It might work. Does the IR thermometer get messed up if the surface you are trying to read is moving or only there part time?
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,941
Location
Saline Michigan
Is there any reason to believe that torsional and other vibrations behave different in flight than in a stationary test rig?
TV is one of those things that does work equally fine on a stand and in flight. Other stuff like gyroscopic moments need a pretty fancy stand to be properly tested...
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,941
Location
Saline Michigan
I don't know much, but I know that anyone that's followed Billski for any length of time would know that the man knows whereof he speaks.
Near as I could tell, the posts so far were still in the hypothetical regime. ;) I don't pontificate from an armchair, so I KNOW I was not being insulted.

As to my being too theoretical, I do put a lot of value in field data, and I did spend a bunch of time on the topic with real production engines, transmissions, drivelines, dynos, and vehicles rolling along a road. Solved a bunch of problems along the way too. Even fixed a real problem with a prop turning Jabiriu powered system that had scarred the heck out of its test rig with broken parts flailing about. If something has a fleet history, whether good or bad, that speaks volumes.

My big worry is in getting from building the first one to getting a dozen installs to 250 flight hours each. That is where the risk lies, and why I am such a proponent of doing the engineering up front and then confirming it is OK with a TV measurement system before anyone flies the thing. A bunch of test stand hours with it run over the entire operating range helps a bunch too.

Billski
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,194
Location
US
It might work. Does the IR thermometer get messed up if the surface you are trying to read is moving or only there part time?
The inexpensive consumer models I'm familiar with just use a lens to focus the incoming IR radiation on a thermopile. By comparing the temp of the thermopile to ambient temp (another sensor in the unit), and making assumptions about the emissivity of the target surface, it can determine the temperature of the observed field.
The assumed emissivity is normally pretty high (.9 or more), so the actual surface temps will be a lot higher than the measured temps if the surface has low emissivity (chrome, etc). Lab quality units let you calibrate the units for a specific emissivity.
A target surface moving normal to the IR thermometer won't affect things. Theoretically, a surface moving toward the thermometer would have shorter (higher energy) radiation due to Doppler effects, but our giubo's speed will be too small relative to C to make a difference.
If the target surface wasn't visible to the thermometer for the entire sample period, it would affect the accuracy of the reading. In practice, I don't know how long the observation period typically is, we'd probably need to find real tech literature on the unit.
How they can make and sell devices that do this for $20 is amazing. Infrared Laser Thermometer. (Disregard the laser, it has nothing to do with temperature sensing. It just shows where the device is pointed, and looks high-tech.)
 
Last edited:

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,941
Location
Saline Michigan
Knowing that, you could still map the temps over the range of rpm looking for the high temp, then refine the search. After that, run the engine at the worst spot until it goes steady state, shut down and get the actual temp. If temps are safe you are good to go. If temps are too high, you know what you are have to get after...

Billski
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,194
Location
US
Knowing that, you could still map the temps over the range of rpm looking for the high temp, then refine the search. After that, run the engine at the worst spot until it goes steady state, shut down and get the actual temp. If temps are safe you are good to go. If temps are too high, you know what you are have to get after...

Billski
Yes, I was thinking maybe step through the RPM range in 200 rpm increments from idle to redline, 3 minutes per step (to give giubo temp time to stabilize under new conditions). From 700 rpm to 4800 RPM would take about an hour and a quarter. Then, go back and look at the questionable spots a little harder.
 

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
455
Location
San Rafael, California
Apparently so. Because something "works" doesn't preclude that it works as well as it possibly could and that all the possible errors have been eliminated. Processes evolve all the time because highly intelligent people seek to improve upon what is "working."

I digress ... I'll leave you to your thoughts ...
Your a special kind aren't you? If you are attempting to twist statements, please do better. There's a difference between saying it will not happen and it actually happening.

Who is to judge customer satisfaction? You? Me or the customer?
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,194
Location
US
Some folks go weeks or months between visits to HBA. It is a blessing. Then, they return.

Brood X cicadas stay gone for 17 years.

If only....
 
Last edited:

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
1,371
Location
SC
Some folks go weeks or months between visits to HBA. It is a blessing. Then, they return.

Brood X cicadas stay gone for 17 years.

If only....

It's reported that we will have more than our share this year ... seems to be starting already! From the article:

A few individuals will probably come out in mid-to-late April, Day said, stragglers that the entomologist nicknames "lonesome Bobs," who call and call to no avail.


 

bifft

Well-Known Member
Joined
Apr 17, 2011
Messages
310
Location
Utah
If the target surface wasn't visible to the thermometer for the entire sample period, it would affect the accuracy of the reading. In practice, I don't know how long the observation period typically is, we'd probably need to find real tech literature on the unit.
Spending a lot of time fooling around with one in the kitchen when cooking I think the observation period is 0.25 seconds or so. I would expect to get an average of the blocked and exposed period over that range.
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
8,935
Location
KWHP, Los Angeles CA, USA
Rik, we are all entitled to our opinions, and this is by definition an "armchair" type of discussion forum. But let me put a little perspective on this, if you will be kind enough to allow it.

I want to tell you a story about this particular discussion subject, "torsional vibration". You see, I'm a world class expert on torsional vibration... one of the top experts in the entire world. Not a scientific or theoretical expert, not an engineering expert, and not even a mechanical expert. What I am an expert on is the subject of family funerals that were directly caused by torsional vibration.

Tom Hastings was a friend of mine. He was a mechanical engineer and machine designer for Haas CNC, a 40+ year pilot, a Viet Nam era US Marine veteran, husband, father, and grandfather. He had built a beautiful Cirrus VK-30, with the IO-550 engine and the 6 or 8 foot long drive shaft, and the MT prop at the back.

The airplane had flown for a long time, something like 10 years and over a thousand hours. The key point here is that just about anybody could have easily said "it must be working, he's got a thousand hours on it, all you armchair pontificators don't know what you're talking about".

But because of torsional vibration and/or resonance or whatever, the drive shaft did let go, and when it did it took out the primary elevator and rudder controls of the airplane. Tom, his daughter Amber, Amber's fiancee', and Amber's 4 year old girl Madison were lost on the way home from a family vacation. He was unable to control the flight path or attitude of the airplane, and even though he had plenty of altitude to get the airplane onto a local highway or a nearby golf course, it flew into bad terrain and a large power line tower structure.

So my big point here is that there are plenty of things in airplanes that are simple and obvious. Cotter Pins, safety wire, oil pressure, balancing the controls of a high speed airplane. But there are also many areas that are far from simple, and require a lot of formal training and experimentation to really master. The hard part is that some of these complex things can be just fine for a while, and then let go, leaving you without a paddle. Because of this, a lot of people can get pretty irritated when generalized sweeping comments are made without reasonable backup.

Is the J-3 Cub a good airplane? Yes, there are thousands of them flying for 80 years, and hundreds of thousands of pilots can't be wrong.

Is the drive shaft on the VK-30 safe? Apparently it is for some period of time, but that time might be five minutes or ten years. Does that warrant investigation beyond a quick dismissive comment about armchair experts? I believe so.

 
Top