It sounded like the engine issue would have resolved by going to idle. He made it sound like the pilot put the throttle right out of the idle detent where it didn't have FADEC idle protection and it didn't have enough power to run the load. As the pilot said, the easy fix is a/c off on final until they work something else out.

OTOH, if the ECU was properly configured it would maintain the minimum idle speed of higher regardless of the throttle position. One has to wonder what other little quirks lurk in there.

OTOH, if the ECU was properly configured it would maintain the minimum idle speed of higher regardless of the throttle position. One has to wonder what other little quirks lurk in there.

From what I remember in the video it seemed like for the rpm bump to happen then the throttle (er, power lever or some nomenclature) had to be on the idle stop. In my head I'm considering a few possibilities in how the sensors and inputs all work together when the engine is in a car (I'm guessing a modern "drive by wire" system that is carefully matched to an automatic transmission, including sensors and inputs to that) as compared to the installation in Raptor. I wonder what's different on the airplane or how the ECU works differently than the computer when the engine is in the car.


I know at least a few old fashioned methods to make this rpm bump happen in a gasoline engine, and they all involve either the throttle position or some kind of idle air controller, and either electro-mechanical logic or electronic/computerized logic. I have no idea if what this engine does is related to any of them or if it's something completely different.



What you, Lance, and Michael are all suggesting about more surprises around the corner and needing to farm out more of the engine work to an experienced tuner... I think that would be the conservative way to do it and it would be a safe, sure bet. I get the idea that the money is tight and that's why it hasn't happened this way.

Let’s keep in mind, Peter used a website to pick the turbos. He watched a webinar on tuning. It hasn’t been on a dyno. It’s blowing smoke part of the time. His EGT probes aren’t at each cylinder’s exhaust. He has no clue what the temperature is coming out. Where he did have them, EGTs were getting up to 1800 F and he was completely okay with it. He theorized that at the exhaust, the EGTs are low enough. He didn’t have time to move the probes.

It’s not about piling on him just for fun.

Wouldn’t it have been cheaper to just source parts from the velocity XL?

I’m so intrigued by this project. I can’t stop reading these posts and watching the videos. Good for him for trying. Way more work than I thought it would be.

One of the explicit purposes of the experimental amateur-built category is "education and recreation" (§21.191(g)), and this project certainly has that in droves. The scope and complexity of it is a heck of a lot for one person to bite off and chew... to put it mildly.

Like you said, good on him for having the guts to try, but holy moly, it is a lot of different things to get right!

One man’s “guts” is another’s “hubris.” Jim Bede was an accomplished engineer and aircraft designer (and huckster) when he set the homebuilt world on fire with the BD-12 and -14. One prototype flew in ground effect once and the whole project was shelved. In this case, Bede used a well-established engine in a novel configuration. That change alone was responsible for long delays in construction though, IIRC, the design was scuttled because it was uncontrollable.

I don’t know, but I get the impression Peter has none of Bede’s prior experience. Unfortunately, he’s gaining Bede’s reputation in business.

There’s a saying in homebuilt boats: before you build the boat that’ll sail you around the world, build its dinghy. Maybe, instead of designing the ultimate Velocity, he should’ve started with the ultimate Volksplane.

I think his failure odds would have been cut drastically if he'd tried to prove either a novel airframe or a novel powerplant. But he's doing both at the same time, and it's overwhelming the project.

IMHO, he should have actually built a Velocity.

Then design and build his plane with some knowledge of the build process. But use an established aircraft engine.

Once he had some flight characteristic data, he could have built a second airframe applying modifications learned from airframe #1 and put the new powerplant on that one.

But he is where he is.

I can't help but compare with the guy putting the corvette engine on the murphy moose.
He wanted to do something novel with the powerplant so he selected proven, no-frills airframe design and changed it as little as possible for what he wanted to do.

That's a good point- and when it comes to using "other people's money" then you have to walk a fine line between managing the investors' expectations (with truthful communication) and raising sufficient funds.

There's nothing intrinsically wrong with the project taking one year or stretching out over twenty, just as long as the people sending you the money stay happy.

Ideally, you deliver a product in the end...

He is running a MOTEC computer which is high end motorsports ECU. He can setup a command so that when the A/C or fans trigger, it sends a signal to IAC motor to bump the rpm to offset the load. I've watched enough of his videos to know he doesn't really have the background to be doing what he's attempting without some type of proper engineering support and its all starting to bite him in the a$$ now. I don't bother watching his videos anymore, its a train wreck in slow motion.

For safety’s sake - I’m sure happy he’s at the bigger airport.

His radio voice sucks tho.

New video with several taxi runs down the 8000' runway at Valdosta. I'll be surprised if Wasabi doesn't at least get a couple of flights in. Brave dudes.