Where'd that 90% estimate come from? Is there some study showing that if one finds a disbond in a layup (and this is a disbond, not a delamination - let's be clear on terminology) that there's a 90% chance that you'll find another one?If there is a delimination at this place, there is a 90% probability that there will be delamintions elsewhere...
So in this case, the disbond is probably caused by an extremely poor choice of location for aileron hard stops (at the aileron, rather than in the control circuit upstream of the aileron). Pull hard on the stick, put stress on the wing skin bond joint at the hard stop. So a disbond here is only an indication of a lack of understanding of aircraft control system design, not an indication that the fabricators did a poor job of bonding the plane together.and that the glue fillets are insufficient. Did he do bag load testing?
I read every post; have done for four years or however long it has been now, and I was (until 2 weeks ago) one of the people with a deposit in escrow (I cancelled without any argument from Peter BTW). I think these comments are spot on. My opinion, is that the truth is in the middle between some of the more extreme viewpoints. On this forum they tend to be very negative at times but the balanced engineering and technical expertise is what I come back for almost every day. I respect Peter for not doing the stupid thing and trying to fly the plane. I also admire that even though he absolutely knew that he wasn't going to like stuff, he was good for Wasabi to post anyway. I hold out hope that those molds will perhaps at some point lead to a lighter and better version of the Velocity - I think we all want that.To be quite fair to Peter while he is showing the positive outlook on all this from his side, I think he's earnestly showing his side of the story. He's unaware of the best or "proper" way to solve a lot of these issues, he's learning as he goes, and while sometimes he acts incredulous at the need for certain tasks he does eventually seem to do them and it seems he tends to come away from those experiences satisfied in the outcome having been worthwhile.
His positive outlook lately has been strained by all the reality catching up, the things he's learning, and I think bit by bit he's starting to get some of it just by being faced with the bill of it all. The lack of experience and knowledge really clearly comes through when seen from the Wasabi video, but it makes plain that he's not so much intentionally hiding the bad stuff, because he simply doesn't know what's bad and should be hidden.
When he has all these deep complicated explanations for how certain things that should just work all have their certain way of making it work, it's clear he's worked it out in his head that it all makes sense and that specific thing might be slightly odd but it works fine; but I don't think he has taken the moment to step back and reflect on all of those quirks in aggregate and whether they add up to the type of machine someone wants to jump into. He's gotta explain every little thing and justify it. He doesn't see that as an issue cuz he has lived with all this knowledge for years. And one or two quirks is probably fine. But everything here has things that just don't quite work right, and so while it works-ish. it's all clearly half-finished prototype stage solutions. And in retrospect when there's a better design worked out (hopefully) he'll clearly see how far he had to go.
But that's the future.
But somewhere I think he knows there are big gaps in his personal experience, which is why despite all of his hubris at times, he still knows enough (I want to hope) to continue to defer to people with experience and real critical eyes when it comes to flying the thing, and has to have inside his mind at least a bit of the real concern that the creature may bite.
It's for jet engines! Diesel engines evolved with a fuel that is a fair lubricant. Jet A has poor lubricity, so diesel pumps that need a certain level of Iubrication are prone to siezing up. Jet A also does not have a controlled cetane number, another important specification for diesel useage.What exactly is wrong with Jet A?
Jet A, House Heating Oil, Kerosene and Diesel #1 are all the same exact fluid.It's for jet engines! Diesel engines evolved with a fuel that is a fair lubricant. Jet A has poor lubricity, so diesel pumps that need a certain level of Iubrication are prone to siezing up. Jet A also does not have a controlled cetane number, another important specification for diesel useage.
It would be very useful if someone could research an additive package to 'dieselise' Jet A. May take some dollars, though.
Actual lay up of the carbon fiber is the one place in the project where Peter had someone doing the work that actually knew what they were doing.Thanks for the delamination/disbond clarification.
Instinctively I was worrying about wrong surface treatment or contamination pre bonding or insufficient fillets. An issue frequently neglected. A wrong peel ply or some other factor and you have the structure significantly weakened.
He bounced it pretty good when he slammed it back onto the runway! That's gotta be worth something. After all the wings didn't fall off.Actual lay up of the carbon fiber is the one place in the project where Peter had someone doing the work that actually knew what they were doing.
and no nothing was sand bag tested, drop tested, or any other kind of tested beyond running up and down the runway at 80+kts
Here is what and why I know this to be true.They are most certainly not the same. Do you really think that oil refiners would use a specific cetane cut and add lubricant additives to kerosene or heating oil? I haven't played with Jet-A, buy I believe that it is pretty close to kerosene. Kerosene is noticeably thinner and less lubricious than diesel. It also smells different, especially when burned. People can spot kero burning diesel cars by the smell. I would mix it with 10% biodiesel, which is very slippy stuff.
I've seen several people kill their pumps with pure kero.
Wow! I drove a Diesel Rabbit about 225,000 miles, but it didn’t take close to 500,000 gallons.I've purchased over 500,000 gallons of Jet A and used it in my VW Diesel Rabbit
The fuel was for the boat, but if I'm low, the pump flows what the pump flowsWow! I drove a Diesel Rabbit about 225,000 miles, but it didn’t take close to 500,000 gallons.
I burned lots of Jet A in industrial boilers back in the early 1980’s at dirt cheap prices. The fuel terminal had take-or-pay contracts for Jet A, the airlines weren’t burning much, more fuel was in transit, so it was cheaper that either natural gas of Number 2 fuel oil. No problems.
If you want an "insured fuel" Jet A is going to be the route if you are flying. If you are land based application then it doesn't matter as it's just a price issue not a product difference.different additives will destroy different seals.
Science and politics promote the use of different additives in the different named fuels.
It is my experience that at times all three fuels delivered to my village originate from the same pump, however if they have a customer requiring the newer diesel (with additives for newer diesel engines) that they have to rinse their tanks before delivering jet fuel as it will destroy the seals in our turbine engines.
For the most part I understand the underlying fuel will burn for most of the 3 main purposes (jet/turbine, diesel engine and heaters) but the wrong one in any given system could destroy the seals and or pumps. Those delivering the fuel know what is on the work order as well as the real life end use for the fuel and should ensure that the fuel they deliver is compatible with its end use as well as communicating the reality of the standards of the actual fuel being delivered.
(I am not directly involved in any of this except to receive the fuel for our village generators, so accept my experience with a grain of salt)