Raptor Composite Aircraft

[Doggzilla]

No, those military vehicles use the very same engines they used before switching to JP-8. JP-8 wasn’t even introduced until 1978 and most of the engines are older than that.

They did not introduce an entire new series of engines just to handle the switch.

Jet fuel has far better lubrication properties than gasoline. If it was unsuitable then gasoline vehicles would have the same problems even worse. They do not.

 

[TFF]

Modern diesels may take jet but old ones will not; not available to the public. At the regional airline I worked at, we had as much of the drained fuel as we want. Watched a Ford, a Chevy, and a couple of Mercedes ruin the pumps. The ford guy went the farthest as he mixed with diesel and added oil to the mix. Had one friend adding 10% to his Taurus trying to eek out free mileage. He also built one of those brown gas generators. I could have had 3000 gallons at one swoop. Who has that home infrastructure? Had an aquatint from Germany who tried to run his jet Mini 500 helicopter on street diesel. It was one reason to build it. He said it smoked so much that he would have been a pollution target. I have run diesel on canola and once on ATF.

 

[Rik-]

A while back we had a discussion about how Jet fuel often causes Diesel engines to fail.

In college, I purchased a VW diesel rabbit. Thought what the hell, put Jet A in it and in about 3k miles later the engine was not so happy. Started to smoke a lot more, and eventually died. Pump was screwed best I could tell.

Short term it’s ok, but long term he will need an additive of some sort.

 

[pictsidhe]

No, those military vehicles use the very same engines they used before switching to JP-8. JP-8 wasn’t even introduced until 1978 and most of the engines are older than that.

They did not introduce an entire new series of engines just to handle the switch.

Jet fuel has far better lubrication properties than gasoline. If it was unsuitable then gasoline vehicles would have the same problems even worse. They do not.

The engines don't care, but the pumps do. Sorry, but many people have trashed their pumps trying to run on something other than diesel. I ran one car with a Bosch pump many, many ,miles on veg oil, which has plenty of lubricity. But it's successor had a pump from Joe Lucas (Prince of darkness), that was known for not tolerating the high viscosity of SVO, so back to diesel I went. Neither would have lasted long on Jet A. To run an old engine on Jet-A, you must have a compatible pump. That is not a major re-engineering effort. They bolt on... Or suitable additives, which may vary depending on your pump. Additives from your local hotrod store tend not to be up to scratch. Cars are built to run on the highly standardised diesel fuel available for them. Feed them something that they were not designed for, you may or may not be lucky. Military pumps are now built to run on more fuels.

 

[donjohnston]

According to a comment made by him on this latest video, he's planning on eliminating the pulleys completely and using a "sleeved cable" like motorcycles use for brake and clutch cables........

Just like on my Velocity. What a novel concept.

Although I think there's only one or two that have used a cable from the front of the cabin all the way to the aileron torque tube. Most have a cable from the back of the cabin to the aileron torque tube. And the new ones are doing push/pull tubes with no cables.

 

[AdrianS]

My boat is steered with a push-pull cable.
Much less hassle than the tension cable setup on the old boat - the pulley loads are surprisingly high - but quite heavy.

 

[pictsidhe]

Bellcranks for push/pull tubes and anchors for teleflex cables have the same rigidity requirements as cable pulleys. You need to be able to design stiff brackets for all of them. You should also be able to calculate the total system compliance and approximately know what it needs to be. Too soft, you can have flutter even during a taxi run, which is pretty extreme, but I can show you a video! Too stiff is too heavy. Airplanes are allergic to excess weight..

 

[Kyle Boatright]

https://www.youtube.com/post/UgyMXuQ1YgKM1517RAx4AaABCQ

No video today, but the link above takes you to a written Q&A Peter did on his Youtube channel. He indicates he's fixed all of the problems he's aware of. Personally, I don't like the redrive, and if there have been any real fixes, I missed them. He may have been able to fix rest of the stuff - I dunno. I do hope he's resolved the safety items. The weight and performance issues, well...

Sounds like our own Marc Zietlin, Elliott Seguin, and Justin (don't know his last name) are headed this way in the next week or so to inspect the aircraft in preparation for test flight. I'd love to be a fly on the wall for that.

 

[Marc Zeitlin]

No video today, but the link above takes you to a written Q&A Peter did on his Youtube channel... Sounds like our own Marc Zietlin, Elliott Seguin, and Justin (don't know his last name) are headed this way in the next week or so to inspect the aircraft in preparation for test flight. I'd love to be a fly on the wall for that.

Not sure where you got that link (which didn't work for me), but THIS:

https://www.youtube.com/channel/UCyEqCPjfEG1Cwt8-YEAOxbg/community​

is the one that leads to the Q&A comments.

As Peter has sort of outed us (personally, I think it's all TMI, but it's not my program, and there are a lot of "Marc"'s out there [too many, if you ask me], so what made you think that the "Marc" in his comment was me?), I can say that we'll be traveling to GA on Sunday, doing the aircraft design and physical review on Monday, all day. I'm coming home to CA on Tuesday. _IF_ things are acceptable after the examination, Justin and Elliot will stay and perform low speed taxi, high speed taxi, and flight test as the week progresses. My job, as I view it (and as I think the other three folks involved do) is to keep everyone alive and safe. That is, of course, THEIR job as well.

Since both Elliot and Justin's names are listed here:

https://www.airspacemag.com/flight-today/diy-jet-180963198/​

you can see what folks' last names are, if it matters. My name's spelled "Zeitlin", although to screw with telemarketers who ask, I tell them it's spelled "S" "M" "I" "T" "H", but they're all silent except for the "M", which is pronounced "Zeitlin".

After having been involved in a structural design review for Kittyhawk's Heaviside (with Justin, who's the chief test pilot for the program) a month ago, this will be an interesting juxtaposition.

 

[cheapracer]

and there are a lot of "Marc"'s out there [too many, if you ask me], .

Yup, but it keeps those who can spell and those who can't separated.

Regards,
Mark.

 

[Kyle Boatright]

there are a lot of "Marc"'s out there [too many, if you ask me], so what made you think that the "Marc" in his comment was me?).

"Marc is extremely experienced with evaluating canard aircraft. He does pre buy inspections on all types of canards."

You could call it brilliant deductive reasoning. But I'd just call it putting 2 and 2 together. ;-)

 

[BJC]

and there are a lot of "Marc"'s out there [too many, if you ask me],

Want to share your cull list with us?


BJC

 

[Turd Ferguson]

Keeping everyone alive and safe is no small order given not only the number of unproven concepts and practices but the fact that many of those concepts and practices will be working in concert. Incorporating Marc's large repository of explicit and tacit knowledge is certainly beneficial but jeez, Raptor has chosen to link many unknowns together and the proverbial chain is only as strong as the weakest link. In aviation, 'revolutionary' is best achieved through small increments.

Peter seems to have a growing sense of urgency to get the plane flying ASAP. Any discrepancy that will take more than a few days to rectify will likely be dismissed as unnecessary (recall how Len F's concerns would all be somewhat time consuming to resolve). It will be interesting to see if any showstopper discrepancies are found and how Peter will handle that. I have no doubt he has a plan "C" in mind.

 

[Mark Z]

We all know that Mark is spelled with a “k”.

 

[Venom]

https://www.youtube.com/post/UgyMXuQ1YgKM1517RAx4AaABCQ

.....He indicates he's fixed all of the problems he's aware of.....

Apparently a single ECU and an ECU software package that will, without notice, unilaterally pull the power are not as big a problem for Peter as they were for Len.

This guy is desperate.

 

[Turd Ferguson]

Len's concerns were 1)single channel ECU; 2)canard elevator on (slotted flap) tracks vs. simple hinge, and; 3)oversize winglets may cause dynamic with wing/aileron motion.

None of those items have been addressed. In his state of the union video, Peter blows them off as too complex to change.

 

[Venom]

Len's concerns were 1)single channel ECU; 2)canard elevator on (slotted flap) tracks vs. simple hinge, and; 3)oversize winglets may cause dynamic with wing/aileron motion.

Len's concerns were 1)single channel ECU; 2)canard elevator on (slotted flap) tracks vs. simple hinge, and; 3)oversize winglets may cause dynamic with wing/aileron motion.

None of those items have been addressed. In his state of the union video, Peter blows them off as too complex to change.

OK, understood. And your point is?

 

[cheapracer]

"3143lbs", what the heck?

Holy smoke, others have mentioned it here previously, but I sort of found it hard to believe, but now it's come from the horse's mouth ...

A 6 seat Cessna 206 is 2180lbs, a 1000lbs lighter.

I'll say it again, retracts, de-icing, pressurised, air-conditioning, auto-pilot, and all the rest of the bullshot frills have done nothing but waste money, cause the weight (and the wait) to increase, and impeded desperately needed flight development.

 

[Marc Zeitlin]

Len's concerns were 1)single channel ECU; 2)canard elevator on (slotted flap) tracks vs. simple hinge, and; 3)oversize winglets may cause dynamic with wing/aileron motion.

None of those items have been addressed. In his state of the union video, Peter blows them off as too complex to change.

One of those three has - Peter has long since discarded the "tracked flap" version of the elevators, and moved to a pivot hinge version (albeit the hinge point being WAY below the lower surface of the canard, sort of like the flaps on a Cirrus. The ECU is still single channel, and the winglet characterization as "oversize" is difficult to understand, IMO. ALL flight surfaces interact, and without a full GVT (which nobody in the EAB world does, really) there's no way to predict flutter without testing. There HAS been structural testing to compare FEA to wing/winglet stiffness, and my understanding is that the analysis matched with the testing reasonably closely IN THIS CASE.

So, one for three out of THESE three issues, with a ??? on the third, in my mind.

 

[Turd Ferguson]

One of those three has - Peter has long since discarded the "tracked flap" version of the elevators, and moved to a pivot hinge version (albeit the hinge point being WAY below the lower surface of the canard, sort of like the flaps on a Cirrus.

Is that for the same reason? So he will theoretically have adequate elevator control if he chooses to add flaps later?