Quantcast

10/23 Raptor Video

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

5761RF

Member
Joined
Nov 26, 2020
Messages
14
Right. He can do whatever is needed for this research version. He may only want to get a bit more cooling to get to the cooler altitudes. Nobody knows what the testing goals are. It may be limited to winter flights only.
Calling Muller's deeply flawed aircraft a "research version" is a bit silly. That implies there has been a disciplined and documented effort to establish flight capability baselines, investigation into aerodynamic and propulsion characteristics, and methodical exploration of system improvements in an effort to optimize the aircraft and meet the performance goals claimed at its introduction to the public. What has taken place up to now is the complete opposite of these basic tenets of research.

Adding a "bit more cooling" will not solve the problem. As @wsimpso1 and others have shown by performing calculations based on some known and some assumed factors, the heat rejection system is wholly inadequate.

The solutions proposed by @wsimpso1, @Voidhawk9 and others, completely removing the existing heat rejection system and starting over, appears to be the only viable remedy. Muller's crude characterization of these recommendations as "mansplaining" illustrates his inability to recognize factually accurate calculations and valid observations while he basks in the glory of sycophantic commentary extolling his insight and talents as his creation nears its release to his adoring public.
 
Last edited:

malte

Well-Known Member
Joined
Feb 5, 2011
Messages
121
Location
Flensburg / Germany
[...]

The builder in question didn't design or sew it himself, so you treat it like a seat belt. Buy one good enough, install per directions, strictly, carefully, and hope you never need it.
[...]
The builder still needs to apply due diligence and an understanding of the load paths and balance of the aircraft. I don't want to brake forum rules, but we're still talking about PM, right? There has been a notable accident with a WT-9 in Germany, where the chute has pulled the airframe apart and the pilot has fallen without chute with one half of the airframe, and the flight instructor came down with the rest of the aircraft. Investigation showed that the chute had almost just rescued the engine and propeller, but not the rest of the airframe: https://www.bfu-web.de/DE/Publikationen/Untersuchungsberichte/2002/Bericht_02_3X046-0.pdf?__blob=publicationFile

Testing a whole airframe chute is highly likely to destroy the craft, even if everything works perfectly. The odds of personal injury are very high. So that's pretty much the Final flight test of a prototype, after everything else is fixed.
You don't need to test the whole aircraft, but you should at least test the structure that needs to be penetrated. There have been accidents where the chute has been damaged by sharp edges of carbon structures and those where the rocket could not penetrate the structure, rendering the chute useless. These test can be made with a mockup of the structure, though.
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,668
Location
Saline Michigan
Additional cooling adds weight. What's the solution?
I say air cooling.
Well, yeah. Many of us would choose a big turbocharged Lycoming as is already applied in pressurized birds for this application.

There are all manner of water cooled 300+ hp engines running well in airplanes. It can be done, and at suitable weights. It just has not been done here.

The point of my previous post is that while PM is scheming out little changes in cooling, the Raptor really must have BIG changes so that it can be test flown at anything resembling its capabilities. Until then it is being flown with modest power and by a pilot distracted by combination of a continuous overheat emergency and a continuous pitch/yaw/roll oscillation. Not a well posed problem for documenting and sorting an airplane...

None of this even gets into the competing issue of induction/exhaust/intercooling also needing redesign. Cowling will get crowded indeed during the redesign...

Billski
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
14,467
Location
Port Townsend WA
The point of my previous post is that while PM is scheming out little changes in cooling, the Raptor really must have BIG changes so that it can be test flown at anything resembling its capabilities
He said he doesn't want big cooling changes with this one. His test program and business goals remains a mystery, but he did say he might redo it with flaps. So it might stay in research for a long time. :)
 

PPLOnly

Well-Known Member
Joined
Dec 12, 2020
Messages
73
Re: whole airframe parachute testing.

You go on faith it works and preflight with the manual in hand.

The builder in question didn't design or sew it himself, so you treat it like a seat belt. Buy one good enough, install per directions, strictly, carefully, and hope you never need it.

Testing a whole airframe chute is highly likely to destroy the craft, even if everything works perfectly. The odds of personal injury are very high. So that's pretty much the Final flight test of a prototype, after everything else is fixed.

There's a reason in pre-critter-safety days they used animals in ejection seat development. The film I really want to see is how they strapped a Bear into a seat. Did they strap it in, then install the seat w/Bear? Or hoisted the Bear up into the plane and strapped him in? What tranquilizers? Custom jock straps for ground crew? ;)

You can non-destructively test the parachute (An easy to see example is Mike Patey testing it in his cub) with a ground deployment. And he’s not building this plane for himself but for production. That means he needs to be willing to test certain things to destruction. He should have done it with the engine and drive system at the very least. He’s conserving a prototype at the expense of reliability data for a new type jn my opinion.
 

Aesquire

Well-Known Member
Joined
Jul 28, 2014
Messages
2,557
Location
Rochester, NY, USA
You can ground test the chute, sure. It's airframe integration that you really need to test. A ground shot would let you verify the tear away parts...tear away. And the other little details that mean the difference between a wild ride, and a much shorter one where some would be calling to complain.

Ideally, you use a fuselage that has been "used up" by static testing of engine mounts or other structure, but still has the intact parts where you plan to run the suspension straps and mounting points.

But flight testing of a chute system? I still think it's near the last thing you do... and the current flight test prototype would be ideal for it, seems to be overweight and many other issues, from the browsing of these threads. :)
 

231TC

Well-Known Member
Joined
Aug 29, 2020
Messages
104
That simulated go around was interesting. Not a bad idea to want to know it could do it. I doubted it. But he didn't get in landing configuration, gear down and slowed to 110 or whatever his crazy approach speed is. Opposite direction from his takeoff for this flight, so presumably downwind although that could have flipped or been calm. He used 80% power because he couldn't use more. He traveled over a mile while climbing the first 200 feet. Looks like he would clear the trees in a late go around so that's good to know, but not an impressive result overall. Because of the way he does things, it didn't provide a very reliable picture. But it's something.
 

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
456
Location
Downham Market, Norfolk, UK.
I think we all despair at the way Raptor Guys approaches the self induced problems, Rather than junking 1/2 ton, or empty Cessna 150 weight, to get stall/landing speed down, he possibly plans to retro-fit a flap system?? and the cooling system needs a total rethink from scratch, but at least he keeps us entertained in these strange times., so we must thank him for that. If i wasn't watching and commenting on his YT Channel her indoors would have me painting the bedrooms, 🤪
 

TarDevil

Well-Known Member
Joined
Jun 29, 2010
Messages
823
Location
Coastal North Carolina/USA
So, from earlier discussions in the old Raptor thread, I was under the impression that "cooling" could be achieved if the engine was set up properly, in particular the turbos. No?
 

rv6ejguy

Well-Known Member
Joined
Jun 26, 2012
Messages
4,086
Location
Calgary, Alberta, Canada
So, from earlier discussions in the old Raptor thread, I was under the impression that "cooling" could be achieved if the engine was set up properly, in particular the turbos. No?
The turbos are a minor issue at low altitude and low power settings currently being used. There is simply a fundamental lack of oil and coolant heat dissipation happening with the current kludged setup and as Bill pointed out, it's nowhere near being able to climb to 25,000 feet on a hot summer day at full gross, at climb power.

His attempt at increasing oil cooling using the hot cowling air didn't work as predicted. His oil temps still reached 250F. I understand he's revised that now to flow ambient air through the new oil cooler.
 

Voidhawk9

Well-Known Member
HBA Supporter
Joined
Mar 26, 2012
Messages
466
Location
Timaru, NZ
I was under the impression that "cooling" could be achieved if the engine was set up properly, in particular the turbos. No?
No, two separate issues, though they were for a time inter-related: Initially, the hot air from the intercooler was being blown onto the coolant radiator. He has since added a diverter so that the heated air from the intercooler is diverted away from the coolant rad, which helped some. But so has flying in the cool evening air.

In the latest video, he claims that the turbo sizing does not matter because he does not need to eliminate turbo lag, and that whatever they are, they will compound. See prior discussion on this topic if you are unsure about that.

He did manage to climb to almost 5,000ft (at around 300-400FPM).

Landed at 84kts, which he noted that he found uncomfortably slow.

Apparently, substantial changes have been made since this flight, presumably to the cooling system.
 

Victor Bravo

Well-Known Member
HBA Supporter
Joined
Jul 30, 2014
Messages
8,447
Location
KWHP, Los Angeles CA, USA
Flaps on the main wing will require flaps on the canard. The complexities and additional flight loads on the control systems and structures are probably pretty significant.
 

rv6ejguy

Well-Known Member
Joined
Jun 26, 2012
Messages
4,086
Location
Calgary, Alberta, Canada
Peter's comments about the turbos being properly matched are nonsense. Compound turbos NEVER use the same compressor sizes. One more thing he just doesn't comprehend no matter if you try to educate him or not.

The structure is still flexing around sometimes, given he says this was smooth air. The cameras show this multiple times. There is also a tremor in the aircraft as he pulls the rpm back, again can see it in the cameras.
 

231TC

Well-Known Member
Joined
Aug 29, 2020
Messages
104
In the latest video, he claims that the turbo sizing does not matter because he does not need to eliminate turbo lag, and that whatever they are, they will compound. See prior discussion on this topic if you are unsure about that.
Yep, all this time and he's still clueless about compound turbos. I'm far from an expert, but learned a ton about the basics from the prior discussions.

Apparently, substantial changes have been made since this flight, presumably to the cooling system.
Next flight after this video was only 16 minutes. Over 5 days ago and it hasn't flown since. Can't wait to see what these substantial changes are he's talking about in the narration, but has not yet flown with.
 
Top