speedracer
Well-Known Member
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- Feb 4, 2020
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- 82
LongEZ's and Varieze's don't stall so as long as the rules use the word "stall" instead of the words "minimum flight speed" they should be exempt, right?
10/23 Raptor Video
- Thread starter Volzalum
- Start date
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If trying this trick/tactic, I'd assume the regulatory agent would point out that the canard >does< stall. If the reg doesn't say ”stall of the primary lifting surface" then you'd be in a grey area and I think I can tell you right now how that would turn out.
Flyfalcons
Member
How would a reasonable person interperet the rule?
ImperfectSense
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- Oct 1, 2020
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- 41
The lowest speed at which the aircraft can maintain altitude? That seems to be the ultimate practical limit. In other words... how fast will you be going when you hit the wooden house with the family of 4 in it?
Kiwi303
Well-Known Member
The actual wording used is as follows :
"...aircraft whose stall speed in the landing configuration at maximum gross weight does not exceed 45 Knots..."
Given a canard if designed well "Stalls" by the canard loosing lift, the nose dropping, speed picking up due to nose down attitude and reaching airflow sufficient to allow lift again. This is separate from excessive high AOA climb stalls discussed earlier in the thread.
So stall or no stall, the minimum flight speed of the Varieze/LongEZ is above the required landing configuration stall speed of the NZ microlight rules. If you can't get your plane down to 45 Kt or below it's not going to pass muster.
I'm only up to page 70 of this saga, and so far it still looks like PM isn't trusting his design enough to conduct minimum flight speed tests to find where the stall speed of the canard is on the Raptor, or even if the rear wing goes first or not. But at 4 seats and over 600Kg it's moot for me, it will never make microlight rules here.
p.s.
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Kiwi303
Well-Known Member
Easy. import a few container loads from Europe.
Don't be so parochial as to overlook globalization of supply chains.
WINGITIS
Well-Known Member
Peter's arrogance on display again in the comments section: "Well, I thought I made it obvious that it's working as required without any other changes required."
We're expecting a broken airplane but hoping for a safe escape for the pilot.
It was working as required. Or better than the original steel collar.
Someone mentioned the bearings might overheat if they have seals on both sides. I don't know if they do or not or if that is an error for him to correct.
Someone mentioned the bearings might overheat if they have seals on both sides. I don't know if they do or not or if that is an error for him to correct.
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JayKoit
Well-Known Member
I'd like to hear from some of the torsional vibration experts on here... when he hits full power he says the violent shaking is the prop wash hitting the camera on a gimbal - and that he can't feel that sitting in the cabin...but the way the sound changes as well leads me to believe there truly is something unsettling going on at that RPM?
ImperfectSense
Active Member
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- Oct 1, 2020
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Oh my lordy.... smh
Raptor Aircraft
2 hours ago
The wing isn't vibrating. The gimbal in the camera is being affected directly by the prop wake.
Raptor Aircraft
2 hours ago
The wing isn't vibrating. The gimbal in the camera is being affected directly by the prop wake.
ImperfectSense
Active Member
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- Oct 1, 2020
- Messages
- 41
I'm not vibration expert... but I have mounted a lot of GoPros on a lot of WWII warbirds. Those aircraft often shake like _crazy_ compared to new stuff, especially aircraft with big radials. Our B-25.... well let's just say it's pretty challenging to get clear video if there are any parts of the aircraft in the shot, if your camera mount has any flexibility in it at all. But what his camera does when he gets the prop up to 2400rpm is beyond anything I've ever experienced. It looks to me like whatever vibration is being passed down the wing, up the GoPro mount, and into the camera, is hitting some critical frequency within the internal mechanism of the camera itself. I totally disagree with his implication that it's some sort of software or control issue of the GoPro, I think the GoPro is simply being shaken to death.
So much wasted effort and cost.
He did not even need to make a new "collar". Take the existing one, cut seal grooves and install scarf cut Teflon seals acquired from a local auto transmission shop (they can help you find a part that is oversize, then trim with an Exacto), and fit two bronze bearings for a suitable sliding fit to pilot the "collar", then bore for a tiny clearance through out except for the bearings. The seals will hold pressure and leak enough oil to keep the bearings alive. Done, and it works on MILLIONS of automatic trannies built every year.
Just watched the video. Being as he made the new "collar" out of bronze, he could have made that the bearing material too. But no, he installed a couple of sealed ball bearings to pilot the collar on the shaft. Hmmm. With nothing holding the inner race to the shaft, the inner race is likely to slide at a speed in between the collar and shaft speeds, and maybe gall and then stick to the shaft. That sealed ball bearing might be OK at these speeds and modest loads, but without the oil in the bearings being turned over, it could overheat. You would need the part number and an estimate of the loads and then go to the maker's catalog to see if the bearing will be OK as a sealed unit.
Now as to the vibration, who knows? Something goes into resonance with some vibe that ramps up and down with engine rpm. Engines make vibration, and we can not know what is vibrating with it, but we do know that whatever it is (wing, wing and tip sail, wing and tip sail and camera on its mount, just the camera on the mount) it gets big at max rpm, and it seems to go through another mode at lower rpm too. Might be the same mode when the engine is at half the speed of the max rpm setting, might be a different forcing function, might even be a different vibe mode.
I would sure want to put a little accelerometer or three on the wing near the camera, on the engine, and on the firewall near one of the mount bolts, just for starters. If the airframe vibe takes off at those power settings, that could be an issue. On the other hand if the wing and tip sail do not go vibe crazy, just the camera and its mount, well, might lose a camera.
Billski
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Wanttaja
Well-Known Member
Sorry to change the subject, but I've found the new "Hypersmooth" function on the GoPro 8s and higher to be pretty good at eliminating shaking. Here's a side-by side comparison of the old GoPro 5 and the new models:
Ron Wanttaja
rv6ejguy
Well-Known Member
Not prop wake affecting the camera. Another absurd hypothesis from Peter. I've mounted lots of cameras on planes, never seen (or heard) anything like this. This all showed up with the new engine fitted and I mentioned it previously. The vibration signature has changed from before. I'd want to investigate why.
No TV study done on this drive he wants to sell to customers- scary. He has no clue about TV and is asking for trouble down the road. Just because you can't feel it doesn't mean TV isn't about to snap something. The human body becomes less sensitive to vibration as frequency increases and is not a very reliable gauge in this scenario.
Something in the propulsion system is exciting the wing structure to do that.
No TV study done on this drive he wants to sell to customers- scary. He has no clue about TV and is asking for trouble down the road. Just because you can't feel it doesn't mean TV isn't about to snap something. The human body becomes less sensitive to vibration as frequency increases and is not a very reliable gauge in this scenario.
Something in the propulsion system is exciting the wing structure to do that.
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slociviccoupe
Well-Known Member
Im not going to say funny because no laughing matter. But there are plenty of sealing type devicrs used in transmissions that accomplish this. The seal rings in bmw/getrag dual clutch transmission im working on has everything he needs already made.
Attachments
slociviccoupe
Well-Known Member
Even engine plain bearings would work. You just account for the percentage of oil leak from them. Look at variable valve timing , they use just the cam journals to supply oil to ports in the cam thay advance or retard the cam gear and it works fine. If he copied that system it would work. At this point a simple mechanic is smarter at implementing something than a claimed engineer.
And those have to stay dry on the other side. Good parts, but it would take luck at a phenomenal level to have COTS hard seals like that fit his shaft size. He could have just "borrowed" the dimensions and used those parts in first place...
The preferred way is to put grooves either in the shaft or on a sleeve that is pressed on the shaft, fit solid ring glass filled Teflon seals that can only barely be stretched over the shaft, then size the seals down with a conical tool. Then the sleeve can cylindrical, of modest precision, and the plain bearings at each end bored for a good journal bearing fit. Next best uses seals lathe cut from an extruded tube and a scarf cut made to split them so they will fit over shaft easily - they leak more than the solid rings, but you can find a suitable seal that is a little big by talking to your nearby tranny shop, then scarf cut it until it fits. Both solid and scarf cut hold pressure nicely and leak a little to cool and lube the journal bearings.
Given Raptor's solid shaft and case design, you have to build the seal set inside out, but since the sleeve is stationary, that works fine. It does mean the machine shop has to cut the seal grooves in the bore of the sleeve, but they are already cutting the flow and drain paths in the bore.
So it goes,
Billski
rv6ejguy
Well-Known Member
Peter isn't a mechanical engineer and has no mechanical background to speak of prior to Raptor. His multiple design failures on numerous parts of this airplane show why he is out of his league here. It keeps biting him over and over. He needs professional help (the engineering kind) if he ever wants this thing to succeed (into production).
Eventually his trial and error, TLAR approach and his continual brushing off of serious legitimate concerns is going to lead to more failures at best or tragedy at the worst. No way this PSRU as is, will make it into the production airplane and that goes along with many other parts of Raptor as well. It needs nothing less than a complete design review from top to bottom by real engineers and a 2nd prototype to validate the hundreds of changes required to make it a safe and viable production kit airplane for the masses.
Production can't start from what it is now and anyone who thinks so, is delusional. It's miles away from the original specs which were in themselves, highly improbable from the start. Even with a proper propulsion system and a 1200 pound weight reduction, it will still fall short of existing 20+ year old designs such as Velocity and Lancair. The physics will get you every time with that 62 inch wide fuselage...
Eventually his trial and error, TLAR approach and his continual brushing off of serious legitimate concerns is going to lead to more failures at best or tragedy at the worst. No way this PSRU as is, will make it into the production airplane and that goes along with many other parts of Raptor as well. It needs nothing less than a complete design review from top to bottom by real engineers and a 2nd prototype to validate the hundreds of changes required to make it a safe and viable production kit airplane for the masses.
Production can't start from what it is now and anyone who thinks so, is delusional. It's miles away from the original specs which were in themselves, highly improbable from the start. Even with a proper propulsion system and a 1200 pound weight reduction, it will still fall short of existing 20+ year old designs such as Velocity and Lancair. The physics will get you every time with that 62 inch wide fuselage...
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"At this point a simple mechanic is smarter at implementing something than a claimed engineer."
He doesn't claim to be an engineer or mechanic.
He doesn't claim to be an engineer or mechanic.
