Quantcast

Raptor Composite Aircraft

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Status
Not open for further replies.

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,220
Location
Saline Michigan
So here's question: After watching the latest video with the duct taped dam in front of the static port on the bottom of the fuselage.

Is it possible to put a static port on the bottom of the fuselage (or wing)? I always assumed that on the bottom of the wing would be subject to high pressure and the same (to a point) for the bottom of the fuselage. Also would be subject to variations in pressure due to changes in AOA.

In all the static ports I've looked at, I've never seen one on the bottom of the plane. Always on the side of the fuselage (or on a pitot tube mast).
It does look like a place where it will see errors based upon g loading and angle of attack.
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,964
Location
Port Townsend WA
That hop has zero value in this aircraft's flight program.
Nope. He proved it didn't go out of control. He needs to do it again a bit higher.
I think that air dam ahead of the static hole is like a cowl flap. It makes a low pressure 😀
 
Last edited:

Steve C

Well-Known Member
Joined
Oct 6, 2008
Messages
158
Location
Lodi, CA
One of ours gave PM a lot of grief about not having reliable numbers to go from. As he accelerates, the altirude starts climbing as much as 100 feet, indicating the static port is in the wrong place. PM made his usual dismissive response, but then we see in the next video a taped on mini cowl flap, which likely made it worse.

After his comments about stagnant air on the flat side of a 172 and "flow", I don't rhink he understands pressure at all.
 

HomeBuilt101

Well-Known Member
Joined
Oct 20, 2015
Messages
332
Location
Aguila AZ
The Celera 500L is certainly interesting...

Way back in college we did aerodynamics and they had us design and airplane that when finished looked exactly like a DC-9 so someone must have reverse engineered it and then gave us the parameters and we "engineered" it. I really do not know much about the courses except that one day I came to the realization that I had used every button the scientific calculator including the clear button...and that is exactly what I did after graduating...I pretty much cleared out all of my memory from those days...

What we did not do in those courses was perform a marketing analysis of an aircraft design nor did we do any production planning for mass production, parts reduction strategy, labor cost reduction, and other stuff that gets an idea from the drafting table (we had tables back then) to the market place and be profitable in the process.

So the Celera 500L looks very interesting however from a "regular Joe" perspective it does not "look" like it will fly nor dies it look like it will have great market appeal because it just looks too big and expensive to operate.

The Raptor on the other hand does indeed "look"like it can fly and it does seem to fit an needed market niche in that each family in the US as we all know has exactly 2.3 children so the Raptor if it flew looks like it can take the kids and the dogs for a weekend trip and I suspect that there are more than 12 people like me out there who think it could "work".

So yes PM is a know it all type who does not listen...got it...and that is too bad because sadly his dream is fading because of his personality.

There are a great deal of smart people on this forum who have a great deal of real world, aviation, production, maintenance, and even aircraft marketing experience so it would be interesting to hear your opinions on...

Lets say PM got you all together in the same company and said to you (like he did say on his website) "I think the general aviation market is under-served in the need for a 5 place very roomy, sporty looking airplane that could fly the (formally) typical American family of two parents and 2.3 kids and they have two pets. One parent needs to use the airplane for business trips with one or two people onboard so it should fly 2000 miles on one tank then when fully loaded with all five seats and bags it can still takeoff with half tanks. It will be launched as a kit with "fast build support" and then some time later it will be certified...Oh and I will provide the resources but will stay of of the way".

So the above certainly sounds like what he wanted to do but it seems he went down a certain road that looks to be a dead end road.

What would you all do to get this dream to final production?
 

FTEstudent

Member
Joined
Aug 27, 2020
Messages
15
SW's CFD module isn't at the level that would provide accurate answers in the regimes of interest (IMO).
Coming from academic background with CFD experience, you are absolutely correct, Solidwork's CFD is inaccurate for detailed aerospace applications. No aircraft manufacturer uses this software for CFD.

So all his performance numbers he claims that he thinks it will be more efficient than the SR-22 are innacurate, the ones that are drag and lift dependent.
 

FTEstudent

Member
Joined
Aug 27, 2020
Messages
15
Interesting find..
Peter claims on his website "estimated takeoff distance 1100ft", well looking at one of his old videos and counting the stripes and correlating with google maps I calculated the raptor used 1850ft of runway to reach 80kts. Now obviously idk if that's max acceleration but he was doing high speed taxi so I can only assume it was (this was at Cherokee airport). Just shows his estimates are way off...and the SR-22T published takeoff distance is 822 ft
youtube video I referenced
 

flyboy2160

Well-Known Member
Joined
May 25, 2014
Messages
351
Location
california, USA
...SW's CFD module isn't at the level that would provide accurate answers in the regimes of interest (IMO)...
Coming from academic background with CFD experience, you are absolutely correct, Solidwork's CFD is inaccurate for detailed aerospace applications. No aircraft manufacturer uses this software for CFD...
Solidworks has two versions of CFD software: a simple one that is free (CosmosFlow?) with the mechanical seat and an expensive one called Flowsim (which is actually a product called Nika/FloEFD.)

If you guys are dissing the free version, I can't argue because I've never used it.

However, I have used the Nika/FloEFD version and confirmed by wind tunnel and by flight test correlation its exceptional accuracy in a couple of cases that left other CFD software well off the correct answer. It gives exceptional accuracy for drag off bluff bodies with a high separation angle. It is less accurate for separated flow at lower separation angles, but it did give reasonably accurate lift and drag for one study a NACA airfoil. (I will find a link to that analysis of a NACA airfoil and post it later.)

The other case in which it gives exceptional accuracy is for boundary layer flow very close to a surface. It gave excellent correlation to tunnel and to flight test data for the optical distortion over sensor windows caused by very, very small differences in the boundary layer over the windows. (My cells were ~.020" to .030") The optical engineers were stunned at how well the optical distortion predicted using the Flowsim results matched the recorded tunnel and flight test data.

 

Attachments

Last edited:

lelievre12

Well-Known Member
HBA Supporter
Joined
Jul 15, 2020
Messages
49
I can see how PM went down this track. The inspiration for the cross country machine is logical in its desire to reach altitude and thinner air.

My P210 gets great cruise numbers the higher I fly. HOWEVER the TSIO520 burns around 28GPH in the climb and that climb rate is pretty lethargic at ~400FPM. (less at alt). Therefore even to climb to 23,000 (my ceiling on the P210) will take ~ 1 hour and burn more than 35 gallons (including takeoff at 37GPH) or 210# of fuel. And the climb speed is slower at ~120KIAS so that hour is spent going slowly. So before you get to 'cruise fast' you spend a long long time getting up high.

I could climb faster however the engine gets hotter and busts my personal CHT limit of 390F in climb easily. The Vitatoe TN550 conversion solves these issues but then burns ~40GPH in the climb all the way up. Even more fuel!! So the limitations of Avgas engines are clear. They are extremely inefficient at climb power as so much fuel is used for cooling, not power.

On most trips (flights of less than 3 hours) the whole thing is a bust and makes no sense whatsoever. And so I never climb that high. Usually only to 16.5K or 17.5K.

The TDi 'Raptor' vision is better in that the engine is burning a much lower 21 GPH at full power and I guess would average around 17GPH (119#) all the way up to alt. Even assuming the climb rate is no better the my porky 4000# P210, the 300HP TDi fuel burn would be around 90# less just for the climb.

So if the idea is to get up high and go fast, then TDi makes sense. At 30,000 feet an airframe only needs 142KIAS to see 230KTAS. I can achieve that KIAS in the P210 with around 65% power (200HP) and so I expect a slippery canard would require no more at similar MTOW.

So I am a big fan of the concept, not because cruise rates are any better, but mainly because climb performance should be far better. I only write this in order that we can stay focused on the 'why' of this project as we all debate the 'what'. It's still a worthy concept despite its obvious engineering challenges.
 
Last edited:

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
360
Location
Downham Market, Norfolk, UK.
Latest on PM YT Channel.
What load would the front tire take without bursting.🤔

Raptor Aircraft

17 hours ago
What you need to understand is that while on the gear the nose/canard has about 480lbs on it with me on board. Once the main wing starts to develop lift, because the center of lift is aft of the main gear, a lot more weight transfers onto the nose/canard. In level flight it will be about 1100lbs. The reason I'm trying to get the aircraft to lift off on it's own at 90 knots is because at that speed with a slight nose up the 1100lbs is already on the nose because the main wing is almost taking all the weight off the main gear. If I go slower the nose is much lighter and will come up more readily because there's still so much weight on the main gear. So, given this scenario, once the mains lift off and all the weight is being carried by the wing and canard there's no little to chance of the nose rapidly rotating higher. If anything it's more likely to settle down because it's just not supporting that 1100lbs. By the way, I know it's 1100lbs because I weighed the nose when I had the wings blocked at the center of lift. So, now that you understand what's going on with the weight transfer you should come to the same conclusion that the way I'm bringing the aircraft into ground effect at 90 knots is in fact a reasonable procedure.
 

Kyle Boatright

Well-Known Member
HBA Supporter
Joined
Nov 11, 2012
Messages
1,066
Location
Marietta, GA
Latest on PM YT Channel.
What load would the front tire take without bursting.🤔
Raptor Aircraft
17 hours ago
What you need to understand is that while on the gear the nose/canard has about 480lbs on it with me on board. Once the main wing starts to develop lift, because the center of lift is aft of the main gear, a lot more weight transfers onto the nose/canard. In level flight it will be about 1100lbs. The reason I'm trying to get the aircraft to lift off on it's own at 90 knots is because at that speed with a slight nose up the 1100lbs is already on the nose because the main wing is almost taking all the weight off the main gear. If I go slower the nose is much lighter and will come up more readily because there's still so much weight on the main gear. So, given this scenario, once the mains lift off and all the weight is being carried by the wing and canard there's no little to chance of the nose rapidly rotating higher. If anything it's more likely to settle down because it's just not supporting that 1100lbs. By the way, I know it's 1100lbs because I weighed the nose when I had the wings blocked at the center of lift. So, now that you understand what's going on with the weight transfer you should come to the same conclusion that the way I'm bringing the aircraft into ground effect at 90 knots is in fact a reasonable procedure.
Somebody doesn't have the foggiest regarding canard aerodynamics.
 
Status
Not open for further replies.
Top