Quantcast

Raptor Composite Aircraft

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,584
Location
Port Townsend WA
Well, he may give up on this project and move to something different with more experience under his belt.
The Klapmeier brothers certainly must have ignored most of the experts as well with that first plane. Remember the VK-30? It was a pusher. It was five seats and powered with an auto engine. It had a prop shaft. What expert would say that was a sales winner?
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,232
Location
Australian
Does CAD calculate weight?
Some do, some don't, but as far as I know, they all give surface area, which makes it simple to calculate/estimate the parts weight, knowing the general thickness, with a number of online weight calculators covering various materials. It's certainly how I do it, and quite accurate.

In my case I add a couple of % to allow for the rivets weight and/or welds. My builds are always within a couple of pounds of computed weight, usually under.

Anyway, why isn't each component being weighed and a running tally kept?

If you go back through the comments on his YT vids, you'll see that several of us tried that. Peter almost always ignored our suggestions. And here we are.
You know he blocks most critics on Youtube?

Make a comment, log out, and see if you can see your posts while logged out.
 

Hot Wings

Grumpy Cynic
HBA Supporter
Log Member
Joined
Nov 14, 2009
Messages
7,197
Location
Rocky Mountains
Peter as much as said that he didn't know how to get weight estimates out of Solidworks, so never tried.
I find that quite odd given the skill he seems to have with other features of SW. My first class in SW used the finished weight of the part for the grade of that particular assignment. It's just 3 clicks to assign a material and 2 to calculate the mass properties.
 

Rod Schneider

Active Member
Joined
Jan 11, 2013
Messages
31
Location
Ball Ground, GA. About 40 miles north of Atlanta
I don't have an engineering degree, but I have been an A&P for 42 years. I'm also at the same airport as the Raptor, and have seen it up close on many occasions and have talked with Peter numerous times. He's a nice enough guy to talk to, but he has a hard time accepting suggestions. When he first brought the project to the airport I went down to look at it, and I've even actually helped him with some things, mostly assembling and installing the latest revision of the prop reduction drive. The airplane is very complex, especially the powerplant, with a lot of things that need better securing/routing to avoid future problems. I've pretty much stopped going down there, and I don't want my name associated in any way with this project. When he first talked about doing high speed taxiing on the runway, I tried to talk him out of doing that unless he was prepared for an inadvertent first flight. His response was "I'll be careful"........ When he was advised that he needed to install EGT probes at each cylinder's exhaust to get a better idea of what the EGT actually was, his response was "I don't have time to do that". At that point, I quit helping him. I really hope that no one gets hurt testing this thing, but it concerns me.
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,306
Location
Thunder Bay
The other night I was watching the latest Raptor video and saw an interesting reality check, maybe for every project. The first video suggested in the side bar was another of Peter’s called something like “Ready to fly” and was posted eight(!) months ago...
 

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
297
Location
Downham Market, Norfolk, UK.
The other night I was watching the latest Raptor video and saw an interesting reality check, maybe for every project. The first video suggested in the side bar was another of Peter’s called something like “Ready to fly” and was posted eight(!) months ago...
Like yourself I often go back months or even years and it always just 'ready to fly' I'm sure that in his mind Justin and Elliot will arrive at 10am, have a brew, and by 11am will be flying circuit and bumps, by 3pm say yes that's nice, now fly off the other 36 hours, and wait for the hundreds of orders to flood in !!!
In the real world I see the redrive shredding the belts before the runway ends and I pray there's enough runway to brake/land/stop !!!! :-(
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,584
Location
Port Townsend WA
The VK-30 had a Continental IO-550-G - it wasn't an auto conversion. Did have a long prop shaft, though.
Wiki is incorrect, I think. My memory was the prototype was a V-8 auto engine conversion. (will check archives later)
I saw the prototype Oshkosh static display in 1987. The finish was flawless.
They quickly evolved to conventional from the early mistakes of the radical prototype.
 
Last edited:

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,584
Location
Port Townsend WA
Way OT, but this:


from "Flying" magazine indicates that there was ONE VK-30 that was outfitted with a V-8 non-auto conversion, and that there were plans for turbines.
I don't think it's off topic. It shows how the company evolved. That non-auto engine was 1992. I still think the 1987 prototype was a car engine. But can't enter EAA archive now, site is down.
 
Last edited:

autoreply

Well-Known Member
Joined
Jul 7, 2009
Messages
10,753
Location
Rotterdam, Netherlands
If you assign material properties to each part, then yes - it can give you a weight roll-up for parts, sub-assemblies and overall assemblies. With composites, it's harder to be accurate, as wet layups can vary substantially in thickness and resin content, and even with prepregs, it's harder than with metals. Also, adhesive bonding is never as accurate as one assumes for bond-line thicknesses, and then you've got poorly controlled squeeze-out amounts, so there's a built-in error there, and it's never in the right direction. But you CAN get close.
We're typically within 4% for prepregs and a tad over that for infusion. Usually similar spread for ultimate strength and stiffness even if it's buckling-driven.

But that is the result of a decade of designing, building and testing. Impossible to pull of if you're just a SW-driver.
 

cblink.007

Well-Known Member
Joined
Jul 7, 2014
Messages
435
Location
Texas, USA
"I don't have time to do that"
Ouch.

Red flag, anyone?

In all my adventures in engineering academia, military aviation and flight test et al, I have learned one very important thing:

If you do not have the time to do it properly, all the way, do not do it.

If this dude actually said that, you absolutely did the right thing by distancing yourself. This is an aircraft; a bespoke design; an apparent attempt at reinventing the wheel, and he indicates that he doesn't have time for a detail? That, my friends, is a No-Go.

Last time I checked, no aircraft, pax or pilot are immune to rock poisoning. Taking the time to give attention to engineering, construction and maintenance details tend to be the best possible preventive vaccination against rockvirus.
 
Top