24 Apr 2024, 07:21 [ UTC - 5; DST ]
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 20:26 |
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Joined: 10/06/19 Posts: 139 Post Likes: +45 Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: This is good. Can you distill it down to the top 3 issues/risks? Help us man. You are obviously bright.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 20:30 |
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Joined: 10/06/19 Posts: 139 Post Likes: +45 Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: If it bounces during taxi, I would be EXTREMELY worried about flutter at TAS well below 300 knots. Does he have an airframe parachute (and a prop brake) installed for the test flights? Is it flutter or just a rough runway? Coming around to your way of thinking.... maybe.... but let us keep it constructive... solution bias as the "end result?" Folks that matter... i.e. you old fellas... weigh in?
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 21:27 |
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Joined: 05/01/14 Posts: 8803 Post Likes: +13586 Location: Операционный офис КГБ
Aircraft: TU-104
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Username Protected wrote: If it bounces during taxi, I would be EXTREMELY worried about flutter at TAS well below 300 knots. Does he have an airframe parachute (and a prop brake) installed for the test flights? Is it flutter or just a rough runway? Coming around to your way of thinking.... maybe.... but let us keep it constructive... solution bias as the "end result?" Folks that matter... i.e. you old fellas... weigh in?
On the ground it is not flutter, at least not aeroelastic flutter. The question you mean to ask is is it bouncing because the control system has play or because the controls are moving due to rough pavement. I won’t bother to guess an answer to that, but the other posts on the topic seem to indicate there is more than a tiny amount of play.
Aeroelastic flutter is an aerodynamic oscillation that can rip off wings or even collapse bridges. See the Tacoma Narrows Bridge for perhaps the most famous example of the latter. In aircraft it is a complex issue, but flex or play in control surfaces and increasing TAS are very big risk factors.
There are plenty of videos online, but this quick one from NASA should make it clear why it is so dangerous.
https://youtu.be/OhwLojNerMU
_________________ Be kinder than I am. It’s a low bar. Flight suits = superior knowledge
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 21:28 |
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Joined: 03/15/16 Posts: 450 Post Likes: +346 Location: NC
Aircraft: Looking for one
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Username Protected wrote: This is something that bothers the crap out of me. Like literally would not get in the plane.
So maybe the question that arises is, given the vast damn knowledge in this forum, is would we as a community let this guy crater it in (if we are right) or will we pull together and get our voices heard in a reasonable way? Maybe even give the fella a deserved(?) helping hand?
Just cause he is trying don't mean he is perfect.
Guy is obviously smart and is obviously tired.
Are we excused then from helping?
If you read through all of the thread over on the homebuilt site, you will see that several of the guys comment on the videos and try to voice concerns. If I remember correctly from that thread, several of the experts that have helped Peter all voiced concerns over different things and he kind of discounted them. I know it seems that people are rooting against him. But, I think most of the people in the E-AB community are really open minded people that will do whatever they can to help each other.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 21:37 |
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Joined: 05/17/10 Posts: 4434 Post Likes: +1739 Location: canuck
Aircraft: x23mouse
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Username Protected wrote: If you read through all of the thread over on the homebuilt site, you will see that several of the guys comment on the videos and try to voice concerns. If I remember correctly from that thread, several of the experts that have helped Peter all voiced concerns over different things and he kind of discounted them. just started to have a look myself & that jumps out right away, seems totally blasé about a redrive not even sorted on the ground yet, gotta wonder whoall is involved in decision making
_________________ nightwatch...
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 21:46 |
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Joined: 05/01/14 Posts: 8803 Post Likes: +13586 Location: Операционный офис КГБ
Aircraft: TU-104
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Username Protected wrote: This is good. Can you distill it down to the top 3 issues/risks? Help us man. You are obviously bright.
No need for three. If the ailerons have play, the #1 issue is aeroelastic flutter and the #1 risk is the wings ripping off. I can’t put odds on flutter occurring because it is complex, but if it does occur, the odds of catastrophic structural failure are very high.
The Velocity team was concerned enough to redesign their control system as part of an effort to reach Lancair IV speeds and they didn’t have a lot of play to begin with. The Raptor is aiming to go even faster.
_________________ Be kinder than I am. It’s a low bar. Flight suits = superior knowledge
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 21:47 |
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Joined: 10/06/19 Posts: 139 Post Likes: +45 Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: If you read through all of the thread over on the homebuilt site, you will see that several of the guys comment on the videos and try to voice concerns. If I remember correctly from that thread, several of the experts that have helped Peter all voiced concerns over different things and he kind of discounted them. just started to have a look myself & that jumps out right away, seems totally blasé about a redrive not even sorted on the ground yet, gotta wonder whoall is involved in decision making
This is a fine comment... and true.. But as a community let us keep it positive.
I submit the guy is brilliant but tired.
Let's help not hinder?
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 22:25 |
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Joined: 04/06/11 Posts: 7955 Post Likes: +3996
Aircraft: Warbirds
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Username Protected wrote: just started to have a look myself & that jumps out right away,
seems totally blasé about a redrive not even sorted on the ground yet,
gotta wonder whoall is involved in decision making This is a fine comment... and true.. But as a community let us keep it positive. I submit the guy is brilliant but tired. Let's help not hinder? I know a couple that needed more hinderance. Or at least listening to some knowleable people and They might still be alive. 40s, 50s and 60s pushing to a new frontier in Avaition filled many gravesites. Those ideas typically had enough might and need behind them that a new airframe and pilot were sitting in the shadows to fly over the still smoking hole. I fear the endeavors that seem to roll on past a stopping point just because of inertia.
_________________ Be careful what you ask for, your mechanic wants to sleep at night.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 22:34 |
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Joined: 10/06/19 Posts: 139 Post Likes: +45 Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: This is a fine comment... and true.. But as a community let us keep it positive.
I submit the guy is brilliant but tired.
Let's help not hinder?
I know a couple that needed more hinderance. Or at least listening to some knowleable people and They might still be alive. 40s, 50s and 60s pushing to a new frontier in Avaition filled many gravesites. Those ideas typically had enough might and need behind them that a new airframe and pilot were sitting in the shadows to fly over the still smoking hole. I fear the endeavors that seem to roll on past a stopping point just because of inertia.
Myself brother. Buried a few. And that not be the worst? Built a ramp for a fella who would be forever a paraplegic. Still alive sucking dinner out of a straw. <-- Wheelchair access only.
Get your fear. So lean in in the right direction in a constructive way?
Last edited on 03 Nov 2019, 22:40, edited 1 time in total.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 22:37 |
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Joined: 10/06/19 Posts: 139 Post Likes: +45 Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: Summary:
It won’t make design goals because it’s overweight. Even being polar.
The re-drive skipping teeth is a bad sign for powerplant longevity.
The aileron slop is potentially dangerous. Brilliant analysis. 1,2,3, 1.) If it makes it within 75% of goal is that worthy? (Yes!!!!) 2.) Correct. Will it kill someone? Maybe but not initially probably. Later problem to solve. 3.) Yes for sure!! First problem for the group to attack and solve?
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 22:58 |
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Joined: 02/28/17 Posts: 1214 Post Likes: +1191 Location: Panama City, FL
Aircraft: Velocity XL-RG
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Username Protected wrote: Thank you!! How much load do you put on the surface (weight wise) to get that deflection? Have you measured (or can you as an example) what the deflection is with flight loads? And can someone here tell us what that is? 10lbs? 50lbs? I have no idea. Well.. I have an idea... but no practical knowledge. Anyone? Bueller? About 20lbs.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 23:11 |
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Joined: 05/01/14 Posts: 8803 Post Likes: +13586 Location: Операционный офис КГБ
Aircraft: TU-104
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Username Protected wrote: 1.) If it makes it within 75% of goal is that worthy? (Yes!!!!)
Not sure I can agree. 225 knots on 20 gph would not be all that special for an experimental, and not worth the safety risks associated with the high landing speeds and the unknowns and untesteds in this design vs established tried and true competition. Within 90% becomes interesting.
_________________ Be kinder than I am. It’s a low bar. Flight suits = superior knowledge
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 23:18 |
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Joined: 05/17/10 Posts: 4434 Post Likes: +1739 Location: canuck
Aircraft: x23mouse
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Username Protected wrote: 1.) If it makes it within 75% of goal is that worthy? (Yes!!!!)
flight testing is next on the agenda, nothing else matters yes & why? or pause, think it over & delay
_________________ nightwatch...
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 03 Nov 2019, 23:24 |
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Joined: 10/06/19 Posts: 139 Post Likes: +45 Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: 1.) If it makes it within 75% of goal is that worthy? (Yes!!!!)
flight testing is next on the agenda, nothing else matters yes & why? or pause, think it over & delay
If the ailerons are a screwed as we think may be possible.. gonna be a short flight...
We need to get to the bottom of this problem?
https://www.youtube.com/watch?v=NT_3HUp3ZlU
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