Will this thing fly? Bonkers AeroD.

What your instructor never taught you. Continuing your education and learning from others. Flight safety topics and accident/incident discussions.

Moderator: Moderators

Rotorblade
Priming
Posts: 35
Joined: Wed Sep 25, 2013 12:12 pm
Closest Airfield: Stellenbosch
Location: Cape Town
Has liked: 4 times
Been liked: 13 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by Rotorblade » Thu Oct 15, 2020 11:10 am

Uncle Jim,

Otherway around-

When you open a warm oven, the heated air moves from your oven into the atmosphere. Outwards.

Fridge: it is atmosphere moving into fridge.

So, you can use the oven to heat the room but not the fridge to cool te room.

At this time however, nothing is sure anymore :D
User avatar
StressMerchant
1k poster
1k poster
Posts: 1424
Joined: Mon Jul 03, 2006 8:57 am
Closest Airfield: Cab
Location: The Matrix
Has liked: 43 times
Been liked: 145 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by StressMerchant » Thu Oct 15, 2020 11:12 am

A little knowledge can be a dangerous thing ;-)

Going back to high school maths:
  • Assume that we have two variables a and b, and that: a = b
  • Multiply both sides by a to get: a^2 = ab
  • Subtract b^2 from both sides to get: a^2 - b^2 = ab - b^2
  • This is the tricky part: Factor the left side (using FOIL from algebra) to get (a + b)(a - b) and factor out b from the right side to get b(a - b). If you're not sure how FOIL or factoring works, don't worry—you can check that this all works by multiplying everything out to see that it matches. The end result is that our equation has become: (a + b)(a - b) = b(a - b)
  • Since (a - b) appears on both sides, we can cancel it to get: a + b = b
  • Since a = b (that's the assumption we started with), we can substitute b in for a to get: b + b = b
  • Combining the two terms on the left gives us: 2b = b
  • Since b appears on both sides, we can divide through by b to get: 2 = 1
Simple proof that 1=2 and therefore space-time is not merely curved, but completely bent?

Following on from that, it's easy to show that wind tunnels can be lift devices, that Bladerunner can levitate himself on his rope, and time for traverse will be zero. ;-)

Sometimes the tricky questions are the ones that test our true understanding
These users liked the author StressMerchant for the post:
jimdavis
The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair.
- Douglas Adams
Rotorblade
Priming
Posts: 35
Joined: Wed Sep 25, 2013 12:12 pm
Closest Airfield: Stellenbosch
Location: Cape Town
Has liked: 4 times
Been liked: 13 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by Rotorblade » Thu Oct 15, 2020 11:25 am

Exactly!

This is what I found: learn the books, memorise, and you will ace the exam. Dig deeper for true understanding to test if what I am reading is true and makes sense under different scenarious and things sometimes becomes lekker fuzzy.

Sequential thinking (with little and limited knowledge or not seeing the system as a whole) brought me to weird outcomes. Your gut feel tells you that someting is off and here is the value of the Academy. It truly teaches what instructors could not.

Love them all but sometimes one gets stumped but is afraid to ask as not to look like a noodle.

Thank you for your explanation. Things are clearer now. Sincerely appreciated.

At least this is not a perpetual motion machine for it is going nowhere.
Rotorblade
Priming
Posts: 35
Joined: Wed Sep 25, 2013 12:12 pm
Closest Airfield: Stellenbosch
Location: Cape Town
Has liked: 4 times
Been liked: 13 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by Rotorblade » Thu Oct 15, 2020 11:35 am

Curious question on windtunnels:

I now fully accept that the foil is not producing nett thrust and no relative motion. And the building is not going to fly away anytime.

When the lift generating capacity of the foil is determined in a windtunnel, it is a situation where the tensile force in the constraining strut is measured and then expressed as magnitude of lift?

Had a look if I could find the answer and seemingly there is some measuring device used to determine the magnitude of lift but details are scarce.

Again, respect for the Wright brothers and all other pioneers are going through the roof. To do what they have done from very little is simply mind blowing
User avatar
StressMerchant
1k poster
1k poster
Posts: 1424
Joined: Mon Jul 03, 2006 8:57 am
Closest Airfield: Cab
Location: The Matrix
Has liked: 43 times
Been liked: 145 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by StressMerchant » Thu Oct 15, 2020 12:09 pm

At university we measured loads using a load cell arrangement. At one of my jobs where we had a very nice windtunnel, the loads were measured using a balancing lever arrangement, where weights were moved along threaded balance levers until equilibrium was achieved.

Doing the measurement is fairly complex because you have to determine forces and moments, and there are sometimes unwanted effects from the one to the other. You end up with a matrix of "influence co-efficients" that needs to be applied to the raw results. One of my classmates spent his summer vacation calibrating one of the measurement "balances", was not a one-day job.
The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair.
- Douglas Adams
Rotorblade
Priming
Posts: 35
Joined: Wed Sep 25, 2013 12:12 pm
Closest Airfield: Stellenbosch
Location: Cape Town
Has liked: 4 times
Been liked: 13 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by Rotorblade » Thu Oct 15, 2020 6:52 pm

Thank you for the response! Fascinating stuff!

Thank you
User avatar
Orthin Opter
Frequent AvComer
Posts: 959
Joined: Wed May 18, 2011 4:35 pm
Closest Airfield: Tranquility
Location: Back of the moon
Has liked: 50 times
Been liked: 64 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by Orthin Opter » Thu Oct 15, 2020 7:09 pm

Rotorblade wrote:
Thu Oct 15, 2020 9:58 am
Wind is moving air. When I open my fridge the warmer ambient air in the kitchen displaces the colder air when the door is opened. Because I am facing the fridge, the air is moving from behind me to my front. Thus, I feel a wind on my back. Buys-Ballot says the low is on my right...
EISH. The perceptions of the inquisitive mind... The cold air in the fridge is more dense, so it moves down and cools your feet, The displaced air is replaced by warmer ambient air. (The ambient air does not force its way into the fridge.) So you have a tailwind at your back and a headwind at your feet.
And the question was??? I forget...
OH yes. Just remembered: You cannot lift yourself up by your boot straps / laces / skipping rope. Sir Isaac (as Uncle Jim said) proclaimed in law #3 that for each action, there is an equal and opposite reaction.
"All great truths begin as blasphemies." George Bernard Shaw.

"The main vice of capitalism is the uneven distribution of prosperity.
The main vice of socialism is the even distribution of misery." Winston Churchill.
Airwayfreak
1k poster
1k poster
Posts: 1531
Joined: Mon Oct 19, 2015 9:56 am
Closest Airfield: FAJS
Location: Johannesburg
Has liked: 34 times
Been liked: 163 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by Airwayfreak » Fri Oct 16, 2020 12:09 pm

StressMerchant wrote:
Thu Oct 15, 2020 11:12 am
A little knowledge can be a dangerous thing ;-)

Going back to high school maths:
  • Assume that we have two variables a and b, and that: a = b
  • Multiply both sides by a to get: a^2 = ab
  • Subtract b^2 from both sides to get: a^2 - b^2 = ab - b^2
  • This is the tricky part: Factor the left side (using FOIL from algebra) to get (a + b)(a - b) and factor out b from the right side to get b(a - b). If you're not sure how FOIL or factoring works, don't worry—you can check that this all works by multiplying everything out to see that it matches. The end result is that our equation has become: (a + b)(a - b) = b(a - b)
  • Since (a - b) appears on both sides, we can cancel it to get: a + b = b
  • Since a = b (that's the assumption we started with), we can substitute b in for a to get: b + b = b
  • Combining the two terms on the left gives us: 2b = b
  • Since b appears on both sides, we can divide through by b to get: 2 = 1
Simple proof that 1=2 and therefore space-time is not merely curved, but completely bent?

Following on from that, it's easy to show that wind tunnels can be lift devices, that Bladerunner can levitate himself on his rope, and time for traverse will be zero. ;-)

Sometimes the tricky questions are the ones that test our true understanding
Sorry. Your logic is flawed as follows :

You say : Since (a - b) appears on both sides, we can cancel it to get: a + b = b

You also state a=b. So therefore (a - b) = 0

You are therefore saying you should divide by 0 which is not a legitimate mathematical argument. Sorry :lol: :lol:
These users liked the author Airwayfreak for the post:
jimdavis
User avatar
StressMerchant
1k poster
1k poster
Posts: 1424
Joined: Mon Jul 03, 2006 8:57 am
Closest Airfield: Cab
Location: The Matrix
Has liked: 43 times
Been liked: 145 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by StressMerchant » Fri Oct 16, 2020 12:29 pm

You are therefore saying you should divide by 0 which is not a legitimate mathematical argument. Sorry
Damn, you spotted it ;-)
These users liked the author StressMerchant for the post:
jimdavis
The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair.
- Douglas Adams
User avatar
rare bird
Too Tousand
Too Tousand
Posts: 2665
Joined: Sat Jul 31, 2010 2:47 pm
Has liked: 654 times
Been liked: 213 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by rare bird » Sat Oct 17, 2020 9:50 am

I did some experiments quite a while ago by blowing denser air (Argon and CO2) and less dense air (Helium) over model wing profiles to see the effects of density. My original idea was to have a cylinder of CO2 or Argon in the aircraft and actually blow it over the wing surface while landing, to try to lower the stall speed (similar to the Buccaneer that used to blow bleed air over the wing for BLC (Boundary Layer Control)).
What I actually ended up discovering was that viscosity also plays a role - more significantly than what I initially thought it would.
You do not have the required permissions to view the files attached to this post.
These users liked the author rare bird for the post (total 2):
jimdavisRotorblade
User avatar
jimdavis
10000 and still climbing
10000 and still climbing
Posts: 16779
Joined: Thu Jun 19, 2008 7:46 am
Closest Airfield: FAGG
Location: Wilderness
Has liked: 842 times
Been liked: 1024 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by jimdavis » Sat Oct 17, 2020 10:24 am

rare bird wrote:
Sat Oct 17, 2020 9:50 am
I did some experiments quite a while ago by blowing denser air (Argon and CO2) and less dense air (Helium) over model wing profiles to see the effects of density. My original idea was to have a cylinder of CO2 or Argon in the aircraft and actually blow it over the wing surface while landing, to try to lower the stall speed (similar to the Buccaneer that used to blow bleed air over the wing for BLC (Boundary Layer Control)).
What I actually ended up discovering was that viscosity also plays a role - more significantly than what I initially thought it would.
ЭТО ВЫГЛЯДИТ КАК ЗАГРУЗКА ЛОШАДЕЙ

jim
These users liked the author jimdavis for the post:
rare bird
"PPL Manual"
"Flight Tests"
"So Others May Live"
"Flying in Africa" Vol 1
"Flying in Africa" Vol 2
Look inside these books, or buy them at: www.jimdavis.co.za.
User avatar
rare bird
Too Tousand
Too Tousand
Posts: 2665
Joined: Sat Jul 31, 2010 2:47 pm
Has liked: 654 times
Been liked: 213 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by rare bird » Sat Oct 17, 2020 10:31 am

while it is good for the brain to think about the limits of our flying machines and to dream of other possibilities, in my observation it boils down to 1. money and 2. support & what is readily available off the shelf and 3. safety.
1. For the expense of needing a runway, using a wing profile to give lift is way cheaper than most other methods I have seen to defy gravity.
2. to fly all by yourself is not as fun as to fly with others - so having the same technology gives a basis for helping each other, and far easier to buy off-the shelf readily available products.
3. proven safety issues / history (we don't have time to make all the mistakes ourselves)

for the same money as developing a new concept, I personally would rather have something simpler that works, e.g. a speed brake (like on a glider or small business jet) to help give extra control with the transition period when lift stops working as I slow down and land on the RWY. just my own opinion.
User avatar
StressMerchant
1k poster
1k poster
Posts: 1424
Joined: Mon Jul 03, 2006 8:57 am
Closest Airfield: Cab
Location: The Matrix
Has liked: 43 times
Been liked: 145 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by StressMerchant » Sat Oct 17, 2020 10:39 am

jimdavis wrote:
Sat Oct 17, 2020 10:24 am
ЭТО ВЫГЛЯДИТ КАК ЗАГРУЗКА ЛОШАДЕЙ
jim
I don't know, it's all Greek to me ;-)
These users liked the author StressMerchant for the post:
jimdavis
The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair.
- Douglas Adams
User avatar
jimdavis
10000 and still climbing
10000 and still climbing
Posts: 16779
Joined: Thu Jun 19, 2008 7:46 am
Closest Airfield: FAGG
Location: Wilderness
Has liked: 842 times
Been liked: 1024 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by jimdavis » Sat Oct 17, 2020 5:58 pm

StressMerchant wrote:
Sat Oct 17, 2020 10:39 am
jimdavis wrote:
Sat Oct 17, 2020 10:24 am
ЭТО ВЫГЛЯДИТ КАК ЗАГРУЗКА ЛОШАДЕЙ
jim
I don't know, it's all Greek to me ;-)
Thanks stressors, and I thought it was Rusky language. :lol:

jim
"PPL Manual"
"Flight Tests"
"So Others May Live"
"Flying in Africa" Vol 1
"Flying in Africa" Vol 2
Look inside these books, or buy them at: www.jimdavis.co.za.
User avatar
rare bird
Too Tousand
Too Tousand
Posts: 2665
Joined: Sat Jul 31, 2010 2:47 pm
Has liked: 654 times
Been liked: 213 times

Re: Will this thing fly? Bonkers AeroD.

Unread post by rare bird » Sat Oct 17, 2020 8:40 pm

jimdavis wrote:
Sat Oct 17, 2020 5:58 pm
StressMerchant wrote:
Sat Oct 17, 2020 10:39 am
jimdavis wrote:
Sat Oct 17, 2020 10:24 am
ЭТО ВЫГЛЯДИТ КАК ЗАГРУЗКА ЛОШАДЕЙ
jim
I don't know, it's all Greek to me ;-)
Thanks stressors, and I thought it was Rusky language. :lol:

jim
what Jim wrote is Russian - something about a horse / gallant steed (or was it just horseplay?)
You do not have the required permissions to view the files attached to this post.

Return to “Academy & Flight Safety”