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Search: Posts Made By: photofly
Showing results 1 to 35 of 47
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Forum: Private Flying
23rd Jun 2021, 14:53
Replies: 31
Views: 5,035
Posted By photofly

Right. Airplanes have forward motion, and can use...

Right. Airplanes have forward motion, and can use passive surfaces to react the torque. But it’s also interesting to note that airplanes are inherently roll stiff in a way helicopters aren’t (yaw...
Forum: Private Flying
22nd Jun 2021, 11:37
Replies: 31
Views: 5,035
Posted By photofly

That's very true, but it doesn't help us...

That's very true, but it doesn't help us understand why a 120HP R22 needs an active anti-torque device that requires a gearbox, driveshaft and blades with pitch control, but a high performance...
Forum: Private Flying
19th Jun 2021, 17:43
Replies: 31
Views: 5,035
Posted By photofly

Fixed wing aircraft do have anti-torque devices....

Fixed wing aircraft do have anti-torque devices. They're called wings. If the aircraft starts to rotate in roll the different changes in angle of attack of the two wings (one will increase, the other...
Forum: Private Flying
19th Oct 2018, 02:18
Replies: 1
Views: 786
Posted By photofly

Empty of weight of a Grob 115C

Can anyone help me out by posting the empty weight of a GROB 115C of their recent acquaintance? I've got my eye on one to buy, but its useful load seems much reduced from what it should be, for no...
Forum: Flight Testing
2nd Mar 2013, 02:06
Replies: 58
Views: 26,315
Posted By photofly

You haven't touched the pitch trim, so the...

You haven't touched the pitch trim, so the trimmed AoA stays the same.
If the aircraft is in a turn then:

a. it's not accelerating downwards. It's descending, but at a constant rate, to first...
Forum: Flight Testing
1st Mar 2013, 23:50
Replies: 58
Views: 26,315
Posted By photofly

An airplane is trimmed to fly at a particular...

An airplane is trimmed to fly at a particular angle of attack, hands off; that's an inherent feature of the pitch stability mechanism.

If you don't apply back pressure then the AoA won't change,...
Forum: Tech Log
5th Feb 2013, 17:54
Replies: 17
Views: 11,175
Posted By photofly

There's a very detailed study of engine-out...

There's a very detailed study of engine-out flying, here, which might be useful:
Multi-Engine Flying [Ch. 17 of See How It Flies] (http://www.av8n.com/how/htm/multi.html)
Forum: Private Flying
31st Jan 2013, 18:06
Replies: 77
Views: 13,314
Posted By photofly

That's a strong assertion, for which no evidence...

That's a strong assertion, for which no evidence at all is offered, and one I don't believe is correct.

It's also false on the plain English meaning of the relevant regulations. If leaving the...
Forum: Private Flying
31st Jan 2013, 12:24
Replies: 77
Views: 13,314
Posted By photofly

Canadian regulations use the same terminology...

Canadian regulations use the same terminology ("flight time" - means the time from the moment an aircraft first moves under its own power for the purpose of taking off until the moment it comes to...
Forum: Private Flying
31st Jan 2013, 04:39
Replies: 25
Views: 14,049
Posted By photofly

Moment of inertia scales with distance squared;...

Moment of inertia scales with distance squared; rolling torque scales as the distance. That suggests that with equal aileron area an aircraft with two short wings will roll faster than an aircraft...
Forum: Questions
19th Dec 2012, 11:03
Replies: 9
Views: 3,954
Posted By photofly

There's a very good and clear discussion of AC...

There's a very good and clear discussion of AC and longitudinal stability beginning on p 47 of this book, Aerodynamics For Naval Aviators:
...
Forum: Questions
13th Dec 2012, 12:02
Replies: 9
Views: 3,954
Posted By photofly

Each airfoil has its own aerodynamic centre. When...

Each airfoil has its own aerodynamic centre. When you have a wing and a tailplane you have a single "aerodynamic system". Just like you define the AC of a wing as the point about which the pitching...
Forum: Questions
13th Dec 2012, 04:54
Replies: 9
Views: 3,954
Posted By photofly

I was reading up on this today, so I'll have a...

I was reading up on this today, so I'll have a stab at trying to explain what I've learned.

The aerodynamic centre of an airfoil (or an aircraft) is a useful concept when considering its pitch...
Forum: Tech Log
3rd Dec 2012, 14:06
Replies: 388
Views: 99,876
Posted By photofly

Well, of course. Two dimensional wings are always...

Well, of course. Two dimensional wings are always in ground effect, because they have the flow pattern of a three dimensional wing with infinite wingspan. Not co-incidentally, they also generate lift...
Forum: Tech Log
3rd Dec 2012, 13:01
Replies: 28
Views: 6,673
Posted By photofly

That was when lecturers were sufficiently...

That was when lecturers were sufficiently unsophisticated in their understanding of physics to be unable correctly to perform an analysis of forces in a rotating frame. Thankfully things have...
Forum: Tech Log
3rd Dec 2012, 12:57
Replies: 388
Views: 99,876
Posted By photofly

Those are unhelpful, and incorrect diagrams. They...

Those are unhelpful, and incorrect diagrams. They give the impression that ground effect is something to do with the height of the wing from the ground being related to the chord, which it isn't....
Forum: Tech Log
26th Jun 2011, 02:11
Replies: 41
Views: 18,003
Posted By photofly

If you stick to standard rate turns, you're not...

If you stick to standard rate turns, you're not bothered about the angle of bank.

The radius turns out to be V(kts)/187, in nm - which is pretty close to 0.5% of your speed. Make appropriate...
Forum: Tech Log
24th Jun 2011, 02:44
Replies: 26
Views: 18,667
Posted By photofly

Except in so far as saying "controls to the...

Except in so far as saying "controls to the maximum inputs" - it's only one control.
Forum: Tech Log
21st Jun 2011, 10:26
Replies: 26
Views: 18,667
Posted By photofly

That's FAR part 23 - airworthiness standards. ...

That's FAR part 23 - airworthiness standards.

I think you're confusing the definition of Va with methods of determining its value.
Forum: Tech Log
20th Jun 2011, 19:37
Replies: 26
Views: 18,667
Posted By photofly

There are different ways to define Va, but that...

There are different ways to define Va, but that doesn't mean they're all correct.

See Maneuvering Speed Limitation Statement...
Forum: Tech Log
20th Jun 2011, 18:09
Replies: 26
Views: 18,667
Posted By photofly

I don't think that's exactly right. I think it's...

I don't think that's exactly right. I think it's the max speed at which the sudden and full deflection of any *single* control is sure not to cause structural damage.

I believe in pratical...
Forum: Tech Log
20th Jun 2011, 03:23
Replies: 26
Views: 18,667
Posted By photofly

There are different limits. g load limits are...

There are different limits. g load limits are related to (eg) the weight the wings and load-bearing structure can definitely support, in a downward direction. Vne is related to the force of the air...
Forum: Tech Log
16th Jun 2011, 01:54
Replies: 8
Views: 10,016
Posted By photofly

Re 10% of airspeed+7: It may be accurate...

Re 10% of airspeed+7:

It may be accurate enough, but it's still not very accurate, particularly at low speed. The correct expression should, I think, be arctan(v/364), where v is the speed in...
Forum: Tech Log
7th Jun 2011, 23:02
Replies: 29
Views: 6,231
Posted By photofly

Which was the point I was making...

Which was the point I was making...
Forum: Tech Log
7th Jun 2011, 12:55
Replies: 29
Views: 6,231
Posted By photofly

Um... how do these sensors work then?

Um... how do these sensors work then?
Forum: Tech Log
7th Jun 2011, 11:40
Replies: 29
Views: 6,231
Posted By photofly

@Damien1989, Tell (remind) your father that...

@Damien1989,

Tell (remind) your father that the pitot tube doesn't - and isn't there to - measure airspeed. It's there to measure the dynamic pressure, (1/2.rho.v^2) which governs the aerodynamic...
Forum: Tech Log
22nd May 2011, 00:48
Replies: 16
Views: 2,885
Posted By photofly

Define the "overall system" and perhaps that will...

Define the "overall system" and perhaps that will help...
Forum: Tech Log
20th May 2011, 12:32
Replies: 21
Views: 4,817
Posted By photofly

Indeed. Which is exactly what I meant by my...

Indeed.

Which is exactly what I meant by my next sentence "Although depending on how far aft of limit the CofG was, the aircraft might have been loaded *not* to maintain a given angle of attack."...
Forum: Tech Log
20th May 2011, 03:39
Replies: 21
Views: 4,817
Posted By photofly

Basic theory suggests that since the trim of an...

Basic theory suggests that since the trim of an aircraft (whatever it be) is to fly a particular angle of attack, reducing thrust (and therefore speed) would have brought the nose down. Although...
Forum: Tech Log
18th May 2011, 21:02
Replies: 26
Views: 15,899
Posted By photofly

I think it does. Maybe I should get one...

I think it does.

Maybe I should get one source of confusion out of the way, by saying the "zero" angle of attack is the angle of the airfoil that generates no lift. In that it differs from any...
Forum: Tech Log
18th May 2011, 18:37
Replies: 26
Views: 15,899
Posted By photofly

That can't work. The only way it can work is for...

That can't work. The only way it can work is for the wing at the back to have a higher angle of attack than the wing at the front".

Example: if the pitch of the aircraft increases by 2 degrees,...
Forum: Tech Log
4th May 2011, 03:08
Replies: 75
Views: 43,714
Posted By photofly

From the Wikipedia page on the Griffon engine: ...

From the Wikipedia page on the Griffon engine:
"Pilots who transitioned from the Merlin to the Griffon engine Spitfires soon discovered that, because the Griffon engine's propeller rotated in the...
Forum: Tech Log
7th Apr 2011, 11:04
Replies: 105
Views: 38,461
Posted By photofly

I got that - I was wondering about the argument...

I got that - I was wondering about the argument over descents over POM. That makes no sense to me, and I was wondering if I was missing something that might be helpful.

aterpster: question about...
Forum: Tech Log
7th Apr 2011, 09:38
Replies: 105
Views: 38,461
Posted By photofly

Much as I'm enjoying this thread, somewhere along...

Much as I'm enjoying this thread, somewhere along the way I've lost track of what the protagonists actually disagree about. Could someone fill me in please?
Forum: Tech Log
6th Apr 2011, 13:57
Replies: 105
Views: 38,461
Posted By photofly

Aterpster, just for clarity: in regular holds one...

Aterpster, just for clarity: in regular holds one adjusts the outbound time to make the inbound leg one minute (or 1.5 minutes) - is it a deliberate difference to make the outbound leg 1 minute for a...
Showing results 1 to 35 of 47
 
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