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Search: Posts Made By: oggers
Showing results 1 to 35 of 41
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Forum: Tech Log
24th Jun 2012, 13:59
Replies: 156
Views: 91,284
Posted By oggers

Keith that's the second time you've scurried off....

Keith that's the second time you've scurried off. However, since your last reappearance you have spouted plenty of waffle in my direction [including explicitly "inviting" me to comment]. So whether...
Forum: Tech Log
24th Jun 2012, 11:54
Replies: 156
Views: 91,284
Posted By oggers

Keith Williams: Actually it doesn’t...

Keith Williams:



Actually it doesn’t imply that. From the essay again:



…which is a basic tenet of the fluid dynamics here. Vi is half ΔV. Those for whom this is not ‘pretty well known’...
Forum: Tech Log
22nd Jun 2012, 11:56
Replies: 156
Views: 91,284
Posted By oggers

Keith: Yeah, but irrelevent....

Keith:



Yeah, but irrelevent. :rolleyes:



..and they all imagine their thrust in terms of a man rowing a boat down a canal a la your little analogy? :ok:
Forum: Tech Log
21st Jun 2012, 10:49
Replies: 156
Views: 91,284
Posted By oggers

Keith, that is a big strawman, and not your...

Keith, that is a big strawman, and not your first. Nobody has said that entering auto is a simple matter of throttling back the throttle := What I wrote was that your description of what constitutes...
Forum: Tech Log
15th Jun 2012, 16:58
Replies: 156
Views: 91,284
Posted By oggers

keith Williams: . <<Thrust Horsepower:...

keith Williams:

.

<<Thrust Horsepower: The amount of horsepower the engine-propeller combination transforms into thrust.>> McGraw-Hill Dictionary of Aviation

Zero thrust horsepower ≡ zero...
Forum: Tech Log
16th Apr 2012, 19:04
Replies: 156
Views: 91,284
Posted By oggers

Keith Williams and barit1: You...

Keith Williams and barit1:





You say THP is thrust x velocity. I agree. But I say that only works for a specific set of assumptions. Static thrust is not the only scenario that doesn’t...
Forum: Tech Log
13th Apr 2012, 14:51
Replies: 156
Views: 91,284
Posted By oggers

Keith: Just to be clear in case I left...

Keith:



Just to be clear in case I left you in any doubt whatsoever. Yes I DO believe that if thrust is not zero then propeller efficiency is not zero. Thanks for clarifying that you don't...
Forum: Tech Log
13th Apr 2012, 13:08
Replies: 156
Views: 91,284
Posted By oggers

That's an odd thing to say barit1. I'm...

That's an odd thing to say barit1. I'm interested, has anybody on this thread suggested such a thing or did the idea arise in your own domain?



Sorry, is that propeller efficiency = zero? I...
Forum: Tech Log
13th Apr 2012, 12:30
Replies: 156
Views: 91,284
Posted By oggers

Keith Williams.... Any THP? ...

Keith Williams....



Any THP?

....any thrust horsepower or not? Propwash wasted? And propeller efficiency - more than zero or not? Same questions to barit1.

[BTW haven't forgotten to...
Forum: Tech Log
12th Apr 2012, 15:57
Replies: 156
Views: 91,284
Posted By oggers

keith, don't worry. I'm reading your last three...

keith, don't worry. I'm reading your last three posts very carefully, and I can see a couple or three things that deserve a considered response :ok:

[edit: it may take til after the weekend though]
Forum: Tech Log
12th Apr 2012, 14:32
Replies: 156
Views: 91,284
Posted By oggers

Okay barit1. I can see you don't want to answer...

Okay barit1. I can see you don't want to answer the question. THP is the unit of measurement for power available. I think that is about as close to standard use of terminology as one is going get in...
Forum: Tech Log
12th Apr 2012, 11:21
Replies: 156
Views: 91,284
Posted By oggers

Interesting post Keith. I will give it my full...

Interesting post Keith. I will give it my full consideration. For now I'll just point out that I most certainly haven't overlooked the propwash, having specifically referred to it as being the place...
Forum: Tech Log
12th Apr 2012, 07:59
Replies: 156
Views: 91,284
Posted By oggers

barit1 "Propulsive work". Clearly,...

barit1



"Propulsive work". Clearly, everyone can see that.

But the question I asked of you was: is THP the measure of power available from the prop or not? Because when I said it was, you...
Forum: Tech Log
11th Apr 2012, 14:09
Replies: 156
Views: 91,284
Posted By oggers

barit I said 'THP is the power available'....

barit

I said 'THP is the power available'. It wasn't meant as a definitive definition of THP, merely an attempt to use some words to give context to the paragraph.





Now, are you trying...
Forum: Tech Log
11th Apr 2012, 11:17
Replies: 156
Views: 91,284
Posted By oggers

Sure, no power is required if the aircraft is at...

Sure, no power is required if the aircraft is at standstill but that does not mean no power is available. OTOH power is required to accelerate the mass of the vehicle from standstill with or without...
Forum: Tech Log
6th Apr 2012, 09:54
Replies: 156
Views: 91,284
Posted By oggers

RRT, Thanks that's a nice clear reference. ...

RRT,

Thanks that's a nice clear reference.

Pi = T x Vi

THP = T x V

The principle of THP extended to the hover. No need for the aircraft to move.
Forum: Tech Log
5th Apr 2012, 17:07
Replies: 156
Views: 91,284
Posted By oggers

Keith, I'm not interested in your purpose for...

Keith, I'm not interested in your purpose for contributing. You did contribute.

If you believe that propeller efficiency cannot be other than zero when the aircraft is stationary just ask yourself...
Forum: Tech Log
5th Apr 2012, 12:45
Replies: 156
Views: 91,284
Posted By oggers

Keith, all reasonable contributions are welcome. ...

Keith, all reasonable contributions are welcome.

The assumption is we have thrust:



I disagree with your conclusion. For a helo in the hover propulsive efficiency is zero. But “the power...
Forum: Tech Log
3rd Apr 2012, 12:11
Replies: 156
Views: 91,284
Posted By oggers

Blackhand: rolling road dyno - good example....

Blackhand: rolling road dyno - good example. Makes the point clearly.
Forum: Tech Log
2nd Apr 2012, 19:20
Replies: 156
Views: 91,284
Posted By oggers

I squeeze it in between the pilates and AA...

I squeeze it in between the pilates and AA meetings.
Forum: Tech Log
2nd Apr 2012, 13:54
Replies: 156
Views: 91,284
Posted By oggers

Capt Pit Bull: The issue I’m disputing is...

Capt Pit Bull:

The issue I’m disputing is the assertion by italia458 (note, he raised it, not me) that a plane at standstill can knock out 200 BHP and generate static thrust, yet there is zero...
Forum: Tech Log
1st Apr 2012, 11:04
Replies: 156
Views: 91,284
Posted By oggers

Oh yeah nice one Pitbull. I'll chalk that up to...

Oh yeah nice one Pitbull. I'll chalk that up to being 1st Apr :ok:
Forum: Tech Log
31st Mar 2012, 16:33
Replies: 156
Views: 91,284
Posted By oggers

italia: Not changed my pov. BHP x PE =...

italia:



Not changed my pov. BHP x PE = THP. [notwithstanding Tx losses obviously]



Well, what I wrote and what you wrote underneath it aren't the same. But taking your little statement...
Forum: Tech Log
31st Mar 2012, 09:13
Replies: 156
Views: 91,284
Posted By oggers

blackhand: Gets my vote :ok:

blackhand:



Gets my vote :ok:
Forum: Tech Log
31st Mar 2012, 09:09
Replies: 156
Views: 91,284
Posted By oggers

That's right. You did make a mistake. But not...

That's right. You did make a mistake. But not just in that quote (which was actually two quotes anyway). No. You reiterated it across 4 pages:



etc etc.

Who are you trying to kid? You made...
Forum: Tech Log
30th Mar 2012, 20:29
Replies: 156
Views: 91,284
Posted By oggers

Italia: I’ve been reviewing the thread and would...

Italia: I’ve been reviewing the thread and would like to respond to some of your previous comments in light of recent developments:



I’d like to give you the benefit of the doubt but I’m afraid...
Forum: Tech Log
30th Mar 2012, 15:44
Replies: 156
Views: 91,284
Posted By oggers

I edited my last post - just so you know.

I edited my last post - just so you know.
Forum: Tech Log
30th Mar 2012, 15:28
Replies: 156
Views: 91,284
Posted By oggers

In that case I'm not sure what you think you're...

In that case I'm not sure what you think you're talking about but it certainly relates to the power induced by the rotor of a helicopter in the hover. :ugh: Induced power and THP - two names, same...
Forum: Tech Log
30th Mar 2012, 14:46
Replies: 156
Views: 91,284
Posted By oggers

italia: The power that comes from the...

italia:



The power that comes from the engine goes through the prop. Rudderrudderrat is correct about propeller efficiency not being zero. If it was zero there would be no thrust.

You can't...
Forum: Tech Log
30th Mar 2012, 10:27
Replies: 156
Views: 91,284
Posted By oggers

italia: back to the helicopter problem. 'No THP...

italia: back to the helicopter problem. 'No THP in the hover' you say. The two main arguments you have provided go like this:

'The aircraft doesn't move therefore no work is done on it therefore...
Forum: Tech Log
30th Mar 2012, 06:31
Replies: 156
Views: 91,284
Posted By oggers

It's what I live for blackhand :sad: italia:...

It's what I live for blackhand :sad:

italia:



I wouldn't mention that one around the hangar if I were you.

ft:
Forum: Tech Log
29th Mar 2012, 22:55
Replies: 156
Views: 91,284
Posted By oggers

ft There's really no need to get so upset....

ft

There's really no need to get so upset. If what you genuinely want is to engage in an 'educated discussion between professionals', then I don't understand why you didn't:

a) Address the OP
...
Forum: Tech Log
29th Mar 2012, 19:29
Replies: 156
Views: 91,284
Posted By oggers

italia: What if the helicopter was to climb...

italia:

What if the helicopter was to climb at a very small rate, say, 1 ft/min. Does this thrust without power you speak of suddenly become THP after all? Or just a tinsy winsy bit THP? What if...
Forum: Tech Log
29th Mar 2012, 11:23
Replies: 156
Views: 91,284
Posted By oggers

It's okay. I figured it out in 1981 with a little...

It's okay. I figured it out in 1981 with a little help from the grown-ups at Farnborough.



Not disagreed with a single reference you’ve given. Just pointed out they don’t support your point.
...
Forum: Tech Log
28th Mar 2012, 17:11
Replies: 156
Views: 91,284
Posted By oggers

italia: one word: hover. One question: any thrust...

italia: one word: hover. One question: any thrust horsepower or not?

I will leave the rest for another day :ok:
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