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Author Topic: The importance of slow flying speed in UK scale competition  (Read 1574 times)
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Jack Plane
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« Reply #25 on: October 15, 2016, 03:52:50 PM »

Russ

Post it as often as you like Grin its a lovely video of a lovely model!

I'm rather falling for the little Piet with its oversize wheels...
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Jack Plane
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« Reply #26 on: October 15, 2016, 04:00:20 PM »

A very good point, thanks Ricky.  A short nose without a car engine and 3/4 of the rubber aft the CG would equal a fair wadge of additional nose-weight.

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daveh
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« Reply #27 on: October 15, 2016, 05:07:59 PM »

A thought occurs that if a model is produced with a fixed undercarriage of an aircraft that has/had a retractable undercarriage, cruising speed doesn't enter into it as generally the maximum speed allowable with the gear down is well below the 'cruising' speed. It should also be remembered that there is actually no such thing as 'cruising' speed for a full size aircraft but rather range speed (i.e. the speed for a certain weight, configuration [and wind to be pedantic] that will give the greatest range) or endurance speed (i.e. the speed for a certain weight and configuration that will give the greatest endurance). This, of course, ignores combat, or manoeuvre, speed. Hence there will theoretically be a range speed and an endurance speed for a situation where for some reason the gear is stuck down. Soooo... it all depends on how the model depicts the real aircraft - does it aim to show a fixed undercarriage type climbing out and after some time at range speed returning to land or, at the other end of the spectrum, a retractable undercarriage type that for some reason is not going to raise its gear but after a short flight merely land without reconfiguring? In between, of course, there are many other combinations. Maybe the entrant's documentation should state what sort of flight is going to be represented with the relevant speeds stated on which the judges can base their marks?

This really is a fascinating topic.

Dave   
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Russ Lister
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« Reply #28 on: October 15, 2016, 05:26:31 PM »

Just in case I consider building one ... what was the takeoff speed of a Hunter, Dave?  Roll Eyes
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Pete Fardell
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« Reply #29 on: October 15, 2016, 05:32:13 PM »

Maybe the entrant's documentation should state what sort of flight is going to be represented...
You mean something like, "My model's flight will represent the aircraft as being flown by an incompetent student pilot doing his first solo who drastically over-throttles, loses control, stalls, panics and crashes into a wall."

Worth a go I suppose.
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« Reply #30 on: October 15, 2016, 05:40:56 PM »

Pete ... you'll be sat in the corner!
Wouldn't do any harm ... provided the information was true of course. Might even make the judge's work easier if they have not got to assess it themselves as much?
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daveh
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« Reply #31 on: October 15, 2016, 05:44:42 PM »

Just in case I consider building one ... what was the takeoff speed of a Hunter, Dave?  Roll Eyes

Typically 150 knots; max speed with gear down 250 knots; endurance speed about 180 knots; typical touchdown 135-140 knots. So, at 1/20th scale between 6.75 and 12.5 knots - make sure you have the flaps at about 38o though....

Let me know when it's ready for trimming flights  Grin

Dave
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Russ Lister
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« Reply #32 on: October 15, 2016, 06:03:48 PM »

Thanks Dave .... fast, but not quite as fast as I expected actually. But I still won't put it on the list!

I remember considering a B26 Marauder until I read about the landing speed (90 knots)... wouldn't necessarily translate to a model, but I turned the page!

It will be fascinating to see what evolves to make best use of the Walsall venue and the 200g limit ... I suppose one of the only ways to improve on a performance like Mike's Moth is a multi-engine model flying just as well?

This might be limited by access to suitable trimming halls. This year I slightly damaged the SE5a at Bushfield and then flew it at the Harvey Hadden centre.
The hall there is made slightly narrower than it could be by a dividing wall so I made the turn tighter ... looked OK there, but not so good at Walsall. (first time for me with a full house of qualifying flights though)


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SP250
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« Reply #33 on: October 15, 2016, 08:50:30 PM »

Slight problem with putting all this speed info and flight profile detail into the static judging information.
The flying judges won't see it.

My tuppence at 1.50 am after a long day at a BMFA STC meeting.

John
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DavidJP
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« Reply #34 on: October 16, 2016, 05:08:53 AM »

Thanks Russ - always a pleasure to watch!
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John Webster
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« Reply #35 on: October 16, 2016, 06:10:09 AM »

If I may stick my colonial foot into a discussion peculiar to the mother country;

Way back in 1973 I worked for Grumman-American Aviation, builders of two and four place aluminum single and twin engined airplanes. When a new airplane was being designed the engine weight and load (persons, luggage and fuel) and the guesstimated airframe weight would be added together. Then an airfoil would be chosen and the wing area and aspect ratio would be juggled to provide a suitable stalling speed. Then a cruise speed would be guesstimated and the wing incidence would be determined based on the low point of the airfoil's drag bucket while carrying the airframe weight plus passengers and luggage and 1/2 fuel plus 45 minutes emergency fuel (usually 2 or 3 º).

Free flight models fly just above stalling speed. The initial power burst from the rubber motor results in a climb because any speed above the trimmed speed produces lift. As the power declines the nose angle declines but the speed remains the same because the difference in the incidence of the wing and the elevator is set during the trimming process to produce a speed just above the stall speed.

Flying speed could be reduced by increasing the difference in the angle of attack of the wing and the elevator but increased nose weight would be required which would increase the stalling speed slightly.

Flying speed could be increased by building heavy. I'm an expert at that.

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Pete Fardell
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« Reply #36 on: October 16, 2016, 07:16:19 AM »

I've now found my dad's published views on scale flying speed as applied to large RC models. Not as extensive a discussion as I remembered and not in RCM&E either, but from a series he did on building scale biplanes in the now defunct RC Model FLYER magazine in 2009. Not sure how relevant this is to indoor scale freeflight, but anyway...
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Re: The importance of slow flying speed in UK scale competition
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« Reply #37 on: October 05, 2018, 06:34:20 AM »

I'm prompted to post on this thread again after seeing Mike Stuart's Fox Moth on the BMFA facebook page this morning.

I was going to put the comment 'game changer' .... Mike and Monz were early movers into the bigger and slower flying models at Walsall as we know.
Then I remembered Jon's Camel! I wouldn't say that it bucks the trend entirely, but it is a refreshing answer to the question posed in this thread.
So, both big and small are still capable of winning (at Walsall in particular)
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billdennis747
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« Reply #38 on: October 05, 2018, 08:02:05 AM »

For me, the 'early mover' into slow and realistic flying was Mike Hetherington's Stosser in the late 70s. Things then swung to heavier, faster and more detailed models and are only now coming back. How  a model scores on flying depends largely on how well the judges are clued in to speed realism, both indoors and out. It is not uncommon to see 9s and 10s given but this is rarely merited if speed is properly-assessed; exceptions including the models of Mike and Monz and a very few others. I think there is a tendency on the part of judges (indoor and out) to see flights as 'good for a free flight model', whereas it should be being judged against perfection.
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« Reply #39 on: October 05, 2018, 08:15:33 AM »

Yes .... I apologise Bill .... I've not been around that long!
This thread does have a Nottingham to walsall emphasis that perhaps I forgot to mention!
Having said that, I do remember Mike.
I might be wrong, but I think one of the most evocative aeromodelling photos that I have seen involved the Hetheringtons?
Was it Mike raising an encouraging fist as one of his models rolled out to ROG?
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« Reply #40 on: October 05, 2018, 08:17:38 AM »

..... I think the photo was in the Aeromodeller in the AMI era?
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Prosper
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« Reply #41 on: October 11, 2018, 04:43:42 AM »

I'm pleased to see that your father gave prominence to the psychological elements in his article Pete, and not just the numbers (as in performing a calculation and declaring 'this is the scale speed'). When we see A380s or what have you late in their approach, everyone from non-aviation people to pilots will see something flying unbelievably slowly (how does it stay up?). If the next 'plane in that same piece of sky was a midget racer at the same speed, ≈ 140kt, it would appear to be going at the helluva clip. I think the background, and the distance of the model from the background, is important too though p'raps not so much as the model's distance from the observer as your father says. This may sound odd but I believe that the amount your head and/or eyes have to move to track a model are also significant - I think that along with other things, the brain computes this in its estimations of speed.

Next 'plane in the sky: an Optical Ilyushin.

Stephen.
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« Reply #42 on: October 11, 2018, 05:35:54 AM »

Next 'plane in the sky: an Optical Ilyushin.

I see what you did there.

Returning to the way we see models in indoor FF competition, it;s a good point that cruising, combat and aerobatics are not particularly relevant. What we mainly of both the models, and as personal witnesses to full size aviation, is take-off, initial climb, final approach and landing. and the comment about Hunter flaps is well made. If I ever get round to my Lysander project I'll do that with flappery and slattery rather than a clean wing (then you can all enjoy the folly)
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Snaky Stringer
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« Reply #43 on: October 11, 2018, 06:17:06 AM »

I think I may have to revive my notion of doing a modified Comet Corsair with flaps and gear down. Should be fun.
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« Reply #44 on: October 11, 2018, 10:59:32 AM »

Yes, that would be interesting to try. Other WW2 scale types on which a judicious amount of flap deployment might help, rather than hinder, include the Fairey Firefly and Barracuda. I would definitely not try it with e split-flap type like a Spitfire or Hurricane. With them the flap is mostly drag and very little CL boost.
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Pete Fardell
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« Reply #45 on: October 11, 2018, 11:31:28 AM »

Yes, that must be the danger of adding flaps and suchlike; if they don't work like the real thing then it's just more weight and drag = more power required = flying faster than ever.

I put slats (though not flaps) on my Storch. They didn't seem to slow it down at all, but did perhaps draw extra attention to the fact that it wasn't flying as slowly as it should have been!
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« Reply #46 on: October 11, 2018, 12:26:23 PM »

The key to flying slowly is to build light.  Check out Mike Kirda's indoor Taylorcraft.  He posted a nice YouTube video link the other day.

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=23666.msg232169#msg232169

If a Herr Helio Courier could be put on a similar diet, it might just create the realistic impression of "STOL" flight, without flappery and slattery. (I liked that phrase,WIP)

Mind your airfoil camber!
« Last Edit: October 11, 2018, 12:46:53 PM by Indoorflyer » Logged

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« Reply #47 on: October 11, 2018, 12:47:44 PM »

Yes, the Taylorcraft looks superb!  Smiley
I hope Mike is not planning a visit to the UK next spring! Tongue
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Russ Lister
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« Reply #48 on: October 11, 2018, 12:52:49 PM »

I have to be honest .. I don't think I've ever seen a better kit scale flight!
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