News Flash!!! A 6 Pound Glider Caught A Thermal June 21

[flystoolow]

Just Unbelievable, Congratulations To The Winning Aero-science Team.

[histarter]

You ought to organinize a fraturnity for heavyweights. We could call it the Fat Frat! :eek:

[little flyer]

ahh... do you know how much full scale ships weigh? or even 1/4th scale?

[Ollie]

What is the story? What is the wing area? What's fly too low into a thermal? Please be specific. ;)

[Hostage-46]

ahh... do you know how much full scale ships weigh? or even 1/4th scale?

Hmm lets see the Glasflugel 304C, my dream ship of choice, has a gross weight of 992 lbs. That's about right for a modern single seat glider. With an L/D beyond 40/1, it will outperform all of our toys with ease.

Have a look...

Glasflugel 304C is now prepared for
production by HPH Ltd.

TECHNICAL DATA
Wings
Span 15,00 m
Wing area 9,90 m2
Aspect ratio 22,80
Wing airfoil HQ 014-1642
Fuselage
Length 6,45 m
Height 1,36 m
Weight
Empty weight 235 kg
Max. take off weight 450 kg
Water ballast capacity 115 l
Min. wingloading 30,80 kg/m2
Max. wingloading 45,45 kg/m2
Performance
Best gliding ratio (expected , not measured yet )
at 450 kg and 116 km/h L/D 42,5
Minimum sink rate
at 305 kg and 77 km/h 0,57 m/s
Speeds
Minimum speed
at 305 kg 60 km/h
at 450 kg 73 km/h
Maximum speed 250 km/h
Note: this data is not binding, for information

So what is the big deal anyway?

[cmhshh]

So what is the big deal anyway?
Someones discovered hot air rises by the sound of it :confused: :confused: :rolleyes: ;)
SH

[histarter]

Aquariums and fish are like soaring things. The bigger the tank, the bigger the fish! Seems reasonable to me. :confused:

How about Cheap cross country travel with a 707 size sailplane that uses the thermal heat of cities to keep it up. :cool: Re should be high enough to push L/D over 125! With weight and profile to keep airspeed at less than 140 mph, it would sink about the same as our models! ;) For making up lost time? The passangers can all move forward to get the machine on step! Darn it, I just blew another April 1st article! :eek:

[flystoolow]

April 1st?

Careful there histarter; we've all been reading your daily advise, and no one thought you were joking. :)

I do have a serious question for you though, it pertains to your specialty field, 'Spiral diameter'.

Q - If a Cessna 172 is flying up a narrowing valley beneath solid cloud cover and eventually has to make an emergency turn (ie. valley is very narrow), what does the pilot have to do to decrease the 'spiral diameter' to the bare minimum to avoid colliding with the opposite mountain side?

[GoFaster]

Q - If a Cessna 172 is flying up a narrowing valley beneath solid cloud cover and eventually has to make an emergency turn (ie. valley is very narrow), what does the pilot have to do to decrease the 'spiral diameter' to the bare minimum to avoid colliding with the opposite mountain side?

Crank up motor RPM? You know, that noisy thing at the front. :p

[DFW_HLG_TG]

Q - If a Cessna 172 is flying up a narrowing valley beneath solid cloud cover and eventually has to make an emergency turn (ie. valley is very narrow), what does the pilot have to do to decrease the 'spiral diameter' to the bare minimum to avoid colliding with the opposite mountain side?



This ought to be good.

[Hostage-46]

This ought to be good.
Oh ya

[histarter]

BA=(V^2/rg) Tan-1 [g=9.81 mtrs/sec/sec, r= radius in mtrs, V= mtrs per sec]

Airspeed is the problem #1

Close throttle, drop flap to about 30 degrees. When arispeed is below 65 start turn and add power to maintain airspeed above 60 in tight turn - to prevent stall-in-turn. Without cloud cover, stall turn would be first choice (even though a friend of mine died pulling off that manuever with a Super Cub at Boliver Texas).

I owned a 172 ragwing about 15 years ago. Aluminum landing gear was as springy as a buckboard! Stability, compared to a Tcraft, was great for flying turn about a point! True love was a Stinson Voyager.

[flystoolow]

Very good, my apologies for making light of your area of expertise, the 'Spiral diameter'. You pass with a solid 'A'.

You're a good sport, Histarter; I'll have to stop giving you such a hard time! :)

Flystoolow

[DFW_HLG_TG]

Agreed, very good answer.

[Hostage-46]

Hmmm we lost a crew to a mountain pass .... those who get into that situation don't generally seem to have the sense to get out of that mess.

I personally couldn't get myself to pull power ... unless I was already in the clouds and in deep kimshee...

[histarter]

Flying full size safely is sort of mundane. FAA frowns on stunting, in fact spin education is now replaced by spin avoidance. If one is never allowed to Immelman, one gains no expertese in the manuever, and thus attempting to do so in the real world is very dangerous!

I believe that most commercial pilots (airline primary) have lost the art of flight, and fly by the number! My instructor broke me of that habit by putting a cardboard shield over my instrument panel, and had me shoot oodles of touch and goes. I think FAA should require a commercial pilot to perform about 8 hrs per year in a light plane VFR, or fly a low powered model airplane* for equal time, to reinforce the mechanics of flight.

*Telemaster Senior with OS 25 swinging a 11X3 prop. :) Laugh if you want, but it is a great training aid! Level airspeed clean is very close to a 40! Preset takeoff and landing trim works just like full size.

[FWFlyer]

BA=(V^2/rg) Tan-1 [g=9.81 mtrs/sec/sec, r= radius in mtrs, V= mtrs per sec]

Airspeed is the problem #1

Close throttle, drop flap to about 30 degrees. When arispeed is below 65 start turn and add power to maintain airspeed above 60 in tight turn - to prevent stall-in-turn.We are trying to minimize Radius.
Look at the numbers here (http://142.26.194.131/aerodynamics1/Lift/Min_Radius.html)

The number 1 problem is to increase bank angle.

[histarter]

FW

If you will look at the math, and crunch the numbers into the formulah, you will see that the 172 is banked at 30 degrees! Going for more bank is unsafe for a very small gain in radius! More airspeed has a squared effect and Diameter is aready about 1000 feet, so what will 100 feet or so less get you? If you permit yourself to be trapped for a close tolorance turn, your bold enough to go accrobatic! Natures way of sorting out bold from old! :eek:

Doing it my way with the stall horns ringing in your ears, while your mind is over-ruling them, is all the stunting I want to do! :p

[FWFlyer]

Q - If a Cessna 172 is flying up a narrowing valley beneath solid cloud cover and eventually has to make an emergency turn (ie. valley is very narrow), what does the pilot have to do to decrease the 'spiral diameter' to the bare minimum to avoid colliding with the opposite mountain side?
Histarter,
I am answering the problem as defined in the stated question. If you want to rewrite the problem to suit your wishes, go ahead.

[histarter]

FW

I really don't know what your problem is. Full flap, 60 degree bank @ V above 80 (if possible including a spiral decent) and diameter will still be almost the same - but at conciderably higher risk? Diameter is controlled by airspeed Squared, and that is prime. ;)

The more bank the more airspeed needed to hold the machine in the air and large flap angles eat up power to fly faster. If you wish to live life with an Oweja Board, and feel safe by imagination, take my Chart from GA, and cycle programs in 1/2 degree steps to find the absolute minimum numbers (time consuming and would be quite difficult to maintain in the real world).

At that point in time it would be smarter to just Immelman out because before you could crunch the exact numbers....smunch!

Now please give me the answer on how to increase BA without increasing airspeed and/or the diameter, other than you and your passenger bailing out -to reduce the weight and lower stall speed? :p

[FWFlyer]

I really don't know what your problem is. First, let me apologize for being so blunt. I was out of line when I first posted my reply. But I will say that the "problem" as you say that I have is called accuracy. I believe that giving the correct answer to a question is important.

Now please give me the answer on how to increase BA without increasing airspeed... Nowhere have I said that you can increase BA without increasing speed. The page I pointed to in my earlier post clearly shows that you must increase speed with increased BA.

Re-read the page in the link. The numbers are there: Increased speed + Increased bank angle produced a SMALLER TURN RADIUS.
The facts about increased g's are there. Safety issues are addressed on the page. I also never said that the smallest radius was safer. I said it was smaller. That is the correct answer to the question asked. Can you agree that the crunched numbers, when plugged into the formula that you provided, produce the answer to the original question? If you can't agree to the results using your own formula, this discussion is over.

[histarter]

75 degree bank angle = 120 mph must fly for maintenance of 3.7 G; and turning diameter is about 38% smaller theoretically! :eek:

1. This is a stunt because I don't believe the 172 can hold the airspeed with the amount of power it has available - and I wouldn't like to try it, unless not in a mountain pass with tapering walls - as the question was phrased.

2. If I had that kind of power, I believe I still would prefer the Immelman over the high banked turn. Less stress all around (i.e. if I had the opertunity to practice with it to begin with). :o

3. Piloting and stunt flying really calls for different kinds of pilots. I can honestly state that I am not qualified to do both. And the 172 is not accrobatic material.

My big stunts were landing and taking off my 1500 ft runway, spins and recovery, getting a Republic Seabee off a 3000 ft runway on a really hot day, and night flying without lights (I missed a destination):rolleyes:

[histarter]

Hats off, You win! :)

I have to agree with you FW. I guess I flew a bit too much text book. I did have fun when I did what felt right - like tight box for final and sidesliip for glide control on top of flaps. ;)

The turn discussed is only a 180, and there is enough inertia for follow through without a lot of airspeed bleed off. I just don't like Gs!

Come to think of it, most of the machines I flew were weak on aileron, and it was difficult to get them past 45 degrees in a bank. The Cessna was more active. :confused:

I had a partner that flew with me occassionally (who flew Ag Cat crop dusters) and he also though I was too prissy! I always wished I could man handle a machine like Doyle (banging into the stops), but it never rubbed off.

[barefootbass]

I learned in my dad's 46 t-craft. Stall spins, flying with that wonderful wing talking too you right at stall speed for as long as you could hold it. That bird would wingover like nobody's buisness, my move of choice, and not nearly as much g force involved.

[histarter]

I learned in my dad's 46 t-craft. Stall spins, flying with that wonderful wing talking too you right at stall speed for as long as you could hold it. That bird would wingover like nobody's buisness, my move of choice, and not nearly as much g force involved.

To roll up a wing to vertical on a 41 Tcraft (that has weak ailerons to begin with) one would have to exceed Vne (another limit that I tended to avoid with ancient aircraft). On my old rebuilt Tcraft the limit was 104 mph. The cruise prop would take me to 103, so I would have to dive to get the extra 25 mph...
No thank you.

Tcraft soft stall was amazing. Doyle once came up almost 20 feet high on a landing - and sink was going up when the wheels hit the ground hard. Next weekend Doyle replaced the bungee shocks.

My Tcraft investigated oil fields in Midland, service work for Hinkley & McCoy's isolated cherry pickers etc. It worked rather than played! :(

[histarter]

Talked to 2 other pilots with 172 experience. Both agreed that bank and pile on the Gs would not work very well! And is dangerous because true bank angle tends to be overestamated and difficult to select w/o lots of practice - "I looked out the window and the wings were vertical in the turn - Gs? nothing noticable." Obviously is a false statement.

[One pilot described the detail of doing wing overs with airspeed above Vne. A high risk manuever for me!] :eek:

[barefootbass]

We never even approached the VNE (120 on a BC12D) just pull up at around 90 knts, rudder, counter aileron, then pull out. never went over 100 and at no altitude loss either. I don't think it was a "true" wingover as the wing never did make vertical but that's what we called it none the less. In all reality it was probably closer to a half spin rotation move but above stall speed. Actually closer to an Immellman but without as much vertical climb. Is a "wingover" a bank and yank manuver? If so than my terminology is wrong. :confused:

[Hostage-46]

Wingovers and barrel rolls are 1 G manuevers...

[barefootbass]

Okay, so what am I talking about? A low angle Immelman?