vertical grimmace

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Ramm, prop on landing issues are generally associated with too much pitch. Even though the engine is at idle, the prop still creates thrust. So a lower pitch is going to give you more of a "braking" action. This especially shows up when you are flying an airplane that is very clean aerodynamically, which the D9 is. Hence the need to use flap properly. More pitch will give more thrust than less, if the rpms at idle are the same. THis will hold true at idle, in the air as well. An extreme example of this is in pylon racing. Trying to land one of those at idle is very tough, so we just deadsticked them in, so we could get a good approach and get them to stop.

There was a lot of discussion earlier in this thread about some having problems not having any luck landing this plane. The times I witnessed such issues, the plane was not slow enough, and a high pitched prop was being used.

zrooster

I can see how my comments came off as working backward from a prop, but not my intention at all. My point was simply that I've still got an open mind WRT motor, so final prop size will be TBD. That said, I do have my heart set on a three blade. All you say concerning not being able to see a prop in flight is true, but everyone has their hangups, and props are one of mine. I was almost willing to go with a 2 blader until I saw the 3 blade on dgiatr's plane. If the XYZ can swing one of the ones you described and make reasonable power, I'll probably go with that combination. The eme was just tempting due to the electric starter...my knees and shoulder are already worn out from flipping props! I'll probably compromise and get an external electric starter. Thanks again for the SA!

vertical grimmace

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If you really want to spin a more scale sized prop, then a reduction drive is in order, and would get you close. The problem is you do not have the room for it if you care about keeping the engine hidden, mostly. Which I assume would be important as well considering the desire for the scale prop.

One of my biggest problems with a scale 3 blader would be the cost. I honestly break too many props to justify the cost. It bothers me enough breaking the $25 ones!

http://www.vogelsang-aeroscale.com/g...eschlundt.html

Ramstein44

My Feedback: (157)

Something I agree on...Dang Vertical, don't tempt the man with something he cant use...

zrooster

I hear you! I've gotten pretty confident as I haven't had a prop strike in over a year, so the cost isn't scaring me right now, but I've probably just jinxed myself!

And, yes, keeping it mostly hidden is very important to me!

vertical grimmace

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Just trying to provide info on what it would actually take to achieve the goal! There is a reason why you never really see a scale sized/looking prop on the WW2 stuff. They are just not really practical in our size.

zrooster

Roger, depends on what compromises you're willing to make. I'll do some ground testing and if I can satisfy myself then GTG, if not I'll go with the two blader. Obviously, there'll be some additional cost associated, but it's worth it to me.

Katniss

Pretty hard to claim the ones Vertical has seen having difficulty landing, that were using a high pitch prop, had much to do with idle speed. The reason being, those with high pitch props would more then likely be using an electric motor and as such, there is NO idle speed. Throttle to zero means the prop is just freewheeling due to the oncoming air and therefore is providing no thrust.
But....small amount of throttle(such as mimicking a fuel based motor at idle,but an electric with high pitch prop) to maintain forward motion to attempt to prevent a bounce, yes, it makes it slightly more difficult to slow down and the plane wants to float on by.
A larger plane using a radial motor generally also uses a high pitch prop due to low rpm output by the motor. Usually those...such as using a moki 200-250 are using a 16 pitch prop. It just takes practice on the specific plane to get dialed in to how it will react, and basing a statement on limited exposure to seeing a specific plane landing with whatever gear it has been outfitted with, well...it take more then 2 flights for someone to make an ACCURATE judgment on whats going on when they are not the one flying the planes themselves.

zrooster

There is a point at which, regardless of pitch, a prop is producing (for all intents and purposes) zero thrust, even if it's still being driven by the motor. For those familiar with the basics of flight aerodynamics there are four basic forces that effect an aircraft....thrust, drag, weight and lift. In straight and level unaccelerated flight, drag works in direct opposition to thrust... (and increases exponentially with speed). So, though a prop is producing some thrust, there is a point at which it is not sufficient to overcome the drag produced by the airframe and that produced by lift. In fact the prop itself, at low RPM, will produce more drag than thrust. You have to be able to get the power back though, and it may require a carb adjustment if the motor is idling too high. There is another factor (really there are many other factors). In a descent, the weight component can be broken up into two vectors, one of which will work in concert with thrust and could cause the plane to accelerate. No revelation, I know (a plane will tend to accelerate in a dive), but the point is, how steep was the approach? Longer shallower approaches may produce better results.

Edited to add...as we're all aware, a prop blade is just an air foil. The lower the RPM, the less the air flow over it...there is an RPM above zero at which there is insufficient airflow over the blade for it to produce any thrust, even high pitch blades (it will just occur at a lower RPM).

Many on here probably already know all this, and I apologize if I insulted anyone's intelligence.

vertical grimmace

My Feedback: (1)

Your right, your poor landings had nothing to do with the prop, it was all in a bad approach. Yours is not the only one I have seen fly, just so you know. But then again, you will continue to blame the long landing gear for your inability to stall a wing properly, but that is another discussion.

Katniss

I don't know why you continue to like to insult me....I don't understand what pleasure you get from this. The landings were not as poor as youre trying to state and UNTIL you actually fly one of these planes..a D9 with correct landing gear)....you have no room to speak. I was not mentioning anything about length of gear in my post or what all the factors were....electric motor/high pitch prop/light wingloading/long landing gear/etc etc etc. The very first flight, yes, I bounced it....so what?? Had half flaps.....determined needed full flaps to add drag. New plane....floats like a kite...didn't get it slow enough. 2nd flight...better.....didn't bounce as bad....you see?? It's called LEARNING your plane. Third flight(after minor repairs)....Perfect landing!
4th flight..... let you egg me into landing it from a direction I'm not used to. Nailed the touchdown.... but it did veer off the edge of the runway tearing out the gear. Why you feel the need to harp on me is beyond comprehension.
I was being rather nice and just stating it may take a few flights for someone(including me) to get used to how a specific plane behaves. I'm apparently not perfect....no kidding.... I am human. Stop bothering me

vertical grimmace

My Feedback: (1)

Who insulted who? If you do not like the downward path of our conversations, then do not lead them in that direction.

Ramstein44

My Feedback: (157)

Vertical, I think you should just buy my ESM D 9 and fly it, that way you'd have some personal experience with this plane to support your theories on it.

zrooster

In my experience, it is unnecessary and indeed (in many cases) inadvisable to fully stall an aircraft on landing. Closest I think I've ever come was a blip of stall horn just before touchdown, but that typically comes on around 1.3 Vs. Furthermore, excessive speed is not what causes an aircraft to bounce on landing. 100% of bounced landings are caused by an excessive rate of descent (VVI/VSI) on touchdown. This can be brought about by either a failure to flare, an incomplete flare, or getting too slow at too great a height and dropping it in. The only time I've ever seen excessive speed associated with a bounce is if an individual either touches down at too great a VVI or attempts an abrupt flare to save it...the latter is more of a balloon than a bounce. In either case adding a touch of power and then letting it settle can smooth it out, or simply go around and try again.

Situations where you would want to definitely carry a little extra speed include ~high winds, cross winds or gusty winds. When in doubt, speed is your friend in most situations. In fact, though the WWII vets who originally flew the planes insist a 3 point is the only way to go, they were extremely proficient at the time which is what is required to 3 point those high performance aircraft safely. MOST folks (unless they're Bob Hoover) who fly full scale warbirds today will wheel them on because it's the safer thing to do (a good demonstration of why that is can be found in a fairly recent P51 crash at Oshkosh...individual had it slowed sufficiently to execute a 3 point, but when he tried to execute a go around he torque rolled and crashed...slower aircraft = more susceptible to torque roll). Same reason one might want to wheel on their scale warbird that they've got a couple grand and many hours invested in...at least until they become more proficient and are ready for a new challenge!

vertical grimmace

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I'll trade you back the Holman kit?! lol

vertical grimmace

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I'll trade you back the Holman kit?! lol

vertical grimmace

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In my experience, model aircraft that bounce and do not land properly are because they are carrying too much energy, generally because they are not even close to the stall speed at touchdown. You do not have to be fully stalled at touchdown, but you need to be fairly close. The maneuver that is the landing, is a controlled stall. There are great writings on this topic, that relate to full scale in the book "Stick and Rudder".

Most modelers are scared to get their aircraft down to the proper landing speed. This takes practice and lots of touch and goes. I do not have to have flown this exact airplane to know what is wrong with the landings I see. I have flown plenty of different designs for 30 years to know how to properly land a particular type. The FW 190 D is actually one of the easier ones, and that is why lately in this thread you are seeing many comments on how good it is at landing.

zrooster

A landing is not a controlled stall. It's a controlled descent into touchdown. You should really never stall the wing on a landing or it'll drop in on you. I'm a retired military and now commercial professional pilot who teaches people how to fly fullscale on the side for fun (including taildraggers). I've been flying most of my life. It's my profession. It's what I do.

vertical grimmace

My Feedback: (1)

Sweet. Good for you. I am not the one having problems with my landings. As much as full scale relates to model flight, it is an entirely different beast. No benefit of instruments. If your wing never stalls after touchdown, you would continue flying, one of the primary causes of these modelers bouncing, and becoming airborne again, then slapping down, and tearing out their landing gear. Seen it too many times.

zrooster

Incorrect. How do you define a stall?

vertical grimmace

My Feedback: (1)

Not enough airflow over the airfoil to generate enough lift. to overcome the weight of the given aircraft. The point at which flow separation exists in front of the center of pressure.

You would be the first pilot I have ever met that will not acknowledge that the stall is part of the landing. I question your experience seriously. I am no novice to full scale either.

zrooster

Question away, there is no requirement to stall prior to touchdown. In fact it's inadvisable. Your comprehension of applied aerodynamics is severely lacking. You almost got it with the flow separation, but insufficient lift to overcome weight = descent. You can counter this by increasing AOA, but eventually you reach that AOA at which the wing stalls...the critical AOA. If you reached critical AOA prior to touchdown, the airplane will drop out of the sky. I'm guessing you might have a PPL at most, and I'd be shocked if you have over 300hr. You make cabinets, I fly airplanes. Recommend you stick to your area of expertise. You're giving bad advise and it's going to cost someone their airplane, if it hasn't already.

BTW, credentials in the form of my license with ATP rating and Retiree ID card available via PM to a third party upon request.

vertical grimmace

My Feedback: (1)

I have never once said to stall the wing in flight, before touchdown. That is you inaccurate assessment of what I said.

Like I said, I am not the one having a problem with my landings. And full scale only partially relates to landing a model aircraft. I have no questions for you. You are the one asking them of me.

I have a long list of aircraft designs that have proven themselves in competition. I have had no issues with my understanding of aerodynamics as far as model aircraft go. Which is what we are talking about.

zrooster

I may have misunderstood what it is that you were getting at initially, and if so, I apologize for that. BL, I feel that the information I passed here is sound and applies to both full scale and model aircraft, but folks can take it FWIW. Anyway, I'm here to revel in one of my all time favorite aircraft with like minded people and learn as much as possible about building a nice ARF (freely admit building is my weak point). To everyone, sorry to distract from the primary thrust of this thread.

On a sad note, I was just notified by Tomas at VQ that boxes were mislabeled and that the D9 is in fact temporarily out of stock. So, I'll have to wait at least another month...been drooling over this thing for nearly two years and just when I was ready to pull the trigger everyone is out!

vertical grimmace

My Feedback: (1)

I apologize for the distraction as well.

I was wondering about VQ and who the importer for ESM would be. It was my understanding that Troy built brought them in, but were no longer going to. If you notice on their website they are out of stock on almost all of them.

The FW 190 D9 is a nice model as ESM stuff goes. As I airbrushed the mottling on Katniss's a couple of years ago. The retract mounts may need to be strengthened, unless you can grease your landings every time. If ESM is lost, not sure how an airplane like this can be had without building one.