All Us intermediate pilots, Lets Share

[Konrad]

LG Stut Fairing.

[Konrad]

A bit more detail to my earlier post. Unlike our models most GA and aircraft from the golden era allow the sprung landing gear to splay outward as they compress. On our models the gear often moves fore and aft as the way to absorb the shock of landings. So if the LG strut fairing is attached to the strut on our models the fairing will move aft as a strut moves. This forces the fairing into the fuse ether breaking the fuse or the fairing. The trick is to make scale LG move like the full size, or allow the LG strut to move aft without carrying the fairing. Some folks have had good luck making a pocket in the fuse to receive the aft part of the aft moving fairing.

All the best,
Konrad

[Grossman56]

So, we have had 100 mph + winds here in windy Wyoming. A Port a Potty did an unscheduled flight in our parking lot at work and I'm tempted to report it to the FAA as a UAV causing trouble and flying in a unsafe manner!
Do the owners of these UAV's realize that they must follow the recent FAA mandate if they wish to operate in the sky?
Have they applied for their FAA registration number and is it properly affixed to the UAV so that it can be read without the use of tools?
Are they adhering to the 400 foot ceiling limit?
Do they realize they have to be within visual distance of the pilot and FPV doesn't count??
Do they further realize that the must also have their AMA number attached, preferably to the seat...
BTW, it was proof positive that sh*t does really flow down hill!
Pretty shi**y all around though
If we had observed a flight of Port a Potties, it would have been two sh*ts to the wind.

I could go on............
Grossman56

[Grossman56]

Oh, what the heck!! One more post because this will make it 1500 posts on the forum for me:rolleyes:
Thank you thank you!
Yep, I love this forum and appreciate all who visit regularly.
I miss the guys who have faded away.
I hope they're still around and flying and visiting here even if they're not posting.

Here's to you, all my friends , who have and continue to make this Forum enjoyable for me.

Grossman56:shy::D:)

[boomer108]

Congrats GMan!

You put me to shame, but who's counting I just enjoy the forum. The winds here in Chicago were at 60 mph today same as the temperature. Crazy weather!

Roy B.

[Grossman56]

Well, yesterday was a write off as the wind was up again. The day before was gusting up to 104 mph apparently, but today the sun is out and the wind is down. Temp is about 26 F. So down right cold, but I got three flights in with Pandora Two.
The new Black and Yellow paint scheme really stands out nice. By the third flight, the wind was starting to gust again, so brought her down and called it a successful day, besides, my hands were pretty dang cold as well.
The Pandora is a great plane, but with the wind past about 15 mph, she's fighting to push against it. Makes for some fun flights to almost hover and do some vertical landings, which is cool, but I'm thinking of upgrading at least one of them with a 3536 1250kv as I already have a 50A Esc in them. Stock they have a 3536 800kv, so that should liven them up a bit. My water transfer decals didn't stick very well, one peeled off and the others are starting to let go, I'll have to rethink them the scalloping on the wings and tail look great!!

Grossman56

[OV10]

Hey Gman,
Just wanted to make a brief comment in order to save you a butt-ache on your P2 upgrade desires.
Bumping your power system from 800 to 1250 kV is a HUGE rpm jump on that 11x6x3 prop. You'll be going from 8880 to 13875 max rpm's.
Power requirements are not a linear ramp up in either motor kV nor prop diameter/pitch/blade count changes.
My quick calculations on the power demand for that proposed motor is going to require almost 4X the amp requirements over the stock setup.
You might want to recheck your numbers because that 50A ESC is not gonna handle the load my friend.
I use this FREE Static Thrust Calculator all the time. http://personal.osi.hu/fuzesisz/strc_eng/index.htm
Best regards,

[Grossman56]

thanks OV, I was basing it on the RocHobby MSX, which uses this motor with a 40A ESC and a 11x5.5 2 blade prop. Maybe I have to change the prop as well?!
I'm an absolute beginner when it comes to these calculators, could use some help!?

Grossman56

[Konrad]

OK, now with a lot of S.W.A.Ging here is what I've come up with. I assume the OEM for the motor is Sunray and looking at some motors with a sub 30mm stator and 1250 kv I find a motor with these electrical constants. kv=1250, Io=2 amp, R=20 mohms

So I find that a three bladed 11x6 will draw a little over 63 amps on 11.1V for 450 watts at the prop (the motor is about 80+% efficient at this high current draw). Pitch speed is close to 50 mph.

All vendors not just MotionRC need to publish real engineering data for the products they sell! Motor Case diameters and lengths tell us nothing! Stator lengths and diameters tell us almost next to nothing! Please give us real numbers to work with so we can find the true potential of your products without letting out the magic smoke!

Do you have ground clearance issue for needing to use a 3 bladed prop? As you might have read from me earlier that I hate more than 2 blades on a prop unless it is an EDF unit!

[Grossman56]

I've ordered some 11x5.5 two bladed props, on their way now. This will give me the same setup as the RocHobby MXS with the exception of the ESC which is a 50A instead of a 40A. Ground clearance should be fine with these as the diameter remains the same.

Grossman56

[Konrad]

As I recall you were looking for some speed to cut into the head winds you have on the 'American Desert'. Have you thought about a prop that will be more of a speed prop like a 10x7. Looking at the MXS this looks like a 3D (Hoover) type model.

[doctormike]

I fly at 7000 ft.(Santa Fe). My planes fly surprisingly well at this altitude, with stock props. More pitch certainly does help, however. I fly in Austin Tx. (about 600 ft) now and then. It's a world of difference. I also fly my stock Radian in a mountain meadow (9500 ft.). Again it flies very well there. It's amazing...the power these electrics have! Doc

[Grossman56]

As I recall you were looking for some speed to cut into the head winds you have on the 'American Desert'. Have you thought about a prop that will be more of a speed prop like a 10x7. Looking at the MXS this looks like a 3D (Hoover) type model.

No I haven't, but that's the kind of info I need, thanks Konrad, now a 10x7 gives me one inch less diameter but more pitch with less friction because less surface slicing through the wind if I'm understanding this correctly.
We're at 5000' here in Cody, which is something I forget.

Grossman56

[Konrad]

No, the parasitic (wetted area) of the prop is not the issue.

I flew and still fly a lot between 5K and 7k feet in the Denver area. As a general rule to compensate for altitude an aircraft has to fly faster or at a higher coefficient of lift (angle of attack or new airfoil). Adding pitch speed is the easiest way to get back some performance lost to altitude. This is per the lift equation. Lift increases by the square of the velocity. As you are in thinner air you actually don't need as much dynamic thrust. So it is a good idea to trade diameter for pitch at altitude. True, these are all grossly simplified answers.

[Konrad]

I have to ask if you have had a chance to play with this emulator?
http://www.castlecreations.com/suppo...alculator.html

Now I don't want you to think I'm always geeking out at the airfield. When I go flying in Denver I usually add about 1.5 to 2 inches to the pitch of the props I would use here in San Francisco (close to sea level). If and only if I'm drawing much more current than I was at sea level, or I'm cutting into the safety head room of my equipment do I drop down in DIAMETER. I like to spec my stuff for about 15% to 20% safety margin (head room). Remember that at altitude there is less air to remove heat. So a 50 amp esc at sea level really can't be thought of as a 50 amp ESC at higher altitudes. I derate power spec's about 2% for every thousand feet.

[Grossman56]

Thanks Konrad and good to know as we are at 5000 feet here and its definitely something to take into consideration, as well as temp.

Grossman56

[Konrad]

I was typing far too fast. I should say that I up the pitch for more airspeed and drop down in diameter if the added pitch causes too high a current rise.

The temp issue is a power rating issue. As there is less air to cool things these thing can reach critical temps at a lot lower power setting.

Now this is going a bit beyond the scope of the question But I like to use what are known as pressure cowls (Plenums) to slow down the cooling air allowing it to up take heat for little in the way of a drag penalty.

Sorry,
Konrad

[doctormike]

I had not thought about the cooling issue at higher altitudes. Pressure cowls... Are you talking air scoops, or something near the ESC like a baffle, or a cowling around the ESC? If I notice an ESC that gets too warm, I put a Radio Shack heat sink on it. Thanks, Doc

[Konrad]

All a pressure cowl (plenum) is, is a device that slows down the velocity of the air by expansion. You might remember in your physics class the relationship in a fluid between pressure and velocity.

Most models have enough drag producing air inlets. The issue is that this air often doesn't go were it is needed to cool. Air is much like myself "lazy" it trys to avoid work. The expansion from heat is actually deflecting the cooling air away from the heat source. Baffles and heat sinks are often a very good idea.

On a philosophical note; I tend to try to eliminate drag to gain performance. Per the lift equation thrust is trying to over come drag. I see far too many guys trying to add more and more power (thrust) when I think it would be far more profitable to reduce the drag.

In the glow engine world that high altitude cooling issue has killed many an engine when the guy tries to use nitro to make up for the lost power do to altitude density.

[Grossman56]

Hey guys and gals, well the wind finally let up here in Wyoming and it was in the 60's after work. Had some family issues to take care of, but managed to burn through four batteries worth of flight with Pandora Two. The new motor helps quite a bit, I'd recommend it to anyone wanting a bit more out of their Pandora.
I put a 3536 580kv in both mine along with the 50A ESC that I changed out last year and the stock prop, seems to really help. Anyway, it was sure nice to get back in the saddle again, perfect flights so the Winter hasn't dulled my skills!!
I'm hoping for the same weather tomorrow as I'd like to take the Apprentice out and try her with the DX6I, just to figure out what the switches will do. The flap switch is the novice/intermediate switch, but I'm not sure which is the high/low switch and , yes, I have the receiver switch set so that those are the two options. That's the only drag about the DX6i, no three way switches.
Why all the light weighs you might ask? Well, I may be old but I'm no fool, I'm brushing up on my skills before I put my big hardware on the line. Can't afford to lose a warbird !!
Won't be long though, I'm getting anxious to see how the new P40 will fly, won't be long now!!

Grossman56