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Old Fogey's Cousin...

#1
So about a month ago I discovered flitetest.com. Not sure that was the best thing for my pocket book... At any rate when I saw the Old Fogey I had to build one! I did build one, and it is a great flier. However, I was wanting something a touch more, like ailerons and a little more speed. So, I took the Old Fogey plans and did some sketching. I took two inches off the bottom of the fuse and raised the tail surfaces the same amount. Of course, the under-camber polyhedral wing is probably not the best for ailerons and faster flying so I built an Armin wing with a little bit of dihedral. The initial flights were done with the motor and prop I was using on the Old Fogey. It flew, but the performance was a bit weak.

As far as lessons learned, I think I had too much incidence on my wing. I actually added a bit after the initial build and can probably take some out. It also would have been better if I had used CAD rather than hand modifying the plans, I ended up with just a bit of twist in my fuselage due to cuts being off just a shade. Trim was actually fairly neutral, with the exception of a touch of down elevator to compensate for the incidence. A little more down thrust on the motor might also help. Bracing the Armin wing with dihedral seemed a bit complicated so I opted for some struts from the Horizon Cub. For $3 it's a good solution.

I happen to have a motor and speed control from a planned mikey's Sport Trainer that should give it a bit more punch. I got the speed control soldered up today, so if it's not too windy tomorrow I might be able to fly it with the bigger motor and see what it can really do.

Here's some pictures of the finished plane. Total flying weight with the swap-able pod from the Old Fogey was just under 16 oz. The length is 30 inches and the wingspan is 40 inches.







I apologize for the horrendously bad pictures, a photographer I am not. There is also some really bad video in my Photobucket album. It's been more than 20 years since I have flown RC and was never that good to begin with:eek: The very first flight landed it squarely in a ditch, but no mishaps in subsequent flights.

http://s961.beta.photobucket.com/user/roversgonemad/library/RC%20Planes/Old%20Fogeys%20cousin%20Fred

I will probably close in most of the back of the fuselage, with the exception of a vent to get some air through for cooling. With the larger motor and speed control, I want some airflow to help keep the ESC cooler. Not knowing what I was doing initially, my ESC is probably a little small for the motor I am using. Keeping it slow should keep it from burning up I'll have to do some load tests before I put it in the air. I will order a larger ESC, but they are currently all backordered with Hobbyking:(
 
#2
Is your wing to tail incidence set to 0-0? If so, might not be the problem. When I have to trim down on an airplane whose fundamentals are correct it generally is a little tail heavy, where is the CG on your airplane as it now sits? Is it in front of the Armin wing spar?

Rearward CG can do all sorts of fun things to your airplane. It will be pitchy wanting to dart up and down with small elevator movements, it will also make it not track solid wandering around. Moving the cg just a quarter inch forward could solve all your ills, or give you re-assurance that you're moving it in the right direction. Get too far forward though and it'll be hard to hold the nose up.

One further note, the Fogey is a floater and the prop/motor/esc combo for it does not necesarily translate to a higher speed aircraft. You could simply be closer to a stall then would be comfortable for your plane. But verify your CG first and maybe take it a little further forward and give that a shot. If the CG is in front of the Spar, a popsickle stick or two under the trailing edge will help level your wing out for quick field tests. It's not like we're going to blow a lot of oily exhaust into your fuse.
 
#3
I think you might be right, on all counts, CG, motor, and incidence. I knew better than to mess with the incidence, but I looked at another plane and it had a couple degrees of incidence. I should have stuck with my gut on that one... I flew again with the higher pitch prop and it still acted very similar. I landed and moved the battery forward a tad and it behaved better, but I am very close to stall speed.

Just for fun, I am going to put a ridiculously large motor on it and see what it does (worst case I take out my electrics and throw the wadded up foam in the can after it crashes). This other motor I bought for a Mikeys RC sport trainer and I think I bought way too big of a motor, but it's worth a shot to see what it will do. I have plenty of room to move the battery back and forth to get the CG to work out. Not sure if the air frame will handle the bigger motor, but it's worth a shot.

I am just getting back into this hobby and after being away for more than 20 years, a lot has changed and all this motor, prop, ESC business has my head spinning. Back in the day, I had planes with 0.10, 0.40, and a Craft Air Piece O' Cake with an 0049. Things were much simpler, but then I really never did try my hand at scratch building. I had a Flitecraft Cardinal, and a Carl Goldberg Ranger 42. By the end, the Ranger 42 was a seriously destroyed wad of foam and epoxy...
 
#5
Incidence and balance!!! And a LOT bigger motor!!! It's a screamer!:eek::eek::eek: So my other motor is a Turnigy 3530/14, 1100kv, with a 9x6 prop. I landed after a couple minutes and checked the motor and speed control temps and it seems to be okay, but it was only about 9 degrees F.

I made it slightly nose heavy just to be sure, and it trimmed out really nice!! Full throttle, it really screams and it has fairly quick roll rate. Loops were a little squirelly, but that's likely because of the twist in the fuselage. Total flying weight with a 1500kv 11.1V is 23 oz. I need to get it drawn up in CAD now and cut out out a more square fuselage. With the kinks worked out of the air frame, it should fly really well!



I apologize for the terrible pictures. After I get my foamie mess off the kitchen table I'll snap some better pictures.
 
#6
The better pictures.











The T-28 in the background is the reason I built this plane, wanting to build up the skills and confidence to fly that plane. I am guessing this one might be more of a handful than the T-28:confused: Regardless, it's fun to fly.
 
#8
I totally agree! The white gets lost in the sky really easy. I am leaning towards OD green with some invasion strips. I had to make sure it would fly before I spent too much time on it.
 
#9
So being essentially new to all this I have a propeller question for this plane. I went and used the prop calculator at eCalc and it says my prop may stall.... This prop seemed to have crazy thrust, far more than the plane weighs. The calculator even says it will have 1400+ grams of thrust. Turnigy recommends a 12x6 for 7.4 volts and an 8x4 for 14.8 volts. It seems that the 9x6 should be between the two, and for 11.1 volts a reasonable size. The prop calculator says 1430 grams of thrust and my plane only weighs 650 grams. I know I have enough power to climb straight up and the plane jumps off the ground in about a foot. Would a smaller prop or less be pitch be more appropriate. The prop calculator indicateds a 9x4 is appropriate, would this be a better size?

Mods, if the prop discussion should be moved to a different forum, please do so.
 
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#10
Does the plane fly good now, with decent speed staying away from the sluggish stalling we started with? If so, just realize you have a slightly overpowered plane now and enjoy it. You can slow down your high power speed by propping down. It doesn't sound like you're not hooking up on the prop, but realize that putting a larger diameter, lower pitch prop on a plane is the same thing as shifting from 3rd to 1st in a car. You don't go as fast but it pulls like a mother. If that top speed isn't comfortable for the plane, then your wasting time. From what you've described I wouldn't change anything motor combo side, unless you got a more reasonable motor combo, then I would go down in output a bit.

But what is the fun of that?

Mo POWA!!!!!

And it's an appropriate question for your plane so I doubt it would get moved.
 
#11
now, feed the dog some mixed veggies and chocolate then put em both in a small room.

Translation, some color please?
Here's what you get with two large Hershey bars, spinach, and a black lab;)









He's had a few unintentional encounters with the ground now... It's a few glue sticks and some packing tape heavier. This is the third propeller:black_eyed:

I just painted it this evening, after nearly losing it in the sky. I went out to fly this afternoon and got it in the air and it was immediately lost in the white-ish gray overcast sky:eek: All I could see was the landing gear and the wheels. I was leaning towards the Grasshopper paint scheme, and it's somewhat fitting. It will definitely be easier to see in the air now, at least on overcast days.

I tried an 8x4 prop today and it just didn't have the oomph to really move it around. The 8x4 was just about a 1:1 thrust to weight. I really think it needs an APC 9x4.5. I have a 9x6 on there again, and it rips just like it did before, but it's so fast, without fairly high expos it's a real handful.

I am going to keep flying it and it will definitely make me a better pilot. I need to get my friend, who is a much better RC pilot than me, to fly it and see what he thinks. There's always the chance that I have made a nearly impossible to fly monster. However, I have had more good landings than bad, so I'll just keep trying.
 
#16
This project looks amazing, I'd love to get your CAD drawings if you have them available!
Let me get a few kinks worked out and I'll get some full size pdf plans posted. If the weather agrees this weekend, I'll do some more flight testing. I am currently leaning towards a wing with a little lighter per sq. ft. loading. I currently have a 7 inch total chord, but an 8 inch chord will will add some area, and that combined with a slightly lighter power plant package should make it a good flyer. Being a nerdy engineer I always have to over analyze things a bit:D
 
#17
Analyze this (I was just thinknig about my ships) first cool summer night your paper airplane is going to get all dewy, and that's gonna suck for the both of us. Unless you covered your wing with tape first.

Did ya? Thinkin about applying some clear packing tape here. Wonder if I can get some of that clear laminate stuff the control line combat guys use.
 
#18
Let me get a few kinks worked out and I'll get some full size pdf plans posted. If the weather agrees this weekend, I'll do some more flight testing. I am currently leaning towards a wing with a little lighter per sq. ft. loading. I currently have a 7 inch total chord, but an 8 inch chord will will add some area, and that combined with a slightly lighter power plant package should make it a good flyer. Being a nerdy engineer I always have to over analyze things a bit:D
Haha, I'm going to have to take your word for it, looking forward to hearing about the FliteTesting ;)
 
#19
Analyze this (I was just thinknig about my ships) first cool summer night your paper airplane is going to get all dewy, and that's gonna suck for the both of us. Unless you covered your wing with tape first.

Did ya? Thinkin about applying some clear packing tape here. Wonder if I can get some of that clear laminate stuff the control line combat guys use.
I did think about that, but I honestly figured this one would be a wadded up ball of paper and foam before I had a chance to get it wet;):D This one only has tape in a few strategic areas. Full tape is slated for the next prototype. One good thing, it's very arid where I live so dew is actually a rare occurrence. Nevertheless, once the design is more final, it will be taped.
 
#20
Same here. It just occured to me when I was dreamin of SPADfest and how dewey everything got last year. My planes, my truck the underside of my Hammock Tarp. How wet I got when I slipped getting up and banged that dang tarp. What a rainstorm!