combatpigg

My Feedback: (3)

Thanks..!
It was fun to be out there again but surprising to see how out of tune my eys are. Too keep in the groove, it just isn't a good idea for old folks to go long stretches without doing things like this.
Just another month or two of car restoration work to go and this RC hobby will take over again.
I'm really burned out with doing rust repair and body work over the metal patches. I'll bet there's close to 200 feet of weld on the car I've been restoring from the rotted out frame on up. Reason why so much weld is I hit the patches on both sides with the MIG welder so that when the top side is ground flush there is added support on the underside. Ford used odd gauges like 17 for the exterior and the closest I can get is slightly thinner at 18. It makes forming a patch easier, but it is easier to screw up .065" thick metal when the welds have to be finished with grinding and sanding.
No more uni-body cars after this one for me. Too much work and some of that work is doomed to fail when certain areas that you can't get at come bubbling to the surface a few years after the work is done.
The pre WWII Fords had thicker sheetmetal and that metal had a high nickle content, so they are naturally more rust inhibitive.
That's the way to go.

iron eagel

Cp I had to drill the one on the stingray out to 5/16 (because that's the prop adapter I had), and I had that one spinning up to 27,600 rpm, they figure the limit on it to be something like 36,000 (190,00 divided by diameter). I had also tried a 5 X 5.5 apc that one spun up to 28,000 rpm so I think they may be able to take the 30 K figure.
I read some guys in Europe have used them to make molds (the 5.25 X 6.25 and 5 X 5.5) to make carbon fiber ones, they were using 6, 8 and 10cell setups spinning in the 40-50 K range.

iron eagel

With the 5 X 5.5 on a three cell it sounded like my old Pico in the air, some guys who heard it thought it was a two stroke not an electric.

combatpigg

My Feedback: (3)

That's good to know. Those props are only $2, so I might order some. I tried the 5x5 E prop with a ASP .12 on a small delta and the launches were very weak, but the model dopplered at 130 mph with a $30 engine. Those props look so weak and dangerous, but I wasn't worried about a $30 engine going on a shaft run.
Right now, the combo on this plane acts like it could run for years with very little wear. Both landings yesterday were with the prop at 12 O'clock and none were broke on the short grass. The plane glides at 4 feet for 100 yards and set down real gentle.
I'll try shortening this 6.5 x 5.5 to 5.5 x 5.5 and see what happens. It won't do much good until I get the doppler program and camera going again. Without being able to verify the speed I would have to fight the overpowering urge to go on Youtube and claim that it did 194 MPH.

iron eagel

Yea, I know about the overpowering urge as far as speed claims.
I'm willing to bet that with the 6.5 X 5.5 if you got it to unload it's probably a lot faster than you thought.

Edit to add:
I think that spinning these up in the 30 K range is right on the hairy edge of what they can take. I know Mike Connor had 5" APC one up in the 50 k range once, before he blew the motor up, so they have some potential. I have to admit that I tend to stay behind the plane when running them up even at 26-28,000 rpm range, I not all that confident of their longevity operating in this range.

MJD

My Feedback: (1)

Steve Wilk has a number of 5.xxx" CF props that are 8 bucks each. Some are lekkie prop copies.

iron eagel

That is probably the better route to go, both Mike and I were using these on $70 electric motors that both we considered to be expendable. With a more expensive motor or engine it may be well worth the extra $6 just as insurance for the engine. I just wanted to be sure CP understood that I wasn't trying to paint a picture that was all sunshine and roses. Spinning a prop over 25,000 rpm your getting very close to the point of achieving critical mass as far as I am concerned.
This range of operation with these props is just about as gray of an area as the props themselves.

combatpigg

My Feedback: (3)

What APC has no control over is the guy who drags a blade on landing, gives it a 1 milli-second look, then fires the engine right back up for another flight.
After flying the model gets tossed in the car and the wafer thin prop has an unprotected ride home.
APC has been very conservative about safety over the years. They have recalled props that had failures reported and their website talks about the realities of high performance usage. They also sell millions of props all over the world that are revving to 50,000 while I type this message. A blade letting go at 30,000 would be devastating and my starting procedure right now needs some cleaning up.
Ideally it's done like the C/L Speed guys do it. They have a starter motor with rubber cone solidly mounted to a stand with a foot switch. Then they simply approach the starter while holding the model behind the engine and there is never a single moment when the guy handling the plane is in the arc.

The 5 inch props I got from Steve might not have enough hub for this engine's 5/16" prop nut / spinner nut.
My

MJD

My Feedback: (1)

You've already been prop shopping I see.

How is the prop shaft length? The Profi combat .061 I have has a prop stud that is evidently trimmed to the length needed for fine pitch combat props and no more.

iron eagel

One of my biggest fears is not so much the prop but the 1/8 inch shaft holding it and the prop adapter. But I also wanted to let you know I accept the fact that I am getting close to the "legal limits" as far as operation, kinda like running a pontiac 400 with 12:1 dome pistons.
I went back and looked up the actual data I had on the APC props rather than just trying to remember it, with an electric this is the load the prop presented to the motor so that's all that is needed to spin it up to that rpm. There is a couple of other factors about why these were the peak but it show you what type of power it takes to spin the prop to that rpm. With the 6.5 X 5.5 we never tried any downhill to peak it out so in reality it may have been capable of a bit more.

6.5 X 5.5 power 1.24 hp (935) watts, 26,000 rpm
5 X 5.5 power 1.16 hp (871 watts), 27,171 rpm
5.25 X 5.25 power 1.016 hp (762 watts), 27006 rpm.
This should give you a fair idea of the actual power it took to spin theses props to that rpm. If you have a bit more hp than that available I would expect the max rpm would be much higher (at least equal to the % of more power you have available) like you said you had a bit more hp and rpm.
For what it's worth the only prop that I have seen any damage to was the 5.25 X 6.25 that ate dirt on a less than perfect landing well landings actually, busted up the nose pretty good as well. So far no signs of wear with the 5/16 bore for the prop shaft.

iron eagel

Guilty.

iron eagel

I just took a look on the APC package for the 5.25 X 6.25 guess what they state you can bore it out for 0.316 shafts.
Talk about a bad case of FTRTFI.
So 5/16" legal by their own standards...

combatpigg

My Feedback: (3)

That's identical power to what I have here.
My tach just croaked, but I chopped the tips off yesterday's prop and now it is a 5.5 x 5.5.
The engine actually said "thank you" after the test run was over. It still has a ton of pull with the 5.5" prop and I've got no doubt that this will at least fly the plane.
Yesterday's static thrust was something like 3.5 pounds going by the calculator.
that's 56 ozs of thrust pulling 23 ozs [fueled]
I just relaxed my grip on the hind quarters to launch it.

combatpigg

My Feedback: (3)

That's the way this engine is. too. The stubby output shaft saves some engine damage and less mass hanging way out lets the combat models turn tighter. None of the things these engine builders do is without purpose, same goes for the RTF planes coming out of Russia. Those people know how to make due with less resources, then when they get access to equal resources....look out..!

iron eagel

That's cool sounds like it was sort of fun. Keep in mind because of the 43 inch wings I never was able to get anything under a 6 inch prop to go fat enough to get the prop out of the stalled condition so you are probably going to get a lot better results with what you are doing, given the power you have to work with.
Given APC says you can bore these out to 0.316 inches it sounds like a case of smoke them if you got them to me as far as the 5/16" shaft.

combatpigg

My Feedback: (3)

There.
A little glass, bondo, paint and out the door.
It's just a piece of flat 1/16" balsa, so it can be pruned at a later date if I feel daring.

iron eagel

That was quick!

MJD

My Feedback: (1)

Ought to be robbing all of 2 mph. On the other hand, it could be robbing less than gently wobbling around at speed.

Depends whether you want to be a rock-stable kind of guy or live-on-the-edge..

Is it consistency time or go for the record books..?

Whatever the heck this model actually qualifies as - perhaps FAI F3MS / Speed, Scale, Mammal? - it's sure to be the fastest one around.

iron eagel

I think he has got it set up with every intention of "fine tuning it".

I think it is a bit quicker than even he thought it would be, I am pretty sure this is going to be "pretty extreme" for a 1/2 A. Those motors out of the Ukraine are pretty darn awesome, on a feather weight airframe, it has got to be able to move pretty briskly.

combatpigg

My Feedback: (3)

Now that the model has a huge WWII bomber-like dorsal fin..those tip fins might get amputated.....they "clash" with the looks of the dorsal fin now. They took a lot of work to make..but it's probably a 1 :10,000 chance that they are breaking up those evil vortexes well enough to pull their own weight.

I can not remember the details, but I did manage to build a plane that had barely enough fin to fly. It swam like a fish while it flew. You could see it wobble back and forth like a swimming fish on straight, level passes.

iron eagel

I think I'd leave them til you do a run that you can measure the speed first.

combatpigg

My Feedback: (3)

Too late.
I think this will go mo betta with the moustache trim.

iron eagel

combatpigg

My Feedback: (3)

I re-learned something today.
Lateral balance is important too.
After clipping off the winglets [eyeballed the cuts] and doing a "slam job" on a bigger fin I was in for a surprise with today's first launch.
The model veered to the right and came to a sudden stop. It didn't break the prop, but the impact cut the fuel line where it passes through the firewall.
I figured that I did a sloppy job on the fin [a layer of 1.5 oz FG on both sides of 1/16" balsa], so I hand formed it to make sure it was perfectly straight.
Next launch was just as bad, but by holding hard left stick the plane barely avoided the ground as it veered right, then climbed away to what was a nice flight.
After the flight, I checked the lateral balance and the starboard [right] wing panel was way too heavy. This plane has an assymetric layout and I should have checked the lateral CG before covering the wing.
I didn't bring any tape, or I would have taped a quarter to the port side wing...so I popped a hole in the wing and used it to hold about 4 inches of solder. Not a perfect balance job, but it made a huge difference for the rest of the launches.
I'm still not able to get the plane to do "dignified" launches, but at least there is full control authority in all directions now.
For some reason the elevator trim isn't working on this Spektrum Park Flyer radio, so nice long, low passes tend to climb. I just need to get into the instruction booklet to see what programming I'm failing to do for the trim.
I was using a 5.5 x 5 [cut from 6.5] and the model seemed like it was doing 120 mph [with a lump of solder on one wing tip]
The engine was hard to start with the shorter prop..or maybe because this 4 year old fuel is weak. This needs to get sorted out before going back to the field. Same goes for the old video camera that wouldn't upload..more time needs to be spent sorting that out.The plane looks like it went 4 wheeling because after it ran out of fuel on the last flight of the day.... it seems that I lost orientation and stuffed it. It was about 400-500 feet away instead of the usual 300 feet when the engine quit. The model needed to be pulled out of the mud, since it lawn darted in. The prop is OK, believe it or not.

iron eagel

Glad to hear that she survived it all.
As far as the video, did you get a new computer? I found that with windows seven my old Sony Video camera wouldn't work via the USB any more. I had to get a USB adapter to take the video off the camera using the video and audio outs on the camera.