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Here we go again, H-9 P-51 Conversion

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Old 07-26-2004, 10:57 PM
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Longarm
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Default Here we go again, H-9 P-51 Conversion

Some of you may remember my first P-51 conversion, succesfull two flights and death on the third flight. Well I have another one in the making. I is 95 percent ready. I have questions for you A"GURUS" out there.

I have the AXI 4130/16 again with a 6S2P pack of Tanic 2550's. Will deliver a constant 60 amps, or a constant 12C. I have tested two props, A 16/10 APC pull 55 amps at full throttle, and a 14/10 APC pulled 38 amps at full throttle.

Would you keep the 16/10? or try another prop, like a 15/10, or a 16/8?

Another question is about the retracts. I cant seem to get the retract servo in the sweet spot. When the retracts are extended in the down position, the servo is drawing .5 amps. When the retracts are up, in the closed position, it is drawing 0 amps. Is that OK? I dont want that d@#$%@#%$@# m thing to overload my other servos like the other setup and watch it spiral to its death too.........

I am thinking of just locking the landing gear in the down position and fly it that way until I can get some Robart, or better retracts that are more reliable.

Suggestions please.

Appreciate the feedback.

Longarm
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Old 07-27-2004, 06:06 AM
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Default RE: Here we go again, H-9 P-51 Conversion

toss the retracts and buy spring air retracts. they use air to operate and you will never have to worry about overcurrent on your retracts as you use a small servo to oerate an air switch. the air switch turns on the air pressure to raise the retracts. when the servo switches the air off they come down using springs built into the retracts. get the version that uses the 3/16 wires - the 5/32 wires are a little wimpy. but even the 5/32 wires will be much better than the ones that come with the plane.

by the way i also angled the retracts forward so the axles are even with the wing leading edge when extended. i did this by adding spacer to the back side of the gear mounts. i also moved the retracts in toward the fuselage 1 1/2 inches, which still gives plenty of ground clearance with a 14 inch prop and gets rid of the stork look (tall skinny legs ). you will need to grind some wood off the gear mounts to get the spring airs to fit.

edited to give the spring air site www.retracts.com - buy the 100 series-

ed
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Old 07-27-2004, 07:41 AM
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Default RE: Here we go again, H-9 P-51 Conversion

One thing you don't want to do is push these motors past their constant current ratings for long. 40 Amps on a continuous basis is about it for the AXis.
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Old 07-27-2004, 08:28 AM
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Greg Covey
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Default RE: Here we go again, H-9 P-51 Conversion

Hi Marshall,

I would recommend keeping the 16x10 prop. Although you'll rarely need to use full throttle, you'll have great burst power when needed for giant loops, climbs, take-offs, etc. In other words, by using throttle management, you have extended the dynamic range of your power setup.

Changing to Robart struts won't help you find the sweet spot on the retract mechanism unless you plan on replacing the entire retract. Although I am still using the stock gear, I have had no real problems other than an occasional bounce on landing. I am considering a switch to Robart struts before the NEAT Fair just to add some shock absorption for landings to stick better. This does not, however, change the stock retract mechanism other than the gear mains. Here is a link to Tower Hobbies for the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXES70&P=7]Robart 653L[/link] Left Strut that I am contemplating on using.

Is this the same retract servo from your original P-51 or a new servo? Also, it sounds like you need just a small change in your linkage setup to remove the 0.5amp endpoint draw. Do the P-51 retracts rotate 90 degrees like the H9 Corsair?

Recall that a second UBEC can also be used to eliminate your fears of the retract servo taking out the receiver again.

Regards.
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Old 07-27-2004, 10:07 PM
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Default RE: Here we go again, H-9 P-51 Conversion

I finally gave up and asked my local hobby shop expert to tweek the darn thing. After trying for 20 minutes, he got it right. I was ready to pull my hair out. Retracts are fully extended and pulling no amps. Are fully retracted and pulling no amps. So that problem is solved.

Next question. I have a dead area in my throttle stick.....from 2/3rds to full, there is no change in the full power.....When I have tried to correct this in the past, it changes the dead space to the first 1/3rd of the stick travel. Any suggestions on this one? The LHS guy told me to try and set the throttle at full EPA on both the low side and the high side of the throttle and then reset the speed controller. I have the Hacker Master Speed controller in the plane. Will that work?

Greg, it is the same servo...It is working correctly......

The Lipos made the plane two pounds lighter.........by the way.....

More progress tonight. Plane may go up this Saturday....I am undecided about the second UBEC. Oh. and the retracts are not like the Corsair. The fold in from the outside area of the wing, under the fuse. They dont rotate like your plane.

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Old 07-28-2004, 10:59 AM
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Default RE: Here we go again, H-9 P-51 Conversion

Marshall,

My guess on the throttle issue is that the Hacker ESC either needs to change mode or re-learn the throttle limits. Personally, I don't like the auto-learning modes as it requires a full throttle run on every power-up so I use the pre-programmed airplane modes. The Hacker ESC may have many options here for you to choose from.

Two pounds lighter, huh! It's like you dropped all your bombs and you're ready for a real dogfight!

I've submitted a request for an isolated retract servo output to Kool Flight Systems. They already released their new 6v output version and I love it!

Good luck this weekend!
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Old 08-01-2004, 10:39 AM
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Default RE: Here we go again, H-9 P-51 Conversion

I maidened the new "stang" this morning. All is well. I was nervous as could be. I was the only one at the field this morning. I range tested it by myself and all looked good. There was a constant 5mph or so wind coming pretty straight down the runway so I went for it.

Got her up in the air and could immediately see a big difference from the previous setup. I have a Tanic 6s2p pack that has 5100 milliamps total, with the parallel setup. The batteries are 2550's that supply 30 amps continuous, 60 in the 2 parallel.

I replaced the stock tires with foam and left the pilot out. This with the LIPOs made the plane 2lbs and 3ounces lighter than the previous "stang" that I had.

My new AUW is 8.5 lbs on the dot. I tested , taxied twice, then took off and flew a 10 minute flight. Total time using the juice from the batteries was 12 minutes. I will charge up and post how much "Juice" was drained from the battery.

Man, this thing sure slows down nicely with the light weight that she is now.

Well that is all I have for now.

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Old 08-02-2004, 10:01 AM
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Greg Covey
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Default RE: Here we go again, H-9 P-51 Conversion

Marshall,

Great job! That dreaded fear when flying a new R/C plane is actually something that we keep coming back for more of.

A 20% drop in flying weight makes it a whole new ballgame. I'll assume that the properly adjusted retracts worked well as you made no comment on them. It was a good move getting some help to adjust them as I have done the same thing.

Unless you flew the P-51 really hard, i'll guess that your charger puts back only 3AH or less.
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Old 08-02-2004, 11:07 AM
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Default RE: Here we go again, H-9 P-51 Conversion

I have two 3s2p packs that I run in series that makes it a 6s2p. I have to charge them one pack at a time because I have a Triton charger. One pack took 2630 Mamps and the other took 2730 Mamps.

I started and stopped my stop watch when I was doing the testing, taxing, and then the flight. The total time the batteries were working was 12 minutes. I had a ten minute flight of the 12 minutes. I AM VERY PLEASED with that. I was not flying it hard, especially on my maiden flight. I did some mild aerobatics with it though........Rolls, inverted flight, and some loops........

Thanks for the Congrats............

Longarm
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Old 08-08-2004, 04:26 PM
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Default RE: Here we go again, H-9 P-51 Conversion

Here is a video from Sunday, hope you who check it out enjoy.

This is the second flight of the new "Stang". This time it was 9 to 10 minutes and put back 2400 Mamps into the battery.

Thanks goes out to Dave for filming it and putting the video together.

Longarm


http://www.mustangone.com/images/H9P51.wmv
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Old 08-09-2004, 10:08 AM
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Default RE: Here we go again, H-9 P-51 Conversion

Looks great!

Nice tail lift on take-off too.

and I thought Florida was sunny...
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Old 08-15-2004, 10:59 PM
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Default RE: Here we go again, H-9 P-51 Conversion

I had my 3rd and 4th flight today and I have questions to all you experienced flyers out there.

Set the stage by saying that I am a new flyer. I started in Feb. of this year and progressed rather rapidly (so I have been told ).

My first flight of the day required more right rudder input on the take off than what I remember from the previous two flights. Maybe I was just excited and nervous because I had more eyes on me today than normal. Anyway, my question is about level flight and landings. I had the plane trimmed to fly level at a slow flight. My way of flying is aerobatics followed by a dive and a nice pass infront of the field. When I pick up speed, either from a dive or by hitting the "juice", the plane wants to gain altitude. (you can see this in the video on the dives, I am not giving it up elevator when it climbs out of the dives).

I gave about 2 or 3 beeps of down trim and was flying at faster than the previous speeds shown in the video and was pretty much level. When I came into land, I misjudged the distance and according to the spectators, gave them a pass at around 12 feet in front of them.....It didn't look that far out when I was lining up, but when it got in front of me, I could see that it was further away than it needed.

Ok,,,,,,cut to the chase. Because of the downward elevator trim "beeps", when I came into land, the angle of the plane was pitched forward a little. As a result, I had a little wild landing. The front tires touched and it started a slow motion nose over. I began trying to feed in some elevator to get the tail down, but the prop got sanded a little. It then porpoised a couple of times on me because of adding the elevator in there to get the nose up / tail down. No damage other than I had to bend the left gear out a little so the retracts wouldn't bind and the prop got an 1/8th of an inch shave.

Is this normal? Should I take off, feed in the 2 or 3 beeps of down elevator to fly and then feed in the reverse trim beeps for landings? I dont have one of the radios with the flight phases on it, so dont suggest that. The Futaba 6EXA wont allow that.

I am talking myself into a better radio.....any suggestions on a better radio......under 300 dollars that will last me a lifetime.

Oh....two flights on the one charge....9 minute plus taxi back...then a 7 minute plus taxi back. Charged pack and put in 4500 mamps.........from the possible 5100 mamp battery. Put the plane through its paces today.......

Long winded I know.

Thanks......

Long "winded" arm...............this time.
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Old 08-16-2004, 08:52 AM
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Default RE: Here we go again, H-9 P-51 Conversion

Which prop did you decided to fly it with?
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Old 08-16-2004, 12:26 PM
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Default RE: Here we go again, H-9 P-51 Conversion

16/10 APCe.

Static test at WOT Sunday was 50 amps. I never use full power for long periods, just short bursts.

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Old 08-16-2004, 09:41 PM
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Default RE: Here we go again, H-9 P-51 Conversion

i would recommend trimming it to fly level at whatever power level you wnat to normally use during regular flight. then of course the plane will tend to descend when you reduce power for landing. my h9 mustang takes some distance to slow down but then mine has an st g90 engine. you just need to get used to how far away from landing, at what altitude, you need/want to reduce power for the plane to come in for a landing at a gradual descent. it will take few flights to get used to how much power yu want to use as you prepare for landing. i usually go to about 1/4- 1/3 power and extend the retracts, then i make a pass in front of me to check that the retracts have extended properly. then i make my actual landing approach.

if your transmitter gives you the option of using exponential on the elevator i recommend using about -35% expo on the elevator. this makes the elevator less touchy at low speeds whenyou want to flare the plane for landing. as your plane comes out of the last turn i am usually at about 15 feet altitude and 200 yards out from the runway, and i go down to "idle" about 100 yards out. as you approach the end of the runway it should be about down to landing speed and you will be using a little elevator to hold the altitude and this will help bleed off speed. you will start using the elevator to flare the plane and as you come onto the runway the plane should be maybe 3 feet above the ground.

then as you get to the actual landing i flare it a little more and let off some elevator to let it settle on the mains, then i just let it roll out.

i hope this isn't too detailed - i just thought i would explain how mine lands best for me. others may use a different technique- whatever suits you best.

ed
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