jpdjr

quote]ORIGINAL: jecchile

ONE IMPORTANT QUESTION - DID YOU CHECK THE BALANCE ON YOUR MPXT?
For what you say - it sounds like it is tail heavy - if so, moving weight to the front part of the plane may help things...
Good luck.

[/quote]

When I put it inverted on my GP Balance Machine at the recommended CG, it noses down hard. When the plane is sitting level, the CG machine reports the measurement at 51mm. I also tried Doc's suggestion of balancing on the spar, but even there it comes out nose heavy. What I find so strange is that it is nose heavy on the CG but wants to climb like crazy.

Is it possible that the 10x7 SF eFlite prop could be contributing to this tendency? If I move the battery further back to move the CG to the recommended point, the behavior is even more exaggerated! Should I switch to an APC 10x8e with my stock 450PNP motor?

As I have it trimmed now, it's still nose heavy but requires 5-7 ticks of down elevator to minimize the climbing issue to the point that it only climbs slightly when the airspeed increases above 50% throttle and it flies okay, but not rock stable, but then I am not sure this plane is supposed to be rock stable in flight without hands on sticks since it is not a trainer.

I like the plane and enjoy flying it but this inability to get the plane to fly level is really bothering me and makes me very nervous every time I fly it.

jecchile

My Feedback: (3)

The only other thing that could be causing that behavior, if it is not tail heavy, is the wing incidence angle... make sure that the stab and the wing are both at the same level. Also, make sure that the engine has a couple of degrees of down thrust... I don't think the propeller size and/or type will have that effect on the airplane. If the incidence angle is the problem, a small shim under the leading edge should fix it.
Good luck...

jpdjr

It's me posting again. I just spent the last hour carefully adjusting the CG to the recommended measurement using my 3 batteries (e-Flite 2100, PZ 2200, PZ 1800). I was able to mark locations in the battery tray for these batteries so that the plane would sit beautifully level at the recommended CG (2.75" from leading edge). For the larger 2 batteries, about 1/2 of the battery length is beyond the back of the battery compartment and extending into the canopy/wing area. For the PZ 1800, about 75% of the battery is in the compartment.

I will not have a chance to test fly the MPXT in this configuration until tomorrow, but hope that the plane will be more stable in the air and not want to climb so aggressively on its own.

I welcome any other suggestions for this plane as I really think I will love this plane once I can get it to trim out properly.

Jim

jpdjr

Finally got the chance to fly the MPXT after spending that time working on the CG issue. She flew really great today. Still wants to climb like crazy at full throttle, but it only took 2-3 clicks of down trim to get her flying level. She flew with minimal down stick inverted as well and generally just flew where I pointed her.

After the first pack with the stock 10x7 prop from the PNP kit, I removed that prop and installed a Master Airscrew 10x8E prop. What a difference that made! The MPXT just screams through the sky with that prop and goes vertical with quite a bit of authority. Not unlimited, but more than sufficient for my skills and desire right now. The only downside is that she now doesn't slow down as nicely as she did with the 10x7 prop, but I'll adjust to it. I got in 3 flights with this prop but wound up having to make 2-3 attempts before getting her down safely.

Thanks to jecchile for the suggestions on the CG issue. It's nice to have that sorted out and begin to acclimate to the MPXT.

jecchile

My Feedback: (3)

You are welcome - I hope I was able to help.................Have fun.

Texacate

Hi all. It's a sad day in MPXT land, for me. My plane is currently sitting about 4 -5 stories high at the very tip-top of a monster-huge cottonwood tree. Lesson learned. That tree is taller than you think!

jecchile

My Feedback: (3)

WOW... sorry to hear about your plane... will you be able to recover it from the tree?...
I just maidened mine on Wednesday - took my sweet time getting it ready... needed up elevator and right aileron in order to get trimmed... after that it flew GREAT. It has a 450 engine (got it from Heads-Up RC), a 10x7 prop, 2200 mah pack and a 38mah ESP with BEC. The plane will go straight up with that set-up. I usually set up my flights at 10 minutes and the battery packs are not even warm when I land.
My stable consists of a Parkzone Corsair, and F27-C and the Mini Pulse XT... all the planes fly GREAT.
Have fun...

phillipmorris

This plane is terrific, I unfortunately flew in over 20 to 30 MPH wind gusts, only few flights, got above me by the time I turned around it was decked into the turf, ripped off the wheels but will have this one going again and more cautious on wind conditions...Its the PNP version all set to go and even with an undersized 1800 battery it rips the skys, this puppie handles very well, its a winner.....keep the nose level and down for airspeed it deadsticks beautifully...even on the grass...

Next change will be nylon screws for the wheels...

Prized planes todate
Super Cub, later Night Flights
Hanger 9 T34 Mentor, wow progressive settings even I can land this one, comes in like an airliner, awsome..
Mini Pulse XT, responsive and easy aileron flyer, suggest abit of expo for the newbie, love it ..

Flyer88

Thought I would share some mods on the spinner of my Pulse. Cut off about 1/2 inch to improve cooling, as long as the spinner has a open back plate.

I'm running a Common Sense E5-L13 which mounts up to the factory holes (450 size 1300 kv) very small and puts out 285 + watts running a 9 x 7.5 SF prop. 10min plus run time with full arobatics on 3s 2200. The motor is running on the top end of it's limits and gets warm so I added more cooling.

This plane is my winter park flyer and I can not begin to tell you how well it flies !! Knife edges for ever and flies inverted with not inputs, very well balanced plane.

Flyer88




Extra cowl cooling ........ Parkzone Digital Metal Gear / fiberglass rod

Snoopyxupery

Mini Pulse with parachute.

http://www.youtube.com/watch?v=KbzXHKC63M8

Snoopyxupery

http://www.hobbyking.com/hobbyking/s...7b48316ff0ac7f

Brian Patrick

Just got my new MiniPulse XT PNP, but the ESC doesn't say whether or not it has a built-in BEC. Does any one know the asnwer?

djdavidcp

I've had my Mini Pulse for over 3 years. I just recently started flying it again. I had forgotten how great this plane flies. Here are a couple pictures from my last outting. I really love this plane.

motoman97

Stock ESC has a built in BEC i think its 2amp

jpdjr

The stock ESC is a 22 amp ESC with BEC. Here is a link to a [link=http://www.horizonhobby.com/ProdInfo/Files/EFLA7310-Instructions.pdf]PDF[/link] with information about the ESC and motor in the Mini Pulse XT PNP.

Hope this helps!

Brian Patrick

Please disregard this posting.

jpdjr

Brian,

I believe the stock prop for the Mini Pulse XT is a 10x7 Slow Flyer electric prop. You could optionally put a 10x8 Electric prop on it. I fly the 10x8E prop myself, but would not recommend it unless you are comfortable flying the Mini Pulse with the stock prop. The Mini Pulse flys faster with the 10x8 prop and needs a steady hand as it does not slow down as much as with the slow flyer prop.

Hope this helps!

Good luck and good flying!

Brian Patrick

Thank you!

RZielin

My Feedback: (1)

Here's my landing gear support solution. Thought I'd turn a bad event into something useful, as my horrendous crash allows me to photograph my structural modifications better. I was impressed by how well this landing gear structure held up, as the entire nose was obliterated on impact. Prop shaft bent 45 degrees, battery punctured by engine mount bolts, cowl jammed back 2 inches and lots of sawdust. The entire bottom fuse structure however, remains perfectly intact!

The impact did not involve the landing gear, which did not hit ground and sheared off the nylon bolts uneventfully, so I cannot guarantee this structure would hold up as well for its intended purpose (impact on the landing gear). However, it did manage to distribute a tremendous nose impact force diffusely enough to remain unscathed while the rest of the front airframe imploded. I suspect it would do equally well on a hard landing gear hit with steel landing gear bolts.

Hopefully the pics are clear enough. The idea is to bolster the landing gear mounting area against a rotational or twisting force when the gear strike something. This would push the aft edge of the gear up into the fuse, while the front edge pulls/rips down and out. Therefore, I angled two braces, in front and behind the gear mounting plate bulkheads, with their forward edge glued to the bottom fuse plate/bulkhead junction, and their rear edge elevated and glued higher up on the next bulkhead back. Looking from the side, this creates wedge shaped "box" structures in front and behind the gear mounting plate. Note this requires notching the aft brace where it interferes with the wing dowels.

I added a simple "roof" shaped brace over the LG mounting plate, to distribute any forces to the bulkheads, and thereby to the wedge "box" braces fore and aft.

Note that each of the "wedge/box" brace pieces needs to be a trapezoid in order to weedle and slide it into place through the bulkhead cutouts. (The front edge must be about 3/8" shorter than the rear edge). I lightened the front brace with holes, and it held up well so I'd recommend lightening the rear one too. I was too lazy at the time. Given how well this held up, this is probably structural overkill, and should be built with lighter ply or even 1/16" basswood (with grain front to back, not side to side) to save weight. Also forgive my sloppy epoxy job, but hey, it held!

I already have a replacement fuse, but cannot bring myself to pull the servos and trash the old one. I'm trying to rebuild it, despite the fact that 10 hours of my time is worth far more than the $50 and 3 hours to fit out the brand new one. Such is the insanity of my RC airplane disease. Does anyone have a "fix" for that??

Winnitwo

Hello to everybody from Germany,

I found this interesting forum and I just want to show some ideas.

To find optimum CG I had to put my battery in the area above the wings, what is far behind the foreseen area by design.
So I designed a battery case.Thedimensions are shown onthe drawing included The backside of the battery case is holding the receiver. I also found my own way how to fix the battery. I just clued in some small side walls (see photos) thus I can put in a styrophone to clamp the battery.Gives the battery some buffer zone in case of frontal crash.

The ESC is mounted on the lower side, what has the advantage, that in case of a crash the battery won't destroy the ESC.

Wheels: I found some nice 60mm foam wheels. Hopefully for some good landings!
I put in some photos which are perhaps better than my English :-)


best regards
Winnitwo

RZielin

My Feedback: (1)

Beautiful modeling and drafting work Minnitwo!

How are you anchoring those aluminum landing gear braces inside the fuselage? Did you add some light ply where the bolts come through, or just epoxy the balsa there? I wonder if you could get away with nylon bolts for the landing gear (at least the two sets that hold the braces), as well as replace the aluminum bars with thick plastic and shave some weight. Someone else in this thread used one wide plastic plate.

Your tray is a great solution. I gave up on the tray extension idea because I couldn't slide the battery way back with velcro on it. I didn't think of removing all velcro and just wedging the battery in. Nice! (Kind of commits you to one and only one battery size/width/weight though, unless you fuss with foam shims on the sides and rear of smaller batteries to get the CG and fit right).

The wheels are beautiful but also look heavy. Where did you get them? While this is a heavy setup, the tray looks preferable to adding tail weight. At least all your weight is functional (and pretty). I wonder though if a 450 motor could fly this much weight around. Are you using the 480 motor?

Were you able to compare flying characteristics before and after the added weight? I wonder how much faster she needs to fly this way, and if any other flight characteristics changed with this much weight.

Winnitwo

Hello RZielin,

Thank you very much for your compliments!

As you mentioned correctly, the anchoring of the landing gear is done by some 3mm wood plates which I clued inside the fuselage. Very simple, just like a wooden washer. See the photo of my crashed MP.

I also had the idea with the nylon bolts, because the four additional screws with washers and bolts might add some weight - this is correct. My idea was, to use 6 nylon bolts, so also to replace the 2 brand steel bolts. And here the problem started. It's Germany here and there are no inch nylon bolts here. So I would have to use M4 or M5 nylon bolts, what means that I have to bore away the clued in nuts of the original brand bolts. Didn't want to do that, perhaps in the future.

But basically I'm sure that you can replace the alu by plastic and the steel bolts by nylon, why not? I've seen the plastic plate "500 threads before" also. Good idea, which inspired me to aluminium :-)

The tray:
I really like it. Just by varying the thickness of the styrofoam inlays, I can put in whatever batteryI want. I can put the styrofoam before or behind the battery, thus I can vary the position of the battery , too.
And big advantage is, that the battery is wedged, but in case of crash has some freedom to move without destroying itself or other things. After my first crash I always think in terms of crash now :-).
Anyway, I'm only the technician, my son is the pilot, he crashed it. Never mind.

The wheels:
Internet adress is: http://www.rc-toy.de/RC-TOY-SHOP/RC-...eder/index.htm
Price is 3,50 euro - what is not very much in my opinion.

It's a german adress, of course. If you absolutely want them, let's see whether we can find a way. Let me know. The weight: Look at the photos, the original wheels with wheel pants are heavier than my 60mm wheels.
I have to admit, that the wheel pants are the heavy part. The weight of the original brand wheels is 9gramm (4,5 gramm each wheel).
With the 60mm wheels I don't use the pants of course. The wheels are kind of foamed rubber, so they are elastic and not heavy - I would say perfect for the MP.


I have the 450 motor and it is perfect. More than enough power, no sign that there might be too much weight! So don't be too concerned about the additional weight, I think it really is not enough to have any impact at all - we didn't feel anything negative.

nice greetings from good old germany

Winni

Can anybody tell me why I always have this big line of advertising on the top of my posts? I would like to switch it off.

RZielin

My Feedback: (1)

Winni,

Great info, I'm glad she flies well with the weight. Mine is sure to weigh as much when I finish my repairs (as you can imagine from my crash pics. I also use the 450 motor (we're in the minority here).

The add banner is just a nice "feature" we in the US give as a bonus to our Eurozone friends. It's sort of an American "initiation" rite into the world of capitalism. You can now consider yourself a fully assimilated tool of our "free" market system.

This link is right from your very own add banner! http://rtlfasteners.com/Merchant2/me...ategory_Code=N

You need 4-40 size nylon bolts for the landing gear blind nuts. #704 and 707 at RTL Fasteners I believe. Make sure you get them long enough to extend inside past the end of the blind nut, so you have something to turn when the head snaps off. They're quite flimsy so buy the big bag. Actually it's probably less hassle for you to replace the blind nuts with larger ones to use slightly heavier metric ones. They'll work much better. Amazingly, my plane never suffered any damage from belly sliding over the landing gear after they snap off the 4-40's, but I'm sure that could happen. (I have bigger wheels without pants too, the pants will surely puncture the wing when nylon bolts snap).

Tip for us tall grass landing field people: Drill two small holes through the lower rudder extensions and tail wheel anchor where they "mate". One hole above the other, right through all three parts. Holes just the right size allow a nice friction fit for round toothpicks, which can be sawed or clipped off flush. These flush "pegs" allow the rudder/tail wheel assembly to slide down into the fuselage normally. No glue means quick easy repairs and this holds the flimsy tail wheel assembly very firmly to prevent slop and ripping off the rudder in rough grass.

Cheers
Dr Z

Winnitwo

Dr Z
Thanks for your infos.
I'll keep the trick with the longer nylon bolts (for removing after they snapp off) in mind.

I don't understand the thing with the toothpicks. On my MP the stabilizer and the elevator are screwed onto the fuselage with thread rods, no clue. So the whole tail section is removable and seems to generate no problems in case of damage.
Is it different at your MP or did I just misunderstand something? Perhaps a foto could help.

Do you really want to repair your crashed fuselage? I guess you have to order a new one. I had about the same damage and it was clear that I can't fix it. I would never have found the correct position of the motorcarrier. Be aware that the motor carrier (I mean the balsa wooden block at the front side of the fuselage) is not exactly in line with the fuselage, it is a little bit inclined. Sounds crazy, but otherwise your MP would fly in circles. The motor axis needs a certain angle to the fuselage, it must not be in line.


have a nice week end

Winni

RZielin

My Feedback: (1)

RE: Tail wheel fix

Sorry for the confusing description. Here's a pic that's worth a thousand words. The top end of my tail wheel wire was working loose, flopping around and tearing up the rudder where it bends to the rear and enters the rudder. It's been totally solid since this fix.

I had enough slivers left of the motor box to cut three missing sides accurately. I confirmed angles from the new fuselage, which is still in plastic (why, tell me why do I do this?) The hardest part was removing the broken slivers and glue without destroying the three remaining sides. Almost cut off my finger with the Dremel using a small saw blade to remove epoxy. (You can just see the healing cut in the pic below). The box is ready to glue up, then I'll figure out how to reconnect it to the fuselage. She will live again! [>:]