RE: Pitts Pythons in Customs now  
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RE: Pitts Pythons in Customs now - 5/10/2007 4:13:30 AM   
V1 RO T8


 

Posts: 54
Joined: 10/7/2004
From: Copley, OH, USA
Status: offline 		I crashed mine two days ago, and in similar manner.
Was doing touch and goes in mostly calm conditions, with an occasional gust of 10KTS, or so. Approaches were pretty much directly into the wind.
Just starting the round-out at about 2 feet, and it suddenly nose dived. Not sure why. I've never had anything like it happen in all my RC expereince.
Ripped the right main gear off, and trashed the cowl and one wheel pant. No other damage.
Luckily did not bend the muffler, which had buried both pipes in the dirt.
Plane flipped on its back, but the tail did not break. I had strengthened it as a result of a previous landing flip damage resulting from catching a wheel in a rabbit hole.
After consultation with John at Aerotech-rc, we suspect a too-forward CG. I am using 3" standoffs, and have 4 lithium ion batteries in the motor box.
Three landing flips, severe knife edge coupling, and too much forward stick required during inverted--all add up to likely nose-heavy condition.
After all repairs done, I'll move the batteries rearward, and really hone in on the correct CG.
John says the proper way to balance this plane is to: transfer a line under the top wing center section, at the recommended CG. Hold the completely assembled aircraft under the top wing center section at that line. DO NOT attempt to balance at the wing tips. Can overstress the wings, and accuracy can suffer due to difficulty of transferring CG location out to the wing tips.
This is my first Aerotech-rc plane, and I am very pleased with the customer service of the company. John got the parts out to me right away, and was helpful during phone support about the CG issue.


(in reply to alpapilot)
       Post #: 276

RE: Pitts Pythons in Customs now - 5/10/2007 5:24:02 AM   
alpapilot


 

Posts: 144
Joined: 1/8/2005
From: Newnan, GA, USA
Status: offline 		Yeah, John is looking into the cost of parts for replacement. Unfortunately, I think I need a whole new fuse, cowl, and scoop. Winds were probably around 10G20 right down the runway. In the flare it starting rocking really badly so I tried to go around. I guess the high AOA and left turning tendencies started the plane to the left (towards the flight line) so I added right rudder. Well, the extra rudder combined with a gust flipped the plane over and it did a half cart-wheel. The internal support structure for the lower wing is badly torn up now.

Funny thing that you mentioned knife-edge coupling as that is what I was practicing before my crash. With 2.5 inch standoffs, aluminum spinner, and lipos it balanced about a half inch behind the recommended CG. The plane did a perfect KE in both directions with absolutly no need for any coupling. Rolled it on the 90, added a tad of up rudder, a little over half throttle and it tracked straight and true. Too bad about the landing though.

(in reply to V1 RO T8)
       Post #: 277

RE: Pitts Pythons in Customs now - 5/10/2007 3:44:28 PM   
V1 RO T8


 

Posts: 54
Joined: 10/7/2004
From: Copley, OH, USA
Status: offline 		I have noted the original mark that we used for balancing is mistakenly 1" forward of the proper location--plus we held it up by the wingtips, which John said is improper technique. So, we had a "way-forward" CG!
I will use 7" after the rebuild(doesn't it stink to have down time in the flying season?!?). That is at the aft end of the recommended CG range, which according to the instructions, is 6.5"-7".
Are you saying that yours was at 7.5"? And with that CG, it flew nice?
When I do the test fly after rebuild, I'll remove all mixes, set throws to recommended, and start the trimming/mixing process all over again.



(in reply to alpapilot)
       Post #: 278

RE: Pitts Pythons in Customs now - 5/10/2007 3:51:22 PM   
bonedaddy41



Posts: 425
Joined: 6/6/2003
From: Denton, TX, USA
Status: offline
quote:

ORIGINAL: V1 RO T8
... plus we held it up by the wingtips, which John said is improper technique. ....

John would be the one to know. I balanced mine using both methods ... center section and wingtips ... and had the same results with both 6.5-7". If John says don't use the wingtip method ... I will stick to the center section from now on The flight characteristics of mine lead me to believe that the balance is almost perfect for all around flying. Inverted flight needs just a touch of down elevator ... and I mean just a small touch. Knife edge has very slight coupling.

< Message edited by bonedaddy41 -- 5/10/2007 3:56:59 PM >

_____________________________

Don't knock on Death's door. Instead, ring the bell and run. He hates that.

(in reply to V1 RO T8)
       Post #: 279

RE: Pitts Pythons in Customs now - 5/10/2007 11:48:32 PM   
V1 RO T8


 

Posts: 54
Joined: 10/7/2004
From: Copley, OH, USA
Status: offline 		OK, thanks--I appreciate the input.
Looking forward to a much better flying airplane from now on.
Take care.

(in reply to bonedaddy41)
       Post #: 280

RE: Pitts Pythons in Customs now - 5/11/2007 12:09:00 AM   
alpapilot


 

Posts: 144
Joined: 1/8/2005
From: Newnan, GA, USA
Status: offline 		I was at 6.5 or 7. Really can't remember. Also, I just don't think a half inch would make that huge a difference.

(in reply to V1 RO T8)
       Post #: 281

RE: Pitts Pythons in Customs now - 5/11/2007 1:51:56 AM   
V1 RO T8


 

Posts: 54
Joined: 10/7/2004
From: Copley, OH, USA
Status: offline 		Thanks, A.P.

(in reply to alpapilot)
       Post #: 282

RE: Pitts Pythons in Customs now - 5/12/2007 6:30:38 PM   
edgeman55-RCU


 

Posts: 580
Joined: 8/24/2002
From: Dayton, NV, USA
Status: offline
quote:

ORIGINAL: alpapilot

I was at 6.5 or 7. Really can't remember. Also, I just don't think a half inch would make that huge a difference.


This is 6.5-7.0 inches from the leading edge of the center section? Just want to be sure as I will be getting close to CG time if real life stops getting in the way.Thanks.

(in reply to alpapilot)
       Post #: 283

RE: Pitts Pythons in Customs now - 5/13/2007 12:20:21 AM   
alpapilot


 

Posts: 144
Joined: 1/8/2005
From: Newnan, GA, USA
Status: offline
quote:

ORIGINAL: edgeman55-RCU


quote:

ORIGINAL: alpapilot

I was at 6.5 or 7. Really can't remember. Also, I just don't think a half inch would make that huge a difference.


This is 6.5-7.0 inches from the leading edge of the center section? Just want to be sure as I will be getting close to CG time if real life stops getting in the way.Thanks.


Oh God no! Leading edge from the first fuse former like the instructions say. If you go from the leading edge of the top wing subtract an inch. Other wise you will be extremely tail heavy.

(in reply to edgeman55-RCU)
       Post #: 284

RE: Pitts Pythons in Customs now - 5/23/2007 6:10:09 AM   
lear31A


 

Posts: 867
Joined: 8/25/2003
From: Hattiesburg, MS, USA
Status: offline 		I ordered one today for this years flying season! I cant wait. Thanks for everyones input on this.

_____________________________

Will fly for coffee

(in reply to alpapilot)
       Post #: 285

RE: Pitts Pythons in Customs now - 5/27/2007 11:10:56 PM   
LowKey3D



Posts: 244
Joined: 5/22/2002
From: Orlando, FL, USA
Status: offline 		Hey bonedaddy

Do you have a picture of your 58 mounted on the Python. I'd like to get a visual before I mount mine..
I'm just getting around to my build. Joe Nall pushed everything back and I lost my 50cc edge
so now I have nothing aerobatic to fly so its full ahead on this project..

Los

(in reply to bonedaddy41)
       Post #: 286

RE: Pitts Pythons in Customs now - 5/31/2007 5:57:54 AM   
bonedaddy41



Posts: 425
Joined: 6/6/2003
From: Denton, TX, USA
Status: offline
quote:

ORIGINAL: los08
Hey bonedaddy

Do you have a picture of your 58 mounted on the Python. I'd like to get a visual before I mount mine..
I'm just getting around to my build. Joe Nall pushed everything back and I lost my 50cc edge
so now I have nothing aerobatic to fly so its full ahead on this project..

Los

No, sorry - I don't. I didn't even think about taking pictures before I put the cowl on. I will snap a few the next time I take the cowl off.

I used 1/4"-20x2" bolts with blindnuts and 1" nylon spacers (with flat washers on each end) I picked up at Lowes for the standoffs. I cut a fairly large hole in the firewall for carb clearance. That is pretty much the olny differences from any other engine mount. I mounted my ignition module on the left side of the engine box (facing the front of the engine) and mounted my 2 cell 2800mah lithium ions on top of the engine box. I mounted my cowl flush with #2 former (the one the canopy dowels fit into). This setup gives me about 1/4" to 3/8" prop to cowl clearance. I had some old JR537s laying around that I used for the choke and throttle in the locations provided. I am running a 24oz fuel tank right on the CG.

Sorry to hear you lost your Edge. I am really enjoying the Python plus have an 86" composite Sukhoi in the works as my first monoplane in 3 years.

< Message edited by bonedaddy41 -- 5/31/2007 6:06:33 AM >

_____________________________

Don't knock on Death's door. Instead, ring the bell and run. He hates that.

(in reply to LowKey3D)
       Post #: 287

RE: Pitts Pythons in Customs now - 6/1/2007 1:15:18 AM   
LowKey3D



Posts: 244
Joined: 5/22/2002
From: Orlando, FL, USA
Status: offline 		Bonedaddy

No need for pictures your discription is right on. I can see from my drill pattern where a washer or blind nut will be
a tight fit in the upper right corner of the firewall because of the triangle stock. I won't know until I actually drill and
try to mount the engine.. I already have a idea on how to deal with it if it's a issue. I guess I'll try my first cowl ring
to mount the cowl...

(in reply to bonedaddy41)
       Post #: 288

RE: Pitts Pythons in Customs now - 6/1/2007 4:17:19 AM   
bonedaddy41



Posts: 425
Joined: 6/6/2003
From: Denton, TX, USA
Status: offline 		Yep. If memory serves right, due to the wide stance of the 58's bolt pattern, I had to recess all 4 blindnuts in the corner triangle stock at least a small amount ... and I believe I had to grind flats on the lower two for box bottom clearance .... but I have mounted so many this way, my memory may be merging them all together

This was my first cowl ring also. I used some of the extra ply that John used for shipping protection I got a general guestimate of the cowl diameter 1" in ... and added about an 1/8" for safety. I then hand fit the ring while shrinking it with my belt sander. It worked perfect. With the cowl fitting the fuse so tight, the cowl ring is really just to make it stay where you want it. I doubt that it will ever vibrate enough to crack a glue joint on the ring.

_____________________________

Don't knock on Death's door. Instead, ring the bell and run. He hates that.

(in reply to LowKey3D)
       Post #: 289

RE: Pitts Pythons in Customs now - 6/16/2007 5:38:43 AM   
lear31A


 

Posts: 867
Joined: 8/25/2003
From: Hattiesburg, MS, USA
Status: offline 		I flew mine today and I love it! I apreciate all the info you guys have given! Take Care

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_____________________________

Will fly for coffee

(in reply to bonedaddy41)