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Jul 27, 2014, 05:27 PM
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CMP 72" C-160 Transall information


I am in the process of building a CMP 72" C-160, the Nitro version with a conversion to electric. I have read all of blogs back to 2004 and viewed all of the videos that are still available. It appears that the plane as built by CMP has changed over the years to correct a number of problems. My questions are focused on more recent experience of the members. I started by building two of the CMP 57" both of which are now in the county landfill due to very bad stall problems. My experience with those versions lead me to believe that a wing load of 38oz/ft is just too high making control very demanding. The 72" version has a load of around 24oz/ft which seems to me to be more reasonable and judging from the previous blog postings a better flier.

Are there any members with recent experience (EP or Nitro) that would care to pass that information along? It would be much appreciated.

Jim
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Jul 29, 2014, 09:03 PM
pǝʇɹǝʌuᴉ sɐʍ I ǝsnɐɔǝq
LowlyElevated's Avatar
Quote:
Originally Posted by jimschroed
I am in the process of building a CMP 72" C-160, the Nitro version with a conversion to electric. I have read all of blogs back to 2004 and viewed all of the videos that are still available. It appears that the plane as built by CMP has changed over the years to correct a number of problems. My questions are focused on more recent experience of the members. I started by building two of the CMP 57" both of which are now in the county landfill due to very bad stall problems. My experience with those versions lead me to believe that a wing load of 38oz/ft is just too high making control very demanding. The 72" version has a load of around 24oz/ft which seems to me to be more reasonable and judging from the previous blog postings a better flier.

Are there any members with recent experience (EP or Nitro) that would care to pass that information along? It would be much appreciated.

Jim
On the 52" version, fly it like you stole it. It doesn't like to go slow.
Jul 29, 2014, 11:40 PM
Up-Out-&-Gone
demondriver's Avatar
I wanna see some C-160 build pics soon!
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Aug 02, 2014, 03:11 PM
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C-160 update.


This is not a build log but I am happy to pass information that may help others if they are building a C-160 from CMP. I was very happy with the finish and condition of the wings, fuselage and tail feathers. Aligning them became the first challenge. I mounted two blocks to the landing gear superstructure and used that as my reference for aligning the wing from side to side. After measuring the fuselage using a laser I decided that the painted strip that separates the white top from the gray bottom was a good reference for the fuselage and used that to measure the angle of incidence which proved to be just over 2 degrees.

I used fiberglass and epoxy to build up the wing bed and ground out excess material to position the wing on the vertical axis. Once the wing position was established and anchored in place I then started on the horizontal and vertical stabilizers. The horizontal dipped about three degrees to the port side and had an additional two degrees of incidence relative to the wing. Some grinding and filing removed the material to properly position the stabilizer. I reduced the incidence angle to zero degrees relative to the wing.

Both the stabilizers will require some filling, the cutouts provided are more than needed by a considerable amount. I am using a couple G15's to power the bird, I used G10's on the 57" and that was more than what was needed to get it airborne. I will add about 200uf of capacitance to the power leads to help deal with any switching transients. Battery size is still to be determined based on what is in my current inventory.

If anyone else out there is involved with this particular aircraft please pass along your experience.

Jim

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Description: Comparison of the CMP C-160 57" versus the 72".

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Description: I am using two Turnigy G15's with Plush 60 amp ESC's mounted in the nacelles.

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Description: Some of the bedding required to reposition the wing.

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Description: I used a laser to align the control surfaces with respect to each other, here I am gluing and aligning the vertical stabilizer.

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Description: As you can see the fuselage cutouts are approximations and some filling will be needed.
Aug 06, 2014, 02:25 PM
An itch?. Scratch build.
eflightray's Avatar
The C-160 takes me back, my second twin was a scratch built Transall, (first was a Catalina).

It's first flight was way back in 1991, brushed motors, belt drives, and Nicad packs.

Good look with the build Jim.

Oh!, that last picture isn't of a crash, it's how I designed it to disassemble to fit a small car.
Last edited by eflightray; Aug 06, 2014 at 02:28 PM. Reason: edit to correct wrong date
Aug 06, 2014, 06:57 PM
Registered User
Thread OP

Nice looking Transall


Very nicely done. I am struggling with the build on this one. I am afraid this bird is going to weigh in at ten pounds. This is going to up the wing loading and create other problems. I am arriving at the conclusion that the available kits of the C-160 are not very good flyers.

Jim
Aug 07, 2014, 05:03 AM
An itch?. Scratch build.
eflightray's Avatar
Quote:
Originally Posted by jimschroed
Very nicely done. I am struggling with the build on this one. I am afraid this bird is going to weigh in at ten pounds. This is going to up the wing loading and create other problems. I am arriving at the conclusion that the available kits of the C-160 are not very good flyers.

Jim
Ouch!.

My balsa scratch built was 5Lbs - 7oz 'dry', and 7Lbs - 3oz with 14 Nicads, (two 7 cell packs = 1Lb -12oz ).
Aug 09, 2014, 07:21 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by eflightray
Ouch!.

My balsa scratch built was 5Lbs - 7oz 'dry', and 7Lbs - 3oz with 14 Nicads, (two 7 cell packs = 1Lb -12oz ).
5 lbs is not that heavy at all Eftray. . . What was the wingspan?
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Aug 10, 2014, 04:44 AM
An itch?. Scratch build.
eflightray's Avatar
Quote:
Originally Posted by demondriver
5 lbs is not that heavy at all Eftray. . . What was the wingspan?
She was 81" span.

The 'Ouch!' point I was making was the difference between my model and the expected weight of Jim's model at 10Lbs and 72" span.
Aug 10, 2014, 02:37 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by eflightray
She was 81" span.

The 'Ouch!' point I was making was the difference between my model and the expected weight of Jim's model at 10Lbs and 72" span.
A plane with an 81 inch wingspan with a 5lb weight is very impressive Sir! what materials was she build of?
Latest blog entry: RC 737 Max 7 Maiden flight!
Aug 20, 2014, 06:08 PM
Registered User
I just ordered this arf from ScaleFlying in WA. $140 shipped is a nice head start. I welcome any tips and advice for electric power and building. How hard would it be to add flaps?

I love the photos I am seeing so far.
Regards,
Jeff
Sep 03, 2014, 04:42 PM
Registered User
Thread OP

C-160 Update


I thought I would pass along the final configuration information on the C-160 Transall. I am ready for a maiden flight later this week. As mentioned in a previous post the wing and the horizontal stab required some work to arrive at decent angle on incidence. I finalized the wing at 2.0 degree and the horizontal is at zero relative to the wing.

I am running two 3300 mah batteries in parallel with power to the motors provided by two Turnigy Plush 60A ESC's. The motors are Turnigy G15's with MAS 10x7x3 props that are counter rotating. The CG is set at 75mm.

If this version of the C-160 flies but shows instability then I am seriously considering redesigning the wing. I would retain the center section with the nacelles and replace the end pieces with a Clark Y foil, add about 2 or so inches and eliminate the rear taper. This in an attempt to reduce the wing loading. The current weight ready to fly is 9 lbs 6 oz. This is just a heavy bird.

Jim
Sep 04, 2014, 09:58 AM
An itch?. Scratch build.
eflightray's Avatar
Hope she flies well, Jim
Sep 04, 2014, 11:46 AM
Registered User
Jim, best of luck! I have a C-160 kit I am going to start building in the coming weeks and looking at yours for guidance.
Jeff
Sep 05, 2014, 04:15 PM
Registered User
Thread OP

Maiden flight a success.


I managed a successful test flight this morning. All in all the C-160 flies better than I expected. The bird did not exhibit any bad habits and the landing speed was somewhat slower than I expected. I think with some trimming positive stability should be at hand. I started with the cg at 75mm I plan to move that to 80 for the next flight.

As posted above I am running two 3300mah batteries in parallel for a total capacity of 6600mah. The test flight lasted a little over four minutes and the batteries required about 650mah each to recharge for a total usage of 1300 mah. To reduce the weight I could go to a smaller battery pack and probably shave off 6-8 oz. The current capacity will give me about ten minutes of flight time, more than I would use or need.

The 72" Transall is a better plane than the 57", not sure why both have high wing loading but this one feels better. Part of this may be the care I put into the assembly and measurements after sending two of the 57" versions to the county landfill. Hope this helps other Transall builders and pilots, it is a nice looking plane.

Jim


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