chris923

My Feedback: (53)

Good Info, Thanks!

MX240

My Feedback: (4)

One more reason I stick with air all these years.
Old fashion I know.....but still works.
A pre-user of Kraft electrics back when.
Jim

chris923

My Feedback: (53)

Current Project:

F-6D Photo Recon Mustang Flown by MOH Maj. Wm. Shomo

TF P-51, Glassed, painted with Rustoleum sliver, graphics by Bad Brad Graphics.
Will have: Robart elec retracts ( reworked), Bomb drop, led guns, RC ignitions G62
Projected maiden flight spring 2106.

Ralph White

Chris, Your current project looks great. What are you doing to the Robart Elec retracts when you mention they will be reworked?

Ralph

chris923

My Feedback: (53)

The Robart Mustang Electrics have a tendency to pivot at the linkage barrel causing the barrel to pop out of the cam blocks. The fix is to buy another set of housing blocks. trim the housing blocks to fit in the back side of the frame assembly. This will stabilize the outside cam block and prevent the linkage barrel from pivoting . Both cam blocks are now "caged" and stable.

http://cdn.shopify.com/s/files/1/033...-5ESP.PDF?3792

SWORDSN

My Feedback: (13)

Thanks for the info....It pays to secure ANY wires,cables, or air lines wires that are loose.When they pass through the fire wall I split a piece of fuel line and secure it with a tie wrap

Ralph White

Chris, Yes, I see what you are doing to kept the 2 cam blocks from rotating and causing the linkage barrel come out.

I had the same problem with my gear as the linkage barrel came completely out at the 2014 Mint Julep Scale meet in Kentucky. When the linkage barrel came out it let the electric gear motor to continue running during the entire flight (without my knowledge). This caused the control box to go bad on that gear and that gear would no longer function.

I sent the entire set of retracts and control box in to Down and Out. I talked to Ron Word at Down and Out and he told me they had a fix for the cam block rotation problem. When I got them back they had installed the fix in both main gear and replaced the control box with a new one with their name on it. At that time they were making the control boxes for Robart. You can see what they did in the photos below. They machined new cam blocks that had a connection bar between them that joined the cam blocks into one unit.

Looks to me like both methods will work fine. I have several flights on mine since the repair without any problem with the cam blocks or linkage barrel. Down and Locked charged me $50.00 to do the repair plus $18.00 for shipping. The costs are about the same for either method. The way Down and Locked did it might be an ounce or 2 lighter if that matters. Your method might be a little stronger against side loads on the gear structs.

Ralph

Ralph White

Swordsn, I like your idea of putting a piece of fuel tubing aroud any cables that pass thru a firewall. I'll be doing that from now on.

Ralph

chris923

My Feedback: (53)

Ralph,

The first set of electric's I had (still have) are a Down and Lock Conversion, they work great. However buying gear and have Down' do them was not cost effective.Since Robart did their conversion, I have purchased them.
That being said, Robart's conversion in this set are weak. This solution was easy to do and cheaper then sending them to Down and Lock. Down' product is better however.

Mpizpilot

My Feedback: (45)

My buddy and I maidened ours today. Great flying plane, was impressed how slow they'll go. Both have 55cc motors. He had a dead stick, but made a perfect landing and clipped the top of some dirt mounds that the farmer who owns the field decided to put at the approach end of the runway. No damage thankfully to either.

rossmick

Got her already to fly and had some problems starting the DA60. Once I figured out that the throttle servo was not really opening the carb, engine started on second flip. I did take the engine back to DA where they do their fantastic job of customer support. They checked over the entire engine, flushed the carb and installed some new reed valve supports. There have been some problems with the reeds breaking off and the engine swallowing them. Engine test stand ran perfect. Went for taxi check and had the right gear fold up on a slow speed turn. Sierra gear slipped on the axle, unfortunately you have to take the gear out to tighten it. It damaged the prop and wing tip, nothing major. Biggest problem is the fuselage was crushed forward of the canopy by my stand in the trailer even though I had used a foam swimming pool sleeve on the PC pipe. As I live in the country I have a mile of dirt road to travel and even at very slow speed the fuselage could not take the weight of the plane and the bumps. I am redesigning an new contoured stand so the pressure in not just on the top edge of the fuselage. Looks like at least a week before I can try for maiden flight as I must repair fuselage and figure out what slipped on the gear.

chris923

My Feedback: (53)

Ross,

None of these balsa fuse planes is very sturdy. I have had the same problem ( crushing the fuse). One the last two Mustangs, I doubled the balsa from inside the fuse. I glues balsa panels between the stringers. This has help with the crush problem. We as builders are adding so much to these air frames that the weight and bouncing in the vehicle creates havoc.

rossmick

Chris923

Well, been down with some crazy flu bug that has been going around, so maybe tomorrow I can get back out in the shop. Thanks for the info on the fuselage as I thought about running some hardwood stringers along side the top central stringer which broke. I will add the extra balsa as you suggested. I need to get it ready to show as our club has been invited to bring scale RC aircraft for a static display on May 15-17 at the Pima Air Museum . The plane does not have to fly just look good, so I will see what I can do. I have not figured out what slipped on the gear as I have not gotten it out of the wing, but will work on that while the glue sets on the fuselage fix.

sjhanc

My Feedback: (3)

rossmick,
Are you transporting it inverted? I also live on a rough dirt road- I have a pvc pipe cradle that supports the plane upright on the wing saddles and have had no damage to the plane in 15 years. When I get to the field I use a different cradle that supports it inverted for wing assembly.

rossmick

sjhanc

Yes I had the plane inverted so I could just attach the wing. Great idea - why didn't I think of it. I will see if I can incorporate a double position setup in the new cradle. I want to make an adjustable cradle so this idea should be interesting. If I figure it out I'll post some photos.

sjhanc

My Feedback: (3)

Building a cradle is a lot less work than repairing hanger rash. My transportation cradle is left strapped to the floor of my SUV. it probably wouldn't stop damage in a major traffic crash but I don't think it would be practical to build something that complex.

aghost

My Feedback: (13)

rossmick: I had a transport cradle (probably similar to sjhanc's) and an assembly cradle. This picture is of the two. The front portion of the assembly cradle can slide on the rails to fit different size planes and kind of collapse for storage.

rossmick

Aghost and sjhanc

Thanks guys for the input. It might be wishful thinking, but I wonder if I can make an adjustable cradle that can handle the low flat set on the wing saddles and convert to an inverted operation as well. To make it more complicated it should be adjustable for different aircraft. Should be an interesting project with the philosophy of KISS. I really don't have room for two cradles for each aircraft I own. This will take some outside the box thinking as my current trailer is small and the stated requirements are complex. I don't think at this time that pvc will be my material of choice due to the adjustability of the cradle .

Aghost - thanks for the photo, it is very helpful, and the inverted one sure looks like the one I have now.

sjhanc

My Feedback: (3)

The inverted cradle I use now is made of 1/4 inch plywood using cabinet door hinges for folding action. When not in use it folds flat and fits in about a 3 in. space. I got the idea from an RC magazine years ago. the cradle part is cut a little larger than the fuse and lined with pipe insulation from plumbing supply. It will hold the fuse upright or inverted. It is too tall for safe transport though. It needs to be tall enough to clear the fin.

rossmick

Here is my design for a convertible/modifiable cradle. Concept is to have removable plates to do different orientations, upright/inverted. Material are; 1/8"x2"x2" alum angle, 1" MDF blocks, 1/4" hardboard, swimming pool tubes, I would have used 1/16" angle but ACE was out of stock, so I swallowed hard and bought the 1/8".

Photo 1 - 2; both sets of removable plates installed . Taller plates for inverted fuselage, I will cut in the profiles for the fuselage and line them with foam tubing tomorrow. The inverted plates will never be used to transport the aircraft only to hold the plane while the wing is installed and the gear tested.
Photo 3 - upright plates only, which could be removed for spacing if required.
Photo 4 - Construction of MDF blocks with 1/4" spacing.

This plate arrangement will require very little storage and making the plates is pretty straight forward when the next aircraft comes along. I did paste wax the plates and will drill two 1" holes in the plates to allow for a finger grip to pull them out. The MDF is end screwed and I hardened the screw holes with CA. NOTE. be careful and don't drill the pilot holes too small in the MDF or you will get a split when you put in the screw. The locations for the MDF blocks can be moved by drilling a different set of holes in the alum angle where needed to allow for the adjustable side of the design.

sjhanc

My Feedback: (3)

rossmick,
That looks like a good design. After reading a couple of reports of transport damage, I took a good look at the structure of my new 60cc Hanger Nine P 51 D. I removed the tank floor and built reinforcement bulkheads for the top sheeted structure to distribute the loads down into the fuse sides. Even though the top sheeting is like the TF GS plane, the thin bulkhead and stringer design didn't look like it could take even normal handling loads. The TF plane is a box with heavier framing and I never had any issues with normal handling. The H-9 plane is a stressed skin structure that's great for light weight and normal air pressures but can easily damaged by rough handling.
I weighed the H-9 fuse and it is a little more than 3 lbs. compared to the empty TF fuse at over 7 lbs. Even an unfinished TF fuse I have (no top and bottom sheeting and no tail feathers) weighs over 4 lbs. The main draw back to the H-9 fuse is the stab mounted elevator servos putting 2.2 oz. that far back in the plane. As you know, a long nose P 51 needs approximately 8-10 oz. in the nose to balance each excess oz. in the tail. Add the steel hinge wires for the control surfaces and a heavy tail wheel retract and the need for nose weight goes way up. Some H-9 pilots reported having to add 1-2 lbs. to the nose for balance. I would rather add a larger engine and propeller than lead.

aghost

My Feedback: (13)

rossmick, good looking cradles. Regarding the potential nose sheeting damage on the P-51. The front portion of my assembly stand actually had a 3" x 3" pvc square covered with thick foam, not just a single bar/swimming pool tube. Its not really obvious in the photo in my earlier post.

mark IX

My Feedback: (9)

Sjhanc, have you considered the Suppo 7035-8 motor? I am told that it does have a 3rd bearing supporting the rear of the rotating can, however, I have not been able to find any pictures showing that area.

Some motor specs: 10-12s, 190kV, 6660W max, 10mm shaft dia., max current 150A, Prop sizes - 26" on 10s, 24" on 12s


Mark

sjhanc

My Feedback: (3)

I will make my choice from the motors that I can find all the data that I need to make an informed choice. My initial choice of the R 65 motor was based on a desire to get a plane going economically, at that time I was unaware of the design differences of the various brands. I had also bought large Hacker motors for high powered sailplanes and had experienced expensive failures in motors, ESCs, and batteries. I got good enough results from the RimFire motors to see that large warbirds could be done. Now I know a lot more about this new (to me) part of this hobby I can proceed with more confidence.
The details to stress are motor cooling, separate ESC cooling, motor bearing design, and parallel motor packs for better battery reliability. High C ratings on motor packs is not necessary with parallel cells.
When LIPOs were first introduced parallel cell packs were the only way to go. With the development of high C cells the emphasis shifted to packs with high cell counts and C ratings but these packs are much more expensive and are produced in limited runs. Trying to find an identical pack to replace a puffed cell is difficult.
I am currently assembling the 60 cc H 9 P 51 but will use my old reliable gas motor until I am familiar with this plane's characteristic- then buy another for conversion to electric power.

sjhanc

My Feedback: (3)

This last Saturday I was invited to demonstrate my TF electric P 51 B to a club an hours drive north at their annual club picnic. There were as many wives and kids there as pilots and the kids seemed to be impressed with the large size, real airplane engine sounds and high performance speed and maneuvers my plane executed. I had no heating issues on a 90f+ day and other than a power wire disconnect on the sound amp, no other problems.
Some high resolution pictures later showed that during a 90 degree banked turn there was considerable wrinkling of the top wing skin. A turn like that can exceed 9 Gs so I will dial back the up elevator in maneuvers in the future. The stress may have been caused by turbulence off of the nearby tree line behind me.
The applause and the sounds the kids made during the flight made it a fun day.