old p47

My Feedback: (1)

I do not know. The struts the block and mounts are very sturdy I do not think you would gain much buying siera other than it being air. Horizon needs to get on it and do some QC.

speedbrake

I talked with Robart at Joe Nall. They claim to have a retract for this airframe, although they couldn't find a product number at the time. Also, I've read that Sierra also has a gear set for this plane. Give them a call for more information. I'm a bit discouraged reading about all the problems with this plane. I'm waiting for an elevator servo on mine....then will have all the necessary items to finish it.

Keith

sjhanc

My Feedback: (3)

I took a spare retract set for another P 51 I am building and held it up to the H 9 wing retract mount. I traced the Robart frame assembly on to the H 9 retract mount in the wing. It looked very close so I got out the Dremel and enlarged the rear of the H 9 retract mount towards the wing spars. After about 10 minutes work the Robart TF P 51 gear dropped in and the Existing (4) H 9 bolt holes lined up perfectly. I scrounged some metric bolts to fit the H 9 blind nuts and tightened it up. The ROBART strut is about 1 1/4 inch too short for the wheel well so that is a difference that would have to be solved. I am currently flying my TF GS P 51 B at 29 lbs. and the strength of its struts and frame assembly is at the upper limit of what the stock ROBART gear can handle. Maybe if ROBART made the frame assembly out of steel instead of aluminum and enlarged the strut diameter it would be an option for us to use.
My TF GS P 51 B is fitted with the electric ROBART retracts and they have been reliable in operation since they were installed in December, only once failing to go all the way into the wing when the climb out speed got too high. They extended ok for the landing and I only found that one strut had stalled while viewing some high resolution photos a friend took of the flight. My only beef about the ROBART retracts is the slow cycle speed-much slower than full scale P 51 aircraft. This fact and the problems other H 9 P 51 pilots have had with the EFLITE electric retracts led me to order the Pneumatic option from Horizon Hobbies. They are on backorder for two weeks but I don't plan to try to fly the H 9 plane for another 3 months unless the ROBARTS can't be delivered by then. I may have the get the Sierra gear instead.
A member of my club showed me his set of Eflite retracts and they look good except for the worm drive gear motor. In examining them I discover the motor is almost identical to a set of worm drive motors I bought a year ago to operate the inner gear doors on a mustang under construction. After mounting them and closing the doors the first time they worked fine- the second time I hit the retract switch to close the doors one of the worm drive motors smoked and failed and the wing was inverted with no airflow impeding operation so gravity was with the motor. If these motors can't handle the inner gear doors light weight how are they going to lift a pound of strut and wheel against air drag. My first TF GS P 15 B used ROBART air cylinders to close the doors and they worked every time.
The other thing to consider is the ROBART air control valve allows adjustable cycle speeds- I used two air valves, one for the doors and one for the gear and it worked every time with scale retract cycle speeds. The door valve and its servo were mounted in the belly scoop under the wing so only needed one air supply line. The modification I did to the one H 9 wing gear mount has not compromised the possible installation of the EFLITE retracts at a later time.

sjhanc

My Feedback: (3)

I had aircraft sheet metal experience during my US ARMY duty and have a friend with a metal brake so making my own steel frame assemblies is possible. Getting a longer strut from ROBART may be possible also. I would rather just buy a retract set from a manufacturer as the labor involved would be condiderable.

sjhanc

My Feedback: (3)

speedbrake,
When I couldn't find a set of Spectrum elevator servos in stock I went to the HITEC web site and found the HS-5245mg mini at 76 oz. torque is slightly thicker that the Spectrum servo recommended by Horizon. I ordered them from Amazon on a Sunday night and received them the next day. A little grinding inside the elevator servo mount and beveling the bottom back end corner of the servo case and it was tight but they fit. The price was much cheaper than the Spectrum servos and they are digital also.
When I was flying large sailplanes the flap and aileron wing servos were HITEC flat mount servos to get in the glider wing and I operated these planes at very high speeds- much faster than our P 51 models can reach and the control surfaces are larger than the little elevators in the P 51 models. I have owned several of these gliders for more than 15 years and they have hundreds of winch launches which are the greatest servo breaker a model will ever see. Winch launch line pressure exceeds 200 lbs. on the wing and the release at the top is the point where servos will get their gears stripped.

david57

I was able to get mine in the air this past Saturday, flew well! I used a da85 and a beila 23-10 4 blade prop which seemed to work really well . Gear worked well except for the gear doors which did not want to stay up .The doors work flawlessly on the ground?

BarracudaHockey

My Feedback: (11)

I'll bet that thing scrams with an 85

rgburrill

Remember when you presented your giant scale aircraft for the first time with pride in what youo had accomplished? Remember how long it took to build? Or has it been too long and have there been too many of these cheap pices of crap ARFs?

WI53072

I remember when I use to proof read all of my posts before I went ahead and posted them into an internet blog. Of course that was before the red squiggly lines appeared under misspelled words such as "youo" and the like that made it easy for me to check what I had written for typo's, etc...etc... I have come to realize that many people to this day don't comprehend what the red squiggly line means when they see them.

BarracudaHockey

My Feedback: (11)

Easy boys

speedbrake

I'll give Robart and Sierra a call and find out if they make retracts speciifically for this airframe, the cost, and if the current strut and wheel can be used. As for the inner doors, perhaps removing them would be a smart option.

Sjhanc: What battery did you use to power the Robart electric retracts on your TF GS P-51? And....did you use the Aux Battery or receiver Battery? I have one and it will run great via the Aux Battery but not the receiver battery....go figure.

old p47

My Feedback: (1)

SJ I think you did the right thing ordering the air retract option. Like I said the struts and blocks are very strong. As you stated the motors are very small. I was looking at a friends set of electron retracts for his new jet project an the motors are twice the size of the eflights. I be on the phone again today with horizon trying to get this sorted.

WI53072

Guys,

Has anyone gone electric yet with this bird? Would it even be possible?

Paul

CRG

My Feedback: (3)

Again: http://www.rcuniverse.com/forum/rc-w...l#post12013870

sjhanc

My Feedback: (3)

speedbrake,
I experimented with various voltages as the manufacturer says speed can be controlled with voltage but I only got a .5 second difference between 6 volts and 9 volts so I settled on an eneloop 5 cell 2000mah NiMH from batteriesamerica.com. The capacity used on a weekends flying is minimal and they don't self-discharge. The ROBART gear controller is mounted on top of the wing on Velcro and the battery is in the belly scoop on the bottom of the wing with the Benedini sound amp next to it. The gear switch is mounted on the right side of the belly scoop under the wing trailing edge and plugged in to the AUX port in the controller. I have no problems with this setup and have had the retracts fail to fully go up only once due to my allowing the plane to accelerate to a speed too high for the gear. They came down ok for landing. I don't use the retractable tail wheel option any more- too much trouble.
Measured current draw on these gear is so low it is near the lower limit an ammeter can show. It peaks at .3-.5 amps when the trunions reach the ends of the cam grooves in the housing blocks.

Shaun Evans

Hi,

Yep, I think I'm gonna save myself the hassle and throw this one up for sale.

sjhanc

My Feedback: (3)

speedbrake,
The inner doors are a necessary feature for scale competition-a class this plane is not qualified for. My first TF GS P 51 B was to be an attempt to get a plane into the higher levels of scale competition. I spent months working on these doors and the tail wheel retract and finally got it all working. When flying I found that the doors could not be seen operating in flight unless you did a really slow speed pass at 15-20 feet and timed the retract operation exactly right. This to me is not scale operation. I flew in a full scale P 51 B recently and was really interested in exactly how the pilot did everything and when he did it. The gear were retracted as soon as the wheels lifted and were done with indicator lights coming on during the steep climb necessary to limit airspeed to a safe gear cycle speed. The doors were closed during the first turn. The gear were lowered during the turn to the base leg and were down and locked before he leveled the wings on final approach. My two friends each took videos as long as the plane was in sight of the airport, they were standing several hundred feet apart during the tale off and landing. When I reviewed these videos I was disappointed that the only hint of retraction on any of the video was the main gear doors dropping down as the wheels broke ground and I could just see the left gear leg start up in one video as the turn out began at less than 50 feet altitude. I had counted seconds at liftoff and felt the 3 gears lock up at about 3 seconds later.
Going back to my "scale P 51 B" I was dismayed to find that this model was so far from true scale it would have no chance in scale competition, only stand off scale. My natural decision was to forgo the scale details that could not be seen when flying my models. I have seen lots of warbirds with all the equipment working more or less and my hat is off to any modeler who wants to do it all.
As for myself, I want to fly as much as possible and the spectators who see my planes fly always like what they see and never notice what is not there.
This H 9 P 51 is the closest to scale outline of any kit or ARF that is available. It is true that there are kits that can be scaled out but the detail is usually not on the plans-it is up to the builder to detail it. If an owner of this model wanted to make it look like scale he would have to discard a lot of the scale detail that comes with the plane and do it himself. It would not qualify as scale in the highest classes of scale competition having started as an ARF.
In my opinion it leads the pack in standoff scale and is worth the effort needed to get it in the air.

sjhanc

My Feedback: (3)

I am going to make a partial main door to close off the open space when the main gear are retracted. I am not going to change the hinging that is there in case I decide to make the doors operational later. I have already built a fixed tail wheel strut and mount that bolts into the tail wheel gear well using the stock retract mounting platform. The electric or air retractable tail wheel could be installed later. I have installed the air reservoir above the fuel tank mount and reinforced the bulkheads that support the upper nose sheeting as some pilots report sheeting damage done in this area while transporting the model in their vehicle. I load my planes upright into a cradle that fits the wing saddles so this reinforcement might not be necessary. But if you think about handling a thirty lbs.+ plane by supporting it in this area then the beefing might prevent hanger rash.

marksp

My Feedback: (9)

Anyone who attended Nall note if the gear in the demo "I Flew Big" Hangar 9 P-51 worked as designed? If so, any details on the setup?

Cheers

sjhanc

My Feedback: (3)

I haven't gotten in to the servo installation for the gear doors but I can tell you this- the servo to door linkage has to connect to the leading edge of the gear door and the servo arm and link to the door must be positioned so that the when the door is retracted fully the servo arm connection must be positioned so that the link and arm are in a straight line to each other at the servo(mechanical advantage). This gives the maximum power to hold the door closed against air flow trying to pull it open. When rigged this way the door cannot pull itself open when air loads affect it I have flown P 51 models with and without inner doors and there is a noticeable difference in top end performance at top speed, around 3-5mph. I fly B models which have better streamlining around the aft fuse so have a speed and climb advantage compared to D models.

david57

I used hitec 7955 servos on my gear doors . Can not pull them open with out breaking the door so am thinking the power controller for the retracts is dropping power on them . I am going to put the doors on a separate switch an operate them on a separate switch to see if that is the case.

david57

Servo operated air vent.

CRG

My Feedback: (3)

Stock E-flite retracts, but no inner gear doors. The builder had some personal matters come up right before the event and wasn't able to complete the doors or some other details like exhausts and decals.

Evolution 62GX for power with a JTEC compact inverted wraparound muffler, Falcon carbon 22x10.

Lifer

My Feedback: (1)

CRG,

Have you run the Evo 62GX yet and what is your opinion?

marksp

My Feedback: (9)

Right on!

Happy to hear the 62GX flew Nall!

Cheers