curtusua-RCU

My Feedback: (91)

Hi Nick...

Thanks for the tips!

I actually hadn't added the plastic shims but just now experimented with two #6 washers under each of the retract mount's outer mounting holes and it now seats nice and flush with the wing.

What size Robart wheels are you using? I was thinking of ordering a set of 5" aluminum wheels myself.

Here's a couple of pics:

njmheli

HI Curt.

Glad it looks to be working now for you.................if you go to post # 395 in this thread,you will see my wheels and the doors etc..........I'm using the 5" 8 spoke robarts...Check out the photos.Just make sure that your wheels can rotate in the "well",they don't have to spin freely,just enough so as the retract is not trying to push them out of the top of the wing !!!!

Any problems.....mail me !!! Here to help if I can !!!

Cheers.............Nick (UK).

Doug Andre

Guys,

Some Robart Electric retract FYI we learned the hard way! 

Be sure to use heavy duty extensions to power all three retract motors. We ultimately used JR heavy duty.    The ultra-light wire gauge in standard extensions will not properly convey the current and allow the Amp-out cycle to operate properly. The legs could reach a point of heavy load and stall without cutting power to the motor and possibly ruin the tiny motor after an extended period. (ask me why I know about this)  The retracts should be driven separately with a 2-cell LiPo for a nice 8 Volt plus supply of power.  Be careful of polarity when plugging auxiliary power into the control box.  A mistake will destroy the circuit instantly.  We killed one this way and Robart kindly replaced the unit for free.
Also, the provided plastic gear doors for the 30 cc Jug are not sufficiently strong for the duty expected of them. Out of the four ships flying at our club two lost doors while retracted. The screws simply ripped through the plastic material. the other two models never had their doors installed so that is 100% failure.  The thrust coming back from  a 20 inch prop folds the doors almost double. We ended up making new doors out of Aluminum sheet from K&S.  The Aluminum holds a nice airfoil shape to match the wing when retracted.  None of us ever installed inner gear doors.  I have about 30 flights on mine with great success.

Good Luck,

Doug

njmheli

Hi Doug.

Wow......thanks for the info / update........I'm using LADO retracts ( I have the D & L retracts in my T/F SW,and have always used a seperate power supply and HD extensions ),The LADO retracts have HD wire and as usual,they are all connected using the HD extensions and the seperate power supply.

I'm pretty sure that there is a "warning" from D & L / Robart with regard to polarity........there was for my SW set up,together with a "caution" about too higher volts on the earlier "control-box",but I had that changed by D & L to the newer version that accepts the Lipo input.

On the door issue ( as I and I guess a few more on this thread have not yet flown our birds ),did you guys use a washer under the door bolts and also did you use the "stiffner" in the door construction...?I have "built up main doors and inner doors and I think that these are pretty strong,takes alot to "form" them when finished constructed and with all the extra stringers in the constuction........appear to be good and stiff ???

Hope that mine hold together.........???

Thanks again for the up-date...........Interesting that John R has never spoken or mentioned any possible "gear-door" problems.....mmmmmmmm []

Cheers..............Nick (UK).

John Redman

My Feedback: (8)

As Nick stated the included plywood stiffner is required to keep the main gear doors together. I did not use them on my first set and one ripped off in no time. Since the stiffner has been installed I have not had a problem.

As for the retracts, I only use heavy gauge extensions on any model that either has a 12 inch long extension or an engine of more than 20cc's. Never tried the smaller light weight extensions but can imagine just what you have stated. I use (2) 2000 mah Li-Po's for the power safe receiver and power the retracts through the receiver without any issues.

Doug Andre

Nick,

Yes the warnings are printed on the Robart control box and the retract instructions.  I did not take them seriously enough though.
Our gear doors were assembled and installed exactly as specified in the H-9 manual.  We did use washers.   The door gets folded back by the airstream and the plastic material fatigues and tears at the drilled bolt hole locations.  I never expected this to happen.  I assure you, your stock door will fail.  My partner lost his first door on the fourth flight and mine folded and failed after about six flights.  We spent a couple of hours each making Aluminum doors and have been rewarded with bullet proof durability.  The weight is simply not an issue.  Our EP ships are already pushing 22lbs.

Regards,

Doug

njmheli

Hi Doug.

OK..............thanks for the "additional info",I have already given this some thought and I think I have come up with a simple solution to using the stock door set up and for the "built-up"doors........now having heard where yours failed.Interesting to know that it bent back and failed around the holes..........

I agree..............the Ali doors are 100% bullet proof !!!

Using the stiffners provided ( well,mine were soaked in oil from the factory !!! so they went straight into the bin !!! ).......I think you will run into the "height" problems of getting the door flush with the wing skin on the retract ..........I used some different ply,but only part way down as otherwise the oleo will "bang" into it on a good full compression of the strut....due to the "welded" "lump" that Robart put on the end !!!

I will do the mod over the weeked and put some photo's up..............if what I think will work out for guy's using the "stock door",built up or un-built up................

Will be using a bit "coke" can,plastic strip,epoxy............and a bit of luck and one assumes that the gear door doesn't have to come off all the time for any form of maintenance !!!

Thanks again Doug.

Cheers...............Nick (UK).

Ron101

My Feedback: (22)

Mine is ready for maiden

The doors seem very filmsy to me also, but I heated mine to get a good bend to close all the way. Were the doors that ripped off bent at all? mine were straight to start and I could tell right away if they were flat air would rip them off if it got under them.... but I'm hoping with a bend and tight fit the air will push them closed and not rip them off.

I was also thinking about making my own doors..... I think I may just remove them for the first flight and make a set up next week

njmheli

Hi "Ron"

I think it is probably a combination of material flexing and fitting...........if you think of the door,no matter if it is flat or "profiled",in an air stream it will act like a wing.........producing lift in one direction or another + plus drag !!! a curved profile probably more so like a wing,flat profile would depend more on the relative air flow over it.........bit like driving you car and holding you hand flat into the wind...change the angle of you hand and it goes up or down.

I think it is a question of material strength against speed of airflow.........as Doug says,ali 100% perfect........it has the strength for its shape / weight of the door.

( Full-size limit the speed range with gear and or flaps deployed,the ones that I used to fly...all marked in a white "arc" on the ASI )

For the "stock" set up,I guess it's just making the material stronger in the areas that have caused the "flexing"..........plus don't fly at high speeds with ill fitting or weak doors !!!

Good luck with your maiden...........and doors !!!

Let us know how she goes..........

Cheers.................Nick (UK).

Doug Andre

Ron,

We gently curved our doors for a good fit into the wells. We matched the airfoil shape.    I gave a lot of thought to the material failure and first wondered if a small amount of Loctite could have affected the strength of the plastic where it may have wicked onto the door.    I used the blue version which was supposed to be plastic safe.    There was no evidence of Loctite anywhere on the door.    Could I have overtightened the screws crushing the door at the attachment point?   The door on my ship was folded with as much force as I could apply with my hand. I had no idea that the airstream could do so much damage.   We just went straight to the Aluminum since it would hold the airfoil shape,could not be crushed by the mounting bolts and would not ever be affected by any type of thread locker.   The Aluminum took paint and rivet detail very well so I am satisfied.

Doug

curtusua-RCU

My Feedback: (91)

Hi Doug...

I think I will follow your suggestion and make new doors out of aluminum. It seems the way to go for durability.

Can you give some more detail about their construction? What is the thickness of the sheet aluminum you used? How did you attach the doors? Etc. Any chance you could snap a photo or two?

many thanks...

Curt

Ron101

My Feedback: (22)

yep I'm with you guys..
I took my door off and will make a new set after the maiden

Don't want an issue with the doors messing something up, not worth it

Doug Andre

Ron,

I used .032 Aluminum sheets,  (K&S Stock Number 16256)  From Horizon hobby,  6" X 12".   Use a flat stock gear door as a pattern. Scribe a line around the pattern and cut the sheets with a  fine metal cutting blade.  Dress up the rough edges with 250 sandpaper.  Trial fit the door into the well without the retract in place.  Install the retract and then gently curve the door  by hand to match the airfoil of the wing. Be sure that the retract leg just touches the door at the attachment point.  We used the HANP47 main retracts from Robart and the door simply bolts to the leg with two 4-40 button head bolts (no washer).  Fine adjustments can be made after the retract is operable.  I added some rivet detail to the exterior of the door by drilling with a 1/16th bit, tiny holes going in only a couple of thousandths to suggest flush rivets.  Paint the door to match the Ultracoat Aluminum because real Aluminum looks nothing like that Ultracoat color.  Paint the inside with your choice of Zinc Chromate green.   This is actually all very simple and fun to do.  On a smaller ship we might be concerned about adding weight but not so here.

I will try to post some pictures when I can

Regards,

Doug

Doug Andre

curtusua-RCU

My Feedback: (91)

Hi Doug...

Thanks for the info and photos. Do you still just use the two 4-40 machine screws to mount the door, or do you have other attachment points or reinforcement? Do you still need to add the stiffiner strip?

Thanks again...

Curt

RoysterDW

Whats the most popular engine used for this bird? Will a DLE35 pull it along?

Doug Andre

Curt,

The Aluminum doors are very strong and need no stiffeners.  The  Robart legs are threaded for two 4-40 bolts.  No other mounts are employed. 

Regards,

Doug

curtusua-RCU

My Feedback: (91)

Great! Thanks, Doug...

Curt

DHC6

My Feedback: (6)

Hey guys I was wondering if some one could tell me the diameter and width of the stock wheels please.

SU-31 flyer

The wheels are 5.125
THis is the largest and is the scale size for a 1/6 scale P-47.

DHC6

My Feedback: (6)

Thanks SU-31, I just wanted to make sure they will fit on my FT P47, they are much better looking then the ones that came with the aircraft and are not nearly as expensive as other scale sets.

SU-31 flyer

That size is from an E-Mail from John Redman of Horizon. I had asked the same question.

Doug Andre

SU-31,

We were considering ordering the Robart Aluminum 5" scale wheels.  The H-9 provided wheels look much thinner in cross section than the Robart.  Does anyone know if these will fit into the wells depth-wise?  I recall measuring and finding more than a quarter of an inch difference.

Thanks,

Doug

DHC6

My Feedback: (6)

FlymoreRC

Hi all,

I'm still interested in what other motors, besides electric & the EVO40cc, are being used.  Love to hear from others.

But in the meantime,  If you doing the full cockpit option, here's a supplier of 12 inch pilots.  I just bought one, and they are excellent detail and quality for the price paid.  The american pilot even has the flopply parachute for him to sit on.

http://www.rcuniverse.com/market/item.cfm?itemId=869479

Let's not let his forum die, too many P47's are being sold and more information is needed on best practices for this new plane.

Michael