Craig-RCU

Hey all you Gee Bee R-2 lovers! I had problems with the stock wire gear twisting on hard landings with my Great Planes Gee Bee R-2 causing the wheels to contact the wheel pants. This caused a braking effect on the wheel resulting in nose overs. So, I bought the Robart struts for this plane. After I installed the Robart struts, I noticed that they compressed fairly easily for a 12lb plane and guessed that they would probably bottom-out on a hard landing and let the pants contact the ground causing nose-overs.

The real Gee Bee R-2 had wheel fairings attached to the wheel fork with telescoping pants to prevent this from happening, so I decided to do the same. I couldn't use the scale, molded-in joint as the telescoping joint because the Robart struts are not parallel to the leading edge of the pants. I had to make the joint further up the pants instead. The Robart struts compress just less than 1", so the joint had to be at least that far from the molded-in joint to avoid contact with the added sleeve. First, I drew the cutout and sleeve overlap areas on the pants. The sleeve would be made out of aluminum roof flashing and be glued to the wide end of the pants and overlap the narrow end 1/4". The area to be cut out is scribbled over in the picture below.

Craig-RCU

BTW, I chose to make the new telescoping joint perpendicular to the leading edge of the pants for simplicity of construction's sake.

Then, I carefully ground down the root of the pants to make them center on the Robart struts properly when they were tightly screwed onto the wing. The wheel fairing was then fastened to the wheel axle with 6-32 screws and nylon spacers carefully fitted and cut to length so as not to put twisting forces on the pants that would cause misalignment when the cutout area was removed from the pants. The plywood inserts that will be the base contact points for the fastening of the Robart struts to the wheel pants (originally glued in place for the stock wire stuts to bounce off) are not parallel to the strut forks, so the nylon spacers need to be slightly angled on one end to make stable footing.

Craig-RCU

A third 6-32 screw and spacer 1" up the fork from the axle was also needed to stabilise the wheel fairing in pitch attitude (I considered adding a fourth screw and spacer on the other side of the fork, but three seem to do the job very nicely).

Craig-RCU

The next step was to fit a 2" wide strip of aluminum flashing around the pant.

Craig-RCU

Time to cut out the 1" shock area.

Craig-RCU

Superglue the aluminum sheathing back in place at the wide end.

Craig-RCU

...And a video of the finished product with white monokote covering the aluminum. I think this strut setup should be robust and be able to stand up to a good pounding. I'll add a flight video ASAP.

http://www.rcuvideos.com/view_video....8f85b1007cd40b

TomCrump

Excellent idea and implementation.

Thanks for posting this.

Craig-RCU

Uncanny, my thoughts exactly! Thanks for expressing yourself so eloquently.

Craig-RCU

Hi all. I finally posted some video of my Gee Bee with Robart struts and the telescoping wheel pants built in this thread. The video shows a couple of hard touch and gos and the struts and pants held up very well with no nose-over tendencies. So far, I'm very happy with the performance of this setup.

http://www.rcuvideos.com/item/L0JVHXLZ3RYS2JFY

TomCrump

Since the spats on the Gee Bee are similar to that on the JU-87 Stuka, I plan to incorporate your ideas on my next Stuka build.

Congrats on your success. [sm=thumbs_up.gif]

Craig-RCU

Thanks again Tom.

Craig-RCU

I had some more thoughts about this project that I thought might save some labor. If I were to do it again, I would make the sheathing out of fiberglass instead of aluminum because the aluminum rubs against the fiberglass lower pant and leaves a dark residue. The residue wipes off easily enough with Windex though. I think fiberglass would have been easier to do also since I could have just waxed the pant in the area that I covered with aluminum, applied fiberglass and epoxy, wrapped it all tightly with wax paper or plastic wrap for a smooth finish, remove the cured fiberglass sheath and then cut out the 1" wide section from the pant. It would have made a perfectly fitted sheath for the pant that doesn't leave a dark residue.

Craig-RCU

Just re-uploaded the video in post #7 http://www.rcuvideos.com/video/GBshocks-wmv

brezel53

Hello Craig,

old thread, but evergreen model....just love the R1/R2s.

Great improvement, that was inspiring me and essential for all "wheel-shoe" -planes.

I did the same with my Hobby King Gee Bee R2, i`ve used the Seagull Gee Bee Z struts and divided the pants at the lower section.

Here´s a video on youtube:

[youtube]http://www.youtube.com/watch?v=GF_iLptvDwQ[/youtube]

If you read this, do you still have a Gee Bee R2?

Best wishes,
Wolfgang

opjose

Where are the original images?

I'm interested in doing the same for my Gee Bee.

brezel53

Hello opjose,which version do you have?I can post pics of my Hobby King Version later, if you are interested.Wolfgang

opjose

I have the HK 1.20 size Gee Bee.

Thanks...

Pictures can also be hosted here and uploaded to your Gallery.

If done, you can click on properties, copy the link and even imbed them into messages.

That's what I usually do to avoid messages appearing without images within posts.

e.g. If I insert this link into the post.... with the {image}{/image} ( substitute brackets instead ) modifiers...

http://images.rcuniverse.com/gallery...umb-231745.jpg

The following image appears...

Craig-RCU

Very nice job! I like the position of the joint on your wheel pants better than what I did, because you don't need any sheathing to cover a 28mm gap as mine did. Have you flown it yet with this setup? I still have my R2, but haven't been flying for a number of years.

brezel53

Hello Craig,

great, you´re here. Thanks for the good words. Yes, i don´t wanted to use additional material. Unfortunately the Gee Bee is unflown....less time.

Haven't been flying for a number of years your gee bee or in general?

Best wishes,
Wolfgang

brezel53

Hello,

here are the pics of my mods:

1. Here you can see the lousy glued hardwood block, one cracked out, when i placed the model carefully on the floor, imagine that!!!
But it was the start to do the modifications:



2. Here´s my added hardwood block to fix my additional brace (Graupner tube 8mm outer/7mm inner diameter, strong, but very light). The hardwood block is fitted without gap to get as much contact to the surrounding wood:



3. The upper joint with the Seagull strut:



4. I used the old cutout film to close the hole again, with tesa, not perfect, but a fast fix:



5. The upper part of the pant, note the cutout for the wheel fork (not mounted in the picture):



6. the other side:



7. the wheel fork with the lower pant. I glued two plywood blocks per pant and fixed them to the fork with 3M Dual Lock, great stuff, almost free adjustments possible and the pants can come loose in accident case. Note:i had to rebent the forks to fit with the HKGee Bee pants, the Seagull pants are wider.



8. Wheel fitted. Because of our grass airfield i decided to let the wheel "look more out of the pants", sorry, i don´t know how to explain that better...



9. Complete assembly. If you look close, you can see the cut outs of the upper pants...i can live with that... Note:I have not glued the wings together and i am sure it is not necessary because of the aluminium link tube.



Thats it. 90% i would say, because i think it would be necessary to stiffen up the struts laterally with wires.

Wolfgang

opjose

Very NICE!

Thanks for teaching us "how it's done"!

Craig-RCU

You're welcome. You'll have to let us know when you maiden. The only thing that I've been flying in the past few years is the Syma S107 indoor coaxial helicopter. 3M Dual Lock is an interesting choice for fastening the wheel fairing to the wheel fork.

FrY10cK

This is a great thread. But can someone clarify for me the difference between the Seagull struts and the Robart struts?

The Robarts are spring loaded but not hydraulically damped while the Seagull struts have no springs at all or am I wrong about this?

I'm still thinking about buying one of those Hobby King Gee Bee R2s.

brezel53

Hello,

the robart struts are high quality, pricy and especially designed for the Great Planes Gee Bee R2.
For the Hobby King version you would have to modify the wing attachments.

The Seagull struts are "cheap", qualitiy is quite ok, much play etc.

But, the Seagull struts are a "drop in" replacement, and thats it!

Here on the photo you can see on the left the Seagull strut and on the right the HK wire sh%& :



BOTHversions (Seagull /Robart) are spring loaded and no hydraulic damping, what would be the most effective improvement!
I thought also to add a rc-car damper.

Wolfgang