GP Gee Bee R2 ARF
 

Has anyone flown the new Great Planes GEE BEE R2 ARF ?

Thoughts ? Recommendations ?

RE: GP Gee Bee R2 ARF
 

Well, it looks like I will be one of the first to do so.

I,m hopeing to do the deed today or tomorrow (10/3 or 10/4)

I have 42 flights on my Kyosho GB-Z and IF the GP R2 flies half as well as it does, it will be pleased.

Will advise.[8D]

Kerry S.

RE: GP Gee Bee R2 ARF
 

If you look though this forum for a posting titled "GP GEE BEE" you will find some info with flight reports. I am working on mine, so I have a while before mine is flight ready. Let us know how the flight goes.

RE: GP Gee Bee R2 ARF
 

I put one of these together for another club member and flew it on 9/21. A Saito 180 was installed and was more than enough power for the Gee Bee! I had to add 2 1/2 oz of weight to the tail to get it balanced correctly.

The take-off was straight down the runway, it was flown at 1/2 throttle, the first landing bounced, ( I was concentrating on the throttle and touched down at too fast of a speed) and the second landing was smooth.

Great Planes has a winner here!

RE: GP Gee Bee R2 ARF
 

Are there any other threads with the GP Gee Bee running? I can't find any ... looking for the best ... thanks !

RE: GP Gee Bee R2 ARF
 

The following is a report on my first 2 flights of my GP GB R2 ARF yesterday 10/03.

It was flown from a grass field of 480' length, temp was 58 dgr. and wind blowing at approx. 15 mph, 30-45 degr. quartering crosswind.

The GB was fitted with the factory recommended throws.

TAXI: The GB taxi's very well on turf with only a slight lightness on the tailwheel as some minor bounce is noticed.

TAKEOFF: is striaght as an arrow, dispite the quartering crosswind and when it lifted of in approx. 10 feet after application of full power, is was absoulte wings level with almost no aileron input considering the power I have fitted into my GB, more on this below.

FLIGHT: The GB WILL let you now if you have not gotten the Rudder on neutral as it will dog track (side slip) until you trim the rudder correctly. Once done the GB tracks like an arrow with very solid flight at 50-60% power. Loops are as big as you want and the rolls are quick and the knife edge is beautifull.

After landing, the trim settings where as follows: Ail.- 3/32" Right, Elevator - Dead Neutral, Rudder, Dead Netural. (kit has down thrust and right thrust built into the firewall and appears to be just right.) After test flight throws: Ail, reduced by 10%, Elev. reduced by 20%, Rud, as is per manual.

LANDING: This was a bit interesting dispite having 42 flights on my other GB, a
Kyosho "Z". On my first approach, I noticed that you truely do need to maintain some power as per the manual due to frontal area. Once over the threshold, I redcued power to just above idle, decended over the corn and began the flair and observed a VERY sensative elevator which produced a small "Gallop" when attempting to flair, landed without incident.

2nd landing was much the same and I came to the conclusion that the Eleveator has to be set up on dual rate to eliviate this sensativity at LOW speeds. While in powered flight, the elevator reaction is PERFECT for the flight regime in all power settings. WARNING, if using dual-rate to eleviate the gallop on flair to landing, upon touch down in the grass, you may find that you will NOT have enough elevator throw to keep the nose from tucking under !

My R2 came in at 12.7# (factroty spec's are 11.25 -12.25#) and I only added 1.4 oz. of lead to bal. and I placed this inside of the pilots head. Considering the mod's I made to this model, these where EXCELLENT results.

Because I have flown in the USRA racinging events and wanted similar performance, I made the follwing changes to the my GP GB-R2:

1. All pushrods where changed up to 5/16" spruce dowels and ALL PR wire rods and clevises are 4-40. It is important to MINIMIZE the length of the PR wires to eleviate ANY flex. I disagree GREATLY with the manual in this area of construction.
2. The pushrod mid-span support was changed to 1/4" Spruce.
3. Repalced the "laminated light ply" wing spar with a single pc. 5 ply Birch ply spar.
3. The main wheels where up-graded to Sullivan Light Weight 4-1/2"
4. Installed a OS. 1.60 FX 2 cycle w/ stock muffler w/ Zinger 18 x 6-10 wood prop. on 10% fuel,w/stock kit supplied 14+ oz fuel tank.
This required the following mods:
a. Spilt the kit motor mount to allow for the bolt-up to the OS 1.6
b. Modify the "muffler tunnel" in the bott. of the fuse to allow for the passage of
the stock OS muffler.
c. Generated a "Drill pattern" on AUTO-CAD to properly relocate the OS 1.6 to insure the muffler would fit down thru the "tunnel"
d. Add an 1/16"x 1/4" ply strip around the entire OUTSIDE of the cowl mounting ring. This is needed as the cowl will be slightly FORWARD of the 2" position recommended in the manual. This is to allow for clearnace with the front of OS1.6 muffler.

The results of these mods., while not for everyone, has added only .4# to the stock model, HOWEVER, the performance is outstanding and this GB takes it in stride ![sm=lol.gif]

A note of observation between the Kyosho GB-Z and the GP,GB-R2 is the MAJOR difference in the Wing Incidence with the thrust lines and stab incidences being nearly identical. As a model designer of over 25 years, I feel that the Wing incidence is contributing to the "balloning" tendency the GB-R2 has when attempting the falir to landing and to satisfy my curiosity, I proceeded to measure wing incidences and found the K-GB-Z at +1.5 dgr. to the GP, GB-R2 at +4 dgr. !!

The reason to proceed to compare models is that while the 2 models are IDENITCAL in being ROCK SOILD in take off and flight, the landing behaviors are totally different with the GB-Z being dead smooth on landing flair without the use of dual rates vs. the R-2 and I wanted to understand why.

HAVING SAID all this about the wing incidences, this is NOT a bad thing but ONLY a designers observation and I will continue to fly the R-2 "as is" to determine the best power setting for approach and landing.

Until then, can't wait to get back to the feild as my R-2's vertical is truely "ULIMITED".

I will be glad to provide the OS-1.6 drill pattern data and muffler tunnel mods to anyone wanting to install this engine into the GP-GB-R2.

All comments and replys from others that have flown this model are welcome.[8D]

Best Regards:

RE: GP Gee Bee R2 ARF
 

Hi Kerry,

you mention using dual rate for sensitive elevator?

why wouldnt you use exponential?

RE: GP Gee Bee R2 ARF
 

I was also wondering why the wing and stab were almost 5 degrees different from one another. The wing is positive. Didn't measure thrust line, but there's a lot of down and right built into the firewall. With the fiberglass fuselage, I'd expect the angles to be pretty close to what the designers wanted in the first place.

My Gee Bee has a Saito 150 (I had one on the shelf). It weighs 12 lbs 5 oz, with only added item being a DGS-2 on-board glow lighter. No added weight needed to balance.

Test flights later this week.

RE: GP Gee Bee R2 ARF
 

I have tried expo and I hesitate to use it large percentages as it diminishes the available trim movement as well as this plane reacts quite differently in pitch when on high power verses low power settings.

However, I went back to the field on Sunday and programed in an additional 15% expo on the Elevator (now at 35%) and increased my throws back to the "origianl" 5/8" U & D.

The landings where significantly better in pitch control.

I then proceeded to program 50% expo on the elevator and went back to 1/2" U & D max throw and I now have a very smooth transition from flair to wheel landings on grass with plenty of available elevator to prevent nose over tendencies.

With this setting, I'm very please now with the ENTIRE flight envolope.

All other throws are per the manual. (Rud -1" Ail.-7/8")

Best of luck to all. You will lbe very pleased with this very unique airplane.[sm=thumbup.gif]

RE: GP Gee Bee R2 ARF
 

What engine runs best on this ship?

RE: GP Gee Bee R2 ARF
 

Vampire this question is directed directly to you! You sound very experienced and know what you are talking about, I would like to know if this is a bad idea or not. Everyone else is very welcome to answer also, thanks!

Soon going to be working on building Great Planes Gee Bee ARF. Wondering what methods I could use to conceal servos and linkages to give the plane a more scale like appearence. So far I have thought of getting a thick piece of wire for each aileron, making a 90 degree bend at each end, finding some plastic hinges which one side can be inserted into the wing, and the other side having a hole to slide the wire through. Then I will make a slot in the leading edge of the aileron so the wire fits flush with it, then drill a hole in the outboard leading edge of the aileron to allow the 90 degree bend to fit inside. Then I will have to drill a hole through the trailing edge of the wing, to feed the wire through. I will then have another 90 degree bend inside the plane to which I will connect a linkage and servo to. Now I could use one servo for both ailerons, as long as I have enough torque. I plan on getting metal gear ball bearing 124 oz/in torque futaba servos for flight controls, the manual calls for a minimum of 40 oz/in. I figure divide 124 by 2 (2 ailerons) and you get 62 oz/in of torque for each aileron, more than the minimum. This setup would eliminate the need for the servos to be installed in the wing and be visible. I could also do a similar setup with the elevator and rudder, but I'm not sure how I would feed the linkage into the fuselage. Please let me know what you guys think about my idea, and if you have any better ideas of yourself. Thank You very much Nick Mathews

RE: GP Gee Bee R2 ARF
 

Hi Nick:

I have scanned the "walking beam actuator" setup as previously discussed. It may be of poor quality so I will pm you the TIF file as well.

Brg.

Kerry S.

RE: GP Gee Bee R2 ARF
 

I am putting an OS 1.60 twin four stroke in mine. They sound so dman good and they are an easy install. They are not as powerful as some other engines, but oh well. I have flown one with this set up and liked it!

RE: GP Gee Bee R2 ARF
 

I was wondering why there would be down thrust on a low wing plane. I can see an advantage on a high wing plane....

RE: GP Gee Bee R2 ARF
 

On any airplane, the thrust line is set to help eliminate changes in trim when powier is changed. The "designed" thrustline is usually determined in flight testing before the model's design is hardened and it's committed to production. Downthrust prevents tendencies to strongly nose up when power is applied.

RE: GP Gee Bee R2 ARF
 

On a high wing plane with a low thrust line, down thrust will help to keep the nose from pitching up with the application of thrust.

On a low wing plane with a high thrust line the application of thrust tends to pitch the nose down. Down thrust will intensify this downward pitching.

I would be very careful about rapidly opening the throttle when close to the ground at low airspeeds. Not the most forgiving setup if you have to "go around" and try another landing.

Perhaps the excessive incidence is required to counter the down thrust.

Adrian