Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Guys,
Anybody flying this plane and had to put lots of down trim in it ??
Before i flew mine, i noticed that the engine firewall has 2+ degrees of up thrust. I notified great planes and they said it is "designed in the airplane"......BULL!!! When i flew the plane ,it required 24 clicks of down trim to get it to fly level. (I checked stab and wings prior, with incidence meters, they are right at zero, balance is right on the money too). when i landed the plane, you can see the elevator drooped down. Well, another guy shows up at the field with exact same plane, and when he turned on the radio, you guessed it! The elevator drooped just like mine. I looked at his prop from the side, sure enough, it has upthrust like mine. I asked him if he is going to fix it, he said, naw, it flies okay. I guess, he is satisfied with mediocre performance!. I have a friend in Texas, and he said his Giles 202 is okay, but his friend has one and it is like mine, he had to add a lot of down trim.
Well, i put some shims behind mount and got the engine to 1/2 degree down thrust. I flew the plane and it still needed 10 clicks of digital down trim, but it handled much better! I now put two degrees of down thrust in engine, and will fly it monday. I will report my results monday night on here.
I would like to hear from anyone who has had to put in a lot of down trim in their Giles 202......Thanks Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

My friend is flying his tomorrow'i'lltake alook and see if his is like that.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Wildthing,
Do you know if this is his maiden flight on the plane?
If it is ,and it has up thrust like mine did, tell him to be aware that when the plane leaves the ground it might pitch up nose high, and stall. Mine did just that, and i had to shove the stick down hard to get it level.I was Lucky, that the enginge was pulling really nice and strong, being a gasser, it had the power range up, if it would have been a methanol two stroke, i don't think i would have been able to save it, as it would not have been at full power level. Thanks for replying, Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

He has a gollon thrue it at least but i remember when he first flew it the elevater trim was way off,never checked the upthrust but will warn him today.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Wildthing,
thanks for the reply, this does not seem to be an isolated problem ,with just my giles, as now i know of four planes that have had this problem.......And, i wonder if any one has crashed on take-off , because of this problem, that was not aware of the upthrust! it will be interesting if i get more replies on this. Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Well, i flew the bird again today, and still had to put 10 clicks of down trim in elevator, to get it to fly level. Came home and put in 3-1/2 degrees of down thrust in engine! went back to the field, and flew the bird once more. NO CHANGE! still needed 10 clicks of down to fly level.
I came to the conclusion that MORE down thrust is not the answer to the problem. I turned both ailerons down a half turn,and it helped quite a bit! I figured there must be something way off, or out of line. But the plane is now flying very well .
When i got home, i put four incidence meters on the plane(one on each wing tip, one on each elevator half) every surface was at ZERO! This is a mystery to me.If any one has any answers to this one, i sure would appreciate their input. (it's not a balance issue, as i double checked it ,and it is right on the money)
I put the engine back to 1-1/2 degrees down thrust. Set the elevators at 1/2 degree down ,and ailerons1/2 degree down.
I will fly it wednesday to see how this setup is working.
Thanks for reading this , Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Hey Paul,
Sorry to hear about all the problems. How is it if you roll inverted? Need any down stick? How about if you roll 90 degrees and do a pylon style turn, Nose pitch up? I'm wondering about the CG placement. All planes will need to be properly trimmed and the manual specs aren't always the best....
Rick

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Rick,
Thats whats puzzling,when i roll inverted, the plane is almost perfect, i do have to hold a fraction of down elevator. But if i remember , i had to do that in all my birds when i go inverted.
Roll rate is perfect too, even slow rolls are outstanding.
When i hang it knife edge, its also perfect, half throtle she just hangs all the way across the flite line, if i go full throtle, she will knife edge loop. I also chop throtle from full, and she doesn't fall or climb, when i go back to full throtle. I have not checked it for 90 turn then pull pylon turn, i will try that tomorrow.
Thanks a lot for your input.........Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Sounds to me like there is an incidence problem.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Outcast,
Thats what i suspect, i have checked everything and it is at ZERO. Since it is an ARF, there are no plans, and Great Planes has nothing on their site to say what it is supposed to be.
Thanks , Paul

Engine Thrust
 

I would check to see what the plane does when you go from full throttle to idle in flight. If the plane rises immediately after you remove throttle then you have too much down thrust. If the plane dives after you remove throttle then you have too much up thrust. This only applies after the plane has been trimmed for level flight.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Snothead
Thanks for your reply, i have done that several times. There is NO change, plane does not climb, or dive, when i chop power, then add full power. Thats why it is so hard to figure out what is wrong, and why i have to have down trim in it . It definitely was not right what great planes said, that plane requires 2degrees upthrust. I almost lost it when it left the ground , had to put lots of down trim in it

1 degree of upthrust
 

This may be a stupid question, but... did you build the wing upside down? i.e. Anhedral instead of diheadral?

I've been flying mine for a while. With the CG set at the rear of the specs and 1 degree of upthrust, it is totally neutral inverted or upright. But it is a real handful to land. Incidence is 0 degrees, right thrust is ~3-4 degrees (had to offset the engine to line up with the cowl). Weight is a touch under 12 lbs.

I moved the CG to the forward position. It is now a joy to fly. Takes a lot of expo to tame the elevator. Needs full rudder but with that it can do a knife edge loop. Tumbles like a leaf. Elevators, walls, et-al. no problem. Suprising stable for it's ability to tumble. I'm kind of diggin' it!

OS 160, Perry pump, 16x8
5ea 5925's
1ea 225
Jr1400
Futaba radio gear
YMMV.

Best of luck with yours,

Scott H.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Scott,
No, its an ARF so wing has angles already built in. Color is different on bottom of wing too.
The firewall has right thrust of about 3-4 degrees, which i'm not sure that it needs all that to begin with, as i had to put in a little left rudder trim , because it was turning right, just slightly.
CGis good, because it handles good,and lands like a ***** cat!
Thanks for your input, it is truly appreciated !

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Hey Scott,
How does yours run with the perry pump? I just bought one and a 24oz tank and I am undecided as to wether or not I should mount the tank at the CG or just leave it in the stock location. Also are you using a Pitts style muffler or the stock one? I have no Idea what all these changes are going to do to the fuel pressure....
RP

Paul,
If there is no change with chopping the power, then I don't think the thrust line is an issue. I know the 3D hotdoggers like a degree or two of upthrust actually for hanging on the prop. Not sure what the problem is with your plane. Maybe the wing incidence shouldn't be zero. If you do the long vertical dive does it belly in or out to the canopy, or is it straight down?
RP

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Rick,
I have not tried that test, but i will today.
What will that tell me?
lets say for example it pulls towards canopy, will that be a wing angle incidence problem?
Sorry i can't help on your tank question, as i have a MV VS gasser in my bird. Thanks for your input .......Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Hi Paul,
it's a way to check if the wing incidence is proper for a given model. Someone here gave me the link to the page with a nifty trim chart but I lost the link. It basically says that if the model pulls (in a straight dive - power off) to the canopy you should increase wing or stabe incidence. Pulls toward the belly then reduce wing or stab incidence.
I haven't tried this yet, but the rest of it seems logical enough.
Rick

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Rick,
Thanks for the info, i am anxious to see what it is going to do, in that test maneuver. Only problem will be if it pulls in either direction, how do you fix it since stab is now permanent, and wing saddle is not too easy to change because of its thick mass?
Guess i would have to set incidence in stab or ailerons slightly ,and be happy with that. like i said a little earlier,i have the stab and ailerons set a 1/2degree down , and i am going to see if that makes any difference today. Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Put a shim between the wing and fuse at the rear of the wing(start with 1/16 then 1/8)and see if this helpsThe link i think rick might be talking about is www.geistware.com(rc proving grounds)

Perry Pump
 

Paul,
I got mine from a guy who built the wing upsidedown. That was why I asked. It can be done. Wasn't trying to be a smart-alec or anything. Hope you didn't take it that way.
But I think Rick maybe right. The wing saddle area was pretty rough on mine. Like someone had to grind out the area to get the wing incidence correct. There is also a good setup sheet in the Futaba 8U manual. It is probably the same one Rick is refering to.

Basically if it pulls to the canopy on a verticle downline you need to sand the trailing edge of the wing saddles. If it pulls to the wheels, add a shim, but make it cover the full length of the root so that you don't stress the saddle in one spot.

Rick,
The OS runs very well with the pump. I used large line with medium line for clamps. the perry pump comes with small nipples. So the medium fuel tube clamps tightened up the seal. I also used the large style craptrap. The carb settings are very close to what you would have with a stock muffler pressure setting. Use some thin double side tape, or a dab of shoe-goo, on the pump if you use the stock clamp, or it will vibrate out.

I didn't make any adjustments on the pump. Of course there is no muffler pressure needed with a pump, so the fuel stays clean.

Unless you cut out the floor of the cockpit, the tank won't quite go back to CG, but far enough. I'm running a 20 oz. tank and am getting 12 minutes plus a bunch, flight time. Very rarely does it fly above 1/2 stick. Mucho Grande power! I used a Slimline Pitts muffler. If I could do it over I'd use the Bisson Pitts style w/70 degree pipes. That way the cowl could go on with no extra holes.
Since the 160 broke in I haven't touched the mixture screws. I could bolt the cowl on and forget it!

Happy Flying!

Scott H.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Scott no offense taken, i did not think you were saying it to be a smart alleck.. Well i flew it yesterday with the 1/2 degree down ,in ailerons and stab, and it has definitely got to be an incidence problem, as i now had to add 6 clicks of UP digital trim,which is not all too bad, as the bird seems to be flying much better as i am getting it "dialed in". i did take it up high and dive it straight down,(no power) she is slightly pulling towards the wheels. (did it three consecutive times with same results.)
I took the 1-1/2 degrees down thrust out of engine, and i now have it at 1/2 degree UP thrust. i am going to see if that makes any difference, and will also shim the rear of the wing, (which might accomplish the same thing as lowering the ailerons)
Thanks again for your comments, and you too wildthing....
Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Just a small comment on my avatar, that is my pro dartar sloping with his seagull "buddy" in Morro bay California.
I was finally able to post my avatar, thanks to Marc, our moderator, and planeinsane.
Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Paul,

How did your Giles turn out? I maidened mine last weekend and needed 10 digital clicks of down trim... I have added a 3/32 shim for down thrust and will check next weekend...

Chris

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Chris,
Thanks for your post. I now have the Giles flying great!
Some one suggested that i put a 1/8"shim under the BACK of the wing.
THAT is WRONG! Don't do that, you need to drop the front of the wing down about a 1/2 degree, (since my stab was expoxied in already, and i could not change the incidence, without major surgery,breaking the stab loose, that is why i chose dropping the front of the wing) .I did this, and the plane flies great with out adding any trim! (I elongated the dowel holes down about 3/32", then made a new plywood plate, with new dowel holes, and epoxied it behind the existing bulkhead, then filled in the gap on the fuselage, where the wing sets, with epoxy and micro baloons) .
Strange, i was just at another flying site about a half hour ago, and a guy has the same plane sitting there, and you guessed it, the elevator is drooping just sitting there!! He said he has to fly it with all that down trim! That is the FIFTH Giles i have seen with my own eyes, with the exact same problem!
So GREAT PLANEs, Tell me you don't have a problem with incidence!! Speaking of Great Planes, i wrote them a long email, about the wrong upthrust, and wrong incidence, but Kraig, their tech guy never emailed me back!
I don't know why they don't put and addendum in each kit telling modelers, what they need to do, to make it fly right!
That would certainly be better than not saying anything about their problem. What if some poor unsuspecting modeler, that is un aware of the problems, goes out and has an accident with the plane,and possibly hurts someone! Is that the way to address the problem, by NOT ADDRESSING it at all, maybe hoping it will go away by it self????
They flat lied to me when i asked them about the up thrust of more than 2 degrees, they said the plane is designed with it !! I believed them, and on the first flight almost stuck it in the ground , because the plane shot straight up, and almost stalled! Hope this is of some help to you,good flying,and happy landings, Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Paul,

Thanks for the information...

When I built the plane I made the wing and tail incidence 0-0.. Are you saying this is not correct?

Chris

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Chris,
When i checked my bird, before i flew it, if i remember correctly, the wing and the stab were at 0-0. Evidently there is some other issue with this plane. I believe it could be because of the short tail moment. Maybe Great Planes designed it at 0-0, but it sure does not fly that way. Could be that is why pattern planes have such a long tail moment. All planes are different, some need to be at "0", others need incidence, some negative, some positive. I guess you could say "its the nature of the beast". All i can tell you is with my front of the wing down, that half degree, it flies perfect.
I guess you could add nose weight, that would help it fly with less elevator trim, but i prefer to have the CG where it belongs.
Hope this is of some help to you ....... Good luck, Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Hey Paul,
I think I'm going to confirm your findings. How did the plane fly at 0-0 on the knife edge? Did it pull tothe belly?
Rick

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Rick,
I can not give you an answer to that, as the plane now has the 1/2 degree down incidence in the wing. i don't recall any pulling to the belly in knife edge, but i was not looking for that either. I am going to fly it today, i will see what it does on knife edge.
Let you know later. Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Paul,
Have fun, wish I could go - you know how this work thing gets in the way.... How did you get the -1/2? sand the wing saddle? More important is that you got rid of all the uptrim in the process, is this correct?
Rick

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Rick,
just got back from the field, bird is flying great. I did put it on knife edge, and it does pull to the belly. Not bad though, i can live with it!
It does fly great inverted though. I drilled out the front dowel holes down, about 3/32" then made a new plywood plate ,and epoxied it in behind old bulkhead, to accept dowels, then filled in gap in fuse with epoxy& micro baloon mix. I guess you could sand the rear of the saddle too, six of one half dozen of the other, LOL
Yes, the stab is now flying at level with no down trim!!
Good luck, Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Gentlemen,

The thrust angle is VERY VERY VERY extensively tested and is 100% accurate. Thrust angle is not set to give you a nice looking stab/elevator mate, it is set to keep the model from changing pitch trim when power is applied. As someone stated along the way, if hte model does not pitch down hard, suddenly, upon pulling back the throttle, then the model does NOT need more downthrust.

It sounds to me like a wing incidence/seating problem, and I am passing this thread along to our R&D manager immediately for his research and to check the wing/stab measurements on the flying prototypes and post-prototype models. Nearly every member of our R&D staff have one of these, and love them, so we should have plenty of data to work from!

Paul, I'm sure it was an innocent mistake if your email was not responded to. We answer literally thousands of pieces, and mistakes, system failures, etc, can and do happen. Please do note that your indication that we are "dead wrong" about the thrust angle is inaccurate.

Sincerely,
Mrs. AnnMarie Cross
Senior Manager, Proprietary Services and Support
Great Planes Model Distributors
[email protected]
www.greatplanes.com
www.bestrc.com
NO AUTORESPONDER

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Thank you AnnMarie for taking the time to answer this concern here at RCU.
Although I haven't heard your problem before in my neck of the woods guys, I appluad your efforts to find the fix.
Now that AMC is on it, I'm sure you'll get the answers you need from GP.

Good luck,

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Wow Ann,
Thanks for the Info. I have duplicated Paul's problem. New and out of the box 0-0 the plane needs a significant amount of down trim for straight and level. This really caused my plane to pull to the belly in knife edge.
I need to get that down trim out of the plane (I like the CG as it is pretty nutral now) to tame the pulling to the belly on knife edge. I'm going to try -1/2 incidence like paul, but I'll wait to hear what you say.
Thanks
Rick

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Annmarie,
Thank you for taking the time out of your busy schedule to comment on our posts. I would certainly like to have some hard facts, as to why this plane is designed this way. Please do not get me wrong, as i am not bad rapping GP, i think you folks have done a fantastic job on this airplane, as i have commented in my earlier posts, there is "no way" I could have built and covered this airplane for the price I paid for it.
I think my biggest gripe was before i flew the plane, i noticed the huge amount of "upthrust" in the firewall, so I did notify you folks, and was told that it was designed with that much upthrust.
So when i made the first flight, unexpectedly, the plane pitched up nose high on take off, and i nearly lost it! I had to put 28 clicks of digital trim in it to get it to fly level. So i started experimenting with the thrust angle, I even had the engine at 3-1/2 Degrees of down thrust. this did not cure the problem, as i still had to put down elevator trim in the plane. So this told me that i also had an incidence problem, which i corrected by dropping the front edge of the wing.1/2 degree. I put the engine thrust angle at 1-1/2 deg. down thrust. The plane now flies very respectable.( Weight and balance were checked numerous times, and are to specs.) I believe the plane has two problems, thrust and incidence, as i had to change both on my plane.
When checking all the posts on the web, i find out that it is not an isolated problem with just my plane! Like i said, earlier, i know of 5 of these planes that i have seen personally ,with my own eyes, that have the same problem.
Like you just stated yourself, you believe it is a wing/incidence problem too. It is good to know that you are making your R/D guys aware of this problem, I hope you post a reply as to what they find out, is causing the plane to require lots of down elevator trim.
Ann, I do apologize for making the statement that you guys were " dead wrong", that is not accurate, as you stated. but i guess by making that statement, i got Great Planes attention. As for my emails, not being answered, you could be right about it being an innocent mistake.
Again, thanks for taking the time to answer our posts, and also my thanks to RC Universe, for such and outstanding job they have accomplished with this website!
sincerely, Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Paul,
Being married to the test pilot, trust me when I tell you that the stock thrust angle of the models that were sent as "ok'd for production" was dead on. That is mike's biggest pet peeve and he works VERY hard at it.

I firmly believe what you have is solely an incidence problem, assuming your model has the called for 1 degree of up and 2 degrees of right thrust, as that configuration was PERFECT for the test flying.

I suspect there is something wrong with wing saddles or with stab saddles, and have folks looking into that now.

Please note that CG positioning is CRITICAL to how much elevator trim you will need and even more so on how much the model pitches to the belly in knife-edge.

Sincerely,
Mrs. AnnMarie Cross
Senior Manager, Proprietary Services and Support
Great Planes Model Distributors
[email protected]
www.greatplanes.com
www.bestrc.com
NO AUTORESPONDER

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

AnnMarie,
Again, thank you for your reply. It is great to know that, a large manufacturer, such as GP takes a very real concern about their products. Some companies would not even have the decency to reply.
I guess you could say that my mission is accomplished, as you are now aware that there definitely is some sort of a incidence problem, because of the different posts you are reading, that all say they have to put in down trim in the elevator.
My bird did not have one degree upthrust, it had better than
2-1/2 degrees of up thrust. I am not so sure as to the fact that it is good that i have 1-1/2 deg. down, i am going to put the thrust at the required 1 deg. UP as you suggest. I am also going to check my right thrust, as it looks to be more than the required 2 deg.
After that, i will see if there is any change in level flight, when power is chopped, or added.
I will inform you Via email.
Keep up the good work Ann. I have heard rumors that you new Patty Wagstaff Extra 300 is an AWESOME airplane!!
sincerely, Paul

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Hello AnnMarie and Paul,
I would also like to second Pauls comments about the quality and being able to build this model for the same money. I am very happy with it. When I set mine up I Put in 1/2 degree of upthrust before I drilled the mounting holes for the engine. (I was actually aiming for 1, but when all was said and done, it was 1/2). With )on the wing and 0 on the stab, I needed considerable down trim, maybe over 1/2 the trim on my standard transmitter and it was definitely visable upon inspection of the stabilizer after flight. I plan on putting some negative in the wing incidence and will let you know how it works.
PS I think your customer service department is top notch and doing a fantastic job. I'll be a GP customer for life.
Rick

continued Discussion
 

Hello friends,

I want to get in this discussion too. I know I might be late but need to confirm many of the same issues as the other fellas. I got this plane this winter and fell in love with its style, looks and great price. There is NO WAY anyone can build this plane for the price of the ARF. Keep up the great deals GP!!!

However, I concure with the guys about the flight characteristics. I had it set-up by the book. The CG was right on, the mount flat on the firewall, wing and stabs at 0 degrees. I was using the suggested ST 2300 and Trueturn 4" spinner. What a beauty (took third place at the mall show)

On the first flight the plane took off in about 15 feet pulling up in to a loop. I added a ton on down to get flying level. At first I though I was tail heavy. When I cut the power it dove to the ground. I was fortunate to still have it. I began to do research on the net when I began to read of the possible thrust problems. Now on the sixth flight I am getting closer. The engine is 1 degree down, tail still has down in it, and I added three turns of the aileron linkages in to give it a more positive incidence. I now flies straight in power and cut power, tracks straight in a 90 degree dive, but still pulls to the belly on knife edge. I have some flight time on video that I am going to make digital for you geeks out there.

Personally I would love to get my hands on one of those the GP guys are flying. I want to compare, cause something isn't right. Don't worry though cause I still love the plane still a little shakey when flying it, cause I am not sure what it is going to do. So if you are ever in South Central Indiana stop by our field it is very nice. Paved runways picnic area, great people, and great place to fly.

Gp Giles 202 1/4 Scale, Upthrust Problem!!!!
 

Ricmussman,
Thanks for your reply, this is just another one for the record books. I guess, i opened up a can of worms for GP on this one.
But I am sure that they would want to know if they have a problem with one of their products. I too wonder how this one got by their R&D guys, as ALL the Giles i have seen have the same problem. I am glad that AnnMarie had the decency to reply to our posts. She was willing to go way out on a limb, by saying that there is an incidence problem.That just shows That GP IS a great Company in my books! It will be interesting to hear what conclusion their R&D guys come up with....Paul

Rickp g-202 &Levittown
 

Hi! fellow flyers! I got to reading all of your suggestions when I saw the GP Giles 202 post, I have had that same problem about almost stalling on takeoff, I get up good speed and all of a sudden mine wants to go straight up, I will try some of your tips, In the meantime Rickp I grew up in the southern part of Hicksville near Levittown... Wishing Lane off of Jerusalem Ave. near Scooter Lane, I have moved in 1978 and was not into Rc until about a year ago, where do you fly at in that area? I haven't been there in about ten years and everything was so changed then.