AllModesR/C

Thanks for the link Tom.

52larry52

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AllModesR/C, That's a pretty good looking trainer you got there. My previous guess of it being a Goldberg Eagle is totally wrong. I took a shot at it only seeing the engine bay, and missed with that shot! After seeing the whole plane I think it is an early version of a Hobbistar 60. Tower still sells a much updated version. Does yours have about a 71" wingspan with a semi-symmetrical wing (not flat bottomed) that is held on with rubber bands??? What engine do you have in there?

AllModesR/C

It has a 59.5 inch wing span and the bottom of the wings are flat. I installed a Thunder Tiger GP42 engine in it because I had it from the original trainer that I wrecked. Which was the plane this thread was originally started for.

Gray Beard

My Feedback: (-1)

Every modeler you meet including any long time ARF person will have a box of servos and servo parts. They will even have servo control arm screws sitting in there flight box, it's a given. Most of us even have a servo or two in the flight box just in case. Just ask any club member and they will dig one out and hand it to you.
If you want to stock up on servo screws or parts but don't want to ever go back into your LHS then pick up the phone and just call Hitec, Tower, or Horizon and order a pack for your servo brand.
When most of us started we bought 4 packs of standard servos from Tower or our LHS. I just looked in tower's catalog and a standard servo is still only 8 bucks. Horizon has some pretty good deals on 4 packs and you can get standards or digital in a bundle.
Time for you to start your own collection of little items. In my old box I have a plastic box full of everything from screws to new replacement rubber and grommets.
For the four screws needed to mount a servo I buy the screws from Micro Fastener in bags of 100 for about 6 bucks. These have a hex head with a built on washer and are guaranteed to make your life easier then the screws that come with the servos.

52larry52

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OK, so it's a "40 size" trainer. Looks like I'am totally wrong again! I still say "it's a good looking trainer" whatever it is. Somehow I missed the fact that the original T.T. 40 trainer was lost in a crash. That however has nothing to do with my wrong guesses. I am now thinking (and guessing) that maybe Hobbico also made a 40 size trainer back in the 90's but that predates my RC flying. I was still racing cars back then. OK, I give up....someone else take a shot at it.

AllModesR/C

I'm afraid I am becoming an RC airplane hoarder LOL. I already have three planes and really have my eye on a fourth but will pass because I don't have the space to store them all.

Thank You, I only paid $20 for it off of Craigslist. But it had no motor or radio. It was just too good a deal to pass up since I wanted to transplant the engine and radio from the TT 40 trainer. ;-) I would guess it's from the late 80/early 90's. It sat in the guy's garage for many years because it had cob webs and dust bunnies all over it. Since I don't have a lot of money in I won't be afraid to fly it.

Gray Beard

My Feedback: (-1)

Then look into buying bundle packs of servos. At this time your like most of us and only need standard servos. Something I did and just fell into a deal is I went onto servo City's web site and they were having a close out sale. That happens when a company is bringing out a new servo and dropping the old one. That was just dumb luck but they always have some good deals going. So does Hanger 9/ Horizon. Your going to need them so you may as well start shopping around and hope to fall into a deal like I did. While your on the sites you can locate the screws and little extra things that you often need.

repirazz

https://www.youtube.com/watch?v=m1athb21XjY Found this on youtube. Looks like older hobbico avistar 40. Good call Larry.

[email protected]

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why not go to the flying field and see if someone has a good radio for sle and a good os engine>>>

AllModesR/C

Because I had an engine and radio system laying around

52larry52

My Feedback: (1)

repirazz, You win the "name the plane" game! I was in the right general ball park (hobbico), but you nailed it exactly, you hit it out of the park. I learned a little about the Hobbico "family tree". That early Avistar 40 that the OP has and the one in your video are in fact just a smaller version of the early Hobbistar 60, big brother and little brother. Different sizes of the same airplane. The Avistar that I know is an evolution of this one with a swept back vert. stab, a little different fuselage top shape, and a totally different trim coloring on the covering (red, orange and yellow stripes). I never put them together as "brothers" before. Interesting,at least to me. Thanks for playing, and you may pick up your winning prize from the OP.

Tom Nied

And I'm excited because I picked up a used TT GP 42 on ebay. Because I just happen to like that engine. Thanks Allmodes.

AllModesR/C

I flew the beater twice yesterday. It seems to fly awfully fast for a trainer LOL. Faster than the Thunder Tiger trainer I first flew. I ended breaking my 10x6 prop on landing and was wondering what would happen if I installed a 9x6 or 10x7 which I have laying around? What kind of adverse or positive reaction would I get?

Tom Nied

You have to think of different props like going from a standard 10-6 to a 9-6 as down shifting the engine. It'll rev faster and will accelerate faster. The 10-7 will be trying to move more air and not rev as fast (not accelerate as fast). What's the exact engine again? If it's a 40 size engine on a trainer, I wouldn't go below a 10-6. You might want to check your CG, if its forward that could the reason you're landing fast. Bringing it back just a little will help in slowing it down when landing.

AllModesR/C

Hi Tom, I hope your weekend is going great. I'm running the TT GP42 that runs superbly.The plane is actually a bit tail heavy unless I have my CG points off. I did look at the Hobbico Avistar manual online and it said the CG points are 3 1/4 inches from the leading edge. However, this was for the newer updated version of the plane. I will do some measurements and input the data into the CG calculator app I used for the TT trainer which I balanced perfectly.

Regarding the props I looked at the sticky on top of this section and it said a 9x6 is not suitable for a 40 size engine. A 10x7 along with a 10x6 is fine. Think I'll go with the 10x7 and see how the plane responds.

Tom Nied

That sounds fine. I recently picked up a Thunder Tiger GP 42 on Ebay, and I'm pleased how it runs. I put on a APC 10-6 prop and I'm getting about 3500 on the low side and 11,600 on the high. I think it's a good match.



http://youtu.be/SxQjdigpxiA

AllModesR/C

Yours appears to have a different carb than mine.

jester_s1

A 10x7 is a bit much. 10x6 should be perfect. If you find you want better acceleration, an 11x5 Scimitar will do nicely.

Not that it's something you need to worry much about at this point in your hobby, but different styles of props load the engine differently. APC and the Master Airscrew "K series" props have more blade area and so require more torque to turn in a given size. On the low end is the MAS Scimitar props with their thin blades that will really let an engine unwind.

AllModesR/C

I want to ask a question about the Hobbico trainer. When I roll for takeoff at full throttle the plane will not rotate on its own even when it is rolling as fast as it can on the ground. I always have to apply up elevator to get it to lift off. Second thing is after lift off it wants to both yaw and bank to the left for some reason. Almost to the point of a stall but it always seems to gain enough airspeed and climb to an acceptable altitude. Once it reaches level flight it seems to fly fine. Just upon takeoff it does this. Any ideas? And keep in mind I am only applying up elevator at takeoff, no aileron or rudder input.

52larry52

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Are you flying off a grass runway? If so, is the grass a little on the long side and the plane is fighting like mad to get through it and gain take off speed? If you answered "yes" to these two questions then I would suggest; #1 a slightly larger and higher output engine. A GP42 is at the bottom end if engines for that plane, an OS 46 AX would be a night and day difference on take off.; #2 along with the engine up grade get the plane to sit up a little higher off the ground so you can fit an 11x6 prop for the new engine. Maybe a higher sitting dural type main gear with a longer nose gear strut, and larger diameter tires to roll better in the grass. I have seen modestly powered trainers that would not take off because of the extra drag of the grass on the landing gear and the slowing of the engine RPM because it was cutting the grass for the grounds keeper. If you are flying off a paved runway, ignore what I just said. Maybe a little up elevator trim would help but it still sounds like you are almost in a stall at lift off.

Tom Nied

I don't agree with #1, a TT GP 42 is good enough for a trainer, setup right with the high needle set correctly. I had an Avistar with a TT GP 42 on it and it flew fine. I did go to two sizes larger on the wheels and yes, it's helps to have it rolling down the runway either level or just slightly nose up. So I do agree with #2. Up in the air, it was a blast.

AllModesR/C

Larry the runway is paved. If I was taking off from grass I don't think the plane would roll faster than a brisk jog. And just for comparison the Nexstar trainer on my flight sim 7.5 will rotate on its own very easily. My real life plane not so much.

Also just out of curiosity, can you hand launch a 40 size trainer?

52larry52

My Feedback: (1)

Tom, I didn't say "the TT GP42 isn't good enough for a trainer". The OP said it flys fine once it is in the air and I don't doubt that. I thought that IF, key word IF, if the drag from slightly long or thick grass were slowing the plane and engine RPM down on take off roll, it could be overcome with more engine. If the airplane won't take off safely, not in a stall, that needs to be addressed. Bringing your own grass mower and cutting the grass would also "fix" the problem, If grass drag is an issue. I don't know if it is. Let's see what the OP says about his field conditions. Nearby we have a non AMA flying field in a county park that from time to time the park ranger has not stayed up with keeping the runway nicely cut, and we have had Hobbico Superstar trainers with an OS 40LA that were unable to achieve takeoff speed. Same plane with just a 46LA up grade takes off. Another place I sometimes fly at is a sod farm. It is always well cut but some of the grass there is so thick that even some larger planes struggle getting thru it on takeoff. Hay, the OP might be flying off a paved runway and then as I said ignore all the grass drag stuff.

52larry52

My Feedback: (1)

Allmodes, Ok you just completely "blew up" my theory! Your flying off pavement so now I agree with Tom that the GP42 should be ok for power. Now, next question is what prop size and pitch are you using? Have you tried some others with the same take off results? Are you sure you have the engine properly peaked with the needle valve adjustment?

52larry52

My Feedback: (1)

Oh, your other question...I don't know if you could hand launch a 40 size trainer, I have never had the guts (or need) to try that. If you were to try that it would be a 2 man operation and even when I have done that with park flyer electrics my launcher person always seem to toss it up into a stall not level so the plane can gain airspeed. You would need a good trained launcher person and a willingness to maybe damage your plane to try it. I WOULDN'T DO IT with my plane! I think we need to fix the takeoff problem, not damage the plane and create additional problems.