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Aug 26, 2011, 11:25 AM
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slcrcflyer's Avatar
Discussion

Grob 103C escale/Hobby Lobby



Just put the first test flight on the grob 103c from hobby lobby, all I have to say is save your money! This was the biggest waste of $600+ I have ever spent.

Problems are as follows:

Missing parts.

Horrible stall speed matter where the CG is even with the turbulators.

45 amp draw! That its the max draw for the ESC on one climb of 50 seconds the motor was blistering hot!

The plane was porpoising during level flight [first time experiencing that in 25 years of RC flight.]

Do any of you wonder why the demo video doesn't show the landing? I speculate it's because there wasn't a landing [crash!]

Don't make the same mistake as me. I now know why nice scale sail planes are in the $700+ range. You get what you pay for.
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Aug 26, 2011, 02:14 PM
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Joespeeder's Avatar
Hi slcrcflyer,

I have one of these in the box and hoped to have it done by the end of next month.

I read the other thread on this plane with interest as they had teething issues but seemed to get things worked out.

https://www.rcgroups.com/forums/show....php?t=1461763

From your post it sounds like you played with the CG. Can you give any insight as to where you ended up. Do you think it's an incidence problem?

What was missing?

I was hoping for an easy no brainier to fly in a pre packaged format. I was thinking of getting the Fox if this worked out.

Thanks for the heads up.

Joe
Aug 29, 2011, 11:14 AM
Registered User
Well this is not encouraging. I have one which is about 75% complete and I was hoping to maiden it this weekend. I havenít noticed any missing parts on my build, so I havenít had that problem.

Funny, I did wonder why they didnít show a landing on the demo video.

Do you have the spoilers in the wings? I am wondering if not putting them in would help with the normal flight characteristics. Does it even need them?

I have been following most of the directions from the espritmodel.com manual rather than the manual supplied by hobby-lobby. I did notice that the espritmodel.com manual has the prop at 13x6 rather than the prop that came from hobby-lobby which is 14x6. I havenít tested the motor yet but I am curious about the draw now. Are you running a separate BEC or receiver battery pack?

I am also curious about your CG location. Writing this post and looking in the two manuals I notice a large discrepancy between the CG location and control throws. The hobby-lobby manual says 70mm from leading edge, which was where I was going to start. Except the espritmodel.com manual says 45mm to 50mm, which I think makes more sense. The control throws are very different as well, what do you have your throws set too?

I am hoping we can get this plane to fly well, I was really looking forward to it.

Kevin
Aug 29, 2011, 12:30 PM
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Joespeeder's Avatar
Hi kstakem,

Interesting about the two manuals. Please post pics and any video you might get as you maiden your Grob.

I will print off the Esprit Models manual and follow both as I build. When it's time I'll do some CG calc's to reference.

Maybe Google Topmodel Grob 103c to see if there are any UK builds of this model?

If I turn anything up I'll post links here.

Joe
Aug 29, 2011, 01:28 PM
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Joespeeder's Avatar
Found this....

http://translate.google.com/translat...%26prmd%3Divns




Grob G103 Twin III Acro Key Chain Cam 808 embarquée (14 min 45 sec)
!


Grob G103C Twin Acro (3 min 55 sec)




Joe
Aug 29, 2011, 02:18 PM
Registered User
Nice video's, seems to fly well in them. Hard to tell how it thermals, but didn't see the porpoising.
Sep 07, 2011, 06:40 PM
Registered User
Quote:
Originally Posted by Joespeeder
Hi slcrcflyer,

I have one of these in the box and hoped to have it done by the end of next month.

I read the other thread on this plane with interest as they had teething issues but seemed to get things worked out.

https://www.rcgroups.com/forums/show....php?t=1461763

From your post it sounds like you played with the CG. Can you give any insight as to where you ended up. Do you think it's an incidence problem?

What was missing?

I was hoping for an easy no brainier to fly in a pre packaged format. I was thinking of getting the Fox if this worked out.

Thanks for the heads up.

Joe
Hi Joe,
I am the the fellow who started the thread you linked above.
Just to let you know and give others a heads up the teething issues have not been solved. Stay tuned or post up your findings.
Sep 08, 2011, 06:38 AM
Registered User
I just started building my Grob and I'm disappointed to read about the tip stalling issues. Years ago I used to fly slope planes in California. I had a Bob Martin SR7 that had a nasty tip stall that would cause it to snap roll when slowing it down on final. The plans showed add flat angled tip plates to the wings which solved the problem. They looked similar to the plug in tips on the Grob only larger.

I wonder if bringing the plane in fast with the spoilers up will work?

I'm going to post a question on HobbyLobbys forum here regarding this

http://forums.hobby-lobby.com/viewtopic.php?f=25&t=2572
Sep 08, 2011, 06:58 AM
Registered User
RCForever. You are not to far from us. Maybe we could get together and compare notes. We fly near Forest City, NC.

Landing without tip stalling take about a 100 ft (maybe farther roll). We fly on a 3000 ft airstrip and need a large portion to land this plane.

Tip stalling is an issue but there are many others.
This is a list you may ask Hobby Lobby about. I would be interested in response.
!. Why do they not show landing video, is their plane still on one piece.
2. Why is the motors burning up. Prop to large?
3. No programming instructions with the ESC.
4. The instructions say not to use spoilers without separate BEC. Why did they not include in kit if required.
5.The addition of velcro on the tips indicate some one was aware of tip stall problem.

Good luck!. Post up your findings as Rick is still trying to get the bugs out.
Last edited by Tabasco; Sep 08, 2011 at 07:08 AM.
Sep 08, 2011, 12:46 PM
Registered User
Hi Tabasco,

You're not too far away. Maybe when I get mine done I'll come over.

I posted this thread on the RCG Hobby Lobby support forum. Here's what Jason from Hobby Lobby said re tip stalling

https://www.rcgroups.com/forums/show...2#post19260710
Sep 08, 2011, 12:52 PM
Registered User
Thanks for sharing the response from Jason.

It is runaround if you ask me. Did not address any of the issues rather than tip stall. BTW, on the video did you see ANY flying that was not wide open with motor. Anything less speed wise is a stall. That is not scale sailplane flying. They do not run the motor the whole time.

Ok, I'll stop ranting. Come on down sometime. Rick is flying his this PM. Maybe as I type. Hopefully he will post later.
Mike
Sep 08, 2011, 12:55 PM
Registered User
Hi all,

Unfortunately for me work and RL have been getting in the way a bit and I wasn't able to maiden mine last weekend. Of course the the rain is a issue as well .

I still need to finish putting in the elevator servo and secure the canopy with the latch. I can say the canopy and elevator servo are a PITA!! I ended up gluing the canopy in sections over the course of a week. Doing the sides first, using tape to keep them in place. Then the back and then the front. Tabasco suggestion, i believe, was accurate to cut larger than the lines and then just whittle it down to a good fit. I am not an expert builder by any means, so that alone took a few days to get a decent fit.

I am hoping to maiden this Sunday, so wish me luck!

My plans for the tip stalling are to use aileron differential like 2:1 and land with speed and use spoilers at the end. I am not sure the spoilers are really needed at all. I don't plan on putting on the turbulators, or what ever they are called unless I just can't get it fly right.

The glider does seem very heavy to me for such small / narrow wings, but I am new these types of planes.
Sep 08, 2011, 12:57 PM
Registered User
Jason's response seems valid, and is how i fly anyway so time will tell soon enough.

I agree with Tabasco's last post, I am assuming he is flying without the motor on.
Last edited by kstakem; Sep 08, 2011 at 01:57 PM.
Sep 08, 2011, 02:02 PM
Registered User
@Tabasco, what distance are you using for CG? The two manuals have very different CG settings.
Sep 09, 2011, 07:07 AM
Registered User
Quote:
Originally Posted by kstakem
@Tabasco, what distance are you using for CG? The two manuals have very different CG settings.
We used the method in the HL manual. Upside down at 70-80mm. The other manual call for 45-50 right side up. I do not know how these would compare something to check??? Appears to be a HUGH difference.

Be very careful on your maiden. This plane never stalls by dropping the nose. Always tip stalls.
We used Diff ailerons and tabulators as well.
I would only run engine short duration and check temp.
Also do not use spoilers if not using a separate BEC.
We have deduced that loss of control on 2 landings occued just after actuation of spoilers.

Looks like other have problems. This thread stated out with a bang then seemed to have died.
https://www.rcgroups.com/forums/show...7#post19268545
Last edited by Tabasco; Sep 09, 2011 at 07:20 AM.


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