RE: Maiden flight skymaster Gripen in Norway  
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All Forums >> RC Airplanes >> RC Jets >> RE: Maiden flight skymaster Gripen in Norway
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RE: Maiden flight skymaster Gripen in Norway - 8/18/2004 5:54 AM   
MNModels


 

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From: Oudtshoorn, SOUTH AFRICA
Status: offline 		Hi All,

Sorry to hear about your loss! We do not need things like this when we are spending so much money.

Well i have been flying jets for many years starting out with ducted fans and if you ask my humble opinion it sounds like you had a power to weight problem.

Nobody mentioned if there was a wind blowing. A 12 pound turbine in a slightly heavy airframe with 2KG of fuel on maiden making a downwind turn calls for a desaster even if you are the worlds no1 pilot. Not even to mention the drag on a delta wing. With ducted fans this was a continious problem cause ducted fans do not have the power turbines have.

This is just my 2 cents worth and i hope you do fly your Gripen soon. It is a great flying aeroplane.


Best regards

Morne Nortier
www.mnmodels.co.za
Exclusive distributer for Skymaster RC South Africa

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RE: Maiden flight skymaster Gripen in Norway - 8/18/2004 9:42 AM   
SAP_2000



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From: Stabekk, NORWAY
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quote:

ORIGINAL: AirPac Models1

Erik & Staale,

As I mentioned before, we are not questioning you building or flying capabilities.



No problem, Eric

Before the next try, the CG will be set to 100 mm's (back from LE @ the root.. )

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http://www.jetsofnorway.com

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RE: Maiden flight skymaster Gripen in Norway - 8/18/2004 10:41 PM   
rookie


 

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From: OsloNorway, NORWAY
Status: offline 		Hi Morne,
Nope. No wind,it was dead calm.The j600 r develops 14 pounds of thrust here in Norway due to air temp and being at sea level.
The Gripen has been advertised to fly with an 11 pound engine so 14 pounds should be enough.(i hope) It'll never be an eyegrabber performance wise but like you said its an expensive hobby.

Erik

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RE: Maiden flight skymaster Gripen in Norway - 8/19/2004 2:40 AM   
Aero65



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From: Honolulu, HI, USA
Status: offline 		Hello Erik

I will be able to get the settings that I have for my Gripen tonight. Sorry been very busy the last few nights. I also have a video of the prototype Gripen that has been repainted. The video is 40 MB in windows format. If you want I can post it on my www.hawaiijets.com website. Im posting it right now. It should be finished in a hour or 2.

Let me know if you need me to down size it.

http://www.hawaiijets.com/aircraft/Gripen/Gripen.htm Video is up J600R power.

< Message edited by Aero65 -- 8/18/2004 6:08:41 PM >

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RE: Maiden flight skymaster Gripen in Norway - 8/19/2004 6:00 PM   
rookie


 

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From: OsloNorway, NORWAY
Status: offline 		Thanks for the video clip.Nice to see that it flies good with the j 600 r.
I have now only to rewire the receiver and the bird is ready for test numbr 2.
C.G. is now sett at approx 10 cm from leading edge of wingroot.have to take it out side to measure it 100%.Not enough space in my hobby corner and right now its blowing and raining cats and dogs(+ the odd horse).
damage assesment: needs new paint job.2 broken plywood engine mounts.Need new engine hatch.I'll repair the old one and use it until i can get a new one from sky master. 2 small tears in the fuse where the servo cabels from the wing enters the fuse.7 small cracks in the fuse in noncritical posisions.
If it were'nt for the 5 foot high wheat field it flatspun into, i think the situation would have been different.
Amazingly the wing spar slots havent moved nor does the plywood formers they are attached to show any damage.
I'm looking forwards to gatting the details of your settups and control throws.

Best regards
Erik

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RE: Maiden flight skymaster Gripen in Norway - 8/19/2004 7:41 PM   
MNModels


 

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From: Oudtshoorn, SOUTH AFRICA
Status: offline 		Hi Erik,

Well that just eliminates just about everything! Guess Murphy paid you a visit....

Like Duke and all the others are saying - It is a well proven airframe and many of them are flying around the world with all kinds of turbines. And to date there were no problems.

Now we only need to see yours in the air.

Just one last thing : Did you check the CG upside down or right side up?

Good luck!

Morne Nortier
www.mnmodels.co.za
Exclusive distributer for Skymaster RC in South Africa

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RE: Maiden flight skymaster Gripen in Norway - 8/19/2004 9:12 PM   
Doug Cronkhite


 

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Status: offline 		To add a slightly different question..

Did you happen to check the thrust angle of the tailpipe? I initially had a lot of up thrust (causing an up elevator action) which could explain your pitch sensitivity.

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RE: Maiden flight skymaster Gripen in Norway - 8/19/2004 11:14 PM   
rookie


 

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From: OsloNorway, NORWAY
Status: offline 		Right side up.

Erik

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RE: Maiden flight skymaster Gripen in Norway - 8/19/2004 11:40 PM   
rookie


 

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From: OsloNorway, NORWAY
Status: offline 		Yes, i checked the thrust tube angle.During construction i noticed that the angle was inclined upwards.Since i had to make 2 mounting plates to fit the engine(the mounts that come with the engine were'nt wide enough) into the fuse, i shimmed the engine into a correct level to make the thrust tube come out horizontally with the airplane.I have had the opportunity to experiment with this on my Rookie and found that you had to angle the thrust pipe very aggressivly for it to make any difference.I also bear in mind that the pipe on the Rookie is much shorter than on the Gripen and thus not as effective.That's why i made sure that the pipe in the Gripen was sett at an correct horizontal angle to the airplane.No point in taking any chances.

Erik

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RE: Maiden flight skymaster Gripen in Norway - 8/20/2004 4:01 AM   
seanreit



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Status: offline 		Erik, maybe a dumb question, but any chance you put reverse expo in the radio instead of the alternative. This could easily explain over sensitivity when it wouldn't otherwise exist.

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RE: Maiden flight skymaster Gripen in Norway - 8/21/2004 11:03 AM   
Aero65



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From: Honolulu, HI, USA
Status: offline 		Hello Erik

My control throws were originaly setup as shown on the www.skymasterjet.com website. I have recently modified them a little ( I just reduced the candard throw ). Sorry I have been really running around the past few days. I will get them in the morning on Sat.

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RE: Maiden flight skymaster Gripen in Norway - 8/22/2004 12:05 AM   
Aero65



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From: Honolulu, HI, USA
Status: offline 		Hello Erik

Ok here it is

Elevator Low 12 mm up and down High 20 mm (measured at the trailing edge of the widest part of the elevon.)

Aileron Low 8.7 mm up and down High 11 mm (measured at the trailing edge of the widest part of the elevon.)

Canard 17.5 mm up and 10 mm (measured at the trailing edge of the widest part of the canard.)

Rudder 12 mm Low 20.5 mm Med 26 mm High. (measured at the trailing edge of the widest part of the rudder.)

This is for normal flight mode. For landing mode I just cut the candard throw in half for the up.

Good luck!

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RE: Maiden flight skymaster Gripen in Norway - 8/22/2004 7:37 AM   
MNModels


 

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From: Oudtshoorn, SOUTH AFRICA
Status: offline 		Hello Erik and Duke,

As far as i know when you check the CG of a high wing you check it right side up and if you check the CG of a low wing it is upside down!

I am not an expert but that was one of the first rules i took for granted starting out in this hobby.

The Gripen's CG according to me has to be taken upside down.

I would like to know the difference in mm from the root right side up and upside down. It is not the same!

Best regards

Morne

www.mnmodels.co.za
Exclusive distributer for Skymaster RC South Africa

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RE: Maiden flight skymaster Gripen in Norway - 8/23/2004 8:08 PM   
rookie


 

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From: OsloNorway, NORWAY
Status: offline 		Thanks Duke. I'll sett mine up the same way for the next maiden.

Erik

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RE: Maiden flight skymaster Gripen in Norway - 8/23/2004 8:09 PM   
rookie


 

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From: OsloNorway, NORWAY
Status: offline 		Hi Morne.

I'll check it out.

Erik

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RE: Maiden flight skymaster Gripen in Norway - 8/24/2004 12:00 AM   
Aero65



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Status: offline 		Hello Morne

I measure cg with the aircraft in the up position when it is possible. All Skymaster aircraft so far have been balanced this way as far as I know. If there would be any reason to invert the low wing aircraft, is that it is sometimes difficult to have the aircraft stay stable on the cg meter if most of the weight is above the pivot point of the cg measuring device. So for instance for the new Hawk, and the F-5 it might be much easier to balance them inverted.

I would not know why the balance point would change by inverting or putting the aircraft upright. Depending on the location of the pivot point along the long axis of the fuselage there should be a point perpendicular to the long axis that is the balance point.

If the aircraft wing has positive angle of attack the perpendicular line compared with the cord line of the wing will lay slightly back from vertical. This might make it appear to make the cg shift slightly fwd or back depending on whether it was upright or inverted.

Sorry for the long theory, your question of the difference really made me think for awhile.Hello Morne

I measure cg with the aircraft in the up position when it is possible. All Skymaster aircraft so far have been balanced this way as far as I know. If there would be any reason to invert the low wing aircraft, is that it is sometimes difficult to have the aircraft stay stable on the cg meter if most of the weight is above the pivot point of the cg measuring device. So for instance for the new Hawk, and the F-5 it might be much easier to balance them inverted.

I would not know why the balance point would change by inverting or putting the aircraft upright. Depending on the location of the pivot point along the long axis of the fuselage there should be a point perpendicular to the long axis that is the balance point.

If the aircraft wing has positive angle of attack the perpendicular line compared with the cord line of the wing will lay slightly back from vertical. This might make it appear to make the cg shift slightly fwd or back depending on whether it was upright or inverted.

Sorry for the long theory, your question of the difference really made me think for awhile.

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RE: Maiden flight skymaster Gripen in Norway - 8/24/2004 12:10 AM   
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Status: offline 		I have never balanced an airframe upside down, no matter where the wing is mounted on the fuse.

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RE: Maiden flight skymaster Gripen in Norway - 8/24/2004 1:17 AM   
seanreit



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Status: offline 		Wocketman told me that he only balances his jets upside down

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RE: Maiden flight skymaster Gripen in Norway - 8/24/2004 10:08 AM   
Aero65



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From: Honolulu, HI, USA
Status: offline 		Hello Erik

Here are some pictures from Sunday flying gripen's. I hope they give you inspiration to get your Gripen back into the air. I can call you if you want to discuss any of this further. I have a pc based phone that should only cost me a few cents a min. Let me know you can email me at duke@hawaiijets.com

My Wife took the pictures. Canon Digital Rebel L series 100-400 mm zoom.

Hmmm I uploaded normaly I wonder why these are supersized???

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< Message edited by Aero65 -- 8/24/2004 12:25:50 AM >

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