Peter A

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TOOD, great flight.
It seems that the Gripen needs to be yanked on take off, it does not look like a smooth transition form take off run to rotation. The video I saw at the Florida Jets of the Gripen did the same thing. Do you think this is typical of this plane?

The landing pitch control looks very effective, and the plane seems to sink with nose level attitude but holds in up attitude, it likes the nose up attitude and it does it with authority. Is this correct?

Mine is ready for the P120 (since this is the only turbine I have now) and I think I will dial it down to 112,000 rpm, not sure if smoke will fit since I have the ducting installed.

The flight looked really good, and the plane is very nice in the air.

Looking forward to the fine tuning steps.

Good luck
Peter

Airdoggy

Good flight. Based on what I saw, I think I will call you in a couple of days to remove me from the Bae Hawk list and order one of these. Thanks for the video and critique!

Tyler J.

lov2flyrc

My Feedback: (24)

Peter,
I think I over rotated in addition to having a tad of up trim already dialed in (had to put in about six clicks of down for level flight). Second flight takeoff was better but still a bit steep (will post some video of flight two if I find time). Did not really think about the rotation till you mentioned it, I will pay more attention to the flights later this week and see.
I spoke to Duke this evening, he did confirm that moving the CG forward to around 145mm should eliminate the pitching at slow speed and the tendency to drop a wing at stall. I will shift the CG forward 5mm for the next flights. Will be in touch with my final settings... P120 will be fine in the Gripen, probably over powered but thats how I like em Finding room for smoke will be a challenge though!
Tyler, no problem Give me a call

Basil, F18 is next on the list... when is D day? It is normal for canards to stall first, looks like Mario may be flaring too much [:@] any idea where his cg is? going to lake whales?

Anurag.... Your in line bud

Regards,
Todd

Peter A

My Feedback: (34)

Thanks Todd, replied to you by PM.

XCaliber

My Feedback: (104)

The pic showing my Gripen landing with nose high on the grass was the final stage of what happened earlier in the landing sequence.
On final I was coming in too fast & was very pitch sensitive (too much travel on conards),(conards on with gear down, off with gear up) on one of the pitch oscillations I hit the runway hard with the gear and bounced up, one of the main struts came off the trunion. I saw the strut with wheel hanging off so I made the instant desission to cut eng and land. Thats what you see in the pic.
This was my 11th flight. I am reducing the conards travel and keeping the C.G at 150mm for now.
I notice that at 145mm it was even faster on approches. I mit even try at 155-160mm.
Mario

basimpsn

My Feedback: (5)

I was trying for this weekend but my gear door cylinder start leaking. [:@] But as soon as that fix i will post pictures or video on its maiden flight.

Not sure of the C/G setting for Mario gripen?. I will try to get him to check out you threat on the gripen.

XCaliber

My Feedback: (104)

Basil.
I know what you mean on the gear door cylinder leaks.
I had the same headache when I installed the gear doors on the Gripen.
I trashed the ones that came with the Gripen & installed BVM cylinders and have not had anymore leak issues since.
Tod,
Nice video, I wish I had someone to take a video of a flight that would not loose the jet right after take off.
Mario

basimpsn

My Feedback: (5)

Hey Mario just talking about ya

I was watching todd video and saw the same dip when you were landing. Is this normal ?? I hope you can find some info here that can help. If its a problem. But overhaul nice flying at the meet . Glad you make it to our flying

Basil

XCaliber

My Feedback: (104)

Thanks Basil,
I enjoyed the event very much.
I guess the trike on landing the Gripen is learning to manage the speed on the approach as well as getting the C.G on your comfort zone and reducing the canard travel. And remember not to get distracted![:@]
Just have to go out there & put in as many flights as I can on this bird, practice makes perfect.[8D]
See ya soon at "The Aircraft Carrier" Markham Park.
Mario

basimpsn

My Feedback: (5)

3DHELINUT

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Dude, whats up with that big fat blubby lump leaning up against your plane ???? this is a family forum, and this is not the place to be showing inappropriate skin !!!!

Aero65

My Feedback: (2)

Todd your doing a great job with that Gripen. Can't wait to see what you can get the thing to do!

Hi Mario

We never flew the Gripen past 153 mm. The prototype would do some very interesting things at the aft cg. We were able to do a Cobra ( I was trying to get the Gear down and was at 75 ft ... Pucker factor lol ) maneuver. We also got it to spin, with recovery ( 1 turn then chickened out )

Im not sure what it will do at 160 mm. Might be fun ?? be careful and let me know what happens.

We have also found that when the CG is at 150 + when you throttle down and get slow the Gripen will tend towards a high aoa high drag approach as you slow down. You need to be ready to add power as the drag comes up. This seems to be more pronounced as the CG shifts aft as you would expect.

I also experienced pitch oscillations on landing with too much canard. Once I programed a flight mode to cut my canard throw to very little, like 10 mm up 5 mm down. I was able to make much more consistent landings.

Also for takeoff, on the ground you want the nose as high as you can get it. On my friend Tim's Gripen we added a 1/8" plate to move the nose gear down due to a steering servo clearance problem and it improved the takeoffs.

If you need to talk about it PM me and I can give you a call.

Lt. Dan

My Feedback: (21)

BAAAAAAAAAHAHAHAHAHAHAHAAAAAAAA!!!

I didn't notice that before. Woj likes to build in the buff!

basimpsn

My Feedback: (5)

The things you guys look for in a photo

XCaliber

My Feedback: (104)

Duke,
Thank you for your informative reply. I will keep in mind your C.G. suggestion.
Regards,
Mario

wojtek

My Feedback: (73)

I almost flew the Gripen yesterday, but engine and nose wheel problems prevented me from taking her up .. MY P80 was running hot at idle with a flame out the back, and my nose steering cable loosened up ... I did a few taxi tests up and down the runway to see how the plane would handle the grass. Acceleration was great on the grass, and the only thing to watch out for is the narrow gear stance .. the plane will tip onto the wing if turned too abruptly (why i have kept my missile rails off for now .. ) ... The SM brakes worked perfectly also .... Unfortunately i had to rip out my smoke system, it was leaking too much (old pressurized system, and in not willing to deal with it .. ) .... I already have the P80 back in the plane (John Redman at JC knew exactly what to recommend to fix my problem, it involved bending a needle in the oiler line under the case cover) I ran the engine up with no problems, and the plane is ready for its flight !!! I can't wait to take her up. I set my CG at 140, and set the throws as per Todd, with a little less on the ailerons. I also have a switch i can throw to cut the canard mix in 1/2. my dual rates are set to 100/70/60 on rudder , ail, and elevator ....



Wojtek

XCaliber

My Feedback: (104)

I put in 4 more none eventful flights, total of 15 on the Gripen.
This time C.G at 150mm ,lowered Dual rate and increased exponential. This gave me very predictable & concise landings.
The beast is been tamed

Falcon 64

Mine is ment to be airborne for the first time tomorow.
Thanks for your feedback to help the rest of us.

Gudmund

Peter A

My Feedback: (34)

XCaliber,

I am setting my Gripen-up. Can you please advise your throws and expenential settings?
Thanks
Peter

XCaliber

My Feedback: (104)

Yes,
ELEVONS/GEAR UP: 15MM UP,13MM DOWN ,55%DUAL RATE, 45% EXPO.
GEAR DOWN/LANDING: 18MM UP, 15MM DOWN, 65% D/R, 50% EXPO.
3-D : 22MM UP, 18MM DOWN, 75% D/R, 40% EXPO.

CANARDS/GEAR UP: OFF
GEAR DOWN/LANDING: 18MM UP, 9 MM DOWN
3D: 22MM UP, 11MM DOWN

AILERONS/GEAR UP: 9MM BOTH WAYS, 35% D/R, 45% EXPO.
GEAR DOWN: 11MM BOTH WAYS, 45% D/R, 50% EXPO.
3-D: 14MM BOTH WAYS, 55% D/R, 40 EXPO.
Remember, this is my confort zone.
Mario

Falcon 64

HOLY MOLLY.... What a ride!!

I had two flights on my JAS 39 today at Oppdal ........
Perfect conditions.

But, is this model really ment to be for a beginner in jets?
If i have even been close to the throws recommended at the Skymaster site, it would certainly been a new kit now.
My throws was very close to yours, Mario. The only difference is 10% less expo on the canard. But the canard is a major component in this model. And my question is( not to you Mario); Is this model really ment for the beginners in jets, and is it really ment to be flown at the adviced throws at the Skymaster site?
I can bet my F-16 and twin F-15 , if I had followed the advices there, it would all been totalized now.
And I don`t think it is because I`ve been flying model airplanes for thirty years.

I set the engine at idle on downwind leg, and the approach speed was close to 100 km when it passed me at final. I luckily managed to slow it down before touchdown, by working on the AOA/ engine.
To land it on CG at 148 mm, you have to either come on approach, five meters in altitude- 200 meters away, or stress the elevator combined with engine.
The first flight was the first alternative, The second landing was in scedule to the last one.
Definately, the best alternative was the last, but the most difficult one.

I`m next to speachless..
If this is a beginners jet, then the K-Fir and Mirage series is also!

I had 1mm slack in the elevons, I must get rid of it before the next ride.

Gudmund





Gudmund

XCaliber

My Feedback: (104)

Congratulations Gudmund[8D]
Mario

AirPac Models

Gudmund,

Congratulations on your maiden flight! Regarding your concern if the Gripen is ok for a beginner to fly; I think the location of the CG is the key. If you set up a 148mm for the CG it is good for advanced pilots like you and has a better maneuverability. As mentioned in the Skymaster website, 130mm (or less) is recommended for beginners because it makes the flight characteristics less sensitive. Also, it will allow the plane to land slower.

Falcon 64

Thanks, I`ll try it.
But the far to big throws on the canard should be adjusted in the guidance.
Thanks to such forums as here, one can always save ones butt, finding threads like this one.


Regards

Gudmund

SAP_2000

Got a SMS from Gudmund this afternoon, asking if I wanted to trade my Viper for his Gripen. So I called him asking what's up and he told me about the maiden today. His first words were something like ''this is the most touchy plane I have ever flown, and I can not believe they advertise this as a jet suitable for beginners'' He also told me that he felt very glad he had a plane to bring home in one piece.

I have read a bit about the Gripen here on RCU, and it seems like he is not alone to have a rather exciting maiden on this plane. There are also some people out there who have flown the Gripen and not experienced the problems mentioned above, so it has to be possible to make the Gripen more dockile by changing the CG and radio setup.

We talked a bit back and forward about his setup, and I suggested to try and move the CG one cm. forward and to flatten out the canard curve a bit around center stick to see if that would make it less pitch sensitive.

I have not flown the Gripen my self yet, but all the talk about it here on RCU have made me a bit curious about it. A fellow jet pilot here in Oslo has a Gripen, this is the same one that survived a flat spin with just minor damage into a corn field on the maiden. i have since then helped him out with a new radio setup and moved the CG forward. The guy who had previously set the plane up for him had not done his job at all... Elevator, aileron and canards all had too much throw and no expo. He had not even set up any low rates. This in combination with a CG rather on the tail heavy side was IMO the cause of the the flat spin.

I'll try to drag him along with me next weekend if the weather is OK to see for my self how the Gripen works with the new setup and CG. I will also be re-maidening my trusty ''old'' SM F-15 with a new scheme and a new potent power plant....