Springbok Flyer

Thanks Dave.

izzy

This is my first jet. So story to be told

Test flight went well. Had one of our local experts Ofir Babish test her and she flys like she's on rails
Second flight I held her in the air and was on a high. So after Ofir landed her. I took my try at takeoff
Let me tell you I F!*k&d up the takeoff pretty bad and she snapped on me. Mainly because I freezed when she ran side ways and pulled full up. So if your are new. Take into account jets weigh a lot and need airspeed !! Ask me now how I know
Damages included broken V fin and fuse broken up front and cracked mid fuse
Two months down the road and all fixed like new. Hardly notice she was broken. Almost no weight difference
Test by Ofir again and this time after I leant my lesson Takeoff was pretty good
Landings were ok but i need to learn power management to get her to land smoothly
Using flaps as per manual but she drops pretty quick if power not left on. How much power do I need to keep till touchdown
Lastly the stock wheels don't grip to well on Tarmac. Has anyone changed these ??
Hope my story helps someone.

BlueBus320

My Feedback: (57)

Sorry to hear about the 1st mishap, I'm sure that hurt with such a pretty model, & congrats on your successful re-maiden[8D]

mitchilito

My Feedback: (7)

Seems to be a lot of major flash repair going on lately. Ask ME how I know
http://www.rcuniverse.com/forum/m_11...m.htm#11479298

paulhat

Hi Izzy

Good on you for getting her back in the air.

The only bit I wanted to comment on was "How much power do I need to keep till touchdown "

I guess there are many ways to land the UF but for me I glide the last 100 meters or so with no throttle (engine still running but stick back).
We don't get alot of wind here so hardly any throttle is needed for the final leg.
If the wind was up I would use more throttle to get it home.
Basically you dont need much throttle to perch it unless you have a strong headwind.

Would be interesting to hear others thoughts!!

Regards,

Paul.

Dave Wilshere

Good on you for getting her back in the air.

The only bit I wanted to comment on was ''How much power do I need to keep till touchdown ''

I guess there are many ways to land the UF but for me I glide the last 100 meters or so with no throttle (engine still running but stick back).
We don't get alot of wind here so hardly any throttle is needed for the final leg.
If the wind was up I would use more throttle to get it home.
Basically you dont need much throttle to perch it unless you have a strong headwind.

Would be interesting to hear others thoughts!!

Regards,

Paul.

[/quote]

Paul

So many different scenarios, wind conditions, flap angles and "other" drag methods. A few degrees difference Flap makes a big drag/lift difference. I have quite a bit of flap (as seen in many shots of my Green UF) and if its calm I'm reducing power and descending constantly from down wind in front of the pilots box (so the height you start at affects this!) But like you in calm conditions I'm off the power a long time before touchdown-But if you are flying from a short strip its better to have the turbine spinning above idle, so you have a response when needed. I this case I'll aim for a touch down point 50m before the strip to allow a flat final approach with a little power still available. You need to be able to judge when to chop the power.
In wind I will carry more power, but again descend from down-wind in front of me and just aim for the touch down point knowing I won't be carrying much ground speed.

Its best if you don't have a tonne of experience with lots of different aeroplanes to shoot some practice approaches from half way through the tank and got used to how an aeroplane handles dirty.

Dw

izzy

Friday had me witness what can almost happen if we're not careful
Fellow modeler was setting up his smoke system and suddenly plane caught on fire. Luckily extinguisher was on hand and quick thinking and action saved the model with minor damage to some tubing
This model had an access hatch to see motor while trying to set up the smoke
What I am now asking is how can I avoid this if our flashes don't have an access hatch to see while running as we can't see inside what's going on.
I am using a fully enclosed bypass and with wing in place would probably not know till its too late
Any comments??

Also reasoning question about better "grip" tyres as the stock skid on tarmac or while braking

TUMBLER

My Feedback: (13)

Was hoping to fly mine tomorrow but after 3 hours trying to get the flaps to work I burned up a servo and I am done. I have tried 8411s and hs 5645s. Tw problem I have is that they will not stop buzzing at full up position and don't stop buzzing until there is a big gap between the leading edge of the flay and trailing edge of the wing so then there is just a ton of slop.
Any ideas?
How long should the servo arm be?
What should the position of the arm look like at full up, mid flap, and full flap.

Thanks!
Brian

mitchilito

My Feedback: (7)

They are going to buzz at full up. Digital servos are going to do that. The trick is to limit the amount of bind to the minimum. I dial in the up travel while wiggling the flap. I settle for just a slight spongyness in full up - indicating a minimum of binding. But they are going to buzz at this point.

I'm using the factory recommended linkage lengths and 8411 servos with Dubro heavy duty horns. I feel your pain: setting up the flaps is almost as bad as setting up the retracts. Almost.

TUMBLER

My Feedback: (13)

Thanks for the reply. Glad to hear I am not the only one. I have done internal linkages for flaps but the servo was attached to the top wing skin and was waaaay easier. My servos don't have that typical digital chatter.....they are definitely buzzing like they are under a load. Is that what you guys are experiencing? It starts off bad then I back it down and it is still buzzing but not as bad then goes to the regular chattering sound but at that point there is about a 3/16 gap between the flap and trailing edge of the wing and its real sloppy.

BlueBus320

My Feedback: (57)

Hey Brian, do you use a load tester while setting up?

TUMBLER

My Feedback: (13)

No, have always just gone by sound. If it buzzes I don't fly it.

izzy

Brian. Not to be an expert. But I suffered the same and got me confused to death
At the end I was told that when she flys the flaps are "forced level" from wind resistance
And that its ok
I set mine up so that flap just reaches the level when full up and might be a touch down as there is minor slop
The Buzzing doesn't go away but if you just lightly pull on flap up with slight finger touch the buzzing is relieved
Hope this makes sense

I really want to thank all the people here on RCU and especially Dave W for there input on this thread as without it I would not have completed my model
This thread is great and filled with lots of info
And it's so great to have others want to help

Dave Wilshere

As the guys say, you do get some buzzing as the weight of the flap applies a load and the servo works to hold that. I set up my flaps with the wing vertical in a K&S (orange) model stand.
Things to check are that the flap horn is not rubbing on the top wing skin when the flap closes. (without the linkages connected does the flap smoothly close with no resistance) Then the same with the clevis installed.

Then check the 3mm rod does not rub on the structure either.

There will always be a tone with the linkage connected, knowing what is OK or not takes experience of the servos you are using. H9 make a nifty servo current reader (HAN172 from memory) plug this between servo and Rx to see how the current varies, new control horns will bed in as the pin on the clevis polishes the hole, the load will reduce when this happens.

I set my servo horn position and approx travels before placing the servo cover plate in position, I aim for the servo arm to point at the flap control horn position when at full flap. This way the max surface load is off the servo. The up position is where it ends up. I then adjust the rod length to give me full flap (with the arm pointing at the flap horn) Use the flap system to adjust the take off and up flap position.

Izzy, we have no issues with tyre grip, but temp and surface will affect this. Are you sure your wheel tracking is straight or tint bit toe in.

Dave

izzy

Toe in. I'll check tonight. Do I need or not need toe in ?
Thanks again Dave

Dave Wilshere

A tiny bit of toe in is good for good ground handling. I put a stick across the wheel to lengthen the sighting line

Dave

MAXIAN

My Feedback: (2)

Hi, there is someone that have a wing and stabilator for a blue angels Flash?
Not the ultraflash version, but the first.
Someone that changed to ultraflash version and have old wing.

Thank you

spike5150

Still in in the early stages of my UF build, but I at least got to see one fly again this past weekend at my local field.

ons_pk

Hi Dave

In post 61. I notice your engine looks like it is installed a bit off center. Is that a right thrust angle?

The screws on the bracket is not on the same spot L/R

Thanks

Dave Wilshere

No, that was my specially selected first batch kit with twisted wood work! The wood formers slipped in bonding and I had to adjust everything to get it straight.
I had to fiddle a few things on mine to get things in, so ignore positions.

Changing the angle on a turbine blowing down a tube makes little difference, its the tailpipe alignment that dictates things.

Dw

ons_pk

Thanks Dave,

Is there a quick way to check that the wood work is properly aligned and straight.

OS

Dave Wilshere

O

You can put a straight edge across the back edge of the wing seat and measure, but its not critical. long as you measure from the turbine to the fuselage sides and centre that you are good to go.

D

TUMBLER

My Feedback: (13)

Can someone tell me where I can find instructions for the all in one brake/retract valve. I ought my airframe second hand.
Thanks!
Brian

Dave Wilshere

Not sure if this will come out!

TUMBLER

My Feedback: (13)

Well I found that online but mine is already all plumbed. I am just trying to figure out ow it works. I am assuming I mix the gear to another channel on the slider switch and then limit the travel when the mix is off so the brakes don't engage and then when the mix is on the travel allows them to engage. Right? I switched to Futaba for this jet and having trouble getting the mix to work.