Sounds like a CG issue wouldn't you say?

Doc...

Hey phjoker . I hope this will help.

I bought the case from Wal-mart.

The first thing you need to do is build the support out of "L" shape metal or aluminum and Use the Glue & screw to hold it in place that will support the fake carbon plate which i bought from Dreamworks.

The Cooling Fan that i found from Fry's is reall cool it even shows temp. Shown as picture below...

I will post some more pictures......

Thank you

Nikki Ko

Hi,
You need to patient this. Great space saver as well. From start to finish, (everything included) what was your total cost?
Thanks,

Doc...

I think i spent about $450.00......

$45 Case,
$240 3 Chargers,
$60 Battery,
$13 power panel
$20 Fan
$50 Charging unit & Siwtch
$10 Voltage checker
....etc..

Thank you

Nikki Ko

CG is if anything slightly nose heavy. Seems more like a tail incidence issue. Strange both our models display the same effect. Will make some adjustments to the tail incidence.

Jim

Please advise on your tail incidence tests ASAP. I am just finishing mine and would like your views on this. Are you using any flap/ elevator mixing? The manual seems to suggest that you need some elevator trim when the flaps are being deployed but returning to no trim when flaps are fully deployed or have I msread this? Could the down elevator trim issue be resolved by adjusting the turbine thrustline? Bet your flying weather is better than ours.

Best regards

John

with partial flap (take off flap as some call it) most planes takes down trim as the nose will lift up, as you further drop the flap to the point it's more a speed brake the drag causes the nose to drop so you need up trim.

John. Keep everything as far forward as poss, or you may need weight in the nose. I have 2X5 cell nicads in the nose tray, a powerbox, turbine lipo & UAT on the equipment tray. Turbine pump, valves & ECU are just forward of the turbine. This is using a Wren Supersport & balance is fine without additional weight.
Get the flap/airbrake to go as near 90 degrees as poss.
I am using flap/elevator mixing. I needed about 8mm of elevator downtrim mixed in.
I already have a little downthrust on the turbine to avoid cooking the elevator.
The incidence thing is no big deal. I may set a little negative incidence later, just to see the effect.
I balanced mine on the carbon spar with no wings on.
Weather here is great. The heat of summer is gone. Temps around 82c & sunny every day.

Hello

Another word of caution. On my elevator the plywood/harwood base that is installed for extra support for the elevator horn was offset to one side. So if I was to use the supplied elevator horn method of 3mm screw, the 3mm screw would have been only in the balsa section and not in the hardwood section, giving much less stiffness to the setup and I did not want to fix the 3mm screw at an offset angle. Instead I used a graupner GFK horn that was installed in the harwood section together with ball linkages, which brings the pushrod in line with the servo.
Once again, this might be an isolated case.

P.S. I did install the servo covers correctly, as they are "handed".

Paul

If you read the post, earlier in this thread, from rcgypsy, you will see that he changed the incidence of the stab to correct the need for trim change. He also said he could have changed the thrust line of the engine.

He is a member of my RC club and an excellent builder. He has over 40 flights on the Sprint - most off of grass.

He has Scratch Built so many beautiful models over the years. We just attended a local Float Fly, yesterday, at a pond near our home. He brought his Spruce Goose, with 8 electric motors, that he has been flying for several years. It was flawless.. You may have seen his Red and Black Travel Air that has been featured in the NEAT Fair footage and in several model magazines.

He has dozens of exquisite scale RC models.

Hi John,
I have flown DVF's for about 10 years and believe it or not I never used flaps or did any mixing. I know that will change with my Sprint but here is the question. Would you suggest not using any mixing on the maiden flight? Additionally, since I've never really used mixing much except in Heli's, can I only assume that once the flaps are deployed causing the nose to drop, the mixing with the eleator up will stop the sudden drop? Is that about the right thinking?
Thanks for your help,

Doc...

Doc. The nose goes up when the flap/airbrake is deployed & requires some down elevator to compensate.

Hi Paul,
I had the same problem and mailed Alan Cardash to get another servo tray wwith the opening pointing to the opposite side. Alan told me that on the first batch they had this problem, but if I used the servo tray from the flap the error was corrected. Then, of course - I had to move the screw horn for the flap a bit to the other side to have the pusrod in line with the servo. This was possible because the plywood support in the flap was large enough. The extra hole was fixed with a patch of Oracover.

Pete

Hi,
Your right. I remember that on the sim..It would climb until the power really came down. I can see with flaps you can really fly it down to a landing instead of cutting off the power on the downwind leg or on final and just gliding in. I like the flap idea much better plus my DVR's only weighed about 11-13 lbs, not 18-22lbs. Thanks for head straightner.

Doc...

What is everyone using for air tanks? I only have the jumbo size from Robart, that does not fit. What size/brand is everyone using for the twin tanks, under the radio tray? Thanks.

Hi,

If you go to Dreamworks home page, it will give you an idea of the size. If you buy the Pro Link retract system complete which is designed for the Sprint, the cost is $825.00 complete with everything including both air tanks. You can order right from him or Patricia @ boomerang, USA in Texas. Shipping is only $10.00. The system is great and has been designed so you DON'T need to use any shims under the retracts. The fit is really great and the quality is super.
The system has everything you will need including both air gauges..Go check it out...

Doc...

But I already have everything retract-wise except the air tanks. Just wondering where I can get the right tanks, ready to go, before I start soldering on hair spray cans to make my own.

Yes I thought about ordering one but it would take too long to arrive. I installed the covers as indicated in the manual for all control surfaces. Yes If I had a cover facing the other direction I wouldnt have had a problem. I decided anyway that the GFK horn would be much stronger for the elevator given that it is not backed up with another servo or split elevators.

Paul

Hi Doc,

I ended up with a .030" shim under the front stab screws........I also had the model balanced right on the spar tube, without the outer pannels mounted,as suggested by Alan.
It took 5.75 ounces of lead in the very front of the nose (above the landing gear mount) to get it to balance that way........ but I would always start with it balanced there for the frist flights.

I have removed all the nose weight and added 1.5 ounces to the tail, There has been no need to change the stab incidense any further, and after 52 flights I am very pleased with how the model performs......not that it wasn't great all along, it's just very comfortable for me now.

I also have 30% down elevator mix ( about 3/16" of down) with 45 degrees of flap....and the model maintains level flight with the flaps down and slows down nicely.

Alan's Sprint design flies as well as any model I have flown in the 50 years I've been flying R/C........Do it like he says and you'll be a happy jet pilot.

Paul

Hi,
Call Todd at Dreamworks, 386-852-4793 after about 10:00am est and he will sell you just the tanks. They are Robart tank's and he will know the exact size for the Sprint. The price's run anywhere from $9.35 to about $13 and change. I believe he sells them for the same price as Robart does. Here is a direct link to his page that has the tanks.

http://www.dreamworksrc.com/catalog/...p?cPath=46_175

Doc...

Paul,

Thanks for advise. I'll "put in in the book". It won't be until late spring early summer before the 1st flight. Winter is already setting in this weekend. Can't wait!!! (not for winter)

Doc...

Yeah, I was gonna call Todd, but he only has the small and the large listed. I think these are the medium which appear to be discontinued. I'd better call him.

Hi Pete,
After reading what you had to say, I tried to make it fit but the hardwood insert is to far to the right. The servo mount for the flap is already installed but it wouldn't do any good to switch them. What I really need is another flap servo mount to correct the problem but, the hole in the side will be on the wrong side. Also, did you receive your yellow and white mounts without a clear coating on them? The red ones were just fine. I'll call Patricia on monday and have her get me a new mount for the elevator.

Doc...

Hi Doc,

Seems like every single Sprint vary some from the others??????

Today I finished mine - having a long winter ahead of me to get through....[]

PS:
I´ll check with my servo covers!

Pete

I'm planing on using JR 8611's on the rudders in the Sprint. Is this an over kill or should I use Mini's back there and if so, which ones?
Thanks,
Doc...