Balancing of TF Spitfire Prototype
 

I am going to post this question here since my first two attempts to email top-flite direct resulted in no response. Anyway, I am trying to make an engine decision on this kit and would like to know if any weight was needed to balance it properly and where. I would like to incorporate that info into my decision. I have a Saito 82, Saito 91 and a .61 OS on hand. From what I have read and heard, it builds a little tail heavy so I was wondering how the prototype came out since the OS .61 two stroke was used. I believe there have been some changes to the kit to lighten the tail since the prototype but I am still curious how it originally came out. Otherwise, the manual and kit look great and I am ready to get it start over the holidays.

Thanks in advance for the help. Keep the kits coming!

RE: Balancing of TF Spitfire Prototype
 

Rustypep,

I built this excellent kit in 1998 and it was one of the best flying models I ever had. I started out with the O.S. 61 - I still have the header pipe and special muffler for it, if you are interested. While not a light builder she was indeed tail heavy, big time. I added at least 1-1/2lbs to the nose to get her to balance. The maiden flight was excellent, trims were good and she handled well. I lost her on landing, keep the speed up! Superficial damage, but knowing that I wanted to make it more scale sounding, I installed an O.S. 91 Surpass. This reduced the amount of weight to a little more than a pound! So, my all up weight as this ship became familiar and ran the circuit as an everyday flier was 11lbs, 8oz.

The trick was getting her off the ground. This was always the case. Noseovers were a common occurrence and you had to watch the wingtips on takeoffs. The gear tracks very narrow and rough ground will cost you. This is also true on landing. For many years I never had one landing that didn't end up on the nose. I found later in her life that setting the elevator to maximum throws - even more than the manual recommended was a heck of a good idea. You had way more elevator than you needed (watch out), but it got you off the ground. Once you left the ground, you had the radio programmed with dual rates or equivalent and you would flip them on and the elevator would return to normal throws. Add'l rates for smaller throws I never found necessary as long as you used significant exponential.

At any rate, she came to and end on a particularly hard landing and I decided to retire her. I've since moved to another area in Michigan and now fly giant scale - my .60 sized days are over and I only have the P-51 Top Flite Gold Edition left. But in summary:
1). Put the biggest (i.e. Heaviest) engine in that you can. The two stroke, with the scale muffler looked really scale and was hidden well. The four-stroke? Well, you are going to have to think about that one. Hello, www.keleocreations.com? It all depends on where you want to go.
2). The throws on the elevator will get you much, much better ground handling. All those nose overs were frustrating and were simply a result of the placement of the gear, which were, simply, a compromise. The CG was dead on. You might have a close look at using a pump and altering fuel tank placement too, but I doubt that can happen. Using S-48 (regular) sized servos, that was one of the tightest radio installs I've ever seen! So you're pretty much stuck following the manual. Don't forget to balance the model with the gear up!!!

Anything else you need, just drop me a line.

I looked for some pictures of my Spit, but I didn't have any handy.

Let me know if you choose the two stroke powerplant, I've got the muffler and the header for it!!!

RE: Balancing of TF Spitfire Prototype
 

Rosster,

Thanks for the feedback. I have been following a lot of the TF builds including Tubigs so I am adding up a lot of ideas. I just ordered some new 4-6lb sheeting to try and keep the weight down and I am planning to glass and would like to keep it around 10 pounds but ideally less. The prototype was 9.5 pounds but I think it was monokoted. I am thinking about using seperate servos for the flaps and using the space in the center section to relocate the air tank and maybe the valve/servo setup. This would also simply the air system setup. I would just need to connect the servo for the retract value when I put it together at the field along with the leads for the ailerons and flaps. I also like the idea of of a few less links in the air system which usually means less chance for failure (KISS principal).

I am afraid the 82 won't be enough weight as you mentioned so I am thinking the 91 may be better. The 82 fits better in the cowl and I did have Keleo exhuasts in the back of my mind...haha. The 82 gives more room in the cowl for that but it may be possible with the 91 as well but only if Keleo will build one for this size ship. I haven't called him yet. I do like this idea though because I could then think about putting the battery where their special muffler is mounted and push more weight forward. A scale muffler would also push more weight forward, which could be the difference between a 10 and 11 pound plane and more enjoyable landings. Gotta decide on an engine first but you are reading my mind. I may talk with you about your engine/header/muffler if I go that route but I like the sound of a four stoke. I already have the robart retracts and struts, etc. and have docs on the way from Banka so it is coming together. I love the Spit and if I can build it light I think it will be a great first warbird. I have their T-34 kit and that will be next and then maybe something larger after that. Still a lot to learn. Thanks!

RE: Balancing of TF Spitfire Prototype
 

rustypep, i'm looking at 10-10.5lbs. for my build with an OS91FS. i would agree with using the heaviest engine in class that you can get and use a large battery pack up front (might as well make the weight useful right?). i'm within several work days of finishing this with some minor painting, a little weathering and the clear coat to add to finish it up. unfortunately, this isn't going to happen now until the end of january. but then comes the all important balancing act. i'm sure you don't want to wait that long so i'll just say that i've never heard or read of any TF spit coming in nose heavy and i doubt mine will be any exception even though i did as much as i could to keep the tail light. good luck and happy building!

RE: Balancing of TF Spitfire Prototype
 

Tubig.

I have really enjoyed your build and will be borrowing a few of your ideas along with a few others from some other builds. 10-10.5 pounds with the detail you added would be excellent and hard to do lighter. You Spit is looking great. If I am lucky I will end up in the same weight range with close to the same detail. I am going to start on the tail over the holidays but I am still getting my docs together and making a decision on color. Both options have the same tail setup so I can at least start on that. I did order some 4-6 pound balse sheet to replace the sheeting in the tail, which will cut a little more weight but I probably won't go any further than that in replacing wood. The engine decision really comes at the end of the fuselage build so I still have some time to make a decision and see how yours comes out. My building board is waiting for me to start pushing some pins. Keep it going and Merry Christmas.