Have built a T/F Spitfire O.S.91 4S,Robart Retracts,Monokote covering,JR Radio. After balancing it weights in at 10 and 1/2 pounds. Is this to much and also had to put 21 OZ of weight in cowl to get it to balance.Have checked the balance point so many times to see if it was right I can now do it in my sleep.This kit has turned out very nice and hate to screw it up on a balance and weight problem.And if it is to tail heavy what can I do now?Hope someone has built this kit and has some answers. Thanks Guys. Frank

Wing area 687 sqin TF spec's 7.5 to 8.5 pounds
Wing loading is 25-28.5 oz per sqft
From Tower site

687 sqin /144 = 4.77 sqft
10.5 lbs x 16oz = 168 oz

168 oz/ 4.77 sqft = 35.22 oz per sqft wing loading

You are very heavy it will fly , but in some very skilled hands that way and be pretty hard on the gear.


What did you cover with? I know that kit box weights are off and it's hard to keep them to the high end of the spec'd weight.
But two Lbs more on a 64" wing is alot are there any extra Dodads you can leave out that you don't realy need?

Sounds like alot of work but if you can move all and every thing as far forward as you can to get rid of that 21oz dead weight.
Battery servos RX all of it if you can! use mini servos for throttle and retract switch

Den

Thanks Den that what it is looking like I have to do.Can gluing to heavy in the tail section do this? I called top flite he said 10 to 12 OZ max on noise weight.I covered it with monocote.Will play with it for awhile and see what happens.

[QUOTE]Originally posted by FrankRC1
Can gluing to heavy in the tail section do this?
Yup
I'll assume that the air tank is behind the wing in the fuse
that doesn't help either but not much you can do about that one.

I know they are tight inside but it well wourth the extra engineering to get it all forward as possible.


Good luck

Den

Your Spit does sound heavy. I am just putting the primer on mine, and hope to have it completed in March.

Prior to glassing and painting, I installed all my components and weighed the plane. I was under 8 lbs! Balance point was right on, with no added nose weight. I am using an OS 61 FX. After finishing with .5 oz cloth, resin and paint, I know I will have to add some nose weight, but expect (hopefully!) under 8 oz. My projected weight is under 9 lbs, targeting 8.5, just depends on the amount of nose weight needed. I also have the Robart retracts and the cockpit kit, but did not install flaps.

I am currently flying the TF FW190, all up weight of 9.1 lbs. I have retracts, cockpit kit, and painted finish on it as well. I have read reviews of this plane at almost 11 lbs!

I am surprised to see other modelers TF kits come out so heavy. With mine, they have all been in the TF specs (I have built 3). I did no mods to my FW190, but did cut extra lighening holes in some tail pieces on the Spit, since it comes out tail heavy. I do take care to build light, limit glue, make sure pieces fit, and use only light wood in the tail, etc. If a kit piece feels heavy, I replace it. The kind of filler makes a lot of difference as well. I take pains to insure my pained finishes are light, and I believe my paint jobs add very little more weight than a film covering would.

On the bright side, I read a review of the Spit at 10+ lbs, and the reviewer said it flew great!

Cal

Have made some adjustments on servos,battery pack,and moved them forward and lightened it up in the tail.I think it will be better.Do you use thin CA more than Med CA?

What do you weigh your planes with?

Regarding the CA, I used about the same amount of thin and medium, just depended on the application. I also used some thick in a few places. Of course, I use epoxy on the firewall, wing bolt blocks, stab attachment, etc. The sheeting was joined with sandable "Elmers style" wood glue. Top Flite seems to overbuild to protect themselves, so there are opportunities to lighten. An example was to apply an Epoxy Fillet inside the stab cradles. If you had a good fit and glue application to begin with, this is not necessary and only adds weight. I added extra lightening holes in the stab saddle, and all fin ribs. I used the lightest wood in the kit for the tail sheeting, and replaced some of the other tail wood and other wood with lighter pieces. Use only lightweight "spackle" type filler under your finish, not bondo or epoxy with microballoons unless strength is needed.

I weigh my planes with a fish scale, bought at K-mart or similar. I checked it accuracy by weighing a barbel weight, and found it measures 10 lbs right on. The scale runs from 0 to 22 lbs.

Do you have a pic of your Spit? I would like to see how you came out,

Cal

ps Here is a pic of my FW190. Flies great, very stable and easy to fly.

Will get a photo and post it.That FW190 is very impressive my spit is not into the amount of detail that you are doing.But hope to be as time goes along.Thank You for the advice Cal.Trying to get advise from club members around here is sometimes hard.It is like they want to keep there building knowledge to themselves.Thanks again Frank

Cal this is my T/F Spitfire

Good job! I cannot wait to get mine all together. I sanded the primer on the wing today, and am getting ready to install the cockpit kit. Then I can prime the fuse and start the color coats.

What pilot did you use?

Cal

I used a half bust pilot Hanger 9 1/7 scale.With you using a full cockpit you will us a full size pilot.The top flight scale pilot is nice with your skill you should have no problem painting him up. How long have you been building?

I still haven't decided on a pilot yet, and may just leave the cockpit empty. The details show better that way, although a pilot does look better with those low, slow fly-byes. If I keep my speed up maybe no one will notice

I have been building off and on for about 12 years. I took a few years off of R/C in the middle due to job demands and relocation.

I have built approx. 20 planes, 3 of them being Top Flite warbirds (P-47, FW190, Spit). I have the Yellow Aircraft Zero ready to fly this season, that should be interesting. I am also flying the TF Contender, a nice easy fun change of pace.

Cal

Cal what do you think about T/F P-51 1/7 Scale and P-40 Kits?I was looking ahead to my next project. Thank For your Time, Frank

Frank:

I do not have any first-hand experience with either kit. A fellow club member built the P-51, and did not have a lot of success. The kit looked good, except for the non-scale nose line. He ripped the landing gear out several times, and advised anyone who built one to reinforce the retract mounts. He never seemed to be comfortable flying the plane.

The P-40 has a reputation of being one of the hardest Top Flite warbirds to fly. Not as friendly on the ground, and stalls easier.

Keep in mind these are just things I have heard, not first hand experience.

Most people will agree that the P-47, FW190 D9, and the Spit all fly well, with the P-47 and the FW190 the best. I can say that the FW190 D9, in my opinion, is the easiest to fly of any warbird I own as it is so stable with moments similar to a pattern plane. I have never heard anything bad about the P-47 either, and mine flew great (sold it several years back before I relocated).

I hope what others have said about the Spit is true!

Hope this helps,

Cal

Frank:

One more thing:

I have decided to build the Ziroli 70" P-47 as my next project. I received the plans last week, and have the wood on order. The Ziroli P-47 is also 1/7 scale, and will go well with my FW190 and Spit.

It is amazing how big the P-47 really was! Even though the Spit and the P-47 are both 1/7 scale, the Jug is a much bigger plane, especially the Fuse. I rolled the plans out and was taken back by how big the fuse formers are. I have read lots of info about WWII fighters, and have visited the AF Museum many times looking at the various fighters, but until you see the Jug sitting next to a petite Spit, P-39, or P-51 you just don't realize how big it really is.

Gotta finish my Spit so I can get started.......

Cal

Ziroli is that the type of kit that you have to cut all the parts? I mean nothing is Di-Cut it comes as plans and wood.

Frank:

That is one way to do it, you could cut all the parts yourself. I ordered a cut kit from one of the kit cutters, since I don't have the proper tools (or patience!) to cut all the parts myself. The kit cutters will cut all formers, ribs, etc and also provide all the sheeting and stick stock needed for the kit. Basically, you end up with a Top Flite warbird kit (but with better cut parts, not die-cut) without hardware and the detailed, pictured instruction book. The Ziroli instructions are a short list of steps, without pictures, to guide you through the construction.

The construction techniques are not any more difficult, but you do have to plan your own hardware hookups, etc, so some experience in kit building or help would be required for beginners.

I should not have ordered my plans so early, I am dreaming about what I am going to do to my P-47 before my spit is finished!

Cal

Hope you did mind if I e-mail you from time to time.I really appreciate your help.

Frank:

No problem. These forums are great, I have learned SO MUCH from others here. If there is something I can pass along I will gladly do it.

Good luck with your Spit! Let me know how it flies.

Cal

The TF P-40 flies fine, you just have to keep it around 10 #
Mine is 10.5 and flyys fairly well., Your spit should be great at 10#
check out the warbirds forum. there is a ton of good info in that forum specific to the TF kits in general