Ian.W

hi people, ive designed a speed plane, kinda based on the weston magnum. Im not expecting this to ever be built (im a bit like that, design loads not build allot) tho my school got a laser cutter so i may be able to!

So ive got a few questions:

1. im going to design it on an OS35fp, not a rocket motor but im just wanting this plne to be a bit of fun! what prop would i need for the most speed i can leach out of the motor.

2. the design of my palane is about 670mm wingspan and about 610mm langth. Wing rot chord is 220mm. is this too small?

3. whats a good fast wing section?

4. wot you think of it? will it fly?

Ian

Ian.W

sorry, fogot to post the pic

Cactus.

My Feedback: (1)

eddy eddy eddy, what are you on now??
the design looks like a Magnum thats been tied down and pulling at the strings, which is ok i spose, but a FP 35 isn't!
theres a guy down here with a GP 42 in a StarJet thats fastish, smooth and that would be about right for you too

if you must make a FP Magnum, work out the Maggers wing loading, scale your design to slightly better it so it's easier to fly.

the StarJet is a balsa version of a SAS glider btw.

orrrrrrr..... get a 40 sized Shrike....
Mini Rapier ( AKA Muts Nuts )
Diamond Dust even, fp 35 would make it a nice funfly delta, umm Outlaw also...

combatpigg

My Feedback: (3)

HI EE, If you were to set the .35 intake closing at 62 degrees ATDC, and go with an exhaust duration of 165 degrees, you should be able to turn an APC 8-6 about 19000. The exhaust port gets raised to get the duration. If you compliment these changes with a mousse can pipe, you might even get more, I haven't tried a MCP on this combo yet. It is pretty hard to streamline a MOUSSE CAN, so an extra 1000 rpm might not be worth it. It is hard to beat open exhaust for lightness and it's easy to streamline. I have done these mods to SUPER TIGERS and FOXES with great success. The best props for hot .35s' were the old TF 8.5-6.5 pylon series cut down to 7.8", but they are hard to find anymore. The other thing to do is put the carburetor away and go with the OS venturi, bored out to .250". A bladder is the best way to feed this set up. The .35 FP is a light engine, so you should be able to stick it in a 300 sq " model, make it come out to 2 pounds[ about .8 KG] and have a good time! The only bad part about this whole idea is if you are working with an old worn out FP. If this engine doesn't have much time on it, you can also shim the head away from the piston .005" more than stock and run 30-40% nitro, with 25% castor oil, and the rest methanol. Some guys like to run 50-50 synthetic and castor, I like pure castor in plain bearing engines.

Ian.W

alright, the motors crap for speed! but i want a smoothish thing to fly which will fly semi fast. even if i made 80mph id be happy. id have to re design it a bit. what do yuo all recomend for the wingspan and length, is my design too small

Cactus.

My Feedback: (1)

starjet, mini starjet....

combatpigg

My Feedback: (3)

The wing should be about 1 meter[1 yard or so] long. The airfoil should be semi symetric, or flat bottom with a fully rounded L.E. The airfoil should be about 7/8-1"[21-24mm] thick with a 8" chord, [counting ailerons]. If you prop it with a 8-7 or a 9-6 you should be happy with the speed. If you run it without the muffler, you might get it to 90 mph.or more, depending on how clean you make the model. If you are unhappy with the speed, take a couple of inches off each wing panel and see how you like it then.

MyWay

Combatpigg. The tt gp 42 is lighter than the os 35fp and can be modified to turn a apc 8/10 at 16000rpm on 15%. Give it a try you will be surprised.

combatpigg

My Feedback: (3)

WOW MY WAY! That's borderline awesome! Does it respond to the mods that I listed above? This would be one of those best kept secrets if what you are saying is true. I have a stock TT PRO 40 and it won't do anything close to that!

Ian.W

when you say running without a muffler you mean just nothing??? or some sot of pipe

MyWay

combatpigg. The tt gp 42 is the best kept secret out there. I haven't tried your mods as they are suited for high rpms with smaller props and a tuned pipe. Im sure it would work but not sure the engine would stay together at any thing over 18000 rpms. I set mine up to produce torque for high pitch 8/10 props and large diameter 11/4 or 11/5 props. I use just the tuned pipe header cut to the right length for max rpm on the test stand. I know a nelson or jett tuned muffler would bring more life into the engine but that would be defeating the purpose of using this motor to achive power while only weighing 11 oz. with minimal frontal area. The tt 42 from the factory is very conserative. Power is limited by low compression and a very small carb opening. Change just these two things and the motor will come alive. Oh, need to get rid of all the back pressure by removing the muffler. Also raise the exhaust .010''. Other work can be done internally but does not add but a few 100 rpm . This setup will spin a apc 11/4 at 15600 rpm. Not bad for 49$.

combatpigg

My Feedback: (3)

Thanks MYWAY, I'll bet a mousse can pipe on the TT 42 makes a great 3D set up with a 11-4. I like it when you can save money on the engine, and invest that money saved into something like beer!

EDIBLE, yep, no nothing, just an open exhaust port. The cheapest way I know of to get RPMs. You won't have much of a throttle, but if you are after speed, so what?

Ian.W

dont yo guys have sound restrictions???? weed getkilled for that, we got a 82db rule over here

MyWay

Some clubs do some don't depends on area. Working on something to quiet it down without loosing to many rpms. Maybe mousse can pipe like combatpigg mentioned. I would make one but I don't have a clue as to dimensions etc. Never seen one used around here.

RSands

Myway,

Would love to hear more about these mods! I have a 42 on a one off 3D design, and any other motor either doesn't have enough power, or weights too much, and the GP is marginal on power at best. I'm a newb to engine mods, but have messed with them a little, and can use a dremel and diamond bit. How would I fix the carb and compression problems? Really appreciate the help! Here's a link to building a mousse can http://webpages.charter.net/rcfu/ConstGuide/MCM.html

MyWay

RSands, Thanks for the info on building a mousse can. Im going to try it as soon as I can get the materials together. Hope it will work, however, if it does work im afraid I might have a time bomb on my hands. Thunder tiger engines are not designed for the power that can be achieved by modifying them for maximum power. I haven't blown one up yet but I feel im reaching the limit. You didn't say if you were using a mousse can. If you are, just opening the carb will help a lot. If you are not I will get into the other mods. Thanks again. MyWay.

RSands

Thanks, No, I'm not using a MCP. The design is extremely CG sensitive, so I'd rather not go that rough if possible. Appreciate your help!

MyWay

Try these simple mods first. These will get you about an extra 1000rpm. Remove the muffler and open up the stinger on the muffler as much as possible by grinding not drilling. Then try it with and without the baffle installed. Next open the carb to .240''. Any more and the motor wont shut down. The carb barrel is too small a diameter. You can however make the hole oval shaped ie .240''x.280''and it will work. I found that a diamond cutter works best as the barrel is very hard. When competed you should have a little bigger opening on the top of the carb than the bottom when looking at the carb with the barrel almost closed. This is important for a good idle on air bleed carbs. Just a little hand work on the body of the carb to match the oval hole and your done. Raising the combustion ratio requires a lathe. Try the simple mods first. Ill explain lowering the head .025 in detail later if you want even more power. PS . You didn't say what prop you were using. Ive tried them all and found that the apc 11/4 works the best on this motor in all applications except speed. Later . Myway.

combatpigg

My Feedback: (3)

Our club fields in this area have sound restrictions too, so I don't fly loud planes at club fields unless I've been invited. I can go for a short drive and find "out of the way"spots to fly the wild stuff. My experience with running sport engines at a higher rpm than what they were designed to do has been good ever since I started adding 8 ozs of caster oil to every gallon of hobby store fuel. Heavy plastic props are hard on connecting rods, but are a neccessary evil unless you want to go with wood. With the right prop, and the smallest , cleanest plane you can come up with, the 35FP should be able to be a lot of fun. If you copy the layout of one of the electric pylon planes, and bring it up to 300sq" or so, you'll have a neat little hot rod. It could easily be built at 32 ozs or less.

RSands

Thanks I'll give both a shot, and yep, using an 11 x 4 APC. Another 1K is gonna be night and day. Appreciate it.

acr007

These are my new flat sheet (reinforeced ) speed planes

Comments welcome, all will use a tuned pipe on a TT 42 or 46 Pro......

I am currently trying a few designs useing the KISS approach, keep it simple stupid.

I like the idea of the sheet balsa wings simple and esay to profile and thin, makes for a fast less drag wing and has great fligh manners, tested my hawk to stall and the nose drops getnly, loops well and turned on a dime/penny.

Windwalker

My Feedback: (2)

You designed the red jet?

Why not cut kits or frame-up some ARCS/ARFS for those of us across the pond?

You Brits shouldn't get to have ALL the fun!

WW

acr007

The red jet like the attached Tornado were existing plans which I altered from eletric to accept IC.

Easier tostart by adapting some one elses proven design and then learn the art before plunging in head first.

If I get my act together the latest jet below will be avaliable in a kit form from a UK web site wich I will publish in due course.

Plesae note the tuned pipe exits into the engine inlet, makes for a great effect at the field.....smoken babe......

Evil Homer

Would not mind the tornado, nice job, how does she fly?

acr007

Flew like on rails, pitty abount engine trouble. Will strip engine tonight and if terminal out goes the 42 and in goes a TT 46 Pro, should burn up the sky.