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f-22 speed plane help wanted - my engine has arrived

Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

f-22 speed plane help wanted - my engine has arrived

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Old 02-13-2005, 12:48 AM
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Hotrodkid
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Default f-22 speed plane help wanted - my engine has arrived

due to some interest in my original thread about this plane, ive decided to go ahead w/ my dd-f-22 plan ...weird as it may be. teh engine & prop will be "tractor" style unless the proper sized prop can be found to make it a pusher formation

as seen below in my crude rendering, in going to mount the engine mid plane, and cut a opening in the top and bottom of the fuse for the prop to swing thru, the intakes next to the cockpit and the exhausts in back will be left open for air to draw thru, and ill do the math to make sure they will be equal in sixe so theres no real restriction, leaving me with a fuse that would have less drag then if i sealed them off

i need help picking engine, prop, airfoil shape and sizing the rear stabilizers. the below info is "to scale" , except that i stretched the wing root to bring the cg forward

wingspan ==== 34
overall length==45
wing root ==== 32
wing tip length =5.5
wing sq/in ====725
fuse width === 10.5
h-stab height == 7

cg is the purple line, estimated of course

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Old 02-14-2005, 02:35 PM
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Default RE: f-22 speed plane help wanted

Hmm... a mid engine. At least thats creative approach to CG issues. Should work ok.

Keep in mind the F-22 cross-section is pretty larger. The prop area displaced by the fuselage is fairly substantial.

(I was fortunate to have been part of the F-22 team during development. A few 'gliders' were built along the way for various reasons. The CG will be further forward than you think. The gliders balanced perfectly on the designed aircraft cg aft limit. The fuselage provides a large lift component).

You have a lot of wetted area, and a lot of wing area there. Its going to need a bit of power, and design it around an 11" dia prop. With the mid engine, anything from a "40" size to "60" size would be fair game.

Looks like a fun project. Keep us up to date.
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Old 02-15-2005, 03:01 AM
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Default RE: f-22 speed plane help wanted

i would like to stay on the high side of your engine reccomendation, as i was origaly thinking 60-70 range ... but since my thrusthp wont install (ms-dos errors for some reason) i cant play around w/ props to find what would , hypotheticly, be a good prop, any suggestions ?

this is one of the engines i was considering... as it has a rear exhaust, and the built in fuel pump would be a nice feature also : http://www.rcuniverse.com/market/item.cfm?itemId=76299

due to the need to have clearance around the prop for structural members, i was hoping that i could use a 3 blade prop instead of a 2 blade prop

it would seam that youd be able to use a smaller diameter prop if you used a 3 blader

yes no ?

i dont think the fuse will add much left either, for this model im just going to use straight sides and the bottom, and then the top will be one simple curve as seen below

(9 inch prop shown)
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Old 02-15-2005, 09:39 AM
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Default RE: f-22 speed plane help wanted

That YS 61 long stroke is a good engine. You would want a 12x12 prop on the front , and a full pipe out the back tuned to about 10K rpm. They were mighty good pattern engines.

Depending on your needs, the Jett FIRE 90L would provide some serious muscle. That is available with either a long pipe or the shorter tuned muffler. Higher rpm alternative.

For your initial development, you can probably use any decent 60-90 size engine. There are pleanty of Rossi 61 RE engines out there (still available new), MVVS, And some of the OS RE pattern .61 engines too.

You design lends itself nicely to favorable fuel tank placement. You can even use two tanks, one located on either side of the engine location. Keep the tanks close, even with the YS.

Design with at least a 10 inch, maybe 11 inch, and even up to 12 inch props if possible, and you will have a wide variety of options. For referency, the Jett 90 turns a 10x10 WAY up there, and does not mind. However, the are very few 9" props suitable for use on a modern 60-90 size engine.

In the end, you will have to match the plane/engine/prop as a unit for the best flight performance. There is simply no other way besides testing for this. The calculator will do you little good, other than as a reference. Build it...pick and engine and prop to start with..... fly it

Stay way from the 3-blade props for what you are doing here. Would be too much loss involved.
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Old 02-16-2005, 02:51 AM
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Default RE: f-22 speed plane help wanted

i think ill go w/ the ys .61 for now, and latter possibly upgrade to the Jett 90 if i can find one used,

as this is my first scratch built plane, there are plenty of unknows to me, it might not fly well at 130 mph or i personaly might not fly well at 130 for that matter , and id rather keep it more on the less expensive side

and while i realize that noone would be able to tell me exactly what prop would be "perfect", a recomendation for a "starting point" is always greatly helpful to us newbies

ive redesigned for a 12 inch prop, its tight , but it will most likely fit fine , but might have to clip the prop slightly to 11.5 if i cant keep tight build tolerances, and my vertical stab's will me plenty taller then the diagram below shows ( i forgot about them when starting the side view)

fuel tanks will be right where u said, and ill most likely use a heat gun to make the forward end more aerodynamic, or maybe dad can weld me up an aluminium or copper form fitting tank, but ill cross that bridge when i come to it

il probably move the engine forward some to get the proper balance depending on my final Rx / battery decision

MORE QUESTIONS:

1) whats the best control method to use ? control rods or pull/pull ?
2) what approx. sizes should i use for my control surfaces ?
3) what fuel ? ive got 15% for my spad, but i would assume speed planes use something hotter ...


thanks in advance guys !
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Old 02-16-2005, 02:56 AM
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Default RE: f-22 speed plane help wanted

and heres the rendering, green circle shows how im thinking of mounting the servo for the elevator, one on each side
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Old 02-16-2005, 03:13 AM
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Default RE: f-22 speed plane help wanted

For affordable speed, keep an eye on the swap-shop for a Rossi-60/61 FIRE, or for $100 bucks new a Tower-75 will turn an 11x8 VERY well for the $ (I ran a 10x10 on mine with good results-)

Fuel should be the least of your concerns, a Rossi or other European engine will run well on 0-5% whereas the TH-75 likes 15% at least---

Good luck and please keep us posted!
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Old 02-16-2005, 10:27 AM
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Default RE: f-22 speed plane help wanted

Agreed on the fuel....

Most of the speed ships you see discussed in here run on 15% or less. Typically, there is no need for more nitro. The European engines are designed for lower nitro.

That Tower 75 is a good engine. Unless you have your heart set on a RE for the prototype, you may want to consider that as a powerplant.

Rig conventional controls... pushrods. Use elevators and fixed stabs, rather than trying the flying stabs right off the bat (looks like that is what you are doing... you are on the right track). Once you have the basic aero and handling qualities stuff figured out, you can try to optimize things.
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Old 02-28-2005, 11:24 PM
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Default RE: f-22 speed plane help wanted

the ys 61-r showed up today, along with the tuned pipe, which is a whopping 25 inches long alone

i didnt take into account the length of the tuned pipe, didnt even ask when i bought the engine, so at the moment it hangs off the back quite far to get the balance correct

whipped up some new cad drawings to show engine placement

i also picked up my fiberglass materials from a buddy, and got an extra piece of mat from another friend, so theres very little i realy need, except an air tight final plan
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Old 03-01-2005, 04:50 AM
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Default RE: f-22 speed plane help wanted

hi, I was just wondering how do you start a mid mounted engine???
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Old 03-01-2005, 11:35 PM
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Default RE: f-22 speed plane help wanted - my engine has arrived

either a short section or string raped around the thrust washer (?) behind the prop, or if the tip of the nose cone sits below the top of the fus i can use a conventional tarter motor, i

ive usd the string idea before, just have to use a short piece, works slightly better then a chicken stick
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Old 05-02-2005, 05:48 AM
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Default RE: f-22 speed plane help wanted - my engine has arrived

slowly making progress, i got my wingcares a while ago and they have just been sitting here while i played around w/ ideas

i should have picked a larger size for my wings, what looked good on paper and made out of cardboard was obviously to small in real life, so i wound up making extensions to add some to the span, and might go one more "section" on each side

as combattpig said after he cut them for me (perfectly to my specs i might add) ... the original cores wouldnt be good for anything hevier then like 30oz .. my ys 61 alone is 16 oz w/o the pipe ....


seen below is the wings as they sit, simply taped together, and the center fuse section which is 4 pieces glued together ready for carving. the tuned pipe will be recessed into the bottom of the fuse and the engine will be fully cowled

im going to fiberglass the fuse seperate, cut the bottom open and carve the foam out , then combine the fuse to the wings with another coat of fiberglass cloth

ill be using 2 pices of dowel to hold the wings and fuse together for stiffness, and a hardwood engine mount on the insides of the fuse as engine mounts

tail boom section will be extended farther still, and will use f22 shaped H & V stabs

this whole project is taking way to long, mainly because i have noooo clue what im doing ..... the plane u see in the pics below just sits on the coffee table in the living room for me to stare at during the day for brainstorming

kinda ironic, i started this project wanting to build a speed plane that was unmistakable for an f22 ... but the farther into it i get the farther i get from my plan ... oh well

pic 1 shows the addition pices on the wing that i bandsawed from the extra foam combattpig used to pack my cores

2&3 are the overall progress so far

#4 shows the shape of the wind from the front
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Old 05-02-2005, 11:19 AM
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Default RE: f-22 speed plane help wanted - my engine has arrived

HRK, I still have the formica template hanging up on the wall. If you want more span, PM me and we can work out the details, Those other cores would be for a .15 to .32 sized project. Even though you will be flying on the fuselage too, a .60 is a big hunk of metal for those tiny wing panels. Why can't you down size your engine choice to a hot .32? That plane could be built real light, or it could very easily turn out like a brick, that seems to be the nature of unconventional designs. Every idea that is partially thought though will weigh more than those ideas that are completely worked out ahead of time. I like your general layout, but see no reason to install a 3 horse engine. I think an OS .32 or WEBRA .50 have great power to weight and great power to dollar. The THUNDER TIGER PRO .46 is another great $/power/engine, but a little bit heavy.
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Old 05-03-2005, 01:28 AM
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Default RE: f-22 speed plane help wanted - my engine has arrived

i think any way u cut it, due to this being the first scratch built im doing, weather its a hot .32 or this .61 ... ive got equal chance either way of it turning into a brick ... its the nauture of the learning curve just as much as its the nature of unconventional designs

on top of that, i dont currently have the leaway in my bank account right now to go out and buy a different engine

if i add one more core section to each wing, and the plane comes in below 4 pounds ... which it should since all the components come in at just under 2.5 pounds , then add the weight of foam, fiberglass and engine mount ... ill have a wing loading of 17 or less (assuming a 4lb finished weight that is)
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Old 05-07-2005, 05:22 AM
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Default RE: f-22 speed plane help wanted - my engine has arrived

gto a lil dusty the other day and started making the cowl for behind the engine, and later i will carve some thin pieces to box in the engine and continue forward to the spinner

ill probably bring the front section to a vertical point from the spinner to the top of the engine in an effort to streamline it as much as possible,

almost the entire top of the fuse will be one removable panel to access all the bits and pieces, after the top panel is carved ill fill it, make sure its perfectly shaped and wrap it in packaging tape to be able to make the top panel , then glass the entire plane w/ the engine cowl missing so the fuse up to the engine is airfoil shapped , then just notch it behind the engine for the header to drop thru

hopefully when its all done it will be strong enough to cartwheel on bad landings and not take much damage,

first picture of the cowling, from the rear
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Old 05-25-2005, 05:29 PM
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Default RE: f-22 speed plane help wanted - my engine has arrived

slowly making progress

fabbed an engine mount from hardwood, it will be bonded and screwed to the sides of the fiberglass fuselage

bonding area is 2 1/4" by 3/4"

considering the engine mounts to the mount w/ 2 screws an no epoxy, 8 screws AND epoxy should hold the mount to the fuse JUST FINE

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