F15 parkjet ...

[solentlife]

First of all credit to Steve Shumate for an excellent plan ...

Having a few sheets of Depron at back on my room - I look at various plans to make anything from WW1 to todays fast jets in model form. I stumbled on Steve Shumate's plan for the F15 and it immedaitely struck me as the one to build. Profile is not really my cup of tea - but the F15 with it's squared style lends itself well to sheet construction.
Friend of mine years ago made one from the RCM&E magazine plan in 3/16th balsa .. 20 glow power - excellent and proved the sheet concept.

The overall sheme sheet attached .. (I hope Steve doesn't mind .. it is a free plan.. )

The plans are available to download and are at 75% and 120% ... I didn't realise the size of the 75% until starting to join the tiled sheets together .. but it's 20" span and fits my idea perfectly !

Unfortunately I got carried away with myself and started building before photo's !! Itchy fingers and all that.

As per my usual practice - I printed of the tiles, then with tape joined then together. Cut out out each part with a small border. Laid out on the 6mm Depron and with my trusty tapered reamer ... which has a very sharp point ... pricked through to the depron the outline of first pieces. I then cut these out .. position next prints .. prick and cut .. This way I can maximise the saving of Depron .. (all offcuts are bagged as well for repairs / small items later).

So here are the pieces (again I apologise for the part construction of fuselage and wing to strake) :



I do mark each piece as to ID .. so I can refer direct to plan easily .. with multiple pieces of item - I try to mark on inside where it won't show.

Wing and strake joined :



Stabilators and various small cap items :



other :



Fuselage front and rear married :





It will be noted that I have deviated from Steves excellent path .. in that the stabilator rod / holes etc. haven't been made .. this will be sorted before top deck applied.

Dry fit of major parts :







The design calls for a decent size motor and prop but that's on the full design size .. this is 75% and nice ... so I'm hoping that a medium set-up such as on the HK Parkjet will do ... a 1200 - 1800kv motor and a 6x4 .. 7x6 prop range ..

Nigel

[dahawk]

Nigel,

I don't think you can go wrong with anything Steve S has designed. Looks great !
He's an icon.

I built a little different version that had vectored rudder thrust. Could hand launch or r.o.g. from a grass field. Like all my other foamie profiles, I use a GH-V2 2212-06 yielding 24 oz of thrust at 19,000 RPM while drawing only 23 amps with a 6x4e MAS or APC

[solentlife]

My problem is the little bits like CF tubes etc. - VERY expensive over here ... so I may substitute with old antena tube for stabilators .. or fix front part and hinge rear.
My idea at moment is to use BBQ skewers right through fuselage and into fixed stab's ... 2 of them so they a) brace the structure, b) I don't have to cut / modify the fuselage / stabs too much. I can fit 2 small 4gr servos - giving me mixed surfaces ... ailerons with elevators for various as I find.

I used up a spare HK Parkjet CF mount that basically wasn't any use on a PKJ !! Meant modifying the foam .. but it fits nicely and I reckon with the lower power I'll put through this compared to the PKJ ... will be fine.



Nigel

[solentlife]

OK - decision made and elevators done (temp taped to stabs until I get mylar hinges in place)







Photos made with stabs under skewers for clarity .. final glueing will be with stabs on TOP of skewers with them embedded into slots ...

as here now with elevators taped in place ...





Unfortunately - just got my instructions for next assignment ..... so I'm travelling late tmrw or Monday and away for a while .... hope y'all can wait for finish of this little beauty !! I'll plug on as long as I can ...

Nigel

[earthsciteach]

I like that one! The profile planes don't appeal to me, either. Looks cool, Nigel! Would a 70 mm edf fit inside?

[solentlife]

Originally Posted by earthsciteach

I like that one! The profile planes don't appeal to me, either. Looks cool, Nigel! Would a 70 mm edf fit inside?

I'm considering building larger and fitting an EDF ... this size is not quite enough to get the 50mm in ... but maybe a bit of licence in deepening the fuselage ... and keep to the same size. There's only ~41mm depth inside the fuselage ...

But she is 'cute' ....

Nigel

[solentlife]

Radio installation ... thought some might like to see this .. I know I always like to see where people put their gear - helps me sort my model then.

Note that as I don't have a separate elevator servo sitting at the back - I will link ailerons and elevators on single servo each side ... I save tail weight.

Layout is :

Rx forward (FrSky 7ch)
Next bay back is LiPo, on this is a 3S 800 20C of 48grams
Then the ESC sits in the V of the fuselage sides inside the duct area.
The two servos are TG9e servos let into fuselage sides and then will have dual rods each to serve elevator and ailerons ...

The motor wires are extended with solid core copper wire ...







With this and final parts in place - she balances spot on ...

Nigel

[solentlife]

All in place ... canopy needs sanding ... edges rounded ... control rods to solder up and fit ...

She's ready for paint job ...













Balance as said is spot on and I reckon she'll do ok on a 800 3S ... I have other LiPo's if necessary !

Prop - initial ideas are 5x5 .. but suspect a 6x4 might be better ....... I also have 7x5 if necessary and the motor is capable of that size.

Nigel

[dahawk]

Nigel,

+1 on the dual purpose servo. I did it that way in my F4J Phantom and SU-27. On the F4J, the distance to the elevons was fairly long so I used Golden Rod. Worked great. Not sure what your AUW is but the only thing that would concern me is using the 800 3S. Seems like you might need more gooo ! Mine fly with nothing less than 1800 mah but most of the time 2200mah. Just MHO. Looking good !

[stuart]

very nice nigel!!

[solentlife]

Originally Posted by dahawk

Nigel,

+1 on the dual purpose servo. I did it that way in my F4J Phantom and SU-27. On the F4J, the distance to the elevons was fairly long so I used Golden Rod. Worked great. Not sure what your AUW is but the only thing that would concern me is using the 800 3S. Seems like you might need more gooo ! Mine fly with nothing less than 1800 mah but most of the time 2200mah. Just MHO. Looking good !

It's only 70% of Steves original design .. mine is 20" (500mm) wingspan. Smaller than the 50mm T45. So I think it will be OK ... I do have 1300 3S packs as well.
I may swap out the motor later to the 2800kv replacement motor that HK do for one of their powered gliders, but it will mean cutting into the model to sort the wiring.

I know I've made one mistake !! It was only after I glued on the wing and closed up I realised !! I put the ESC in a closed space ... no air flow. It should have gone into one of the ducts. I may use a long skewer to fashion a cooling slot into the frame via the inlets ..

While I'm away on this next trip - I leave house in 1 hr ... I'll have thoughts about colour scheme !

Nigel

[solentlife]

Solution !! Easy when you think about it ...

I cut two holes through fusealge sides behind the inlet fairing pieces that stand of from the fuselage ... so they are hidden but receive direct air. Then opened up the bulkhead to the ESC. The turtle deck now has a slot either side for air to exit that comes up through a slot in the wing from battery and ESC ...

So in fact now I cool both battery and ESC. The original design has no cooling of battery......

Happy now !!

Nigel

[solentlife]

Just tried a 1300 3S for balance ... luckily the battery position I chose is not too far ahead of CoG ... so it balances only 5 - 10mm in front of my calculated point. So it's still a good CoG ...
I have control rods to add + horns - so that will add a few grams to the rear ... help to balance out.

This little bird is one smart cutie ... can't wait to get back home and give her the sky !!

Request : Can people post up some interesting but simple colour schemes ? Not really fancying the standard USAF grey ...

Nigel

[dahawk]

How about a Red Arrows version? You know... F-15 on loan to RAF. At least you'll see it. I love my Red Arrows T-45 for that reasaon alone.

Have a safe trip !

-Hawk

[solentlife]

Originally Posted by dahawk

How about a Red Arrows version? You know... F-15 on loan to RAF. At least you'll see it. I love my Red Arrows T-45 for that reasaon alone.

Have a safe trip !

-Hawk

Some years ago when I lived in UK near Portsmouth naval area ... there was the annual Airshow at Lee on Solent ...
The USAF had 2 F15's come over specially modified to carry on one of the big US Aircraft. She was too big for enter to harbour and sat of in the Solent at anchor. The F15's took of and did display over the airbase ... passing right over low my apartment ... that was spectacular ... but the real show-stopper was when the RAF Tornado came in low ... under the F15, pulled up and looped round her ... I'd never seen that before and never seen again !

But the show had two displays that always make any Brit proud ... the Battle of Britain Flight (Lancaster + Spitfire and Hurricane escorts) ... seeing and hearing that Lancaster throttling to pull round ...

Then finale of course is the Red Arrows ..........


As to colour for the F15 model .... I need something visible, colourful but simple ... and I'd like to stay reasonably within actual schemes ...

Nigel

[dahawk]

Aw yes ! The kindness of the USAF pilots allowing a Tornado to make a nice display in front of the home town fans. I'm sure they didn't want to be rude. LOL

If it makes you feel better, I applied a British donut red white and blue dot stickers to my new Phase 3 F-16 versus the USAF decals. Pic later.


Have a good one !

-Hawk

[solentlife]

Originally Posted by dahawk

Aw yes ! The kindness of the USAF pilots allowing a Tornado to make a nice display in front of the home town fans. I'm sure they didn't want to be rude. LOL

If it makes you feel better, I applied a British donut red white and blue dot stickers to my new Phase 3 F-16 versus the USAF decals. Pic later.


Have a good one !

-Hawk

There's an old joke with RAF ... (my father who was RAF told me ...)

Under 500ft is RAF space .. under 50ft takes practice !

Go to youtube and see USAF and RAF prtacticing in the Welsh valleys low level stuff ...

http://www.youtube.com/watch?v=U_mUc...eature=related

http://www.youtube.com/watch?v=3-7zHlOi4T4

And having seen the RAF boys go out in Desert Storm ... the above is NOT low !!



Cheers
Nigel

[solentlife]

Question ............. the F15 at 500mm as I built .... what size EDF's would one work well with ? I'm wondering whether a couple of 35 or 40mm EDF's would do the job.
The fuselage has good construction to feed the air in ... leaving of the side pieces that reduce intakes would make them more than enough ... inside fuselage - it has a good tapered centre section allowing the ducts to feed nicely.

mmmmmmmmmmmmmm must look at this more closely !

Can't wait to get home ... get the pusher version painted up and in air.

Nigel

[solentlife]

Well here she is ready to have controls connected to surfaces .... (artistic liberty taken !! As far as I know - no F15 is in RAF service other than maybe evaluation guise .... so I took liberties with colours - using standard F15 grey with red / blue ... )









Sharpeyed amongst you will notice that exhaust pieces are not all fitted .... I decided to not bend in the sheets and fit the exhaust sides ... this is to maintain maximum air flow to the prop ... will see how she goes.

The motor is mounted a bit higher than the plan owing to using a spare Parkjet CF mount. This also raises the prop that little bit away from 'biting' launchers hand !!

The undersides are plain grey overalll to give a good contrast.

AUW with 1300mAh 3S 25C sits at 380grams .... the motor is 2200KV with 5x5 at present - but I reckon to stick a 6x4 on her ... just waiting Postman !

I have single 9gr servo each side to couple ailerons and elevators together ...
I have also described earlier my air-holes to cool the ESC better ...

I am really looking forward to this little gem's maiden. Once I get to know her character - I plan to build another with twin EDF's ... building at the smaller size - I thought would be too small ... but in fact it's ideal for small space flying - well I hope so !!

Nigel

[solentlife]

The motor when static tested failed to produce the required OOOOMPH !

So now have a 2627 3800kv motor fitted with a 4.9 x 5 prop ............ this now feels like she will have some get up and go !!

Nigel

[solentlife]

What an absolute beauty to fly ............
First launch - launcher stepped in front of me and I lost sight of her in those vital first seconds - but she climbed out a good-un.
2 minutes into flight - the motor cut ......... but she glided in well ...
Checking her later - found she had a poor connection ... sorted and she flew again
Videos are uploading to Youtube now ... of maiden and 2nd flight that day ... will link once loaded ..
Nigel

[solentlife]

Maiden flight Video :

http://www.youtube.com/watch?v=OG5hN7Ig7qM

then 2nd flight :

http://www.youtube.com/watch?v=PQkLu...1&feature=plcp

Now I've propped back to a 4.75 x 4.75 ..... sounds better .. but still not as high rpm as I expect from a 3800kv motor.

It's raining today - so not likely to trial her today ...

Nigel

[dahawk]

Looks and sounds great Nigel ! The only thing you need are some toothpicks for the antenna's that mount on the v-stabs. LOL You're again having way too much fun !

-Hawk

[solentlife]

Originally Posted by dahawk

Looks and sounds great Nigel ! The only thing you need are some toothpicks for the antenna's that mount on the v-stabs. LOL You're again having way too much fun !

-Hawk

As you notice - I have a laugh when out with the other guys ... too many people are so serious !!

But yes - I am having fun with this little gem ... she clocked 115kph - not fast - but being so small - it's enough !

Problem at moment is to sort her for the catapult .... the servo rods will fould the rails ........... but maybe once I get the prop / motor combo sorted - she'll be ok to solo launch. As you see in 2nd vid - she pulls away from launcher fine.

Nigel

[solentlife]

Well - of to Singapore saturday - so no more flying till I get back ...

Good luck guys -see you all later !

Nigel