TOPIC: Profile F-15 Eagle for L-2

Looking good Roger. I can't wait for the wait for the flight testing stage.

My own building schedule has taken rather a 'hit' this week, so my F-15 is still in bits and I have little progress to report.

Fortunately Luke is rather more industrious than I am and has sent me these pictures:





Luke comments,
"To be honest, it's not my best work, I had some issues with dope glue and paint reacting, but it's passable for a prototype. I think the nose is a fraction too far back on the fuselage, not sure how I managed to do that, it looked okay before the glue set!

It has been a fun project thus far and as taught me a lot.

I found that the flat 1/16th fuselage sides tend to bow up, I have steamed them flat but wonder if they might need to be a thicker grade of balsa in a version 2? Not sure... I test glided it in the front room and it was clearly in need if a CG shift, so I added some weight to the nose by making a hole and inserting some lead into the balsa and then filling it.

Anyhow, it now ready to try out."


This is not a bad job at all, and it looks like it should fly ....

I noted the problem with the un-flat fuselage sides on my own model's parts. I hope to solve this with different dope to apply the tissue, but a better solution (for the mk 2) would be to change the direction of the grain so it's vertical rather than horizontal.

I hope to post some pictures of my 'take' on the F-15 quite soon. In the meantime, if anybody else would like to have a go (the template seems to be accurate enough to build from) just ask for copies.

Questions for Luke:

1. did you add any dihedral?

2. where is the CG? I want to know where to put the motor?

3. What does it weigh?

4. Where to put the downthrust tab ...

I've made a little progress today and will (hopefully) post tomorrow.

I have been working on the F-15 since Friday, but it's been slow going. I 'beefed up' the central section with cross grained 1/16" balsa sheet to ameliorate the warping Luke warned about, and added 1/32" cross grain balsa sheet to the sides to stop the same problem.

This the extra balsa did but, alas at the expense of added weight.

Wings and tailplane were covered before attaching to the central section with epoxy (for strength). The joints were cleaned up with 'Red Devil' light weight filler, and only then was the centre covered.(on both sides!).

The nose pod was shaped before covering and the 'canopy' painted light blue.
Detail was added to the metal effect jet-pipes and one of the rudders was hinged as a trimming aid.
I added metal protective foil to the underside and iinsides of the sides (!), as this is easier than adding it after assemlbley.

I tried, not too succesfully, to emulate the 'stealth paint' finish with a wash of acrylic grey.

IThe parts are now ready to stick together, starting with the motor mount:





I'm not sure Ithere is enough dihedral but it will have to do!

More later .....

Being somewhat dissapointed with the 'profile' F-15, I wondered if a built up model would not be more fulfilling. A quick Internet search came up with this:



This Guillows model is of course 'for display only' and non-flying, but could it be made, with a lot of modification and a bit of simplification, the basis for a flying model?

Quote from an old (2002) builders forum:

"These plane kits are not designed for flight, glide or power, so weight is not an issue. Several places in the destructions, reference is made to NOT covering the model a5t all for a "bones display model..." There's been some discussion around here as to what might be required to make these kits fly with power, Jetex, EDF, Rocket Engines, etc... It will require a completely different approach to the fuse construction, making it hollow, just to start with."

Hmm ....The kit comes with a nice canopy, anyhow!

Hi Roger,

Sorry didn't see these questions first time around.

CG is 3inches back from air intake.
Weighs 25g without motor
Dihedral 1cm on each tip

Luke

It's looking good Roger!

Certainly looks like an F15, look forward to seeing it in the sky

I have managed to glue all the various F-15 parts together. I was quite pleased with the air intakes. I was a bit concerned that the fins were rather vulnerable, so I put in some 22 SWG ali tubing to act as 'keys':



The fins were glued in place with epoxy. They seem quite 'firm' to me, but we will see what happens on the flying field!

I added 1mm of 'up' on each aileron to give some washout, smoothed off the surfaces with 1200 'wet or dry' and brushed on a coat of diluted Valejo satin varnish. Time for some photos:







My F-15 is a bit heavier than Luke's (a tad over 30g without motor) but there is plenty of wing area so I don't think it's a problem.
I'm sure I could make a lighter 'Mk 2', but we will see - we now have an F-35 to design and make! This will need a separate thread!

More later