HP115 repairs

Earlier this year I crashed my all Depron HP115 EDF lawn dart style so its repair is my next project.
The nose looked like this.

It now looks like this.

I think the reconstruction will have to be a bit unusual.
The front part of the fuselage was built as a half shell over the plan and when fully complete was added to the wing.
As the damage is much more severe on the RH side that half will be built over the plan and then added to the less damaged LH side.
This way there is plenty of scope for it all to go wrong or end up not quite 'true' but the saving grace is the nose plays little part in the plane's overall aerodynamics so it should still fly.
My aim is to get it complete for the Ashbourne Scale day on the 8th October.

Quite some work there Q, it would seem in this hobby, one has to not only be a good builder, but an equally as good repairer. Following your progress, boz.

The first few planks of the new RH fuselage nose half.

The keel planks are temporary and will be removed once the shell is lifted from the plan.
At the same time I will take the opportunity to revise the battery position and hatch as after it was painted (the great majority of the paint is behind the CofG) it tended to fly a touch tail heavy.
It was ok in super calm conditions but almost certainly contributed to its crash as the wind was the strongest I had ever flown it in!

The half fuselage planking complete or rather enough to allow it to be lifted from the plan.

Once the temporary keel strips have been removed it will be glued into the damaged nose where it will act as the support to rebuild the rest.

The LH nose section glued into position.

Still pretty flexible but it now gives something to work off to build up the RH half.

Still a long way to go of rather fiddly planking but with the basic structure in place it is now just a matter of getting on with it.

Not a great deal done what with painting the house and cutting the lawns but the RH side planking is slowly working its way round.

Once this area is complete the missing portion of the LH wing has to be made good.

Slowly the fuselage is made good with the planks joined to the undamaged areas of the skin.

Hopefully with a bit of filler and paint you won't even be able to see the join. .

Planking continues!
With the cockpit nearly complete 3 wing formers are added so the wing skin can be made good.

The next tricky bit will be creating the battery box.

With the cockpit canopy complete the RH wing skin is added.

That leaves just the battery compartment and nose cone to do but I fear quite a bit of filling and sanding will be required to achieve the original level of finish.

The fuselage is so deep (or maybe the battery so small!) that it can be mounted vertically.

The hatch will also lock it down.
This type is battery installation keeps it very secure with very little extra weight but it can be an issue if it swells!
All the skin is now complete.

The nose cone is made from of a stack of 8 laminate underlay 'rings'. It is similar to lightweight 'aero' Depron.

A bit of a faff to do but being so far in front of the CofG (36" or 90 mm) every extra gram has a big effect.

All put together and painted.

And it flies!
The only mistake was I made the battery box a snug fit for an 1800mAh 3s only to find the one I used has slightly different dimensions (by less than 1 mm!) to the other two I have. The others are such a tight fit I fear it might damage something trying to get them in.

I had forgotten about the size of the rebuild in 2017!
Although the latest crash looks relatively modest by comparison.

As is the way it tends to end up a more complex job.
Where the RH elevon was ripped away it crushed a portion of the wing tip which had to be significantly cut back so will need a part rebuilding.

A bit nearer the nose the wing leading edge was similarly crushed and will require the same sort of treatment.

The rest of the dings and dents (9 more!) should be simple(?) 'patch' repairs.

Thinking about the difficulty I had controlling the flight I noted that during the control checks the 'stab' function was working but it did not switch 'off' regardless of which switch was tried.
In hindsight I should have deduced something was wrong as on previous flights the 'stability' effect was dramatic when it was 'on'.

This does rather suggest that the crash was more the result of the stab not working properly than just the weather conditions but either way it is still down to "pilot error".

Structurally all back together.



And there are quite a few more small repairs not shown in these photos!
A bit of filling then some silver paint and finally try to find out what is amiss with the stab.