Spitfire Hybrid

[Graham Davies 3]

Not sure if this is of interest, but I thought I'd share my latest project.

 

Following on from the short but bright life of my Cambrian Funfighter Spitfire. It's still alive, but has eaten props and ESCs at an unacceptable rate so is on the naughty step to think about what it's done. I felt that a similar model would better suit my needs. I loved the way the funfighter flew once it was up, but getting it there and then back down without something breaking was getting a bit tiresome.

 

I love what we used to call 25-size models. And now I have 3S 2200 packs doing nothing. So I have a design brief:

• Around 42" span and around 2- 2 1/2 lbs. That will mean decent performance on the 3536 1200kv motors I have, and 6 minutes of fun
• It needs to be a spitfire; that itch is not fully scratched yet
• I want retracts. I don't care if they are impractical. I may even still hand launch and belly land (fling and flop as we used to say), but they give me options for taking off, landing, and looking cool.

So, with huge thanks Peter Miller and Richard Wills (and in absence, Ian Peacock), a hybrid plan is hatched.

 

Peter has designed some beautiful models. Currently he is enjoying Destiny at our strip, and it is possibly the best looking sport model I have seen. In this series of models is Harmony. 42" Span and with a wing platform that is virtually identical to a Spitfire.

 

In my stash of plans, I have a plan by Ian peacock for a 42" Spitfire. There we have it; Harmony wing, Spitfire fuselage.

 

My adherence to Ian's design is very loose. I have been hugely impressed by Richard Wills' design strategy of using a 'crutch' and few formers. This ensures the fuselage stays straight. His use of foam decks makes life very easy, and I happen to have the 'scrap' pieces from inside my Yak decks, which looked a similar size. So I have used Richard's fuselage idea with Ian's dimensions. I chose to use a large battery hatch from spinner to behind the cockpit. This is to solve the terrible access to the motor the Cambrian kit has, and to allow me to access the radio gear. This is necessary becausue the model is one piece. Makes life a load easier and withstands belly landing in our tall crops that surround the strip.

 

The wing is close to Peter's design, but the section is thicker Peter kindly printed a set of rib patterns at 14%. I think the original is 12%. This gives me room for the retracts. I have moved the main spar back by 10mm to make room for 2.5" wheels, and used a slotted lightply main spar to save another few millimeters. Out of interest, I used foamboard for the outer ribs. A nice material to work with. The wing is fully sheeted becasue see-through spitfires are just not right! The sheeting is a little heavy due to the lockdown balsa shortages, but it's OK.

 

Here's a few pictures of the build so far.

 

She is A Harmony/ Spitfire hybrid. A Harmfire, if you will...

 

Graham

[john stones 1 - Moderator]

Nice. ?

[Peter Miller]

I am going to be most interested to see this on the field.

 

 

[eflightray]

The word 'hybrid' caught my eye, (Ok, so I drive  Hyundai Ioniq Hybrid).

If by model hybrid you mean balsa and foam ?, then I suppose my 72" Spitfire could be thought a hybrid also.

It is based on a free Tony Nijhuis Spitfire plan that was given away in a RCM&E mag 2012. The plan quoted around 15lbs with a 120 four-stroke - now that to an electickery junky was a red flag to a bull.

So my balsa and Depron foam version build came out at half that, actually 7lbs -2oz flying, includes 6s Lipo (1lb 9oz), retracts.

Ray. 

Apologies if this is a bit off-topic.

 

[Graham Davies 3]

Hi Ray,

 

My Hybrid is a mix of Peter Miller, Ian Peacock and Richard Wills designs, but it does also use balsa, foam and foamboard in the construction.

 

Your model looks great and is a fine example of how to save weight. How much does it follow the plan, or is the fuselage completely redesigned to use the alternative materials?

 

Graham

[Murat Kece 1]

15 hours ago, eflightray said:

The word 'hybrid' caught my eye, (Ok, so I drive  Hyundai Ioniq Hybrid).

If by model hybrid you mean balsa and foam ?, then I suppose my 72" Spitfire could be thought a hybrid also.

It is based on a free Tony Nijhuis Spitfire plan that was given away in a RCM&E mag 2012. The plan quoted around 15lbs with a 120 four-stroke - now that to an electickery junky was a red flag to a bull.

So my balsa and Depron foam version build came out at half that, actually 7lbs -2oz flying, includes 6s Lipo (1lb 9oz), retracts.

Ray. 

Apologies if this is a bit off-topic.

 

Hi

Could you share more on this. This is really good and the weight reduction is impressive.. Are the surfaces also covered with depron?

[eflightray]

Sorry Murat, but I rarely use the Model Flying forum for model builds, so no real detail available here, the build (2012), is on another model site but I'm not keen on posting links to other forum sites, seems unfair.

Could PM link you though, once I find how.

 

Ray.

 

[MattyB]

9 hours ago, Murat Kece 1 said:

Hi

Could you share more on this. This is really good and the weight reduction is impressive.. Are the surfaces also covered with depron?

 

A quick Google found it on RCGroups, it does look good and fly well…

 

 

Edited July 4, 2021 by MattyB

[john stones 1 - Moderator]

9 hours ago, eflightray said:

Sorry Murat, but I rarely use the Model Flying forum for model builds, so no real detail available here, the build (2012), is on another model site but I'm not keen on posting links to other forum sites, seems unfair.

Could PM link you though, once I find how.

 

Ray.

 

 

To P.M Ray, hover over members avatar, it'll show a message option.

[MattyB]

22 hours ago, Murat Kece 1 said:

Hi

Could you share more on this. This is really good and the weight reduction is impressive.. Are the surfaces also covered with depron?

 

There is also Electriflier's slightly bigger version to look at too - th build thread is on this very forum, and it is one of the most realistic Spits I think I've ever seen in flight due to the winglodaing...

 

 

 

[Graham Davies 3]

Morning all,

 

Quick update; the 'Harmfire' has now had around a dozen flights and is my new favourite model. It flies very well indeed. To quantify that, it solves the issues I had with the little Cambrian spitfire in that it is a lot lighter and so solo hand launching is easy. There is a reasonably significant torque roll to catch, but that's no issue. There is a huge power reserve on the current (sorry) set up of a 3536 1200kv motor spinning a 10x5 on 3S 2200 packs. 

 

The wing is 14% thickness and has 2 degrees of washout built in. The stall is pretty much a non-event and recovery is almost instant. The little model can be slowed down quite safely, but is still faster than is really needed. Certainly fun. However, for me the key point is it can be flown in a convincing way. The light weight and ample power means big loops are easy, and when my skills allow, slow, duxford type rolls are also possible. 

 

This is going to become first of a series; the pencils are sharpened and some obscure and lesser modelled 'birds are planned...

 

For now, here are a few flying shots Peter managed to grab through the gloom on Sunday. These shots are great considering how threatening the skies were. At several points, all I could see were the leading edge yellow bands!

 

Graham