Essential P51 Retract Modification

Modifying the P51 Mustang's Retracts.  The plethoria of foamies on the market now out number the tradtional balsa ply and many come RTF (ready to fly) or ARF (almost ready to fly) Generally all the components are pre-fitted and all the user needs to supply are a receiver and battery power.

How do they sell them so cheap? By using cheap components, servos, ESC, etc, etc. Also depends on the importer requesting changes to the components, Century UK do.  I believe that these large EPO warbirds are made by Starmax and branded to the contract purchaser.

But can we improve them?  Of course, but may vary in expense to get the job done right.  . For the foamies with due respect, modern blow moulding methods mean models can be produced with excellent scale characteristics and in vast quantities.

The P51 Mustang Gunfighter or the Dago Red has great looks and one can see the appeal. However, you must bear in mind the shortcomings of this Mustang. And one of these shortcomings is the retracts. They are not really up to the job being plastic throughout, no steel pin pivot pin is the most obvious and which I found out on the first taxi in preparation for take off. In alighter small model they might just last a season with care but not in a big foamie, like the Mustang. This will be true for other warbirds in the large foamie class, ie; Corsair, Skyraider but to name a few.

To fit decent retracts will cost virtually 50% of the cost of the model in the first place which jacks up the outlay to get a decent flying model. But some of us will bite the bullet now we have been sucked in to buy the eyecatching Mustang. To put the retract issue right I am going to fit 25 - 46 Eflite retracts, priced at around £105 GBP in the UK. The next part of the story is the simplest modification with minimal time, an hour or so. There are a few other methods on other well known Forums but these involve a lot of cutting and making of ply beds for the retract to sit on.  Here I use the original fitments for simplicity.

You can see each stage in the photos as you read the article. Items required are: Eflite Retracts 25 – 46 size. Eight flat, wide washers with a 3mm hole.

Gallery

 

 

 

 

First job is to remove the original retracts by undoing the four screws in each wing. Carefully lift them out and lay them on the wing surface. Next using a thin blade or small flat bladed screwdriver lever the retract lead out of the slot in the wing. Take care not pull on the lead, just lift until the joiner is just proud of the wing surface. Unplug the retract lead making a note of which way up the signal line is, this ensures that you plug the new retract with polarity correct.

Slacken off the the two grub screws that secure the landing gear to the retract. Remove the leg assembly complete.

Remove the supplied legs from the Eflite retracts by slackening back the two grub screws and remove the leg gear. If you place the retract unit over the wing mounting area you will find that the spacing of two holes are the same as the original but two are slightly out of line. (no standardisation of mechanisms – shame)

Using a 5mm twist bit, drill out all the retract units mounting holes to 5mm. If you now place the unit back on to wing you will find that the original screw holes are now visible throught retract units bored out holes. Temporarily fit the unit and fix in place with the original screws. Don't tighten, just positioned. We are now determining how much foam we have to cut away to allow the retract to sit fully down. Mark the outline with a pencil. It should be just a little sliver from each side. Remove the retract and cut away the marked out foam.

Now you can refit the retract unit back into the recess, just lightly screw down and after plugging in the retracts lead into the wing extension lead push it back down into the slot in the wing.

Now you need to plug in the retracts into your receiver and power up the transmitter and receiver. I suggest you do each retract separately. Operate the retract switch. After two flicks of the gear switch the units will power up and move into “gear down” position. Now fit the original landing gear leg into the retract unit, ensuring the leg is fully pushed down. Using either of the two grub screws lightly nip the leg in the correct orientation. Now you need to watch the gear entering the wing recess. (I found in my case that the leg is too long now by 3mm and was the same in the other retract. I used a small angle grinder to lop off the 3mm)

You will be able to adjust slightly the retract's position at the securing screws later. However, if you legs are to long and the wheel catches the far side of the wing recess you will have to cut off a bit of the top leg.

Once you are happy that the wheels and landing gear open and close without binding you can now complete the modification.

Remove each unit's securing screws one at a time and put a flat washer under each head. I also used “star washers” for added security. These little washers have multiple sharp edges which bite into the metal. Plus we cannot tighten the screws really hard down without compressing the foam. Just nip them up firmly. That's it. Job done!

 

 

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