ORIGINAL: wojtek
On the BVM web site, under the KingCat addendums, is outlined a problem with the booms delaminating and cracking, be it under flight ot landing stress/load, or during bumpy transport. My King Cat is nearing completion and I would like to reinforce this area prior to flight as a precaution, instead of waiting for the problem to develop to address it .. My question is, what can be done to reinforce the boom ? Some of the ribs and wood structure deep inside are balsa, some are plywood .. there is not mush access to get in and double up or reinforce any of the wood work, and i can not see how to get any rods or skin doublers in there either .. I have heard some people discuss possibly cutting the booms open to reinforce them, but I definitely do not want to go that far ... any suggestions ?? The only thought I had was to use low pressure polyurethane expansion foam, mixed with shreds of carbon fiber cloth ??? (would be very light and strong... (would run a tube through the boom for servo wires .. ) .
any and all ideas welcome !!!
Wojtek
Woj
The answer to your question in on BVM site that you referenced in your post.
See below for a copy:
There are at least 200 KingCats actively flying now and enduring the stresses of high speed flight, High-G maneuvering and less than perfect landings.
There have been problems recently with the booms on two aircraft. As explained in the previous A.D. (July '04), these semi-monocoque structures rely on the integrity of the glass/foam/glass laminate for strength. If the lamination is damaged, i.e. delaminated for any reason (even excessive squeezing during model assembly), there can be a soft spot in the boom structure.
This .020" carbon fiber boom reinforcement kit is offered to all KingCat customers at no charge for the parts and instructions. There will be no shipping charge for USA customers. Shipping outside the USA will be whatever is most economical.
If you have been flying your KingCat a lot and have confidence in the integrity of its boom structure, you may be satisfied with it the way it is.
If you have any concerns about them (booms), we highly recommend installing this reinforcement kit. It takes less than an hour and some SLO-ZAP to accomplish.
The thin machined reinforcement strips have a shiny carbon fiber weave surface similar to that used to decorate custom automotive interior panels. The aerodynamic shape of the side panels is also attractive and should not need any touch-up painting.
Boom reinforcement kits and very detailed installation instructions will become available to be shipped the week of September 20th, 2004.
Due to the numbers involved, it will take us about 4 weeks to supply all KingCat owners. New kits are being shipped with the reinforcement kit factory installed as of September 20, 2004.
Contact BVM at 407-327-6333 (tel) or 407-327-5020 (fax).